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July 30

Domesticated Hedgehog

Is there a scientific difference between a hedgehog and a domesticated hedgehog as there is between wolves and dogs or lions and cats? — Preceding unsigned comment added by 68.115.240.26 (talk) 01:49, 30 July 2013 (UTC)

Have a look at hedgehog, then domestication, then domesticated hedgehog. Those should cover the basics. Despite the name, my impression that the domesticated hedgehogs are not very domestic (i.e. less time under artificial selection, less derived traits), in comparison to the case of dogs derived from wild canines. SemanticMantis (talk) 03:48, 30 July 2013 (UTC)

As for your other examples, wolves and dogs now appear to be the same species, so that's a reasonable comparison, but lions and (house)cats are not the same species at all and cats certainly are not domesticated lions, but rather cats are domesticated African wildcats. StuRat (talk) 06:14, 30 July 2013 (UTC)

Wierdly enough though the dog and the wolf are (as of 1993) considered the same species and cats and the African wildcat are not even though dogs were domesticated much earlier. But I don't think that represents a higher amount of genetic change. And sorting out the genus and species of the smaller members of Felinae (like the wildcats) gets ugly.Naraht (talk) 13:33, 30 July 2013 (UTC)

I had never heard of a domesticated hedgehog until a few seconds ago. My only comment is that according to our article, it is a hybrid of two separate species and therefore different to any wild hedgehog. Is a mule different to a horse? Yes. Alansplodge (talk) 22:58, 30 July 2013 (UTC)

Feeling pain in a dream

I just woke up from a long nightmare. The last part of the dream was someone digging their hands into my chest, as if they were trying to murder me. The odd part was that I ran away from the person in my dream, but then I saw myself laying down where I was in real life right after, in my dream. The person was right there, which is when they dug their hands into my chest. An even more odd thing is that I felt the pain and woke up from it. I am very shaken and I don't think that I can get back to sleep which is understandable, considering I felt like I was being murdered. Has there been any reports of people feeling pain in their dreams? Please don't tell me that it can't happen, I felt the intense pain in my chest, in all of the correct spots. SL93 (talk) 08:38, 30 July 2013 (UTC)

When a person is in REM sleep brain activity is high and it will often interpret a physical stimulus and make it a part of a dream. This is such a common experience that it has become a film Cliché. Wikipedia has an article about Nightmare but the Ref. Desk will not interpret dreams. DreadRed (talk) 09:32, 30 July 2013 (UTC)

I wasn't asking for my dream to be interpreted. I have a habit of saying exactly what I want, rather than implying it. SL93 (talk) 09:34, 30 July 2013 (UTC)

You didn't help me. I know of lucid dreaming, but nothing that you linked mentions pain being involved. Someone even asked for a reliable source on the talk page for REM sleep. No wonder it isn't in the article. SL93 (talk) 09:37, 30 July 2013 (UTC)

Yes, there have been reports (other than yours) of people feeling pain in their dreams. It isn't common. Just search for pain+dreams in Google Scholar. You will then be in a position to update the REM sleep article. Sean.hoyland - talk 10:05, 30 July 2013 (UTC)

Thanks for the tip, but I have no interest in updating the article. SL93 (talk) 10:07, 30 July 2013 (UTC)

I feel pain in dreams fairly often. I was surprised a few years ago when I saw a thread on here about c-fiber nerves and people claiming that it is impossible to feel pain in dreams. I challenged it and nobody offered up a counter argument or any sources, and I haven't been able to find anything concrete one way or the other myself. But I assure you, when someone in a dream is cutting my fingers off or stabbing me, I feel it. 82.44.76.14 (talk) 10:31, 30 July 2013 (UTC)

• I'll just note that this question has come up before. Looie496 (talk) 14:08, 30 July 2013 (UTC)

It appears than dreams can contain just about anything that real life can contain - including hearing, taste, feeling etc. Brains can be weird <g>. Collect (talk) 15:57, 30 July 2013 (UTC)

The OP asked if there had been reports of people feeling pain in dreams. Certainly I have had dreams in which pain played a part, after surgery, when there was a sore back, when there was tonsilitis, when there was a belly ache. The dream incorporated and explained the pain in some way. The dreaming process sometimes explains away stimuli in such a way that you can just go on sleeping. A Google book search will reveal countless books discussing pain in dreams, though many of them are "new age" self=help books or religious books. Freud, in "The interpretation of dreams" p190 mentions "headache dreams" and "toothache dreams." Edison (talk) 16:11, 30 July 2013 (UTC)

• On the occasions I have felt pain in my dreams it was always because of some real stimulus outside of my dream, such as thinking my leg is in a bear trap to wake up and find I am in a twisted position and it has fallen asleep, or feeling that my mouth is full of ashes and my teeth are falling out to wake up and find I am gagging because I have been mouth-breathing and my mouth is entirely dried out. This seems to be the brain rationalizing the real stimulus into the dream. But I cannot say I have ever felt a pain in a dream without some external reason. The exception seems to be sex dreams, which can be very pleasantly authentic feeling without any real external stimulus. μηδείς (talk) 16:21, 30 July 2013 (UTC)

Original research: I've personally had at least four dreams involving physical pain: on one occasion, I dreamed that I was shot to death right through the heart by a crooked cop; on another, that my mouth and throat were stuffed full of sharp plastic shards (this was when I was down with strep throat and bacterial sinusitis on top of that); on the third occasion, that I was bayonetted to death (also right through the heart) by a Red Army soldier (of the four, this was the dream I remember best -- in that dream, I was a White Army squad leader during the Russian Civil War, and me and my squad had just ambushed a Red Army column but bit off more than we could chew, so we all died fighting); and on the final occasion, I dreamed that I was shot in the chest by a gangster, but survived and had enough strength to strangle my attacker. So yeah, it can totally happen -- and also, you CAN dream that you were killed without actually dying (contrary to a popular misconception). 24.23.196.85 (talk) 02:44, 31 July 2013 (UTC)

So Nightmare on Elm Street was wrong? :( SL93 (talk) 04:22, 31 July 2013 (UTC)

Well, the difference here is, I don't have casual sex with every Tina, Dolly and Helen that I meet (unlike the characters in that movie), which means I'm safe on that end. 24.23.196.85 (talk) 08:40, 31 July 2013 (UTC)

So the possibility exists that you suffered real chest pains which were then incorporated into you nightmare. For chest pains, you would want to consult a doctor, but these are possibly dreamt chest pains. I'm not sure what the medical guidelines are for reporting those. Also, your sleeping position could possibly cause cramps in the chest muscles, which your brain interpreted as the heart. But, do you get chest pains during the day ? If so, you should definitely see a doctor. StuRat (talk) 09:05, 31 July 2013 (UTC)

No, I don't get chest pains during the day. And I normally sleep facedown, if this matters. Or were you replying to SL93? 24.23.196.85 (talk) 00:30, 1 August 2013 (UTC)

This is pure OR, but in one of my lucid dreams, I decided to test the hypothesis (often assumed to be true in cartoons for children) that you can't feel a pinch in a dream. I pinched myself and definitely felt the pain--it felt very similar to a pinch in real life. --Bowlhover (talk) 22:14, 31 July 2013 (UTC)

Lucid dreams are fun. One example is where you become lucid whilst in a painful situation, and then decide that since you're dreaming, you may as well will the situation to become painless, continue to mold the dream into anything you can imagine. However, the tricky part is remembering that you are dreaming. It is all too easy to forget, and slip right back into a non-lucid dream. It takes practice to avoid either waking up from a lucid dream, or retaining lucidity. You have to remain in perfect equilibrium, concentrating to remain relaxed and aware in a balanced manner. Occasionally, it is possible to regain lucidity within the same dream. Once in a lucid dream, I changed the taste of an apple to that of a blueberry. Another time, I wanted to fly, so I did. Halfway through my flight, I lost lucidity for a moment, and fell to the ground from ~50 m up. I got the wind knocked out of me, but was otherwise just fine. Strange, I thought that it would be a bit more painful than that. Plasmic Physics (talk) 01:01, 1 August 2013 (UTC)

I would love to see some sources here, but I'm not sure where to begin because I can't think of how to do the experiment. I know, for example, that to me sleep and pain are so incompatible that when I had the gout I would avoid moving/"awakening" my legs for an hour after awakening to maintain sleep paralysis, preventing any sensation of the quite severe pain from the attack, but I haven't found any commentary about that (pity, because it ties into hypnosis for pain relief and perhaps more serious issues...) Wnt (talk) 04:53, 1 August 2013 (UTC)

Deaths Cap in homeopathy and well poisoning

I have read that death's cap is responsible for most mushroom poisonings; including the deaths of a few roman emperors; which makes me wonder how often it was used in medieval well poisonings. I know that is a rather sensational subject from hundreds of years ago and the numbers were inflated for propaganda purposes; but there were at least some recorded instances. I recently tried adding an article I found on PubMed Central about the use of Amanita phalloides homeopathically to treat B-cell chronic lymphocytic leukemia. I'm aware that a single study needs to be repeated; which is why I'm not contesting the removal. Now I don't believe in water memory; but what is the difference between homeopathy and diluting something in water; wouldn't diluting poison with water allow for smaller amounts of it to be consumed? They do say that the poison is in the dosage. I'm also confused as to whether alternative medicine journals are legitimate primary medical sources when they are from the NIH or other government health organizations. Here is the link; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3151460/. Thanks for answering these questions. — Preceding unsigned comment added by CensoredScribe (talk • contribs) 19:04, 30 July 2013 (UTC)

Homeopathy is tricky. The homeopaths have their own special backdoor into the medical racket, allowing them to dispense "treatment" and "medicine" according to their own peculiar standards. In practice, there are two different kinds of homeopathy encountered: one uses astronomically high dilutions to sell tap water to unsuspecting customers, given sometimes even by mainstream physicians who have applied medical ethics (i.e. profit) to determine that the act of patients giving them money for bogus medicine will make them feel better. The other, more interesting variety, uses absolute minimum homeopathic dilutions to deliver genuinely therapeutic treatments - the catch being that they are not medically evaluated and they have the potential to harm as readily as heal. For example Zicam causing loss of smell, [1], and others. In this case, the amanitin is diluted by "D4" (1:10000) and 5-40 drops are given. Sometimes homeopathy includes a hidden dilution factor (a drop flicked into a bottle of sugar pills) but it is not guaranteed and I don't think we should count on it here. So there is possibility of a beneficial effect, but the utmost skepticism is required! Wnt (talk) 20:14, 30 July 2013 (UTC)

Right, be careful about identifying homeopathy with homeopathic dilution. Homeopathic dilution is the aspect of homeopathy that probably gets the most attention, but it isn't the whole discipline, just one practice. Homeopathy is an entire framework of (mostly if not entirely bogus) theory and (possibly occasionally effective and/or dangerous) practice. --Trovatore (talk) 20:23, 30 July 2013 (UTC)

Symbol/syntax for denoting an (intentional) error?

Hi, in the Orders of magnitude (speed) article, I wanted to highlight the fact that the speed measured in the Faster-than-light neutrino anomaly is "incorrect". Is there a symbol or syntax I could use to denote an intentionally incorrect value or item (in science)? I thought I could use italic for the values, or maybe an asterisk or something similar, but I frankly have no idea. Thanks in advance. --CesarFelipe (talk) 21:44, 30 July 2013 (UTC)

• Won't [sic] do? Or a footnote? - Nunh-huh 21:47, 30 July 2013 (UTC)

Just asterisk/footnote or other text annotation would be good. It's a disproven or contradicted statement, not a typo that would merit "sic". DMacks (talk) 22:00, 30 July 2013 (UTC)

MPN / CFU relationship

Hi Guys,

Is there a direct relationship or conversion factor for comparing fecal coliform results by enzyme reaction reported as MPN and results by membrane filtration reported as CFU? Thanks! — Preceding unsigned comment added by 148.66.156.178 (talk) 22:02, 30 July 2013 (UTC)

No simple conversion seems possible but models have been proposed to compare results of the two methods. Also results may depend on circumstances, for example a Korean study found MPN for e. coli larger than CFU, except in winter. On the other hand, enterococci were lower in MPN than in CFU.

Maybe this helps: "Modeling the relationship between most probable number (MPN) and colony-forming unit (CFU) estimates of fecal coliform concentration." Gronewold AD, Wolpert RL. pdf download. Ssscienccce (talk) 10:51, 31 July 2013 (UTC)

Thanks, that helps a bunch! I didn't think they directly related but it seems they are at least roughly comparable as my results are either near zero or in the 20-30k range. — Preceding unsigned comment added by 148.66.156.178 (talk) 00:26, 2 August 2013 (UTC)

July 31

Visibility of the New Moon

The Wikipedia entry for New Moon states 'The Moon is not normally visible at this time except when it is seen in silhouette during a solar eclipse'. While driving from California to New York on Interstate 10 I pulled over early in the morning in the desert to stretch my legs. I look up at a perfectly clear night sky and saw the entire surface of the moon un-illuminated. What phase of the moon was I viewing? — Preceding unsigned comment added by 66.65.43.46 (talk) 00:56, 31 July 2013 (UTC)

If the Moon is closer than 7.5 degrees from the Sun, there is no visible crescent see here. Count Iblis (talk) 01:11, 31 July 2013 (UTC)

If we assume that your recollection is accurate, then you saw a lunar eclipse—at night you can't see the new moon because the Earth is in the way. TenOfAllTrades(talk) 01:32, 31 July 2013 (UTC)

The Muslims often take good pictures of very young crescent moons for Ramadan

Yep, that's the only possibility. In addition to what you've quoted regarding the new moon, it's also only above the horizon during daylight hours (layman's definition, not astronomical). It's impossible to see a new moon, or see a dark disc where a new moon would be, at night. — Lomn 01:38, 31 July 2013 (UTC)

No! No! A new moon can be above the horizon shortly after dusk or before dawn, and it is illuminated by earthlight, which is easily bright enough to make it visible in good conditions. (Earthlight is over ten times as bright as moonlight.) Looie496 (talk) 02:32, 31 July 2013 (UTC)

In an area with high levels of nighttime illumination (such as in large cities), it's also possible for a new moon to be darker than the night sky, and therefore visible as a dark circle. 24.23.196.85 (talk) 02:54, 31 July 2013 (UTC)

Skyglow over cities is caused by light that originates on Earth, and is then scattered back down from within the Earth's atmosphere. The Moon cannot obstruct this light, because the light goes nowhere near the Moon. So, no dark spot in your city sky. TenOfAllTrades(talk) 03:26, 31 July 2013 (UTC)

It is possible but unlikely that he saw it during a total lunar eclipse. But then it would have been reddish, and he didn't report that. Bubba73 ^{You talkin' to me?} 02:36, 31 July 2013 (UTC)

I have seen a full lunar eclipse (as well as a full solar eclipse) and it was not a eclipse. I was in the high New Mexico desert at the time, late November perhaps 4 or 5 AM, and it seemed to me that it was being illuminated by the Earth's albedo. I have posed the question because there seems to be differing views as to what I saw is in fact possible. — Preceding unsigned comment added by 66.65.43.46 (talk) 02:54, 31 July 2013 (UTC)

That's not a bad hypothesis, and it's one I've thought about too. Unfortunately, the sky at twilight – after the Sun has set, but before the sky is fully dark – is bright enough to completely wash out the Earth-lit new Moon. The Moon can't get much further than about 7 degrees from the Sun before it starts to show a visible crescent, which means that even under ideal conditions you're just at the edge of civil twilight. (Go ahead and search—you'll find that there just aren't any images of a new, non-crescent moon at twilight. I will also note, for the record, that I have another reason to hate Stephenie Meyers—her silly vampire books and movies hopelessly contaminate Google image searches for new moon and twilight.) TenOfAllTrades(talk) 03:34, 31 July 2013 (UTC)

A quick question or two: (1) it was in the early morning - was it just before sunrise? (2) Was the Moon in the same direction as the rising Sun? A new Moon would be close to where the Sun would rise. In a lunar eclipse, the Moon would be opposite the Sun. Bubba73 ^{You talkin' to me?} 04:01, 31 July 2013 (UTC)

And what was the date on which you saw this?--Shantavira|^{feed me} 07:34, 31 July 2013 (UTC)

List of lunar eclipses here. In 2012 there was a penumbral on nov 28, mainly visible between 14:00 and 15:00 UT, that would be between 7:00 and 8:00 local time? Ssscienccce (talk) 09:50, 31 July 2013 (UTC)

I don't believe that one can see a perfectly unsunlit moon for the reasons given above, but it's certainly possible to see a very thin crescent moon with the rest of its visible disc faintly illuminated by earthshine. This has traditionally been referred to as "seeing the new moon in the old moon's arms", as in the ballad of Sir Patrick Spens. There's a good image here. Deor (talk) 12:46, 31 July 2013 (UTC)

To somehow detect Everett's "other worlds": some new "telescope?"

Hi, I'm certainly a layman, but i was thinking that if Hugh Everett's Many worlds interpretation does turn out to be true, then physics needs a new "telescope", that is, an instrument as radical as the telescope(and microscope too) were in the 1600s, in order to "see", that is, somehow detect the other worlds. I'm wondering if the new "telescopes" could be experiments at temperatures much colder than they've done yet. I mean, I have heard of physicists getting down to .1 degree kelvin, but maybe the clues could be there at .00001 kelvin, or even 10^(-40) kelvin? And what are the hopes right now for getting these much lower temps? Thanks76.218.104.120 (talk) 09:29, 31 July 2013 (UTC)

I just read a reference to a proposed experiment to detect them by Plaga! He would use ions in some way.76.218.104.120 (talk) 09:35, 31 July 2013 (UTC)

Please forgive me for not checking, wikipedia says they are down to a few hundred nanokelvins now. I got up late at night with an idea that was exciting to me and i didn't read up. But the general direction of my first and second questions still stand, but they are much closer to 10^-10 than I thought. So, my second question can be revised to what would be the outlook for even lower temps, for example 10^-10000 k? Thanks again.76.218.104.120 (talk) 09:50, 31 July 2013 (UTC)

The problem is that the different interpretations of quantum mechanics yields the same predictions for the outcome fo experiments. The only way to test the Many Worlds Interpretation (MWI) is to think of some very unusual experimental set-up that would yield a different prediction. As long as you have the usual type of quantum experiments where the observer is treated classically, you will not see any difference. The only way to get a difference is to think of an experiment where the observer is itself going to participate in a non-trivial way in the epxeriment where a de-facto calssical description of the observer (due to quantum decoherence) is not a valid assumption anymore.

David Deutsch came up with such a thought experiment back in 1985. This involves an observer who can be perfectly isolated from the environment. He prepares an electron with its spin polarized in the x-direction. He then measures the z-component of the spin. This measurement can yield two outcomes with equal probability, spin up or spin down. In the MWI both measurement outcomes really exist, but you'll find yourself in one of them. So, how would you know that the other outcome also exists? Well, since you are perfectly isolated, you could in principle reverse all the steps made in the measurement process, ending up with the electron spin polarized in the x-direction. However, you would not know anymore that you had previously measured the spin of the electron, as your memories would also have to be reset in that reversal process.

What you can do is keep in your memory is the information that you did perform the measurement, the transformation back to the initial state is then still a unitary transform (an easy exercise to check) and thus relaizable in principle. You cannot keep the result of the measurement; because this is different in the two branches where the measurement result is different, you won't get the electron back in its original spin state polarized in the x-direction. This verifies the physical existence of the two different measurement outcomes, because both are needed to get back to the initial state.

Of course, this experiment as originally proposed by Deutsch is impossible to perform in practice, however a few years later people came up with the concept of a quantum computer. If very large scale quantum computing ever becomes a reality, you can contemplate simulating an artificially intelligent entity inside a quantum computer and that entity could then perform Deutsch' experiment. Count Iblis (talk) 13:45, 31 July 2013 (UTC)

thanks, very good exposition.76.218.104.120 (talk) 21:51, 1 August 2013 (UTC)

Is the moon in the sky exactly as often during the day as during the night?

That is, if I timed how long the moon was in the sky during the day, and how long it was in the sky during the night, over a long enough period, would I get identical answers?

Be as picky as you want about details, and do please try to quantify your answers: I'm interested in whether the various skewed orbits and other factors make a difference. 86.164.26.17 (talk) 10:02, 31 July 2013 (UTC)

You should to a first approximation. Now, you see more of it at night because the full moon is at it's zenith at local midnight, while the new moon is at zenith at local noon. But averaged out over an arbitrarily long time, there are no stretches of any 24 hour cycle when the moon is in "the sky" more than at other times. --Jayron32 11:16, 31 July 2013 (UTC)

You never get things like that exactly the same if you measure closely enough. Lets just consider the moon to be a point to simplify things. The sun isn't a point so that makes days longer than nights. Refraction makes the light go further so that also makes days longer. Discounting those two factors the earth has a width so with a point sun the day is a little bit shorter than the night if it rotates evenly. The earth goes in an ellipse round the sun which I believe means the northern hemisphere gets slightly more daylight as the earth is farther away from the sun and goes slower when it is tilted towards the sun. Discounting the tilt as well we have the problem of the speed of the moon as it orbits the earth, I think it should be going slightly faster when it is on the sun side so that would mean it is more often out at night. And I haven't started on earthquakes or the other planets. Anyway the most important factor discounting refraction is the width of the sun I believe so you would have it more often in the day than the night. Dmcq (talk) 13:27, 31 July 2013 (UTC)

Seems that Dmcq has already given the reasons for the two not being equal: sunrise and sunset are defined as the moment the upper edge of the sun is at the horizon, and atmospheric refraction. When considering twilight, the difference becomes larger, see definitions here. I calculated the total time the moon would be visible at 0°W 20°N during 2013, using the tables you can generate here; results: moon visible during the day for 134937 minutes (2248.95 hours or 93.706 days), and during the night for 128363 minutes (2139.38 hours or 89.14 days). Some other numbers: total daytime 184.68 days, nighttime 180.31 days; moon for 182.85 days, no moon for 182.15 days Ssscienccce (talk) 13:40, 31 July 2013 (UTC)

Same calculation for 0°W 60°S gave: moon during the day: 132561 minutes, during the night: 125251 minutes. (92.06 vs 86.98 days) Total daytime 185.18, nighttime 179.82 days; moon for 179.04 days, no moon 185.96 days total.

Of course the start and end date will influence the results since the moon's position won't be the same after 1 year..Ssscienccce (talk) 13:58, 31 July 2013 (UTC)

The moon is always in the sky, isn't it? Mingmingla (talk) 16:46, 31 July 2013 (UTC)

Are you counting the new moon? Because although the moon is in the sky during the day, a human eye will not be able to see it. Also the thin crescent moons are not that obvious during the day, so are you counting that as being in the sky, as you have to look carefully to notice it. So the moon is certainly less noticeable in the day than at night. guess you knew that! Graeme Bartlett (talk) 21:51, 31 July 2013 (UTC)

• Over a long period of time (probably on the order of some years) the moon will average the same period of time over any longitude during day as night. That's intuitively obvious, but you can ask for an explicit explanation at the math desk. μηδείς (talk) 18:46, 1 August 2013 (UTC)

Electron Affinity of flourine< chlorine, why?

Why is the electron affinity of flourine low then that at chlorine? — Preceding unsigned comment added by 202.70.84.89 (talk) 15:17, 31 July 2013 (UTC)

If you're talking about the Pauling electronegativity, then fluorine does not have a lower electronegativity than chlorine, but a higher. Plasmic Physics (talk) 22:41, 31 July 2013 (UTC)

No. That's a related, but different parameter. See Electron affinity. Dominus Vobisdu (talk) 23:12, 31 July 2013 (UTC)

My apologies, I haven't thought critically about these things for a long time. I have heard of electron affinity, the term just escaped my mind prior your link. Plasmic Physics (talk) 00:45, 1 August 2013 (UTC)

The reasons why fluorine is anomalous are explained in detail here: [[2]]. Dominus Vobisdu (talk) 23:12, 31 July 2013 (UTC)

The easiest explanation, although it may not be completely correct, as I was taught to memorize and recite, is that the 2p orbital you would have to insert the electron into experiences significantly more electrostatic repulsion with the electron that is already in that orbital. While the effective nuclear charge for chlorine's 3p orbital is lower than for fluorine's 2p (which would explain why fluorine has the greater electronegativity), it has much less electrostatic repulsion than fluorine's 2p orbital, which makes the chlorine 3p orbital the lower energy state.--Jasper Deng (talk) 00:53, 1 August 2013 (UTC)

F itself isn't the special-case/anomaly. F being low (or Cl being high) in F→Cl→Br→I is the same pattern as O→S→Se→Te (O is low or S is high) and likewise for the carbon and boron groups. The link Dominus Vobisdu mentioned mentions this pattern for the second row vs third row. DMacks (talk) 01:55, 1 August 2013 (UTC)

Utilization of infrared, solar cells.

Greetings!

I am somewhat puzzled by the advent of solar-power generators capable of producing electricity from the infrared part of the spectrum. For starters, I've heard that they can generate power in all kinds of weather—even at night! Also, I've heard that the only reason we (end users) don't have them is because they produce electricity at about 10 THz, making them totally useless with which to run our appliances, which typically run at approximately 50 to 60 Hz.

I have two quick questions; namely, how exactly can a solar cell generate power at night? Does it utilize infrared light, from the Sun, absorbed by Earth's atmosphere during the daylight hours, or perhaps, infrared radiation arriving here from more-distant stars? Also, (and I apologize in advance, if this is stupid question) just how impractical and unwieldy would it be to just nix all of 50-60 Hz electronics and replace them with 10 THz ones—the way we did with regular gasoline, and are currently doing with analog television?

Would be the cost greatly outweigh the benefit of living free of power plants, dams, coal mines, transmission lines, et al? Thank you.Pine (talk) 20:57, 31 July 2013 (UTC)

Sounds unlikely. Do you have a source? Maybe it got a bit distorted in transmission or in recall. The frequency you say it produces electricity is only a little lower than for infrared, and certainly it could not be transmitted over power lines. See Terahertz radiation, Infrared. Photovoltaic Solar cells produce direct current. Mirror arrays can concentrate sunlight on a boiler and probably could produce power from infrared if there were enough of it hitting the mirrors, but residual heat in the atmosphere, or moonlight, or starlight would not be enough. And if the mirror array did boil water, then the generator would produce plain old electricity unless you somehow had a microwave generator or like which ran on heat, or the concentrated black electromagnetic energy just heated something up so it radiated black body radiation. Edison (talk) 21:34, 31 July 2013 (UTC)

I found an article Third generation photovoltaic cell which mentions advanced solar cells making electricity from infrared at night, but it links to a dead reference, so it is less than convincing. Edison (talk) 21:40, 31 July 2013 (UTC)

Solar cells can respond to near infrared with wavelengths shorter than about 1 micron. You don't get much of this at night at all, as it comes from the sun like normal visible light. When you get the longer wavelength thermal infrared, solar cells do not turn this into electricity in any significant amount. THey are just as likely to do the reverse process and radiate thermal infrared. The issue here is entropy. Note there are other techniques such as solar thermal power. Graeme Bartlett (talk) 21:42, 31 July 2013 (UTC)

I found an IEEE article from 2012 which discusses Terahertz power generation. It generally has less than 1% conversion efficiency in generating the Terahertz output, and such EM radiation is reduced severely as it travels through the atmosphere. Edison (talk) 22:05, 31 July 2013 (UTC)

The OP may be referring to so-called nano-antennas that receive the IR energy as electric signals which after rectifying would result in usable energy. Very promising it seems "Unlike solar cells, nano-antennas can operate round the clock, independently of weather conditions such as humidity and cloud cover and without restriction of orientation towards the sun.", but when the rectifier is discussed, the optimism wanes: "The implementation of rectennas for energy harvesting at IR frequencies has remained an elusive research area due to the limitations of nanoscale fabrication and inability to implement rectifiers that could handle EM radiations oscillating at trillion times a second." And I assume the solar panels would have to be raised in the air (and receive IR from the ground), otherwise the laws of thermodynamics would prevent "round the clock" operation. Ssscienccce (talk) 00:52, 1 August 2013 (UTC)

The downward IR radiation for a visibly clear sky is about 70% of the upward IR radiation from the ground. Dragons flight (talk) 06:38, 1 August 2013 (UTC)

Yes, that's the reason why panels on the ground can't generate motive power at night; it would violate Carnot's theorem. Ssscienccce (talk) 19:53, 1 August 2013 (UTC)

How do you determine if a bird is fat?

I was just looking at this photo and it made me think. How do you determine the difference between a really fat bird and a bird that's just very fluffy? Is there a reliable thing to look for? --87.114.229.248 (talk) 22:06, 31 July 2013 (UTC)--87.114.229.248 (talk) 22:06, 31 July 2013 (UTC)

Several methods are possible, of which the two most obvious quick and sloppy methods are weight/length ratio and thigh circumference/length ratio. These presupose that you have reference data for the specific population in question. If you mean by mere sight, an experienced observer could probably make an educated guess. Again, depends on long-term observation of the population. You can find more sophisticated measurement methods like ultrasound and x-rays by Googling measuring body fat content in birds. Dominus Vobisdu (talk) 22:36, 31 July 2013 (UTC)

You could kill it and use standard food analysis techniques. Although bird lovers may not like that approach, IRWolfie- (talk) 23:52, 31 July 2013 (UTC)

I have chickens who confuse me the same way. Three are basically identical, except there's a small, a medium and a large. Now and then, the small one looks bigger than the big one. While they're ruffled, it's hard to tell by sight. I'd say feel it, but that's obviously not easy with an owl.

In this guy's case, note how deep the branch is into his body. Probably safe to assume that's not flab, and that he's at least equally feathery on the other side. I'm no expert on fish owls, but he doesn't look particularly fat to me. InedibleHulk (talk) 00:39, 1 August 2013 (UTC)

Can he fly uphill or only downhill? --catslash (talk) 00:42, 1 August 2013 (UTC)

Can birds get fat at all? Birds have a very high power to weight ratio, allowing them to fly. So, it seems to me that if they could get obese, that would compromize their ability to fly. Count Iblis (talk) 01:05, 1 August 2013 (UTC)

If you've ever had the pleasure to cook a goose, you would know that some birds, at least, can accumulate an enormous amount of fat. Dominus Vobisdu (talk) 02:09, 1 August 2013 (UTC)

Birds that fly can't get all that fat, no. The leaves us with flightless birds and chicks, where fat may be advantageous for the usual reasons (insulation, surviving periods of famine, etc.). StuRat (talk) 06:07, 1 August 2013 (UTC)

I think the OP is using "fat" colloquially, as in the opposite of thin, not necessarily the opposite of skinny. There's a great clip on youtube from a japanese tv show, you can find it if you search for transformer owl. it shows an owl trying to make it self look "fat" and then trying to make it self look skinny, it's quite incredible. Vespine (talk) 01:42, 1 August 2013 (UTC)

I don't know if it is inferable, but I once had a cockatiel which would get exhausted from just circling three times within our twin garage. We took it for a fly several times a week, just like you would take a dog for a walk. Maybe it was just not very fit when it came to flying, but not fat? Plasmic Physics (talk) 01:45, 1 August 2013 (UTC)

Of course you can get truly fat birds: ducks for example are prized for their fat and along with geese are "fattened" on purpose for fois gras. I imagine penguins too would have some fat for insulation. But I agree those would be the exceptons amongst wild birds, expecially if you only count flying ones. Vespine (talk) 06:28, 1 August 2013 (UTC)

Here is an interesting cross-section showing just how much of an owl is feathers: [www.neatorama.com/2012/04/17/owls-are-all-feathers/‎] 209.131.76.183 (talk) 11:40, 1 August 2013 (UTC)

Phyllis Diller, without her yellow Peep consort

• I am sorry, but that has to be about the ugliest non-moulting non-chick I have ever seen. And apparently the inspiration for Big Bird. 18:43, 1 August 2013 (UTC)

I wouldn't call it ugly, but it won't win a beauty contest either, I'll resign to calling it odd-looking. It brings to mind what the result could be if you visually combine a housecat with a hawk. Plasmic Physics (talk) 01:11, 2 August 2013 (UTC)

I second all of that. My first thought was that it had the exact same eyes as one of my housecats (who is hairy and unquestionably obese, but not quite repulsive). InedibleHulk (talk) 06:22, 4 August 2013 (UTC)

More like a Swifter and a used Hoover bag with a beak. Or Phyllis Diller and a yellow Peep. μηδείς (talk) 01:16, 2 August 2013 (UTC)

The Chicken Lady is more what I think of if Diller got any birdier. No murdered women in this one, but you may still find her disturbing. Discretion advised. InedibleHulk (talk) 06:28, 4 August 2013 (UTC)

A more serious answer is yes, you can tell if a captive bird is in good condition by catching it, and feeling for how "full" the big muscles either side of the breast bone are. I'm not sure how to find an illustration, it may be just something you learn by experience. Any bird breeder can probably show you how to do this. Snake experts use the same sort of guide by looking at how full the muscles are beside the backbone, and a rating for "fatness" of Koalas has been developed by feeling either side of their spine in the lumbar region. 122.108.189.192 (talk) 07:57, 3 August 2013 (UTC)

August 1

Atomic spectrum

What is meant by atomic spectrum? — Preceding unsigned comment added by 202.70.84.91 (talk) 01:56, 1 August 2013 (UTC)

Our atomic spectrum article would be a good place to start. DMacks (talk) 01:57, 1 August 2013 (UTC)

Live flu vaccine causes extroversion?

I read in a news article that in a study, subjects displayed more extroverted behaviour (e.g. were more likely to socialize with strangers) after receiving a live attenuated flu vaccine. The explanation implied by the article was that the flu virus (for which the vaccine was presumably a proxy, for ethical reasons) had evolved this effect in order to spread faster. Can anyone provide the original citation? Was it a DBPCT or just a correlational study? NeonMerlin 02:54, 1 August 2013 (UTC)

There are many studies about this, of varying quality and with varying conclusions. See [3] and [4]. Maybe if you linked to the news article, someone could figure out which one they are talking about. Someguy1221 (talk) 10:35, 1 August 2013 (UTC)

Does astrology say anything about when technological/social progress has head/tailwinds?

It's all baloney of course, but fiction is still entertaining. Any lists of planet(s) by sign or something out there? Re:1846-48, they've got some explainin' to do: ether, chloroform, cameras, Neptune, telegraphs, democratization and Marxism, lol. 108.27.81.195 (talk) 09:25, 1 August 2013 (UTC)

This is a science desk. Since it's fiction, there is no correct answer. Find the Folklore and crystal dangling desk. — Preceding unsigned comment added by 217.158.236.14 (talk) 10:26, 1 August 2013 (UTC)

I think that the Humanities reference desk is the right place to ask about astrology. Sjö (talk) 10:47, 1 August 2013 (UTC)

Yep. Astrology isn't science. Take it somewhere else. HiLo48 (talk) 10:57, 1 August 2013 (UTC)

For those interested there is astrology and science, IRWolfie- (talk) 18:32, 1 August 2013 (UTC)

Astrology may not be a science but, as the OP remarked, astrologically speaking the discovery of Neptune has a lot to do with the discoveries/inventions that the OP lists. We also have an article which the OP should consult: Planets in astrology --TammyMoet (talk) 11:32, 1 August 2013 (UTC)

Wait a minute... the discovery of Neptune had an astrological effect? Wnt (talk) 15:58, 1 August 2013 (UTC)

Yes, Wnt, the time a planet comes into the consciousness of mankind is deemed to be the time that planet starts to affect mankind. --TammyMoet (talk) 19:25, 1 August 2013 (UTC)

So, when Pluto was degraded to a non-planet, it affected people? OsmanRF34 (talk) 22:57, 2 August 2013 (UTC)

Well they had to invent new claims about the planet, Astrology_and_science#Lack_of_predictive_power. IRWolfie- (talk) 18:32, 1 August 2013 (UTC)

Why only 2nd period elements show diagonal relationship?

Only 2nd period elements exhibit same property which resembles not only with the property of it's own group members,but also with the members of next group which is one period below ...Why? — Preceding unsigned comment added by Amrit.ghimire13 (talk • contribs) 16:14, 1 August 2013 (UTC)

What are you implying, that the other periods do not, or that period one specifically does not, or something else? Plasmic Physics (talk) 01:08, 2 August 2013 (UTC)

I am implying that why other periods do not show such property? Why only 2nd period only show it?

User:Amrit.ghimire13 (talk — Preceding unsigned comment added by 202.70.84.93 (talk) 01:32, 2 August 2013 (UTC)

Then I am confused, because all the periods show trends in both horizontal and vertical directions, and thus logically diagonally also. The trends may not be linear, but they exist nonetheless. Plasmic Physics (talk) 07:18, 2 August 2013 (UTC)

Why are underground power lines still vulnerable to electrical storms?

Topic^ ScienceApe (talk) 16:33, 1 August 2013 (UTC)

Fulgurite. μηδείς (talk) 18:41, 1 August 2013 (UTC)

Underground powerlines are still connected to things above the ground, wouldn't be much use otherwise. And stuff above the ground gets hit by lightning sometimes... Ssscienccce (talk) 23:00, 1 August 2013 (UTC)

Underground distribution cables, and a few thousand volts, are often plastic-jacketed cable buried just a few feet underground. Lightning has little trouble travelling the short distance into the ground to hit the nice metallic ground sheath in the cable, having travelled miles down through the air. Even without a direct strike, if it hits the portion of the underground cable that comes up and connects to the system at the top of a pole, the spike can stress the cross linked polyethylene insulation leaving "trees" of insulation breakdown which later turn into a solid fault. Edison (talk) 03:03, 3 August 2013 (UTC)

Is it even remotely possible that this isn't a scam?

Here's an interesting Kickstarter Project that claims to "Filter out" the greenhouse gasses from your car's emissions.

CO2ube

Correct me if I'm wrong, but isn't that thousands of pounds worth of material?

(They answer this idea by vaguely mentioning that they're using photosynthesis to make the carbon disappear. But that just raises further questions!)

Am I missing something? Is there even the slightest chance that this is real?

75.69.10.209 (talk) —Preceding undated APL (talk) comment added 21:25, 1 August 2013 (UTC)

Sugar is a very good source of energy. If something that size could do that easily then you would be able to take the sugar it produces and run an engine from it - which would produce the carbon dioxide again for that to turn into sugar again. Not quite a perpetual motion machine but at that size with so little access for sunlight practically so. Dmcq (talk) 22:23, 1 August 2013 (UTC)

The principle that photosynthesis removes CO_2 from the air is sound. They don't seem to claim to eliminate CO_2 emissions, just reduce emissions. Really, any old can of algae can do that. It remains unclear just how effective this design is, and what its life cycle analysis might be. For instance, though CO_2 is likely trapped in the algae, what do you do with said algae when you clean the filter? If you throw it in the trash or compost, the CO_2 will be back in the air in a few years (or less), due to decomposition. I wouldn't call it an outright scam, because I believe their device can reduce tailpipe emissions. But I am highly suspicious of the long-term benefits of such a system. Perhaps it would be most useful to prevent smog in e.g. L.A. Even if the total offset of emissions is small, there may be value in distributing the emissions more evenly (e.g. far from urban centers, where they pose health risks). My WP:OR is, if you want to reduce your carbon footprint, invest in a bike, move closer to work, and plant a few trees. (Post EC with DMCQ, re-using the sugars for usable energy would indeed be a good idea, and there are plenty of bright people working on said biofuels) SemanticMantis (talk) 22:27, 1 August 2013 (UTC)

"We have grown multiple generations of algae colonies to find the most suitable strain for the heat and pressure of the exhaust system (artificial selection)." Suitable for 900°F / 500°C, really?... Ssscienccce (talk) 22:46, 1 August 2013 (UTC)

There seems to be some consideration for radiating heat. Are tailpipe gases really at 500C a few inches past the end of the pipe? SemanticMantis (talk) 23:44, 1 August 2013 (UTC)

Even if we take it for face value, any removed C would wind up in the filter one way or another. Photosynthesis doesn't make C disappear. So it'd be a worthlessly small amount of C.

That's the part I'm questioning, you'd need a place to put all the C, right? It can't just be "filtered out" into nothingness. So there's no way this filter, photosynthesis or not, could remove a useful amount of carbon. (A single tank of gas probably represents hundreds of kilos of algae-manufactured sugars.)

Unless I'm missing something really important, which is why I asked.

(Of course, this alleged photosynthesis would be taking place inside an opaque black tube.) 75.69.10.209 (talk)APL (talk) 00:16, 2 August 2013 (UTC)

Indeed; in this universe we obey the law of conservation of mass. Gasoline and diesel fuel are both upwards of 80% carbon by mass, and even ethanol is more than 50% carbon. The important reaction here appears to be the reaction of water vapor and carbon dioxide with sodium hydroxide to form solid sodium carbonate, thereby 'reducing' the carbon dioxide output (at least until all of the sodium hydroxide is consumed). The algae in the product appears to be a red herring; at best it's a matrix that enables the device to disperse the solid sodium carbonate out the tailpipe.

One mole of sodium hydroxide reacts with one mole of carbon to produce one mole of sodium carbonate (via various intermediates and producing some other unimportant products); to fully sequester the carbon from a kilogram of gasoline will require something like three kilograms of sodium hydroxide. That fist-sized device couldn't hold even a full kilo of NaOH even if it were the solid material; one tank of gasoline contains 40 kilos of carbon. You do the math.

One also wonders if the increased back pressure on the exhaust system (caused by the partial obstruction introduced by this device) might not have a detrimental effect on fuel efficiency. TenOfAllTrades(talk) 03:21, 2 August 2013 (UTC)

I'm pretty confident the device does not work. But where do we even begin enumerating its many flaws? The rate of exhaust-gas production is orders of magnitude faster than any algae can grow. Conservation of mass flux inside a tube is about as simple a problem as you can get: if you can't "use up" or convert the carbon exactly as fast as the engine produces gases, then you either overpressure the exhaust pipe (unsafe!) or you vent the exhaust gas to the outside world.

Also, automotive exhaust isn't just carbon dioxide. It's also carbon monoxide, soot, trace heavy hydrocarbons, unburned fuel, trace nitrates, sulfates, oxides of those; heavy metals and metal vapors... this exhaust gas isn't healthy for living organisms, even algae. That's why we call it pollution. It's not the ideal breeding ground for algae: it's as hot as a furnace, there's no sunlight, and there are numerous chemical toxins contaminating the "fresh breathable CO₂" that algae and plants crave.

Capturing carbon dioxide isn't sufficient. Trees, algae, and plants outside the car will capture that carbon anyway, once it's in the atmosphere: you don't need a special tube on your car for that. But capturing carbon with plants isn't carbon-neutral over the fossil fuel life-cycle unless you put the carbon back under ground. It's not even clear to me that carbon neutral policy is good for the planet; and this algae tube isn't even carbon neutral.

What effect does this tube have on engine performance, auto maintenance, and gas mileage? Adding exhaust backpressure increases engine temperature and lowers performance. Users may burn more gas, less efficiently, getting fewer miles per gallon, because their exhaust system is essentially clogged. Engine life may be reduced. This data should be trivially easy to collect by road testing.

The entrepreneurs claim to have filed for tax credits and other incentives. Anyone can ask the EPA to evaluate technology; that doesn't mean the EPA will evaluate it; and it certainly doesn't mean that a tax credit is "in the works." If these guys had a real and competitive idea, why haven't they applied for an SBIR? What's their DOE project number? Or did they prefer Kickstarter over these real methods to fund environmentally-friendly energy technology because Kickstarter requires far less accountability?

Our OP asks if this is a scam. At first glance, I thought otherwise: it looked like some naive high-schoolers optimistic about ecologically friendly technology innovation, who haven't yet learned very much about biology, chemistry, physics, engineering, and the environment. Given enough time, working out the details on their own, plus a healthy amount of formal schooling, they'll learn to constrain their problem a little better, and make more realistic claims.

But the more I looked at their elaborate diagrams, drawings, and photos; and the more I entertained their outrageous claims; I realized they've put too much effort into their charlatanism to have overlooked the basic operational flaws. Airflow simulations? Computational fluid dynamics? All the while ignoring basic physics and chemistry? I conclude that there is no plausible way these guys are "unaware." One cannot operate a CFD software program if one does not know how to use a 4-function calculator. They know exactly how ineffectual their device is, in concept and in practice. They see crowd-sourced internet funding as an easy way to get twenty thousand dollars with few questions and zero accountability. Perhaps it is an indictment of the recent fad for "crowd sourced funding" - uninformed public contributors are very ill-equipped to evaluate the financial and technical merits of new ideas. And, these guys are taking full advantage of it. Perhaps they are not even who they claim to be, but chose the façade of independent kid-inventors to maximize marketability in the target audience.

The real trouble is, disproving the device requires a little more lab equipment than their average clientele will muster; there's a vibrant commercial market for all sorts of pseudoscientific cruft, because someone always buys it. Nimur (talk) 02:54, 2 August 2013 (UTC)

Thanks guys, That's all pretty much what I thought, but the presentation, and the complete lack of any skepticism from media that covered it gave me he tiniest shade of doubt that I was missing something obvious. I must be getting gullible or something!
Still, you have to respect a well formed scam. I wonder if they'll even bother shipping out product, or if they'll just disappear entirely. APL (talk) 05:55, 2 August 2013 (UTC)

Well, let's ask the inventors! There is a new post on the comments section at the kickstarter that asks some of these questions - it's written by a guy called 3DGeek who pledged $1 in support of this "amazing" invention. I'm guessing that he'll back out his pledge unless he gets some convincing answers. Interestingly, I used to use "3DGeek" as my online handle...quite a coincidence! Perhaps some more people would like to risk $1 to ask the inventors of this wonderful machine some clarifying questions? (Note that you can always revert your pledge before the Kickstarter ends if you don't get any decent answers!) SteveBaker (talk) 14:54, 2 August 2013 (UTC)

August 2

protect US electrical grid

How important is it to protect the US electrical grid from electro-magnetic pulses and solar flares? There are people saying that it can be done for a few billion dollars and should be done. Bubba73 ^{You talkin' to me?} 01:15, 2 August 2013 (UTC)

See One Second After. I think chances are 50/50 this will get me, and higher I'll get a bureaucrat myself if it do. μηδείς (talk) 02:32, 2 August 2013 (UTC)

?? What dialect is your reply in, Medeis, and what does it mean? -- Jack of Oz ^{[pleasantries]} 03:55, 2 August 2013 (UTC)

How important to whom? Very important to the US, quite important in Europe, not at all important to certain other countries and regimes. See electromagnetic pulse and solar flare. The usual way to convince the taxpayers is to wait for something to go wrong, and then fix it.--Shantavira|^{feed me} 10:15, 2 August 2013 (UTC)

Important for the US, of course. A friend of mine saw someone on one of the CSPAN channels saying that we need to spend a few billion dollars to protect it. I don't know if he has legitimate concerns of wants to profit from it. Bubba73 ^{You talkin' to me?} 17:48, 2 August 2013 (UTC)

Things

Why so so many people online fight about whether Edison was cleverer / more significant than Tesla? 105.236.159.229 (talk) 11:49, 2 August 2013 (UTC)

People love to argue about all sorts of things - Android versus Apple, Mac versus PC, dogs versus cats, classic StarTrek versus STTNG (versus Voyager (versus Star Wars)), Ferrari versus Lamborgini...you name it and there is a vigorous online debate about it. Edison and Tesla were rivals during their lives - they both did a bunch of crazy stuff, so it's easy to take sides. Tesla is a particularly good topic to rant about because he claimed to have done so many amazing things. We're 100% sure he didn't actually do all of the things he claimed - and 100% sure that he did do some of them. So there are large grey areas in his achievements that are great fodder for online flame-wars. Edison is also a great target because he had a great propensity for taking things invented by his employees and claiming that he, personally, invented them...so again - he's a great target for debate. SteveBaker (talk) 14:29, 2 August 2013 (UTC)

Of course the Star Trek/Star Wars arguments are kind of silly, given that Babylon 5 is so much better than either one. --Trovatore (talk) 02:41, 3 August 2013 (UTC)

Did you see Pawn Stars last night? Edison and Tesla started the argument. Bubba73 ^{You talkin' to me?} 21:34, 2 August 2013 (UTC)

Tesla was more of a "pure" scientist, and wasn't all that good at public relations (it can't be a coincidence that the typical "mad scientist" kinda looked like Tesla). Edison was more of a "practical" scientist, and was much better at P.R. AC won out over DC, but we don't call the power company "Commonwealth Tesla". Tesla teamed with George Westinghouse to get into the practical side, but Westinghouse is the name we remember. Tesla sued Marconi over the invention of radio, and eventually won the suit, but we associated radio with Marconi nonetheless. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:57, 2 August 2013 (UTC)

They both did great things in their youth, and then made completely untrue claims in their old age. By picking and choosing which part of their life you look at, or how much of their claims you believe you can make it look like either was "Better".

On top of that "Invention" rarely happens like it does in the movies. People incrementally improve existing ideas. To say that any single thing was wholly invented by any single person is misleading. So that gives you the perfect "ammunition" to discredit inventors you don't like by pointing out the earlier work that they built upon. (While ignoring the fact that your favorite inventor did the same thing!)

However, I think a lot of the current drama over the two inventors can be traced back to this very misleading infographic/comic from The Oatmeal.

APL (talk) 02:38, 3 August 2013 (UTC)

Loga

Why do dogs put their heads out the car window? 105.236.159.229 (talk) 11:58, 2 August 2013 (UTC)

I don't think we know for sure - but it's clear that the wind in their faces is enjoyable. I kinda suspect that they also like that smells are zipping past with incredible rapidity so they get the same experience of speed that humans get from looking out of the window. SteveBaker (talk) 14:22, 2 August 2013 (UTC)

This source corroborates Steve's version. It's not a scientific publication, but some kind of dog behaviorist. According to it, apparently, dogs do not enjoy being blown on the face, and it's even detrimental to them. But since their sense of smell is complex and advanced, they are exposed to a plethora of sensations. OsmanRF34 (talk) 22:29, 2 August 2013 (UTC)

Heat screen

Can you have a sort of heat cream that blocks heat in the same way that sun screen blocks UV? — Preceding unsigned comment added by 188.76.169.87 (talk) 12:16, 2 August 2013 (UTC)

Heat arrives by several mechanisms - conduction from the air in the environment and IR radiation from other hot objects (such as the sun) being the most obvious. You could perhaps design some kind of cream that reflects IR light away from you - but you'd still get hot from conduction from the atmosphere. You could certainly make something that evaporates like natural sweat to cool the body for a while - but it would dry out fairly quickly - so you'd need to re-apply it. In a sense, we already have this substance...just wipe your skin with a cloth soaked in plain old water - and you'll feel cooler...so obviously this is possible. SteveBaker (talk) 14:20, 2 August 2013 (UTC)

Could more co2 be good for the planet?

Without questioning global warming or that it's man-made, could we discuss whether it's a good thing? Who said that present or past levels of co2 are better than future higher levels? Who said that present or past temperature is better than a future higher level? — Preceding unsigned comment added by 188.76.169.87 (talk) 12:21, 2 August 2013 (UTC)

Well, it all depends on what you mean by "good" and "better". How do you measure "good" ? Good for who ? Our article on the economic impacts of climate change contains some possible answers. Broadly speaking, there is agreement that global warming will have economic costs, but there is disagreement over whether these costs could be catastrophic; whether they could be significant but manageable; or even whether they could be marginal compared to the long-term benefits of global industrialisation. Of course, if you are living on a small flat island a few metres above sea level, this debate must all seem very academic. Gandalf61 (talk) 12:49, 2 August 2013 (UTC)

Ok, good for nature, in the sense there's more of it. Or even agriculture, in the sense that we can produce more, maybe because there's more rain or a bigger area where we can plant. I suppose that many human communities will have to be re-located, which is not a big drama as such, since humans have always migrated. — Preceding unsigned comment added by 188.76.169.87 (talk) 12:54, 2 August 2013 (UTC)

There is lots of detail about agriculttural impacts in our artcile on climate change and agriculture. Headlines are a low to moderate degree of global warming is likely to increase food production in some parts of Asia and North America, but decrease it in the rest of the world. Gandalf61 (talk) 13:08, 2 August 2013 (UTC)

For more specific research, you may be interested in reading about SoyFACE [5]. Their research has identified many problems with growing crops in the midwest USA under higher CO_2 levels. One I found interesting: soy plants do grow a little faster, but their CN ratio also changes, and they end up getting more beetle damage. So the net result is still a negative impact on crop yields. SemanticMantis (talk) 13:10, 2 August 2013 (UTC)

Definitely NOT good for nature. Increased temperatures force plants and animals to migrate towards the poles - but the timescales of this change are too short for plants to spread very far - and much too fast for animals to evolve. I was listening to a report just a few days ago that trees that are normally resistant to forest fires in the south-western part of the USA are becoming less resistant because of climate change - and the overall increase in temperatures makes forest fires much more likely. The consequence of that will be the eradication of large forests in those regions. The trees don't have time to re-seed themselves further and further north because it takes 30 years to grow a tree - and each one can only travel a dozen feet from it's parent. At that rate of movement, these plants can't possibly outrun the effects of climate change - and face extinction.

This isn't good for humans either. If nature suffers - so will we. It's possible that human activity such as farming can move further away from the equator - but because our society has strict national boundaries - this will be disasterous for some countries and a win for others. The stresses that causes will result in international tensions - wars and other very bad things.

The idea that crops will do better because of increased CO2 levels is true for some species - but it's also true for some invasive species, native weeds and many diseases of plants - so it might be that our farmlands become overwhelmed by disease and non-productive species.

Truly, the result of this will be a massive loss of bio-diversity - and that cannot be good for mankind or "nature".

SteveBaker (talk) 14:14, 2 August 2013 (UTC)

In the long run the Earth can survive a lot, and what is "good" is quite mysterious. But in the short term any change is bad change. For example, if you lived on the Grand Banks 8000 years ago, the rising sea level would be a big problem. Return of the ice age would be a big problem. As in that example, sometimes there is actually no way for climate not to change (either sea level must rise or the ice age must return) but it still sucks! In our case though, we're shooting extra holes in the bottom of the boat. Wnt (talk) 14:57, 2 August 2013 (UTC)

It doesn't make sense to ask what's "good for" the earth. It only makes sense to ask what's "good" for us, or for some category of life. If the asteroid hadn't hit the earth, maybe the dinosaurs would have continued to flourish a lot longer, and would have eaten up all of our biological ancestors. So that event was bad for the dinosaurs, good for us, and neither good nor bad for the earth, as the earth is just an object. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:26, 2 August 2013 (UTC)

Yes, if you do not count life forms as a part of the planet - that's true. Even life itself will probably continue flourish despite what mankind is doing here...but you might end up with oceans containing nothing but algae and jellyfish and land containing nothing but fire-ants and cacti. In time (just as after the other mass-extinction events) new species will evolve and the world will carry on - albeit in a different direction. Individual humans may not see a significant degradation in quality of life during their lifetimes - but each generation may have slightly harder lives than the previous. So any consideration of "better" and "worse" has to be made relative to what we, as humans and as a species, consider good and bad for the future survival of our genetic heritage. SteveBaker (talk) 17:27, 2 August 2013 (UTC)

In the very long term, isn't the occasional mass die-off a driving factor of evolution? With more complicated and "Advanced" species emerging after the die-off?

Not that I'd personally want to be one of the ones who die off, but if I were an immortal god, it might be interesting to roll the dice and see if something better than humanity crops up in the million years after an ecological disaster. APL (talk) 02:26, 3 August 2013 (UTC)

• The climate change problem arises not so much because more CO2 would be bad per se, as because of the extremely rapid rate of change. Ecosystems in many places just can't adapt fast enough to keep up with the rate of warming. If we had been living in a world of 500 ppm CO2 for millions of years, our geographic distribution would be adapted to it, and we would not see it as a problem. Looie496 (talk) 17:32, 2 August 2013 (UTC)

The sheer number of humans on the planet is currently causing a major extinction event anyhow. Pumping huge amounts of carbon dioxide into the air and making life even more difficult for anything else is just one amongst loads of other things we're doing. We've parks to conserve some species we've taken a fancy to, they will die because they can't move. Dmcq (talk) 19:41, 2 August 2013 (UTC)

Hominids have been extinguishing species and altering the environment from the time they learned to hunt, build fires, grow crops, etc. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:54, 2 August 2013 (UTC)

Medicine package US and Europe

Why? In the US they seem to prefer a plastic jar, and in Europe they seem to prefer all pills packed individually. — Preceding unsigned comment added by 188.76.169.87 (talk) 13:11, 2 August 2013 (UTC)

Pressurize

is it necessary to pressurize gas before burining.? give any referencve... — Preceding unsigned comment added by 175.101.60.14 (talk) 14:20, 2 August 2013 (UTC)

No, as pranksters with their acetoxy balloons can attest. But I wonder what the lowest possible pressure for a "rapid burning" reaction in a room temperature gas would be (I fear creativity about the definition of burning might obscure the answer) Wnt (talk) 14:53, 2 August 2013 (UTC)

No, but its way more effective to handle and transport that way. --Kharon (talk) 15:37, 2 August 2013 (UTC)

Not at all. The hydrogen pop test relies on the flammability of freshly prepared hydrogen gas at room temperature and pressure. Fuel-air explosives burn gases like ethylene oxide at atmospheric pressure with devestating effect. 202.155.85.18 (talk) 03:34, 3 August 2013 (UTC)

Vitamin overdose

Can you die from a vitamin overdose? How many multivitamins or vitamin E or vitamin b6 tablets would you need? Pubserv (talk) 18:07, 2 August 2013 (UTC)

Yes - see Hypervitaminosis A (and Vitamin poisoning, though that doesn't mention any fatalities). AndrewWTaylor (talk) 18:10, 2 August 2013 (UTC)

How many multivitamins or vitamin E or vitamin b6 tablets would you need? Pubserv (talk) 19:35, 2 August 2013 (UTC)

For vitamin A, Hypervitaminosis A#Pathophysiology says that 21,600 IU per day over an extended period can cause problems, while a portion of a polar bear liver can kill you in a single dose. Hypervitaminosis E gives a safe limit of 1500 IU per day. The B vitamins are water-soluble, so they don't build up over time the way the fat-soluble vitamins do; B vitamins gives an upper intake limit of 100mg of B6. --Carnildo (talk) 01:12, 3 August 2013 (UTC)

Xavier Mertz may have died of vitamin A poisoning - see the article on Douglas Mawson --TrogWoolley (talk) 18:18, 2 August 2013 (UTC)

Soluble medication pills.

When they dissolve in the mouth, do they begin to enter the body/bloodstream in the mouth, or does it happen afterwards/only in the stomach? Pubserv (talk) 19:32, 2 August 2013 (UTC)

This will vary with the type of medication. Some are absorbed quickly through the mouth (see Sublingual administration), whilst others are absorbed much more slowly through the stomach. Dbfirs 19:48, 2 August 2013 (UTC)

What is the case with Zyprexa soluble pills? Pubserv (talk) 20:02, 2 August 2013 (UTC)

The active component of Zyprexa is almost insoluble in water. Maybe some people smash the pills and mix with water, but unless it was prescribed to be taken like that, no one should do. OsmanRF34 (talk) 22:37, 2 August 2013 (UTC)

Medicine without side effects.

Why can't we make medicine/drugs WITHOUT side effects? Pubserv (talk) 19:34, 2 August 2013 (UTC)

Because a side effect is just an effect we don't want, and we want our medication to be effective. If a medication doesn't have an effect, it's not a medication, it's inert. And if it has an effect (which it does by definition), there will be circumstances in which that effect is undesired, or a side effect. Most substances have multiple effects, of course, which, along with the problem of different substances affecting different people in different ways under different circumstances, provides a fuller answer to you question. - Nunh-huh 20:05, 2 August 2013 (UTC)

I find the legs on tables annoying. They get in the way. Why can't you design a table without any legs? Now there's a nice straightforward problem, it can't be anywhere near as hard as making drugs without side effects. Dmcq (talk) 20:14, 2 August 2013 (UTC)

"Medicines" without side effects already exist. Most homeopathic preparations fit that bill. Problem is they don't have any desirable effects, either. Dominus Vobisdu (talk) 20:21, 2 August 2013 (UTC)

They do have one effect: As a diuretic on your bank account. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:50, 2 August 2013 (UTC)

You can hang a table. Not sure if it technically stops being a "table", but you can still put chairs around it and eat. Might have to worry about your elbows banging chains instead of knees banging legs, but it solves the underlying problem. Drugs, yeah, much harder. No clue. InedibleHulk (talk) 06:18, August 3, 2013 (UTC)

Even oxygen has side-effect (that is, undesirable effects). It comes down to the fact that we are complex systems. But nature chose to re-use the same components in different body parts. You'll find the same protein, neurotransmitter, hormone in different parts, fulfilling a different function.

Aspirins, for example, prevents blood clots because they inhibit a certain group of enzymes in platelets. However, these same enzymes are also in the stomach lining and serve to protect it against acids. Aspirin cannot distinguish between them and so while it prevents clots, it also destructs the protection of the stomach lining leading to ulceration.

On a bright side, science strives to develop more target drugs.

For example II: histamine. It regulates sleep and wakefulness, but also your autoimmune system. An antihistamines would affect both processes, however, chemists were able to discover new antihistamines that bind to one specific histamine receptors, the one that regulate allergic responses. These antihistamines are present in allergy medicines that won't make you drowsy.OsmanRF34 (talk) 22:55, 2 August 2013 (UTC)

August 3

Crescent Moon illumination

I was just watching the crescent Moon (it's about an hour before sunrise here), and I noticed that, while I could see the sunlit crescent, I could easily see the dark part of the Moon as well. The thing is, the edge of the Moon on the dark, non-lit part seemed to be brighter than the center. Is it due to the Moon geography (lighter/darker parts), or due to some real effect? Thanks 208.80.154.136 (talk) 02:25, 3 August 2013 (UTC)

I think most likely what you are seeing is Mach bands (an optical effect). Looie496 (talk) 02:31, 3 August 2013 (UTC)

Yeah - I second that - it's a classic example of a mach band...essentially just an optical illusion. SteveBaker (talk) 05:34, 3 August 2013 (UTC)

Airliner emergency exits

Every commercial airliner I've ever been on had emergency exits of some type with clear instructions on how to open the door in case of a crash. Usually, if you're sitting in an exit row, the hostesses even come and instruct you on how to open it in case the pictographs aren't clear. Do these emergency exits only open if the plane is stopped on the ground? Could criminals/terrorists open the doors in flight for bailing out, or just for the chaos caused by loosing cabin pressure? 202.155.85.18 (talk) 03:25, 3 August 2013 (UTC)

According to this, you can't open them while the cabin is pressurized since they have to swing in. Dismas|^(talk) 03:31, 3 August 2013 (UTC)

Some of the ones I've seen don't swing at all. Pulling the lever actually detaches the door like a manhole cover, and then you throw it outside the aircraft, so I don't think pressure will hold those on. 202.155.85.18 (talk) 03:43, 3 August 2013 (UTC)

Do they go straight out or do you have to pull them in and then push them out lengthwise? Dismas|^(talk) 04:07, 3 August 2013 (UTC)

I think they just fall outside, but my hostess on that flight was from Thailand so she spoke a bit funny and maybe they do come in first. Googling around a bit I found that a new trend it apparently outward swinging doors that avoid having to pull the door inward against a throng of desperate passengers in fear for the lives. These are locked electronically in a fail-open arrangment. 202.155.85.18 (talk) 04:38, 3 August 2013 (UTC)

These say there is no possibility of opening them in flight.[6] [7] Apteva (talk) 04:49, 3 August 2013 (UTC)

Where do kangaroos come from and what are they made of?

I don't mean Australia and meat, but in an evolution sense. Do we know what common grandparents they share with each of the mammals they sort of look like (goat, possum, human, rabbit, etc.)?

I've tried Googling, but only find archaeological and zoological stuff (I don't really trust those guys). I don't understand genetic terms enough to Google efficiently, but I can mostly understand them in context once I have them (same with French). A push in the right direction would be nice, if nobody has a definitive answer. InedibleHulk (talk) 06:12, August 3, 2013 (UTC)

What part of your brain is "You"?

Is there a section of your brain that contains nothing but your knowledge that you are you?