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May 19

Does Wikipedia contain a contradiction about whether, the speed of light is only constant in inertial frames of reference?

On the one hand, our article special relativity states:

In the lead: "The speed of light in vacuum is the same for all observers, regardless of the motion of light source or observer".
In the chapter background: "Two observers in relative motion receive information about two events via light signals traveling at constant speed, independent of either observer's speed".
In the chapter History: "James Clerk Maxwell presented a theory of electromagnetism...The theory specifically predicted a constant speed of light in vacuum, no matter the motion (velocity, acceleration, etc.) of the light emitter or receiver."
In the chapter Reference frames and relative motion: "the speed of light is constant in relativity irrespective of the reference frame".

.

So it seems that the speed of light is constant, also in non-inertial frames of reference.

.

On the other hand, that article also states:

In that chapter: "light in vacuum propagates with the speed c (a fixed constant, independent of direction) in at least one system of inertial coordinates".
In the chapter Basis: The two postulates both concern observers moving at a constant speed relative to each other.
In the chapter Lack of an absolute reference frame: "the speed of light in vacuum is always measured to be c, even when measured by multiple systems that are moving at different (but constant) velocities".
in our article Postulates of special relativity, in the chapter Postulates of special relativity: "As measured in any inertial frame of reference, light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body. Or: the speed of light in free space has the same value c in all inertial frames of reference".
In our article speed of light, in the lead: "Albert Einstein postulated that the speed of light c with respect to any inertial frame of reference is a constant...Such particles and waves travel at c regardless of the motion of the source or the inertial reference frame of the observer".
In that article, in the chapter Fundamental role in physics: "The speed at which light waves propagate in vacuum is independent both of the motion of the wave source and of the inertial frame of reference of the observer...In non-inertial frames of reference (gravitationally curved spacetime or accelerated reference frames), the local speed of light is constant and equal to c, but the speed of light can differ from c when measured from a remote frame of reference".

.

So it seems that the speed of light is only constant in inertial frames of reference.

.

I wonder if the second set of quotes contradicts the first one. HOTmag (talk) 19:04, 19 May 2025 (UTC)[reply]

The implicit assumption in the first set is that the observer shares the frame of reference with the measuring instrument. ‑‑Lambiam 12:08, 20 May 2025 (UTC)[reply]

Of course, but what about two measuring instruments that accelerate relative to each other? Will they measure the same speed of light, according to each set of quotes mentioned in my original post? HOTmag (talk) 00:04, 23 May 2025 (UTC)[reply]

In an inertial frame of reference you can make a local clock by observing a light package bouncing between two parallel motionless mirrors, which can serve as the basis for setting up a coordinate system. The problem is really in how to define a non-local coordinate system from a non-inertial frame of reference. You can write in your lab notes, "Event E was observed at position (

x 1

,

y 1

,

z 1

) at time

t 1

." How did you measure the values of these non-local coordinates? Will they still be in any sense meaningful at time

t 2

? Is the space point (

x 1

,

y 1

,

z 1

) still "where it was" at time

t 1

? ‑‑Lambiam 16:31, 23 May 2025 (UTC)[reply]

I'm referring now to your last three questions: Why can they only be asked when the frame of reference is (non-locally) accelerating, and not when the frame of reference is (non-locally) moving without acceleration? HOTmag (talk) 10:28, 26 May 2025 (UTC)[reply]

@Lambiam: Before it's archived... HOTmag (talk) 06:29, 1 June 2025 (UTC)[reply]

At least according to the theory of special relativity, clocks at different locations in the same inertial frame run at the same rate. This allows the observer to set up a consistent time coordinate. And if A, B and C are at rest with respect to an inertial frame, with B halfway between A and C, it remains halfway. More generally, if their locations are collinear, their relative positions on the line remain unchanged. This suffices to set up a spatial coordinate system. ‑‑Lambiam 07:11, 1 June 2025 (UTC)[reply]

Do your last two responses only show, that measuring the speed of light in a non-inertial frame of reference - is not "meaningful" only (as implied by your middle question in your previous response before your last one), or you also think that - measuring the speed of light (in vacuum) in different non-inertial frames of reference - really result in different values? HOTmag (talk) 09:53, 1 June 2025 (UTC)[reply]

May 20

Is there such a thing as a "heavy gunner" in real life?

You see this in video games a lot. A soldier who is dressed head to toe in a thick kevlar suit/helmet and ballistic plates shooting an LMG or a gattling gun. Often sent out in front of everyone else to cause as much damage to the enemy as possible while standing there and enduring their return gunfire. Does this exist in real life? 146.200.107.90 (talk) 01:58, 20 May 2025 (UTC)[reply]

Only the ones who ride rhinoceri. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:42, 20 May 2025 (UTC)[reply]

Even if the bullets don't penetrate the armor, their momentum is transferred to the lone vanguard soldier (see Physics of firearms § Transfer of energy). The momentum of a bullet fired by an AK-47 is about 6 kg⋅m⋅s⁻¹. (See the info box, Ballistic performance, of 7.62×39mm; this supposes that the bullets don't bounce back, otherwise the imparted momentum is higher.) At 10 rounds per second, the effect of one rifle on automatic continually hitting its target is an effective force of 6 kg⋅m⋅s⁻¹ × 10 s⁻¹ = 60 kg⋅m⋅s⁻², about 6 g. For a lighter machine gun like the Colt IAR6940 I still get some 4.5 g. The warrior will have a hard time advancing. ‑‑Lambiam 11:44, 20 May 2025 (UTC)[reply]

Wouldn't the g-force experienced depend on the weight of the soldier? Alien878 (talk) 08:12, 21 May 2025 (UTC)[reply]

According to Newton's laws the shootee would be pushed back less hard than the sum of the shooters' recoil as they are not getting the full force of the gases leaving the gun. Sagittarian Milky Way (talk) 16:19, 29 May 2025 (UTC)[reply]

I think the step from 60 kg⋅m⋅s⁻² to 6 g is incorrect. G-force is a type of acceleration(specifically specific force), but 60 kg⋅m⋅s⁻² is a force. to turn it into an acceleration you have to divide by the weight the force is acting on, the soldier. this gets 60 kg⋅m⋅s⁻² ÷ 65 kg = 0.9 m⋅s⁻², which gives about 0.09 g. Math Bard (talk) 00:53, 31 May 2025 (UTC)[reply]

In real life this would be a suicidal tactic, so not one that would be routinely planned for by officers, or willingly performed by most soldiers. A few unusually brave individuals may have done similar things in unusual and desperate situations, for which they might well have been awarded a (probably posthumous) decoration. {The poster formerly known as as 87.812.230.195} 94.1.170.37 (talk) 13:53, 20 May 2025 (UTC)[reply]

An unfortunate 'lol' at your 'probably posthumously' there. —Fortuna, imperatrix 14:25, 20 May 2025 (UTC)[reply]

It depends what he had for breakfast. —Fortuna, imperatrix 14:26, 20 May 2025 (UTC)[reply]

I'm surprised nobody mentioned the North Hollywood shootout. Abductive (reasoning) 14:55, 20 May 2025 (UTC)[reply]

One Mr Edward Kelly was an early pioneer of armour vs firearms tactics, although he didn't use or face automatic weapons or machine guns. {The poster formerly known as 87.81.230.195} 94.1.170.37 (talk) 15:41, 20 May 2025 (UTC)[reply]

Curiously, Heavy gun is a redirect to Heavy machine gun, but most occurrences of "heavy gun" appear to refer to crew-served artillery. -- Verbarson ^talk_edits 16:42, 20 May 2025 (UTC)[reply]

An example from the First World War was the Italian Compagnie della morte of late 1915, who were tasked with cutting enemy barbed wire with pliers and wore medieval-style armour.

See this image. Not terribly successful, one Italian officer wrote; "Before going out to attack, they send men with pliers to remove the wires from the enemy fences. Ordinarily, neither pliers nor men return". Alansplodge (talk) 17:34, 20 May 2025 (UTC)[reply]

Looking at the history, that redirect is positively antediluvian. If you're confident there's a better target (er, pun unintended), I'd say go for it -- Avocado (talk) 16:55, 23 May 2025 (UTC) [reply]

I've pointed it to Large-calibre artillery. I have insufficient knowledge to be sure it's the best, but it is definitely better than before. -- Verbarson ^talk_edits 20:43, 23 May 2025 (UTC)[reply]

The short answer, as people have indicated above is no. However, the video-game/media trope has connections with real-life tactics such as Shock troops and Infantry weapons officer. The problem is the trade-off between power and speed. Eluchil404 (talk) 21:36, 20 May 2025 (UTC)[reply]

Contaminated oil

If oil which has been contaminated with seawater is used to fuel an oil-burning steam locomotive (assuming that the temperature is above freezing, so that ice crystal formation is not an issue), is there likely to be an immediate (= within no more than a few hours) failure of the burners in the firebox? Or would the engine be OK for a few days while the maintenance department (or the logistics department, or the fueling department if there is one) gets the problem sorted out? 2601:646:8082:BA0:2C:610F:A84:CB25 (talk) 22:32, 20 May 2025 (UTC)[reply]

The burners in steam locomotive fireboxes were made of iron or steel. The salt in seawater causes them to corrode through a process called oxidation. But this is not the end of the world. If caught early, a technician in the maintenance department should be able to resolve the problem without causing significant long-term damage. Stanleykswong (talk) 06:49, 21 May 2025 (UTC)[reply]

The oxidation process is also known as rusting. ‑‑Lambiam 07:43, 21 May 2025 (UTC)[reply]

Right, I'm aware of corrosion -- what I wanted to know, though, is whether this could cause more immediate problems, e.g. through phase separation causing blockages in the burners and/or fuel lines (analogously to what would happen to a diesel in this scenario)? 2601:646:8082:BA0:95F1:4DFA:95FD:527C (talk) 11:15, 21 May 2025 (UTC)[reply]

Even under normal operation, burner and fuel line blockage is inevitable. There is no doubt that the salt in seawater increases the risk. Stanleykswong (talk) 11:23, 21 May 2025 (UTC)[reply]

Per GWR oil burning steam locomotives, the oil was heated by steam to make it flow, then atomised by steam in the burner to allow rapid combustion. The atomisers had to be removed and cleaned daily. With that level of interaction with steam, and daily maintenance, I doubt that salt water contamination would cause noticeable blockages or further degradation. -- Verbarson ^talk_edits 17:31, 21 May 2025 (UTC)[reply]

So here's what I really wanted to know: in "Thomas to the Rescue" (where all the diesels break down due to seawater contamination of their fuel and Thomas has to bring them fresh fuel from the depot), had Victor and Timothy (the only two oil-burning steamies on Sodor) been on the NWR at the time (they weren't introduced until much later), would they have broken down as well? (Yes, I'm aware that diesels and oil burner (engine)s use fuel with different volatility parameters, but let's ignore that point in this case!) 2601:646:8082:BA0:95F1:4DFA:95FD:527C (talk) 22:12, 21 May 2025 (UTC)[reply]

Steam is less corrosive than salt water. Salt water contains large amounts of chlorides, which are more corrosive to metals due to electrochemical reactions, especially at high temperatures and pressures.

There is no mention in the GWR archives of what atomizer design they used. Of course, for a large engine, using steam sounds like it would make more sense than using air. Also, they did not mention whether the water was pre-treated before use. There is no mention in the GWR archives of what atomizer design they used. Of course, for a large engine, using steam sounds like it would make more sense than using air.

Also, they did not mention whether the water was pre-treated before use. In the electronics industry, deionized water is used to clean printed circuit boards, and it is possible that they used a similar process (maybe a more primitive approach) to remove mineral ions from the water. Or, did they use steam injection or other method to physically remove dissolved oxygen from the water before using it? Stanleykswong (talk) 06:52, 22 May 2025 (UTC)[reply]

OK, never mind the corrosion (it takes weeks for corrosion to start causing trouble) -- what about more immediate failure modes, like an atomizer blockage or a chemistry-related combustion upset of some sort? 2601:646:8082:BA0:95F1:4DFA:95FD:527C (talk) 21:30, 22 May 2025 (UTC)[reply]

This depends on the design of the atomizer. If it is a pressure atomizer, the design is relatively simple. It is actually an oil nozzle, very similar to a sprayer for gardening. If corrosion causes the atomizer to become clogged, simply removing and cleaning the nozzle may resolve the problem. Stanleykswong (talk) 21:55, 22 May 2025 (UTC)[reply]

As stated in the GWR article (and cited to Griffiths 1987, available here, pp.123-124), the GWR ended up with Laidlaw-Drew atomisers, possibly like this.

The same book, p.69, confirms that the GWR had long used water treatment for boiler water, and though was directed to extending boiler life, it would probably have benefitted the atomisers by reducing particulates and dissolved minerals.

Here is a detailed diagram. -- Verbarson ^talk_edits 22:03, 22 May 2025 (UTC)[reply]

Right, but in this case we're talking about water dissolved in the fuel oil as received by the railroad, not water in the form of steam injected into the nozzles to help atomize the oil (which is normal, and which uses purified water from the boiler, as you correctly pointed out). In other words, a scenario similar to that in "Thomas to the Rescue"! 2601:646:8082:BA0:95F1:4DFA:95FD:527C (talk) 01:48, 23 May 2025 (UTC)[reply]

You are asking what would happen in an already fictional situation if the writer had written it differently. The fact is, that anything that would suit the story could happen, up to and including Thomas turning green, the er... physically-enhanced Controller resigning, and pigs flying. If you want to ask a science question, you should specify the grade of oil, the concentration of seawater, and the design of the atomiser and associated pipework. Anyway, I was taught^[1] that oil and water don't mix. Wouldn't the seawater separate out and float on top? -- Verbarson ^talk_edits 17:16, 23 May 2025 (UTC)[reply]

To be fair, the author Wilbert Awdry was knowlegeable (for an amateur) about railways and, outside of the fantastic elements of sapient locomotives and rolling stock, attempted to be as realistic as possible in his plots, many of which were based on or inspired by actual incidents on real-life UK railways.

That said, the OP's deliberate ignoring of the fact that diesel fuel and locomotive fuel oil are two completely different things combusted in completely different equipment, and would not have suffered from the same contamination (unless by two acts of sabotage), in my view rather negates any point of discussing the minutiae of oil-burning locomotives. And as others have explained, seawater-contaminated fuel oil might have caused minor corrosion of parts, but would not have caused a quick breakdown, as seawater in diesel fuel would.

[Edited to add] Note that due to the constant physical agitation endured by a running locomotive, the seawater and fuel oil would, I suggest, probably remain in an emulsified mix rather than settling out. {The poster formerly known as 87.81.230.195} 90.193.154.147 (talk) 22:03, 23 May 2025 (UTC)[reply]

References

^ at my mother's knee

Thanks for the constructive and on-point answer (for once -- Verbarson's latest comment was completely unhelpful, and those of the others were well-meaning but misunderstood the question) -- so, the answer to my question would be "probably not", is that correct? (BTW, the reason why I chose to knowingly ignore the difference in fuel grade is because of the detailed context -- as I think I already have said in an earlier comment, I'm doing some preliminary work on a Thomas & Friends-themed add-on for Train Sim Classic and/or Train Sim World, and this question has to do with one of the scenarios I'm planning, which will be based on "Thomas to the Rescue" -- and in Train Sim Classic at least, oil-burning steamies use the same fueling facilities as diesels (I checked!) And I'm actually kind of glad that the answer to my question is no -- this scenario would already be a marathon of a mission, with the player (driving Thomas) having to haul a train 2-3 times heavier than the normal load for his type all the way up and down the main line (and down and up a few of the branches as well), so I guess the player could do without having to make an extra trip to the china clay quarry to drop off fuel for Timothy!) 2601:646:8082:BA0:95F1:4DFA:95FD:527C (talk) 06:22, 24 May 2025 (UTC)[reply]

Mostly it would, but a small amount (maybe not even all that small, it could range as high as a few parts per thousand) would remain in the oil as an emulsion (had the separation been complete, there would have been no need for desalting/dewatering the oil at refineries, but the fact is, all of them have desalters installed upstream of the atmospheric distillation unit) -- and also, depending on the grade of oil, the water could actually sink to the bottom upon separation (which could lead to it physically displacing the oil from the fuel line, causing immediate burner flameout regardless of the design of the burner), could it not? Also, this is a science question -- I am asking what would happen in a real-life scenario similar to the fictional one which the Reverend had come up with (don't forget, many of his Thomas stories were actually based on real-life incidents he had personally seen or heard about, including one in which he had personally given his train the highball too early by mistake and stranded his passengers)! As for your question re. fuel specs, just for the sake of the argument, let's go with, say, #4 fuel oil and a seawater concentration of, say, 2000 ppm (which, had it been in diesel fuel instead, would be plenty high enough to cause immediate failure of any diesel engine unfortunate enough to use that batch of fuel, or at least that's what my sources tell me!) 2601:646:8082:BA0:95F1:4DFA:95FD:527C (talk) 21:53, 23 May 2025 (UTC)[reply]

May 23

DMEM (explain the joke?)

https: //mander.xyz/pictrs/image/12b51d24-e090-4a6b-9cf7-b6ec674d99c3.jpeg What is this stuff? Thanks. 2601:644:8581:75B0:A690:D665:179B:79F0 (talk) 12:00, 23 May 2025 (UTC)[reply]

Eagle's minimal essential medium. Not sure about the joke though. I assume it's a single node in some gigantic meme-based causal network i.e. you had to be there. Sean.hoyland (talk) 15:24, 23 May 2025 (UTC)[reply]

The image is a cut-out of a stock photo. The fridge itself is a household fridge, not a typical lab fridge, even though the image is used by a provider of refrigerators that comply with laboratory standards. The posting (of May 19) is on Facebook here. I don't get the joke, but many of the jokes on the user's page are super nerdy, supposed to appeal to people working in biochemistry labs. ‑‑Lambiam 16:00, 23 May 2025 (UTC)[reply]

Thanks all, I suspect none of us are really missing much. 2601:644:8581:75B0:A690:D665:179B:79F0 (talk) 17:39, 23 May 2025 (UTC)[reply]

It probably is a joke about men consuming protein powder to build muscles, but here using an enhanced amino acid growth medium instead. A man is not merely reduced to a body full of muscle, but now to a collection cells. Graeme Bartlett (talk) 02:15, 25 May 2025 (UTC)[reply]

size vs age of universe, name of discrepancy

The universe is supposed to be 13.8 billion years old, while the observable part has estimated radius 90 billion light years. The discrepancy is explained by the expansion of space, particularly during the inflationary period. I'm not asking about the explanation right now. I'm just wondering whether the apparent contradiction has a name, like "so-and-so's paradox". I couldn't find anything about it by clicking in some of the relevant articles. Thanks. 2601:644:8581:75B0:A690:D665:179B:79F0 (talk) 17:38, 23 May 2025 (UTC)[reply]

You can read comoving and proper distances. Ruslik_Zero 20:35, 23 May 2025 (UTC)[reply]

May 25

Why life is a thing in the Universe

I've been reading Abiogenesis and unless I'm mistaken it doesn't answer the question, or maybe I'm reading the wrong stuff. Non-philosophically speaking, is there a point for life in the Universe or it's an unanswerable question? As in, do habitable planets possibly exist for an objective reason? Matt714931 (talk) 13:27, 25 May 2025 (UTC)[reply]

I wonder whether you might be interested in Blaise Agüera y Arcas's work and his book, or the first part anyway. Sean.hoyland (talk) 14:33, 25 May 2025 (UTC)[reply]

It's a question that science can't answer, because there's no way to test any hypotheses about it. Science answers "how", not "why" -- questions of causality, not intent. (When science answers a "why" question like "why is the sky blue?" it's really answering the question of "due to what mechanism", not "for what purpose".) Plenty of people have speculated about the purpose of life, but that's philosophy, not science. -- Avocado (talk) 16:01, 25 May 2025 (UTC)[reply]

One of the few things philosophers and scientists agree on is that asking for the meaning of life, the universe, and everything, is not within the province of science. This applies not only to the question, "what does it all mean?", but even to the question, "does it mean anything?". ‑‑Lambiam 21:52, 25 May 2025 (UTC)[reply]

@Matt714931. Unfortunately we don't yet have a philosophy reference desk, and we are not supposed to speculate here, but we do have an interesting article on the meaning of life. Shantavira|^{feed me} 16:52, 25 May 2025 (UTC)[reply]

Actually, the Humanities desk is supposed to cover philosophy anongst other areas, but of course it's for answerable questions, not extended discussions of unresolved ones. {The poster formerly known as 87.81.230.195} 90.193.154.147 (talk) 23:29, 29 May 2025 (UTC)[reply]

As I stated I was looking for an "non-philosophically speaking" (and especially anthropocentric) answer. Maybe I didn't phrase it correctly, I'm more looking into finding out theories as to why there is life at all, when it does not seem to change anything (no relationships) from the standpoint of Existence, i.e. the Universe. Things were around before the Earth was habitable and things are going to be around after. The conumdrum is even bigger if we're indeed a biological rarity. Whether the Earth is a barren crater or not doesn't seem to change anything. Matt714931 (talk) 18:17, 25 May 2025 (UTC)[reply]

You might as well ask "what is the point" of the universe itself. There's nothing in science that requires there to be a "point" for the existence of something. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:27, 25 May 2025 (UTC)[reply]

Why there is life at all could be because it is inevitable. At the very least, it changes the amount of computation and complexity, locally anyway. Sean.hoyland (talk) 18:31, 25 May 2025 (UTC)[reply]

Oh, you said anthropocentric ... there's the Anthropic principle which says that we can't observe the absence of life since that would entail the absence of us. Physics presumably doesn't entail life, so far as we know. This depends on how likely life is, which is an open question. Card Zero (talk) 21:44, 25 May 2025 (UTC)[reply]

The deeper question is Why is there anything at all?. DMacks (talk) 00:13, 28 May 2025 (UTC)[reply]

The Creator is uber-Trumpian in his Supreme Narcissism. He requires there to be sentient beings to adore and worship Him forever. Rocks and gases can't do that, so we're the next cab off the rank. -- Jack of Oz ^{[pleasantries]} 18:59, 25 May 2025 (UTC)[reply]

The purpose of life is to keep the Supreme Fascist’s "score" low by acting in good conscience.^[1] ‑‑Lambiam 21:43, 25 May 2025 (UTC)[reply]

Abiogenesis (the origin of life) remains a mystery, and the mechanisms of how organisms arise naturally from non-living matter remain controversial. Scientists are generally believed that life on Earth originated from a series of chemical reactions that gave rise to complex molecules, which then evolved into self-replicating systems and eventually cells. If this process can occur on Earth, then it should be able to occur anywhere in the universe given the right conditions. Stanleykswong (talk) 06:30, 31 May 2025 (UTC)[reply]

May 29

Extended Gaumt vision?

https://www.youtube.com/shorts/hd2XrjFBXW0

The research mentioned appears to relate to using direct stimulation of cones.

Does anyone have a direct citation for the relevant paper ( if published) ?

The approach also got me thinking, various anecdotal accounts of the impacts of pharmacological effects of certain psychidelics have allegedly included increased or more vivid colors. What papers constitute a reasonable basis for explaining this mechanism, that could be used as a basis for determining if pharamocological influences, can create an enhanced cone simulation or response, simmilar in effects (although not mecahnism) to the laser 'microdose' technology developed by UC Berkely?

ShakespeareFan00 (talk) 10:09, 29 May 2025 (UTC)[reply]

"Novel color via stimulation of individual photoreceptors at population scale".^[2] ‑‑Lambiam 19:30, 29 May 2025 (UTC)[reply]

May 31

More BS about Amelia?

Is there any substance to recent reports that Amelia Earhart's plane allegedly may have been found? In other words: did they actually find any plane debris at all, and if so, what type of aircraft did they find? (I'm asking this because I've seen a number of recent videos alleging to have found Amelia's plane, but all of those videos showed planes of the wrong type -- for example, one showed the remains of what looked to me like a Junkers 52, and another showed a largely intact plane which could be an Ilyushin Il-14 or Saab 90 Scandia or similar, but was in no way, shape or form even remotely like an Electra 10-E!) 2601:646:8082:BA0:20FE:78DB:A092:17F4 (talk) 08:27, 31 May 2025 (UTC)[reply]

The rumors are based on this Instagram post of January 27, 2024 by deep water exploration company Deep Sea Vision, who spotted an anomaly said to be shaped like the Lockheed Model 10 Electra, at a location that is not implausible under a new theory of a navigational error. In this article we can see (in the last illustration) an image of the anomaly next to a representation of the Lockheed. Personally, I find the similarity less than convincing. ‑‑Lambiam 10:14, 31 May 2025 (UTC)[reply]

I agree. It looks more like Earhart's jet, the one with swept-back wings. Clarityfiend (talk) 12:11, 31 May 2025 (UTC)[reply]

I concur -- the image looks to me more like a Chance-Vought F7U Cutlass or a Grumman F-9 Cougar, which BTW both happen to be about the same size as the Electra -- and given that our Navy has always (since at least the 1930's) performed carrier operations pretty much everywhere in the Pacific Ocean, and that carrier operations are inherently dangerous, it's very plausible that they might have lost one of those in that area! (In any case, I'm pretty sure there are more than enough aircraft of all kinds on the bottom of the Pacific to start an undersea airline!) 2601:646:8082:BA0:1DA0:4169:3D3F:16BA (talk) 21:28, 31 May 2025 (UTC)[reply]

The aircraft is unlikely to be completely intact, regardless of what it is. It would have to have survived a controlled ditching (at best), followed by impact with the seabed when it sank, and then all the effects of corrosion etc that lead to breakup of objects in the sea. The apparent 'sweep' could be the result of any of that. Certainly the image lacks anything like the detail to say for sure that is an Electra, but likewise, taking into account the likely damage, it would seem unwise to say definitively that it isn't. Anyway, we aren't being asked to pay to send an ROV down to take a look. If anyone does, we'll find out one way or another. AndyTheGrump (talk) 21:47, 31 May 2025 (UTC)[reply]

Earth radioactive decay contribution in Sankey diagram

The flow diagram I once drew shows that the energy arriving at the Earth balances the energy leaving, as per its references.

As the Earth produces its own heat through radionuclide decay, shouldn't there be a flow coming in from elsewhere to join the flow "Radiated to space"? Is it negligible, or already lumped into "Absorbed by ground"?

Thanks, cmɢʟee⎆τaʟκ 08:28, 31 May 2025 (UTC)[reply]

The total solar irradiance is about 1361 W/m². To get the incoming energy from the Sun, this needs to be multiplied by the cross-sectional area of Earth, about 127×10¹² m², giving about 173×10¹⁵ W.

According to our article Earth's internal heat budget, the flow of heat from Earth's interior to the surface (which comes in roughly equal amounts from the radiogenic heat and the primordial heat left over from the formation of Earth) is estimated to be no more than 49×10¹² W. This is less than 0.03% of the total budget, indeed a negligible fraction. It is, however, significant on the Earth's energy imbalance of about 460×10¹² W, although, AFAICS, not accounted for in ref 1 of the article Earth's energy budget. ‑‑Lambiam 09:46, 31 May 2025 (UTC)[reply]

Thanks very much for doing the maths, Lambiam. Guess no change is needed to the diagram then. cmɢʟee⎆τaʟκ 09:42, 1 June 2025 (UTC)[reply]

Butia odorata or Butia capitata

If you know about Butia palms, please see c:Commons:Village pump#Butia_odorata_or_Butia_capitata. File:Butia capitata Madrid.jpg is titled and captioned as Butia capitata, but it is presented on Butia (and commons:Category:Butia odorata any many other pages) as Butia odorata. I wasn't sure where the best place to report this was, so I've gone with reporting it on Commons and posting this notification here. -sche (talk) 20:19, 31 May 2025 (UTC)[reply]

A possibly relevant comment from 2018: Talk:Butia capitata § This article is actually about another species. Note, though, that File:Butia capitata Madrid.jpg was not used on page Butia capitata, but File:Butia capitata, Tresco.JPG – which the commenter replaced with the current image. ‑‑Lambiam 05:31, 1 June 2025 (UTC)[reply]

June 1

[1] t my mother's knee

[1]