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February 21

Technical term for the rejection of Cholecystokinin (CCK) stimulation by gallbladder?

You know how diabetics either have an auto-immune disorder in which the person's own immune cells attack the insulin-producing cells in the pancreas (Type I diabetes) or insulin-resistance (Type II) diabetes? I am wondering if there is a same concept for the gallbladder. I don't think it's so far-fetched to think that the gallbladder can actually refuse to recognize the CCK, sent from the intestinal cells. Is there a known disorder that has to do with the inability of the gallbladder to recognize CCK? How would that affect the liver's ability to channel the bile to the small intestine or its communication with the gallbladder? SSS (talk) 04:05, 21 February 2015 (UTC)

Wikipedia has a putative article titled Gallbladder disease, but it's pretty dreadfull. It is nothing even approaching a complete article on the subject. The article titled Gallbladder is more complete, but makes no mention of the disorder you note. --Jayron32 03:39, 21 February 2015 (UTC)

Wow. That was fast. Another question: I signed my name with four tildes, and a bot treated me as if I didn't sign my name at all. Could it be the nickname/name thing? SSS (talk) 04:05, 21 February 2015 (UTC)

It looks like you set up your signature preferences incorrectly. When you set up your own formatted signature (which it looks like you did) rather than the default signature, be sure your user talk page is linked from your sig. When you sign a post, the SineBot looks to see that your post contains a link to your User Talk page; if it doesn't it assumes you didn't sign. This page has some guidance for you in how to properly customize your signature. --Jayron32 03:49, 21 February 2015 (UTC)

A quick check of PubMed turned up [1], which says that cholecystokinin autoantibodies can be a result of autoimmune polyglandular syndrome type I. But the fault seems to be more at the autoimmunity level, with multiple hormones becoming neutralized. Still, it results in a decrease in the number of CCK-producing cells in the intestine. I'd expect some differences between this and diabetes since CCK is secreted to the lumen of the gut rather than remaining in circulation. There's also a reference [2] that hints at but in no way provides evidence for an autoimmune role in the decrease of CCK production in bulimia nervosa. Wnt (talk) 16:10, 21 February 2015 (UTC)

Oh, cool. Thanks. It may be interesting to wonder about whether other aspects of bulimia nervosa causes the decrease of CCK production or that the decrease of CCK production contributes to bulimia nervosa. SSS (talk) 16:42, 21 February 2015 (UTC)

Is the computer a logical robot?

Is the computer being a logical robot and what did the computer doing the logical robot?--83.237.202.23 (talk) 05:24, 21 February 2015 (UTC)

I'm not sure I understand the nature of your question. Understanding the epistemology and ontology of computers is a complex issue. The person best associated with these questions is perhaps Alan Turing, who not only looked at the nature of what a computer was, but also how computers and humans interact and what the nature of humanity was in relation to what computers can (and cannot) do. For example, a Turing machine and the concept of Turing completeness are commonly used to define a machine as a "computer", as distinct from devices which may perform calculations or do other tasks for us, but which are not defined as computers (such as, say, an abacus). A Turing machine is a hypothetical device designed to perform "thought experiments" about the nature of computers. Turing is also famous for his insights into artificial intelligence, devising the Turing test which is commonly used as another thought experiment to determine if some machine is truly "intelligent". If you're trying to understand the nature and philosophy of computers, Turing is your guy.--Jayron32 05:36, 21 February 2015 (UTC)

Another person who thought along these lines is the polymath John von Neumann, who like Turing also made important contributions to the early philosophy of "thinking machines" and "computing". He was working on a book titled The Computer and the Brain when he died; von Neumann's work in this area may also be useful for your research. --Jayron32 05:42, 21 February 2015 (UTC)

Much thanks! I understood so, that the calculator not be a logical robot, because the calculator being none logical, but the computer did being a logical robot, so in what was being the main sign of logical, if the main sign of logic was being intellect?--83.237.215.8 (talk) 08:23, 21 February 2015 (UTC)

Maybe a sequence of actions (of computing) was being the main sign of logical?--83.237.212.20 (talk) 10:07, 21 February 2015 (UTC)

So, whether being the sequence of (applied) linguistics is logical?--83.237.212.20 (talk) 10:24, 21 February 2015 (UTC)

Maybe a phonetics is being determines the logical of sequence of linguistics?--83.237.196.132 (talk) 11:59, 21 February 2015 (UTC)

I’m thinking that a (logical) phonetically sequence was being forming a linguistics.--85.141.236.114 (talk) 16:40, 21 February 2015 (UTC)

• Computers are logical in that they run computer programs using logical operators like "and" ""if" "not" then". Whether it is a robot depends on definition. Obviously a laptop cannot build a car in a factory, and if you ask someone to draw a robot, you'll probably see a metallic man like C3PO or the Tin Woodsman. But your laptop can play discs for you, and can be directed to direct the running of compatible household appliances, like lights and alarms and the lawn sprinkler. μηδείς (talk) 17:37, 21 February 2015 (UTC)

Robots are (at least, technically) just computers that are connected to motors and sensors so that they can make something 'physical' happen rather than just display stuff on screens or store things on disk drives. The term is getting gradually messed up by people who get confused about whether some radio controlled vehicles are "robots" (eg in "Robot Wars" where computers are rarely involved)...and in cases like drone aircraft where what happens is some kind of fusion between a robotic pilot handling the small details of the motion while some human "pilot" gives it higher level commands.

What distinguishes a "computer" from a calculator or some other piece of electronics is that computers are "programmable", you give them a list of commands and they go off and obey them all. Most people draw the line between computers and other electronic systems using the principle of equivalence to a "Turing Machine". A turing machine is an abstract description of a very, very basic computer - and it can be shown (according to the Church-Turing thesis) that all computers that are equivalent to a turing machine are basically the same thing (although the details of how they operate and the amount of speed and memory they have will obviously differ).

Things start to blur when you look at something like a cellphone - which has multiple computers inside of it (the main "CPU", many little graphics processors, probably others in the networking hardware and so forth). It has a bunch of sensors (radios, touch screen, battery voltage and temperature, tilt, acceleration, cameras...I'm sure there are others) - it's more than just a computer, but not quite yet what we'd describe as a robot.

Other devices, like an inkjet printer are (arguably) robots because they contain motors and can move things around in the real world. Some people would argue that since a printer can't drive around the room - it's not a robot - but that kind of definition gets difficult when you think about industrial robots that are bolted firmly to the floor too.

All of these terms have varied over time, and will doubtless continue to do so. The term "computer" originally meant "a human being who is paid to perform arithmetical calculations"...and our modern computers were originally "automatic computers" to distinguish them from people.

But these days, a computer is a part of a robot - like the motors, sensors and batteries. Just like a brain isn't a human being and a human being isn't a brain.

SteveBaker (talk) 23:55, 21 February 2015 (UTC)

Thank you! I believe that all programming languages are always been the same linguistics, as usual linguistics.--83.237.203.228 (talk) 11:35, 23 February 2015 (UTC)

We could been assume that the phonetic sounds (phonetics) are always combining (consolidating) all linguistic groups of languages into a single linguistically phonetically family.--83.237.203.228 (talk) 11:52, 23 February 2015 (UTC)

It remains to be seen, had be the robotization of the speech(-ing) apparatus of human, or at soon be of a primate?--83.237.244.173 (talk) 13:05, 23 February 2015 (UTC)

Perhaps in ancient times, the first humans phonetically was been imitated animals, because the first humans speech(-ing) apparatus was been undeveloped (primitive), so that’s humanity had been invented(-ing) a phonetic alphabet. That’s why, did been the robotization of the speech(-ing) apparatus of human, or at soon be of a primate?--85.141.236.167 (talk) 15:46, 23 February 2015 (UTC)

distance to Venus and Mars at the present time

Can someone easily tell me the approximate distance from the Earth to Venus and the Earth to Mars, in AUs, as of today? (Mars must be close to 2.5AU, I think.) Bubba73 ^{You talkin' to me?} 05:56, 21 February 2015 (UTC)

Venus: 1.422 AU, Mars: 2.201 AU. You can find out by typing "distance to venus" into Wolfram Alpha. --Bowlhover (talk) 06:26, 21 February 2015 (UTC)

Resolved

Thank you for both answering the question and telling me how I can find out such things. Bubba73 ^{You talkin' to me?} 06:30, 21 February 2015 (UTC)

As a slight aside, Wolfram|Alpha's Astronomical and History databases are very good. For example, it can tell you the distance between Mars and Venus when Issac Newton was born. -- LongHairedFop (talk) 10:28, 21 February 2015 (UTC)

Technical reports

I am currently writing a technical report for an investigation I am carrying out in 2 parts. I have written an introduction and procedure but my advisor told me that I shouldn't start writing the analysis until I have results from parts 1 and 2. I think I can still write an analysis for part 1 only so why would my advisor say this? Do any experienced scientists have any advice? 90.194.63.41 (talk) 11:51, 21 February 2015 (UTC)

Your advisor is correct unless you have external funding. Nimur (talk) 16:27, 21 February 2015 (UTC)

In terms of the wider point, I don't think people will be able to provide more detailed help without more explaination. For example, if these 2 parts are highly linked, and it is expected that results between them would be related and you're likely to write about this in your analysis, then there may be good reason why you advisor is recommending this. Even more so if what you write about could be strongly influenced by the result of than the other. Or even if this isn't the case, if for example the second part is more uncertain or speculative and may not have results that are particularly interesting or useful, it may be you will need more followups on the first part, or at least to write more, if you don't have much to say about the second part. (Or conversely it may if you do get good results for the second part, the first part suddenly gets a lot less important or interesting, and you'd only want to write a small bit about it.) There are bound to be other reasons why your advisor, may feel it's better to only write the analysis later, beyond providing more information here, have you considered asking your advisor for more information on why they recommend to do it that way? If it's not an environment where it will be acceptable to challenge the suggestion, if they are an "advisor" I would hope they would at least be willing to offer some more explaination, since it's clear you're not satisfied with what you[ve been told so far. Even if the explaination is still unsatisfactory, perhaps it will help you in providing information when seeking advice from others. 17:16, 21 February 2015 (UTC)

That makes sense. They are linked, yes. The first part of the investigation is verified by the second part and so from the results of the first part, we can predict what the second part should be. If the second set of results aren't as expected, an explanation would need to be hypothesised. What about the results? Do you think I should wait until I have results for both parts until I start writing that as well? 90.194.63.41 (talk) 17:22, 21 February 2015 (UTC)

The Sound of Meteors

What conditions would be necessary in order to hear a meteor falling? I mean in general. I know I'm not going to be able to get exact figures. Dismas|^(talk) 12:03, 21 February 2015 (UTC)

At what point in its descent? Most of them burn in the upper atmosphere, so they probably don't produce much noise. In contrast, there's the incident over Russia two or three years ago, and it produced an explosion. I don't recall reports of it making sound while flying through the air (except maybe the explosion). Maybe if you're close enough to hear it, you're toast anyway. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:17, 21 February 2015 (UTC)

Larger meteors will make more sound, and the closer you are the more likely you are to hear it. Huge meteors which explode, like the Tunguska event, can be heard over the long distances. Then there's the boom from those that survive to hit the ground or sea, making even more noise. StuRat (talk) 14:43, 21 February 2015 (UTC)

Don't forget also, meteors can create electrophonics. Anything near by the observer that acts like an half-wave dipole antenna may get stimulated by the low frequency radio waves generated by the plasmic trail and so produce an audio sound which can be quite evident to those on the ground – long before the sonic sound from the meteor reaches them.--Aspro (talk) 17:38, 21 February 2015 (UTC)

This phenomena was noticed before the the sands of of recorded history started to run but only recently been understood. First in Britain and a few decades later in the US. Just found this: [3].--Aspro (talk) 22:29, 21 February 2015 (UTC)

You seem to have developed a stutter. :-) StuRat (talk) 23:16, 21 February 2015 (UTC)

Freezer energy use as a function of mass and insulation

I need to know how much energy it takes to keep 5 kg and 30 kg of water frozen and cooled to -2 ± 1 °C in a 300 liter (50 cm x 50 cm x 120 cm) freezer in a 22 °C room as a function of the freezer's insulation in terms of its thermal conductivity. Assume the freezer's door is never opened, everything but the temperature differential is in a steady state, and the compressor starts at -1.0 °C and stops at -3.0 °C. I need a formula for this, or a reference with tables derived empirically.

There are literally dozens of otherwise reputable web sites which suggest storing more food in a freezer takes less energy than storing less. This is utterly false, but in order to prove this, I need the thermodynamics formula. I am not interested in anecdotes of any kind, especially of the "heat capacity of food" of which there are several utterly incorrect examples in the WP:RDS archives. I am only interested in a formula or reference which describes the energy input for maintaining the thermodynamics of the temperature differential across the freezer's insulation. 184.96.139.187 (talk) 22:31, 21 February 2015 (UTC)

Why does the OP 'need' to know this? Is this a homework question?--Aspro (talk) 22:40, 21 February 2015 (UTC)

Because so many people have gotten it completely wrong, here and everywhere else on the internet, and I feel a very strong moral obligation to explain to them exactly why in incontrovertible mathematical terms. It is not homework, but if it were up to me it would be homework for every thermodynamics student until most people start getting it right. 184.96.139.187 (talk) 22:53, 21 February 2015 (UTC)

I've never heard anyone say that it costs less energy to run a full freezer than an empty one, but I have heard a full freezer will maintain it's temperature longer when the power goes out. StuRat (talk) 23:22, 21 February 2015 (UTC)

The reason for the difference in cost is that when you open an empty freezer a lot more cooled air is lost, which the freezer need to recoolen. If the freezer is full, much less air is lost. μηδείς (talk) 23:52, 21 February 2015 (UTC)

How many times would you have to open the door and completely replace ~300 liters of cold air with room temperature air to match the amount of heat that leaks across the insulation in a single hour? Frankly, you are completely wrong. 184.96.139.187 (talk) 01:29, 22 February 2015 (UTC)

?!! The OP states “Assume the freezer's door is never opened” Water has a Specific Heat of about 2 at -10°C (kcal/kg°C). And it is H₂0. Therefore, it will be absorbing long wave infra- red radiation (which just passes through the foam polyurethane insulation like it isn't there) far more readily than pure “air”. Thus a freezer full of 'ice' without the door being open will use more energy. It is basic physics.--Aspro (talk) 00:24, 22 February 2015 (UTC)

Why do you say that foam isn't opaque to infrared radiation? That seems absurd to me. 184.96.139.187 (talk) 01:29, 22 February 2015 (UTC)

Said the opposite. Read it again.--Aspro (talk) 17:57, 22 February 2015 (UTC)

I read "long wave infra-red radiation (which just passes through the foam polyurethane insulation like it isn't there)" to mean insulation is ineffective against long wave IR. This was surprising to me, too. Is that what you meant to say ? StuRat (talk) 18:01, 22 February 2015 (UTC)

`Yes, that is what I meant. Had a quick google but could not find any long wave images in the public domain. Very long wave scanners are (as far as I know) are not even available to the military yet (they are a hassle and need cooling and a tech to keep them working) but a house become transparent at those wavelengths. One can see through the walls, central heating pipes, radiators, fridges and everything etc. That thermal radiation (which appear white, yellow, and red on the screens) is absorbed by food stuffs – more readily than bricks and mortar. Blue electromagnetic radiation has a lot more energy than red – but the red is continuous – night and day. The ground (terraferma ) even gives it off. It may only be a watt and a half per square meter per second but over 24 hours it all adds up. That is why cold stores to day are so large. Just doubling the surface area increases the volume 8 fold. Look in your modern fridge and is has expanded polyurethane foam. It main insulating property is poor convection and conductivity but longer (not short) infra red just passes through like it isn't there--Aspro (talk) 19:52, 22 February 2015 (UTC)

I think you meant doubling the linear dimension increases the volume by a factor of 8. Doubling the area increases volume by a factor of the square root of eight. Dbfirs 21:18, 22 February 2015 (UTC)

Yes, he made a grave mistake. :-) StuRat (talk) 00:05, 24 February 2015 (UTC)

Relevant is blackbody radiation. Every object which is not at absolute zero is always losing energy radiatively. The second law of thermodynamics is a mean bitch. --Jayron32 01:39, 22 February 2015 (UTC)

I agree with Medeis that a full freezer spills out less cold air than an empty one - which certainly suggests that the full freezer is more efficient. That's probably a marginal difference in the case of a 'chest' freezer where the higher density of the cold air causes it to tend to remain inside the chest rather than spilling out as it undoubtedly does with an upright freezer. Our freezer is a pull-out tray at the bottom of our refrigerator - and that's probably somewhere between the two in terms of partially-loaded efficiency. And of course, everything depends on how often you open the door, and for how long.

It's also true that when you initially fill the freezer, it's going to take more energy to cool down a full freezer than a largely empty one - the heat capacity of food is certainly going to be higher than air. So there are more unknowns there too.

But if you want a simplistic, quick answer, then I think the air-spilling-out-when-door-is-opened argument wins...and that's why it's so often quoted. But in the idealised world of spherical-cow physics, when the freezer is in steady-state and the door is never opened - it shouldn't matter how full it is.

The problem here is that our OP is asking for information about an idealized freezer (door never opened) in order to debunk all of the advice out there which is clearly discussing realistic freezers where the door gets opened a few times a day. These are NOT comparable situations.

SteveBaker (talk) 01:43, 22 February 2015 (UTC)

“when the freezer is in steady-state and the door is never opened - it shouldn't matter how full it is.”

The ability to absorb heat does matter. Dry cold air in a fridge does not absorb anything like that same amount of long wave infra red thermal radiation that food stuffs do That is why a cold store (with cold store workers going in and out all day long) full of (say) Dates require less energy to maintain that storage temperature than (say) candy. See:[4]. Cold dry air even less so, as it is mostly nitrogen and 21% oxygen. So on this point the OP is correct, in so much that what we are being told is nonsense. This, I think, is the point he is trying to get across. We are on the Ref Desk and so should be able to disassociate ourselves from repeating the 'full fridge' mantra and as the OP suggests we (and every thermodynamics student) should be able to get this right! This is why I thought is was a homework question. It takes energy to keep mass cool. More the mass the greater the need of cooling. As I said above... It is basic physics!--Aspro (talk) 18:32, 22 February 2015 (UTC)

As far as I can tell no one claims that a never-opened freezer is more efficient when full, so there's no point debunking that. What people do claim is that a frequently-opened freezer is more efficient when full. For example this .ca.gov page says "If your refrigerator is nearly empty, store water-filled containers inside. The mass of cold items will enable the refrigerator to recover more quickly after the door has been opened." -- BenRG (talk) 05:56, 23 February 2015 (UTC)

That is a perfect example of the total bullshit that pervades the internet discussions of the topic. You are trying to keep a mass colder than the ambient temperature. Unless the insulation is perfect, the larger the mass means that you have to spend more energy maintaining the temperature difference. 184.96.139.187 (talk) 01:13, 24 February 2015 (UTC)

For a closed freezer, the energy leakage via thermal conduction may be modeled by: $E = k {A \over l} \Delta T$ where k is the effective thermal conductivity of the freezer walls, A is the area of the walls, l is the thickness of those walls and ΔT is the temperature difference between the outside and the inside. At steady state, the energy loss is independent of the contents of the freezer. So as long as the freezer remains closed and there are no other mechanisms for energy transfer, the contents of the freezer don't matter. Achieving a constant internal temperature simply requires balancing the losses due to thermal conductivity. A full freezer has a much larger heat capacity than an empty freezer, so you will expend much more energy reaching that steady state, but the incremental effort to keep it there is the same regardless of the freezer contents. Of course if you are going to consider opening and closing the door, that is a whole different issue. Dragons flight (talk) 06:49, 24 February 2015 (UTC)

No! This I think is what the OP is trying to point out. Substances with low specific heat absorb less of the long wave thermal radiation than some other substances. So a completely empty freezer whose doors don't open requires less energy than a fridge that is full with anything – other than perhaps exotic stuff that is also as transparent as air . And I bet you wont find many fridges in your neighbourhood with those substances being stored. The manufactures repeating this mantra are - I think- attempting to say that be having a bit of cold mass already present enables them to claim that their fridge meets regulations (re: cooling capacity per 24 hours). That is nothing to do with energy consumption. Reminds me of that report on the radio some years back where a housewife had her house raided by the police. On hearing the mantra that one should not have a empty fridge, she placed large plastic bags of her lawn clippings into her chest freezer (in early summer, her lawn clipping where readily available in bulk). It was not the lest a bit funny to find out that a jobs-worth had overheard her telling a friend about this. So she got raided on a his tip-off as she was hiding a load of grass in her freezer. It was explained to her that this excuse was silly and she ought to plead guilty – (be amazed... this persisted until the lab report came in – on lawn clippings can you belive!) . So this full fridge mantra (as the OP is indicating) is total utter nonsense.--Aspro (talk) 19:01, 24 February 2015 (UTC)

Where are you getting the long-wave thermal? If it is internal to the freezer, then it makes no difference at all in the steady state condition (where the premise is you already have a uniform internal temperature). If you are talking about thermal radiation penetrating the closed freezer from outside, then I don't see that as being likely to be more than negligible. I don't see how long-wave thermal makes a difference to a closed, steady-state freezer. Dragons flight (talk) 19:56, 24 February 2015 (UTC)

February 22

Conjoined twins

In the article on Conjoined Twins, the author does not mention the first successful separation of craniopagus twins which occurred in Johannesburg, South Africa in early January (before 7 January) 1968 Shirley and Catherine O'Hare were separated and Shirley is still alive Catherine died at 10 months old from a heart complication. I would assume that as the twin that died did not die on the operating table or as a direct result of the operation that this would qualify as the first successful separation of craniopagus twins. Am I correct? <South African Medical Journal 27 April 1968 "Separation of Craniopagus Twins" pp. 412 - 424> <Advance News (Ogdensburg, NY) 7 January 1968 p. 18> <Saturday Star (Johannesburg, South Africa) 14 February and 21 February 2014> KJBrookes (talk) 08:47, 22 February 2015 (UTC)

That would depend on what the sources have to say about it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:17, 22 February 2015 (UTC)

It would be better to discuss this on the Talk page of the article itself rather than here. SteveBaker (talk) 15:36, 22 February 2015 (UTC)

Citation for Yang-Mills Theory - Mathematical Overview

Hi, I'm currently conducting a research review as part of my undergrad degree on classical gauge theories. All the books and articles I've found have assumed the fact quoted in the article (https://en.wikipedia.org/wiki/Yang%E2%80%93Mills_theory#Mathematical_overview) that "the transition between "upper" ("contravariant") and "lower" ("covariant") vector or tensor components is trivial for a indices" but none of the primary sources I've found explicitly state it and the fact is provided in the article without citation.

As far as I can tell, user Pra1998 added it back in 2009 but it's never had any citation and I was wondering if anyone (i.e. Pra1998) could point me in the direction of a citation. — Tjlr2 (talk) 18:57, 22 February 2015 (UTC

Pra1998 has provided an answer elsewhere — Tjlr2 (talk) 19:09, 22 February 2015 (UTC)

Animal species with biological ornaments in females

Are there good sources about animal females (vertebrates and/or invertebrates) who have more or less elaborate biological ornaments to attract and claim males for mating (given the stated rarity in biological_ornament#Female_ornamentation)? Brandmeister^talk 18:56, 22 February 2015 (UTC)

Females will show receptivity to mating by displaying and chimps in estrus have red rumps.soure I am not sure if this counts as ornamentation, though. μηδείς (talk) 01:15, 23 February 2015 (UTC)

A websearch for "drab male, ornate female" sans quotes showed that the three phalaropes have brightly coloured females, and the males are duller. The females also fight over mating rights, and males do most of the incubation and chick care. I suspect there are other species that are similar (seahourse males also look after the fry, but there is no sexual dimorphism). LongHairedFop (talk) 09:38, 23 February 2015 (UTC)

Homo sapiens have the 'drab male'/'ornate female' thing going on, but that's not biological ornamentation. Ornamentation that the female of the species adopts comes typically comes from brightly colored items acquired from the environment. SteveBaker (talk) 15:17, 23 February 2015 (UTC)

I'm pretty sure human female breasts count as a biological ornament through a secondary sex characteristic. Though of course there's lots of cultural stuff too that is not so biological. SemanticMantis (talk) 15:41, 23 February 2015 (UTC)

Fair enough :) Brandmeister^talk 22:22, 23 February 2015 (UTC)

We have tons of relevant articles, some of them have examples: sexual selection, sexual dimorphism, biological ornament, mate choice, Fisherian runaway, secondary sex characteristic.

The refs in this article [5] should be very relevant. Here's a paper specifically on female ornamentation in the rock sparrow [6]. I think /female ornamentation/ on google scholar [7] will be a good search to peruse. You will get lots of theory hits, but also examples sprinkled in. Check out the interesting example of conditional female ornamentation in starlings here [8]. Here's a pop-sci NYT write up that mentions a few sources and examples, e.g. the female pipefish.

Evolutionarily speaking, the general understanding is that the selection processes make male ornamentation more likely, as males don't have to invest as much (typically) in reproduction. And that asymmetry in reproductive investment goes back to evolution of anisogamy, itself a subtle and not-completely-understood process. SemanticMantis (talk) 15:41, 23 February 2015 (UTC)

Does higher levels of Testosterone help in recovering lost/damaged tissue, same way it helps increase recovery and growth of muscles etc.?

High levels of testosterone, of course, will enhance physical performance, physical recovery and muscle growth etc... This is known.

But will it have any direct effect on improving and accelerating the rebuilding of lost/damaged tissue??? Lost/damaged tissue should, in theory, recover and rebuild during sleep and rest, while physical exercise will obviously also contribute to that.

But my question is simply, as I have already asked, will testosterone-treatment have a direct positive effect on healing/rebuilding damaged/lost tissue??

2A02:FE0:C711:5C41:65AF:208C:ACFF:471A (talk) 19:03, 22 February 2015 (UTC)

I am by no means an expert on this, but for what it's worth, my dad was prescribed steroids when his hearing in one ear deteriorated, and his hearing in that ear recovered. Of course, If you're planning on taking some sort of medication, you'd better talk to your doctor first. Also, be aware that Wikipedia does not purport to provide medical advice. — SamX‧☎‧✎‧S 22:43, 22 February 2015 (UTC)

I would never take such treatment unattended, nor would I motivate others to do so. There are serious risks and potential downsides involved, at least if one abuses it. I'm simply trying to understand Testosterone's full effect and purpose, and I have not found info regarding how/if it affects regrowth in tissue, even though my instincts tell me it probably must. So I am not asking for medical advice - I am asking for knowledge/enlightenment. Hopefully I can still get that. Thanks. 2A02:FE0:C711:5C41:5C36:E937:98DB:17CA (talk) 09:04, 23 February 2015 (UTC)

• Most of the scientific evidence indicates that testosterone actually has a negative effect on wound healing. See http://www.medscape.com/viewarticle/524313_5 for details. Looie496 (talk) 15:30, 23 February 2015 (UTC)

GR inertial reference frames.

This may be a stupid question. As I understand it in General Relativity the laws of physics hold true for all inertial reference frames. What about non-inertial reference frames? Can you take any arbitrary point declare that it is rotating and apply the the laws of physics just as well as at any other point? I ask because I'm in discussion with a geocentrist and the stuff they are saying is clearly wrong but I'm no physicist. — Preceding unsigned comment added by AHuntersMoon (talk • contribs) 19:43, 22 February 2015 (UTC)

In General Relativity the laws of physics hold true for an arbitrary reference frame. All reference frames are absolutely equal. Ruslik_Zero 20:58, 22 February 2015 (UTC)

This is really at a lower level than relativity, but "Yes" is the answer to your question - the laws of physics are applicable everywhere. The essential point is that an observer in a non-interial (accelerated) reference frame can detect that fact by measuring the acceleration. We can do that now by dropping something (see Isaac Newton#Apple incident) and using Foucault's pendulum or a gyroscope or a bathtub to measure the Coriolis effect. All of which are quite valid under Newtonian mechanics without relativity becoming involved. Tevildo (talk) 21:23, 22 February 2015 (UTC)

You're having a serious discussion with a geocentrist? Did you make a typo, or are you really trying to debate someone who thinks the whole universe revolves around the Earth? --Bowlhover (talk) 02:02, 23 February 2015 (UTC)

The equivelance of all frames in GR means that it is quite utterly meaningless to ascribe any point as being the center. Everything rotates about everything else, and if this geocentrist wishes to treat the center of the earth as the center of the universe, then that's a perfectly valid point to choose. Of course, picking the center of the milky way galaxy might make some calculations easier...but then choosing the driver's seat of his/her car would make a better choice for other calculations. It's all a matter of choosing an appropriate coordinate system for the task at hand. If you wish to avoid getting a speeding ticket, then choosing your car isn't going to help you when plead that your vehicle was stationary rather than doing 90mph in a 55 limit. On the other hand, if the judge chooses a heliocentric viewpoint then you're going to jail for driving at 30 kilometers per second. On the other hand, if you ask your passenger to hand you a mint from the glovebox, you'd prefer that he not try to figure out where to grab it from using a coordinate system based on the large continent on Kepler-22b.

Incidentally, if your opponent in such a debate is truly in need of a sound logical spanking, they are probably drawing poor conclusions from their core belief. I recommend asking how it can be that we have rovers driving around on the surface of Mars and how, from the rover's point of view, it would appear that Mars is the center of the universe. Sadly, such people are apt to deny the existence of Mars rovers, manned moon landings, safe measles vaccines, the holocaust and so forth.

If you really want to meet some people who are REALLY good at spinning a story around scientific improbability, just get chatting to some of the few remaining core members of the flat earth society. Their arguments are oddly compelling!

Good luck! SteveBaker (talk) 04:51, 23 February 2015 (UTC)

The origin of a coordinate system and the center of a physical system are different things. When people say that sun is at the center of the solar system they don't mean that the origin of coordinates should be there. They mean that the sun is at (or near) the barycenter of the solar system. It's a geometric property that has nothing to do with coordinate systems or any other arbitrary unphysical choice. In general relativity, spacetime has a definite geometry. You're not free to imagine that it has some other geometry. -- BenRG (talk) 08:41, 23 February 2015 (UTC)

February 23

brightness of an inferior planet

Suppose you have in inferior planet like Venus. Assume that the planet orbits are circular and in the same plane. What is the equation of the apparent brightness of the inner planet as a function of where it is in its orbit? (When it is more than 1 AU away, more of it is lit but it is farther away, etc.) Bubba73 ^{You talkin' to me?} 02:12, 23 February 2015 (UTC)

Well, there's one formula for how brightness reduces with distance, another for what phase the body is in relative to Earth, and then the average insolation angle must also be considered. That is, is the sunlight reflected towards Earth from sun rays that hit the planet straight on, and are thus bright, or at a shallow angle, and are thus dim ? I suppose the average reflectivity of the place on the planet reflecting light towards Earth should also be considered, if it's not uniform for the planet. Mars has more reflective polar caps, but neither Mercury nor Venus do. StuRat (talk) 06:15, 23 February 2015 (UTC)

And assume that the planet is uniform. Bubba73 ^{You talkin' to me?} 08:24, 23 February 2015 (UTC)

I am really curious. What makes a planet inferior? That is a term I have never heard of when referring to a planet. 175.45.116.60 (talk) 22:29, 23 February 2015 (UTC)

I think every planet is inferior to the Earth. :-) But astronomically it means that it orbits closer to the sun/star. In our case, Venus and Mercury are inferior planets, see Inferior and superior planets. Bubba73 ^{You talkin' to me?} 00:35, 24 February 2015 (UTC)

• What will matter is the cross section of the plant visible, the planet's albedo, its distance from the sun (how much light is hitting it--which you are assuming is a constant, given a circular orbit) and how far from the earth it is (how much of that light is getting here. The lessening of the brightness will differ by the square of the distance. For an exact mathematically written formula you could pose this at the math desk. μηδείς (talk) 22:39, 23 February 2015 (UTC)

The actual albedo doesn't matter since it is assumed to be constant. Years ago I thought about working this out, but never got around to it. Maybe someone knows the answer to a simplier version - when is the inferior planet the brightest? Bubba73 ^{You talkin' to me?} 00:35, 24 February 2015 (UTC)

Well, yes, the albedo's constant, but two planets at the same distance will have different relative brightnesses as seen from earth if they have different albedos. In any case, I suggest you ask at the Math Desk, as someone will very quickly come up with an actual equation for your specified parameters.

(For example, I had an argument once over whether it made sense to run between shelters in a rainstorm. I argued that all other things being equal, the less time spent in the rain, the less wet you will get. But then we considered the effects of angle of attack. If you have a glass plate 1 meter square of negligible thickness (approximating an ideal windshield) and the plate is held horizontally and moves at a slow speed it ill get much wetter on the surface than a vertically held plate.

Paradoxically, if the plate is moving at the speed of light between shelters, it will get wetter when held vertically, because it will "scoop up" all the drops in front of it, whereas if held horizontally, it will get between shelters before many, if any drops can manage to fall on it. I posted that scenario at the Math Desk and quickly got a response that gave an answer for accumulated wetness depending on angle, speed and volume of rain per cubic meter and the angle and speed of the windshield.) μηδείς (talk) 18:27, 24 February 2015 (UTC)

Oh, an as to when the planet will appear brightest in the simplified question is a minimax equation that will be a function of the relative angle to the sun. As the planet gets closer to the earth it will shrink in appearance from a crescent to only showing the dark side when the angular difference is zero. As the angular distance increases, the amount of reflective face visibe t the earth will increase, but the brightness that reaches the earth will lessen in proportion to the square of the increasing distance. I don't know myself how to calculate the area of the visible crescent, so for the exact formula, again the Math Desk will be of help. μηδείς (talk) 18:35, 24 February 2015 (UTC)

Well, I found equations for the actual brightness of the planets in Astronomical Algorithms, by Jean Meeus, chapter 41. Bubba73 ^{You talkin' to me?} 19:15, 24 February 2015 (UTC)

OK, then let's mark this Q resolved. StuRat (talk) 19:23, 24 February 2015 (UTC)

Resolved

Did the speed of light been a constant in nature?

The speed of light is been a constant only in the inertial closed physico-mathematical systems in which the observer and the light source are moved simultaneously, is it been so? I’m thinking that the speed of light in nature had an initial speed and final speed, is I’m right?--83.237.203.228 (talk) 11:27, 23 February 2015 (UTC)

Read the article speed of light if this topic interests you. --Jayron32 12:08, 23 February 2015 (UTC)

Thanks! I’m assume that the speed of light is been a constant only in the case where the light source to constantly been in front of the observer.--83.237.244.173 (talk) 13:18, 23 February 2015 (UTC)

Someone asked a similar question a while ago. It seems to depend on whether the light spectrum is an idea of optical or magnetic. I haven't seen that guy around in a while, but if you find him, he may be able to elaborate. InedibleHulk (talk) 13:31, February 23, 2015 (UTC)

In anyway cases, problems with the speed of light is always been solving in aggregate systems.--83.237.244.173 (talk) 13:36, 23 February 2015 (UTC)

Like the gravel industry? Yes, asphalt can create some breathtakingly inferior mirages. Turns heat to water, at least as far as our optical systems are concerned. No electrical resistance, though. InedibleHulk (talk) 13:50, February 23, 2015 (UTC)

I'm talking about the fact that the study of the light is always been conducted in aggregate (totally) systems, that's why we been interested in aggregate (totally) sloving these problems.--83.237.244.154 (talk) 14:29, 23 February 2015 (UTC)

The aggregate (totality) of tasks is always been determines the solution of the problem.--85.141.236.167 (talk) 15:55, 23 February 2015 (UTC)

I have a bit of trouble parsing all of the question, but the speed of light in a vacuum (the thing we usually mean by "speed of light" and the thing thing that is constant for each observer) is constant for all observers, at least according to special relativity, which has been, to a very high degree, verified in nature. This includes unintuitive results such that two observers, one at rest with respect to a light source, and one approaching it at 1/2c in the frame of reference of the first observer will both measure the speed of a photon from that light source as the same constant c. --Stephan Schulz (talk) 16:21, 23 February 2015 (UTC)

If you watching the speed of light in different inertial systems, it will never been a constant, that's what I'm talking about.--83.237.242.202 (talk) 16:41, 23 February 2015 (UTC)

No, if you are watching the speed of light in different inertial systems, it will ALWAYS be a constant. That's the basis for the various Einsteinian theories of relativity. --Jayron32 17:56, 23 February 2015 (UTC)

As I know, Albert Einstein solved the problem of relativistic quantum mechanics in the form of the closed inertial system which represents an aggregate (totality) of inertial systems. That’s why I think that Albert Einstein is been right in his particular case of physics which was been occupy whole physics.--83.237.215.99 (talk) 18:51, 23 February 2015 (UTC)

There is been optics which based on the Laws of mechanics of the Isaac Newton, so why could exist the relativistic quantum mechanics which been based on the Laws of mechanics of the Isaac Newton?--85.141.236.229 (talk) 21:07, 23 February 2015 (UTC)

By definition, optics involves light traveling through matter. That is, something not a vacuum. The speed of light in a vacuum is the universal constant. Light slows down when it travels through matter. --Jayron32 21:12, 23 February 2015 (UTC)

I’m thinking so, the optical medium is been a closed inertial system in which there is been an observer, and also to the same state of vacuums including the state of inert sparse vacuums are been unstable, so that the vacuum state is not been the ideal physical environment.--85.141.239.130 (talk) 21:35, 23 February 2015 (UTC)

Everyone of those words is an English word, and yet that is completely nonsensical. Perhaps you'd have more success finding an "ask a question" website in your native language. It is hard for us to help correct your misconceptions when we can't tell your misconceptions from your impenetrably bad syntax. --Jayron32 00:53, 24 February 2015 (UTC)

Thank you! It is pity, but I was banned in the Russian version of Wiki. What from your point of view are being an optical mediums, it is a mediums which containing a light in self, or mediums which refract a light?--85.141.239.139 (talk) 01:18, 24 February 2015 (UTC)

What be if we assumed that in nature the optical mediums are always been conductive environments, but not been dielectric environments?--85.141.239.5 (talk) 02:41, 24 February 2015 (UTC)

As far as I know even Albert Einstein told that the cases of quantum mechanics been fully applied to the cases of conventional mechanics (mechanical movements of Isaac Newton), but I argue that this situation is been vice versa, that’s is been, the cases of conventional mechanics (mechanical movements of Isaac Newton) been generalized and complemented the cases of quantum mechanics.--83.237.242.202 (talk) 17:03, 23 February 2015 (UTC)

From my point of vision, it is been natural, that quantum mechanics is been a part of conventional mechanics (mechanical movements of Isaac Newton)!--83.237.242.202 (talk) 17:29, 23 February 2015 (UTC)

Can I recommend (again) that you seek the advice of the Language Desk on the proper use of the various parts of the verb 'to be'? It would make your posts here a lot more comprehensible. AlexTiefling (talk) 22:11, 23 February 2015 (UTC)

A Really Tall Ship, or how to "fly" a planet.

This is a question about flying an Earth-sized planet like a spacecraft.

The rules would be,

• A roughly Earth-sized planet, not a gas giant. The latter would have lots of hydrogen and helium, which would make nuclear fusion more feasible than on Earth. However, if that's easier, an existing planet like Mars could be chosen, or even a plausible planet that doesn't exist (say, one halfway between Earth and Mars).
• There should be mainly today's technologies, including everything we know but don't have in that quantity. Far future technology is forbidden; for example, with Honorverse technology and its near-magical gravity projection, flying a planet would be much easier, not to mention with Treknology.
• Large-scale application is allowed and even encouraged. The planet might have an enormous number of fission plants for propulsion; however, the fuel needed must be plausible.
• Efficiency figures can be estimated with some optimism; I'm not trying to fly away with Mars or anything based on replies on the internet. :)

The thoughts I came up with:

• A "free" planet (not in the Lensman sense, just a planet that doesn't orbit a star) doesn't need a lot of acceleration; whenever it approaches a star, its inhabitants would see that for millions of years in advance, even with today's telescopes. That would, even if they were on a collision course with a star, open a very long time window to avoid that star. One millimeter per second is about 31km per year, or 1AU in 5000,000 years, so that tiny course correction would add up to a successful evasive maneuver. The disadvantage of the free planet is that it doesn't have access to cheap fusion, i.e. a star.
• A free planet would also be much colder than Earth, and thus still have more hydrogen / helium in its atmosphere.
• A "bound" planet like Earth could possibly use the solar wind to its advantage and slowly spiral in or out. Out being the way to go to counter solar expansion, but would it be fast enough? What I'm thinking of is a magnetic "sail" , a shaped magnetic field which deflects more particles to the direction from where the planet came than where the planet is going, and thus providing net momentum change. That would add to orbital velocity and cause the planet to spiral away from the star.

My question is if there are estimates, or maybe even scenarios on these cases, and if there are acceleration and/or delta v figures for bodies which fit my criteria. Or maybe some fatal flaws which would make my ideas fall flat.

Thanks in advance. 217.255.147.211 (talk) 15:47, 23 February 2015 (UTC)

For a planet without an atmosphere (including where the would-be atmosphere is frozen or liquid), I like the idea of coilguns, pointing up from the surface. You could mine the planet for iron, accelerate it to the speed of light, and fire it in whichever direction you want to flee from. You'd have one main (fixed) coilgun, and smaller ones, which could be tilted, for maneuvering. Nuclear fusion would be a good power source. StuRat (talk) 16:05, 23 February 2015 (UTC)

You. Compressed. Oedipus.

I didn't want any treknology or "accelerate it to the speed of light" magitech. See item #2 217.255.137.5 (talk) 08:08, 24 February 2015 (UTC) (OP)

That's not the way to comment on a reply even if it's off. StuRat probably meant "relativistic velocity". And he was talking about accelerating the iron to that kind of velocity, not the planet itself. Still a bit energy-intensive, though. - ¡Ouch! (^{hurt me} / _{more pain}) 09:27, 24 February 2015 (UTC)

Correct on all counts. OP, if you continue to behave like that, we may delete your Q and ban you from asking any more. StuRat (talk) 19:27, 24 February 2015 (UTC)

With enough guns, they need not even swivel. Most of the time, I imagine, "fire whenever the target acceleration vector is below your horizon" is enough control. —Tamfang (talk) 20:24, 24 February 2015 (UTC)

If none of the guns were tilted, then each would push the planet along a different vector, but none would rotate it so that the main gun could be used. You could have multiple guns with different tilt angles, as opposed to a smaller number (even just one) that swivel, but that would mean the vectors wouldn't be perfect, so you would waste some energy and matter that way. However, if making guns that can swivel is problematic, that might be the preferable solution. StuRat (talk) 20:31, 24 February 2015 (UTC)

You might find some fun stuff at this TV tropes page [9]. Lots of refs to sci-fi media, many of which at least wave their hands at the physics. SemanticMantis (talk) 17:45, 23 February 2015 (UTC)

I was thinking myself about Unicron. --Jayron32 17:54, 23 February 2015 (UTC)

These are fun. However, most depictions are just "bigger is cooler" stuff. In one old Japanese movie (1950s or early 1960s, and it's not listed at Planet Spaceship#Film), they used some huge chem-thrusters to move Earth, within months. 217.255.137.5 (talk) 08:08, 24 February 2015 (UTC) (OP)

• Alright, Earth gives you the problem figure: 5.97219×10²⁴ kg = 3.0×10-6 solar mass (The latter is actually pretty amazingly high, when I think about it). To move that course, say, a km in a million years means an average transverse velocity of 1 mm/year (plate tectonics manages speeds this high, but only for thin little bits of crust, not the whole planet). That's an acceleration of ( 2 mm/year )/10^6 years (the 2 comes in because it only has top speed at the end...) So we need a force F = m a of 6 x 10²⁴ kg * 2 x 10^-6 mm/yr² = 1.2 x 10¹⁹ kg mm/yr². Now substitute 1 mm = 10^-3 m and 1 yr = (365.25)(24)(60)(60) s and we get ... 12 kg m / s^2 ?!. Hmmm, that's pretty remarkable. We're talking about, like, 1.2 kg of weight tugging on the planet continuously for a million years. Either I fouled up or this is more doable than I thought. Still, we have to bear in mind that to avoid a star you can't just move the planet by one km, but by some significant proportion of an astronomical unit, i.e. millions of kilometers. I think I'll pause and wait to be found out for an idiot before going on. Wnt (talk) 18:00, 23 February 2015 (UTC)

No it is quite practical, see [10] for instance. It won't turn the earth into a nippy Star Trek type spaceship but it could be used to for instance move the earth out to a safe distance as the sun gets hotter near the end of its life. Dmcq (talk) 21:08, 23 February 2015 (UTC)

IIRC, Master of Orion was the first computer game to feature a planet-sized starship. It was called "The Guardian". Coincidence? - ¡Ouch! (^{hurt me} / _{more pain}) 09:27, 24 February 2015 (UTC)

I was looking at a different approach: install some fission plants, power some big, probably city-sized ion thrusters and fire them when they are pointing the right way. This only assumes that the planet rotates at all, and doesn't have an atmosphere. For north/south maneuverability, one would need half a dozen thrusters and good timing. At the exhaust velocity of ion thrusters, vaporising the iron, or whatever, is only a minor power/efficiency issue before accelerating.

However, that "let a comet pull Earth forward a bit, and recharge it by letting Jupiter pull it" idea sketched in The Guardian looks really elegant. 217.255.137.5 (talk) 08:08, 24 February 2015 (UTC) (OP)

(H:EC)Earth is about 6*10²⁴kg, so we need about 6*10²¹kg m/s of momentum to get that 1mm/s velocity change.

It's well known that you need less reaction mass if you throw it out faster; OTOH, we're on a limited energy budget (again), and throwing it faster will use much more energy (4 times for doubled velocity).

OTOH^2, if we don't achieve escape velocity, which is about 11km/s, we won't change Earth's momentum, because the ejecta will return. It'd be a closed system.

The details are complicated, but an exhaust v which slightly exceeds escape v will result in a momentum change which depends strongly on how slightly we exceed escape v. I'll use 16.8km/s (1.5 times Earth's escape v ) from now on, which will result in about 12.6km/s "final" velocity.

So, we need to eject about 4.8*10¹⁷kg to get the desired delta v of 1mm/s.

Putting these together, we get m/2 v² = (2.4*10¹⁷) (2.8*10⁸)kg (m/s)² = 6.7*10²⁵ J.

One Joule is one watt-second, so 3.1*10⁷Ws are a watt-year, and 3.1*10²²Ws are a million gigawatt-years. If we could run 2200 gigawatt plants for one million years, we could eject all the matter necessary for 1mm/s.

With a bit of luck, we would invent a fusion plant before our fission fuel runs out. (With today's technology, we only have two sources of power: fusion and fission. Everything except fission fuel is ultimately solar fusion energy if you go all the way back. And solar fusion wouldn't be available on a rogue planet (that's what you called a "free" planet). I assume you don't want me to invent things as exotic as a p-brane tap, which would provide essentially unlimited energy.)

For a rogue planet, any encounter with a star is an opportunity; the closer you get, the more it will deflect your course. If you get close enough, you can use an early course adjustment in the range of mm/s to get a deflection in the km/s range.

"All I ask is a tall ship, and a star to swing her by." - ¡Ouch! (^{hurt me} / _{more pain}) 09:27, 24 February 2015 (UTC) BTW, I like that word. "Treknology".

Fun though this is, the Reference Desk isn't really here to engage in speculation. This question would be better asked of Randall Munroe in the "What If" section of his xkcd comic strip. RomanSpa (talk) 09:05, 24 February 2015 (UTC)

I suppose this is a valid RD question. For one, the IP didn't ask for speculation, nor "But what if we tried more power?" - ¡Ouch! (^{hurt me} / _{more pain}) 09:33, 24 February 2015 (UTC)

I think it's possible to defeat the OP's suggestion of using a thruster that is timed to fire only when the planet rotates into the right position, but alas, my physics-fu feels weak today. I'm thinking that there's no obvious drawback to realigning the rotation of a rogue planet however is convenient; and of course what's convenient is to have one pole facing in the direction you intend to thrust so that you can fire your thruster 24/7. (If you're using thrusters that is) Problem: how much energy does it take to realign a planet's axis? Well... I'm thinking it's not energy, but angular momentum... in theory, you ought to need very little energy I think, provided you're able to throw off enough sheer mass of propellant (because KE = 1/2 mv^2, but momentum is just mv, in this case multiplied by the torque arm) But what the practical minimum is, assuming some grand space elevator, balancing KE vs. lifting energy vs. escape velocity... that I don't know. It's also worth noting that angular momentum changes can sometimes be put on a planet from a fairly long range, as with the precession of the Earth's axis, and I don't know how clever and creative you can be with that. I'm thinking a better answerer could come up with a calculation to put those timed rocket firings right out of your mind, but that's just a guess. Wnt (talk) 23:01, 24 February 2015 (UTC)

The problems with using a thruster only when the planet rotates into the right position:

1) The thruster will only move in a circular pattern (well, precession of the equinoxes may eventually move it in a broader band, but that would take thousands of years). There's no guarantee that the direction they want will lie on that circle.

2) Obviously, you'd only be able to use the thruster a small portion of the time. This means either you would accelerate much slower, or you would need a far bigger thruster.

3) Turning the thruster on and off might create annoying tremors around the site, and eventually cause structures to crack and fail. (Presumably any thruster would need to be turned on and off periodically for maintenance, but hopefully not once a day.) StuRat (talk) 23:11, 24 February 2015 (UTC)

Referencing

Am I right in thinking that when writing reports its not necessarily to reference anything that's common knowledge in that industry. So for example saying that using a clean room for any scientific experiment would reduce contamination is generally common knowledge as is using a certain type of microscope to look for certain things etc. 194.66.246.16 (talk) 19:33, 23 February 2015 (UTC)

They could still be specific. For a clean room, they could specify exactly how clean, like "removes 99.999% of all particulates above a size of ...". StuRat (talk) 19:48, 23 February 2015 (UTC)

If the report was concerning clean rooms, they would probably be aware that cleanliness is categorised using standard methods.--Phil Holmes (talk) 14:06, 24 February 2015 (UTC)

Unless the experimenters directly checked this, they would probably just name the equipment, e.g. laminar flow hood. But I don't think that's often specified in tissue culture papers. Someone might use a lab manual reference for the kaboodle, i.e. "routine cell passaging and harvest was done per [1]" where 1 is Maniatis or something, whatever your lab prefers, and that book might have a section on recommended sterile procedure. Wnt (talk) 20:51, 23 February 2015 (UTC)

In a somewhat different context, cleanliness might be implied when specific guidelines are quoted, e.g. Association for Assessment and Accreditation of Laboratory Animal Care International. Wnt (talk) 21:01, 23 February 2015 (UTC)

Over citing rarely hurts anything, while under citing because of supposed "common knowledge" can lead to misunderstandings, possibly even accidents. You may wish to read Wikipedia:You_do_need_to_cite_that_the_sky_is_blue. SemanticMantis (talk) 20:13, 23 February 2015 (UTC)

The issue, as always, is common knowledge to whom? Wikipedia should be written for people who know nothing about the subject they are reading about. It should not consider common knowledge those things which are commonly known only among experts in the field. There's a difference between citing something like "the sky is blue" which depends only on basic human experience, and citing something which requires at least some background in the field of study. One may not always need to cite the former; the latter should ALWAYS be cited. --Jayron32 21:09, 23 February 2015 (UTC)

See also WP:POPE - do you really know what everyone who reads your report already knows and doesn't know? SemanticMantis (talk) 20:19, 23 February 2015 (UTC)

The PhD dissertations I've looked at have run to dozens or hundreds of pages to cover the same material that a couple page journal article would because of the need to reference and explain every little detail. Rmhermen (talk) 20:57, 23 February 2015 (UTC)

Sure, in a dissertation, 10 or 15 papers might be cited each covering a small point. In a journal article, the material might get one cite: (reviewed by Xu et al., 2013). But that's all the domain of academics. Context is important but "reports" for an "industry" doesn't give us much to go on. I'd hope that reports in the nuclear engineering industry are more heavily cited than reports in the fashion industry... SemanticMantis (talk) 21:16, 23 February 2015 (UTC)

Title lineage of University Physics

For the textbook University Physics by Sears, Zemansky, and Young, which the referenced article says is in its 13th edition, is the title "College Physics, 7th Edition" (of which I have a copy with those authors listed) with ISBN 0-201-17285-2, one of the editions, or was/is there a separate title line in which all editions are entitled "College Physics"? 20.137.2.50 (talk) 20:08, 23 February 2015 (UTC)

I think it must be the same - Bookfinder doesn't seem to list an edition of University Physics earlier than the 10th edition. Bubba73 ^{You talkin' to me?} 01:13, 24 February 2015 (UTC)

They're different series. (Confusing, though.) See for example the 3rd editions of College Physics [11] and University Physics [12]. I believe, although I don't have them handy to check, that the secret code is "college"=algebra and "university"=calculus. --Amble (talk) 01:32, 24 February 2015 (UTC)

Oh yes, should have looked at reference #3. Bubba73 ^{You talkin' to me?} 01:52, 24 February 2015 (UTC)

And Hugh D. Young: "Young also wrote an algebra-based version named Sears and Zemansky's College Physics, which is currently in its 9th edition." Bubba73 ^{You talkin' to me?} 01:56, 24 February 2015 (UTC)

If beer and wine are acidic, then why do they taste bitter?

Why might have caused the bitter taste? Could it be a chemical compound, or could it be the taster's genes? 66.213.29.17 (talk) 22:14, 23 February 2015 (UTC)

• Alcohol itself is considered to be one of the tastes. Beer can be bitter because it has a quantity of roasted malt byproducts, and wine picks up some of its quality from the barrels it is aged in. μηδείς (talk) 22:32, 23 February 2015 (UTC)

Hops are used to give a bitter taste to beer - the details are explained here. Apparently the hops contribute a variety of acids that taste bitter. Mikenorton (talk) 22:40, 23 February 2015 (UTC)

I am not at all sure that is correct. Hops are the closest relative there is to the cognate hemp (Cannabis). I suspect the original reason was for effect, not a biter taste. μηδείς (talk) 05:34, 24 February 2015 (UTC)

Even the most casual reading of our own hops article shows your idea is nothing but nonsense. 131.251.254.154 (talk) 17:35, 24 February 2015 (UTC)

The acidity gives rise to the sourness of beer and wine. As Mike says, the bitterness of beer comes mainly from hops, a bitter-tasting herb. The bitterness of wine comes mainly from tannins in the grape skins, and, for wine that is aged in barrels, from tannins in the oak. Looie496 (talk) 22:53, 23 February 2015 (UTC)

Simple, inexpensive white wines fermented in stainless steel will lack tannins, and will be about as sour and about as acidic as diluted lemon juice. Cullen³²⁸ Let's discuss it 22:58, 23 February 2015 (UTC)

The link claims that the bitter-tasting chemicals in hops are acids, specifically alpha acids, and our article seems to agree. I don't understand, though, how are these molecules acids? Where do the protons come from? If it's from the hydroxyl groups, why aren't they just as likely to split off an OH- as an H+ ?

Take a look at Vinylogy, which may help a bit. Mikenorton (talk) 23:17, 23 February 2015 (UTC)

Enol might be the better article, it's a bit easier to understand and the concept is the same. In any case, it's the alpha-carbon that loses the proton. shoy (reactions) 16:38, 24 February 2015 (UTC)

Also, I had the notion that bitterness was a marker of either alkalinity or reduced nitrogen (of course, they often go together), and these substances (assuming they're really acids) don't seem to supply either. So I'm missing something.... --Trovatore (talk) 23:03, 23 February 2015 (UTC)

Bitterness is not a simple chemical property. It is a measure of the ability of a substance to bind to a subset of taste receptors -- there are over 20 distinct types of receptor that contribute to the sensation of bitterness. Their biological function is to be activated by substances that have a high probability of being poisonous. Looie496 (talk) 23:14, 23 February 2015 (UTC)

Yep, we have an article on bitter taste evolution. SemanticMantis (talk) 20:41, 24 February 2015 (UTC)

To answer the point above, hops were originally used in beer as a preservative and to balance the sweetness of the malt. Now the type or blend of hops used is an integral part of the taste of bitter beer - see Hops. Richerman (talk) 10:28, 24 February 2015 (UTC)

Our article says that, with a cn tag added. I still think the reasoning is post hoc, propter hoc. I strongly doubt anyone ever said randomly, this beer is too sweet, I know, lets add some roasted hops to make it bitter. That's kind of like saying the reason you put gas in a car is to get rid of the new car smell. I suspect there was originally some other reason for adding the hops, and the bitter taste just became standard. Also, if one has had beer made with cannabis in place of the hops, it is no less bitter, but a little bit better. μηδείς (talk) 18:08, 24 February 2015 (UTC)

So 'twas better Betty Barter bought a bit of better bud? --Trovatore (talk) 18:52, 24 February 2015 (UTC)

You want to call citation needed on hops preserving beer!? Or that someone might want a more bitter brew?! I think you're just bitter because your first response was totally wrong ;) Malt is sweet, and has many sugars, including Maltodextrin, Hops are bitter, and they act as a preservative in beer. If you want a citation for the claim that hops preserve beer, check out [13]. If you think hops have have an "effect" that is not preservation or bittering (are you implying psychoactive?), then for that. Hops are in the same family as Cannabis, but so are hackberry spp, so on the claim that hops is the closest relative to Cannabis. Next, many people dislike sweet beers. Is it that hard to conceive of? Just google /beer to sweet/ for plenty of examples. Finally, taste does not say that alcohol is "considered one of the tastes", it says that ethanol tastes bitter. SemanticMantis (talk) 20:41, 24 February 2015 (UTC)

You seem to be freaking out on multiple fronts, SM, and I would appreciate some more focus on the issues, and less on me. For example, I did not add the cn tag to the hops article. You can take that up with the article's edit history.

If by Hackberry, you mean the town in Arizona, you are wrong. If you mean Celtis, you are still wrong. Hemp and hops are each other's closest relatives.

The speculation that soma, which was brewed by the early Indo-Europeans, used cannabis is of long standing (a not necessarily RS that at least mentions references). Given that cannabis was not native to Europe, but Humulus lupulus which resembles it is, it is quite possible the Europeans substituted the latter for the former. It's simply absurd Ockham's Razor to assume people started cultivating an uncommon plant to make their beer taste bitter. As for taste, the article mentions alcohol as bitter, but other studies on the net say its taste varies according to genetics, and I have indeed read where it has been proposed as a "basic" taste like fat and umami, although a quick google search was unhelpful. μηδείς (talk) 21:56, 24 February 2015 (UTC)

Hmmm, this conversation needs to be grounded in some technical discussions of gruit that are beyond my competence. While I suppose only the most die-hard aficionados of beer would say that restricting brewers to hops was Germany's worst purity law, it should be clear that beer was once a much more diverse and interesting set of multi-ingredient herbal preparations, complete with some rather alarming "narcotics" like henbane. Damn, I forgot all about one of my past daydreams to do Michurinist graft hybridization of hops onto cannabis rootstocks (now legal in some places and highly selected to produce certain chemicals) in order to see if the transferred small RNAs would create desirable changes (but not THC production!) on the hops. Wnt (talk) 23:31, 24 February 2015 (UTC)

Comparing human and machine energy efficiency

Can humans or machines extract more energy from a gallon of fuel (food for the human, gas or diesel for the machine)? It's clear that maybe humans can walk, cycle or run a shorter distance due to all the heat being generated and lost. After all, maintaining life is more important than moving. But I'd like to know how the two compare, if we count all the energy humans are obtaining from food and all work done, not just locomotion.--Senteni (talk) 22:35, 23 February 2015 (UTC)

They both extract comparable amounts of energy, but what matters is the fraction of that energy that can be converted to kinetic energy, as opposed to the fraction lost to heat. The human body is generally thought to have an efficiency of energy conversion of around 20-25%. For machines the numbers vary so widely that it is impossible to generalize. Most gasoline-powered automobiles achieve efficiency comparable to the huma body, but diesel engines usually reach efficiencies in the 30-40% range.Looie496 (talk) 23:08, 23 February 2015 (UTC)

Poincare thought experiment

Martin Gardner in Relativity Simple Explained mentioned Poincare thought experiment, which says there would be no means to detect any change if the universe and everything in it tomorrow becomes proportionately larger (or possibly smaller). I had a quick thought: wouldn't we notice that it would take more (or less) time for the light to reach the Earth, for instance? That said, assuming the speed of light and time itself wouldn't change (a second would remain a second, a minute would still consist of 60 sec, etc), it should take more time (if the universe becomes larger) for the light to cover any distance, meaning we would notice the changed size of the universe, being accustomed to the previous size. Am I missing something? Brandmeister^talk 22:50, 23 February 2015 (UTC)

They were likely assuming the speed of light would change proportionately. StuRat (talk) 23:59, 23 February 2015 (UTC)

They explicitly tells you that everything would change, including wavelengths. The thought experiment is meant for you to realize a basic concept. In this case, you should ask yourself whether distance can be absolutely be measured or it is relative to other stuff.--Senteni (talk) 00:53, 24 February 2015 (UTC)

If I understand it correctly, a change in wavelength wouldn't imply change in the speed of light, but even if it also changes, we would certainly notice that it's not the same as previously. Brandmeister^talk 08:24, 24 February 2015 (UTC)

And how would you measure anything, if everything is half of what it was yesterday, including your ruler? If in a half-so-big universe the constants like speed of light are half of what they were, you'll have no chance of noticing a difference. — Preceding unsigned comment added by Senteni (talk • contribs) 15:13, 24 February 2015 (UTC)

I now suspect that something would definitely go wrong due to possible violations of baryon number and other fundamental constants, but that steps into the concept of fine-tuned Universe. Brandmeister^talk 17:22, 24 February 2015 (UTC)

can massless elementary subatomic particles within a single atomic structure be infinitely close to each other?66.87.83.122 (talk) 19:57, 24 February 2015 (UTC)

I assume you mean gluons which are the only known massless particles that that remain within the atomic structure (the others, photons and neutrinos are best regarded as waves for most purposes). I think they can be arbitrarily close, especially in a quark–gluon plasma. Dbfirs 21:10, 24 February 2015 (UTC)

But of course.66.87.83.122 (talk) 21:37, 24 February 2015 (UTC)

The point is that if you uniformly scale all the numbers that refer to distance, it's just like changing your base unit of distance, and has no physical consequence. If you can come up with an experiment that detects the change then you forgot to scale something. If you think the speed of light will be detectably different then you probably forgot to scale c. If you think the Compton wavelength of the electron will be detectably different then you probably forgot to scale h and/or c. Every quantity is scaled by the power of distance that appears in its units. For example c has units of distance/time so it should be scaled by k, the overall scale factor; h has units of mass·distance²/time so it should be scaled by k²; the diameter of the earth has units of distance so it should be scaled by k; and so on. -- BenRG (talk) 22:18, 24 February 2015 (UTC)

Incidentally, I don't think you should try to learn special relativity from Martin Gardner, since I don't get the impression that he understood the theory himself. He was primarily a journalist, not a scientist, and certainly not a physicist. I'm a fan of Einstein's own Relativity: The Special and the General Theory. There are cheap printed editions available and you can download it free online since it's in the public domain. Einstein was an engaging writer and he understood the theory better than, frankly, the vast majority of later popularizers. I can't recommend his section on general relativity, though, since it's based on the "general principle of relativity" which is now a historical curiosity. -- BenRG (talk) 22:33, 24 February 2015 (UTC)

The flip side of this question is whether we "really" live in an expanding universe, or whether some of the underlying physics is changing so that atoms and various other things are getting smaller. I think I asked something along this line a while before here and basically the answer is that either you're in possession of a model by which your new paradigm makes it easier to work the math, or else you have some groovy bong-hit philosophy and your dick in your hand. :) For the original question, if we suppose that every aspect of the data (and therefore the math that underlies it, is unaltered, then the change in "actual" size, that we can't measure, has to be dismissed as unobservable. Otherwise, we start doing math on whatever observations change. Wnt (talk) 23:23, 24 February 2015 (UTC)

wnt, could you clarify what you mean by underlying physics is changing? Because I would say the physics does not have to change for that to be true. It is actually a perfect fit to help explain time. Delta t is delta shrink. That is how the universe differentiates now from now. 73.160.39.193 (talk) 03:09, 25 February 2015 (UTC)

And not sure if paradigm shift makes the math easier but I did have bong hit AND dick in hand. Uncanny!2601:C:3600:46B:A926:7032:DCEE:D302 (talk) 03:32, 25 February 2015 (UTC)

What does it take to set up a personal laboratory in the 21st century?

I have heard and read that in history, people just funded their own research, and if they were broke, then they're out of luck, unless they asked a wealthy person to finance their research project or invention. Now, in the 21st century, what does it take to set up a personal laboratory in the 21st century in order to conduct research? Is the person allowed to publish research papers even without any academic degrees? Does the researcher have to take into account of ethical/safety standards, or will he/she have to put his/her own life at risk? 66.213.29.17 (talk) 23:40, 23 February 2015 (UTC)

It will depend greatly on what you want to research. If you want to compare the liver size in various frogs, that could be done pretty cheaply. If you want create a sustainable fusion reaction, that might cost a tad bit more. :-) StuRat (talk) 23:57, 23 February 2015 (UTC)

(ec)It depends on what sort of research you want to do. Amateur astronomy is easy to get in on with a small amount of investment. I'm guessing you're talking chemistry/biology/physics, though. There's a growing movement of DIY biology, including a growing number of hackerspaces with a science twist. Reagents and equipment can be obtained by private individuals from internet sites like eBay, or even from standard scientific suppliers. Keep in mind, though, that certain materials are illegal to purchase or possess without a license or some sort of official affiliation. This is particularly true for chemistry items, where the sale of things like Erlenmeyer flasks are restricted in some jurisdictions as "drug paraphernalia" (due to their use in meth labs). Regarding publishing, an institutional affiliation is not strictly required for publishing, but submissions from independent researchers are likely to be scrutinized more heavily than those from recognized institutions. Having a previous track record of scientific publishing would help in this regards - it's not that independent researchers can't do good science, it's just that the balance of probabilities are such that submissions from a non-affiliated researcher are likely to be from a crackpot, and no one wants to waste their time on improperly performed drivel. Independent researchers should take in to account ethical and safety standards - many journals will require ethical oversight of research, especially that involving humans or other vertebrates, and will refuse to consider research which doesn't have ethical oversight. Safety standards are less rigorously enforced by journals, but should be accounted for anyway - particularly as performing experiments without the proper safety precautions may be illegal in your jurisdiction. In *all* research, whether independent or institution-affiliated, a researcher should never perform experiments where their own health or welfare are put at risk - or where the health and welfare of others or the environment is put at risk. If an experiment can't be completed safely (or if it's unknown if the experiment is safe), it shouldn't be attempted in the first place. -- 160.129.138.186 (talk) 00:19, 24 February 2015 (UTC)

Partly false. Researchers can perform experiments where their own health and welfare are put at risk; indeed, this is sometimes the only person they are allowed to perform the experiment on. The most famous example is probably this, which won the experimenter a Nobel prize. RomanSpa (talk) 12:35, 24 February 2015 (UTC)

30 years ago yes. Today may be a bit different. --Jayron32 13:34, 24 February 2015 (UTC)

• It might help if you told us where you heard and read where such people existed. Was it natural historian? Were they sharecroppers, or clergy, heirs, and minor nobility? Have you read peer review? Have you read Einstein? He was published well before he earned a PhD. Give us some context so we can better assist you. μηδείς (talk) 05:28, 24 February 2015 (UTC)

• In some subjects it is possible to do research with very few resources, and, yes, you can (though it is rare) publish without being affiliated to an institution, as your paper will be subject to the same peer review process. My mother maintained a small research effort into the reproduction and behaviour of various weevils on a kitchen worktop. Total area used was about 1 sq metre, and academic output was principally in the form of correspondence with the Royal Entomological Society. Amusingly, her interest was piqued by finding an infestation in a bag of flour.

My niece is currently breeding Drosophila melanogaster in her bedroom. Academic output so far seems to be a couple of essays for her school biology class. Cost is negligible, as she is now using her grandmother's microscope. RomanSpa (talk) 09:28, 24 February 2015 (UTC)

Perhaps it is instructive to point out that much research and development takes place in the private sector. If a private company wishes to hire and fund your research, they may choose to do so, irrespective of your credentials. Generally, well-credentialed people have an easier time getting other people to take them seriously, so it's very common to find that an academic degree is an "implicit" prerequisite. There are exceptions: one Peter Thiel will aggressively fund ideas and individuals of his choosing, provided that the youngster signs a contract obligating them not to take any academic training. This is a notorious exception: Mr. Thiel, however wealthy or successful he may be, is a crackpot. Nimur (talk) 15:09, 24 February 2015 (UTC)

February 24

Chemical composition of Steam

If I wanted to know if something was burned by steam , and the residue was carbon , what would the exact chemical composition(formula) be if it was tested , and steam or water was the cause or present , for instance if metal or an alloy was extremely hot and cooled down suddenly and shattered and left a carbon residue and was tested what would the chemical formula be does anyone know ??? or apart from everything else will H2O be present no matter what ?? — Preceding unsigned comment added by 165.143.155.57 (talk) 06:40, 24 February 2015 (UTC)

If carbon residue is left by steam, it wasn't steam, it was smoke. Carbon residue means soot is present, and carbon is not water. Steam is gaseous water (H₂O) has no carbon in it. If it leaves carbon, it had carbon to begin with. --Jayron32 12:28, 24 February 2015 (UTC)

You might also want to read about how real-world fire investigation uses forensic evidence to draw conclusions about a catastrophic event. NIST even offers a program on the topic, with several books listed as sources: Disaster and Failure Studies. Nimur (talk) 14:55, 24 February 2015 (UTC)

Is there a maximum time limit to a human courtship?

Courtship explains that in the UK, people court about 2-3 years. This does not mention statistical outliers. In that case, what is the longest human courtship known? 5 years? 10 years? 25 years? 50 years? 140.254.136.182 (talk) 18:47, 24 February 2015 (UTC)

One famous outlier was Michael Winner who married 70-year-old Geraldine Lynton-Edwards when he was 75. They had been courting for 50 years, on and off. Dbfirs 18:56, 24 February 2015 (UTC)

Although he apparently had women in his life - including a prior marriage. Hard to count is as a courtship in the circumstances. Collect (talk) 19

10, 24 February 2015 (UTC)

This might be better asked on the Humanities desk. -- LongHairedFop (talk) 19:26, 24 February 2015 (UTC)

Collect's comment above along with Dbfirs example sort of hinted at this. I think this question (as with many) is basically impossible to answer, unless you come up with a precise and clear definition of courtship. (Well even then it's probably impossible to answer since it's unlikely to be something recorded.)

Our article uses, "Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. During courtship, a couple get to know each other and decide if there will be an engagement or other such agreement." It also mentions how courtship practices vary significantly.

Consider the example above, they seem to fit within this definition for the 50 years or so, yet a both Dbfirs and Collect hinted at, many wouldn't count the whole thing as courtship.

Or consider if two people meet as young kids, perhaps they become friends. They stay that way for many years. At some stage they realise they have romantic feelings for each other, and begin a dating. Under the definition used in our article, it would seem you should count the time from when they first met, but I think many would only count around the time they began to realise they have feelings.

Yet that isn't simple either. What happens if only one party initially develops feelings, and it takes a long time and a lot of effort before the other party does likewise (probably most such relationships end in disaster but you did ask for outliers)?

Or if you're taking the looser definition, what about if the couple meet as children and then lose touch for many years? What about if they meet and know each other but have only minimal contact?

As for my earlier point of differing practices, on Collect's point, even if not true for the above case, in some cultures polygamous (mostly polygynyous) marriages are acceptable. In such cases it may be acceptable for one partner to be publicly courting another person while already married. Of course in many cultures, publicly courting multiple woman may be acceptable at least at an early stage.

Our article mentions UK averages and also the earlier point "establishment of an agreed relationship of a more enduring kind". In the UK and some other countries, it isn't exactly uncommon for a couple to start cohabitating before even engagement. Are they still courting then?

It definitely doesn't fit many traditional definitions of courtship, even in these countries. Note in some countries, e.g. NZ such a relationship may have legal implications at some stage perhaps being treated very close to a marriage, but will legally never be a marriage without the formal process. And depending on the couple, the engagement and marriage, while perhaps important, may not be that important. (And also sometimes may only come after many years of cohabiting and describing each other as partner or spouse, kids, basically everything you'd expect in marriage except the certificate, except of course marriages themselves existed long before certificates and there are still plenty of places where it isn't necessary for something to be legally considered a marriage. In fact sometimes they may never get married, see my later point.) Yet if you count the cohabiting as the end of courtship, consider some may jump in to this extremely readily, and perhaps even stop doing it due to relationship problems a few times and not really consider their relationship anything that special at least the first time they are cohabiting.

Also are you only counting successful courtship? In other words, if a couple spend a lot of time together developing a romantic relationship but it ultimately doesn't work out, are you counting this or not? Consider if you require a successful marriage proposal, or even a marriage, you're ruling out for example, a case where a couple a courting and one party plans to propose to the other and the other party basically knows and tells several people close to them (and it's clear they will accept), but one of them dies before this can happen. (Or alternatively one person dies before marriage.)

Nil Einne (talk) 20:08, 24 February 2015 (UTC)

I know a couple who were engaged for more than thirty-five years. They were finally married in summer 2014. Not a dry eye in the house, apparently (I wasn't there myself - don't know them that well). RomanSpa (talk) 23:24, 24 February 2015 (UTC)

The second Google hit on longest courtship is from 1915 and says: "The longest courtship on record ... seventy-five years".[14] PrimeHunter (talk) 23:25, 24 February 2015 (UTC)

Growing outside the womb

You know how some species like chickens lay eggs? Well, is it possible to make an artificial "egg" for a human fetus? At birth, will the human fetus have the ability to kick out of the shell? Who will nurture the child when it's born? 140.254.70.33 (talk) 23:04, 24 February 2015 (UTC)

Artificial wombs are an appealing idea, but ... let's be realistic. Infant formula, replacing the seemingly simple nutritional recipe of breast milk, is so laughably deficient that many studies have found the babies to lose 5 or 10 points of IQ from the unwholesome substitution. Breast milk isn't even alive and we fall flat on our face trying to replace it. Much the same can be said of blood substitutes; whenever some group of luckless souls becomes the newest victims of the doctrine of "community consent" to some Frankensteinian experiment at the cellular level, double digits more people die than would have died if given normal blood transfusions. Now imagine that instead of trying to replace a mere fluid, you're trying to replace a living human woman, with many endocrine glands, bone marrow, digestive tract, even the occasional inscrutable but likely vital instinctive call for pickles and ice cream, all responding to the pregnancy. This is an idea that will be proposed ten thousand times but never happen. Wnt (talk) 23:14, 24 February 2015 (UTC)

What about babies that are breastfed AND cowmilk-fed? Does that decrease IQ? (I was one!) 140.254.70.33 (talk) 23:33, 24 February 2015 (UTC)

Neglecting the hyperbole, the answers to your questions are: No, it is not possible to make an artificial "egg" for a human foetus; No, the child will not have the ability to kick out of the shell, because (a) the shell is likely to have to be fairly thick to hold the amniotic fluid in place, and (b) humans do not have that kind of instinctive kick reaction at the moment of birth; No-one will be needed to nurture any children born in such as way, because nobody is going to be born that way any time soon. Despite the previous comment, it is impossible to permanently rule out this technology, but it is unlikely to happen in the near future. A technology of this kind would certainly save lives (pregnancy carries substantial risks for the mother), but is a long way from being developed. RomanSpa (talk) 23:38, 24 February 2015 (UTC)

Agreed that just because we can't do it now, that doesn't mean we will never be able to do it. After all, we have artificial bone, teeth, and (temporary) skin. That said, this seems similar to the "living head in a jar" concept we often see in sci fi, which presumably is also a long way off. StuRat (talk) 23:57, 24 February 2015 (UTC)

February 25

How are contactless credit cards protected against electronic pick-pocketing?

Couldn't a tech thief adapt a credit card processing machine to collect payments in crowded places?--Senteni (talk) 00:29, 25 February 2015 (UTC)

Can one get his entire/whole vas deferens removed?

As in, is it practically possible (for a doctor) to do this?

After all, vasectomies can fail, and thus, I am curious about whether or not it is practically possible to do this. Futurist110 (talk) 04:33, 25 February 2015 (UTC)