Peripheral sensory cell > Preganglionic cell > Dorsal root ganglia cell in the Sympathetic chain > Ventral root ganglia cell in the sympathetic chain > Post-ganglionic cell that activates an organ such as the pancreas (or a muscle).

Was I accurate? I ask this after feeling that some books\people tend to confuse the details of this axis... :|

Thanks, Ben-Yeudith (talk) 03:30, 17 November 2015 (UTC)[reply]

That pathway might come into play, but it wouldn't generally be called a "fight" response unless brain circuitry is involved. See fight-or-flight response, and for further information sympathetic nervous system and norepinephrine. Looie496 (talk) 14:31, 17 November 2015 (UTC)[reply]

Why does dehydration cause swelling of various body parts? 2A02:C7D:B8FF:7E00:A9FD:A524:5C8A:311F (talk) 09:06, 17 November 2015 (UTC)[reply]

I don't see anything in Dehydration that talks about swelling. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:14, 17 November 2015 (UTC)[reply]

Perhaps the questioner is thinking of the abdominal swelling seen in severely malnourished children. See here for some explanations. AndrewWTaylor (talk) 11:37, 17 November 2015 (UTC)[reply]

Kwashiorkor isn't a dehydration symptom (it's the product of a specific kind of malnutrition), but might be what the OP is thinking of. See also Swelling (medical) and edema. 99.235.223.170 (talk) 01:43, 19 November 2015 (UTC)[reply]

What about gorse bush prickles causes an inflammatory response? Getting prickled by gorse bushes causes an inflammatory response so the pricks appear as red spots which persist a couple of days following exposure. A friend said it was "phenolic compounds" but I can't find anything about it online. --129.215.47.59 (talk) 11:34, 17 November 2015 (UTC)[reply]

This [1] says that formic acid is present. SemanticMantis (talk) 15:20, 17 November 2015 (UTC)[reply]

Thanks but I think you misread the source. The formic acid is in nettles. --92.6.114.248 (talk) 20:54, 17 November 2015 (UTC)[reply]

The source provided says (quoting directly)

• 78. Ulex europaeus
• Common names:- Gorse
• Part used:- flowers
• Effects:- some astringent action, flea repellant
• Chemicals present:- tannins. No further data available at the present time.

Relevant here is the statement that it has astringent properties which are likely caused by tannins. --Jayron32 21:20, 17 November 2015 (UTC)[reply]

@92.6.114.248: related event, this was caused by an 'inflammatory response' other then the gorse itself:

• "Dog walker killed by a scratch from a gorse bush" Daily Mail, May 2006.

The 74-year-old woman actually "... died from the 'flesh-eating bug' necrotising fasciitis" caused by "group A streptococcal infection". 220 of ^Borg 22:47, 18 November 2015 (UTC)[reply]

Yes, the Daily Mail headline suffers from the post hoc ergo propter hoc fallacy: She was killed after the scratch, by something unrelated to the nature of the cause of the scratch. --Jayron32 23:42, 18 November 2015 (UTC)[reply]

Like "We all eat food, and drink water and we all die", therefore: "Don't eat, or drink water, and you will never die"? No, I think that's Correlation does not imply causation. - 220 of ^Borg 06:02, 19 November 2015 (UTC)[reply]

I see many sites, including Wikipedia, explain macro-nutrients and dieting like this (loosely and poorly paraphrased):

Proteins and carbohydrates contain 4 kcal per gram, and fats contain 9 kcal per gram. Thus your daily total energy intake is (proteins[g] + carbohydrates[g]) * 4 kcal/g + fat[g] * 9 kcal/g.

If you consume more food energy than you use, you gain weight. If you consume less food energy than you use, you lose weight.

Which makes a lot of sense to me.

I'm wondering whether the "9 kcal of energy per 1 gram of fat" figure can be also used to calculate the amount of weight loss (or gain) as well. Suppose someone is achieving a consistent a 90 kcal energy deficit per day for a long period of time. Does that mean they will be consistently, averaged over a long term, losing 10 grams of fat per day? Assuming the person lives a sedentary lifestyle and thus has no muscle gains or losses. 731Butai (talk) 06:29, 18 November 2015 (UTC)[reply]

I don't believe it's reversible like that, no. Also, while this would be true: "If somebody reduces caloric intake in one way without increasing it in any other way while still burning the same amount of calories, then they should either lose weight or at least gain weight more slowly". Unfortunately, in the real world, it's not as simple as that. When they eat fewer calories their body notices and torques up hunger to get them to consume the usual amount. And/or it may decrease the basal metabolic rate (they may feel colder) and the lack of energy may make them more sedentary than they were previously. One notable example of all this is that when people switch from regular soda to diet soda, which contains fewer calories, they do not lose weight. StuRat (talk) 06:59, 18 November 2015 (UTC)[reply]

(2 edit conflicts.)(I slightly reformatted your question for readabiltiy reasons.) StuRat you are not wrong, but s/he says "consistent a 90 kcal energy deficit per day" which undercuts your exceptions. The answer is yes, with possible complications. There are more ways to store energy, for instance glycogen, which is short term storage of linked glucose, 4kcal/g. This is used first, it is more readily available. But it is the first to be replenished. So deficit has to go somewhere, and assuming full grown adult and no other tissue or muscle losses, and averaged over a long time, so answer is yes. You can also estimate volume change if you look up density of fat (a little less that water). Phun Phact: A gallon of gasoline has 33.7kWh = 28976. kcal. If that were fat it would have mass of 3.2 kilograms= 7 pounds. Takes a LOT of work to get rid of it. GangofOne (talk) 07:14, 18 November 2015 (UTC)[reply]

The basic arithmetic and chemistry works - but the underlying assumption that energy consumption doesn't change is the 'gotcha'. If you live in a cold climate - and have a perfectly balanced diet, so you're neither gaining nor losing weight - then buying a better jacket can cause you to put on weight. You're using less calories to maintain body temperature - so you need fewer calories than you did before.

The claim is that the body "goes into starvation mode" when you eat less, and that this can defeat your efforts at dieting...and that when you stop dieting while "in starvation mode", you'll pack on the pounds very rapidly.

This seems superfically plausible - but the problem with this claim is that (although I've searched and asked this question all over the place) I can find no concrete evidence for it. Clearly there is some kind of effect - but nobody seems to know how much calorie deficit causes the "switch" to turn on - or for how long you can go on a deficit diet before it turns on - or how strong the effect is - or for how long it remains on after your diet returns to normal. It's astounding that roughly 50% of all dietary advice repeats this "information" - but nobody seems to have any kind of solid research evidence to back it up. Since (if true) it's a critical piece of information for all diets - this is horrifying.

Some diet guides tell you to come off your diet periodically (say once a month) in order to 'reset' the starvation mode thing - suggesting that the "starvation mode" thing operates over a scale of weeks. Other people tell you it's vital to eat a good breakfast in order to avoid flipping your body into starvation mode before lunchtime - suggesting that "starvation mode' happens over a matter of hours. This is bullshit "cargo-cult science". Without solid experimental facts, the best guess is that the body has evolved to operate efficiently at all times - and that if "starvation mode" existed, we'd notice serious deficits in performance. I've actually tried to see this happen in myself...switching back and forth between regular soda and sugar in my coffee to diet soda and artificial sweetener - or going onto a 1000 calorie "juice-only" diet. Neither of those things cause me any mental impairment (beyond the occasional craving for a Sonic #4 meal with extra tater tots and a medium chocolate shake), there is no measurable drop in my body temperature or any obvious lack of performance of any kind...and my rate of wait loss is pretty much as predicted by the calorie restriction. Now, I might be a weird outlier - but tell me how this supposed "starvation mode" is saving energy? Is my hair growing more slowly? What precisely is being eliminated to save all that energy?

Yet, this claim for "starvation mode" is repeated everywhere - and with random claims for how long it takes to go away, how much it takes to trigger it and what percentage or calorie-count difference it makes to energy consumption.

The diet industry is worth billions - why no solid research findings?

That said - if anyone knows of a decent empirical study that answers those questions...I'd love to hear about it.

Bottom line - you need to eat fewer calories to lose weight - the difference between the various diet tricks are all to do with how well you can stick to them - and that's down to glycemic index - how long you can go with less food and not feel so insanely hungry - bottom line of which appears to be to eat relatively indigestible foods that stay in your system for longer. SteveBaker (talk) 15:54, 18 November 2015 (UTC)[reply]

Steve, have you read the empirical study cited at Starvation_response#Magnitude_and_composition? It discusses how the energy is saved, and that info is also summarized in our article section. Ref [6] there also looks interesting. I'm sure there are more empirical studies, but those were the easiest to find. At a glance, this study [2] cites a lot of empirical research on human starvation response, and might be a good way to get more sources that cover your interests more specifically. Here's [3] a whole article in the prestigious Annual Reviews series summarizing what was known in 2006 about the physiological responses to food deprivation. There's also a lot of mechanistic studies that show what factors mediate things like macroautophagy, like this one [4]. Look, this is complicated and subtle stuff, but please don't call it cargo cult science. Just because some sources play fast and loose with claims and implications does not mean that there is not serious, peer-reviewed empirical science available on the topic. SemanticMantis (talk) 17:54, 18 November 2015 (UTC)[reply]

The studies that you cited above refer to extreme starvation - complete food derivation and were actually about animals. I doubt that there are serious studies of humans under conditions of moderate food deprivation as is often the case in diets. I also doubt that a moderate food deprivation induces changes so significant to seriously slow weight loss. Ruslik_Zero 19:46, 18 November 2015 (UTC)[reply]

I have read Starvation_response#Magnitude_and_composition (did you?). It starts off by talking about a on-off study done on just 8 people who'd been cut off from the world in the ill-fated Biosphere2 experiment. Aside from the fact that this is vastly too small of a sample to draw any conclusions whatever - these people were initially selected for the Biosphere2 experiment based on all sorts of criteria that separate them out from "average" humans. The effects they noted explain calorie requirement reductions that amount to about 180 calories/day...which is not much of a drop from normal - just what you'd get by replacing one and a half cans of soda per day with diet soda - and certainly not enough to prevent a modestly aggressive calorie reduction diet plan from working! They describe about a third of those savings as "statistically insignificant"...and with all of the other horrible things that happened to those 8 people during their weird "experiment", I could believe they were screwed up in so many other ways as to make any conclusions utterly invalid...so meh...not "cargo cult science" - it's "very, very bad science" and with conclusions that have zero bearing on the question at hand here.

As for the remainder of that section, it discusses in mind-numbing detail how a TOTAL fast (zero calories) causes various energy stores in the body to keep the body running normally. This is not what people are talking about when they claim that the body might flip into a mode where it DOESN'T burn much fat when calories are somewhat restricted by somehow turning on a more efficient energy consumption switch. Quite the opposite in fact - it's saying that if you eat less, your fat reserves get used up in trying to continue to power the brain...which is precisely what you'd hope your diet would do for you! Far from making me think that this supposed effect is "real" and well studied - it makes me believe the complete opposite! Our bodies will work to consume all of our fat reserves and then switch to consuming our muscles and other proteins in a concerted effort to maintain the usual amounts of energy production despite low to zero calorie intake.

OK - so having dismissed what our article has to say...what about [5]? Well, this study was about the effects of Human Growth Hormone on starving (ie ZERO calorie intake) obese people - so the test group getting HGH supplements aren't telling us anything of value because we're not going to be doing that while dieting. The control group lost a heck of a lot of weight - there are descriptions of how and why - but no indication of the things that matter for people on a diet (How many calories can I cut without turning on "starvation mode"? How much energy will my body save when going into this supposed more-efficient-metabolic state? How quickly will that effect rebound? ...and so on). That article in no way addresses the questions that need to be answered on this matter. Also, it's talking about complete starvation for weeks! This is not a scenario we care about. I want to know what happens when I do a "sensible diet" and go from (say) 2,500 calories per day to 1,500 per day - and I'm not taking any HGH!

How about your third reference [6]? Well, it *might* be useful - but it's behind a pay-wall and the abstract doesn't look promising. It doesn't mention humans at all (although "animals") - and we know that the human body responds differently from other mammals in terms of how our brains keep functioning during periods of starvation - we specifically DON'T shut down brain functions when food is in short supply - and there is biochemistry in your first and second sources to back that up. What the abstract says is that during periods of starvation, "animals" (unspecified) lower "spontaneous activity" and body temperature. Well, I know that during a 10 day "juice-only" 800cal diet that I did, my body temp didn't fluctuate at all (I was tracking it every day for a different reason). I still went to work and did all the things I usually do in evenings and weekends...I lost 10lbs...but I don't think a "starvation mode" switch was flipped at all (although - I definitely felt pretty amazingly hungry the entire time). But STILL - I see no data about how little I can eat without turning on this supposed switch - or what the effect of flipping the switch is on energy requirements - or how rapidly it turns back on again. NOTHING.

Then we have [7] - which is frankly incomprehensible to the layman...which is OK - but it doesn't mention anything about how little calorie intake is required to trigger these changes - or (AFAICT) how much these cryptic changes reduce energy needs within the body. Maybe you could summarize the results for me - but I suspect the article has no bearing on the question at hand since it only seems to discuss mechanisms at the cellular level and not whole-body responses.

So again...tell me where I can find the answers to the following three questions:

1. How few calories can I eat without triggering this response?
2. Having triggered the response, how many fewer calories will my body consume?
3. How long after providing more calories than the answer to question (1) will my body return to non-starvation mode?

Those three questions are critical to either supporting the notion that modest amounts of dieting doesn't work - or debunking that idea.

Until we know that - anyone who trots out the old argument that if you cut your calorie intake, you won't lose weight because of this mysterious "more efficient metabolism" is indeed indulging in cargo-cult science...and that includes nearly every contributor to every discussion we have on this subject here on the Ref Desk. Show me the references!!

SteveBaker (talk) 20:23, 18 November 2015 (UTC)[reply]

Look, I'm not going to try to support your "old argument that..." claim, because it's obviously not true. Also, I'll note that the Annual Review ref has lots refs and results for humans - we are animals too, and you can ask at WP:REX if you'd like a copy. Your skepticism of the existence of the starvation response is... puzzling, and I'd like to give more general refs that support the claim that "type and amount of caloric intake can alter human energy budget, including baseline metabolic rate, as well as amount and type of weight lost. Additionally, humans can specifically alter their energy budgets to use less energy when undergoing some level of caloric deficit for sustained periods." This doesn't rest just one paper, there are many, just use google scholar to find more. After some more searching, I found a freely accessible article specifically about metabolic changes in humans on different weight loss diets of 1,200 and 800kcal, with and without ketogenic diets, and also with starvation [8]. Patients' base metabolic rate changed by a maximum of -18.9%. So doubt all you want, but my reading of this article is that it shows good evidence that in human subjects caloric restriction can alter the base metabolic rate and total energy balance, e.g. a "starvation mode" that is real and empirically supported, and can occur in realistic weight loss diet plans. Here's another study that looks at the effects on baseline metabolism due to 24 weeks on a "semistarvation" diet of about 1600 kcal [9]. Figure 1 there shows how many less calories were burned, and your questions about how much restriction and for how long are answered for at least this one case - 1600kcal and 24 weeks, note also the results on the recover phase. There's still a lot more work to be done of course, e.g. it would be nice to have a fully factorial kcal/time design, but I don't think that's likely to exist. But I will no longer argue with you about whether or not the human starvation response is "cargo cult" science. The effect is almost certainly real, despite the fact that you don't think that your 10 day juice diet changed your BMR. I don't know or care anything about weight loss, and make no claims about it. My primary intent here is to give scientific refs that quantify the starvation response in empirical studies of human subjects. SemanticMantis (talk) 20:46, 18 November 2015 (UTC)[reply]

Aha! Thanks for that - the first of those references makes a lot of sense - I'm still reading the other ones. We really should get into the Starvation_response#Magnitude_and_composition article and put some of this stuff into it. It shouldn't be necessary to dig so deep to find this stuff out - and that's what Wikipedia is good at doing. SteveBaker (talk) 16:12, 19 November 2015 (UTC)[reply]

I seriously doubt that it's as simple as a binary switch that gets thrown when you hit a certain calorie restriction and that then resets after some period on a normal calorie diet. Some complexities:

A) It's more of a continuum than a switch. That is, the fewer calories you consume, the more "nonessential" functions will be reduced or eliminated. At a modest calorie restriction, presumably the effects would be rather unnoticeable, like slower hair and nail growth.

B) Specific nutrient restrictions can have different effects. For example, a lack or protein can cause "brain fog". In other cases, the response only occurs as a result of other body changes. For example, women's periods will stop if their body fat drops below a certain percentage. The body fat percentage may or may not be related to calorie restrictions.

C) There's no reason to expect that the starvation response would be identical for every person. Is the ability to tolerate cold or heat identical for every person ? Of course not. So why would this be identical ? Presumably people descendant from populations facing regular starvation would have a stronger starvation response than others.

D) Also note that serious calorie restrictions may cause permanent damage, so to study that in humans in a controlled experiment would be unethical. StuRat (talk) 04:09, 19 November 2015 (UTC)[reply]

I know from personal experience that eating little you can lose roughly half a pound a day for long periods, though it's not all fat of course. My feeling is that "to an order of magnitude" this is correct, bearing in mind that changes in fluid volume both intracellularly and extracellularly can easily overwhelm the fat-based effect. Wnt (talk) 16:03, 18 November 2015 (UTC)[reply]

The description of starvation response may be accurate for normal people, but it seems to have little relevance for the obese. After all, improving metabolic efficiency in that case involves things like reducing insulin resistance and lowering blood glucose, which are desirable in themselves; indeed, a person may undertake a diet primarily to trigger this kind of response. Wnt (talk) 09:48, 19 November 2015 (UTC)[reply]

It seems that ruling people out solely based on DNA evidence could exonerate guilty parties who exhibit chimerism. Unless a rape suspect, for example, is tested for sperms, which I find unlikely, they could be set free if there is no other evidence. How big of a problem is this? 69.22.242.15 (talk) 14:19, 18 November 2015 (UTC)[reply]

Our Chimera (genetics) article doesn't explain this, but there is growing evidence that people do sometimes (perhaps often, perhaps always) carry around some DNA from their mothers, and that mothers sometimes collect DNA from their unborn children (see THIS for example). So...to be sure that DNA obtained from (say) a blood test would correctly match (or not match) sperm in a rape case - or something of that nature, is indeed, theoretically, problematic. Since this is a relatively new discovery, I think it's too early to guess how much of a problem this is. However, the chimeric DNA will always be from the person's mother, child (if female) or weirdly unborn twin - so the DNA from one part of the body will always have half of the genetic information that the DNA harvested from elsewhere would contain. So it should be relatively easy to fix the problem once it's better understood. My gut feel is that it would be exceedingly rare for this to change the outcome of a legal case though. In the specific example you propose, a man who had committed rape couldn't have sperm cells from his mother, or his child - so it would have to be the "weirdly unborn twin" thing - the twin in question would have to be fraternal, not identical, and would also have to be male...and the testes cells would have to have come from the twin - and not (say) the heart or the brain or some other place where blood cells are not made. The error could only be in the wrongful dismissal of the case - not a wrongful conviction. It would also have to be a case where DNA was the only factor in the dismissal - in the teeth of eye witnesses and other DNA sources such as hair and skin. This narrows the odds considerably...so I'd say that the odds of a wrongful dismissal ever having happened as a result of this would be very slim indeed. But until we have better information about the incidence, all bets are off. SteveBaker (talk) 15:03, 18 November 2015 (UTC)[reply]

FYI, our article on the "weirdly unborn twin" thing is at vanishing twin. 99.235.223.170 (talk) 01:46, 19 November 2015 (UTC)[reply]

Lydia_Fairchild is a good example of legal issues surrounding chimerism, but not a criminal case. This [10] paper on the topic of legal issues and human chimeras. It seems to be written by a law student and not peer-reviewed, but it does have many additional refs. SemanticMantis (talk) 15:33, 18 November 2015 (UTC)[reply]

Chimerism can actually be acquired, in particular by mothers during pregnancy. [11] This means that it is possibly, by amplifying Y chromosome DNA, to identify the father of a previous child without having access to its DNA, or even (though this is more difficult and less certain) to amplify the Y-DNA of the father of a previously aborted fetus. You could use this to show if a woman had been held prisoner somewhere and forced to give birth, or to demonstrate (by forcibly taking a sample, e.g. under some legal process) that a couple had had sexual relations leading to pregnancy even though both of them deny it and other evidence is lacking. It is actually possible that the effectively transplanted cells have health effects (this ties into fetal stem cell research), and the question of how the woman develops immunological tolerance is of great interest.

I tried to illustrate this with a real world example, only to be attacked by the resident bureaucrats here - in the interest of trying to get something to stand in this entry I have posted this more generalized description. Just as the best way to enrage ISIS is not to attack them with bombs, but to enjoy our freedoms to draw and criticize and deface books to whatever degree we may still have them, the best way to enrage those whose interest is in policing is to focus on enjoying our endless scientific exploration. But I apologize for the incompleteness. Wnt (talk) 15:32, 19 November 2015 (UTC)[reply]

You may need to see a chiropractor, since you may strain yourself patting yourself on the back so vigorously. --Calton | Talk 09:06, 21 November 2015 (UTC)[reply]

There have been previous discussions on wormholes, e.g. Wikipedia:Reference desk/Archives/Science/2010 July 2, but this article is certainly interesting. It says there is a hypothesis that quantum entanglement is the basis of gravity, and indeed, that "ER = EPR", i.e. that the entanglement of two particles is equivalent to the formation of a wormhole! But there are some things I don't really get.

To begin with, there's the matter of multiple entanglement. I had thought I had read of cases of multiple particles being entangled, which is in no way like the geometry of an EPR bridge; but apparently there is a strong restriction in favor of "monogamy of entanglement". This concept is discussed somewhere around 20-30 minutes into a lecture here cited by the article above. Our article on quantum entanglement doesn't use the term; Susskind specifies that it is monogamy of maximal entanglement.

Monogamy is used in an example by Susskind about 38 minutes in... the problem is that it seems moronic to me. Note I am aware that as he is the quantum physicist and I am definitely not, this implies some principle of relativity at work! The idea of the "AMPS paradox" he describes is that any small patch of space may be entangled with a small patch of space nearby; yet a small patch of space just inside the event horizon of an "entangled black hole" cannot be entangled with a patch just outside it. The problem I'm having is, his patches of space A and B look to me like they were sitting there before he dumped N buckets of entangled matter into the area to make it a black hole, and their affections should therefore not be part of the black hole's entanglement. Indeed, how could anything dumped into a black hole linger just beneath the event horizon? Yet this seems to be the whole basis in that lecture for introducing the idea that the entanglement extends to a macroscopic wormhole.

Another issue is the "tensor network" - is this some kind of super entanglement? The graphic in the Nature article shows entangled pairs as being the outer edges of some kind of graph. While each pair is linked, it looks like each entanglement is linked to some other.

More basically, is this implying that every particle must be entangled with some other, and we just might not know which?

And as for space... Susskind draws a line down the blackboard, says this patch on the left will be entangled with this one on the right (i.e. if there's a virtual particle here there must be one there). I assume because of monogamy, that's a simplification, since each can only be entangled with one other which might be in any direction??

Then there's my main confusion with wormholes. The one thing I think I know about black holes is that when you fall in one you go down. Yet a traversible wormhole seems to be based on the notion that you can go back and forth! And the other thing I think I know is that you don't come back out... yet here they show black holes compared to entangled particle pairs where the kind of test done on one is somehow communicated to the other. On the plus side, 'monogamy' is consistent with the EPR bridge being between just two worlds. In the earliest days people imagined the target as a white hole; now it's seen as a black hole that emits Hawking radiation... it leads me to vain speculations.

Anyway, can people tell me something about this, or better still, write about half a dozen articles about these new concepts: monogamy (physics), AMPS paradox, the tensor network (whatever it is), ER = EPR etc.? Thanks! Wnt (talk) 15:34, 18 November 2015 (UTC)[reply]

I redirected AMPS paradox to Firewall (physics).

I don't understand entanglement monogamy, but presumably it means there are no systems of 3+ particles that are analogous to a Bell pair, which is a maximally entangled 2-particle system. There are nonclassically entangled systems of 3+ particles, such as the |000〉+|111〉 state used in the GHZ experiment, but they are in some sense not maximally entangled. The article Concurrence (quantum computing) says it means "the concurrence of a qubit with the rest of the system cannot ever exceed the sum of the concurrences of qubit pairs which it is part of."

A crucial part of what Susskind talks about, that he never mentioned by name in the part of the video I watched, is black hole complementarity. This is what he's talking about when he says that A and B' are the same thing (at around 45:00).

File:PENROSE2.PNG

The wormholes here (Einstein–Rosen bridges) are not traversable. It would be bad (causality-violating) if they were traversable. The causal diagram (Penrose diagram) that Susskind draws on the board at around 50:30 is the upper left diagram in the image on the right. The wormhole "throat" he draws is a horizontal slice through the center of that diagram, with the circle at the middle of the throat being the middle point of the diagram. Because it's a horizontal (hence spacelike) slice, you can't have a worldline lying in the slice, so you can't go through the wormhole he drew. As shown in the Penrose diagram, no timelike or lightlike worldline can pass through both exterior regions, but worldlines from the two exterior regions can meet in the shared future interior region. In other words, if you make a Bell pair of black holes, and toss Alice into one and Bob into the other, they may meet and exchange information inside, but no one who stays outside the first (resp. second) black hole can learn anything about Bob (resp. Alice).

It's not clear to me if this is supposed to be related to the nonclassicality of entanglement. I doubt Susskind would argue that violation of Bell's inequality is due to some sort of communication through the wormhole, because you can't use entanglement for nonlocal communication, and Susskind (like Einstein) is the kind of person who believes that sort of thing isn't true by accident. No possibility of a FTL radio means fundamentally no communication going on. But he might think that violation of Bell's inequality is somehow necessary for wormholes to make sense, even if we don't understand how yet. -- BenRG (talk) 01:18, 19 November 2015 (UTC)[reply]

I don't understand the math [I don't even know the meaning of the subscripts for the C²_A(BC) thing) but this seems to detail the math; also this if I can unglaze my eyes for a couple of hours, perhaps. (The combination of GHZ entanglement monogamy provides sufficient keywords)

As for the Penrose diagram... what mystifies me about it is that the two universes are supposed to touch at the central point (indeed, in the lecture Susskind seems to diagram "adjacent" points that seem to be in the throat of the wormhole) ... yet to cross the wormhole you have to pass through an event horizon and fall down (i.e. move straight up?) for some time. More generally, I am confused by the dramatic difference between the stationary and rotating solutions. Any black hole should have at least a tiny bit of rotation, yet... I don't see how that elaborate timelike-wormhole diagram converts to the one we see at left. Wnt (talk) 15:15, 19 November 2015 (UTC)[reply]

Each point on the 1+1 dimensional Penrose diagram represents a 2+0 dimensional sphere in the 3+1 dimensional space, concentric with the center of the black hole. The points on the X that separates the four regions are spheres with a radius equal to the event horizon radius, and are in fact the event horizon. So the two exterior regions touch at a sphere that's part of the event horizon, and a tachyonic worldline can cross between the exterior regions without entering the black hole interior (just grazing the event horizon at a point). The circle that Susskind draws at 53:38 is a great circle of that sphere (only a circle because what he drew is a 2D slice of the 3D ER bridge), and the rest of the surface is all outside the horizon (one exterior region above the circle and the other below). Both directions away from the circle are "up", though I think that makes little sense when you're talking about an instantaneous spacelike slice and a tachyon that can ignore causality.

As you say, Susskind's diagram is of a nonrotating black hole, and the theoretical interior of a rotating black hole is totally different, and doesn't seem to fit as well with his entanglement-monogamy idea. Generally people say that the rotating hole interior with its many exterior regions is unphysical (possibly because of the infinite-blueshift inner horizon), and Susskind may be using the Schwarzschild Penrose diagram for a Bell pair of rotating/charged holes because he thinks they would have the same spacelike singularity and causal structure.

Re black vs white holes, it's an interesting open question in quantum gravity to what extent that classical distinction makes sense.

The diagram from Hawking's paper (right) makes black hole formation and evaporation look highly asymmetric in time, but viewed from the outside it seems completely symmetric (except that evaporation is more chaotic than formation, but all "time symmetric" phenomena are like that because of the second law of thermodynamics). Many people think Hawking's diagram is wrong, but there seems to be no way to avoid a time asymmetry classically (the horizon needs to either expand or contract at c; it can't do both or neither) so many people also think the GR model of black holes is fundamentally wrong. Black hole complementarity is a way for the time-symmetric outside picture to be correct without abandoning the equivalence principle.

Re actual traversable wormholes (and pretending they're possible), first, they needn't have anything to do with black holes. They can just be portal doors. In the case of a traversable rotating/charged black hole, you can see from the diagram that you can choose to hit the singularity or not, then if you avoid it you will necessarily be ejected from the past event horizon, then you can choose to fall back in or not. Avoiding the singularity and not falling back in might require very powerful rocket engines. I've never seen a calculation of that. -- BenRG (talk) 21:16, 19 November 2015 (UTC)[reply]

Thanks for an informative answer... I actually had been told here before about what the wormhole spacelike section actually meant, but managed to confuse myself again after. :( Wormhole actually explains it pretty well - an event horizon linked to two universes, one in the past, one in the future, joined at the "throat". True, these in the projection are simultaneous... but I suppose I'm looking at the cross section of some object in spacetime with a high symmetry?

As for Penrose diagrams, I have to admit, I'm still confused. I don't get how there are 45-degree angles in (only) this one, or how the surface of the collapsing star goes spacelike in the other one (and where's the singularity there) etc... Wnt (talk) 23:36, 20 November 2015 (UTC)[reply]

Wormholes and event horizons don't directly have anything to do with one another. An event horizon is a one-way surface by definition, so a two-way traversable wormhole wouldn't have any event horizons by definition. A one-way traversable wormhole would, if you defined "event horizon" broadly enough. The two ends of the wormhole can be different "sheets" of spacetime, in which case neither one is really in the future of the other, or they can be in the same sheet, in which case the exit could be in the causal future of the entrance, or in the causal past (since this is unrealistic anyway), or in the "elsewhere" (neither causal past nor future).

The wormhole in the diagram with the two side-by-side diamonds is not traversable. No point in either diamond is in the causal future of any point in the other diamond, so you can't get to one from the other. It is called a wormhole because it's topologically a hole, not because there's any navigable connection. The causal future of a point in these diagrams is the upper triangle containing the point D in this picture, for example. In the charged/rotating diagram you still can't go between side-by-side sheets, but can go to any sheet that's higher up on the diagram.

"I don't get how there are 45-degree angles in (only) this one" – if you mean the vertical lines in Hawking's diagram, that's r=0. As I said, each point on these diagrams is a sphere (or an oblate-spheroid-like shape in the rotating case, I think). Hawking's diagram shows the spacetime before the hole forms and after it evaporates, at which times nothing special happens at the origin. But the diagram ends there anyway because there are no points with r<0. If you sent a light beam toward the origin it would "bounce off" that line.

The matter that forms the black hole doesn't really "become spacelike". Spacetime just collapses and goes singular on its own (with some help). -- BenRG (talk) 07:51, 21 November 2015 (UTC)[reply]

We do have an article on ER=EPR if anyone here understands the topic well enough to add to this, it would be good! Graeme Bartlett (talk) 23:12, 19 November 2015 (UTC)[reply]

There is no current article on this topic on Wikipedia and the information elsewhere online appears poor. It seems a thila is basically a submerged island close to the surface that supports reef and other marine habitats, but it isn't clear what actually defines a thila and how it differs from other similar marine environments. It would also be nice to know how they form geologically. Are they volcanoes that have not yet breached the surface? Old volcanoes that have eroded to below the surface, some other geological formation? If they are volcanic how do they differ from atolls? Thanks for any additional details you can provide on the topic. 166.176.187.231 (talk) 17:30, 18 November 2015 (UTC)[reply]

Thila is a Maldivean name for a small coral reef within the lagoonal part of an atoll, so just a local high point, pinnacle reef or patch reef are possible equivalent terms[12]. Mikenorton (talk) 21:21, 18 November 2015 (UTC)[reply]

See also File:CoralReef.svg. Mikenorton (talk) 21:47, 18 November 2015 (UTC)[reply]

This says what several ancient Mayan statues show, that indeed Maya had unusually large eyelids due to extra fold which gave them lazy look. What's the evolutionary or physiological reason behind that?--Brandmeister^talk 19:03, 18 November 2015 (UTC)[reply]

Just as a counterargument: how sure are you that the statues are supposed to be scrupulously accurate? I can pull artwork from a hundred other cultures where the art does not look like a photorealistic picture of the people in question. For the record, there are still seven million Mayan people still walking the earth. If you want to know what they look like, you can just, you know, look at them. We have photographs. --Jayron32 19:09, 18 November 2015 (UTC)[reply]

I don't know about these, but I recall it turned out that after many years of being perceived as simply white marble, Roman statues were found to have actually been painted with brilliant colors that had since worn away. The appearance of the eyes of any statue, therefore, needs to be considered skeptically since someone might have adorned the stone with material that is no longer present. Wnt (talk) 19:32, 18 November 2015 (UTC)[reply]

@Jayron32: It seems that commons:Category:Maya peoples shows basically the same, perhaps in ancient times it just was more pronounced. And we know, for example, that elongated skulls on Mayan statues are due to artificial cranial deformation. Brandmeister^talk 19:54, 18 November 2015 (UTC)[reply]

I looked at the references for the article you cited, and they don't appear to support the statements it makes about the Mayan appearance. I can't find any other scholarly source that supports them either. Possibly they're just obscure, but a measure of skepticism might be appropriate. Looie496 (talk) 20:22, 18 November 2015 (UTC)[reply]

Then what it's all about? If you look at multiple Mayan statues (including that of K'inich Janaab' Pakal), large eyelids are quite noticeable and it's not an individual feature. A local stylistic embellishment? Brandmeister^talk

At puberty in male humans, does the function of the testes generally begin before that of the prostate?

I'm curious because I recently remembered that it appeared to be that way for me. I'd been masturbating to orgasm for quite a while before puberty; when at the age of about eleven I started ejàculating it was viscous and stringy and so sticky I had to pull it off me, and it was several weeks before it became at all like a liquid. The other day I remembered this and it occurred to me that it could have been caused by a time difference in onset of function.

(Regular contributor here, using a throwaway account for privacy.) Throwaway1131 (talk) 01:41, 19 November 2015 (UTC)[reply]

Prostate#Development doesn't seem to contain much, but indicates that the prostate itself develops at around 9 weeks as an embryo. Wikipedia doesn't seem to have much to answer your questions, but perhaps if you researched more of the details of Gonadarche (the changes to gonads that occur during the early stages of puberty) you may find more about the mechanics necessary to answer your questions. --Jayron32 02:46, 19 November 2015 (UTC)[reply]

I think so, although not substantially so. Puberty begins when the brain, through the pituitary gland, signals the gonads to ramp up production of sex hormones. The elevated level of sex hormones then triggers all the other stuff. The article on the prostate notes that its function depends on levels of testosterone and its metabolite DHT. So it's not inconceivable that the prostate could be delayed in "turning on". Note that most of semen by volume is produced by the seminal vesicle, not the prostate or the testes. An important part of the prostate's secretions are enzymes that break down other components of the semen to make it flow more freely. My guess is that you're largely right, and your semen had a low level of prostate components, which meant it stayed viscous. --71.119.131.184 (talk) 19:47, 19 November 2015 (UTC)[reply]

How many times in Earth's 4.5-billion-year history did its magnetic poles switch places? When in the future will this happen again? GeoffreyT2000 (talk) 04:05, 19 November 2015 (UTC)[reply]

See Geomagnetic reversal. --Jayron32 04:08, 19 November 2015 (UTC)[reply]

Nutrition Facts is the label that comes with many packaged comestible items. What tools and knowledge do I need to compute the amount of nutrients by myself? Besides a calorimeter, what other tools do I need? How do I figure out the amount of sodium or sugars or vitamins or minerals? 140.254.70.25 (talk) 15:45, 19 November 2015 (UTC)[reply]

There are a number of different techniques for this, ranging from titrations, spectrophotometeric, atomic absorption spectroscopy, etc. It all depends on what specifically you are testing and what for. --OuroborosCobra (talk) 15:50, 19 November 2015 (UTC)[reply]

So, how do I make my own Nutrition Facts label? 140.254.70.25 (talk) 16:05, 19 November 2015 (UTC)[reply]

I agree with OuroborosCobra, with the addition that most food manufacturers just ask their suppliers for the nutritional facts of their ingredients, and then just use the weighted average of the ingredients that goes into one serving, or look it up from a database reference. Sending out samples to outside labs for a complete analysis is usually prohibitively expensive, especially for small companies. shoy (reactions) 16:07, 19 November 2015 (UTC)[reply]

Are you also asking about software and printers capable of printing an adhesive label ? StuRat (talk) 18:38, 19 November 2015 (UTC)[reply]

• I LOVE SUPER NOVAE FOR THEIR BEAUTIFUL LIGHT CELEBRATING WHEN THEY ARE APPEARING BRIGHTER AND THEIR SENDING OR OUR LIFE MATERIALS AND SPECIALLY THEIR PALPITATING PULSAR AS OUR HEARTSBold text

We know the black hole can not destroy its planet (as i approved last). But the supernova is different , what was happened for earth size and distance planet when the star was exploding even due at 1054  ?--Akbarmohammadzade (talk) 16:17, 19 November 2015 (UTC)[reply]

Any inner planets should be destroyed, but planets farther out (~hundreds of AU) could be ejected or find a new orbit around the remnant. [13] --Amble (talk) 16:39, 19 November 2015 (UTC)[reply]

So let's get some facts straight here. Firstly, it's called "The Crab Nebula" - but it was once a star that exploded into a supernova about 7,500 years ago. But because it's around 6,500 light years away, the light from the explosion didn't reach Earth until about 1,000 years ago - which is when Chinese and Islamic astronomers wrote about it. That explosion would have had to be incredibly violent. Even now, the debris from it is moving outwards at nearly 1,000 miles per second - or about three and a half million miles per hour! With all of that energy thrown out from the original star, it had insufficient energy left to hold it's massive weight against it's own gravity, and the core collapsed to become an incredibly dense neutron star - which is still out there.

OK - so what about planets. Firstly, not all stars have planets - so perhaps there weren't any. If there were, then the ones closest to the star would undoubtedly have been utterly destroyed by the initial explosion. In the vacuum of space, the material from the star would continue to move outwards in an expanding ball at millions of miles per hour - but as the size of that ball increased, the amount of material being thrown against any outer planets would rapidly diminish. But even a relatively low density gas moving at that incredible speed would rip away atmospheres of rocky planets and tear away at the surface of gas-giants. That initial pulse of energy would push on each planet and nudge them out of orbit somewhat.

Knowing exactly what would happen to each planet is a complicated thing. The size of the original star and the exact distance, mass and composition of each planet would factor into what happened - some might be torn to shreds, others pushed out of their natural near-circular orbits into crazy elliptical patterns that would send them out further and then have them fall back closer to the supernova's core. It's possible for a planet to wind up in a new, stable, orbit further out from the neutron star. I suppose it's also possible that enough force might be exerted on a planet for it gain escape velocity and to travel outwards with the debris cloud forever - but it could never go fast enough to avoid being continually bombarded with radiation and high speed particles from the star - so it's fate is never going to be good! For sure, any planet with an atmosphere would lose it instantly as the shock-wave passed it.

SteveBaker (talk) 15:53, 22 November 2015 (UTC)[reply]

^Topic ScienceApe (talk) 17:10, 19 November 2015 (UTC)[reply]

Only if your house is hermetically sealed (plants in a Controlled ecological life support system would have a measurable impact); your body is putting out an order of magnitude more carbon dioxide than a houseplant excretes oxygen, and you don't asphyxiate yourself by breathing. The Air changes per hour rate in a reasonably ventilated building is much higher than most people think. ‑ iridescent 17:17, 19 November 2015 (UTC)[reply]

Though they may some impact on the CO2 concentration. Ruslik_Zero 20:34, 19 November 2015 (UTC)[reply]

It takes roughly 20 trees to match the O₂ needs of one person [14]. So unless you are keeping a forest in your house, you probably aren't making much of a difference. Dragons flight (talk) 20:43, 19 November 2015 (UTC)[reply]

Does an 'electric dimmer' help reducing the cost of electric bill? -- Space Ghost (talk) 18:26, 19 November 2015 (UTC)[reply]

Incrementally, maybe. But your average major appliance is going to pull way more juice than that. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:31, 19 November 2015 (UTC)[reply]

If you use it at a dimmer setting than you otherwise would, then yes. Some caveats:

1) You should have CFL or LED bulbs to save energy, and only certain ones work with a dimmer.

2) You could also just put a lower wattage bulb in, if you never need full brightness.

3) There were some very old dimmers that just wasted the "unused" electricity while generating heat. I doubt if you have any of those.

4) Dimmers often have rather limited wattage they can handle. Probably not an issue unless you are using halogen lights.

5) Dimmers tend to wear out more quickly than regular light switches. StuRat (talk) 18:35, 19 November 2015 (UTC)[reply]

Points noted, but, I was watching a programme made by a guy who hosted Top Gear show, he was showing/proving disturbances occurring when using dimmers. Basically, if you use dimmers than it disturbs the flow of electricity, and apparently, its not good to use one... Anyway, I'll bear both of your statements and the Top Gear guy's information in mind, I hope you guys do too, recall before fiddling with electrical stuff. Thank you. -- Space Ghost (talk) 18:53, 19 November 2015 (UTC)[reply]

I can think of few people whose opinions I'd take less seriously on electrical engineering than Jeremy Clarkson; every electrical appliance will "disturb the flow of electricity", since converting electric flow into light, heat or motion is the entire point. Of course a dimmer switch is going to "disturb the flow of electricity", since that's the entire point of a TRIAC; while (very) old dimmer switches worked by resistance, which as StuRat correctly points out just dissipated "spare" energy as heat, the thyristor in a modern dimmer switch works by partially interrupting the alternating current (in effect interrupting the flow of electricity hundreds of times per second to cut down the flow to the bulb). As Baseball Bugs says, the energy saved will be minimal as a lightbulb really doesn't use much power to begin with unless you're running an anti-aircraft searchlight; your best ways to save power around the home is to turn down the heating/air conditioning, and replace your washing machine. ‑ iridescent 21:24, 19 November 2015 (UTC)[reply]

(adding) What you don't want to do with a dimmer is use it on fluorescent bulb (usually marketed as "low energy bulbs" or Compact fluorescent lamp bulbs) that isn't explicitly marked as safe to use with them, unless you have a particular desire to see your house go up in flames. ‑ iridescent 21:36, 19 November 2015 (UTC)[reply]

iridescent, I think it was probably James May, not Jeremy Clarkson. Rojomoke (talk) 21:38, 19 November 2015 (UTC)[reply]

A bad TRIAC can leak noise into the power line, much to the chagrin of guitar players (especially those with noise-sensitive single coil guitar pickups). Here's pickup maker Seymore Duncan's thoughts on mitigations for that: [15] (although there are several other causes for hum on single-coil pickups). If I understand the mechanism properly, the noisy TRIAC leaks junk into the building wiring, which acts as an antenna broadcasting that, which the single-coil pickup receives (single-coil pickups are great at detecting all kinds of RF and magnetic garbage, including radios, phones, and CRT TVs) - the active parts of a guitar amp (which are coupled to the pickup coil) are magnetically isolated from the mains (by a transformer), so I think that the dimmer hum doesn't get in through the amp's mains connection. Guitars with humbuckers are much less sensitive to dimmer noise. -- Finlay McWalterᚠTalk 00:20, 20 November 2015 (UTC)[reply]

I understand what you all have stated, I do understand about the disturbance too, its just that it was shown in a way that it is completely bad to use dimmers... Thank you all. Regards. -- Space Ghost (talk) 19:10, 20 November 2015 (UTC)[reply]

The fancy term for these "disturbances" is harmonics. These are an issue in electrical power engineering, but if you're not being billed based on power factor (which you aren't if you're a standard residential customer) they're the power company's problem, not yours, unless as mentioned above you're an electric guitar player or doing something else sensitive to electrical noise. And anything that isn't a perfect linear load generates harmonics, including motors and the switched-mode power supplies that modern electronics use for mains power. As far as saving power goes, I personally don't see the point of using dimmers. Using CFLs or LED lights will save way more power so it's something you should be doing already. Aside from that, just turn off lights when you don't need them. As others mentioned, a typical home's energy use mostly goes to appliances and climate control, so focus on those to save energy. --71.119.131.184 (talk) 20:10, 20 November 2015 (UTC)[reply]

I understand. I'm environmental friendly too, except on/for some helpless lifestyle things. Regards -- Space Ghost (talk) 05:43, 21 November 2015 (UTC)[reply]

Dimmers generate a duty cycle from the AC of the power grid. LEDs lamps, transformers and LED based bulbs connected to a dimmer required to be specified for this environment as "dimmable". These light-weight transformers athe switched-mode power supplies, couppling their reference output to the input and have recifiers installed that can handle the dimmers AC wave form. LEDs are also feed from current pulses substituting and adequate constant current to fit the LED's specification. Those pulsewidhs might interfer with the dimmer's output causing a permanent damage when components are not designed for such operation. Note dimmers may differ in cutting on or off the sine wave. Rectiviers tolerate the cut off more easyly, than the turn on to pte peak voltage to the AC which the inexpensive bulb dimmers do by their phase shifting circuit. --Hans Haase (有问题吗) 12:26, 21 November 2015 (UTC)[reply]

Peeps, I bought this pen size USB led light today, it consist of 10 led light or so, I also have a universal plug with a USB port, I wonder if I could/should plug it with the universal plug, use it instead of the fluorescent bulb that I have; it's powerful enough. I just need an assurance in, whether its better or not energy saving wise cause its connected with a plug into a socket. If not, then I'll use it with my PC port. -- Space Ghost (talk) 21:38, 21 November 2015 (UTC)[reply]

My guess is that if you need to have the PC on anyway, then plug the light into that - but if you have to turn on the PC just to power your light, then that's likely to be a collossal waste of energy. However, much depends on the computer's power supply...a desktop PC would offer different trade-offs than a laptop. But to be honest, the cost of running the LED light is so tiny compared to running (say) your refrigerator, it hardly matters. SteveBaker (talk) 03:57, 22 November 2015 (UTC)[reply]

Your pen-size USB LED shouldn't consume more than 2.5 watts (500 milliAmps at 5 volts) - because that's all that a USB 1.0 or 2.0 port is guaranteed to deliver - but I doubt that it uses even a fraction of that. A small PC will need at least 100 watts - probably much more if it's a powerful one with fancy graphics and a high speed multi-core CPU. My PC has an 800 watt supply.

So adding the LED light probably adds considerably less that 1% to the PC's power requirements.

SteveBaker (talk) 04:27, 22 November 2015 (UTC)[reply]

I understand that when common salt is dissolved in water it dissociates into separate sodium and chloride ions. So when we taste a salty liquid, are we tasting the sodium, the chloride, or a combination of both? --rossb (talk) 00:02, 20 November 2015 (UTC)[reply]

Salt substitutes (potassium chloride) and calcium chloride taste salty, but not identical. Calcium chloride is chalky and salty at the same time. Sagittarian Milky Way (talk) 00:09, 20 November 2015 (UTC)[reply]

Warning: Do not put large amounts of calcium chloride in the mouth. The article says too much gets hot enough to cause burns. Sagittarian Milky Way (talk) 00:13, 20 November 2015 (UTC)[reply]

See Taste#Saltiness. The direct answer is "the sodium ion". --Jayron32 01:13, 20 November 2015 (UTC)[reply]

I confirmed thenardite (sodium sulfate) has a salty taste similar to halite. [16] Wnt (talk) 23:44, 20 November 2015 (UTC)[reply]

Does a candle pot heater heat a room significantly (that is, you feel it)? A candle pot heater is a DIY heater that is built with a clay pot (or a set of them stapled) upside-down, with a candle (or more) inside it. Some people claim that "Terracotta pots absorb the thermal energy of the candles and convert it into radiant space heat." and "heater works by trapping and concentrating the heat that would normally just rise to the ceiling and quickly dissipate in the surrounding air."

Would the heat of this heater be transmitted differently from the heat of a candle alone? I am just curious about it, but do not intend to build one. There seem to be some safety issues with this thing.--Denidi (talk) 00:56, 20 November 2015 (UTC)[reply]

There's a very detailed discussion about these at stack exchange. -- Finlay McWalterᚠTalk 01:04, 20 November 2015 (UTC)[reply]

I wonder whether it has an article with another name here in Wikipedia.--Denidi (talk) 01:13, 20 November 2015 (UTC)[reply]

The nearest I can find is a Masonry heater, which is basically the candle/terracotta pot heater but for realz. It is functionally the same operation (a burning source first heats ceramic, which then heats the room radiatively). --Jayron32 02:01, 20 November 2015 (UTC)[reply]

Yes, the British used flower-pot heaters during the second world war to heat their Anderson shelters. In the scouts we used them too (but that was mainly because Akela somehow managed to take us camping on on the cold and wettest weekends). As the OP says, heat from a candle just goes up but in a flower-pot heater, it gets trapped and radiates. It might seem surprising but considering a average one Candela candle produces about 80 watts of heat, three produces not much short of a ¼ of a kilowatt. So, to answerer OP's question – Yes, you do feel the warmth. The OP may not be intending to make one but here is some easy to follow destructions in case he changes his mind: Candle Powered Air Heater. This came in handy about a decade ago when we had a long winter power cut, which meant the electric central heating pump would not run. Unfortunately, we only had some scented candles which meant the place smelt like some oriental whore house – but at least we were warm.--Aspro (talk) 22:10, 20 November 2015 (UTC)[reply]

Ahh, the aroma of oriental whorehouses... Alansplodge (talk) 02:13, 22 November 2015 (UTC)[reply]

A typical space heater is 1500 watts, so even the three candle 240 watt setup is less than 1/6th of that. That would only warm a small room slightly. StuRat (talk) 08:54, 21 November 2015 (UTC)[reply]

Comment: Both Anderson shelters and tents are very small spaces. I reckon I could fit nine into my lounge (three rows of three) and being lower in hight than the ceiling, they would take up less volume too. So that's about a tenth of what a space heater is expected to warm . Remember too, that a big part of the reason one feels cold in this situation -is that you too- are radiating heat but little heat is being radiated back. It is a bit like putting ones finger close to an ice-lolly. Ones finger on that side feel colder but we know cold does not radiate. It is the diminution of radiated heat blocked by by the ice lolly that gives the subjective imprecision of radiated cold. Flower-pot heaters work just fine in the right environment. Also, they don't produce carbon monoxide (bad in a small space). I entourage the OP to build one, just in case he should need one – but please, do hold a stock of non-scented candles for such emergenticies.--Aspro (talk) 16:21, 22 November 2015 (UTC)[reply]

Seen today in Edgerton, Ohio on the side of a slowly-moving rail car:

Hammering on side of car will contaminate product.

What kind of product could this be, and how would it be contaminable? The car in question looked like a grain hopper, but I'm not sure that it wasn't something else. Google reveals nothing except for a few pages (example) commenting on this kind of inscription. This page doesn't seem to make much sense, because aren't grain hoppers emptied by gravity through trapdoors in the bottom of the car? Nyttend (talk) 01:33, 20 November 2015 (UTC)[reply]

I suppose hammering could damage some coating, which could contaminate the product. --Denidi (talk) 01:42, 20 November 2015 (UTC)[reply]

• Here's a quote from a company that leases hopper cars:

Car body damage caused by a derailment, sideswiping or hammering of side sheets can cause failure of the interior lining and subsequent product contamination from chips or flakes of lining material.

It may have been a pressurized hopper car, which uses air pressure rather than gravity to dispense the product. The company talks about transporting plastic resins, which are very prone to contamination (since even a tiny amount could change the resin's properties or gum up the machinery). Smurrayinchester 08:44, 20 November 2015 (UTC)[reply]

I mean according to those that count 22 parts (rather than 28) 92.249.70.153 (talk) 02:54, 20 November 2015 (UTC)[reply]

The two Parietal bones are the largest bones in the skull. Of the 22 named in the Wikipedia article Human skull, the smallest is the Vomer, a small portion of the nasal septum. --Jayron32 03:05, 20 November 2015 (UTC)[reply]

Thank you. In our article about "lacrimal" bone, I saw that the lacrimal bone is the smallest bone. What's true? 92.249.70.153 (talk) 03:23, 20 November 2015 (UTC)[reply]

Sorry, yes, I believe you're correct. I misremembered which bone in the nose was the smallest. It looks like each of the two lacrimal bones are smaller than the vomer. FWIW, if you consider the ears to be part of the skull, the stapes is much smaller than any of those, but that is not one of the 22 listed at the Human skull article. --Jayron32 04:03, 20 November 2015 (UTC)[reply]

About the largest bone I heard about two: Frontal and occipital, and this is the first time that I hear about the parietal. Someone has a relabel source about this topic? (I have Gray's anatomy book and Moor anatomy book and I didn't find) 92.249.70.153 (talk) 05:56, 20 November 2015 (UTC)[reply]

The Parietal bones form the largest part of the top and sides of the cranium, The parietal bones are two of the largest bones of the skull --Jayron32 13:50, 20 November 2015 (UTC)[reply]

Are the parietals always the largest, even across species? This might refer only to humans. DRosenbach ^{(Talk | Contribs)} 15:45, 20 November 2015 (UTC)[reply]

Context established by the OP "...22 parts (rather than 28)..." has already made it clear we're talking about the human skull. --Jayron32 16:04, 20 November 2015 (UTC)[reply]

Oddly enough, we just had this question on the science desk a little while ago. The material above notwithstanding, our article on mandible says it is the most massive bone "in the face" (which is obviously not synonymous with skull). The frontal and parietal bones are wide, but quite thin (the frontal bones appears thick at the front, but is mostly hollow there to accommodate the frontal sinus whereas the jawbone, especially in males, is much more robust. 99.235.223.170 (talk) 13:47, 21 November 2015 (UTC)[reply]

I was changing the water in my fish tank last night, and while removing water from the tank via a pump action siphon tube (starts off by hand pumping, but then runs by itself), I noticed that I was able to have the water exit the tube up to 3 inches higher than the water enter the tube inside the tank. So it got me wondering why we're not able to create perpetual motion machines using such technology. Sure, the amount of power we could generate with a gallon of water dropping 3 inches per, I don't know, a minute, is not much. But couldn't this be built on such a tremendous scale, and by having a million tubes set up like this, couldn't it then generate endless power? Obviously I'm missing something, because I'm no physicist and I'm sure this would have been something discovered a while ago. But just curious as to what the issue is here. Thanks! DRosenbach ^{(Talk | Contribs)} 15:43, 20 November 2015 (UTC)[reply]

Friction is a mean bitch. --Jayron32 16:05, 20 November 2015 (UTC)[reply]

Rule #1: If you think you have perpetual motion - you don't.

With a syphon, the water can't possibly exit higher than the surface of the water from which it's fed. It doesn't matter where the BOTTOM of the intake tube is. Lower the water level until it's below the height of the output of the syphon and it stops working - no matter how deep the input end is beneath the water. The syphon doesn't do anything magical that simply drilling a hole in the side of the tank at the same height wouldn't have done. Hence, you don't have perpetual motion here and you can't gain any 'free' energy.

So there is always an error in your assumptions. The only (somewhat) interesting thing is figuring out where you went wrong.

SteveBaker (talk) 16:59, 20 November 2015 (UTC)[reply]

I should be completing mine within the next few days. :-) --Modocc (talk) 17:21, 20 November 2015 (UTC)[reply]

Such a device was designed by Robert Boyle in 1660, so the idea is not original. Tevildo (talk) 19:18, 20 November 2015 (UTC)[reply]

Yep, and for further info we have articles about perpetual motion and thermodynamics. And I may as well post here in a couple a days to let you know whether my own twist on a 2nd thermodynamic law violating machine actually works or not.. -Modocc (talk) 19:38, 20 November 2015 (UTC)[reply]

(EC)You need to ignore the submerged portion of the tube because its irrelevant. Next time you siphon you should notice that the flow stops when you raise the free end of the tube higher than the level of the water in the tank so only the water's gravitational potential can be tapped from the setup. -Modocc (talk) 17:16, 20 November 2015 (UTC)[reply]

It is relevant, since once the water level drops below the submerged portion, the process stops. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:55, 21 November 2015 (UTC)[reply]

Being submerged certainly matters, but I didn't think I be misunderstood and needed to state the obvious and said only to ignore the submerged portion, that is with a depth greater than 0. --Modocc (talk) 17:25, 21 November 2015 (UTC)[reply]

The above comments are true, but I'll go a step further: consider capillary action, where the water is drawn above the surface of the body of water the tube is placed into. Well, the problem is, the force of attraction between water and wetted surface that brings the water into the tube ... also resists it being removed from it. So you can draw water up but it won't drip out from that height. You (or plants) can manipulate the system via transpiration, but that relies on a difference in humidity that is gradually being used up to power the system, essentially a sort of "wind power" you might say.

The bottom line is path independence. However you get to a region of low potential energy, you are always going to have trouble going back up again. Wnt (talk) 18:05, 20 November 2015 (UTC)[reply]

Notwithstanding all the assertions by learned Users here, it is possible to create a device to which water is added, and then the water flows to a height above the level of the water pool! One example is known as Heron's fountain. It provides a useful exercise to explain why it isn't perpetual motion. Dolphin (t) 06:15, 21 November 2015 (UTC)[reply]

It looks like it uses the energy produced from lowering most of the water to raise a small portion of it. I suppose you could also do that at any hydroelectric dam, by using the power generated to raise the level of a small portion of that water. StuRat (talk) 06:30, 21 November 2015 (UTC)[reply]

Stu, did you mean to, and forget to, link to Pumped-storage hydroelectricity? --Jayron32 06:35, 21 November 2015 (UTC)[reply]

To be clear - we're talking here about a simple syphon. In that case, the water that emerges from the syphon can't end up higher than the surface of the water in the reservoir supplying it. Nobody is saying that you can't build some other kind of contraption (such as Heron's fountain) which is powered by the gravitational potential energy of water in one place to raise a smaller quantity of water to a greater elevation in some other place. Clearly that's possible so long as the net energy of the system didn't increase as a result. That restriction means that you can't extract 'free' energy from such contraptions, and because of friction, they'll always run down eventually.

Our OP's surprise lies in the fact that the height of the inlet side of the siphon can be lower than the outlet...but it turns out that this doesn't matter. What matters is the relative height of the surface of the water on the inlet and outlet sides. SteveBaker (talk) 13:29, 21 November 2015 (UTC)[reply]

Thermodynamics explained in four simple rules (by C. P. Snow):

Zeroth - You must play the game.

First - You can't win.

Second - You can't break even.

Third - You can't quit the game.

Roger (Dodger67) (talk) 08:36, 22 November 2015 (UTC)[reply]

In a metal, electrical conduction is said to be provided by electrons flying about within the metal, not bound to any one atom or being an inter-atom bond. Only some electrons do this, I think, certainly not all electrons each atom could contribute. In TYPICAL pure metals, what is the ratio of the number of conduction electrons to the number of atoms? For COMMON alloys? 124.178.79.219 (talk) 02:53, 21 November 2015 (UTC)[reply]

You'll want to be researching concepts like Fermi level and Electronic band structure and Metallic bonding and band gap. Delocalized electrons in metals are located in the conduction band. --Jayron32 04:51, 21 November 2015 (UTC)[reply]

And if I could make sense of those articles, I'd probably have a PhD and wouldn't need to ask such a simple question! So how many electrons does each atom TYPICALLY contribute to the conduction band? 1.122.54.74 (talk) 06:01, 21 November 2015 (UTC)[reply]

It depends on the metal in question, the temperature of the metal, and probably many other factors. It's not as simple as you seem to require to answer your question... --Jayron32 06:08, 21 November 2015 (UTC)[reply]

According to Electrical_resistivity_and_conductivity#In_metals only the outer shell electrons are delocalised. The number therefore depends on which metal(s) you have and their electron structures. For example, copper has a single outer electron so the ratio is 1:1. I'm sure someone will be along to tell me it's not quite as simple as that.--Heron (talk) 09:33, 21 November 2015 (UTC)[reply]

Well Jayron, if it depends on the metal, in what way? If that is complex, what about some examples? If it depends on temperature, to what degree, TYPICALLY? What is the ratio at around normal temperatures? Is it linear with temperature? A power relationship? 1.122.126.61 (talk) 09:54, 21 November 2015 (UTC)[reply]

I thought you were having trouble understanding such things? Either this explanation would make sense to you, and you'll have your answer, or it won't and you'll come back here asking questions and expecting simple answers which we can't give because they don't exist. The simplest answer (and the very wrong one) is that each atom in a metal contributes one electron to the sea of electrons. The more complex answer (and more correct) answer is given by that paper I linked to, which discusses modeling delocalized electrons as a fermion gas to calculate their density in a given material. --Jayron32 16:08, 21 November 2015 (UTC)[reply]

Jayron, this isn't helpful. The website you linked states in the first line that each atom contributes one conduction electron. What the rest of it says is beyond me - it certainly doesn't give any usable result such as "pure copper at room temperature has 0.7 electrons per atom available for electrical conduction." or whatever the ratio might happen to be. Surely, no matter how what level of math is required to work it out, the result is dependent on only two things - the material and the temperature.

If somebody asked you for the electrical resistivity of typical metals, would you point them to a web page that lists typical values for copper, steel and the like and perhaps state that it increases about 0.4% for each degree temperature (or whatever it does), which would be helpful, or would you give them some book on Ph.D level physics that covers the theory of why, and tell them if they cannot understand that then they are not entitled to ask the question? 1.122.126.61 (talk) 16:44, 21 November 2015 (UTC)[reply]

If you wanted to know the electrical resistivity of typical metals, you should have asked the first time. Here is a table of them. --Jayron32 20:02, 21 November 2015 (UTC)[reply]

I don't, and did not, want to know electrical resistivity. I want to know: in some pure metals, what is the TYPICAL ratio of the number of conduction electrons to the number of atoms? At a convenient temperature(s) if varies significantly. And for a few COMMON alloys would be good.

If you don't have any idea, leave it for someone else, don't be a smartarse. If you can do the math, perhaps you could explain it and/or draw some conclusions. 124.178.132.112 (talk) 01:34, 22 November 2015 (UTC)[reply]

By 'conduction electrons', I'm assuming you mean 'free electrons'. That is, the number of those which circulate freely when no potential difference (voltage) exists to drive electrons along and form a current. As I understand it, when a current is made to flow, electrons that are weakly held in orbit detach and join the free electrons in forming the current. Is my understanding of your terminology correct? Akld guy (talk) 01:54, 22 November 2015 (UTC)[reply]

Yes, your understanding of my terminology is indeed correct. I mean the electrons that fly about within the metal like molecules do in a gas, due to having kinetic energy.124.178.132.112 (talk) 02:30, 22 November 2015 (UTC)[reply]

(edit conflict)this has some additional calculations, and has a simpler method of approximating the free electron density. The equation is basically N=(Avogadro's number*density)/molar mass. So, for copper, the value would be(6.02E23 * 8.96)/63.55 = 8.45E22 electrons per cubic centimeter. --Jayron32 02:10, 22 November 2015 (UTC)[reply]

Also found, on the same page here is a place to enter data in yourself to calculate free electron density, if all you know is the Fermi level of the material. this page lists the fermi level of copper as 7.00 electron volts, by plugging that in to the calculation give 0.841E29 electrons/cubic meter, which is 8.41E22 electrons per cubic centimeter, which is damned close to the approximation given above using only the molar mass and density. --Jayron32 02:26, 22 November 2015 (UTC)[reply]

Well, Jayron, the number of ATOMS per unit volume is also Avogrado x density / molar mass. Even I with just a junior high education knows that. So, according to your post just above, the ratio of free flying electrons to atoms is 1:1. But in your ealier post, you said "The simplest answer (AND THE VERY WRONG ONE) is that each atom in a metal contributes ONE electron to the sea of electrons." You also said it depends on temperature. Please go away Jayron. I'm hoping someone who understands this topic will answer. 124.178.132.112 (talk) 03:00, 22 November 2015 (UTC)[reply]

Thank you. I wanted to make sure that your terminology was understood for those who might be inclined to answer. Nobody can answer the question off the top of his/her head, since it depends on the metal, its purity, and its temperature. There may be other factors. Speaking as a former telecommunications engineer and with more than 50 years of experience as an electronics enthusiast, I can state that your question has no practical application whatsoever. You are almost certainly trying to get unpaid research assistance in the writing of a thesis or textbook. Others may wish to do unpaid research on your behalf. I do not. Akld guy (talk) 04:14, 22 November 2015 (UTC)[reply]

Writing a textbook or thesis? I wish! Not with my junior high education and career in cabinet-making. I'm just trying to get some understanding of solid state physics. If you can't help, you are under no obligation to do so. Just leave it for others. 124.178.132.112 (talk) 04:45, 22 November 2015 (UTC)[reply]

Cabinet-making? I always thought you were an engineer. At least, isn't that what you told us in the past? Nil Einne (talk) 05:40, 22 November 2015 (UTC)[reply]

Is this a help desk or a nut house? What past, exactly? I've asked a couple of questions here in the last few months. Haven't mentioned engineering in any of them. 121.221.73.213 (talk) 07:13, 22 November 2015 (UTC)[reply]

I was referring to the stuff in 2012 - 2013. Also this isn't a help desk, it's a reference desk (note, not an answer desk either). If you want the help desk, try WP:Help Desk but that isn't the place for questions like this. Nil Einne (talk) 08:47, 22 November 2015 (UTC)[reply]

Help desk, reference desk, answer desk, whatever. I have no idea what you are on about re 2012 or 2013. I didn't discover this page until about 6 months ago. This is the Science Desk, and my question is a science question. People ask questions because they want help. Clearly this site was set up so people could get ANSWERS to questions. There is no help in all in this thread, except from Heron. Certainly not in whatever mysterious thing happened in 2012. 121.221.73.213 (talk) 10:12, 22 November 2015 (UTC)[reply]

Actually this was set up primarily as a reference desk, which will often hopefully help people get answers to questions, but ultimately it's intended to act as a reference desk and not a place for people to get answers to questions. Anyway if you don't understand why this is different from the WP:help desk, and in particular, why it's important that this is a reference desk and not an answer desk, you're probably at the wrong place. Try Yahoo Answers or something. As for your claim about not being WickWack, perhaps you're telling the truth. Your attitude here makes me doubt that though, but either way you're not likely to get much help here, or anywhere else, when you yell at everyone who answers. Nil Einne (talk) 14:51, 22 November 2015 (UTC)[reply]

What claim? Where? Who or what WickWack is, I have no idea. I made no claim to be not WickWack - until now I had never heard of him/her. I do so claim now though. So your response is quite odd. As for the rest of it, this whole page has lots of questions, which have attracted many ANSWERS. Answers I have recieved in response to other questions have been very helpful. But the responses here have been essentially "Read this advanced Ph.D level text. If you can't understand that, you are not entitled to ask your question." And "this is of no practical application." Who says? Why should it matter? If you think these are useful approaches, you deserve to be "yelled at", because they are unhelpful. They add no value. And whatever happened in 2012 has nothing to do with my question.

The solution to this is obvious: If you & Jayron see a question on a topic you don't understand, don't respond. Don't waste your time. Leave it. Someone else who does understand the topic or has a good hint may well then respond. 121.221.73.213 (talk) 15:59, 22 November 2015 (UTC)[reply]

I know two caves: nasal cave and orbital cave. Is there more? 92.249.70.153 (talk) 03:19, 21 November 2015 (UTC)[reply]

Do you mean cavity rather than cave? The skull has a nasal cavity, orbital cavity and sinus cavity. --Jayron32 04:48, 21 November 2015 (UTC)[reply]

I found also middle ear cavity as well as oral cavity and carnial cavity. Is there a difference between sinuses to the cavities? 92.249.70.153 (talk) 06:27, 21 November 2015 (UTC)[reply]

There's also the cranial cavity - containing the brain. Roger (Dodger67) (talk) 16:39, 22 November 2015 (UTC)[reply]

As a result of chemical or physical reactions when heating/cooking foods: 1.will it make certain fruits(example plums,durian,banana,apple) to change from sour to sweet or vice –versa? 2.will it help to make foods that has gone slightly bad to be safer for eating? Please also state the reasons for your answers.

This sounds an awful lot like homework. Why not try answering the questions yourself and then coming back here if you get stuck? You could even post your answer here and we'll likely vet it for you. In particular, think about what makes something sweet or sour and about how food is made more safe for eating. Is cooking used to accomplish either of these things? 99.235.223.170 (talk) 19:59, 21 November 2015 (UTC)[reply]

Judging by [17], Google aerial view at 41°34′24″N 84°2′35″W / 41.57333°N 84.04306°W / 41.57333; -84.04306, and my picture, what kind of facility is the North Star BlueScope Steel mill near Delta, Ohio? Trying to figure out which subcategories of Commons:Category:Steel production I should use for the image. Nyttend (talk) 00:05, 22 November 2015 (UTC)[reply]

"Since 1997, North Star BlueScope Steel LLC has been providing hot rolled bands...". They also have furnaces (including an electric arc furnace) that input pig iron and other raw materials. That would make it a refinery, a foundry, and a rolling mill: it's a facility that takes in ore and raw material, melts it and mixes it to produce steel, and finally hot rolls the output steel to produce coiled sheet metal. Nimur (talk) 02:02, 22 November 2015 (UTC)[reply]

Perty much every year I buy ornamental squash / pumpkins in mid-october as gifts. They are solid, hard, weigh only a few ounces each, and seem to be wax covered. Nevertheless, the ones I buy my mother are almost always mold-ridden by Thanksgiving. (I give the others away to store clerks I deal with regularly, they don't report on their demise.) Is there some way to preserve them by washing or heating or the like? Thanks. μηδείς (talk) 00:49, 22 November 2015 (UTC)[reply]

Regular washes in a dilute bleach/water solution (like a capful of Clorox bleach in a kitchen sink full of water)? When we buy fruit we do that to make it last longer, at my estimate we can about double the shelf-life of a 3 pound bag of mandarin oranges that way. --Jayron32 01:29, 22 November 2015 (UTC)[reply]

The enemy here is moisture. If the skin is not damaged and no part of the squash is exposed to constant moisture, it should last months without getting moldy. Looie496 (talk) 13:05, 22 November 2015 (UTC)[reply]

Location (location, location) is probably the key here. Just move your mom to Canada and the pumpkins will easily last from mid-October to Thanksgiving! Okay, more seriously, only getting a month on squash seems awfully short. Per Looie, moisture is the problem, so the place of storage is going to be key; keeping them in a bowl in the kitchen is a high-risk activity. Moisture from cooking and dishwashing will inundate the place (and roll out an invite for mold). You may also want to make sure that she's not sticking it in a bowl with fruit, such as apples or bananas. They outgas ethylene quite vigorously, aging the squash prematurely. 99.235.223.170 (talk) 13:28, 22 November 2015 (UTC)[reply]

Can anyone describe what it would feel like, for an average human, if one were standing at the equator on a planet the size of Earth, but this planet is rotating on its axis many orders of magnitude faster than Earth's rotation? Would one 'fly off into space'? Would one get squashed by inertial forces? Would there be any physical effects at all? Or would the person just see the stars whizzing by really fast? -- œ^™ 06:43, 22 November 2015 (UTC)[reply]

If Earth were to spin at more than about 18 times its present rate, nothing on the equator would stay down. I don't know what you mean by "squashed by inertial forces". —Tamfang (talk) 08:01, 22 November 2015 (UTC)[reply]

Actually the higher centrifugal force at the equator causes the spheroid to deform - expanding at the equator (increased oblateness) to maintain hydrostatic equilibrium. -- Roger (Dodger67) (talk) 08:48, 22 November 2015 (UTC)[reply]

Yes, exactly. The Earth shouldn't be considered as a solid 'thing' - it's a relatively loose collection of stuff held together by gravity. If the rotational speed were to increase, the particles at the equator that are experiencing more centrifugal force will move outwards somewhat and material from the poles would move inwards a little to fill the void. The earth would go from being a perfect sphere to becoming squashed a little. In fact, this has already happened and the earth is about 44 kilometers wider than it is tall.

So with increased spin, the shape of the earth would flatten more and more. The experience for someone standing at the equator would indeed feel like a reduction in gravity...and that's true right now. If you currently weigh 100lbs at the north pole, you'd only weigh 99.65lbs at the equator.

But even one order of magnitude increase in spin rate would be catastrophic...the shape of the planet would change drastically...and much more than that would cause the whole thing to break apart - there would be catastrophic consequences long before a person would fly off of the surface. SteveBaker (talk) 16:09, 22 November 2015 (UTC)[reply]

The increase in spin speed might make you feel lighter, but the increased mass of rock underfoot would increase gravity, right? Gravity varies locally depending on what's underfoot - surely a more greatly deformed earth would affect that as well? 99.235.223.170 (talk) 16:32, 22 November 2015 (UTC)[reply]

That's why I linked hydrostatic equilibrium. Roger (Dodger67) (talk) 16:36, 22 November 2015 (UTC)[reply]

Steve's 99.65 lbs. isn't exactly right. You feel lighter at the equator for two reasons. One is the direct effect of the centrifugal force (i.e. centripetal acceleration of the Earth away from you). This is given by v²/r and works out to about 0.35% of 1 g-force, so I assume that's what Steve had in mind. But the other reason is because you are farther from the center of the Earth. If the Earth was a sphere, the force of gravity would be proportional to 1/r² and you would be about 0.71% lighter for that reason, compared to the poles; but the whole point of this calculation is that the Earth is not a sphere, and so you will feel additional weight due to the equatorial bulge, reducing the effect I just described. Perhaps someone can cite a reference that provides the correct value. --70.49.170.168 (talk) 16:51, 22 November 2015 (UTC)[reply]

See headline.

There are many cats orbiting the sun. We don't know what their names are, only what their owners choose to call them. SteveBaker (talk) 15:58, 22 November 2015 (UTC)[reply]

Cats don't have owners, they have slaves. Roger (Dodger67) (talk) 16:35, 22 November 2015 (UTC)[reply]

And anyway, the naming of cats is a difficult matter; it isn't just one of your holiday games. --70.49.170.168 (talk) 16:53, 22 November 2015 (UTC)[reply]

To get back to the OP's question, the technical term is Small Solar System body - meteoroid is also a possibility, although we'd have to use the definition of "metal" as "anything other than hydrogen or helium" for this particular case. See also Asteroid#Terminology. Tevildo (talk) 16:40, 22 November 2015 (UTC)[reply]