Welcome to the science section
of the Wikipedia reference desk.

Select a section:

WP:RD/S

Want a faster answer?

Main page: Help searching Wikipedia

How can I get my question answered?

Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
Post your question to only one section, providing a short header that gives the topic of your question.
Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
Don't post personal contact information – it will be removed. Any answers will be provided here.
Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
Note:
- We don't answer (and may remove) questions that require medical diagnosis or legal advice.
- We don't answer requests for opinions, predictions or debate.
- We don't do your homework for you, though we'll help you past the stuck point.
- We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

September 1

Is infinite zoom originated from Mandelbrot set?

Is infinite zoom originated from Mandelbrot set? Rizosome (talk) 03:44, 1 September 2021 (UTC)[reply]

What is Infinite zoom? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:04, 1 September 2021 (UTC)[reply]

This is example of infinite zoom. Rizosome (talk) 05:42, 1 September 2021 (UTC)[reply]

The Powers of Ten films precede the discovery of the Mandelbrot set. The 1977 version starts with a zoom out from a human scale to one in which clusters of galaxies are mere points of light, and then zooms back in to the original image and continues to the subatomic level. Long zoom sequences had been made before in films, but nothing as long as this. --Lambiam 08:06, 1 September 2021 (UTC)[reply]

No, it is more related to the Droste effect. The Mandelbrot set is a mathematical description which, when visualized, gives a cool fractal geometry. Since this visualization is self-similar, an animation of it will show (approximately) repeating patterns when zoomed enough. Rmvandijk (talk) 09:36, 1 September 2021 (UTC)[reply]

A zoom on the Mandelbrot set can be seen here (Youtube) or you can choose your own area of zoom here. Mike Turnbull (talk) 11:23, 1 September 2021 (UTC)[reply]

It should be noted that while the visualizations of the Mandelbrot set are self-similar, being self-similar is not a defining characteristic of fractals. See This video for a good explanation of fractals and their properties. --Jayron 32 16:00, 1 September 2021 (UTC)[reply]

Are there any good organizations that help specifically Narwhals?

Are there any good organizations that help specifically Narwhals? 2001:569:7D98:E00:98C2:EEE7:2572:77E4 (talk) 04:20, 1 September 2021 (UTC)[reply]

I don't think that Narwhals specifically need support since their habitat is the Arctic and their conservation status is "least concern" (see ref in article you linked to). However, you can find charities that support sea creatures by Googling Narwhal + charity (which gives ORCA and WWF, for example). Mike Turnbull (talk) 11:33, 1 September 2021 (UTC)[reply]

It should be noted that, according to Narwhal, the species was, until recently, categorized as "nearly threatened"; meaning that conservation efforts were needed to raise their numbers. There may be some concern that additional efforts are needed to maintain good, healthy populations given their recent status change. The World Wildlife Fund has information on their narwhal conservation efforts here. Perhaps the OP could look into that organization. --Jayron 32 15:59, 1 September 2021 (UTC)[reply]

Thank you Jayron32. I will look into the organization! 2001:569:7D98:E00:98C2:EEE7:2572:77E4 (talk) 20:08, 1 September 2021 (UTC)[reply]

September 2

Does fluctuations in brightness of bulb visible if it done like this?

AC current means frequency more than 0. So at less frequency of AC (below 50hz), fluctuations in brightness of bulb visible to human eyes? Rizosome (talk) 01:38, 2 September 2021 (UTC)[reply]

As suggested in Utility frequency, if it drops below 60 or 50 it can produce noticeable flickering. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:54, 2 September 2021 (UTC)[reply]

See also Flicker fusion threshold. Whether flicker is perceived at 50 Hz depends strongly on the depth of the modulation. The power delivered is proportional to the square of the current, which for alternating current means that the power frequency is twice that of the frequency of the current. In a formula,

\left(\exp j\omega t\right)^{2}=\exp j(2\omega )t.

This means that the effective (light strength) frequency for incandescent light bulbs is twice the nominal frequency, so 50 Hz AC becomes 2 × 50 Hz = 100 Hz. Also, for such bulbs, the filament cools down only very little when the current passes through zero, so they keep emitting light with only minor changes in intensity and the flicker is not perceptible to the human eye. It will probably remain imperceptible at 35 Hz. With some older types of fluorescent tubes that basically went on and off, the flicker could be annoyingly noticeable also at 60 Hz. Some older CRT displays also had perceptible flicker at these frequencies. --Lambiam 09:58, 2 September 2021 (UTC)[reply]

Edward Sonstadt

Edward Sonstadt was a British chemist. He made magnesium ribbons for photography in 1860s. Does anyone have his photo? Thanks in advance.

Gold anchor chain

Is it possible to make an anchor chain out of solid gold (as described in Alexander Green's novel of the same name), or would it break under the weight of the anchor and/or the stress placed on it by the momentum of the ship? If this is in fact possible, would it be a good way to hide stolen gold (as also related in the same novel)? 2601:646:8A81:6070:5CE9:B4CB:370A:7A2C (talk) 06:43, 2 September 2021 (UTC)[reply]

Mechanical the strength of gold is only about a fifth of a steel, that could be used for an anchor chain. Links of a golden anchor chain therefore would have to be scaled up accordingly (cross-sections, five-fold). This would increase the weight of the chain fifteen times, so it probably wouldn't be manageable for that certain actual use any more. However, it's just lying around on the ship it could still serve as sort of hiding place. --87.147.179.79 (talk) 12:29, 2 September 2021 (UTC)[reply]

How did you calculate the 15 times? scaling the cross section with 5 scales the volume with 5^(3/2), which my calculator makes as ~11.2. A quick calculation shows that, with a yield strength of 80 MPa (N/mm2), to anchor a 10 tonne boat you'd need shackles with a total cross sectional area of 1226mm, or about 13mm radius for 2 circular sections. That is a lot bigger than the steel chains you'd use but a useful ruse in calm weather. I'd hide it at the bitter end of the chain and not (actively) use it. Rmvandijk (talk) 13:45, 2 September 2021 (UTC)[reply]

I did mean with ″cross-section″ the ″cross-sectional area″. And for the material-strength I made an estimated guess (is that a correct English expression?), thus as steel is about five times stronger. Same regarding the densities, thus as gold is about three times denser than steel: 15 results from 3 times 5. --87.147.179.79 (talk) 19:02, 2 September 2021 (UTC)[reply]

This isn't the Language desk ;) but: are you thinking of the English phrase educated guess? —Tamfang (talk) 00:54, 6 September 2021 (UTC)[reply]

When you say "novel of the same name", it might help to have mentioned the name. I guess it's The Golden Chain (a phrase not previously appearing in this section) by Alexander Grin. —Tamfang (talk) 00:53, 6 September 2021 (UTC)[reply]

Ancient horses

Were there any differences in appearance between ancient horses (classical antiquity until Roman times, e.g. those in cavalry) and modern horses due to selective breeding (assuming the same breeds perhaps)? 212.180.235.46 (talk) 18:16, 2 September 2021 (UTC)[reply]

The Nisean horse breed was apparently large and robust. Following the rather patchy links from that article, it seems to be possibly of the archetype "forest horse" which is also called "hypothetical warmblood subspecies" in History of horse domestication theories, and may have been the ancestor of the Latvian horse and the Groningen horse. So that gives you a vague and dubious impression of what some horses from classical antiquity looked like. Horses in the Middle Ages says "During the Decline of the Roman Empire and the Early Middle Ages, much of the quality breeding stock developed during the classical period was lost due to uncontrolled breeding and had to be built up again over the following centuries," confirming at least that there was such a thing as horse breeding in classical antiquity. Card Zero (talk) 19:27, 2 September 2021 (UTC)[reply]

Classical-era horse breeding was certainly a thing. Xenophon had something to say about it in his ~355 BCE textbook On Horsemanship (which in translation is very readable) and there are surely other surviving classical treatises on the subject (about which I'm not an expert). Further, we have quite a few equine carvings and statues from the classical era, which illustrate how horses then looked, and differed from wild breeds. We have been selectively breeding horses for more than 5,000 years. See also List of horse breeds#Archaic types. {The poster formerly known as 87.81.230.195} 2.122.0.2 (talk) 15:52, 3 September 2021 (UTC)[reply]

That last link you gave is about the Middle Ages, when horses were classified by how they looked and what they were for, and so they weren't being selectively bred, at least not deliberately. (Or should that be "not carefully"?) That's why I was unsure to what extent the ancient Greeks (etc.) were selectively breeding them. Card Zero (talk) 20:06, 3 September 2021 (UTC)[reply]

Qualifying for organ/tissue donation

I have been registered as an organ donor on my driver's license, for decades. Now, I am a six year (breast) cancer survivor, plus I'm in my early 60s. Are my organs/tissues still of use, despite my previous cancer? This seems possible. ^[1] But what about a person's age, in regards to various organs and tissues?

Also, I "read something" where the child of an end-of-life, unconscious/comatose parent, said they were dissuaded from providing their parent with opioid medications, because this would prohibit the organs from being transferred to a person who needed them. (Do opioid meds truly ruin the organs?) Haven't found the answers, thus far, in WP articles. Thanks, Tribe of Tiger ^{Let's Purrfect!} 19:49, 2 September 2021 (UTC) [reply]

References

^ "Can I Donate My Organs if I've Had Cancer?". www.cancer.org.

It's good to hear you're doing well. There have been well-reported cases of cancer survivors whose organs were transplanted into someone and the cancer recurred. It's likely that the cancer survivor's immune system was successfully keeping the cancer in check, but there were a few cancer cells lurking around which could cause cancer when transplanted into someone immunosuppressed. I can't find the specific paper I'm thinking of, which is annoying as I think I remember a lot about it-if I recall right it was published by a team at Ninewells Hospital, Dundee and concerned a melanoma survivor who'd died for unrelated reasons. I think it was published around 1999-2001. This is, of course, not medical advice and these judgments are up to clinicians able to make decisions based on a person's specific situation, the level of risk that's acceptable and the risk/benefit tradeoffs. I would keep your donor card, basically. (If I remember rightly, what the doctors did was take the people who'd received this person's organs off the immunosuppressant so that their immune system would learn to recognise the transplanted organ and cancer cells both as non-self.) Blythwood (talk) 23:08, 2 September 2021 (UTC)[reply]

Negative prices for electricity

It seems that when the sun is shining and the wind is blowing, and there are not enough people turning on their AC, sometimes the electricity gets so cheap that you actually need to pay to get rid of it. Why's that? Why not handle that surplus of energy by attaching 2 wires to a big chunk of steel and let it melt? Even if you won't use the stored energy and open a window to release the heat, you'd still make money in a way that the electricity companies must have thought about themselves. So, what's so hard about getting rid of excess electricity? Joepnl (talk) 20:46, 2 September 2021 (UTC)[reply]

It's that electricity companies are in many countries obliged to supply electricity. They aren't allowed to go "eh, not worth it right now, we're making a loss" and just turn your power off. Negative prices are energy company 1 finding they have to keep a power station or a solar panel running when few people want the energy. More explanation here. Blythwood (talk) 22:35, 2 September 2021 (UTC)[reply]

Surely there are bitcoin miners camped around the power plants waiting for such moments ;). 2601:648:8202:350:0:0:0:2B99 (talk) 22:43, 2 September 2021 (UTC)[reply]

@Blythwood That explains why too much electricity is generated once in a while. Not why it's so hard to get rid of it when you produce too much and would actually pay to fix that problem. And yes, certainly a win-win situation for bitcoin miners :) Joepnl (talk) 23:00, 2 September 2021 (UTC)[reply]

Yes, I have to admit I'm not an electrical engineer so I'm not an expert on the physics. Ideally yes, as you say, you'd have something like pumped storage or molten salt storage. Blythwood (talk) 23:14, 2 September 2021 (UTC)[reply]

The situation in Australia is as you describe. I do not know why commercial wind or solar operators don't just switch off their systems when the price goes negative. They are proposing to start charging residential solar systems if they supply 'unwanted' electricity. Many unknowns. Here's an example, where in Vic the price had maxed out, yet Tasmanian operators were being charged for supplying electricity

Greglocock (talk) 00:29, 3 September 2021 (UTC)[reply]

Based on [1] (and a few other less complete sources that I found using the search "electricity negative spot prices"), the answer is that power transmission lines are so designed that excess power in one area might be impossible to transport onto another area (where potential "power sinks" would reside). I am also pretty sure that "bitcoin miners" (as well as more generally high-power consumers) need to run their "plant" more often than "whenever prices are negative" to break even on their capital expenditure; and they potentially have some cost and/or delay associated with switching the plant on or off.

From the generation side (same source), it is not feasible to turn off power plants at a short notice, and furthermore certain power sources (wind and solar?) receive subsidies based on how much they produce, so that they are OK with selling at negative prices as long as it is not too negative. In the source the subsidies are a flat sum per MWh, but a guaranteed price for residential producers would cause the same effect. Tigraan^{Click here for my talk page ("private" contact)} 08:44, 3 September 2021 (UTC)[reply]

The best large-scale method of storing surplus energy is pumped storage, where conventional hydroelectric power plants are used "in reverse". See List of pumped-storage hydroelectric power stations for where this is used on a global basis. The key aspect is the efficiency of the storage/re-use cycle. The OP's suggestion of melting steel would be a case where it was difficult to re-use the stored energy. Mike Turnbull (talk) 11:04, 3 September 2021 (UTC)[reply]

One of the problems with pumped storage hyrdo is that it is land-intensive and requires a particular geography. There's concerns that it won't scale with increasing energy demands on the system; that is the need for more storage will quickly outstrip our ability to build reservoirs to pump water into. Also, you actually need water for that to work, and in many places that have lots of sun and wind where pumped hydro storage is a good idea to stabilize renewable energy, they have major water problems. Look up a recent picture of Lake Mead for example. If you're going to tuck a pumped storage hydro plant somewhere in the Sierra Nevadas or something like that, where is the water going to come from? --Jayron 32 11:09, 3 September 2021 (UTC)[reply]

Electrical demand HAS TO equal electrical output. If there is excess electrical energy in the system, it has to go to another form of energy. If you don't have anywhere else for it to go, it becomes heat... and that heat does stuff like melt wires and other electrical equipment... bad times. You need to have other places for that excess energy to go. Batteries store the extra energy as chemical potential energy. Pumped-storage hydroelectricity stores that energy as gravitational potential energy. But excess electrical energy output HAS TO go somewhere, the first law of thermodynamics is a mean bitch like that. Energy must be conserved. So, if the electrical system doesn't have enough storage for your extra electricity that you want to generate, they need you to shut it down. They encourage that by charging you extra for the extra electricity you are making. Because if you keep making it, they have to find something to do with it, which costs them money. Most electrical systems are working on storage options and expanding capacity, but unless and until they get to the point where they can take your extra electricity, they don't want it. With many utilities, they will discount your electrical bill if you make your own solar, because your demand is still exceeding your production. However when large scale producers (i.e. not just you in your home) produce excess electricity, they aren't producing any demand. It's just a bunch of electricity from solar panels or turbines or something. They either have to shut down or pay the utility for storage. See this video from Physics Girl that explains both the infrastructure challenges and economics of this. --Jayron 32 11:09, 3 September 2021 (UTC)[reply]

One of the other storage methods becoming feasible where there aren't the facilities for pumped storage is battery technology. Remember Elon Musk's 100MWh installation in Australia?. It has been suggested, not entirely in jest, that when we all convert to electric cars, we can use their batteries for storage (keeping running costs down). Mike Turnbull (talk) 11:29, 3 September 2021 (UTC)[reply]

Battery technology presents its own challenges, especially with regards to materials and scalability as well. There is something to be said that batteries in vehicles (which are going to be used to drive anyways) represent a real source of electrical storage available to the system in the future, but large banks of idle batteries, which could represent a part of the storage solution, do not represent enough of a solution. The actual solution will likely involve a diversity of storage option, no one of which represents a significant portion of the total, but all of which are necessary. --Jayron 32 12:47, 3 September 2021 (UTC)[reply]

This problem of surplus energy is ongoing in the Orkney islands, which already generate up to 140% of their energy consumption with wind and tidal power, and could host the infrastructure to generate a lot more. However, they're constrained by the current (pun unavoidable) 40MW maximum capacity of their link with the mainland of Scotland (and Great Britain's National Grid, in turn linked to several other European counties' grids), as adding to this would be much more expensive than installing more wind and tide generators. The way forward may be to use the surplus to manufacture hydrogen from seawater, and export that.

It's explained more eloquently in this recent video on Tom Scott's YouTube channel. {The poster formerly known as 87.81.230.195} 2.122.0.2 (talk) 15:37, 3 September 2021 (UTC)[reply]

An excellent video I also considered linking when I linked Diana's video above. Thanks for that! --Jayron 32 15:42, 3 September 2021 (UTC)[reply]

Hurricane flood water

Where does most of the flooding from a hurricane come from? E.g. New York appears to be under 3 feet of water now, and of course Louisiana had it even worse. Is it ocean water that got swept in by the cyclone, or is it actually ultra powerful rain (i.e. evaporated water that recondensed)? Is it drinkable (like rain water)? Undrinkable because it's full of ocean salt? Or undrinkable pretty much everywhere (even filtered) because of contaminants on the ground getting into it? I'm in California under a drought, but I guess they can't send any of the hurricane water here regardless. Thanks. 2601:648:8202:350:0:0:0:2B99 (talk) 22:42, 2 September 2021 (UTC)[reply]

It comes down as rainwater, buy where it collects it is largely surface runoff and therefore contaminated with any filth you will find on the ground. --Lambiam 01:58, 3 September 2021 (UTC)[reply]

It can also be contaminated by sewage, since the normal sewer system (whether combined or not) will not be working properly. --184.144.99.72 (talk) 06:47, 3 September 2021 (UTC)[reply]

I remember turds on the Embarcadero (San Francisco) after one particularly heavy storm. —Tamfang (talk) 01:07, 6 September 2021 (UTC)[reply]

It depends, though there are typically two different sources of flooding in a hurricane:

Storm surge is water that is "pushed up" onto land from the ocean that is driven by the extreme low pressures and high winds of the hurricane. In coastal areas, such as where the storm makes landfall, much of the flooding is caused by storm surge rather than rain.
Rainfall itself can cause flooding, especially in areas where there is not a means to quickly dissipate the accumulating waters. In places like Philadelphia, for example, the Vine Street Expressway is an impermeable ditch that runs lower than the rest of the city. The massive amount of rain that fell (as quickly as 2-3 inches in one hour, over several hours) all finds the lowest point, which in that part of the city was the expressway, meaning that most of the rainwater ended up turning the expressway into a canal. The water filled the entire depressed roadway (5 meters or so of it) up to street level with water. Yes, there are storm drains, but these can only remove water so fast, they also get clogged with debris, and as a result, there's just no way for the water to drain fast enough. Look at images like [2] show the scope of the problem. Major cities like New York and Philadelphia have all of this sort of "artificial geography" that under these heavy rain conditions will just collect water, like depressed freeways or subway systems. That's why, even in an inland city like Philadelphia (or a well-protected coastal city like New York) you still get massive flooding; even if there was not a storm surge issue, you still get rainwater problems. --Jayron 32 18:10, 3 September 2021 (UTC)[reply]

The NY subway has always had water pumps (and they're still good enough almost 100% the time) but most of the system is 80-117 years old, the street drain system is old and anthropogenic rain rates are starting to obsolete them. The recent tropical depression (remnant?) smashed the Manhattan, Newark etc weather stations' hour records for rain, adjacent hours almost as bad, 2/3rds inches in 5 minutes (!) at a minor weather station and half inch in at most 5-6 minutes in most of the city, that overwhelmed or bypassed the pumps to the point that one stairwell became like the scene in Titanic where the waterfall breaks the doors. Sandy of course was the storm surge variant, where most of the sub-"river"bed tunnels (up to 100-150ft below sea level) became filled with saltwater cause the sea level became higher than the lowest air shaft, station entrance or emergency exit. Sagittarian Milky Way (talk) 20:38, 3 September 2021 (UTC)[reply]

(after edit conflict)

Storm surge, as described by NOAA, "is caused primarily by a storm’s winds pushing water onshore" and is distinct from actual rainfall, which is also distinct from precipitable water, and forecasted precipitable water; and all of these are distinct from runoff, which is often defined as the actual depth of water above ground.

Depending on where you are and what the weather is doing and what is has been doing historically, the volume of water above ground - in other words, "the water that's causing the flood" at a particular spot - can be primarily attributed to any of these causes (or others). One of the jobs of a hydrologist is to subjectively and quantitatively analyze where each component of floodwater comes from, and how to mitigate its hazards.

The New York office of the National Weather Service regularly publishes a Hydrology analysis as part of their area forecast discussion, a text-product that gets updated multiple times per day (and more frequently when weather emergencies call for it).

The US Geological Survey also has responsibility for some aspects of hydrology science. Here's the main website for the New York Water Center. USGS uses different but related methodology, compared to the National Weather Service, so it's interesting to see how two communities of scientists study the same issue in different ways.

Nimur (talk) 18:17, 3 September 2021 (UTC)[reply]

September 3

Plant questions.

What are some examples of underwater plants that can thrive in saltwater, and freshwater?

What are some examples of plants that can thrive in both basic pH soil, and acidic pH soil?

Is there a correlation? 67.165.185.178 (talk) 00:44, 3 September 2021 (UTC).[reply]

For salt and fresh water, see halophyte vs glycophyte. Don't know about pH. 2601:648:8202:350:0:0:0:2B99 (talk) 03:19, 3 September 2021 (UTC)[reply]

For lists of some aquatic plant species that thrive in sea water, brackish water and freshwater, see Category:Seagrass, Category:Brackish water plants and Category:Freshwater plants. --Lambiam 10:17, 3 September 2021 (UTC)[reply]

Soil_pH#Plant_pH_preferences has a table of examples (with tolerance ranges, because plants have varying degrees of fussiness). I'm not sure if this helps with your final question, given that these are land plants. The pH of the underwater soil that aquatic plants grow in ... is an obscure question. Card Zero (talk) 13:09, 3 September 2021 (UTC)[reply]

Extremophile also has some information on life forms that live in very high or very low pH. --Jayron 32 15:40, 3 September 2021 (UTC)[reply]

September 4

Why don't cyanide millipede curl like other millipedes when it got touched?

Why don't cyanide millipede curl like other millipedes when it got touched? Rizosome (talk) 04:31, 4 September 2021 (UTC)[reply]

Who says they don't? This indicates they curl up into a spiral and then exude cyanide. --jpgordon^{𝄢𝄆𝄐𝄇} 05:03, 4 September 2021 (UTC)[reply]

I read This understand it curl like other millipedes, but why it's called cyanide millipede instead of hydrogen cyanide millipede if it exude hydrogen cyanide to fight predators? Rizosome (talk) 06:10, 4 September 2021 (UTC)[reply]

Common names developed informally over time and are used only for convenience. They are not intended to be accurate descriptions, in fact they are often misleading.--Shantavira|^{feed me} 06:39, 4 September 2021 (UTC)[reply]

Also, the term cyanide can be used as a count noun (as in, “A cyanide is a chemical compound that contains the group C≡N”) or as a mass noun (as in “Cyanide is one of the most famous poisons”). When used as a mass noun to refer to a gas, the usual meaning is “hydrogen cyanide”. Compare the use of the term salt: sodium chlorate is a salt, but when a recipe requires “a pinch of salt“, this means sodium chloride and certainly not sodium chlorate. --Lambiam 07:24, 4 September 2021 (UTC)[reply]

Many millipedes exude HCN compounds when threatened. My giant African millipede Nigel would sometimes startle himself by accidentally stepping in our creek and would leave behind a nasty oil slick. He never sprayed me, though :) JoelleJay (talk) 17:14, 4 September 2021 (UTC)[reply]

Dental care

For a correct dental care, I should take before mouthwash or toothpaste? --94.247.8.8 (talk) 09:46, 4 September 2021 (UTC)[reply]

Were you told they contradict? 67.165.185.178 (talk) 11:18, 4 September 2021 (UTC).[reply]

You should ask your dentist that question. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:25, 4 September 2021 (UTC)[reply]

Can the existence of a soul be proved or disproved with science?

As a Christian, I believe that the body has a soul that is sent to heaven or hell after one's death. In short, can the existence of a soul be proved or disproved with science? Félix An (talk) 23:57, 4 September 2021 (UTC)[reply]

No. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:29, 5 September 2021 (UTC)[reply]

You will have to look at your definition of soul which can be a translation of ancient Greek psyche. You may wish to look at the work of Frank J. Tipler. But I think proof is outside science, and the study lies in Christian anthropology and philosophy. Graeme Bartlett (talk) 01:42, 5 September 2021 (UTC)[reply]

Science hasn't proven anything since 1959, when The Logic of Scientific Discovery pointed out that it doesn't really work that way and disproving things is all we can manage. Card Zero (talk) 02:01, 5 September 2021 (UTC)[reply]

If I produced a live Loch Ness Monster, would that not prove that such a thing exists? -- Jack of Oz ^{[pleasantries]} 22:25, 5 September 2021 (UTC)[reply]

Not in the way you might hope. I mean it wouldn't answer the meaningful questions. "Something called XYZ exists" is just semantics, not a scientific theory. Consider the platypus (as I'm sure you often have). What happens is, somebody produces an animal, and nobody denies that they're seeing something and that the thing, whatever it is, exists. But they don't agree about what exactly it is, how it comes to exist and how real it is. To reach agreement they have to test theories - try to disprove them. Even after extensive testing of your creature, to eliminate the possibility that it's a fake or doesn't live in Loch Ness, new theories about what exactly it is can still arise: we only ever have our best stopgap theory, never a proven theory. Card Zero (talk) 12:26, 7 September 2021 (UTC)[reply]

On the other hand, we're constantly being told you can't prove a negative. We can never say the moon is not made of green cheese; the best we can say is we have found no evidence for it so far. After all, who's to say the rocks and dust we've collected from the Moon aren't made of green cheese in some weird alien way our science hasn't cottoned on to yet? So, if we can't prove stuff, and we can't disprove stuff, where does that leave us? -- Jack of Oz ^{[pleasantries]} 22:55, 7 September 2021 (UTC)[reply]

It leaves us with uncontroversial theories that nobody is challenging. We can't imagine an overlooked test that the rock samples would fail if they were green or cheesy, that hasn't already been covered by some less cheese-specific test. This may of course be a failure of the imagination, but collective failure of the imagination keeps us all on the same page. If anybody even had a hunch that such a test existed then they could start making a fuss about it, and bring "the moon is made of green cheese" into the realm of controversy. Card Zero (talk) 07:32, 8 September 2021 (UTC)[reply]

The point Card Zero is trying to make, which is apt here, is that science is about testing falsifiable concepts. Something in science (a law, a model, a theory, an explanation, whatever) is either consistent with observations and data, or it isn't. "Proof" in the colloquial sense as "shown to be incontrovertibly true for all time" is not a thing science does. It tests falsifiable ideas, which is to say ideas which could be shown wrong. If they observations and data show the idea to be unsound, then we discard the idea. If data and observations are consistent with the idea, it is strengthened as an idea we should probably hold to. The concept of a "soul" is not really falsifiable, so it is outside of the realm of science to deal with. How you deal with such unfalsifiable concepts is up to you, but it's not something "science" has a way to deal with. --Jayron 32 16:46, 8 September 2021 (UTC)[reply]

You put that more clearly than I apparently could. I can't resist quibbling with "it is strengthened as an idea we should probably hold to" part, though. Just because an idea has navigated lots of challenges and not been refuted yet doesn't affect the probabilty of it surviving the next challenge. I'm reminded of the gambler's fallacy, and of the way survival of the fittest is often misunderstood to mean "survival of the best" in some sense. It does mean the idea has been shown to have more verisimilitude than its competitors. But we should be careful not to make an idea into a pet, and will it to succeed, and take its side when it faces new threats in the form of criticisms (though it's kind of human nature to do so). Card Zero (talk) 19:55, 8 September 2021 (UTC)[reply]

Weird, the only churches that I know of that still teach about a literal Heaven are Black churches. Most White churches believe Heaven is just where God dwells, if you are "saved," you simply become part of God's memory. So it's not "do you go to Heaven or Hell," but "do you go to Hell, or not go to Hell." 67.165.185.178 (talk) 03:56, 5 September 2021 (UTC).[reply]

Huh? I have never heard of a Christian church, regardless of ethnic composition, that teaches that it is possible to retain consciousness after death, but only by going to Hell. That sounds like an especially grim teaching. Reminds me of an Ian Watson story or something. Where have you come across this? --Trovatore (talk) 16:42, 5 September 2021 (UTC)[reply]

Maybe this Ian Watson? Our consciousness is co-extensive with our memories, and the subjective sense of self exists only by virtue of that memory being walled in, restricted to the experiences of one individual. There is no a priori reason to think that removing these walls and allowing selves to merge is something dire. In any case, resistance is futile. --Lambiam 22:09, 5 September 2021 (UTC)[reply]

No, I think you're utterly wrong about consciousness or self having anything whatsoever to do with memories. Those are completely different things. I can lose my memory but I am still the same person. It's imaginable that someone else could be given my memories, but that would not make that person me. --Trovatore (talk) 16:28, 6 September 2021 (UTC)[reply]

Imagine that technicologically extremely advanced aliens abduct two humans from different parts of the world, say Abdul and Bobby, and as one of their evil experiments effectuate a swap of their complete memories (and nothing else). The human who wakes up in the body of Abdul will say that subjectively they are Bobby, but inhabiting the wrong body, one that is unfamiliar to them when they look in the mirror. --Lambiam 19:37, 7 September 2021 (UTC)[reply]

Yes, observed from the outside, that's what he'll say. But that's because his word for self is now "Bobby". His self has not actually changed. --Trovatore (talk) 19:39, 7 September 2021 (UTC)[reply]

More likely this Ian Watson. {The poster formerly known as 87.81.230.195} 90.209.121.112 (talk) 04:15, 6 September 2021 (UTC)[reply]

Because there's no verse in the Bible that literally says we go to Heaven if we're saved. (But it does talk about Hell.). I guess the Catholic church believes in a literal Heaven, if they believe in purgatory. Also, Black churches are traditionally against the death penalty, whereas White churches (non-Catholic) love the death penalty. So yes, there are some literal differences. 67.165.185.178 (talk) 03:30, 6 September 2021 (UTC).[reply]

I'm not sure how you missed what Jesus said to the repentant thief on the cross (Luke 23:43). Also he talks about "eternal life" several times (see the end of the parable of the sheep and the goats, or the Samaritan woman at the well. He tells the disciples that he goes to prepare a place for them. As far as I'm aware he doesn't use the exact words "heaven" or "saved", but it clearly sounds like personality continuing. --Trovatore (talk) 16:38, 6 September 2021 (UTC)[reply]

There is also Matt 22:30: For in the resurrection they neither marry, nor are given in marriage, but are as angels in heaven. Iapetus (talk) 10:19, 7 September 2021 (UTC)[reply]

What church? Northern Conservative Baptist Great Lakes Region Council of 1879, or Northern Conservative Baptist Great Lakes Region Council of 1912? Tigraan^{Click here for my talk page ("private" contact)} 10:37, 6 September 2021 (UTC)[reply]

If your concept of soul is that of an incorporeal entity, that is, having no material form and not being subject to the laws of physics, it follows that no scientific experiment can contribute to any judgement about the existence or properties of souls. If, however, you believe that souls are material and possess mass, you can attempt to measure it. --Lambiam 06:50, 5 September 2021 (UTC)[reply]

September 5

How much of Speed of light can be decreased until Universe go unstable?

I feel stability of universe also depends on speed of light. So how much of Speed of light can be decreased until Universe go unstable? Rizosome (talk) 02:56, 5 September 2021 (UTC)[reply]

Where did you get this idea from? Also note that the speed of light varies depending on what it's traveling through. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:23, 5 September 2021 (UTC)[reply]

The metre is defined in the International System of Units (SI) as the distance travelled by light in vacuum in 1/299792458th of a second. It follows that the speed of light is exactly 299792458 metres per second. If it goes down, this means that reciprocals have become unstable. --Lambiam 06:24, 5 September 2021 (UTC)[reply]

That's not a fact about the speed of light; it's a fact about how the meter is defined in SI. I think we have an article called variable speed of light; I haven't looked at it recently and don't know what it currently discusses, but you can't answer the question "what if the speed of light were lower" by talking about a particular system of units. (It would certainly be fair to ask the questioner what is meant.) --Trovatore (talk) 16:19, 5 September 2021 (UTC)[reply]

Let's not some of us lose sight of the fact that the value c, colloquially referred to as "the speed of light," is a fundamental physical constant (we think) which light or other massless entities in a vacuuum necessarily must travel at, but that's an imposition on light by the universe, not something imposed on the universe by light. That light or other massless things travel at different velocities when not in a vacuum has no relevance to questions like Rhizome's.

As to that question, our article Fine-tuned universe may be of interest, as might Fine-tuning. {The poster formerly known as 87.81.230.195} 2.122.0.2 (talk) 19:36, 5 September 2021 (UTC)[reply]

Please read the section Variable speed of light § Dimensionless and dimensionful quantities, and note this quote:

At first we might be tempted to think that a world in which the speed of light was slower would be a different world. But this would be a mistake. If c, h, and e were all changed so that the values they have in metric (or any other) units were different when we looked them up in our tables of physical constants, but the value of α remained the same, this new world would be observationally indistinguishable from our world. The only thing that counts in the definition of worlds are the values of the dimensionless constants of Nature.

--Lambiam 21:56, 5 September 2021 (UTC)[reply]

But what if c alone were different, such that the value of α was also different? (I am asking on behalf of Rhizome, of course.) {The poster formerly known as 87.81.230.195} 90.209.121.112 (talk) 04:25, 6 September 2021 (UTC)[reply]

There is a shallow discussion at Fine-structure constant § Anthropic explanation, although I wonder if the presentation correctly reflects the cited source. --Lambiam 07:26, 6 September 2021 (UTC)[reply]

Production of Chloroquine and Hydroxychloroquine

How are chloroquine and hydroxychloroquine produced by the pharmaceutical companies? Are they made semi-synthetically from the bark of the cinchona tree? Our articles on those medicines don't seem to say how they are manufactured or produced? (Maybe our articles should be expanded to include that information, as described in reliable sources, but this is the Reference Desk, not a content form.)

I am not asking whether they have value in treating or preventing covid. We know that they do not. I am only asking how these medicines are produced. Robert McClenon (talk) 21:07, 5 September 2021 (UTC)[reply]

In organic chemistry, you learn reactions are made through a series of steps involving SN2, SN1, E2, and E1. The trick is to know what the starting materials are. (I.e., fusing 2 benzene rings into 1.). Then, there's selecticity, i.e., adding a substituent in the ortho-, meta-, or para- position. 67.165.185.178 (talk) 03:32, 6 September 2021 (UTC).[reply]

The original source from cinchona was severely limited in World War II, when these compounds were first in demand as anti-malarials. Hence purely synthetic routes were developed. Articles from the time include this report from 1949 and this thesis. I'm not sure how large-scale manufacture takes place today and it is a shortcoming of the Wikipedia articles that this aspect is not covered. Mike Turnbull (talk) 11:13, 6 September 2021 (UTC)[reply]

I've now updated the chloroquine and hydroxychloroquine articles to add the chemistry in their history sections. Mike Turnbull (talk) 13:58, 7 September 2021 (UTC)[reply]

Chloroquine is a de novo synthesis; cinchona bark was never in the mix. You can reliably source possible syntheses but I don't think you could reliably source manufacturing process(es). UNIDO for example had to interpolate in 1985 ("step-by-step technical and economic details were not always available...") [3], and the ACS article above illustrates how a bench synthesis may have to be "translated" to manufacturing; that's the sort of detail I'd be surprised to see published. "Synthesis of Essential Drugs" [4] has more detail on synthesis but probably fails WP:NOTTEXTBOOK. Yappy2bhere (talk) 21:45, 8 September 2021 (UTC)[reply]

Production of Ivermectin

How is ivermectin produced by the pharmaceutical companies? Is it produced by extraction and processing from the product of certain bacteria? (If so, are the bacteria soil scavengers that are producing the vermicides in order to compete with worms in scavenging the soil?) Our article sort of implies that, but only sort of implies that. (Maybe it should be expanded, but this is the Reference Desk.)

I am not asking whether ivermectin has value in treating or preventing covid. We that it does not. I am interested in the origin of the nonsense belief. Robert McClenon (talk) 21:07, 5 September 2021 (UTC)[reply]

Regardless of how ivermectin is produced – which IMO is irrelevant to the origin of (incorrect) stories about the presumed efficacy of ivermectin in treating COVID-19 – there is a rational basis for its consideration. In a controlled in vitro study, a 5000-fold reduction in viral RNA after exposure to ivermectin compared with control was found in cells infected with the SARS-CoV-2 virus.^[5] Unfortunately, this did not translate to good results in clinical trials.^[6][7] --Lambiam 21:46, 5 September 2021 (UTC)[reply]

Yes, according to the 1983 source and 2017 "Ivermectin – Old Drug, New Tricks?": it's a purified product treated by reaction with hydrogen (hydrogenation). I can't find an explicit statement of why the bacteria make it, but it seems likely. Blythwood (talk) 00:25, 6 September 2021 (UTC)[reply]

Infinite-fold virus reduction is easy, just eat ivermectin until dead and if that fails dissolve body in acid until nothing left. Sagittarian Milky Way (talk) 00:47, 6 September 2021 (UTC)[reply]

That approach works in a sense, but it's close kin to throwing the baby out with the bathwater. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:41, 6 September 2021 (UTC)[reply]

[8] [9] also seem to confirm. Nil Einne (talk) 09:21, 6 September 2021 (UTC)[reply]

To answer your question, Robert McClenon, Ivermectin#Chemistry describes the production process. The bacterium is Streptomyces avermitilis and it produces avermectins, as described in this book chapter. As with other pharmaceutical products, the strain of S. avermitilis used in production now will have been considerably optimised for yield. The avermectins were mainly developed as commercial insecticides. Ivermectin is a synthetic derivative in which one of the double bonds is reduced by hydrogenation and this is the compound mixture marketed as an antiparasitic agent for human use. Your suggestion that the bacterium gains a competitive advantage by poisoning other soil organisms is plausible but I don't think that this has been established. Mike Turnbull (talk) 10:44, 6 September 2021 (UTC)[reply]

September 6

Covid PCR Test

Once you've taken a sample from your tonsils and nostril for a PCR test, is there a limit on the amount of time available to actually test the sample before the test will no longer give valid results? I submitted a test in the post and just wondered what happens if there are delays along the way. Thanks. 88.111.85.155 (talk) 12:37, 6 September 2021 (UTC)[reply]

Extended storage of SARS-CoV-2 nasopharyngeal swabs does not negatively impact results of molecular-based testing across three clinical platforms says: "This study demonstrates that nasopharyngeal swab specimens can be stored under refrigeration or even ambient conditions for 21 days without clinically impacting the results of the real-time reverse transcriptase-PCR testing". Alansplodge (talk) 12:54, 6 September 2021 (UTC)[reply]

BTW, "severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)" is the name of the virus that causes COVID-19 019)-and-the-virus-that-causes-it Naming the coronavirus disease (COVID-19) and the virus that causes it (WHO) Alansplodge (talk) 12:57, 6 September 2021 (UTC)[reply]

Why is there no way to INCREASE energy harvest in the gut?

There are many ways to reduce energy harvest from food. There's gastric bypass surgery; there are enzyme inhibitors like orlistat and acarbose, which reduce absorption of calories from fat and starch; there are even drugs like dapagliflozin, which increase excretion of carbohydrate calories in the urine. There's even a stomach pumping machine that literally sucks food out of your stomach just after you've eaten it. There are also nutrients like fiber and calcium, which can bind to fat in the intestine. Why is there nothing that does the opposite? Of course, I'm sure part of the answer is that so many people need to lose weight for health reasons, but what about people with digestive disorders, for example? These people are mainly just told to avoid certain foods, right? Why isn't there a pill you can take that helps you absorb more fats or carbohydrates? What would be some of the possibilities here (besides, say, expensive digestive enzymes)? Of course, I'm sure there's more interest in reducing energy harvest to reduce obesity, but what could you do (in theory) to help the gut absorb more calories? I've read that even in healthy people, fecal energy content varies significantly (typically between 2-10%), so I think there would be some room for improvement even in healthy individuals (e.g., those wanting to gain weight). Clearly, putting any meaningful number of calories in a tiny pill is impossible, but why can't we make weight-gain pills that help the body absorb more calories from food?173.185.94.69 (talk) 15:46, 6 September 2021 (UTC)[reply]

There's taking antibiotics to kill off gut bacteria and reduce competition, but that's not encouraged. Apparently there's some evidence that antibiotics can cause weight gain, but I'm sure it's debatable how big the impact is. Blythwood (talk) 16:16, 6 September 2021 (UTC)[reply]

In several million years, evolution has fine-tuned the hominid digestive system for maximal energy harvesting. It is a very complex system, and one should not expect that a simple intervention can substantially increase the yield. --Lambiam 19:52, 6 September 2021 (UTC)[reply]

There is such thing as digestive enzyme supplementation. Ruslik_Zero 20:30, 6 September 2021 (UTC)[reply]

Okay, thank you!173.185.94.69 (talk) 21:31, 6 September 2021 (UTC)[reply]

September 7

How can exercise burn stress?

From here, it says: When you exercise, you'll burn off some of your stress.

I know exercise burn calories but how it can burn stress too? Rizosome (talk) 01:41, 7 September 2021 (UTC)[reply]

Start with Exercise, note where it mentions "stress", and continue from there. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:36, 7 September 2021 (UTC)[reply]

STRESS RELIEF - The Role of Exercise in Stress Management describes the hormonal changes involved. The use of the term "burn" seems to be just journalese rather than an accurate description of the process. Alansplodge (talk) 21:06, 7 September 2021 (UTC)[reply]

Special relativity question

Suppose you have a train and its rest length is known. It runs on a track. On one side of the track and there are two light sources shining across the track, perpendicular to it. They are a known distance apart. On the other side of the track, the beams are reflected by mirrors into detectors that are at the position of a clock. The detectors record the time from the clock when they are receiving the light and when they are not. The apparatus is symmetrical with respect to the clock.

The train comes along the track at relativistic speed and the apparatus records the time each light beam is cut off and the time it resumes.

From the time that each beam is cut off and the known distance between the light beams, you can calculate the speed of the train. From that and the length of time that the light is cut off from either beam, you can calculate the length of the train.

Question: This calculated length of the train will show Lorentz contraction, right? Bubba73 ^{You talkin' to me?} 02:52, 7 September 2021 (UTC)[reply]

Is this the same as the ladder paradox? Robert McClenon (talk) 05:41, 7 September 2021 (UTC)[reply]

I don't think it is. The ladder paradox says "This apparent paradox results from the mistaken assumption of absolute simultaneity. " I don't see any use of absolute simultaneity. Bubba73 ^{You talkin' to me?} 06:22, 7 September 2021 (UTC)[reply]

Yes, the Lorentz contraction is a real physical, and measurable, phenomenon, not just a mathematical trick. If you were to measure the length of an object moving at close to the speed of light, it will be smaller in the direction of travel than if you measured it while stationary. This video does a good job of explaining it. --Jayron 32 16:18, 7 September 2021 (UTC)[reply]

Also relevant, this most recent video from Minute Physics has a different experiment to measure length contraction. --Jayron 32 16:20, 7 September 2021 (UTC)[reply]

Yes, that method will show Lorentz contraction of the train's length. --Amble (talk) 20:05, 7 September 2021 (UTC)[reply]

Resolved

That is what I thought, thank you. Bubba73 ^{You talkin' to me?} 21:30, 7 September 2021 (UTC)[reply]

Smartphone's screen smudges

Even though internet states that smartphone screens have an oleophobic coating, the finger smudges on the screen are still there (in my case it's Motorola E7i, but I guess any other smartphone has the same). Is it because the oleophobic coating is too thin to prevent smudges or some other reason? More generally, is it possible to produce a smudge-resistant touch screen? 212.180.235.46 (talk) 19:46, 7 September 2021 (UTC)[reply]

A thicker coating layer will not reduce the amount of sebum transferred to the screen. Such transfer takes place at the outer surface of that layer. No coating can guarantee a full 100% protection against smudge attacks, but matte screen protectors make such attacks less easy. I did not readily see information about the affinity to oil or lack thereof of the Motorola E7i screen, but ads offering oleophobic screen protectors for this model abound. --Lambiam 07:10, 8 September 2021 (UTC)[reply]

Removing ticks?

Just for future reference because i forgot. Are you supposed to twist the tick clockwise or anti clockwise to get it out? 146.200.107.70 (talk) 23:10, 7 September 2021 (UTC)[reply]

Neither. Here's how.[10] ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:54, 8 September 2021 (UTC)[reply]

September 8

Is there a world map that colors pixels by which staple crop has the most human-edible tons/acre potential there?

Weight the way it's usually measured, I think it's dry weight. Or calories per acre, which might penalize maize for its low fat and indigestible but edible shell. Sagittarian Milky Way (talk) 06:35, 8 September 2021 (UTC)[reply]

This looks like it might meet your needs. --Jayron 32 11:55, 8 September 2021 (UTC)[reply]

September 9

Covid question

We know that if a vaccinated person catches Covid, the risk of long Covid or complications is much lower compared to if an unvaccinated person catches Covid.

But is catching Covid from a vaccinated person less dangerous than catching Covid from an unvaccinated person?

Logic is the virus would be weakened by the vaccinated person's immune system.

--219.75.107.21 (talk) 09:36, 9 September 2021 (UTC)[reply]

[1] "Can I Donate My Organs if I've Had Cancer?". www.cancer.org.

[1]