Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

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.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

February 14

Wheelchair accessibility info on wikipedia

Does Wikipedia include information about whether a travel site is or is not wheelchair accessible? If so, how do I find that information? Aggroch (talk) 22:34, 14 February 2023 (UTC)

If such information is available on Wikipedia at all, it is likely to be in the relevant article for any facility, if we have an article on it. I'd strongly recommend not relying on such information though, as articles aren't intended as travel guides, and nor are they necessarily updated with any regularity. You would do better to check with the facility itself, where possible. AndyTheGrump (talk) 22:43, 14 February 2023 (UTC)

You might want to look at Wikivoyage. I don't know how much information it provides; I only know about it because its "tourist office" page is linked from the Reference Desk. --174.89.12.187 (talk) 23:20, 14 February 2023 (UTC)

February 15

Butterflies of Maine

Is the Eastern tiger swallowtail (Papilio glaucus) native to Maine, or not? According to greennature.com and butterflyidentification.org, it is found in Maine, but a county-by-county search on factsaboutbutterflies.net did not find it even in York County, Maine (the southernmost county in the state). So which is it? (No pictures please -- I am not searching because I want to find it, I am searching because I do not want to find it, this being the only butterfly species in the Northeast region which causes a phobic reaction on my part, so I don't want to see it until I've desensitized myself through multiple close encounters with P. canadensis!) 69.181.91.208 (talk) 07:45, 15 February 2023 (UTC)

That sounds like a very specific phobia if exposure with canadensis is acceptable (from the article Papilio canadensis [it] was once classified as a subspecies of Papilio glaucus, and the pictures are strikingly similar). Assuming you are not a troll, you need a therapist, not an entomologist. Tigraan^{Click here for my talk page ("private" contact)} 10:49, 15 February 2023 (UTC)

He's probably not a troll, he's asked similar questions before. The problem is one of defining "range". In birds you have the resident range, the breeding range, and the non-breeding range. The breeding range, in the case of butterflies would be where their caterpillars are found, and usually this range is demarcated rather conservatively; only where the species is successfully breeding every year. Individual adults may fly or get blown far from their breeding range, and even if they managed to mate and lay eggs, their offspring might be too far north and be doomed to die in the winter. So I would say that one would have to know if the websites above require caterpillars to be observed to list the species as being "from" York County. Alternately, maybe York County is the furthest north an Eastern tiger swallowtail adult has ever been observed. Abductive (reasoning) 11:16, 15 February 2023 (UTC)

The Maine Species List from the Maine Butterfly Survey, conducted between 2006 and 2015, via this page which calls it Pterourus glaucus glaucus says it is RC (Rare temporary colonist)/ST (stray). So apparently not native and you are unlikely to see it. MinorProphet (talk) 01:34, 16 February 2023 (UTC)

Thanks! And yes, I know that P. canadensis and P. glaucus are very similar in appearance (as, indeed, are all of the tiger swallowtails except P. eurymedon), except in terms of size -- and that is why P. glaucus scares me but P. canadensis doesn't, because it's quite a bit smaller (its maximum size is about 3 1/4 inches, and that's just below my threshold for phobic response (for butterflies with vertical stripes only --those that lack such stripes, such as P. troilus, don't scare me even at 4 inches of wingspan) -- as I've established for myself through my own original research!) 2601:646:8A81:6070:75FB:9B75:3F50:7236 (talk) 02:39, 16 February 2023 (UTC)

STEPHEN C. MEYER

HELLO. I REVIEWED A WIKIPEDIA ARTICLE ON STEPEN C. MEYER. IN THE ARTICLE IT STATES THAT PROFESSOR MEYER IS A PROPONENT OF THE PSEUDOSCIENCE OF INTELLIGENT DESIGN. QUESTION: IF THE SCIENTIFIC EVIDENCE SUGGESTS INTELLIGENT DESIGN WHY IS THAT CONSIDERED PSEUDOSCIENCE? THANKS FOR CHECKING. BRYON GORTON OFALLON,ILLINOIS. 99.177.221.45 (talk) 18:27, 15 February 2023 (UTC)

Hello Bryon. Just a quick note: Please don't write in ALL CAPITALS. In written communication, all capitals reads like your screaming, so please don't do so. It can be read as rude. Secondly, the consensus is that intelligent design is pseudoscientific, which means that while it presents itself as a scientific theory, using the language of, and some of the superficial trappings that actual science does, that it has never stood up to rigorous scientific analysis. As noted at pseudoscience, "Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable claims; reliance on confirmation bias rather than rigorous attempts at refutation; lack of openness to evaluation by other experts; absence of systematic practices when developing hypotheses; and continued adherence long after the pseudoscientific hypotheses have been experimentally discredited." That describes the status of intelligent design. --Jayron32 18:38, 15 February 2023 (UTC)

To put it more directly (reduce Brandolini's law impact), the statement "the scientific evidence suggests intelligent design" is not scientifically correct, therefore nothing based on that premise has scientific validity. DMacks (talk) 18:52, 15 February 2023 (UTC)

Supposed "evidence" for intelligent design generally is not actually evidence, but rather fallacies or absence of evidence. For example, the argument of "irreducible complexity" usually designates things as irreducible when, in fact, they are reducible. The eye is the classical example; while separate components that make up the eye do need to all be there for the eye to function precisely as it currently does, that doesn't mean that those components have zero function separately. For example, the light receptor protein (rhodopsin) has many uses outside of the function of the eye and, in fact, we have found this protein in these uses throughout nature. In the example of the rhodopsin, we have things like Channelrhodopsin proteins which are light sensitive. They may not function as an eye per se, but they do have a function and work quite well for it, and then can be adapted to form a primitive eye (such as an eyespot). Another form of "evidence" for intelligent design is the fallacious "gaps" (or God of the gaps) argument. This is the absence of evidence form of "evidence." Basically, it can be described as "we don't know how this evolution step or formation of life step happened, so therefore an intelligent designer (God) did it." Our lack of knowledge or understanding of something is not scientific evidence for an intelligent designer or a god. It's literally just "we don't know this," and that's it. Maybe, in the future, we will find actual evidence that step was done by an intelligent designer (or God), and maybe we will find the natural explanation that doesn't involve an intelligent designer (or God). To date, the pattern of discovery has gone towards the natural explanation 100% of the time, and there is little reason to expect that to change (though that pattern is also not evidence that something we don't yet know wasn't an intelligent designer or God, just that it isn't likely the answer, when discovered, will be intelligent design or God). --OuroborosCobra (talk) 19:22, 15 February 2023 (UTC)

Irreducible complexity is fancy speak for 90% "I'm not personally smart enough to understand this" and 10% "Not every single thing is entirely known now, so the entire thing must be fake". --Jayron32 12:02, 16 February 2023 (UTC)

All too true and Stephen C. Meyer even has a Ph.D. in the philosophy of science from the University of Cambridge. Hmm. Intelligent design is religion so it makes sense the guy studied and embraced it, not a fruitful endeavor IMHO. Modocc (talk) 14:01, 16 February 2023 (UTC)

As an old math teacher once said to our class, "If you start with incorrect assumptions, you're likely to get 'interesting' results." ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:15, 16 February 2023 (UTC)

To some extent, sure, but in science, that initial assumption should itself be falsifiable and tested. This might be more difficult to do in mathematics, but in science, it is usually easily (relatively speaking) done. For example, the assumption that the human eye is too complex to arise through evolutionary processes and that its components cannot function independently of each other is testable (see my earlier comment about rhodopsins, channelrhodopsins, and eyespots, for example). Testing that hypothesis shows it to be false. --OuroborosCobra (talk) 17:22, 16 February 2023 (UTC)

Every slipped disc, fallen arch, and pot belly is proof that any putative designer could not have been very intelligent. Those problems exist because a basic mammalian quadrupedal anatomy has been rather awkwardly repurposed into a bipedal form and has not been properly modified for it. Such biological "spit and baling wire" solutions make sense in an evolutionary context but not an ID one.--User:Khajidha (talk) (contributions) 12:47, 17 February 2023 (UTC)

The ID proponents would likely say that's because of Adam and Eve's original sin, fall from grace, etc. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:26, 17 February 2023 (UTC)

To make this into a scientific argument (which this thread is about), we need a little scientific experiment. Recreate the heaven and the earth, but this time with a minor twist: we muzzle the serpent so that it cannot tempt the woman to eat the forbidden fruit. Wait another 60 centuries or so, and test the hypothesis that there are significantly fewer slipped discs than on the current earth.  --Lambiam 11:25, 18 February 2023 (UTC)

Reminds me of something Carl Sagan said on Cosmos: "If you wish to make an apple pie from scratch, you must first invent the universe." ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:16, 18 February 2023 (UTC)

A stronger argument against intelligent design than potbellies is the blind spot in the vertebrate eye, caused by the wiring (nerve fibres) from the retina to the brain running on the inner side of the eye. This is not by some engineering necessity, since the wiring runs along the outer side in the cephalopod eye. Given how natural evolution leads to optimal designs, this can be seen as an argument for creation by stupid design: the universe was apparently created as homework by an inept demiurge apprentice.  --Lambiam 11:36, 18 February 2023 (UTC)

Relativity and everything's moving

Sorry if this is all answered somewhere; it's so far above me that I don't know where to look.

If I correctly understand little bits of special relativity: for an object at rest, time passes at such-and-such a speed and the object has such-and-such a mass, but when the same object is moving, time gets slower and mass increases in proportion to the speed. But of course, an object at rest on Earth isn't quite at rest; it's rotating Earth's axis, orbiting the Sun, orbiting the galactic centre, and probably other things too. Is it possible to account for all motion (and thus calculate the mass and speed-of-time-passing for the same object if it weren't moving at all), and if it's not, how can special-relativity-based calculations function? I suppose you could pretend that Earth is stable, and calculate everything relative to terrestrial motion, but such an assumption wouldn't work for space travel, and while I know that special relativity has no naked-eye-observable effects, I don't suppose that physicists prefer to rely on "that's too small to care about". When an object's speed is X percent of the speed of light, and this percentage is critical to certain aspects of its behaviour and nature (e.g. mass and speed-of-time-passing), I don't see how you can calculate anything without roughly knowing the actual ratio of the object's speed and the speed of light. Nyttend (talk) 20:12, 15 February 2023 (UTC)

"if it weren't moving at all" is where you come unstuck. There is no absolute stationary frame of reference. Provided you are not accelerating or rotating, you yourself define a frame of reference that can be considered as "not moving at all". Other objects are in movement relative to your frame of reference, and the relativistic changes can be calculated on that basis. But you yourself are moving relative to their frame of reference, so from their point of view you will be experiencing shortening, increased mass, and time dilation. You can't escape.

The 'gotcha' is that the speed of light is apparently the same in all frames of reference; it is from this observation that the 'distortions' suffered by objects moving relative to yourself can be calculated. -- Verbarson  ^talk_edits 20:43, 15 February 2023 (UTC)

The speed that is relevant is not a property of the moving object. It is its speed relative to an observer. Observers are always at rest relative to themselves. If two observers pass each other at a very high constant speed in identical vehicles with visible clocks, each will observe the other's vehicle as being shorter and its clock as moving more slowly than their own.  --Lambiam 21:25, 15 February 2023 (UTC)

"if it weren't moving at all" Even weirder. But that's much easier to understand, at least. apparently the same in all frames of reference So if a spaceship going 1% of the speed of light emits beams of light directly ahead of itself and directly behind itself, the spaceship will see the beams going the same speed as each other, rather than one appearing to go 99% the actual speed of light and the other 101% the actual speed? Nyttend (talk) 22:34, 15 February 2023 (UTC)

In theory, according to relativity, yes, the light is said to always travel at the same speed c in every inertial reference frame and there is an enormous amount of literature regarding SR covered in the relevant articles and SR's relativistic Doppler effect holds for all inertial reference frames as well. But clocks can and do interact at different rates. For example, the atomic clocks flown westward in the Hafele–Keating experiment gained time relative to the "stationary" terrestrial clocks such that the planes' and terrestrial's clocks interacted at very different rates. Of course, the westward flown clocks that ticked faster traveled slower than the Earth's rotation relative to the Milky Way. This interesting fact even holds, as it should, if the curvature k of their trajectory tends to zero. Modocc (talk) 23:19, 15 February 2023 (UTC)

Thank you; this really helps. I knew that one can never reach the speed of light, but I figured it was an effect of go-faster-mass-increases (you'd end up with infinite mess, so you'd need infinite energy) and had no idea that light always goes away from you at the same speed, no matter how fast you're going. Nyttend (talk) 00:46, 16 February 2023 (UTC)

The 99% and 101% numbers you give seem to suppose that velocities combine via simple addition. You may be interested to learn that according to Special Relativity, this is not the case. If you are traveling at speed x relative to an observer, and you throw a ball forward at speed y relative to yourself, the observer does not see the ball traveling at speed $x+y$, but rather at ${\frac {x+y}{g}}$, where $g=1+{\frac {xy}{c^{2}}}$. When velocities x and y are small compared to c as they usually are in everyday life, $g$ is close to 1, and the difference between $x+y$ and ${\frac {x+y}{g}}$ is small, so the naive velocity addition formula ($x+y$) seems to work, although it's wrong.

This formula predicts that the combination of c with any velocity x will be simply c, since
${\frac {x+c}{g}}={\frac {x+c}{1+{\frac {xc}{c^{2}}}}}={\frac {x+c}{1+{\frac {x}{c}}}}={\frac {x+c}{\frac {x+c}{c}}}=c$, so light travels at c relative to any observer. CodeTalker (talk) 06:30, 16 February 2023 (UTC)

The OP, Nyttend, understood. He said "...the spaceship will see the beams going the same speed as each other, rather than..." their example of a Galilean invariance and thanked me for clarifying that is precisely what SR claims. Modocc (talk) 11:41, 16 February 2023 (UTC)

I however don't understand how a spaceship can be expected to "see" a difference in one-way velocities of light beams that it emits in different directions. Can a traveller on the spaceship devise a way to test that? It's no use asking Messrs. Michelson and Morley whose oft repeated and refined experiment hasn't found a difference since 1887. Philvoids (talk) 19:03, 16 February 2023 (UTC)

Michelson and Morley are dead, so we can't ask them, but when they built their interferometer on spaceship Earth, they expected to see a difference.  --Lambiam 11:46, 17 February 2023 (UTC)

• So, Philvoids tangent at the bottom is actually rather important point; enough to bear dealing with in some detail. His sentence "I however don't understand how a spaceship can be expected to "see" a difference in one-way velocities of light beams that it emits in different directions", this brings up the excellent point that there is no way to measure the One-way speed of light, which is to say, the speed of light moving away from the observer OR the speed of light moving towards the observer. One can only measure the "round-trip speed of light". Lets say you are on a spaceship traveling from Earth to Mars, and are oriented such that Earth is directly behind you and Mars is directly in front of you. If you shine a light out of the back of the ship and shine a light out of the front of the ship, the only way to measure the speed of those light beams is to wait for them to bounce off of a target, and return to the ship. If light was moving faster going backwards, and slower going forwards, you'd never know, because on the return trip, the beam is moving in the opposite direction, so that difference in speed perfectly cancels every single time, no matter how you do the experiment. Veritasium, a few months back, did an excellent video on the problem.[1]. If there was some fundamental property of the universe that gave light a greater velocity in some absolute direction, and a lower velocity in opposite direction, like some kind of "ethereal wind" that only affected the speed of light, you'd never be able to know, because any trip that light takes to get back to the observer so its speed can be measured would always have vectors that exactly cancel in a way to make any such putative effect obscured. It's a real problem that we always gloss over; the Occam's razor explanation is that there is no such difference, however, Occam's razor is not a scientific proof, just a "rule of thumb", and science depends on more than such things. --Jayron32 19:22, 16 February 2023 (UTC)

Philvoids tangent is fair enough. Indeed, all observers can take selfies, which wouldn't be any different than current measurements of c. -Modocc (talk) 21:35, 16 February 2023 (UTC)

You have to have rather strange laws about how clocks change when moved slowly in one direction compared to another. There's no need to go on about one way measurement of the speed of light here, it's supposed to be about trying to answer the OP, and if Einstein was happy with his way of doing it then it is good enough for the OP. NadVolum (talk) 21:58, 16 February 2023 (UTC)

The laws aren't all that strange. Lorentz transformations have been well known, understood, and confirmed by measurement for more than a century. Also, Einstein was well aware of the problems with the one-way speed of light. Einstein synchronisation was an arbitrary convention he established, he was well aware it could never be proven to be true, merely acceptable. --Jayron32 23:06, 16 February 2023 (UTC)

The laws do change considerably, for instance you have to consider time dilation even when moving slowly. Einstein was just being sensible doing what he did. It is worthwhile trying to see if there might be holes in a theory - but something that's more complicated and does nothing for insight is no good here. This is all just irrelevant to the OP's question. NadVolum (talk) 14:19, 17 February 2023 (UTC)

I know that the speed of light was measured centuries ago, but I don't understand how it was done, let alone how it's done with current equipment or could be done with equipment that's invented by the time that 0.01c spaceships would be invented. Interesting to know that you can't measure its one-way speed. Nyttend (talk) 00:27, 18 February 2023 (UTC)

@Jayron32

"If you shine a light out of the back of the ship and shine a light out of the front of the ship, the only way to measure the speed of those light beams is to wait for them to bounce off of a target, and return to the ship."

You could of course measure the light from inside the spacecraft if you wanted.

"If light was moving faster going backwards, and slower going forwards, you'd never know."

Light travels at the same speed in both directions. It's the frequency of the light that changes. Earl of Arundel (talk) 02:08, 19 February 2023 (UTC)

For whom does the frequency change? Doppler effect does not happen for an observer inside the spacecraft who is moving with the light source. Philvoids (talk) 21:01, 19 February 2023 (UTC)

1) How do you measure the speed of light inside the spacecraft? Like, give me a procedure. 2) How do you know light goes the same speed in both directions? Can you point to an experiment which has verified that? --Jayron32 13:28, 20 February 2023 (UTC)

I think that the nearest we have is the Wu experiment. Many scientists would invoke symmetry (physics) and not seek experimental verification. Mike Turnbull (talk) 13:49, 20 February 2023 (UTC)

The Wu experiment was not a measure of the speed of light. Yes, everyone is well aware that you can just invoke a principle. I mentioned Occam's razor above, however, no experiment has ever been done which established the one-way speed of light. --Jayron32 13:55, 20 February 2023 (UTC)

February 18

Tuna fins and scales

Wondering whether tuna were kosher, I ran a Google search and found blurbs from sites saying that some varieties are, and some aren't. However, I've tried to load several such sites, and either they won't work (maybe they don't like my IP address?), or they don't appear to answer the question...so I come here instead. Are there big differences from one tuna species to another, to the point that some species don't meet the basic kosher requirement of "fins and scales"? Or are all species rather similar, and the kosher status depends on some smaller aspect of Jewish law? Nyttend (talk) 01:51, 18 February 2023 (UTC)

It could depend on what they feed on. For example, as I understand it, catfish are not kosher because they are "bottom feeders". ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:25, 18 February 2023 (UTC)

Well, that's one of those "some smaller aspect of Jewish law" things. [Next sentence sounds like a complaint, but it's not.] I came here, not RDH, because I wanted to ask about the tuna-anatomy issue instead of halakhic interpretations. Nyttend (talk) 03:44, 18 February 2023 (UTC)

According to this article,[2] tuna are considered kosher. The issue seems to be in the preparation of them. With canned tuna, it can be uncertain whether kosher laws were followed in the preparation. ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:00, 18 February 2023 (UTC)

[Edit Conflict] Tuna and the individual species linked from it will have a good deal about the anatomy of the 15(-ish) species, but you probably knew that. Skipjack tuna seems to be the species with fewest (but not no) scales. {The poster formerly known as 87.81.230.195} 51.198.55.125 (talk) 07:06, 18 February 2023 (UTC)

Here is an informative article about tuna species and their scaliness, which has a considerable variation between species. The scales of a fish need to be discernible by the unaided eye for it to be considered having scales in halakhic law. This disqualifies several tuna species. Eels also actually do have scales, but since you can't see them, they are not kosher.  --Lambiam 15:04, 18 February 2023 (UTC)

Do microwaves need to be calibrated over time?

Microwaves give off 2.45 GHz radiation, from the magnetron. What would cause it to have some failure where it starts giving off slightly different radiation, like 2.46 or 2.44 GHz? Should microwaves even need to be calibrated over time? Weird trivial question lol. 67.165.185.178 (talk) 14:18, 18 February 2023 (UTC).

The frequency of a microwave is the resonant frequency of the arrangement of the cavities of its magnetron, which is determined by their physical dimensions. Since the magnetron consists of a large, solid cylinder of metal in which cavities are drilled, one would need an extraordinary force to deform it so much that these physical dimensions undergo an appreciable change. After it has been run over by a steam roller, one's microwave may be in need of calibration – but if it is still operating, albeit at a slightly different frequency, like 2.46 or 2.44 GHz, one need not worry – these frequencies will do the job just as well.  --Lambiam 15:15, 18 February 2023 (UTC)

Magnetron frequency drifts for a number of reasons:

• The load on the magnetron (frequency pulling); the operating frequency is a resonance of the whole system, consisting of the magnetron cavities and the external circuit (the oven cavity, the food and any mode-stirrer). The arrangement of the external part is by design randomized by rotating the food and/or mode-stirrer.
• Temperature; the frequency drops as the anode heats up and the cavities expand.
• The current through the magnetron (frequency pushing); the presence of electrons in the magnetron changes the resonant frequency.

Even if the magnetron can be considered as a perfectly isolated and empty cavity, there exist an infinite number of resonant modes with different frequencies. The wanted mode is the π-mode, where alternating individual cavities oscillate in antiphase. However, when the magnetron is switched on or off, the applied voltage may briefly be such as to allow the excitation of other modes.

For regulatory compliance, it is sufficient for the oven to operate at between 2.4 and 2.5GHz. catslash (talk) 19:16, 18 February 2023 (UTC)

The OP uses every-day speech "microwaves" to refer to a consumer Microwave oven. For safety these ovens are designed to leak (give off) least possible of their internal electromagnetic radiation intended to heat food. The internally generated frequency of nominal 2.45 GHz (wavelength of 12.2 cm 4.80 in) is not exact or stable because the low-Q resonant-cavity magnetron drives the poorly-matched food cavity that rotates the food to avoid uneven heating by persisting standing waves. This video shows frequency spectrum of stray emission of an oven. To allow for this variation the FCC allocates a 100 MHz bandwidth 2.40 to 2.50 GHz for ISM (Industrial, Scientific and Medical) use. Excessive radiation leakage in this range or any radiation outside the band are both avoided by design; the latter is important because there are nearby frequency allocations for mobile communications, including IMT-2000/UMTS, mobile satellite communications, weather/ship radar, Bluetooth, Wi-Fi, Zigbee and other technologies, see What is the S Band?. Philvoids (talk) 20:10, 18 February 2023 (UTC)

Transformers questions.

1. Transformers are to increase or decrease the voltage. Called step-up or step-down. Since voltage is inversely connected with current, then can we safely say transformers are also to increase/decrease the current? Yet no 1 seems to define it that way.

2. Transformers tend to have an oil fluid around it due to heat given off. As oil is heated, oil expands, and transformers have areas where oils can move into. So what causes more of heat, step-up, or step-down? (Voltage.). Thanks. 67.165.185.178 (talk) 14:22, 18 February 2023 (UTC).

(1) Transformers can also be 1:1 for isolation purposes. You're right in your assumption, in a perfect transformer Vin×Ain = Vout×Aout. (2) Transformers are unfortunately not perfect. Expanding the equation we get: Vin×Ain = Vout×Aout + Wloss The size of W depends upon many factors in the design of the transformer. W is dissipated as heat. See transformer for a more erudite explanation. Martin of Sheffield (talk) 14:31, 18 February 2023 (UTC)

Okay, so it looks more likely, a big increase in voltage/current are a big increase in heat given off, so either direction (step up or step down) will do. 67.165.185.178 (talk) 14:47, 18 February 2023 (UTC).

The length of the handles of a pair of pliers is connected with its gripping force. You can increase the force by extending the handles. You cannot extend the handles by increasing the force. Same with the voltage–current relation. Given the load, you can increase the current by increasing the voltage. You cannot increase the voltage by increasing the current.  --Lambiam 15:26, 18 February 2023 (UTC)

So if you increase the current, voltage is decreased? Where watts is still the same? 67.165.185.178 (talk) 18:20, 18 February 2023 (UTC).

Current is simply a measure of "flow rate". You cannot increase it without either (A) increasing voltage or (B) decreasing resistance, so it really doesn't make sense to talk about "increasing current" as if it were some kind a "tunable parameter" per se. Earl of Arundel (talk) 19:42, 18 February 2023 (UTC)

OK, here is a worked example. I'm going to assume that the transformer is perfect, that is has no losses. Clearly this is not true, but it keeps the explanation simple. Assume that there is a mains input and a 12V output with a 1.2 ohm resistor connected across the output. The output circuit will therefore draw 10A (from V=IR). This gives a Vout×Aout of 12 × 10 = 120 VA. To supply this we need Vin×Ain to also equal 120, therefore 240 × A = 120 or the current drawn from the mains socket is 0.5A. As Earl of Arundel points out, this is controlled by the 12V output and the 1.2Ω resistor. The transformer simply transforms the input and output so that 12 × 10 = 240 × 0.5. Martin of Sheffield (talk) 21:06, 18 February 2023 (UTC)

If you increase the resistance of the output the voltage will not change much but the current will decrease. This is why we think of it as changing the voltage. The maximum current one could have when reducing the resistance will be set by the supply and the size of the transformer. NadVolum (talk) 21:33, 18 February 2023 (UTC)

@NadVolum: but have you considered current transformers whose characteristics are such that the output voltage rises until the wanted current flows (within rather strict limits)? Martin of Sheffield (talk) 22:29, 18 February 2023 (UTC)

They are used for measuring current, there is no wanted current. NadVolum (talk) 11:30, 19 February 2023 (UTC)

Okay 1 thing I am stuck on, as current is the flow of charge. Which are electrons, and flow of electrons induce an electric and magnetic field. What if the particles were instead, protons? And you have proton-electricity. What kind of a field does that induce? And to make it more complex, protons are H+ ions. Which is synonymous with acid. So now it has a pH. ;d 67.165.185.178 (talk) 14:02, 19 February 2023 (UTC).

It would make no difference if the protons move in thw opposite direction to the electrons. The + and - of electricity were chosen at random before anyone knew about electrons, it would have made more sense to have had the electrons be + and be moving to the -. NadVolum (talk) 16:18, 19 February 2023 (UTC)

It would not be easy to create a flow of protons. Perhaps you mean positrons. See als Dirac hole theory. For the purpose of understanding conventional electric circuits, the magnetic component of the electromagnetic field can usually be ignored – but obviously not in the operation of transformers or electromagnets such as found in electric motors.  --Lambiam 17:10, 19 February 2023 (UTC)

Exactly. A proton is almost 2000 times more massive than an electron. Good luck pushing a single amp's worth through a conventional circuit. That said, it would be interesting to see if a coiled tube of flowing acid could generate any appreciable inductive effects (or say, a proton-powered solenoid). Earl of Arundel (talk) 18:43, 19 February 2023 (UTC)

Even with an electric stove working full pelt at home the electrons would only be moving on average somethng like half a millimeter a second. Pretty surprising when you consider how fast the lights turn on! NadVolum (talk) 20:14, 19 February 2023 (UTC)

The electrons in a circuit being closed start moving at (almost) the same time. It is not as if they are pushed forward by those behind them bumping into them.  --Lambiam 23:53, 19 February 2023 (UTC)

Just as a data-point, GeV-range particle accelerators seem to be commonly generating proton beams of a few 10s of mA. That's not a bad way to cook a tumor, but pretty bad to make a pot of tea. DMacks (talk) 20:43, 19 February 2023 (UTC)

While some acids contains protons (as H⁺ ions), they contain an equal number of negatively charged conjugate-base ions that flow at the same rate in the same direction, so the net effect of flowing acid is not an electric current.  --Lambiam 23:50, 19 February 2023 (UTC)

Proton conductors do exist. There are also solid lithium ion (and other ion ) conductors, even including a silver ion conductor. Graeme Bartlett (talk) 07:52, 20 February 2023 (UTC)

February 19

The Maimonides position about the semen and intercourse is supported by the science?

I came across Mimondes' position about semen and intercourse, and it is interesting for me if it is supported by science, or it is anachronistic and not up to date? Here is what he says (Human dispositions 4,19):

"Semen is the strength of the body, its life [force], and the light of the eyes; the greater the emission [of sperm], [the greater] the damage to the body, to its strength, and the greater the loss to one's life [span]. This was implied by Solomon in his wisdom: "Do not give your strength to women" (Proverbs 31:3 . Whoever is steeped in sexual relations, old age springs upon him [before its time], his strength is depleted, his eyes become dim, a foul odor emanates from his mouth and his armpits, the hair of his head, his eyebrows, and eyelashes fall out, the hair of his beard, armpits, and legs grows in abundance, his teeth fall out and he suffers many pains beyond these. The wise of the doctors have said: One of a thousand dies from other illnesses and a thousand from excessive intercourse."

--ThePupil (talk) 01:15, 19 February 2023 (UTC)

We don't seem to have an article that character. But it sounds like he was the inspiration for General Jack Ripper. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:59, 19 February 2023 (UTC)

The "character" is Maimonides, the passage is from Mishneh Torah. I've had some difficulties trying to understand the structure of the thing, but it appears to be in the first book (HaMadda), section 2 (De'ot), and there in the 19th paragraph of chapter 4, see e.g. [3] or [4]. --Wrongfilter (talk) 09:35, 19 February 2023 (UTC)

It helps when the OP spells it right. Well, that's an interesting read. On some things he may be right, on others he missed the boat. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:13, 19 February 2023 (UTC)

(ec) No, this is not supported by science -- frequent sexual intercourse does not, in and of itself, harm the body (unless one catches venereal disease, which is a different matter altogether!) 2601:646:8A81:6070:21B3:46A0:D94F:FF3B (talk) 02:04, 19 February 2023 (UTC)

Oh, and for evidence, see Sexual_intercourse#Health_effects. 2601:646:8A81:6070:21B3:46A0:D94F:FF3B (talk) 02:07, 19 February 2023 (UTC)

While Maimonedes was surprisingly scientifically enlightened for the 12th century – the various authors of Proverbs (Ch 31 vv 1–9 are attributed to Lemuel (biblical king), not Solomon) in the 1st millenium BCE perhaps less so – such pronouncements around sexual activities are almost invariably concerned with social and moral control, rather than literal medical facts. Did your parents ever tell you that eating pure sugar gives one worms, or sitting on a radiator gives one piles? (Mine did.) Did you believe them then, and do you believe it now? {The poster formerly known as 87.81.230.195} 51.198.55.125 (talk) 02:39, 20 February 2023 (UTC)

I never did reconcile "sitting on a radiator gives one piles" with "sitting on a cold stone wall gives one piles"! Perhaps they just didn't like boys sitting down? Goes along with "don't share caps or you can catch dandruff". Martin of Sheffield (talk) 08:01, 20 February 2023 (UTC)

Reconciled with: prolonged sitting. Shantavira|^{feed me} 09:34, 20 February 2023 (UTC)

IMO Sexuality and superstitions is a good topic seems yet to be covered on WP Bookku (talk) 10:48, 20 February 2023 (UTC)

WP:WHAAOE: religion and sexuality. Tigraan^{Click here for my talk page ("private" contact)} 14:02, 20 February 2023 (UTC)

February 20

Recent Chinese UFO

Regarding this footage, did any reliable source offer a plausible explanation? Particularly, could it be a video manipulation and if not, what aircraft or natural phenomenon can produce such pattern? 212.180.235.46 (talk) 19:30, 20 February 2023 (UTC)

Looks to me like something pretty simple, such as countermeasure flares. Maybe the People's Liberation Army Air Force was doing some sort of training exercise over the area. As for what aircraft could produce such a pattern, basically any military aircraft could potentially do that, as long as it is fitted with flares. --OuroborosCobra (talk) 20:22, 20 February 2023 (UTC)

If it is a military aircraft throwing flares, as seems likely, its nearest base is at the dual-use military/civil Qiqihar Sanjiazi Airport. Philvoids (talk) 23:45, 20 February 2023 (UTC)

February 21

Thyroid pills

Not seeking medical advice. Question is inspired by just seeing a TV show involving someone with Hashimoto's disease. The person explained that this is an autoimmune disorder where the body attacks the thyroid gland, and this is bad because without a thyroid gland, you will die! But I know that thyroidectomy is a thing, and that the person usually has to thyroid pills for the rest of their life afterwards, but assuming they take their pills it's not that terrible in the scheme of things.

My question is what happens if the person doesn't take their pills, such as due to a supply interruption? Do they get symptoms if they miss one dose? What if they miss it for a week or a month? If they miss enough to become seriously ill, does the illness reverse once they are back on the drug? And is someone with Hashimoto's (assuming they are getting appropriate treatment) somehow in worse condition than someone who has had their thyroid removed outright?

My mom takes some prescription meds (not thyroid related) and regularly experiences hassles because the prescription has run out of refills (requiring new prescription requests to her doctor, which can take a while to get handled), and that sort of thing. In my mom's case, those occurrences have been annoying but not really dangerous. I'd like to think anyone with critical dependence on a drug should keep a very large supply on hand, but the dispensing system seems set up to prevent this. Thanks. 2601:648:8200:990:0:0:0:756C (talk) 00:52, 21 February 2023 (UTC)

See our article Hypothyroidism. Graeme Bartlett (talk) 00:55, 21 February 2023 (UTC)

Thanks, will look there. 2601:648:8200:990:0:0:0:756C (talk) 00:55, 21 February 2023 (UTC)

Goldfish size

I heard that goldfish keep growing throughout their life if you put them in a large enough take with the right conditions and food. Is this true? If so, why would they stop growing in other cases? 135.180.244.18 (talk) 05:28, 21 February 2023 (UTC)