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December 26

Fog

What would happen if you boiled fog machine liquid? Would it make a load of fog? 82.44.55.25 (talk) 00:23, 26 December 2010 (UTC)

I know of two types of fog machines, one basically does boil water, so nothing would change. The other uses dry ice (frozen carbon dioxide), which goes directly from a solid to a gas, with no liquid in between (it sublimates). It's not possible to boil carbon dioxide at normal atmospheric pressure. If you pressurized it and heated it, you might get a liquid, and if you suddenly released the pressure, you might get a lot of "fog". StuRat (talk) 04:02, 26 December 2010 (UTC)

I am confused when you say "nothing would change". Do you mean nothing would change with the fog liquid if I boiled it and it would just sit there in the pot, or do you mean there's no difference between whatever a fog machine does to the liquid and just boiling it, so it would make fog? And I'm specificlly talking fog machine liquid, not dry ice. 82.44.55.25 (talk) 10:45, 26 December 2010 (UTC)

From fog machines Typically, fog is created by vapourizing proprietary water and glycol-based or glycerine-based fluids or through the atomization of mineral oil. I don't think boiling would vapourize it particularly effectively, I don't think you'd get a LOT of fog. Vespine (talk) 13:05, 26 December 2010 (UTC)

How about dropping dry ice into boiling water? ~AH1^(TCU) 17:43, 27 December 2010 (UTC)

What is the scientific term for levels of activity by time of day?

An organism is diurnal if it is active during the day, nocturnal if active during the night, etc, but what is the formal term for nocturnality and diurnality themselves? Is there a scientific word meaning "the level of activity of an organism by time of day" that includes diurnality, nocturnality, crepuscularity and all other variants on the concept? I've been wondering this for a long time but haven't been able to find this term despite a hard search. Circadian rhythm seems to be the most closely related concept that I've found, but it seems to be a bit broader than just activity levels. Abyssal (talk) 04:11, 26 December 2010 (UTC)

Chronotype? Clarityfiend (talk) 04:34, 26 December 2010 (UTC)

I don't think that's exactly what I'm looking for. That concept seems to be behavioral, like if a person (a diurnal animal) is a "night owl" (ie chooses to adopt different behavior). I'm more interested in activity levels innate to a species. Abyssal (talk) 07:24, 26 December 2010 (UTC)

Circadian? SpinningSpark 16:22, 26 December 2010 (UTC)

"The time during which an organism is normally active is referred to as the subjective day" - from Pace-Schott & Hobson (2002). NRN. 3, 591–605. Is this what you are referring to? --Mark PEA (talk) 21:39, 26 December 2010 (UTC)

Solar sails

Why aren't solar sails used to propel all spacecrafts? Since they don't require any energy other than to deploy and retract the sails, wouldn't they free up space that would've been used to carry fuel? --75.28.52.27 (talk) 20:31, 26 December 2010 (UTC)

They are difficult to make and deploy, take a long time to build up speed 82.44.55.25 (talk) 20:38, 26 December 2010 (UTC)

"Minimize total energy consumption" is only one objective during spacecraft engineering. While it is true that a solar sail will reduce the energy consumption, and consequently the mass of chemical propellant, a solar sail may incur other costs. Those costs compete against other design objectives - such as "minimize total flight-time"; "minimize flight-mass;" "minimize flight volume;" "minimize risk of failure;" "minimize monetary cost of spacecraft;" and "test specific scientific or engineering design." (With some imagination, you can expand that list ad nauseum). The point is, when you think of spacecraft design, you always have to keep yourself in the mindset of engineering tradeoffs and cost-benefit analysis. With present technology, even though solar sails might reduce the total mass of the propulsion system, they may significantly increase the flight-time - which is usually a tradeoff that the space-flight program cannot afford (because it affects the science objectives, the spacecraft design, and the dollar-budget). They may also introduce signficant risk - because they are both less-tested and less-controllable than a chemical rocket propulsion system. The chance that the propulsion system could underperform (or fail altogether) is altogether unacceptable, and generally outweighs any cost, mass, or other benefit that a solar-sail might provide. You might be interested in reading through the Lecture Notes for AA 222 - Multidisciplinary Design Optimization (a graduate course in spacecraft design from Stanford); you can learn how an aerospace engineer will formally specify the design requirements, evaluate various technologies, and plan the spacecraft. We also have the less-technical spacecraft design article, which mostly just links to articles about related subfields of engineering. Nimur (talk) 20:54, 26 December 2010 (UTC)

To date, Solar sails (skim the article, it's informative) are a basically untested technology. There has been a grand total of one spacecraft to successfully deploy a solar sail and use it for acceleration: IKAROS (Here's a news article about IKAROS, showing the sail). And it's only been up for about 6 months. If it successfully reaches Venus, and there are no major problems with the sail, other solar sail-equipped spacecraft may begin to appear; it's claimed in the IKAROS article that Jupiter is the planned next destination for a JAXA solar sail if this one works out. It's hard to find what exactly IKAROS is carrying (unfortunately, the IKAROS official website is woefully incomplete), but it appears that it's not accelerated solely by the sail: it also accelerates using an Ion thruster. I think it's safe to say that solar sails have a few years to go before becoming common on spacecraft.

It's interesting to note that ion thrusters, now pretty common on interplanetary spacecraft, were not really used in spacecraft propulsion until Deep Space 1, launched in 1998 (ignoring the SERT-1 probe, where one ion engine only ran half an hour, and the other one failed). If solar sails improve at a pace similar to ion thrusters, we may be seeing solar sails used fairly frequently in 20 years. Buddy431 (talk) 22:28, 26 December 2010 (UTC)

After the Japanese Spacecraft IKAROS the idea becomes more accepted. The Jupiter mission will be a lot of fun to see. The talks at COSPAR Bremen showed that JAXA has plans for the solar sail. By the way IKAROS do not use the sail to get faster they use it as a break! It is more efficient close to the sun and getting to venus or mercury are the best places to demonstrate the capabilities. The fact that IKAROS is going to Venus was not because of that, but simply it was the only mission which was launched at the right time with a piggyback capability.--Stone (talk) 22:49, 26 December 2010 (UTC)

Using the solar sale "as a brake" is essentially equivalent to using it to speed up; in space, it's the total acceleration (Delta-v) that's important, not which direction it's in. Buddy431 (talk) 23:14, 26 December 2010 (UTC)

Don't buy your solar sail on sale, or you may find it breaks when it brakes. StuRat (talk) 03:43, 27 December 2010 (UTC)

has any famous scientist ever expressed doubts about the moon landing authenticity?

bertrand russell, a very famous mathematician and philosopher, expressed doubts about the official jfk assassination story. did any famous scientists (like feynman, etc) ever express doubts about the authenticity of the moon landings? 87.91.6.33 (talk) 22:34, 26 December 2010 (UTC)

Why would they? It happened. The moon landings involved tens of thousands of people. Keeping that many people silent on a cover up for 40 years would be impossible. Wikileaks has shown us how keen some government employees are to tell the truth and release embarrassing information to the public. And I'm writing this as an Australian. The landings depended on people on around the world, including Australia, for communication. (Have you seen The Dish?) There would have been hundreds here involved. Nope. we wouldn't have kept America's secret, if there was one. HiLo48 (talk) 22:44, 26 December 2010 (UTC)

There are for sure some very old and very famous scientist expressing doubts about anything. The percentage of expressed stupid thoughts is not smaller because you are a scientist.--Stone (talk) 22:54, 26 December 2010 (UTC)

I would expect scientists to say stupid things less often than members of the general population. It's not never, but I would hope it's less frequent. Of course, they can do a lot more damage when they say stupid things because they have greater credibility (even if their area of expertise is completely unrelated to what they are talking about). --Tango (talk) 23:23, 26 December 2010 (UTC)

I didn't ask about old scientists but famous ones, like Feynman. So, did any famous scientist ever express doubts? 87.91.6.33 (talk) 23:49, 26 December 2010 (UTC)

Charles K. Johnson, president of the International Flat Earth Research Society declared that NASA faked the landings, which were staged by Hollywood with Walt Disney sponsorship and based on a script by Arthur C. Clarke and directed by Stanley Kubrick. The first link attests to Johnson being famous enough to be noted in Wikipedia and the second link is a report about Johnson in Science digest July 1980. Together these links establish Johnson as a Famous Scientist. Cuddlyable3 (talk) 23:52, 26 December 2010 (UTC)

I'm sorry, but calling Johnson a scientist on the basis of the fact that he was featured on a website called Science Digest (which isn't a scientific periodical at all) is utter, total, and unadulterated nonsense. --Mr.98 (talk) 01:37, 27 December 2010 (UTC)

Calling Charles Johnson a scientist can only be construed as a joke. His belief on flat Earth alone is enough to doubt about his mental health.Quest09 (talk) 12:19, 27 December 2010 (UTC)

I would hope so, but in my experience CL3 has had some difficult distinguishing nonsense from sense on the web before. I suspect that his or her above post was made in complete earnestness. I'd love to be wrong, though. --Mr.98 (talk) 19:51, 27 December 2010 (UTC)

Another issue is, what kind of scientist? Would the comments of a famous medical scientist mean anything on moon landings? Scientists are specialists. HiLo48 (talk) 23:54, 26 December 2010 (UTC)

WP:OR - The first time I ever met Doug Osheroff, he explained how after winning his Nobel prize for superfluid helium, all kinds of media and political people would call him up to ask his opinion about stem-cell research and space-shuttle disasters and junk. (Somehow even NASA thought he was "expert enough" about Space Shuttles)! But he was only really an expert on helium! He said, as a prestigious scientist, the public automatically trusted him to be an expert on everything scientific, all the time - which was really very silly, and demonstrated how little the public actually understood modern science. The second time I met Doug Osheroff, I didn't get to talk to him very much, but I did get to yell at him because he walked through our "DANGER DO NOT ENTER" barrier at the back parking lot behind the physics building, right into the path of our rocket pyro test (he was just trying to take a shortcut to his car, and delayed our entire procedure). He saw our sign and caution-tape, but he said he "didn't think it would be very dangerous." I guess my point is that even very smart and famous scientists can say stupid things; and you shouldn't always trust their judgement. Nimur (talk) 23:57, 26 December 2010 (UTC)

You just made a preemptive strike against something no one has shown. If you don't think it would be relevant for someone with a Nobel Prize in helium to express doubts about the space missions, you have that right. But me, I care a lot about whether in fact anybody like that did. Your response is like me asking "has any president been antisemitic?" and you saying: what if they were - that doesn't prove that Jews are bad! A president can be very wrong, why Nixon was a crook who would have gone to prison but for a presidential pardon from his successor!!! Why even ask that question??? head asplode. 87.91.6.33 (talk) 00:27, 27 December 2010 (UTC)

I'm sorry. Allow me to clarify. Out of all the famous scientists that I know, none has ever expressed doubt to me about the veracity of the manned moon landings. Nimur (talk) 00:43, 27 December 2010 (UTC)

There's a list of people at Moon_landing_conspiracy_theories#Hoax_proponents_and_their_proposals, some of who are scientists. 82.44.55.25 (talk) 00:52, 27 December 2010 (UTC)

Yes, there's a list of people, but only one of them appears to qualify as being a scientist - Alexander Popov - described as a Soviet physicist and inventor with the degree of Doctor of Physical-Mathematical Sciences. Dolphin (t) 01:16, 27 December 2010 (UTC)

And his area of specialisation appears to be around light - lasers, spectroscopy, etc, so hardly an expert on flying people to the moon. HiLo48 (talk) 02:15, 27 December 2010 (UTC)

Are there any scientists whos field of expertise is "flying people to the moon"? I always assumed the teams of scientists who do these kinds of things have a vast array of different areas of expertise which they apply to the task at hand... 82.44.55.25 (talk) 11:04, 27 December 2010 (UTC)

The evidence available on Wikipedia is very comprehensive regarding high-profile people known to believe the manned moon landings didn't occur. That evidence indicates that no scientist whose field of expertise is directly relevant to manned moon landing believes NASA's manned moon landings were hoaxes expresses doubt about the authenticity of these landings. Dolphin (t) 12:27, 27 December 2010 (UTC)

Thank you, although you switcheroo "none of them express doubt" into "none of them believe it is a hoax". I will accept your answer as really reading as the former. (Since there are, in fact, many reasons one could doubt something without expressing it publicly). Thank you. 87.91.6.33 (talk) 15:19, 27 December 2010 (UTC)

There was nothing significant in my choice of words. I have struck the original words and replaced with words closer to the original question. Dolphin (t) 07:15, 28 December 2010 (UTC)

You're right, of course. In fact the Apollo program was used a great example of excellent project management for the way it brought together the diverse resources it required. The points made above about specialisations among scientists were simplifications, but still relevant. HiLo48 (talk) 11:22, 27 December 2010 (UTC)

In the case of Popov, he would be an expert for the purposes of evaluating moon landing hoax claims if those claims were based on evidence generated through laser spectroscopy. His pet conspiracy preference, however, revolves around the notion that the launches were faked using Saturn 1B rockets disguised as the (much larger and putatively non-existent) Saturn V. Leaving aside the political propaganda angle (Soviet scientist denies American accomplishment during Cold War, film at eleven), he might be a credible source on this question if he had a background in military reconnaissance, remote imaging, and aerospace engineering. Because his conclusions are based on matters far outside his own specialty, he should be taken as no more credible than any other randomly-picked clever-but-gullible individual. The fact that his day job is as a 'scientist' isn't helpful here, any more than being a 'doctor' is sufficient if a dermatologist were to tell you that you needed heart surgery. TenOfAllTrades(talk) 15:06, 27 December 2010 (UTC)

If my dermatologist were to tell me he strongly suspects I have a heart problem, I would take it seriously! A lot more seriously than if Aunt Em did. 87.91.6.33 (talk) 15:24, 27 December 2010 (UTC)

Speaking of switcheroos, I see what you did with my words there, and it was rather sketchy. I said "heart surgery" not some generic "heart problem". In most places, a dermatologist is a full medical doctor, but one who has additional specialist training. (The same is true of cardiologists and cardiac or cardiothoracic surgeons, albeit with a very different sort of specialization.) I would expect a dermatologist to capable of detecting certain overt types of heart conditions (and indeed, some conditions are associated with specific dermatologic markers) — but it wouldn't be appropriate or expected or credible for a dermatologist to authoritatively prescribe cardiac surgery. TenOfAllTrades(talk) 17:47, 27 December 2010 (UTC)

December 27

Crocodile Dundee II

I know it's "just a movie", but I'm still curious: in "Crocodile" Dundee II, Dundee jumps off a building, holding a rope, and about five or six stories down, the rope snaps taught, and he swings right through a window. Assuming the rope could never break, would this stunt even be remotely possible, without ripping skin off one's hand, etc.? – Kerαunoςcopia^◁_galaxies 08:32, 27 December 2010 (UTC)

It presents a number of genuine difficulties so it would be reasonable to assume this stunt could not be achieved in real life, only in the composite world that can be achieved in film - shoot a number of different sequences, each one entirely ordinary, and then splice them together to give the audience the overwhelming impression that this extraordinary action is not only possible, but that it actually happened. Dolphin (t) 12:04, 27 December 2010 (UTC)

What is interesting is how close one could come, with a sufficiently stretchy rope, careful measuring, and careful training. But if you fall 5 stories down, and the rope "snaps" taught" , there are several g of acceleration involved, and you probably rip of some body parts. --Stephan Schulz (talk) 13:16, 27 December 2010 (UTC)

While we're being technical and nitpicky, "snapping taut" is a very hand-wavey description of what's actually happening. The rope is simultaneously undergoing several processes. First, it is undergoing a long-duration inelastic collision with the person (who is otherwise in freefall) and with itself (because, as we model it with continuum mechanics, a continuous distribution of infinitesimal connected rope pieces, each with their own infinitesimal mass, momentum, position, and so on). The duration of that collision is non-zero and in fact begins at the instant the jump begins. The rope is also compliant to some extent - even a very tough rope has some elasticity - so there is an elastic deformation (stretching) of the rope that also absorbs some of the energy of the fall. The best way to estimate the feasibility would be to consider the energy per unit time that the hands must absorb in order to remain attached to the rope. This is easy - consider the trajectory of the fall; model or measure the instantaneous velocity and position, and construct a power dissipation graph vs. time. If at any time during the fall, the hand must absorb more power than the material (skin) is able to withstand; or if its contact force is greater than the hand can sustain (this is a bit gross, but a human hand has a threshold before it starts to break or tear skin). If we allow the hand to slide (so that the man actually slips down the rope as he falls, in addition to swinging), we have more parameters to estimate - the contact force between hand and rope; the coefficient of friction; and the dissipated energy there. The point is, we could accurately model all of this, and come up with some realistic bounds for jump length, rope flexibility, hand strength, and so on; given these parameters, we could estimate a maximum amount of swing before the action movie scene goes from "dangerous / implausible" into the realm of "physically impossible." Nimur (talk) 16:41, 27 December 2010 (UTC)

It's really not all that difficult, if you have the rudiments of Rappelling down. Here is a short humorous video clip of a firefighter attempting to make a two-story controlled rappel-drop into a window. WikiDao ☯ (talk) 17:02, 27 December 2010 (UTC)

On the other hand, yes: it was just a movie, the main character of which is supposed to be capable of awe-inspiring feats like that as far as I know, I haven't actually seen it so I really shouldn't say. WikiDao ☯ (talk) 20:27, 27 December 2010 (UTC)

Problem 1: G forces. Solution: An elastic "rope". Also, don't hold onto rope directly, but use a harness that distributes forces over more than just your hands.

Problem 2: Too much downward force and upward rebound, and too little lateral force toward window. Solution: Don't jump straight down, but rather follow something closer to a circular arc, by running off the roof.

Problem 3: Hitting the window, not the wall. Solution: Careful planning, taking into account the elasticity and length of the "rope", and the exact location, speed, and direction on which one leaves the roof.

Problem 4: Getting sliced up by window. Solution: Special "stunt glass" designed to break easily and safely.

Problem 5: Keeping from being dazed and useless after going through the window. Solution: Practice. StuRat (talk) 18:26, 27 December 2010 (UTC)

Perhaps it could be done with a bungee jump rope. 92.29.122.99 (talk) 19:42, 27 December 2010 (UTC)

• This sounds like the perfect thing to suggest to the Mythbusters. — The Hand That Feeds You:^Bite 22:29, 27 December 2010 (UTC)

Great answers, thank you everyone! I'm not sure how to suggest anything to Mythbusters, but it could make a neat segment. – Kerαunoςcopia^◁_galaxies 02:31, 29 December 2010 (UTC)

Is the earth gaining weight?

I couldn't find an answer in the archives. But with my limited knowledge of science, with all the people being born and gaining mass throughout the centuries, shouldn't the earth be gaining mass? Or is the earth losing energy to each living person? I ask, because in the movie Houseboat, Cary Grant explains death to his son in terms of a pitcher of water that is poured back into the earth. I understood where the death of a person becomes the earth, but I don't understand where the mass of a born person comes from. – Kerαunoςcopia^◁_galaxies 08:42, 27 December 2010 (UTC)

Try to reproduce without ever eating, and then ask again. Feezo (Talk) 09:02, 27 December 2010 (UTC)

Yes. We eat plants, or eat animals that have eaten plants. The plants appear to grow from nothing (apart from a seed), but in fact they are grabbing carbon and oxygen from the air, where we don't really notice its weight or size. I always thought this was one of the more amazing things about plants when I first learnt about it. All that bulk in giant trees was once just air. HiLo48 (talk) 11:06, 27 December 2010 (UTC)

Energy that comes from the sun could be converted into mass. Then again, the same energy could be converting the Earth's mass into energy. An interesting idea. If we could calculate the amount of sunlight absorbed by Earth, then we could calculate an upper limit on mass gained. I think my mathematical modeling class would have handled this. ;) Magog the Ogre (talk) 11:28, 27 December 2010 (UTC)

It's a fairly easy calculation. The average insolation at the top of the Earth's atmosphere is 1366 watts per square metre. The Earth's radius is 6371km and its albedo is 0.367. The energy gained in a second is insolation*cross-sectional surface area*(1-albedo). In this case, we get 1.1*10¹⁷W. Divide that by the speed of light squared and we get about 3kg per second. --Tango (talk) 11:54, 27 December 2010 (UTC)

The Earth is also gaining weight through meteorites that are trapped by her.Quest09 (talk) 11:56, 27 December 2010 (UTC)

Magog and Tango's answers are ridiculous, Magog has turned E = mc² on its head and using it in the wrong way, and Tango is encouraging him. Energy radiating from the sun, does not turn into mass on Earth. That equation has to do with nuclear physics, far removed from the concept you're talking about. The Earth loses mass in the form of the lighter gasses in the atmosphere escaping the Earth's gravitational attraction, gasses like helium and hydrogen. On the other hand, the sun is adding the same gasses back by radiating the Earth with solar wind however, I don't know the net gain or loss of these gasses relative to the Earth. In addition to these, as Quest09 has said, space debris, like meteorites, continuously rain down on Earth. Material that makes up the biosphere is continuously being recycled. That, is live does, life takes a chaotic mess of matter, and with the use of energy from the environment, shapes it into something with complexity and order. Death releases the energy back into the environment, letting the order and complexity decay back into a natural tendency of chaos. A simple example of thermodynamic law of entropy. You ask where the mass of a born person comes from? Think of a brick wall, a brick wall does not grow wider by stretching the bricks, instead new bricks, made from fresh clay must be added to the wall. Similiarly, a person does not grow by stretching, new cells must by made by their body. These cells do not appear out of nothing, they are made from what the body can extract from the very food we eat. This applies to whether a person has been born or not. In simple terms, we are build from what we eat, don't take this literally, this is an oversimplification. For the unborn, who not yet eating for themselves, has their mother to eat for them, since they share a body for the time being. I hope this answers your question. --Plasmic Physics (talk) 12:42, 27 December 2010 (UTC)

Nope, Magog and Tango's answers are completely correct. Energy radiating from the sun most definitely does turn into mass. However the earth also radiates into space, and looses mass that way, and the two are in balance. The earth also gains mass from interplanetary dust, and meteors. Also from solar wind. It looses mass from gases escaping, and technically from radioactive decay in the core (as stuff decays it gets lighter, and the mass is radiated into space as heat). Overall I believe it's gaining mass. Plasmic Physics: e=mc2 works both ways. A stretched rubber band actually weighs more than a relaxed one, and I don't mean in some nuclear way - I mean if you had a scale to weigh it on, it would actually weigh more. Same for chemical reactions, and everything else. Ariel. (talk) 20:09, 27 December 2010 (UTC)

You probably mean that it loses mass. Even though, in this case, it's also true that it looses it unto the deep.... --Trovatore (talk) 22:35, 27 December 2010 (UTC)

I agree that there are all kinds of other factors that result in the gain and loss of mass, but sunlight being absorbed does add mass at approximately the rate I said (I think I miscalculated and it's actually more like 1kg per second, but that isn't important). If E=mc² then m=E/c², there is nothing wrong about that. The extra mass is because the total mass of a glucose molecule and oxygen molecule is greater than the total mass of the water and carbon dioxide that they were made from (see bond energy). The other factors may be significantly greater in magnitude, but that doesn't mean that what Magog and I have said is wrong. --Tango (talk) 13:24, 27 December 2010 (UTC)

Actually Tango's logic is exactly correct - but there is a fatal flaw in his arrangement. He only calculated incident radiation - and completely forgot to compute the net radiation - which is (roughly) "amount of input energy from Sun" - "amount of thermal energy radiated by Earth." This amount, called the net energy flux of Earth (or "Earth's energy budget"), is incredibly important as a parameter of planetary and climate science. In fact, when climatologists and planetary scientists discuss "global warming," they are trying to compute an exact value for the net energy flux - i.e., is more energy coming in than going out? (If so, the planet is warming). Most estimates of net energy balance place it around 1 to 3 watts per square meter; though there are huge debates about this. Some scientists even believe the net flux is slightly negative (and that Earth is actually cooling). Many scientists believe that human-created pollution can change the energy flux - mostly by affecting the chemical balance of the Earth's stratosphere (adding Carbon Dioxide, for example, and changing the incoming and outgoing radiation rates). In truth, the exact amount of net energy is hard to determine, and there are a lot of "fudge" factors; and defining the "edge" of the Earth is very hard (i.e., if the magnetosphere experiences a net warming but the rest of the atmosphere experiences a net cooling... has the planet warmed or cooled?) In any case, Tango's approach is valid - if there is a net change in the thermal energy, this will exactly follow the conventional relativistic equivalence between energy and mass - and does affect the gravitational mass of the Earth. But, because of the disparity between incident and net energy flux, Tango's 3 kg/second is off by approximately 3 orders of magnitude. As such, Earth gains far less mass from solar radiation of energy than it does by gravitational capture of micrometeorites. (That is a very real and measuarable effect that you can read about here: The micrometeoroid mass flux into the upper atmosphere... (GRL 2001), describing quantitative RADAR measurements (from Arecibo Observatory) of meteorite rate. Nimur (talk) 13:44, 27 December 2010 (UTC)

The mass of the Earth generally does not change on short timescales because the mass that any organism gains is aquired from other organisms or compounds within the Earth's biosphere. Since we don't purposefully eat micrometeoroids, our mass gained comes entirely from the Earth, and returns to the Earth when we decay. The extra mass gained from meteoroids and meteorites is small but accumulates over time, though this too is likely balanced out by the ejecta that leaves the Earth's gravitational pull during periodically much larger collisions. ~AH1^(TCU) 17:37, 27 December 2010 (UTC)

I don't know about ejecta leaving Earth. Wouldn't any meteor large enough to do that also rupture the Earth's crust and destroy all life on Earth ? There is a theory that the Moon was formed that way, in the early days of the solar system, but nothing since then, I believe. StuRat (talk) 18:16, 27 December 2010 (UTC)

The flux of micrometeorites and interplanetary dust is about 2.5 ×10⁶ kg/year [1]. If it were a single rock, that would correspond to about a 10 m cube / year. I don't think the rate of ejecta is anywhere near that large. Dragons flight (talk) 19:21, 27 December 2010 (UTC)

My point was entirely that all food that gives mass to life on Earth comes from the sun; thus I was using the e=mc2 function. Obviously, the function will heavily overestimate, especially in view of the fact that much of the energy from the sun is defracted back into space (most, I believe; there just aren't enough greenhouse gases here). And, like AstroHurricane has pointed out, we don't actually eat astroids, so it seemed tangential to the OP's question. Magog the Ogre (talk) 21:19, 27 December 2010 (UTC)

Sure we eat asteroids, after they fall to Earth and mix with the other soil, which is absorbed by plant roots, eaten by animals, and finally us. And "...all food that gives mass to life on Earth comes from the Sun" is just wrong. Pretty much only hydrogen and helium come from the Sun, while most of our bodies are made from heavier elements from supernovas which happened billions of years ago, before the formation of the solar system and Earth. StuRat (talk) 22:04, 27 December 2010 (UTC)

The energy comes from the sun, I meant. Magog the Ogre (talk) 22:32, 27 December 2010 (UTC)

Yes, most of the energy comes from the Sun, but there are some organisms that get their energy from volcanic vents on the ocean floor and geysers, etc. StuRat (talk) 23:30, 27 December 2010 (UTC)

A point I find fascinating is regarding how trees and plants grow mostly out of "thin air". Because of conservation of mass, when you burn a tree you are left with ashes which are pretty light, but if added the mass of ALL the gasses that escaped while you were burning the tree, you would end up with the same mass as the tree you started with! I still think that's pretty incredible. Vespine (talk) 23:20, 28 December 2010 (UTC)

I think most of the mass of plants comes from the ground, in the form of water (and a few minerals) absorbed through the roots. StuRat (talk) 00:52, 29 December 2010 (UTC)

There's a lot of discussions about this on the internet, (search "where does the mass of a tree come from"). My impression of it is that most come to the conclusion that "the ground" is not correct and that most of the mass is from the carbon extracted from the air. Vespine (talk) 01:17, 29 December 2010 (UTC)

But most plants are around 80-90% water, which contains no carbon. StuRat (talk) 07:01, 29 December 2010 (UTC)

Yes, I suppose it is, if you look at it that way. However, I don't think it is unreasonable to argue that the water is "drawn up" into the tree, not that the tree is actually made out of water. The tree is made out of wood which is cellulose, lignin and other organic carbon containing molecules. Vespine (talk) 21:38, 30 December 2010 (UTC)

The water is both within and between the cells of a plant, so I certainly consider it to be part of the plant, just like I consider the water in my body to be part of it. But, then again, your definition allows me to claim I weigh under 100 pounds, so I'll tell everyone I just lost a lot of weight. :-) StuRat (talk) 01:26, 31 December 2010 (UTC)

Thanks everyone for your responses, this is exactly what I was looking for. I didn't realize I was essentially asking "Where does the mass of a tree come from?" but I sort of had to wonder about the ethereal part of the human soul, but no one mentioned it (or if billions of souls would even register against billions of human bodies). Still, I think this is all fascinating, thank you! - Kerαunoςcopia^◁_galaxies 02:30, 29 December 2010 (UTC)

Yowzer! Since science has absolutely no evidence of "souls", even with our most accurate instruments, I'd say we can confidently say that even if there is such a thing as a soul, they do not add to the "mass" of the earth. Vespine (talk) 03:39, 29 December 2010 (UTC)

It was just a mere curiosity : ) – Kerαunoςcopia^◁_galaxies 06:26, 29 December 2010 (UTC)

voilation of parity in beta decay

question:how parity is voilated in beta decay? — Preceding unsigned comment added by Awanishkt (talk • contribs) 11:13, 27 December 2010 (UTC)

Is that a homework question? If not, can you elaborate a bit for our edification? Magog the Ogre (talk) 11:29, 27 December 2010 (UTC)

I guess voilation is a misspelling of violation. I don't know the subject but the Google search violation parity "beta decay" gives hits, for example Parity (physics). PrimeHunter (talk) 14:33, 27 December 2010 (UTC)

I kind of like the root word "voilà", meaning "...to suggest an appearance, as if by magic": [2]. StuRat (talk) 18:06, 27 December 2010 (UTC)

People getting fat

So now it turns out both the British [3] and Australians are getting fat too. It has by no means been limited to the US, premature reports aside. In the US, it's fashionable to blame it on high fructose corn syrup, but I haven't a clue if that (uneconomical but for poor legislation) concoction is even available in Britain or Australia. It's clearly something to do with lifestyle or wealth. What in the world could be the cause of all this? Magog the Ogre (talk) 11:25, 27 December 2010 (UTC)

McDonald's, Subway, Aldi, Burger King, Monosodium glutamate... Always read the criticisms sections. It is ddefinately not only high fructose corn syrup (although I haven't read the article) — Preceding unsigned comment added by Eu-151 (talk • contribs) 11:51, 27 December 2010 (UTC) --Eu-151 (talk) 11:52, 27 December 2010 (UTC)

Why would monosodium glutamate make you fat? Some people claim that it is unhealthy, but it is only a salt, and I suppose with little content of calories. Quest09 (talk) 13:25, 27 December 2010 (UTC)

I agree. MSG may have health implications (I haven't looked into it), but it doesn't make you fat. --Tango (talk) 13:27, 27 December 2010 (UTC)

MSG tends to be in foods that do make you fat, and makes them more appealing. That's the theory, anyway. - Jarry1250 ^{[Who? Discuss.]} 13:51, 27 December 2010 (UTC)

And also it's supposed to be an appetite stimulant. That is, even if you got it in an IV drip, it would still make you hungrier. (I make no claims that this is true, only that it is one theory.) StuRat (talk) 17:52, 27 December 2010 (UTC)

I don't think we use HFCS much here in the UK. It doesn't matter what the source of the calories is. If you consume more calories than you use, you will get fat. It is that simple. People are getting fat because they are eating too much and exercising too little. There is nothing more to it (you can try and explain why those things are happening, of course, but blaming it on particular types of food isn't going to help). --Tango (talk) 13:27, 27 December 2010 (UTC)

Specific kinds of food could be an issue here. If something is a calorie bomb, you can ingest lots of calories with just drinking or eating a little of it. Quest09 (talk) 13:37, 27 December 2010 (UTC)

This article lists some research into it and provides some explination:Division of Nutrition and Physical Activity. Research to Practice Series No. 2: Portion Size. Atlanta: Centers for Disease Control and Prevention, 2006. The UK and Down-under are copying the American food industry -so the problem spreads.--Aspro (talk) 15:04, 27 December 2010 (UTC)

The lack of exercise in modern society, and the lack of a standard physical education system (!) in 49 American states must play a role as well. ~AH1^(TCU) 17:33, 27 December 2010 (UTC)

I agree that consuming too many calories and burning too few is the problem. Consuming too many is a result of large amounts of unhealthy food being provided cheaply and conveniently, as by fast food restaurants, vending machines, and pre-packaged processed junk food, like chips/crisps. If you had to pay a lot for potatoes, then had to make the fries/chips/crisps yourself, then clean the pots, pans, and dishes, you would tend to eat a lot fewer.

The Internet seems to be a big factor in reducing exercise, but perhaps there's some hope in Wii-type games, which require participants to exercise in order to win. Perhaps one day we will be running marathons on tread-mills surrounded by wide-screen TVs, with our friends on the screen beside us. Rising gasoline/petrol prices may also encourage us to walk or bicycle more. StuRat (talk) 18:01, 27 December 2010 (UTC)

People eat more and more food that is high in fat (main culprit), and also sugar. It has high calories but little bulk or fibre, so even when you've eaten too many calories you still do not feel full or satisfied. People do not eat enough fruit'n'veg which does fill you up with few calories. Modern food has become too readily available, too cheap, and over the years the food retailers sell has evolved to become more and more delicious. I remember when I was a child rather long ago, there wasnt any convenience or junk food apart from fish and chips, and I was slim. A practical means of losing weight may be to eat as much fresh fruit'n'veg as you can, as then you won't have any room left over for junk food - at least that's what I've found. 92.29.122.99 (talk) 19:32, 27 December 2010 (UTC)

I think people are getting fat because they are not eating enough fat. People are eating carbohydrates instead, but you need more of them to give a full feeling, so people eat too much. If they added some fat to the meal they would feel full earlier and eat less. And especially if they chose fats with good components (polyunsaturated, etc). Ariel. (talk) 19:57, 27 December 2010 (UTC)

What makes you feel full is bulk and weight, and fat has neither of those. Eating more fat would give you too many calories without making you feel full. If you have satisfied your hunger through eating fats, then you will have eaten far too many calories. Saturated fats, mostly of animal origin, are generally considered to be particularly bad for you. 92.24.187.63 (talk) 10:59, 28 December 2010 (UTC)

With all due respect to everyone, only a few have you have directly addressed what is different now than what existed 20 years ago. Of course eating fast food can make someone fat, but that was true back then too. And as for the argument for the internet: I find it entirely unconvincing: there were Nintendos and television back then too. And not that many people spend all day in lounging in front of the internet that wouldn't have lounged before. Magog the Ogre (talk) 21:21, 27 December 2010 (UTC)

TV and earlier video games had their effects, too, and obesity was higher 20 years ago than 100 years ago. However, TV and any particular video game each get dull after a while, while the Internet represents an almost infinite range of forms of entertainment, all available from an easy chair (that's where I am right now). They also eliminate the need to exercise in order to have social interaction, which is a big draw for teens. As for the price of fast food, it's barely changed, in dollars, over the last 30 years, despite inflation in ever other sector (except maybe electronics). A hamburger could be had for a bit under a dollar then, and it still can be, now. Meanwhile, the price of, say, a car, has gone up maybe 10x. StuRat (talk) 21:50, 27 December 2010 (UTC)

Not all high calorie foods are bad--it is only bad if you do not use the calories and they accumulate. --Chemicalinterest (talk) 21:55, 27 December 2010 (UTC)

...and whether the food also contains important nutrients or just "empty calories". StuRat (talk) 21:58, 27 December 2010 (UTC)

What makes you fat is simply: eating too much. When I visited Disney Florida (I'm South African), the servings were enormous and the Americans were polishing them off and going for dessert afterwards! Who eats a full breakfast of pancakes and sausages and then a whole cheesecake - fat people! We on the other hand, despite vagabond stares from locals, shared meals amongst ourselves and stuck to simple bread or cereal breakfasts like the way we eat at home. Another simple indicator is the amount of fries served at Macdonalds... in the USA a small fries is MUCH larger than the one they serve in Thailand... and I didn't see any fat people there (although I believe the east is heading in the wrong direction due to wetern eating influence). We do have an obesity problem here with certain sectors of the black population who eat too much phutu. It is less about the quality of food; it is the quantity. It is in local culture that says 'to be fat means I am well to do' and so they see obesity as an acceptable African culture thing. Sandman30s (talk) 12:16, 28 December 2010 (UTC)

And yet again, sandman, that doesn't address what's different now than what was 20 years ago. Nor does this anecdotal story explain why countries other than the US are getting fat at comparable levels. Magog the Ogre (talk)

The UK article you (Magog) linked to says "Scientists put the average weight rise of 7.7kg (16.9lb) down to men eating more calories and taking less physical exercise than 15 years earlier." also, specifically referring to reduced exercise in men. "The problem is really how people are getting around. They are driving more, cycling less and more likely to be employed in a sedentary job." "Physical activity is slowly being removed from day-to-day life." (Dr Peter Scarborough, senior researcher in public health at Oxford University)
I think that pretty much sums up the problem. Several factors are involved, that add up to what many would likely call 'lifestyle'. Longer working hours (likely more common than 20 years ago?) has not been mentioned so far. People who work longer hours are perhaps more likely to turn to fast food, Convenience food or TV dinner/s'microwave meals' to save time 'wasted' cooking. The ease with which a bought pre-prepared meal can be heated in a microwave oven, may be a factor that has not been fully addressed. See Fast food#Health issues, Convenience food#Nutritional issues, TV dinner#Health concerns - 220.101 talk^\Contribs 01:28, 30 December 2010 (UTC)

That is an interesting point. I hadn't thought of it. And yet, when I look at pictures of my parents 20-30 years ago, it's clear that everyone was skinnier back then. I can't possibly see how a little extra work could cause that, unless for some reason the lack of sleep is can affect weight (which I know it's done to me in the past, interestingly). Several friends and I noticed recently when we had to quit work, that we all lost several pounds, yet none of us thought we ate too much in our sedentary job. Magog the Ogre (talk) 08:28, 30 December 2010 (UTC)

There is an adenovirus (serotype 36) which may be implicated, but the shrinking middle class (growing number of people not sure how they're going to pay for the next heat and shelter payments) combined with advances in agriculture, fertilizers, irrigation, and pesticides producing an over-abundance of subsidized food for the poor is mainly to blame according to http://equalitytrust.org - do you agree? 208.54.5.50 (talk) 14:37, 30 December 2010 (UTC)

Actually Magog, there is supposed to be a strong link between staying up late (editing wp for example! ;-) ) and/or poor sleeping and weight gain! (possibly no more than scoffing bags of chips/crisps and chocolate etc. late at night. "empty calories" as StuRat said. ) I don't have a link at hand, but it is something to look into. - 220.101 talk^\Contribs 04:23, 31 December 2010 (UTC)

ps. I certainly weigh more than 20 years ago! The world population, especially in the 'developed' countries is supposed to be aging. I wonder if that factor has been allowed for? Do people tend to put on weight as they age?, I would think they would 'tend' to lose it even later in life.220.101 talk^\Contribs 04:41, 31 December 2010 (UTC)

Blister

What is the purpose of Blisters? The article doesn't say —Preceding unsigned comment added by 174.139.241.18 (talk) 14:10, 27 December 2010 (UTC)

They don't really have a purpose (eschatological rumination aside). They are an unfortunate symptom of damage to skin; they are the result of fluid pooling and becoming trapped between layers of skin. You might like to read about skin and see the diagrams in epithelium to understand the structure of human skin; you can see that if a lower layer is damaged (but an outer layer is intact), it is possible for lymph and other fluids to become trapped. Nimur (talk) 15:50, 27 December 2010 (UTC)

There is an entire class of vesiculobullous skin diseases, such as pemphigoid, in case you're interested. DRosenbach ^{(Talk | Contribs)} 17:31, 27 December 2010 (UTC)

They protect your skin from whatever caused the blister. It's like wearing padding, but the body is making its own padding. --Tango (talk) 22:11, 27 December 2010 (UTC)

No Tango, I don't think that is correct. Nimur above has pretty much explained it. Blisters are an incidental result of some sort of trauma, they occur under specific circumstances and if these circumstances are exceeded then the blister no longer protects. For example think about running in ill-fitting shoes, first you'll get a blister and then it will burst. Think about a burn, a slight burn may cause a blister but more heat will just sear the skin. What you are thinking about is a callous, a thickening of the skin developed after repeated rubbing or pressure over a sustained period. However this is more an incidental effect than any sort of 'deliberate' protection. Caesar's Daddy (talk) 08:42, 28 December 2010 (UTC)

I don't think they're "padding", but I do think the integrity of the skin on top of the fluid, as long as it lasts, protects the wound and gives it a little time to start healing before it has to deal with bacteria. By the way, callous is an adjective; you probably mean callus. Compare also mucous versus mucus and phosphorous vs phosphorus. --Trovatore (talk) 09:52, 28 December 2010 (UTC)

Well, our article agrees with me. Blister says: "This fluid cushions the tissue underneath, protecting it from further damage and allowing it to heal." (1st paragraph of "Causes" section). --Tango (talk) 16:32, 28 December 2010 (UTC)

Materialism, Reductionism and Determinism in science

Hi. I have questions about the following methodologies common in science:

Could materialism be seen as a useful way to quantificatively objectify reducible concepts within the focus of modern scientific study, rather than a systemic refutation of any possibility of an existence outside the material realm?

Could reductionism be seen as a useful way to determine the workings of each microscopic part of a larger system, rather than putting the overall holistic nature of the entire macroscopic complex system into irrelevance?

Could determinism be seen as a useful way to find a causal mechanism in retrospect of each material stage of a phenomenon, rather than a prior assumption of premediated certainty in event occurrence in a set mechanism?

Thanks. ~AH1^(TCU) 17:30, 27 December 2010 (UTC)

I think the answer to all of the above is "yes," and that such "positive" interpretations are built into the methodologies themselves. For in each of these, science recognizes that their core definitions are not necessarily known a priori. For example, with "materialism," it is true that it denies the existence of phenomena outside of the "material realm," but it has openly recognized that the definition of the "material realm" can and does change. It did not used to include such things as radio waves, for example, or dark energy, both of which have been admitted to the "material" as they became understood in terms which allow for study, replication, and etc. What is usually defined as "immaterial" are things which cannot be measured, replicated, "made reliable," etc. Science is overjoyed (in the long run, anyway) to realize that its definitions for these sorts of things are incorrect — indeed, nearly every scientific revolution has been based on such a rumbling of these sorts of foundations. (In the short run, of course, controversies are common.) --Mr.98 (talk) 17:46, 27 December 2010 (UTC)

So materialism cannot and does not, by itself, refute the possible existence of anything immaterial? In this case, is it correct to say that to do so would make the concept prove itself (self-materializing)? ~AH1^(TCU) 18:01, 27 December 2010 (UTC)

• Well, I guess it could be, but really: "In philosophy, the theory of materialism holds that the only thing that exists is matter; that all things are composed of material and all phenomena (including consciousness) are the result of material interactions."
• "Reductionism can either mean (a) an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things or (b) a philosophical position that a complex system is nothing but the sum of its parts, and that an account of it can be reduced to accounts of individual constituents." I think the position (b) is what you're questioning, right? So, just go with (a) if you want. :)
• No, strong determinism is the belief that given perfect and completely detailed knowledge of an information-closed system, the behavior of that system can be determined at and for all times. WikiDao ☯ (talk) 18:17, 27 December 2010 (UTC)

Have you read the Wikipedia articles Materialism, Reductionism and Determinism ? I think your questions "Could xxx be seen as... invite comment on what you propose as definitions of these -ism terms. None of them encapsulates The Scientific method. Instead they are selective characterisations of the Philosophy of science.

• Materialism is the attitude that matter is the primary component of reality and mind or spirit are secondary consequences. It does not "refute" the latter but takes it as axiomatic that they are products of matter acting on matter. "Quantificatively" is not an English word.
• Reductionism is the position that every concept or theory will be explicable in terms of another lower level concept or theory. The nature of a complex system is not thereby declared irrelevant, rather it is potentially fully sythesizable from the lower level theories. Your tautological adjectives "overall holistic entire macroscopic" seem equivalent to me.
• Determinism is the assumption that events are predefined with inevitable certainty in a causal chain. "Premediated" is not an English word but if you mean "premeditated", that term introduces the theological concept Predestination that is not essential to determinism. Cuddlyable3 (talk) 23:54, 27 December 2010 (UTC)

Determinism is certainly not a "useful way to find a causal mechanism", as the original poster suggested. At most, it postulates that such a mechanism exists; it doesn't help you find it.

But even that much is not clear. That sounds more like mechanism than determinism. As I understand it, determinism per se does not require that events be determined causally, but only that they be determined, period. If the future is set in stone, but not for any particular reason, that's still a deterministic situation. --Trovatore (talk) 09:58, 28 December 2010 (UTC)

And yet our article about Determinism states it is the concept that events are bound by causality and the universe is fully governed by causal laws (my bolding). Cuddlyable3 (talk) 13:11, 28 December 2010 (UTC)

Actually it says "specifically causal determinism". This is a flaw in the article, frankly. If it wants to be about causal determinism, it should be moved to causal determinism.

In somewhat contradictory mode, further down in the article, at least two non-causal (or at least not-necessarily-causal) variants of determinism are described, namely fatalism and necessitarianism. --Trovatore (talk) 18:12, 28 December 2010 (UTC)

there was blizzerd today and it looks like a very cold winter... THEREFORE THERE IS NO SUCH THING AS GLOBAL WARMING

that is what my friend says. this does not sound right to me, but I do not know how to counter his boisterous claims. What should I tell him?--Voluptuous Nature (talk) 19:06, 27 December 2010 (UTC)

Tell your friend that weather is not climate. The climate is, and has been, changing. A single weather event is exactly that. See Climate change and other articles linked therefrom, including Global warming. --LarryMac | Talk 19:10, 27 December 2010 (UTC)

but lets say there were 3 very cold winters in a row. is that weather, or is it climate? if that hapened, would it cast doubt on global warming?--Voluptuous Nature (talk) 19:13, 27 December 2010 (UTC)

Weather is local: climate is global. In individual areas, the local weather can indeed be colder under general climate change scenarios. It's worth noting that climate change research predicts an increase in intense weather activity: i.e., hurricanes/typhoons/cyclones in summer, and blizzards in winter. Winter is not going to go away, but it can get shorter, and can feature more storms - blizzards like the current U.S. East Coast storm are often the product of a collision of cold air with warm, moist air. More warm moist air + a cold boundary = snowstorm. Acroterion _(talk) 19:19, 27 December 2010 (UTC)

OK thanks. That is what I will tell my dumb friend :-D--Voluptuous Nature (talk) 19:26, 27 December 2010 (UTC)

There was an editorial in the New York Times yesterday on just this very subject. I'm no climate scientist, so I'll withhold my own judgment, but it is an interesting argument. --Mr.98 (talk) 19:46, 27 December 2010 (UTC)

If you want to impress your "dumb friend," explain to him that measuring the temperature on Earth is a very complicated process. The "Global Temperature" represents the zero-frequency component of the monopole moment of a spherical harmonic decomposition of a model of the complete global surface temperature as a function of time; and that like all planetary parameters, any effort to describe global-scale behaviors with single numbers is inevitably doomed to exclude high-frequency components (such as diurnal variations, short-duration weather phenomena, and local geographic variations). As such, a powerful and cold winter-storm that is local in geographic extent and short in duration will not be effectively captured in the "average global surface temperature," which most scientists believe has demonstrably trended towards the warmer side over the past hundred or three hundred years. Also, direct your friend to NOAA's explanation about mapping the global temperature, their global maps of ocean-temperatures, and these major research projects, NOAA Pathfinder and NASA's MODIS spacecraft instrument (we also have an article on MODIS). That spacecraft program was specifically designed for the purpose of monitoring global temperature, has flown on multiple spacecraft, and its data has been studied in great detail by thousands of scientists worldwide. In fact, you and your friend can even plot the global temperature data yourself with a variety of data-processing parameters, using NASA's online temperature plotting tool. If your friend disbelieves the data or the results, he/she can finance and launch his own global climate measurement apparatus and try to collect contrary data. Nimur (talk) 20:19, 27 December 2010 (UTC)

I think your redlink monopole moment should be a link to the article Multipole moment. But is the zero-frequency component of the harmonic decomposition any different from a simple average taken over the sampling time? I would think that near zero order components would be of more interest for extrapolating beyond the sampling time. Cuddlyable3 (talk) 19:31, 28 December 2010 (UTC)

Also note that large volumes of snow may make it look cold, but more snow actually falls when the temp is around freezing. When the temp is very cold, like in Antarctica, very little new snow falls. (Yes, there's lots of snow on the ground there, but that's because it never melts and builds up over thousands of years.) StuRat (talk) 21:41, 27 December 2010 (UTC)

If one wanted to frame the issue slightly more humorously: http://www.youtube.com/watch?v=TQlHaGhYoF0 - Jarry1250 ^{[Who? Discuss.]} 22:00, 27 December 2010 (UTC)

Climate science is at least as complicated as knowing how every detail of every component of a car works. Someone who can start the car and turn the sterring wheel is a long way from this level of understanding. HiLo48 (talk) 22:10, 27 December 2010 (UTC)

People who say this will invariably dismiss the next heatwave as merely a weather phenomenon. I'd bet your friend will do the same. Imagine Reason (talk) 14:47, 28 December 2010 (UTC)

The "warming" part of "Global Warming" is not supposed to mean that the entire earth with cook like it's in the oven. We're talking about a warming effect of a couple of degrees. In and of itself, that warming wouldn't be an issue at all, (You wouldn't notice it amid day-to-day variations in temperature.) but it's believed that by pushing the global average temperature up a couple of degrees we're going to screw up weather paterns, ocean currents, ice-caps, etc. APL (talk) 18:02, 28 December 2010 (UTC)

The nor'easter that hit the Eastern US was the December 2010 North American blizzard, and strengthened over the Gulf Stream which provided its extra boost of energy. Cold weather and extra snow do not disprove global warming any more than it supports the anthropogenic theory. See Arctic dipole. Certain mechanisms can lead to colder winters, such as intrusions of the Polar vortex due to rigid blocking patterns. Reduced Arctic sea ice from Arctic shrinkage can cause warm air to fill the Arctic in winter, forcing its coldest air over the continents where it's ususally warm. La Nina, the current phase of ENSO that we are in, typically results in warmer weather for the Southeastern United States and makes strong nor'easters such as the recent one very rare. Other factors such as a slowing of the Gulf Stream can bring colder winters to much of North America and Europe, as we have perhaps seen recently. Natural oscillations such as the North Atlantic Oscillation and Pacific-North American teleconnection pattern are also important factors. Remember that climate is a complex system that requires holistic processing (What, no article?!) to comprehend, and a small nudge in this system can have astoundingly complex outcomes. ~AH1^(TCU) 21:48, 30 December 2010 (UTC)

But if measuring the temperature of the earth is such a complicated process, how are the simple measurements from 100 years ago any good? Googlemeister (talk) 15:41, 31 December 2010 (UTC)

The instrumental temperature record itself, as well as the satellite temp record are not measuring a complex process. These only measure an average temperature of the Earth by compilation, and measurements from a century ago may well be as accurate as those today. It's the computer models that have the hard task of calculating future changes in this system, and the interactions within this system that create uncertainties. ~AH1^(TCU) 16:45, 1 January 2011 (UTC)

How many years off are we from cell phones working as well a regular phones did 40 years ago?

There is no doubt that cell phones can do things that traditional landline phones cannot. Don't get me wrong, I like my cellphone (though sometimes I worry that it gives me cancer in my private parts, but that is another question entriely).

But here's the thing.... before cell phones were invented, regular phones used to work great. You could hear the person on the other line, the call would stay connected until one of you hung up, you could go deep underground and as long as there was a phone down there, you could still hear the other person.

How far away are we from cell phones being equally reliable?--Voluptuous Nature (talk) 19:12, 27 December 2010 (UTC)

Well, the part about being underground is always going to be a sticking point; a land line phone only requires, well, a land-line to work while your cell phone requires a connection to a cellular signal, usually from a tower. I expect that we'll see a continual improvement in cell phone coverage and there will likely be some clever ways exploited to increase the penetrating power of the signals, but it's just not ever going to be as good a connection as a physically solid cord. Similar arguments take place in the popular debate over cable versus satellite television. Matt Deres (talk) 19:37, 27 December 2010 (UTC)

But could we put little cell phone node things in every wall, even undergorund, just like every wall today has an electrical outlet and these cell phone nodes would be somehow wired to actual cell phone towers. IS this a plausible idea?--Voluptuous Nature (talk) 19:49, 27 December 2010 (UTC)

WP:OR - Qualcomm, a technology company that owns/designs most of the electronics that make your cell phone work, has been investigating "micro-towers," "nano-towers", and "pico-towers," with the ultimate goal of making 100% cell-phone coverage cost-effective. The idea is to use a large tower for covering most of the city, and then using progressively smaller devices (all the way down to a "femto-tower" the size of your current 802.11 router device) to fill in any radio-shadows ("blackout areas" without coverage) - even single rooms. You can read their public white-paper, LTE Heterogeneous Networks (in reference to 3G LTE), which describes the strategic motivations and some of the technical obstacles to this development. "Since radio link performance is approaching theoretical limits with 3G Enhancements and LTE, the next performance leap in wireless networks will come from the network topology." In laymans' terms, the wireless part of the radio connection can't get any better - but we can connect up the radio-links in a more intelligent, efficient way. I wouldn't be surprised if other major wireless technology companies (at least one other) were similarly investing in this area. Nimur (talk) 20:31, 27 December 2010 (UTC)

In the UK, Vodafone offer mini cell phone towers to customers that cannot get a signal on their network. SmartSE (talk) 00:20, 28 December 2010 (UTC)

A chain is only as strong as its weakest link. Kittybrewster ☎ 20:29, 27 December 2010 (UTC)

Only if it is linear. If it is redundant, then it is much stronger than one weak link. --Mr.98 (talk) 00:29, 28 December 2010 (UTC)

I've noticed they seem more interested in pushing new features (like streaming video) than in improving basic service. I agree with the poster that I'd be much happier if I could always get a good signal, and a loud volume, than if I had games and video on my phone. One thought that comes to mind is car phones. They used to have their own antennas and could be as large as needed, but now we use our cell phones in the car instead. Why couldn't the car have a "booster" hooked up to your cell phone, with a proper antenna and power source, so you could still use it in weak signal areas ? (Using a hand's free phone, in the car, of course.) They do seem to have figured out how to plug the cell phone into the car speakers, both to mute the radio and to get a volume you can actually hear, while driving. StuRat (talk) 21:31, 27 December 2010 (UTC)

I believe the research into the use of mobiles in cars indicates that it's the conversation itself that causes the inattention to the road and consequent danger (equivalent to being drunk to some degree or other), not the use of a hand-held device. "Never use a phone when driving" is the advice that should be given, IMHO. (As is "Never use apostrophes in plurals") AndrewWTaylor (talk) 21:57, 27 December 2010 (UTC)

I was thinking it was a contraction for "hand is", as in "my hand's free". StuRat (talk) 23:21, 27 December 2010 (UTC)

To help people who can't or won't follow that good safety advice there are countries where using a hand-held phone while driving is illegal. Wikipedia has an article about that small text item. Cuddlyable3 (talk) 22:45, 27 December 2010 (UTC)

Cellular phones use radio signals. And radio is subject to interference from a variety of sources. You can improve radio transmission & reception by adding more towers, and improving the technology in cell phones for detecting weaker signals... but you'll never be as reliable as a wired telephone. There's a similar issue with computers using Ethernet cables verus WiFi signals to connect to your Internet router: the physical cable is almost always going to have a cleaner, faster signal simply because it's subject to far less interference. — The Hand That Feeds You:^Bite 22:35, 27 December 2010 (UTC)

It is almost certainly true that wireless systems will never be superior to wired systems. However, when it comes to phone technology they don't really have to be. For the purposes of the question, it is basically sufficient if the wireless system is sufficiently clear, fast, and reliable that a human being couldn't tell the difference between a wireless call and a wired one. It seems plausible that with enough cell receivers and a very robust network design, that one might achieve that someday. However, I would observe that people probably care more about the difference between "no signal" and an "okay call" than the difference between an "okay call" and a "great call". Hence cell providers probably rationally try to focus on coverage rather than quality. Dragons flight (talk) 10:29, 28 December 2010 (UTC)

I think it's safe to say never. If they would, it would have been within a decade of their widespread use. the reality is, physical limitations cannot always be overcome with technology. Plus, if you notice, the vast vast vast majority of development goes into new features that are not traditionally part of "telephone" service. Infact, i dont think voice quality has changed one bit since the introduction of 2G digital service. everything else has focused on improving data and hardware/software interface and capabilities, not the call quality at all. Roberto75780 (talk) 11:05, 28 December 2010 (UTC)

And coverage is always restricted to where the companies "think" people will be. If I had a pound for every time the phone shows "no signal" (and I mean none at all, from any of the four suppliers!) whilst I boat along the UK canals, I would be a rich man...  Ronhjones  ^(Talk) 17:29, 29 December 2010 (UTC)

Smoke when a candle blows out

I had a plain old wax candle burning cleanly and emitting virtually no visible smoke and then when I blew it out there was quite a bit. In general at a layman's level, why was there virtually no smoke during the burning and why did smoking start as the flame died? Is it because the matter that would have become visible smoke was fully reacted into an invisible product while the flame was providing energy to do so?

Candle getting blown out

Thanks. Peter Michner (talk) 20:45, 27 December 2010 (UTC)

Yes, I think that is basically correct, and see also Visible and invisible particles of combustion. WikiDao ☯ (talk) 20:53, 27 December 2010 (UTC)

(ec) Yes, that's about right. During steady state (before you blow the flame out), the flame gets its fuel from heated paraffin that evaporates, and its oxygen diffuses in from the air; but the flow of gases is laminar (smooth) and the result is a well-mixed fuel-to-oxygen ratio. When you blow out the flame, the chemical reaction doesn't stop immediately - there's a brief period of turbulence. During this time, the fuel and oxygen are not well mixed, and the result is more soot and unburned paraffin vapor. This is followed by a slow smoldering of any remnant paraffin and the evaporation of a little bit more wax (which is briefly still hot enough to vaporize, but not hot enough to combust - so it floats away as "smoke"). Those two stages are what you see as visible gray smoke in a candle. Nimur (talk) 20:56, 27 December 2010 (UTC)

You didn't ask, but the way to keep your air from being polluted with candle soot is to cover it and leave it covered. The soot will still be produced, but will deposit on the cover and candle instead of on your walls and in your lungs. StuRat (talk) 21:23, 27 December 2010 (UTC)

It's mainly (flammable) paraffin vapor. Old magic trick, blow out the candle, put a lit match in the "smoke" and the match flame "jumps" down to light the candle. PЄTЄRS J VЄСRUМВА ►TALK 21:27, 27 December 2010 (UTC)

I don't like the smoke, so I always pinch out the fire instead of blowing it out. You can lick your fingers first if you want. The smoke is mostly unburned carbon and some hydrocarbons, because the flame isn't hot enough to burn them. When it's a normal fire it's much hotter. Ariel. (talk) 21:59, 27 December 2010 (UTC)

Yeah, this is why churches and other places that use candles for light have candle snuffers for putting out the flames. Very convenient, though you have to clean the wax & soot off the inside of the snuffer bell eventually... — The Hand That Feeds You:^Bite 22:39, 27 December 2010 (UTC)

Meter

Why is a meter the distance travelled by light in 299,792,458^-1 seconds? Why didn't they just make it a clean 300,000,000? Why did they pick that value at all? —Preceding unsigned comment added by 92.251.255.12 (talk) 22:54, 27 December 2010 (UTC)

The meter already had a value. Originally it was supposed to be one ten-millionth of the distance from the equator to the pole. Later, it was standardized as the length of a particular artifact held in France. Measurements defined by artifacts are undesirable for reasons that I hope are obvious, so they found a way to get rid of them for everything except the kilogram, but they didn't want to actually change the length of a meter, or at least not by an amount that anyone would reasonably notice. --Trovatore (talk) 22:59, 27 December 2010 (UTC)

... and, in fact, the metre has never changed its size since the first (mis-)measurement. Each redefinition has just improved the accuracy with which the length can be realised in practice. Imagine the confusion a redefinition would cause with some still using the old metre and some adopting the new metre (we can't even agree on the spelling!). They picked that value because it was the average of the most accurate measurements based on the previous definition, which was in turn chosen for the same reason ... (etc.) Dbfirs 00:02, 28 December 2010 (UTC)

Wikipedia has an article about the History of the metre (spelled that way at its historical French origin in 1790). Nearly two centuries passed until the meter was re-defined in terms of time and the speed of light in space. The latter is an absolute physical constant, while time can be measured with greater precision than the inevitably uncertain duplication of mechanical standard meters. Thus the definition adopted in 1975 has the purpose of prescribing a more stable and repeatable implementation of the existing standard meter, not of substituting a different meter for the sake of getting a round number in decimal arithmetic. Cuddlyable3 (talk) 00:22, 28 December 2010 (UTC)

The original spelling was not the British "metre"; it was the French "mètre". --Anonymous, 09:09 UTC, December 28, 2010.

Well of course it does have such an article ;-) hydnjo (talk) 00:51, 28 December 2010 (UTC)

If you write metre as meter, then you are referring to a gas-meter or an electricity-meter. 92.24.187.63 (talk) 11:10, 28 December 2010 (UTC)

Er .. no. If I write "meter" I am referring to a measuring device, but it is plainly the case that many people write "meter" to refer to the unit of length so your claim is contrary to fact. --ColinFine (talk) 17:34, 31 December 2010 (UTC)

"They could round it up to 300,000,000 s^-1, but then the length of a second has to be shortened from 1 s to 0.999,308,193 s. --Plasmic Physics (talk) 11:34, 28 December 2010 (UTC)

Would that make me older? HiLo48 (talk) 11:50, 28 December 2010 (UTC)

December 28

What Makes A Human Voice Sound Male Or Female?

I was wondering what qualities a human voice possesses that make it sound male or female. If you listen to a spoken voice, you can usually tell quite easily whether it is a male or a female talking based only on the sound of the voice. But why is this? Obviously pitch has something to do with it; men's voices generally being lower than women's. But if you simply raise the pitch of a man's voice it doesn't sound like a woman's - it sounds like the same man's voice only higher-pitched. Is there some other acoustic property that differentiates male's and females voices? Thanks! Stripey the crab (talk) 03:20, 28 December 2010 (UTC)

You may be interested in Voice_therapy_(transgender) and [4]. In addition to the roughly octave difference in fundamental pitch of the sexes that you mention, there are differences in overtone production and other differences in phonation. - Nunh-huh 03:51, 28 December 2010 (UTC)

A complex sound, such as a human voice, is not a single frequency (pitch). The sound contains energy across a wide frequency spectrum, including harmonic and non-harmonic tones. Like a musical instrument, a human voice has a timbre in addition to its pitch. Usually, human speech has a large "white noise" component, usually described as the "breathy-ness" of the voice; it often has a strong impulse-signal (especially while speaking hard consonants and glottal stops; and it has a harmonic component (the vowels, and other tonal components). The human larynx is very "nonlinear", so there are also a huge amount of atonal (nonharmonic) components. Our ears are trained (and biologically predisposed) to detect certain characteristics of sound; the study of this behavior is called Psychoacoustics. It has been pretty well established that humans detect ratios of frequencies better than they detect actual absolute-frequency values themselves (generally to the discredit of the idea of "perfect pitch" musicians - they really should be called "very sensitive at detecting whether an instrument is in-tune relative to itself" or "perfect relative pitch" musicians). In other words, our ears and the brain-center that interprets signals from them are sensitive to timbre - not to pitch. Now, when you simply speed up the playback of an audio clip, you're multiplying all of the frequencies by a constant value - so the pitch changes, but the ratios (the timbre) is still the same - that's why even a high note on a bass-guitar can never sound like the same note played on flute. Nimur (talk) 12:56, 28 December 2010 (UTC)

Perfect pitch and relative pitch are different things. Relative pitch means you can hear intervals very precisely (this is necessary to sing well, for example). Perfect pitch means you can identify a pitch just by hearing it. Lots of people have good relative pitch, fewer have perfect pitch but some certainly do. --Tango (talk) 16:38, 28 December 2010 (UTC)

I've played with a program where you can speed up or slow down a sample without altering the pitch and also alter the pitch without speeding up or slowing down the sample. Increasing the pitch of my male voice would give a very good approximation of a lady's voice, I can't remember now by how much I increased it but I did try with a few other people so it wasn't just me. So I think even thought it might be a bit more complicated then that, the main factor is just pitch. Vespine (talk) 03:53, 29 December 2010 (UTC)

Ok i've just had a read of the voice therapy article and it looks like at least some of the research disagrees with me but it is not without dispute. Maybe my small sample wasn't "common" because the people I tried it with were more musical then average and not overly "masculine". But it doesn't completely refute what I observed.. Vespine (talk) 03:58, 29 December 2010 (UTC)

Kit fox or coyote?

An anonymous editor recently claimed that File:DesertKitfox.JPG is a photograph of a coyote, not a kit fox. If that claim is true, then the photo should be removed from the Kit Fox article. Can anyone confirm or refute this claim? —Bkell (talk) 05:38, 28 December 2010 (UTC)

Looks like a coyote to me. Since we have other useable image, we should switch this disputed one. Rmhermen (talk) 07:22, 28 December 2010 (UTC)

Resistricted Earth fault protection for electrical Power system

=== For High Impedence Resistricted Earth Fault protection, we provide stablizing resistance and metrosil resistors(>3kV).

The question is if the knee point voltage of the current transformer is specified as 300v then is there any chance that the voltage accross the relay terminal would increase greater than the knee point voltage of the CT. If this is not possible then why do we need a metrosil accross the relay if the source(CT) is not capable of supplying a voltage in excess of knee point voltage.???? === — Preceding unsigned comment added by Rajxananoid (talk • contribs) 08:08, 28 December 2010 (UTC)

Because the knee point voltage is not the maximum voltage, but mainly in case there was a fault, for example the source current getting coupled to the measuring current. Ariel. (talk) 09:28, 28 December 2010 (UTC)

What exactly is the "Postulate" in Newton's Laws ?

Isaac Newton was christian enough to accept whatever his external God sent down to him. Cuddlyable3 (talk) 16:14, 28 December 2010 (UTC)

I understand that to formulate a theory to describe the working of the Universe, we need a set of postulates or axiom. We can't just start from nothing, for then it wouldn't be a theory, it would just be a logical truth. Looking at Quantum Mechanics or Lagrangian mechanics, it is clear to me what exactly is "assumed" ie the postulates involved in building the theory. However, looking at Newton's Laws of motion, it's not all that apparent to me. While Newton's first law defines an "inertial system", where the second law can be applied, the second and third lawsdeal with "Force". Now, what exactly is Force ? Is Force defined to be the rate of change of momentum ? It can't be, because that would mean that's a definition and not a postulate. We already know we need a postulate ! The article on Newton's Laws brushes on this issue, but it is still not clear to me. What exactly is the postulate in Newton's Laws ? Or alternatively, what is the definition of Force ? Rkr1991 ^{(Wanna chat?)} 13:00, 28 December 2010 (UTC)

From the cited article, Newton postulated that mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities to which we can today add that his observations of these quantities failed at both sub-molecular scale and relatavistic speed. Cuddlyable3 (talk) 13:25, 28 December 2010 (UTC)

I'm sorry, but I don't understand. "Externally defined quantities". What exactly is that definition ? Rkr1991 ^{(Wanna chat?)} 13:34, 28 December 2010 (UTC)

We don't really have a better explanation than "mass is just this thing, y'know?" Mass, like certain other properties, are fundamental characteristics of matter. It happens that mass is "that property of matter that is susceptible to gravitation," and simultaneously "that property of a body that characterizes quantifies inertia." Other properties, such as position, are similarly difficult to describe. But Newton's laws explain the relationship between mass, position, and time - that mass is the constant ratio that multiplies the second-derivative of an object's position with respect to time. Similarly, we can define "force" - it's just this thing that, if scaled by mass, gives the second derivative of a body's position with respect to time. From that, we can define more sophisticated concepts about energy (or, we can start with energy as the "axiom" and derive force and position and mass). It really doesn't matter; the "equals sign" in F = ma has no preferential direction, so "ma = F" is just as good an axiom. Nimur (talk) 15:37, 28 December 2010 (UTC)

If that's the case, how come we have a clear postulate in, say, Lagrangian Mechanics ? There, we have a clearly defined quantity called Action, and a nice axiom about it. Since Lagrangian mechanics is equivalent to Newtonian mechanics, isn't it fair to expect a similar clear postulate in Newtonian Mechanics as well ? Rkr1991 ^{(Wanna chat?)} 15:59, 28 December 2010 (UTC)

Sure, but action is defined in terms of energy; and Lagrangian mechanics pretty much punts on the definition of energy. (It's just this thing, y'know, and here's an equation for it). Why is T = d/dt(dL/dqdot)? Just by definition? The formulation of Lagrangian mechanics merely expresses a relationship between energy and generalized coordinates of position and momentum (which is mathematical equivalent to F = ma); but it never explains why action should be minimized; nor why energy relates to momentum or position according to some particular formula; nor why mass exists. Those are simply mathematical abstractions of experimentally-observed reality. Nimur (talk) 18:10, 28 December 2010 (UTC)

My understanding is that the "laws" are not a theory in the sense used in the original post. They are simply a description of how the world operates. They are not an explanation of why it operates that way or much of a guess as to the underlying reasons for the behavior. Contrast this with Newton's gravitation, which postulates that there is a force called gravity (G) that, for reasons and by means Newton does not speculate on, has a predictable operation with regards to planets, solar systems, what have you. G is the postulate in that, very clearly so, and for this reason was described as "occult" by Newton's critics (it was to them as if Newton was just inventing something out of nothing without a typically Cartesian explanation of how it supposedly worked or enacted its power). Contrast this again with the kind of work done with Einstein in General Relativity, where G is replaced by the assertion that mass itself warps space. All of this is just to try and make it clear that I don't think Newton's laws are the same thing as the theories at all, which is why they are even today called "laws", which generally are just reserved for expressions of relations between entities (like Boyle's Law, which is also not a theory). The terminology is imprecise, however. --Mr.98 (talk) 16:54, 28 December 2010 (UTC)

But Newton did speculate on the means by which gravity works. In "Principia" (1687) Newton criticized the vortex model of gravity promoted by Christiaan Huygens and speculated on Mechanical explanations of gravitation such as it being "a condensation causing a flow of ether with a corresponding thinning of the ether density associated with the increased velocity of flow." but famously capitulated in the 2nd edition of "Principia" 1713 with "I have not as yet been able to discover the reason for these properties of gravity from phenomena, and Hypotheses non fingo (I do not feign hypotheses). Cuddlyable3 (talk) 18:21, 28 December 2010 (UTC)

The overall point of Newton's work on gravity though was that his postulation of a gravitational force worked, even though (as you note), he freely acknowledged he had no clue how it worked. (And while he may have speculated on its nature in a letter, it is consequential that in his widely published work, he did not.) --Mr.98 (talk) 23:36, 28 December 2010 (UTC)

@Nimur : Yes, I got your point. But just to make myself clear, I'm not asking "Why" the postulate is made. I'm merely asking "What". I understand that there is no need to answer the question "Why" as this is a postulate". The thing which is unclear to me is what exactly is that postulate. Rkr1991 ^{(Wanna chat?)} 06:06, 29 December 2010 (UTC)

I'm pretty sure the postulate is merely the Hypotheses non fingo; that is the mechanics of motion can be described without determining their root causes. --Jayron32 06:15, 29 December 2010 (UTC)

How much would it cost to invent & construct a solar wind hybrid streetlight?

Wouldn't there be an article if they exist already?

The streetlight would give energy to the grid instead of take from it. There will be a battery in the shaft of the streetlight. As a consequence, during the day, it'll be recharged to 100% and the excess gets sold back to the grid.

Because the LED streetlight will be powered by a battery all night, a solar panel will be added to the top of it in order to expedite the daytime battery recharge, and sell its excess to the grid.

While the light faces the road, there will be three wind turbines flanking it, at the height of where the light is. One on the left of the pole, one on the right, and one behind. The solar panel would be like an umbrella covering the light and turbines. (To reduce wind resistance, the panel might have to be made circular.)

Now considering the average dimensions of a streetlight that illuminates a typical boulevard,

1. How big would the three said wind turbines need to be in order to appear the correct proportions to the streetlight?
2. How many blades should it have, and what design should those blades be in order to procure the most energy out of the wind?
3. How big must this circular solar panel be in order to cover the light and turbines like an umbrella?
4. How big/tall would the battery need to be stored inside the shaft in order to provide 168 hours' worth of LED lighting without any charging input whatsoever?
5. How much would the said battery cost?
6. How many watts does a typical LED streetlight use?
7. Per 10% of power recharged to the battery, how much sunlight would the solar panel need?
8. How fast would the winds need to hit the turbines in order to cancel out the watt usage of the LED streetlight?
9. Considering the average weather patterns for the state of Kansas, how long would the said streetlight take to give a net of 1,000 KW to the grid?
10. How many KWs would it give to the grid each month? Therefore, how much money would it generate, assuming 10¢/KWh?
11. How much would a typical LED-lit boulevard streetlight cost?
12. How much would each of those said turbines cost?
13. How much would the said solar panel cost?
14. Putting labor and the cost of all these together, how long would one such streetlight take to pay for itself, assuming typical Kansan weather patterns?
15. What widely-available items can I assemble together to create a fully-working tabletop-scale model of the said power-generating streetlight?
16. How do I pitch the idea to any environmentally-inclined energy companies so that I can win a contract to get it built across many miles of roads nationwide?
17. I would like to see these streetlights light the length of all Interstate highways 5 lights to a mile, on each side. How do I make this plan follow through?
18. In order to close down all coal, other polluting, and nuclear power plants in the United States, how many of these streetlights would the nation need?
19. How many miles of four-or-more-laned roads are there, therefore, how many of these streetlights would I need per mile of these roads, in order to shut down the above-said power plants?
20. MS Paint would be a tad troublesome to draw 3D sketches. Therefore, in what free program can I draw a 3D sketch of this streetlight?
21. If I decided to add a bendable solar panel that wraps around down the full length of the pole, how much extra power could it produce in Kansan weather, how much would that panel cost, and how long would it take to pay for itself?
22. Do you have any questions?

--Let Us Update Wikipedia: Dusty Articles 14:25, 28 December 2010 (UTC)

First responses

Solar panels on street lights certainly exist (see New Jersey's program to install 200,000 on street lights and power poles[5]) Even solar/wind off-grid ones exist [6] Rmhermen (talk) 14:56, 28 December 2010 (UTC)

The big drawback with solar panels is the problem of cleaning the grime off [7]. I wonder how they're going to deal with that. (A fleet of expensive aerial work platforms using lots of energy is my assumption, or perhaps they'll just leave the panels dirty and let them operate at 20% efficiency, or use some combination of the two strategies.) 213.122.19.181 (talk) 15:12, 28 December 2010 (UTC)

This hybrid wind and solar powered lamp project was proposed in Shanghai, China. I scanned the proposal briefly; the English language grammar is atrocious, but the numbers seem very reasonable. They discuss cost and power budgets, and some competing lamp technologies. You might find it useful. Nimur (talk) 15:47, 28 December 2010 (UTC)

LUUWDA's first follow-up

RMHermen, there are some problems with that design in your link: There could be three wind turbines mounted on that pole- to the left and right of, as well as behind the light. The panel isn't large enough. One that's placed like an umbrella over all the turbines and light atop the pole would have a larger area and not be impeded by the shadow of the fan.

I suppose that the solar panel can be sloped like a cone in order to let the rainwater rinse off all the grime, therefore preclude the need for AWPs.

If I can design a model of the solar wind hybrid streetlight that will out-generate the one shown in the link, then I will give the nation and the buyers a greater edge in environmental power generation.

I see that New Jersey is already well on its way to being an environmental power producer. Great job for them! (I recommend that they still also mount wind turbines for greater effect.) --Let Us Update Wikipedia: Dusty Articles 16:12, 28 December 2010 (UTC)

Second responses

So many questions! Anyway, one I can answer is 20 - try SketchUp - it's free + reasonably easy to use. SmartSE (talk) 16:14, 28 December 2010 (UTC)

I was going to recommend Blender_(software). It's free and really hard to use, which gives a greater sense of achievement. 213.122.19.181 (talk) 16:20, 28 December 2010 (UTC)

One thought: Skip the battery. Batteries are expensive, wear out quickly, and often involve toxic chemicals/materials. Instead just sell all the energy to the grid during the day (when usage, and hence prices, are higher) and buy it back at night. One disadvantage to this is that you lose the "battery back-up". That is, if the grid goes down, so do your streetlights. However, streetlights aren't absolutely necessary, as cars have headlights, so we could get by without them during an outage. StuRat (talk) 16:32, 28 December 2010 (UTC)

The more heavy (and wind-catching) things you stick up the pole, the stronger the pole needs to be, and soon it will become like a pylon and cost a lot, cast a big shadow, and get in the way. Streetlight#Dangers speaks darkly of metal fatigue and damage from high winds. 213.122.19.181 (talk) 16:48, 28 December 2010 (UTC)

Yes, and windmills make noise, have moving parts that require maintenance, can have pieces fall off, say in a hurricane, to create dangerous flying debris, etc. Perhaps just a cylinder of solar cells around the pole might be best (or just on the side facing the Sun). I wonder if solar cells could be created in a saw tooth fashion like this:

     /|     |\
      |  P  |
     /|  O  |\
      |  L  |
     /|  E  |\
      |     |

The angled bits would be the solar cells. StuRat (talk) 17:27, 28 December 2010 (UTC)

That's a nice design. It could probably get wider lower down, where the extra bulk won't affect stability so much, tapering to a point at the top, although perhaps with a bare section right at the very base, to allow people to walk past it. 213.122.36.99 (talk) 18:38, 28 December 2010 (UTC)

1. 2. 8. See the article Wind turbine for ideas.
4. See the article Rechargeable battery for types and their energy densities.
9. 10 KW is a unit of power that makes no sense in these questions "how long would it take?" KWh is the saleable quantity.
15. One can buy small garden lamps that comprise LED's, a battery and a solar cell for daytime charging.
16. See the article Business case. But first find an "environmentally-inclined energy company" with an oversized PR budget.
17. This is one way.
18. 19. More than a few.
20. See 3D computer graphics software#Free packages. Cuddlyable3 (talk) 18:58, 28 December 2010 (UTC)

For a bit of progress with 18 and 19, there's electricity consumption, which gives 14,378 kWh per person. The 2010 figure for US population is 308,745,538, so that makes 4,439,143,345,364 as a figure pending translation into a number of streetlights. Oh, minus 9.5% that comes from renewable energy already. So only 4017424727554.42 kWh needed. Much easier. 213.122.36.99 (talk) 19:14, 28 December 2010 (UTC)

LUUWDA's second follow-up

To StuRat

StuRat, excellent ASCII sketch! I could put that in, along with the turbines and "panel umbrella" (but as long as that "umbrella" doesn't shade the other pole-mounted panel.)

To keep high winds from snapping off the wind turbine blades, they can be kept inside "cages" that surround all sides of the blades with some type of grating, so whenever anything falls off, it stays inside the said grating and does not cause a hazard below. To perform any needed maintenance, the utility worker would just need to unlock the grating with a skeleton key and open it like a door.

Thanks. I thought a bit more on it, and decided that a long, flexible spiral would be easiest to apply to existing utility poles, using suitable adhesives. Here's a revised diagram:

      |     |\
     /|  P  |
      |  O  |\
     /|  L  |
      |  E  |\
     /|     |

StuRat (talk) 06:55, 29 December 2010 (UTC)

To Cuddlyable3

9: Yes, how long would it take for one such solar wind hybrid streetlight to generate 10 KW of energy? If this doesn't make sense to you, would it to anyone else? Could they answer it?

15: Now how about miniature wind turbines? What can I get to make the miniature turbine parts, and where?

18 & 19: Yes, but is anyone able to do the math and get me a numerical approximation?

Thanks for the other tips though.

To 213.122.36.99

Thanks, so how many of these said solar wind hybrid streetlights would need to light our roads to provide 4.02 petawatt-hours of power?

Therefore, if we decided to light even the paved two-lane roads as well as all the roads with more lanes in the United States, how many of these streetlights would we need for every mile of these roads? --Let Us Update Wikipedia: Dusty Articles 04:49, 29 December 2010 (UTC)

213.122.18.78's/213.122.36.99's Follow-up

The CIA World Factbook [[8]] gives 6,506,204 km of US roads, paved and unpaved. (Not sure if this exactly congruent with "suitable for street lighting", but at least we're not discussing coastline lengths.) So that means ... wait, how much power does each one of your lamps generate? I think I missed that. Anyway 4017424727554 (kWh) / 6506204000 (m) makes about 617.476 kWh that each metre of road has to generate (per year, I assume). This site [9] claims "A rotor diameter of 2 metres might yield about 500 kWh of electricity per year". I'm not sure what that site is, but it seems likely that they want to sell you turbines, and therefore have made optimistic estimates of turbine power based on a turbine on top of a hill. So (assuming no order-of-magnitude errors in my various sums and guesses), if you have two-metre wide rotors spaced one metre apart on every road in the US, I think you will fall somewhat short of generating enough power. (For heartwarming tales of improvised wind turbines, see William Kamkwamba.) 213.122.18.78 (talk) 09:37, 29 December 2010 (UTC)

LUUWDA's response to the IP user

That is for one rotor of wind turbine. Each streetlight in my design has 3, plus a solar panel umbrella atop them all, and as suggested by StuRat, down the shaft of the pole.

That means more than 3 meters apart from one another, but thanks to variables in the availability of wind & solar power, let's just make them 3 meters apart, assuming 500 kWh/year per rotor. (I am unsure how many square feet of solar paneling each streetlight will have, and therefore how many kWh/year they will generate.)

Then two of these streetlights would face each other from their shoulders, so that means we just need these streetlights 6 meters apart from one another.

Also consider the fact that some medians of boulevards and highways are also equipped with lightposts in the center. Since this means two lights have to shine on both sides of the road, there can only be two wind rotors. There will still be the solar panels though.

Once you factor the median lights in, how many streetlights per mile (or kilometer) do we need after all? --Let Us Update Wikipedia: Dusty Articles 13:03, 29 December 2010 (UTC)

If the three rotors face in different directions, that doesn't mean they'll produce three times the power, since the wind only blows in one direction at a time. Windmills usually turn to face the wind. There's also the nifty vertical-axis option: Wind_turbine#Vertical_axis_design. (The Panemone WECS, on the other hand, is slated as "one of the least efficient types of wind turbine", so don't use one of those.) If the three rotors face in the same direction, close together, one behind the next, that configuration won't produce three times the power either. I'm not sure exactly what happens, but the rotor in front is going to disrupt things for the rotors behind. 213.122.0.247 (talk) 18:06, 29 December 2010 (UTC)

Fox barks

What does British fox barking sound like, and how can it be differentiated from dog barks? Thanks 92.29.118.30 (talk) 15:21, 28 December 2010 (UTC)

Well they kind of cough and yip, a bit higher and harsher than a dog. Also they're slightly more restrained and won't bark continuously for ages. Some recordings here: [10] I tried the one from Woking, sounds like a fox to me. They also make some very unsettling screaming noises when fighting or mating (which they seem to like to do under my bedroom window in summer). 213.122.19.181 (talk) 15:30, 28 December 2010 (UTC)

The recording called "foxesbymoonlight" on the same site is the sound that I associate with winter and vixens calling looking for a mate. Richard Avery (talk) 19:43, 28 December 2010 (UTC)

I ask because I heard something that may or may not have been a male fox - a somewhat high pitched single rather long bark, then quite a long pause, then this single bark followed by a pause being repeated several times. It was in a wooded area in a suburb - I'm not sure if there is a house inside the wood or not. 92.15.14.203 (talk) 20:36, 28 December 2010 (UTC)

Another suspect might be the Muntjac which sounds a bit like a dog with a sore throat. They're increasingly common in woodland in the South East and Midlands. Alansplodge (talk) 00:08, 29 December 2010 (UTC)

Very good point, I now recall seeing somewhere else in the past a small deer - probably a muntjac - that barked while I was watching it, and my hazy memory suggests it was similar, although it did not do the long regular series of barks I heard above, probably because it had been disturbed by me. So I conclude that what I heard was probably a muntjac. 92.29.120.235 (talk) 12:56, 29 December 2010 (UTC)

Using spy satellite film to take pictures on the ground

I recall reading an article, maybe 5 years ago (that's a big approximation, I don't remember when it was), about someone designing a camera that took old film, intended for early spy satellites, and took high resolution pictures from the ground with it. I think I read about it in Discover (magazine), though it might have been Popular Science or something else entirely. I'm pretty sure it was a magazine I read it in, though. I recall that while the camera used film, they converted it to a digital file, rather than just print a huge picture. The example picture that was taken was of a beach scene. I remember that they had blown a section of the picture up, and found a couple of guys taking photos of the women on the beach with telephoto lenses from a bluff overlooking the beach. My Google skills are failing me; does anyone recall this article, or know what I'm talking about? Buddy431 (talk) 15:58, 28 December 2010 (UTC)

"The Sharpest Image," Popular Science, November 2005. —Bkell (talk) 16:44, 28 December 2010 (UTC)

Thank you so much. Buddy431 (talk) 17:06, 28 December 2010 (UTC)

Peripherally related spy-camera note: the BBC is running a documentary this week called Polar Bear: Spy on The Ice - you can see videos of the "spy-cameras" they used to film bears in their habitat in Norway here: 'Spy cams' film polar bears up close and Polar bears get the better of spy cameras. The only difference between a ground- and satellite- spy camera is where it is; satellite cameras might use different lenses (or mirrors), different film formats, or lower ISO film (nowadays, radiation-tolerant CMOS or CCD sensors), in order to facilitate long-range imaging from orbit. They might have been specially engineered for small form-factor or other flight characteristics. But otherwise, they need not be any different from a ground-camera. Nimur (talk) 13:32, 29 December 2010 (UTC)

What does this mean?

What does "mildly discoid medial meniscus with accompanying myxoid degeneration" mean? 74.198.151.76 (talk) 18:30, 28 December 2010 (UTC)

Here's discoid meniscus, which has a picture labeling the medial meniscus. In my capacity as not a doctor, I think "accompanying myxoid degeneration" means it's gone all slimy. definition of myxoid 213.122.36.99 (talk) 18:50, 28 December 2010 (UTC)

Density

So why hasn't the definition of density changed to be more accurate as to what density actually measures? Since the volume of one atom times 1,000,000 will be different than the volume of 1,000,000 atoms in a cluster? —Preceding unsigned comment added by 165.212.189.187 (talk) 20:11, 28 December 2010 (UTC)

"density of a material is defined as its mass per unit volume. " That seems pretty straightforward to me. As true today as the day it was written. I don't understand your point about atoms. APL (talk) 20:34, 28 December 2010 (UTC)

The unit you are looking for is called the Molar concentration. Ariel. (talk) 20:36, 28 December 2010 (UTC)

No. If there is "free space" among (on the "inside") 1,000,000 atoms in a cluster of a particular substance and we attempt to measure the density (mass/volume) we are incorrectly including the free space between those atoms as part of the volume. Conversely, if we attempt to measure the volume of one of those atoms we would not be including any any of that same free space as there is only one atom. Get it? —Preceding unsigned comment added by 165.212.189.187 (talk) 21:05, 28 December 2010 (UTC)

What possible value would such a measurement have?

Besides, the fundamental particles seem to be points. In which case your way of measuring volume would just give you a "divide by zero" every time. APL (talk) 21:08, 28 December 2010 (UTC)

Volume and density are clearly defined on a macro-scale. On a sub-atomic scale, all space can be viewed as either full or empty, depending on your view. Volume, mass and density have no meaning at lowest level (where there is no mass, only energy, (depending on your viewpoint)). Dbfirs 21:39, 28 December 2010 (UTC)

APL, exactly my point. —Preceding unsigned comment added by 165.212.189.187 (talk) 20:16, 29 December 2010 (UTC)

Alternatively, the probability distribution waveform of any particle is distributed throughout all space, so everything would have zero density by this (silly) analysis. There was a discussion a few days ago: Wikipedia:Reference_desk/Archives/Science/2010_December_22#Space_between_particles Dbfirs 10:34, 30 December 2010 (UTC)

... though if you integrate the product of particle mass and the probability distribution waveform over any conventionally defined volume, and add for all particles conventionally regarded as within the volume, the result will be conventional density to a very high accuracy. Dbfirs 11:21, 30 December 2010 (UTC)

rubber cement

how stong is rubber cement compared to liquid nails —Preceding unsigned comment added by 66.66.92.152 (talk) 20:13, 28 December 2010 (UTC)

Different glues work best on different materials. A good glue is stronger than the material it's glued to, anything more is pointless, and anything less is not a good glue. (But stress concentration explains why things will often re-fail at the glue point, even if the glue is strong enough.) Ariel. (talk) 20:39, 28 December 2010 (UTC)

In my experience "No More Nails" would be very much stronger than rubber cement or "cow gum" as it is also known. The rubber cement is for sticking paper. I stuck some wood to plaster with NMN, and when I prized it off it was the plaster that broke off, not the NMN. I assume "Liquid Nails" is the same as NMN. NMN is not flexible, rubber cement is. 92.15.14.203 (talk) 20:42, 28 December 2010 (UTC)

Yes, the problem with "liquid nails", "no more nails" etc is not the strength of the glue but the problem of getting a good bond with both materials. For some surfaces, especially flexible materials, rubber cement will form a stronger bond, so will serve its purpose better even though the glue itself might be weaker. Dbfirs 21:31, 28 December 2010 (UTC)

Brie cheese

OK, I've been wondering this for a while now. Why does brie cheese smell like semen? THis may sound crass but it is out of genuine curiosity that I ask this, and so I'm looking for a genuine, scientific answer. Thank you. 24.92.70.160 (talk) 20:39, 28 December 2010 (UTC)

Smell is a bit subjective, but the odor of Brie (indeed of all cheeses) is due to the particular cheese cultures used to make the cheese. The article Brie covers some of the specifics of manufacture, but the mold used to culture and flavor brie is Penicillium candidum. --Jayron32 21:07, 28 December 2010 (UTC)

Saliva

Why does saliva get foamy when you spit? ScienceApe (talk) 21:28, 28 December 2010 (UTC)

Proteins in the saliva provide a medium in which to form bubbles. Its the same reason why whipped eggs form foams (soufflé or meringue), or why sea foam forms. --Jayron32 21:37, 28 December 2010 (UTC)

Clover

Why don't humans eat clover? – Athaenara ✉ 22:48, 28 December 2010 (UTC)

Some humans do eat clover: http://www.associatedcontent.com/article/2851188/cooking_fried_white_clover_blossoms.html?cat=57 (damn spam filter). Search "fried clover" or "eating clover" in your favorite search engine to find many more examples. Buddy431 (talk) 23:10, 28 December 2010 (UTC)

Trifolium repens discusses some of the culinary uses of that species; Trifolium pratense points out that this particular species does have estrogen-like compounds which makes it troublesome for some people. General notes seem to be that it is hard to digest raw. --Mr.98 (talk) 23:50, 28 December 2010 (UTC)

Which might explain why we eat it indirectly, such as in the form of clover honey. StuRat (talk) 00:45, 29 December 2010 (UTC)

Fenugreek (not in the clover genus, Trifolium, but in a related genus, Trigonella) is eaten in various forms in many cultures. --Dr Dima (talk) 00:09, 30 December 2010 (UTC)

They don't have any crimson to go with it? --Trovatore (talk) 03:04, 30 December 2010 (UTC)

A clover flower.

More seriously, I seem to remember that as kids we used to pluck the clover flower, and suck the nectar out from the stem. I don't see any mention of that in any of the articles named above. --Trovatore (talk) 03:11, 30 December 2010 (UTC)

Could you be thinking of honeysuckle, Trov? WikiDao ☯ (talk) 03:20, 30 December 2010 (UTC)

No, I'm pretty sure it was clover. --Trovatore (talk) 03:28, 30 December 2010 (UTC)

Because that's a very common thing to do with honeysuckle. I don't see how one could do that with a clover flower. WikiDao ☯ (talk) 03:35, 30 December 2010 (UTC)

You just pinch off the flower, put your mouth on the green part, and suck. It isn't complicated. No guarantees though -- I think the last time I tried this, I might have been four. --Trovatore (talk) 03:55, 30 December 2010 (UTC)

Yes, that is a very young age from which to retain an accurate memory... WikiDao ☯ (talk) 04:03, 30 December 2010 (UTC)

Nevertheless I believe it was in fact an accurate memory. --Trovatore (talk) 04:04, 30 December 2010 (UTC)

Okey-doke. If you say so. Come spring-time, we'll have to give both a try and see which works. :) WikiDao ☯ (talk) 04:09, 30 December 2010 (UTC)

Video on how to eat honeysuckle nectar: [11]

Can't seem to find one on how to eat clover nectar (at least, without using a proboscis...). WikiDao ☯ (talk) 04:36, 30 December 2010 (UTC)

I do not see why you are so skeptical about this. Clover is well-known as a source of nectar. Why shouldn't it come out the base, if you suck on it? As for honeysuckle, it has never been common in any place I have ever lived. --Trovatore (talk) 04:40, 30 December 2010 (UTC)

I have never, in my experience, sucked nectar from clover, nor ever seen anyone else do so. Sucking the nectar from honeysuckle I have done many times, and seen others do many times, too. My experience of this is from Virginia to Vermont, and once or twice even somewhere in the midwest. So at this point, I'd like to see an RS for sucking clover nectar, especially if, as Sluzzelin seems to have thought[12], doing that might be "hazardous". WikiDao ☯ (talk) 04:50, 30 December 2010 (UTC)

Well, the "hazardous" thing is a bit overwrought in my opinion. Someone brought up that clover has phytoestrogens, and in unusual circumstances those can be harmful, but a lot of things have phytoestrogens. And of course as always, it's hard to know what might have been sprayed on (or peed on, or crapped on) a patch of grass not under your control, but there could be similar issues with honeysuckle.

As for a reference, Sluzzelin apparently gave you one (though I haven't yet followed the link). --Trovatore (talk) 05:11, 30 December 2010 (UTC)

Yes, sucking the nectar from individual white clover flowers is as well-known in the UK as making daisy chains: it's something children will generally try when lounging on a lawn full of them. You can also do it with the flowers from dead nettles, Adam and Eve plant, and the plant I always forget the name of that is a bit like ivy (to a child) and has purple and white varigated flowers that have a cone at the base and then spread in a flat circle. Anyway, I don't know where you got the idea this only works with honeysuckle: white clover was always the featured flower when children did this in my books, but I had more success with a variety of others. I was often scolded for deflowering an entire plant to suck its nectar ;) 86.164.67.8 (talk) 09:00, 30 December 2010 (UTC)

would using and electric welder demagnetise a rare earth magnet

I have a Magneto with rare earth magnets fitted to my classic motorcycle, I have recently welded a compounent to the chassis of the machine but forgot to remove/disconect the Magneto whilst doing the repair.Would this have had an effect on the magnets within the Magneto. (de-magnetised) . —Preceding unsigned comment added by 86.11.245.195 (talk) 23:23, 28 December 2010 (UTC)

Rare earth magnets have a high resistance to demagnetization, unlike ferrous magnets they shouldn't demagnetize in the presence of other magnetic fields. Rare earth however magnets will still demagnetize if they are heated past a certain point, for common N type magnets this starts at a relatively low temp of about 80 deg C. If you didn't heat the magnets with the welding, but are just worried about the magnetic fields then you should be ok. Of course, this is just my opinion and it could be wrong. If the magnets aren't rare earth, or if they did manage to heat up, also depends on what kind of welding you used, some welding creates much higher magnetic fields then others. In the end, you'll probably still need to test the magneto to see if it is working correctly. Vespine (talk) 01:08, 29 December 2010 (UTC)

The easiest way to test it would be to start up the motorcycle. PhGustaf (talk) 03:57, 29 December 2010 (UTC)

December 29

what makes tuning fork prongs oscillate oppositely?

I really like this answer: http://in.answers.yahoo.com/question/index?qid=20100308050035AArgLTA But I don't get one thing. What ensures that the two prongs will oscillate in an exactly inverse way? Naively, I'd think the chances of that happening by chance are infitessimal compared with the chances of their not oscillating at just inverse frequencies when struck.... 87.91.6.33 (talk) 02:11, 29 December 2010 (UTC)

p.s. am I also riht that the fork could just as easily have 4, 6, 8, or 12 prongs? In this case, half of the prongs would oscillate one way and half the other??? (inverse frequency) what ensures this?? 87.91.6.33 (talk) 02:11, 29 December 2010 (UTC)

For the 1st question, my guess is that the "handle" creates a node. This explains why the two prongs oscillate in opposite directions, because they are really one bent prong with a handle in the middle. Not sure about more then 2 forks, I suppose it's possible but would depend on specifically how it is designed. Vespine (talk) 03:34, 29 December 2010 (UTC)

If they didn't start out synchronized, they will rapidly synchronize themself. Watch some of these videos for some examples. Ariel. (talk) 06:41, 29 December 2010 (UTC)

I think the answer to this is quite simple: the tuning fork starts out in some combination of equal-phase and opposite-phase vibration, but the equal-phase part is quickly damped out by the mechanism described by that Yahoo answerer. You'll always end up with mirror-symmetric oscillation eventually as long as a mirror-symmetric oscillation mode exists and you started out with at least some energy in that mode. I see no reason why it couldn't also work with 3, 5, ... prongs, since those shapes can oscillate symmetrically too. The oddly titled article Odd sympathy discusses this. I'm not sure I understand what happens to the metronomes on the soda cans, but I think it's somewhat different. -- BenRG (talk) 11:32, 29 December 2010 (UTC)

The modal analysis article is worth linking. Nimur (talk) 14:19, 29 December 2010 (UTC)

Why do we fear or 'over react' when something falls from our hand?

Why do we fear or 'over-react' when something falls from our hand (accidentally)? - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 04:43, 29 December 2010 (UTC)

Because we'd rather it didn't break when it hits the floor? --Jayron32 04:44, 29 December 2010 (UTC)

I once read that when a woman drops something she tends to throw her hands back and step back, as if avoiding anything further to do with the falling object at that moment, while a man will use all his limbs in a seemingly desperate attempt to slow the object in its fall to the floor. Some random original research would seem to support that view, but I have no idea if it's more broadly true. HiLo48 (talk) 05:48, 29 December 2010 (UTC)

I suspect whoever wrote that was completely making things up, either based on a small selection of people they had known to drop things, or just because it matched how they thought the world worked. It doesn't fit with any of my personal experience or observations, nor does it seem at all consistent with anything I have read on the actual science of gender differences. Did you, perhaps, read it in a fiction book? 86.164.67.8 (talk) 17:41, 29 December 2010 (UTC)

Not just breakables. We do have a jerk when things slip out of our hands. —Preceding unsigned comment added by 125.21.50.214 (talk) 05:50, 29 December 2010 (UTC)

It probably has something to do with dropping babies. Sean.hoyland - talk 12:16, 29 December 2010 (UTC)

It may be a counterpart to an impulse a highly developed capacity to grasp. The hands are used to hold onto something, and they do that under a wide variety of circumstances and over extended periods of time. The hands of humans are very well developed in this area and there is probably complex mental functioning supporting the grasping functions of the hands. The realization that there is a failure in that function probably causes complex mental reactions. Somehow, I would guess, that leads to overreaction, or fear. Bus stop (talk) 12:25, 29 December 2010 (UTC)

The answer to this, I think, is actually quite complex. The mechanism is actually a way of speeding reaction times, but the way we perceive it is shaped by some special brain mechanisms. Some of the factors that come into play are discussed in the article Neuroscience of free will, especially the section relating to reaction times. Looie496 (talk) 16:36, 29 December 2010 (UTC)

What kind of holly?

The holly and the icy

What kind of holly is this? I never realised that there were multiple holly species until this evening, when I discovered that there were lots of different categories at Commons for different species of holly. Nyttend (talk) 05:04, 29 December 2010 (UTC)

I'm not sure we can tell from that one picture. There are literally hundreds of different species and/or hybrids of Holly, and many are likely to be indistinguishable execpt by careful, direct, examination by a knowledgeable botanist. See Holly#Selected_species for an idea of the problem. Browsing through several of these that have pictures in the articles, I can't find much to distinguish them either from each other, or from your picture. --Jayron32 05:17, 29 December 2010 (UTC)

Hmm. Sorry to have asked an unanswerable question; thanks for trying. Nyttend (talk) 16:16, 29 December 2010 (UTC)

Dark energy and antimatter

Hello. Is antimatter attracted or repelled by dark energy? Is there anything in the universe which is attracted by dark energy? Thanks in advance.--Leptictidium (mt) 11:32, 29 December 2010 (UTC)

Dark matter interacts with other matter (including antimatter) gravitationally. This interaction is always attractive. --Wrongfilter (talk) 12:58, 29 December 2010 (UTC)

Dark energy (not dark matter) is basically another way of looking at the metric expansion of space. As such, it's a property of the vacuum, rather than something to do with matter, so normal matter vs. antimatter is irrelevant.

The consensus among physicists is that the gravitational interaction of antimatter is attractive, although that hasn't actually been experimentally confirmed yet. But again, that's actually irrelevant to a discussion of dark energy. Red Act (talk) 14:46, 29 December 2010 (UTC)

Oh dear. Sorry, I misread. --Wrongfilter (talk) 15:02, 29 December 2010 (UTC)

I'd like to add that it is unknown whether or not dark energy is a property of the vacuum. That is a leading theory, but alternative theories (such as quintessence) would allow the repulsive effects of dark energy to be associated with some new type of particle. Since we don't really understand what causes dark energy, it is safe to say that there are lots of possible explanations. Some are more plausible than others. Dragons flight (talk) 18:34, 29 December 2010 (UTC)

How much damage would a missile do?

Let's say a Hsiung Feng IIE missile was fired into the middle of Central, Hong Kong at rush hour. How much damage would it do? How big would the crater be? How many people would it kill? (A dozen? Hundreds?) 122.61.218.145 (talk) 12:04, 29 December 2010 (UTC)

It depends very much on the actual warhead. With a dead weight, maybe around a dozen. With a HE warhead, I'd guess hundreds. In both cases, there would be a very large spread of possible outcomes. If you assume WMD loads, the numbers can become much higher. --Stephan Schulz (talk) 14:02, 29 December 2010 (UTC)

With due respect, the OP's scenario is worrying about cruise-missile targeting from the vantage point of "concerned citizen," and not from that of a "geopolitical strategist." Most reliable references on the strategic implications of cruise-missiles focus on their cost-benefit analysis; and most rational strategists would opt to target airports and air-bases, not busy city streets. Cruise Missile Proliferation in the 1990s discusses details and specifications some of the various missile capabilities known to exist in various countries. The Cruise Missile Challenge, a policy report published by independent agency CSBA, gives a good overview of cruise missile politics, cost, and even discusses their potential strategic use in the Taiwan Strait conflict. Bear in mind, cruise missiles are really expensive - and Taiwan doesn't have many of them; so strategically, the most significant targets for them would be military airfields (where a single strike could incapacitate hundreds of millions of dollars of enemy aircraft). Airbase vulnerability to conventional cruise-missile and ballistic-missile attacks, published by the infamous RAND Corporation, provides a stunningly (and frighteningly) detailed scenario of potential damage (and vulnerability of) an American air-base to an enemy cruise-missile attack; and it lays out the cost-benefit analysis of strategic and tactical missile strikes. Regarding blast range, collateral damage, casualties, and targeting effectiveness, of course that sort of detail would be highly confidential; but you can easily estimate the power of a 200 kg warhead and the probability of landing on a crowd of any particular density of people-per-square-meter. (But you can see maps, diagrams, and blast-radii in that altogether terrifyingly descriptive RAND book). Ultimately, keep in mind that military use of cruise-missiles against civilian targets is both expensive and geopolitically stupid - the world does not look kindly on the use of powerful technological weaponry against civilian targets. Taiwan would be unwise to expend its very limited stockpile of tactical or strategic missiles against a civilian target; each missile fired at a civilian target would clearly aggravate their adversary; and simultaneously, it would do little to impede the Chinese military capability for retaliation. Nimur (talk) 14:10, 29 December 2010 (UTC)

Also, deliberately attacking the civilians of your enemy is prohibited by the Fourth Geneva Convention (1949). You can, say, attack the Ministry of War's building, even if doing so will cause civilian casualties, but you can't launch attach that will solely cause civilian deaths. CS Miller (talk) 15:29, 29 December 2010 (UTC)

When was the last time a world-class business city was attacked by a state's armed forces using big-enough-weapons? The city must be a key player in international business (e.g., NY, London, Tokyo, HK ...). Did it ever happen after WW2? The Chinese civil war (-1949) was not a war between two countries. Berlin was only denied land-based access by the Soviets. Seoul was not an international business city at the time of Korean war. 1950s and 1960s Saigon might have been a large city however Vietnam as a French colony was not very "international". Beirut has always been a regional city. The 9/11 attack was not ordered by any country. Baghdad certainly was not very international. -- Toytoy (talk) 18:12, 29 December 2010 (UTC)

What's a 'world-class business city' ? Sean.hoyland - talk 18:15, 29 December 2010 (UTC)

I can't define it. However, it must have a certain percentage of investments from many major 1st world countries. As a result, if you attack this city, investors could get very angry at you. You not only make the victim country very angry, but you also make many other 1st world countries very very unhappy. Let's say I bombed a small town in Kansas. People around the world may never heard of that town (population 32). They do not get very angry. But if I bombed London or Paris, people all over the world knew the city, many people have money in these cities, they get very very very angry. -- Toytoy (talk) 18:21, 29 December 2010 (UTC)

I asked because 'When was the last time a world-class business city was attacked by a state's armed forces using big-enough-weapons?' is quite an interesting question that I don't know the answer to....um...Kuwait City, Belgrade...maybe...I'm struggling. Sean.hoyland - talk 18:35, 29 December 2010 (UTC)

The Hsiung Feng IIE's modern 200 kg high explosive payload might be roughly comparable to the WW2-era 980 kg Amatol payload of the German V-2 missile. The worst loss of life in a single V-2 attack was 160 killed and 108 seriously injured and a modern reconstruction (see article) demonstrated that the V2 creates a crater 20 m wide and 8 m deep. Cuddlyable3 (talk) 22:19, 29 December 2010 (UTC)

Elipitical Orbit

I would like to know whether the orbit of a planet/satellite become an elipitical orbit if its tangential velocity is reduced or increased beyond the confines of a circular orbit. References preferable. --Tyw7  (☎ Contact me! • Contributions)   Changing the world one edit at a time! 12:35, 29 December 2010 (UTC)

Yes it does (in both cases), at least as long as an increase in velocity is not so large as to make the orbit unbound (i.e. parabolic or hyperbolic). In the spherically symmetric gravitational field of the central body any (bound) orbit is periodic, i.e. the satellite has to return to its original position. If you decrease the velocity, that point will become the apocenter (i.e. the point farthest from the central body) of the elliptical orbit, if you increase the velocity it will become the pericenter. --Wrongfilter (talk) 12:57, 29 December 2010 (UTC)

Regarding references: I highly recommend the book To Rise From Earth, which provides a straightforward explanation of orbital mechanics that is accessible to any interested reader (even if they don't have a firm background beyond basic algebra). This book is intended to introduce the concepts and basic mathematics of spaceflight without requiring a full-blown degree in astronautics. It is suitable for anyone with at least a junior-high or high-school level of algebra, and claims to use "no equations" to describe orbital mechanics (though I seem to recall a few). There are also plenty of textbooks that study this subject in greater details, if you do have at least some background in basic calculus and physics. And if you are interested in professional grade space navigation, NASA provides DESCANSO, a compendium website of educational and technical resources, including free textbooks, for Deep Space Communications and Navigation systems that will hold nothing back on the "details." (After all, if you want to point your communications antenna at an interplanetary probe, you had better calculate its orbit exactly - no "approximations"). Nimur (talk) 13:41, 29 December 2010 (UTC)

Does cancer cause hair to fall out?

Or does the treatment like chemo cause the hair to fall out? ScienceApe (talk) 18:34, 29 December 2010 (UTC)

Chemotherapy is what causes it to fall out. thx1138 (talk) 18:41, 29 December 2010 (UTC)

Radiotherapy and many (but not all) forms of chemotherapy rely on the greater susceptibility of rapidly dividing cells to DNA damage. While the malignant cells targeted by these therapies certainly fit the bill, there are a few other places in the body where normal cells divide rapidly; it is the sensitivity of these tissues that often establishes the maximum tolerable dose for these therapies, and which is responsible for many of the side effects associated with these treatments. Quickly dividing cells in bone marrow, the lining of the gastrointestinal tract, and in hair follicles are all sensitive to DNA-damaging treatments, leading to (respectively) anemia, (some of the) nausea, and hair loss associated with certain types of cancer treatment. With radiation therapy, hair loss will only occur within the areas exposed to ionizing radiation; with systemic chemotherapy hair loss can be widespread. TenOfAllTrades(talk) 19:39, 29 December 2010 (UTC)

Animal slime?

With regards to the slime secreted by slugs/snails, frogs, fish, eels, etc. - is it all the same basic stuff, regardless of the creature that secreted it (I guess that some animals can add toxins and irritants to it)? If so, is there a an easily writeable chemical formula for this substance? --95.148.109.133 (talk) 18:54, 29 December 2010 (UTC)

The technical term is mucus, and as that article tells you, the most important components are a variety of proteins. Looie496 (talk) 19:02, 29 December 2010 (UTC)

Many animals can make mucus including some single cell protists. Glycoproteins are abundant. Graeme Bartlett (talk) 20:13, 29 December 2010 (UTC)

Intelligence of a sleeping human

How intelligent is someone who's asleep, but not dreaming? While I'm at it, what about animals? — DanielLC 20:48, 29 December 2010 (UTC)

That's kinda like asking "What is the blood type of someone who's asleep". Even ignoring the fact that "intelligence" is a nebulous, unmeasurable quality to begin with. So, insofar as someone has a measurable thing called "intelligence" at all, it shouldn't be different just because they are asleep. Since someone cannot take an intelligence test while asleep (indeed, one cannot take any test while asleep) it seems a silly proposition to begin with. Animal intelligence is even more difficult to assess; we can measure animals on their ability to perform certain tasks (such as run through mazes or pfoint at pictures to get food), but exactly how or why these tasks might indicate "intelligence" is pretty difficult to assess. --Jayron32 20:56, 29 December 2010 (UTC)

You can still respond to stimuli while asleep. You can't take an IQ test, but neither can any animal except a human. Can't they still test your intelligence the same way they test that of an animal? I don't see why intelligence would be the same when you're asleep. People have been known to walk and talk in their sleep, and they certainly don't act as smart as people who are awake. — DanielLC 21:23, 29 December 2010 (UTC)

Actually, people have been known to perform highly complex activities while sleepwalking (although our article, Sleepwalking, says such claims are disputed). --Tango (talk) 21:28, 29 December 2010 (UTC)

What particular measure of intelligence do you propose? The WAIS may be difficult to administer to someone who is unconscious. As I stated, the very concept of quantifying intelligence is problematic even for humans. Its hardly a rigourous, scientific thing. This is even moreso for animals; assigning a quantity, which may not have any real meaning, to a subject which cannot even be tested for that quantity, is doubly meaningless. --Jayron32 21:29, 29 December 2010 (UTC)

And you can't test the intelligence of a sleeping animal anyway. Intelligence is not something floating around in your blood. When they talk of animal intelligence, they either talk in very large generalizations regarding the forebrains of an entire species (which you could do about humans, too, but it doesn't tell you anything surprising, asleep or otherwise) or they talk about things like problem solving, which require being awake to measure. --Mr.98 (talk) 22:29, 29 December 2010 (UTC)

I wouldn't recommend a test designed for humans. How do they compare the intelligences of animals? Can't they also do stuff like use an MRI to see what sections of the brain are being used, an other tests to see what those sections actually do?

Looks like I forgot to sign that. Isn't there supposed to be a bot for that? — DanielLC 00:39, 30 December 2010 (UTC)

"...one cannot take any test while asleep"
Not so: Multiple Sleep Latency Test, Polysomnography. Mitch Ames (talk) 01:15, 30 December 2010 (UTC)

If you included dreaming I'd say just as intelligent as the person was when awake, but with a distorted perception of reality. 82.44.55.25 (talk) 21:26, 29 December 2010 (UTC)

Sleep (see article) is clearly a period when the person does not demonstrate their intelligence. For example, the sleeper is oblivious to unexpected dangers and will not converse. However experiments in sleep deprivation show that sleeping has a rejeuvenating effect on memory whose health is essential to intelligence, see the article Sleep and memory. Higher mental activities such as learning and creativity (see articles) can also occur during sleep. A possible answer to the OP is that the sleeper's mind is liberated from its survival needs to be intelligent, conscious and coherent, but that all the mental resources to be so are present in latent form. The Autonomic nervous system continues in sleep to control essential functions such as heart rate, respiration and digestion but these are classed as evolved rather than intelligent functions. Cuddlyable3 (talk) 21:55, 29 December 2010 (UTC)

They don't show much intelligence. There's still some. — DanielLC 00:39, 30 December 2010 (UTC)

Oxygen difluoride

Is it a colorless gas? --Chemicalinterest (talk) 21:06, 29 December 2010 (UTC)

Apparently. For these sorts of questions about the appearance of chemical compounds, a Google search for something like oxygen difluoride appearance generally gives pretty good results. TenOfAllTrades(talk) 21:57, 29 December 2010 (UTC)

Wormholes

From what I have heard in the past Hawking said that wormholes cannot exist because if matter gets sucked into the blackhole, it gets destroyed. So one cannot "enter" a blackhole and survive it. So what's the latest theory about it?

Also I have read in a newspaper that all blackholes leads to a new universe. Is that true?

Please explain in layman terms without complex equations.

--Tyw7  (☎ Contact me! • Contributions)   Changing the world one edit at a time! 00:04, 30 December 2010 (UTC)

Total non-expert opinion: The only way we have to test such a thing with our current level of technology is through "thought experiments." It may be decades or even centuries before we can actually know the answer to such a question with any degree of certainty. So, Hawking is probably right, but even he doesn't know for sure. Beeblebrox (talk) 00:32, 30 December 2010 (UTC)

The relevant article is Black hole information paradox. AFAIK Hawking capitulated on the point of destruction of information. Vespine (talk) 00:40, 30 December 2010 (UTC)

Yes, and also our Wormhole article says: "There is no observational evidence for wormholes, but on a theoretical level there are valid solutions to the equations of the theory of general relativity which contain wormholes." WikiDao ☯ (talk) 00:43, 30 December 2010 (UTC)

So one cannot use a blackhole (and white hole) as a shortcut because all matter entering a blackhole is destroyed and converted to energy. --Tyw7  (☎ Contact me! • Contributions)   Changing the world one edit at a time! 00:48, 30 December 2010 (UTC)

No, one can not do that because as far as we know they don't exist. There are some thought experiments where they have them, but don't confuse that with actually existing. BTW if you really could convert all matter entering a wormhole to energy that would be tremendously useful, plus you could use them for long distance communication. But in any case the difference between matter and energy is not very clear, so I don't see why a wormhole would allow one and not the other. Ariel. (talk) 01:22, 30 December 2010 (UTC)

How about whether each blackholes lead to a new universe? --Tyw7  (☎ Contact me! • Contributions)   Changing the world one edit at a time! 00:48, 30 December 2010 (UTC)

I haven't heard anything like that. But some people define the inside of a black hole as a different universe since it's isolated from its parent. Ariel. (talk) 01:22, 30 December 2010 (UTC)

Sugar Maple

I recently watched Subway (Homicide: Life on the Street). As Vincent D'Onofrio's character is dying, one of the last things he says is that the leaves of a sugar maple turn upward before a rain to catch the raindrops. Our article doesn't mention this so I'm wondering if anyone knows if it is true or not. Beeblebrox (talk) 00:26, 30 December 2010 (UTC)

I don't know whether or not it is actually true, but a google book search reveals that it is genuine folklore at least. SpinningSpark 01:04, 30 December 2010 (UTC)

I doubt it's true. Why would a maple want to catch water on its leafs? Plus how could it do it before the rain? Ariel. (talk) 01:18, 30 December 2010 (UTC)

(edit conflict) Here's an actual link for that: [13]

Speculation: there is often an updraft before a storm – the leaves of many trees will "turn up" in a very distinctive way preceding rain in that case, perhaps sugar maple leaves doing so are particularly distinctive...? WikiDao ☯ (talk) 01:20, 30 December 2010 (UTC)

In the UK there is a common phenomenon during summer whereby the leaves of trees appear to turn up, but in fact are showing there undersides because they are lifted by a southerly or south-westerly wind which often precedes a rain bearing atmospheric depression. Caesar's Daddy (talk) 08:39, 30 December 2010 (UTC)

An unusual problem with viewing a 3D film.

There is, to my knowledge, a certain percentage of people that cannot see stereographic 3D effects - I am not among them. I am somewhat of a 3D enthusiast, I am a master of stereogram viewing (both parallel and cross-eyed) and enjoy viewing anaglyph images and autostereograms. I have seen many 3D movies in a variety of formats, including IMAX 3D and Fusion Camera system - either of which was apparently used to present the 3D in Tron: Legacy, a movie I saw just 20 minutes ago.

So you can understand why I am utterly confused by the fact that at the moment the movie was supposed to change over to 3D, I saw nothing of the sort - the image was flat. I had gone to see the film with a group of friends, and they all saw the 3D effect fine, and they are not the practical joking type. I switched my glasses with one of them during the credits and she said she saw the 3D clear as day, so it wasn't the glasses. All throughout the film I was stupefied, wondering whether we sat down in the wrong theater. I closed one eye and the other to check if the images for each were different for each eye, but they were identical. I took off the glasses and saw slight blurring like the image was focused "behind" the screen (and in fact I could see a slight 3D effect of the image "behind" the screen when I looked at the edges with the glasses on), but not the characteristic difference of blurring between near and far focused objects.

The biggest mystery was the previews, all of which were in 3D. I saw them in all their glory. The 3D effect in some of them took my breath away. And yet during the movie I saw none of that. I was very disappointed by this development.

I decided half-way through that they put the wrong version on and just enjoyed the movie. But when I told my friends it wasn't 3D they looked at me like I was crazy. I thought about it during the drive home, and I came to the conclusion that what happened to me was impossible, but it happened!

What could have caused me, someone who has never had a problem seeing 3D, to have this happen? This is the most bizarre thing that has ever happened to me, and I want to know what caused it so I can keep my sanity. Thanks in advance. Chris16447 (talk) 07:35, 30 December 2010 (UTC)

The only explanation I can think of is that your experience with autostereograms caused you to mentally cancel out the 3-D effect. As you will know, 3-D vision is processed entirely within the brain as an interpretation of what is "seen" by the eyes, so there must have been some discrepancy between what you expected to see and what was actually received by your eyes. I'm surprised that this lasted throughout the whole film. If it ever happens again, try closing your eyes for a while, then persuade yourself that the picture is just 2-D, then open your eyes and be pleasantly surprised. Dbfirs 10:24, 30 December 2010 (UTC)

Amount of Lanthanum Chloride in a solution.

If a solution is 40% Lanthanum chloride and 60% water, how much pure Lanthanum chloride is there in 5mL of the solution? Abbott75 ღ 12:35, 30 December 2010 (UTC)