Wikipedia:Reference desk/Archives/Science/2009 February 14

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February 14

Questions about catnip

1. Is catnip an addictive substance (for cats)?

2. Is it possible for a cat to OD on catnip?

3. What recreational drug, when taken by a person would most closely mimic the psychoactive/physical effects of catnip on cats?

Just curious after watching videos of cats getting high on the stuff on YouTube. Thanks. --84.68.107.30 (talk) 00:27, 14 February 2009 (UTC)

1. catnip is not addictive

2. not by rolling in it or smelling it. If the cat eats too much catnip (some cats like to eat fresh catnip, mine does), it may become ill.

refs for these two answers: [1], [2]

3. hard to say, catnip affects different cats differently. Some get loopy, some get aggressive, some get a little sexual. I'd say marijuana, for its euphoric effect, but I don't know a lot of marijuana users that get hyper or aggressive. There's probably not a really analogous human drug. Alcohol is euphoric, but its effect lasts longer and it's addictive. - Nunh-huh 00:49, 14 February 2009 (UTC)

1 How would you define "addictive" in cats. I have had cats do serious damage to containers or cabinets to get at the stuff.

2 Some cats become over excited and can "conk out" from catnip. Others just get extremely tired in a hurry and wander off for a cat-nap. Reactions vary greatly between different cats. Lots of kittens and some older cats aren't affercted at all. BTW: I've seen several cats get the same reaction from elderberry.

3 Androstadienone and/or Musk probably come closest, although not in intensity. We haven't discovered a pheromone for humans that has that strong an effect (thank goodness). Maybe it's just that cats don't care about indulging. After all they are not the ones who have to go out and earn for the tuna cans. Mrrow. Also see [3] - 76.97.245.5 (talk) 02:26, 14 February 2009 (UTC)

Why do cats need a special definition of addiction? I suppose because of the muddled popular meaning of the word, we should specify that we're talking about physical dependency manifested by withdrawal symptoms or increased drug tolerance, and that catnip doesn't cause either. - Nunh-huh 03:17, 14 February 2009 (UTC)

Well caught I was thinking of the other use for psychological addiction. 76.97.245.5 (talk) 07:32, 14 February 2009 (UTC)

According to the second link above, "It is possible for cats to become immune to its effects if exposed too often". Or could it be the case that the regular dose just isn't enough to cause a high any more? How on earth do you determine if a cat is jonesing or not anyway? --Kurt Shaped Box (talk) 09:03, 14 February 2009 (UTC)

Reading a little about the effects of catnip and the short-lived - but seemingly intense high, it reminds me somewhat of the effect that freebasing crack has on a human... --Kurt Shaped Box (talk) 09:11, 14 February 2009 (UTC)

Neanderthals, Humans and Chimps

I was just reading the artical on the Neanderthal genome project. In the artical, there is reference to the Chimp's DNA being 18.77%98.77% identical to modern human DNA. What is it about the remaining 1.23% of the chimp's DNA that makes it impossible for humans and chimps to interbreed (aside from the ethical objections we may hae)? Could modern humans and neandertha;s inter-breed? —Preceding unsigned comment added by 209.161.215.58 (talk) 04:23, 14 February 2009 (UTC)

I'm not sure it's true that chimps and humans can't interbreed. It's not easy because we have one less chromosome than chimps. Two of the great-ape chromosomes are fused together in humans. So while most of the DNA is identical - the way it's glued together isn't. But that doesn't make it completely impossible. Humanzee explains all of the horrible details. It's widely assumed that humans and Neanderthals would have been able to interbreed. SteveBaker (talk) 04:33, 14 February 2009 (UTC)

The degree of identity between human and chimpanzee genomes is not easy to estimate. Figures like the one to which you refer ("98.77%") are fraught with serious problems, as discussed in many papers including this one [4]. The differences go much deeper. --Scray (talk) 05:03, 14 February 2009 (UTC)

Representing the similarity of genomes in term of percentages is very, very misleading. Yes, we share about 98.4% of our genome with chimps, but we also share about 90% with mice and 50% with bananas[5]. First, as mentioned above, percentages don't take into account structural chromosomal differences (fusions, inversions, and the like) that may exist, making interbreeding difficult or impossible even between otherwise closely related species. Second, there is a great deal more information in a genome than just the genes themselves. One major example would be how the genes themselves are regulated: how strongly they are expressed, in which tissues they are expressed, and when. Complicating things further, altering a single base may result in a major change in how the gene product itself functions. One gene often given credit for providing humans the ability of language is FOXP2, which contains 3633 bases in its coding regions. The human and chimp versions differ by only 3 (0.008%) of those bases. Clearly, when it comes to genetics, a little difference can go a long way. – ClockworkSoul 06:26, 14 February 2009 (UTC)

Despite what SteveBaker said, the question of wheather Humans and Neanderthals could interbreed is still an open one and the lack of evidence that any interbreeding took place may indicate that interbreeding was not possible. The only honest answer is that we don't really know yet. Dauto (talk) 18:42, 14 February 2009 (UTC)

Regardless of whether "modern" humans tens of thousands of years ago and neanderthals had viable offspring, there is no reason to believe they did not have sex. Modern humans have been known to have sex with sheep, cows, donkeys, horses, dogs, geese and chickens. Kinsey found that 8% of men and 3.6% of women reported such sexual relations with animals. It strains credulity that early humans and neanderthals never danced the horizontal bop. Edison (talk) 14:39, 15 February 2009 (UTC)

And goats. Don't forget the goat. Very important. BrainyBabe (talk) 15:47, 16 February 2009 (UTC)

So did the Sudanese man and his goat-wife have any kids? Edison (talk) 16:43, 17 February 2009 (UTC)

From what I've heard (which may be very incomplete), the only attempt to find surviving Neander genes was to look for N. mitochondria in a sample of modern humans. The negative result suggests that interbreeding was rare, but doesn't establish that it never happened: the female-line descendants could have died out by chance. (Many family names, i.e. someone's male-line descendants, have died out in the few centuries since they were adopted.) —Tamfang (talk) 18:17, 18 February 2009 (UTC)

Or not died out, but just become rare enough that none were present in the sample. (If only a few dozen or a few hundred existed, they would be unlikely to be found...) 128.194.250.39 (talk) 06:53, 19 February 2009 (UTC)

Scientific name

Does the scientific name Cacops aspidephorus mean "bad-face shield-bearer", or is there a more subtle meaning I may have missed? And, if so, why did Williston call this animal "bad-face"? Thanks a lot to anyone who can help. --83.57.77.67 (talk) 07:41, 14 February 2009 (UTC)

Our article on Dissorophidae (which is the family from which Cacops comes) says that all dissorophidae had armored plates over their spines...which explains "shield bearer"...and it says that Cacops is specifically known for having a "relatively huge head". I'm not sure that "bad-face" applies - but I wonder whether "big-face" might not be a better translation? (I long ago forgot any latin I might ever have been taught). It's also possible that the discoverer found this dissorophidae and found that it fitted in with other species in that family - except that the head didn't fit the pattern of the other species. I suppose it's then possible that the head/face was considered "bad" because of that failure to match the other species in that family. SteveBaker (talk) 02:42, 15 February 2009 (UTC)

Your Latin wouldn't help even if you could remember it Steve, I do believe that is Greek. Aspis=shield. The Latin for shield is scutum. SpinningSpark 15:08, 15 February 2009 (UTC)

Mental illness and "colorful" writing

A few questions ago, SteveBaker wrote "(You can tell it's a crackpot site because it's using LOTS of color/italics/underlining)", and I knew (even before I followed the link) exactly what he meant. I've noticed the phenomenon in web pages, I've noticed similar things in flat-text fora (e.g. Robert E. McElwaine's tendency to RANDOMLY capitalize WORDS...) and my father once told me that the American Institute of Physics used to have a special category for crackpot letters they received written with a variety of different-colored pens. My question is: is this writing quirk associated with any particular mental illness? I'd think it would be a symptom of schizophrenia and/or thought disorder, but I haven't seen it actually listed as such. -- Speaker to Lampposts (talk) 09:12, 14 February 2009 (UTC)

I guess emphasis ("shout when argument is weak") takes all forms but you might be interested in the article about green inkers. Another tic is to pad out a erm, "certain articles" with excessive C-quotes. Julia Rossi (talk) 09:16, 14 February 2009 (UTC)

It seems to be quite common on Usenet for the crackpots to pad out their posts (often several, one after the other, crossposted, saying pretty much the same thing, as is the custom) with weblinks and random cut+pasted excerpts from websites which are seemingly unrelated to the topic of the screed. --Kurt Shaped Box (talk) 09:32, 14 February 2009 (UTC)

The best crackpot site of all time has to be Time Cube. A Quest For Knowledge (talk) 11:19, 14 February 2009 (UTC)

I second that. -Pete5x5 (talk) 01:16, 15 February 2009 (UTC)

Closely followed, of course, by stopabductions.com, a website claiming that telepathic aliens can be thwarted through the use of a telepathy-blocking helmet... *ahem* this is a quote from their testimonials section:

“I am happy to report that the Thought Screen Helmet has been performing beautifully! It’s been over six months now and NOT ONE INCIDENT! Aside from some of the naive neighborhood kids and their taunting it’s been a blissful period.”

This. Is. Insane. Also: see aliensandchildren.org , another (equally ridiculous) site run by the same person. Ilikefood (talk) 23:01, 20 February 2009 (UTC)

Alex Chiu and the 'Anus 100' guy deserve honourable mentions for their incomprehensibility and sheer dogged determination to defend their theories in the face of overwhelming criticism and ridicule. --Kurt Shaped Box (talk) 11:58, 14 February 2009 (UTC)

At first I thought you meant Frank Chu, with whom I've futilely attempted conversation. —Tamfang (talk) 18:22, 18 February 2009 (UTC)

Immortality devices! LOL. I love it! (Those are sentences that deserve exclamation points.) A Quest For Knowledge (talk) 17:37, 14 February 2009 (UTC)

I remembered the anus guy's name now, FWIW. Hiroyuki Nishigaki. Check out some of his musings/ramblings if you can find them online (his website seems to have gone now). His main theory (from what I could understand of it) combined 100-times-daily anal constriction with various other religious, spiritual, alien, pseudo-scientific or downright crackpot concepts to produce a truly (sometimes literally) incoherent wholeness. IIRC, he was also trying to encourage mentally ill people to stop taking their meds on Usenet - which would've been dangerous, if the guy didn't come across as *more* insane than everyone else there present. --Kurt Shaped Box (talk) 22:21, 14 February 2009 (UTC)

Children also tend to randomly write in multiple colors, so I associate that with "immaturity". There are places where color is used to actually mean something, though, like Bibles which use red text for supposed quotes from Jesus. StuRat (talk) 14:27, 14 February 2009 (UTC)

Ding! Ding! We have our explanation! --Kurt Shaped Box (talk) 22:07, 14 February 2009 (UTC)

And don't forget about exclamation marks ! Every sentence should end in at least one, no matter how dull ! It is now 9:30 AM ! And, when the reader gets used to every sentence ending in an exclamation mark, it's time to escalate to several !!!!!!!!! StuRat (talk) 14:31, 14 February 2009 (UTC)

When I was a lad, many of the newspaper comic strips ended every sentence (except questions) with a bang. Is that still true of any? —Tamfang (talk) 18:34, 18 February 2009 (UTC)

This will go way over your head as my research into this area is decades past general scientific understanding (let alone that of lay people) but here goes: the reason crackpots write with different colors is because they are approaching science with their right brain hemisphere. It is also the reason they fixate on the intuitive meaning of scientific terms (i.e. the impression the term would make before you ever learn what it means), with a seeming inability to internalize the technical definition. This is a style of thinking -- its more useful in some areas of life and science and less useful in others. That's all I will say, because my research on this subject is so far ahead of science that trying to explain it to you in a Reference Desk response would be hopelessly quixotic. —Preceding unsigned comment added by 82.120.236.246 (talk) 15:22, 14 February 2009 (UTC)

Come on, everyone knows any sentence containing the phrase "far ahead of science" HAS to end with an exclamation mark! --Tango (talk) 15:39, 14 February 2009 (UTC)

Then I would have had to say "the reason crackpots write with different colors is because we are approaching science with..." —Preceding unsigned comment added by 82.120.236.246 (talk) 15:53, 14 February 2009 (UTC)

I don't know why they do this - but it's a dead giveaway when you open a web page that looks like that. As for excessive exclamation marks, it helps to pretend that each "!" is really a "?". I doubt that this is a mental illness per-se - but there is certainly a correlation between crackpot theories and tasteless web sites. However - correlation is not causation. SteveBaker (talk) 19:22, 14 February 2009 (UTC)

I guess that depends on whether you count being a complete idiot as a form of mental illness. I've never been quite sure how you distinguish between "learning difficulties" and "stupidity". In cases where there is a definite cause for the learning difficulties, it's pretty simple, but in other cases I'm not sure there actually is a distinction. --Tango (talk) 20:07, 14 February 2009 (UTC)

Another common 'red flag' for these quacksites seems to be the overuse of mid-90s-web-style animated gifs and stock clipart. Has anyone else ever noticed that? --Kurt Shaped Box (talk) 22:38, 14 February 2009 (UTC)

Pretty much everything about their webpages boils down to them being stuck in the mid-90s (you forget to mention <blink> and <marquee> tags!). I have no idea why... --Tango (talk) 23:25, 14 February 2009 (UTC)

They like <center> tags too. SteveBaker (talk) 23:45, 14 February 2009 (UTC)

The use of several different fonts, bold/italic styles and text sizes within the same paragraph/block of text too. I wonder if they're deliberately trying to give the impression to their readers that they were chewing the keyboard when working on the site? --Kurt Shaped Box (talk) 00:44, 15 February 2009 (UTC)

Another dead giveaway to me for a crackpot letter is its ending. It's usually "Think about it!"

Think about it!. Bunthorne (talk) 21:48, 14 February 2009 (UTC)

Thought-terminating cliché#Non-political examples. Most of these websites will also have a colourful array of fallacies within them (no pun intended). --Mark PEA (talk) 12:29, 15 February 2009 (UTC)

Yes, such as circular logic. The reason that circular logic tells us these sites are run by crackpots is that, as previously established, circular logic tells us these sites are run by crackpots. StuRat (talk) 17:31, 15 February 2009 (UTC)

I guess you are arguing that there is no evidence that the sites are run by crackpots, but the definition of crackpot could be "someone who uses colourful writing and talks crap", which would mean it is not circular logic. Although hasty generalization is still possible. --Mark PEA (talk) 18:28, 15 February 2009 (UTC)

Is there any way to repair a cracked DVD?

I have a dual-layer DVD-Video disc with a full-thickness crack running from the centre, to about 1cm into the data area. Is there any possible way that I could either fix the disc, or even just render it readable for long enough for me to make a copy?

I guess that the answer's going to be 'no' - but hey, it's worth a try if it saves me having to buy the movie again... ;) --Kurt Shaped Box (talk) 13:04, 14 February 2009 (UTC)

If it's full-thickness, then probably not (surface scratches are another matter). Almost certainly not easily (you might be able to pay a specialist company lots of money to get the data off, like you can with broken hard drives, but I doubt that's worth it). You might be able to get the DVD replaced for free (or maybe for a small admin/p&p fee) from the manufacturer, though - if all the DRM and EULA stuff is to be believed, what you bought wasn't the DVD but rather a license to the content that is on the DVD, so it makes absolutely no sense for them to charge you for the content again just to replace the DVD (of course, sense doesn't really come into it!). Try asking at wherever you bought it. --Tango (talk) 13:12, 14 February 2009 (UTC)

I wouldn't count on them replacing it for free. They conveniently either say you are buying the disc or the content on it, whichever way will get them the most money. Can we get free DVDs by turning in old VHS tapes ? I doubt it. StuRat (talk) 14:22, 14 February 2009 (UTC)

DVDs usually contain additional content that wasn't on the VHS version, so almost certainly not. --Tango (talk) 15:45, 14 February 2009 (UTC)

Even if it isn't, the idea that the content and the medium are totally separable is certainly not part of the EULAs. --98.217.14.211 (talk) 00:39, 15 February 2009 (UTC)

As for the original Q, I'd guess that there is some way you could "fix" the DVD. By this I mean glue it together so it won't fall apart when played. However, the data in the vicinity of the crack will still be lost. This is merely annoying for music and video, but will make any program on the disk completely unusable. StuRat (talk) 14:22, 14 February 2009 (UTC)

It may be worth writing to the publisher. I did this once with a similarly damaged CD and they replaced it for the cost of postage after I had sent them the damaged original. -- SGBailey (talk) 18:41, 14 February 2009 (UTC)

There's some stuff you can buy to repair plastic eyeglass lenses that might work to repair the plastic part. The data as Stu said is another matter. Try opticians for the chemical (comes in a very small tube.) I came across it once and stocked up. I haven't seen it since. 76.97.245.5 (talk) 22:36, 14 February 2009 (UTC)

Have you tried playing it? DVDs have a lot of error correction and it may still be playable. In that case (if you can break the copy protection, which is possible) you could copy it to a new disc. --Chetvorno^TALK 07:49, 15 February 2009 (UTC)

Let me say right off that there is no way you'll be able to 'repair' the disk. Forget it - it's not gonna happen. Even if it did work, the extra weight of the glue on one side and not the other would unbalance the drive and either prevent it from playing or damage the bearings in the DVD drive. However, I would expect the error correction systems to be able to recover data from the DVD so it should play OK providing that's the only damage. If it also has some fine scratches, dust or fingerprints then there may just be too many errors for it to recover from. But there is another problem. A crack that goes all the way through the disk will have a very good chance of spreading and eventually causing the DVD to shatter while it's spinning. I would STRONGLY advise against playing it in a computer DVD drive because those can spin a lot faster than a Video-only DVD player and if a DVD comes apart at high RPM, it can do some serious damage. (I refer you to a Mythbusters episode where they tried playing various optical disks to make them fly apart). The trouble is that the other advice I'd like to offer would be to suggest 'ripping' the movie off of the DVD and writing it onto a blank disk using your computer...but with the risk of the disk shattering when you do that...I'm beginning to think that this is actually a bad idea. IMHO, you should first contact the company that made the disk and ask for a replacement. I think they'll probably give it to you - although they might want to charge for shipping & handling. SteveBaker (talk) 17:00, 15 February 2009 (UTC)

so cola is TERRIBLE for your teeth. Does swishing with water immediately afterwards help?

I heard cola is terrible, horrible for your teeth. Drinking thru a straw helps, but I wonder: would swishing your mouth thoroughly with clear water immediately afterwards also help any? I am not asking for medical advice! —Preceding unsigned comment added by 82.120.236.246 (talk) 15:09, 14 February 2009 (UTC)

Saying "I am not asking for medical advice" doesn't make it true. This is quite obviously a request for medical advice. Ask a dentist. --Tango (talk) 15:43, 14 February 2009 (UTC)

Yes, actually, it does -- saying, in bold, "I'm not asking for medical advice" means I'm not asking for medical advice. —Preceding unsigned comment added by 82.120.236.246 (talk) 15:53, 14 February 2009 (UTC)

No, it doesn't. You're asking for something which requires expert medical understanding and could easily lead you to behaviors which are not safe. Appending a contradictory statement to the end of it doesn't change that fact. It just makes your bolded statement false. --98.217.14.211 (talk) 00:42, 15 February 2009 (UTC)

Cola is no worse for your teeth than other soft drinks. For healthy teeth it's best to avoid drinks with added sugar. Rinsing your mouth thoroughly might remove some of the sugar.--Shantavira|^{feed me} 16:03, 14 February 2009 (UTC)

The carbonic acid, citric acid and phosphoric acid isn't good for them. There are plenty of soft drinks that aren't anywhere near as acidic. There are also plenty of soft drinks that aren't high in sugar. --Tango (talk) 16:30, 14 February 2009 (UTC)

Then what are you doing? --Tango (talk) 16:26, 14 February 2009 (UTC)

This possibly? SpinningSpark 16:33, 14 February 2009 (UTC)

Aside from everything else: Drinking through a straw WILL NOT AFFECT chemical or biochemical behaviour of a substance! That is a very frequent misinformation. (Assuming you arent drinking harzardous chemicals which actually react with the plastic) --91.6.7.232 (talk) 17:58, 16 February 2009 (UTC)

Don't be silly. Drinking through the straw isn't supposed to chemically change the drink. No one in the world believes that. The point is to stop the soda from repeatedly eroding your front teeth.

Who knows how much difference that makes, but some dentists seem to believe that it is significant. 21:10, 17 February 2009 (UTC)

Verifying that a CO detector works

Is there an easy and safe way to verify the correct functioning of a CO detector? --173.49.17.152 (talk) 19:33, 14 February 2009 (UTC)

Does it have a "test" button? That will verify that the batteries aren't flat. As for verifying that it actually detects CO, I'm not sure... you could try holding it up to your car's exhaust pipe while it's running (outside, otherwise you'll end up giving yourself CO poisoning while testing your CO detector, and that would just be silly!). But really, I think if you have reason to doubt your CO detector is working, you should just get a new one. It's not worth the risk. --Tango (talk) 20:05, 14 February 2009 (UTC)

That, of course, would be the easy answer. From what I understand, CO detectors have a finite lifetime, but some fail earlier than others. Although early replacement would be a (somewhat expensive) solution, it would still be nice to be able to verify that a CO detector is actually working even when its age suggests that it should. Like you pointed out, the test button merely tells you that the battery is not dead. With a smoke detector, you can use a smoke pencil to verify that it does detect smoke. I was hoping that there's a similar solution for CO detectors. --173.49.17.152 (talk) 20:23, 14 February 2009 (UTC)

Some CO detectors have self-diagnostic modes which give a more detailed test than simply "is the battery ok". For example, some have a test involving lighting a cigarette near to it, while in the test mode. The instructions supplied with the detector will have further information. DuncanHill (talk) 20:34, 14 February 2009 (UTC)

If you have cigarettes around, you probably don't need the detector to know you're getting too much CO. What are normal people supposed to do? Run out and buy cigarettes just to test the detector? --Trovatore (talk) 21:35, 14 February 2009 (UTC)

Normal people already have cigarettes available, we just prefer not to waste them testing electronic equipment! DuncanHill (talk) 21:38, 14 February 2009 (UTC)

Ah, read the manual... Can we pretend that my first recommendation? --Tango (talk) 20:36, 14 February 2009 (UTC)

(ec) There may well be, I don't really know how CO detectors work (although, knowing me, I will now compulsively find out!). I do, however, know how nasty CO poisoning is, which I why in the absence of a definite answer to a contrary my advice is to risk wasting money rather than risk wasting your haemoglobin. --Tango (talk) 20:36, 14 February 2009 (UTC)

I could be wrong but I'm doubtful that any manufacturer (at least in any country with strong and enforced consumer protections) would give device intended to be life-saving a lifespan that's likely to result in a substanial number of devices 'expiring' before then. In other words, if the manufacturer says you should replace the device in 6 years (random guess) only a tiny number of devices are likely to fail before then (and it not be detected by the self diagnostics). So it's not so much replacing the device early as on time Nil Einne (talk) 05:08, 15 February 2009 (UTC)

Try a smoldering incense stick. This will work for smoke detectors too. If it sounds the alarm, OK. If it doesn't, the stick is either not emitting enough CO or the detector is not working. A smoldering incense stick is also useful for revealing drafts, and does not leave the unpleasant smell of a cigarette. Check ebay for sources of incense. – GlowWorm. —Preceding unsigned comment added by 98.17.32.201 (talk) 23:46, 14 February 2009 (UTC)

Or ask your friendly neighborhood pyromaniac for assorted substances of ambiguous legality :-P Ilikefood (talk) 23:03, 20 February 2009 (UTC)

Mysterious Dead

Recently someone, who in turn got it from anonymous source, sent me a photograph of a dead animal that seems to be something between a bear and a dog. I could not find any refernece on Wiki. I have verified that actually the picture comes from a blog, but that damned blog has only pic and no explanation. Since I do not have the copyright and don't know who the author is, I cannot put it on Wiki. Instead I am putting it on my website : http://www.khurmi.com/sqyy.jpg. Courageous Wikipedias are urged to have a look at it and tell me what the hell it is. Please reply on my talk page.  Jon Ascton  (talk) 21:45, 14 February 2009 (UTC)

We'll reply here, we always do. --Tango (talk) 21:47, 14 February 2009 (UTC)

It's not a great picture, most of the nose is covered by grass, which doesn't help. It looks like a dog to me, though (probably an unusual crossbreed). --Tango (talk) 21:48, 14 February 2009 (UTC)

Looks like a black Chow-Chow mix. Compare [6]. Poor dog. 76.97.245.5 (talk) 22:25, 14 February 2009 (UTC)

(For some reason, the OP deleted this question and all of it's answers. Please don't do that.) SteveBaker (talk) 23:40, 14 February 2009 (UTC)

Whatever it is, it's been photoshopped pretty significantly. If you zoom in on the thin blades of grass over the animal's head, you can see that quite clearly. All bets are off. It could be anything - or nothing. SteveBaker (talk) 23:33, 14 February 2009 (UTC)

I don't see it... what am I looking for? --Tango (talk) 00:07, 15 February 2009 (UTC)

I don't see anything like canine teeth. And it's blue?? Cuddlyable3 (talk) 00:12, 15 February 2009 (UTC)

It's not just that - but look at the 'specular' highlight on the animals' black nose...the reflection is blue...it should be white. If you blow up the region around the grass blades, there are whole pixels of green and whole pixels of blue - and other than the color bloom that's caused by JPEG encoding, there is no soft average of grass-color and fur-color. There is no camera data in the EXIF data. It's eyes are blue too...it's a crappy photoshop job - it just screams it. SteveBaker (talk) 01:49, 15 February 2009 (UTC)

That's not a crappy Photoshop job. This is a crappy Photoshop job. The image under discussion is either a pretty good Photoshop job or real. The blue tint is presumably due to poor color balance in the camera, which has no analogue in computer graphics—and anyway, the light on the nose looks more diffuse than specular to me. The image was clearly cropped and probably resized (I don't think any digital camera takes photos in that aspect ratio), which would explain the lack of EXIF data. The green-blue boundaries don't look suspicious to me. Read the story of the Lumber Car as a cautionary tale. It looks implausible on the face of it, so people pore over the image for evidence of Photoshopping, and they find it, because most images of this (rather poor) quality have features that can be ambiguously interpreted as Photoshopped. That way lies conspiracy-theorist madness. -- BenRG (talk) 15:23, 15 February 2009 (UTC)

I've seen the 'lumber car' pictures before - they didn't strike me as photoshopped at the time - and it's good to hear that they were genuine. In order to discover whether an image might have been tampered with, you have to look at the subtle signs of color, lighting, shadows, etc. Those are all as they should be in the lumber car picture - but they most certainly AREN'T right in this one. SteveBaker (talk) 16:48, 15 February 2009 (UTC)

Diffuse light takes on the color of the object (which in the case of the nose - is black) and reflects more or less equally in all directions - specular light is constrained to a region where the angle of the incident light is roughly the same as the angle of the camera to the object. In this case, the parts of the nose that are angled away from us are black - so there is little if any diffuse reflection going on - the bright spot is therefore a SPECULAR glint. Specular reflections take on the color of the light source (which would have to be blue in order to make a blue splotch on a black object). The only way a 'shiney' spot on a black object could be blue would be if the photograph was taken in blue light - or if the camera was not registering red and green very well. However, the grass is green and there are other white things in the scene - ergo neither the light nor the camera was favoring green. It WAS tampered with. If there was excessive blue balance in the camera then you'd wouldn't have such bright green grass. I have some considerable experience with computer graphics, lighting and coloring and I can assure you that image was messed around with by someone who didn't know how to do it well. As for conspiracy theories - which is more likely - that someone (inexpertly) messed with the photo - or that there really are blue dog-bear hybrids running around loose unknown to modern science? SteveBaker (talk) 16:43, 15 February 2009 (UTC)

NOW you're really extrapolating, Steve. The only evidence we have is of blue dog-bear hybrids lying on the ground looking dead. Did I miss the photo or other evidence of one running around? You really should stick to the 'facts'. ;-) --Scray (talk) 17:23, 15 February 2009 (UTC)

I realize that specular highlights in computer graphics are usually independent of the color of the object, but as our specular highlight article mentions, in real life it depends on the material—it's true of colored plastics but not colored metals. Whether it's true of rhinariums I don't know, but anyway it makes no difference because that's obviously not the origin of the blue tint here. Surely you've noticed before that black objects in photographs very commonly have a blue tint. Here's a great example from the rhinarium article—would you say that image was photoshopped to make the monkey look blue? I don't think the blue tint in this image was even an issue until you and Cuddlyable3 brought it up. The original poster wasn't asking about a mysterious blue animal, but about a mysterious seeming hybrid of different species. I assume that he interpreted the blue tint the same way I did, as a color-balance problem. It is, as I said, very common and I'm amazed you haven't noticed it before. This is the most similar image I could find in a quick search of the Commons. Does that also have the sudden green-blue transition that you were talking about (look at the forelegs)? Here's another example of a blue nasal highlight (although I admit I'm linking it more because it's friggin' adorable than because I think another example is needed).

Maybe I'm missing something, but your suggestion that a blue tint might mean that "the camera was not registering red and green very well" makes me think you don't understand real-world color at all. In computer graphics white is just an equal combination of red, green and blue, but in real-world imaging it's a considerably more complicated concept. The world isn't sRGB, and our eyes don't see in sRGB. There've been a bunch of good color-vision threads in the Ref Desk—they're worth a(nother) look. Also see color balance, white point, CIE 1931 color space, etc. -- BenRG (talk) 22:18, 15 February 2009 (UTC)

How fair is a coin?

How fair is a physical coin? I mean, what by percentage does it favor heads or tails, when flipped in the standard way -- it must by SOME amount, since there must be more material on one side than the other. Also, how many standard deviations away from the average would this favor be? Thanks! —Preceding unsigned comment added by 82.120.236.246 (talk) 21:57, 14 February 2009 (UTC)

Slightly different, I know, but careful analysis suggests that a coin will land the same way it started about 51 percent of the time. In reality, this probably favours heads. The weighting issue - which would differ based on the coin used - pales in comparison to human jitteriness (which is what actually introduces the randomness), I'm afraid. - Jarry1250 ^{(t, c)} 22:18, 14 February 2009 (UTC)

Is there really a standard way to flip a coin? It can't be completely standardised or the result would be predictable. Cuddlyable3 (talk) 00:10, 15 February 2009 (UTC)

The coin will always favour the side which it was flipped from. This is because the spin is unbiased only if the coin rotates about an axis that is orthogonal to its normal. Otherwise it favours the face starting on top. There are a lot of recent studies that suggest this bias is indeed close to 1%. (Too lazy to find any links). —Preceding unsigned comment added by 99.255.228.5 (talk) 00:44, 15 February 2009 (UTC)

Assuming that each coin flip has the same bias and is independent of all other coin flips, you can correct the bias using some unbiasing procedure. Here's one way to do that:

1. Starting with the head side up, flip the coin once.
2. Starting with the head side up (again), flip the coin a second time.
3. If the two coin flips come out different, take the result of the first coin flip.
4. Otherwise, start over.

This will work so long as the coin flips don't come out the same way 100% of the time. --173.49.17.152 (talk) 17:18, 15 February 2009 (UTC)

You don't even need that many steps - just one:

1. flip twice until you get different results then use the first

Tested like this

C:\>perl -we "$numHeads = 0; $numTails = 0;
   for (1..1000000) {
      while (
         ($first_is_heads = (int rand 10? 1:0)) ==
         (int rand 10? 1:0)
      ){};
   if ($first_is_heads){$numHeads++} else {$numTails++}
   }
   print qq/$numHeads heads - $numTails tails\n/"
500014 heads - 499986 tails

-- good enough for me!

Bias reduces the probability of getting two different results in succession from the ideal 50%. However the bias that affects every individual flip still affects the coin (first) that you choose. A way of reducing the bias is to toss a second coin to choose whether to take the first or second flip of the first coin. Cuddlyable3 (talk) 18:34, 15 February 2009 (UTC)

Actually most coins are heavier on one side than the other.--GreenSpigot (talk) 00:03, 16 February 2009 (UTC)

I'm not so sure I like this "bias preconditioning." I'm not an expert in statistics, but the way I read these prior responses goes something like this: "We have a (semi) non-random set of numbers. We perform a conditioning algorithm. The result is a more-random set of numbers." That would be fine (pseudo-random number?) except it sounds like the algorithm suggested above (only accept the toss if the value changed since last time...) is just a high pass filter. This won't eliminate all bias, it will just eliminate low-frequency biases. Maybe I'm mistaken, maybe the definition of randomness, pseudorandomness, and unpredictability are all worth checking again... Nimur (talk) 16:10, 16 February 2009 (UTC)

Here's an explanation of why the unbiasing procedure doesn't work, not using the concept of frequency. Consider our biased (to fall "heads", say) coin is tossed many times in its lifetime and our first toss is an entry into the stream of results. The bias means we are more likely to enter into a string of recurring heads ...HHHHH... than of tails. Therefore as we repeat tosses, the first time the algorithm finds two different successive results will be at the end of this string i.e. ...HHHT. Encountering TTTTH is less likely. Therefore the first toss selected by the algorithm is still more likely H than T, due to the bias.

Using a second coin as I described reduces but does not eliminate the bias. Tossing an infinite number of times would be the only way to eliminate bias. Cuddlyable3 (talk) 13:21, 18 February 2009 (UTC)

No, using the approach described above ("always flip twice in the same manner, repeat until the results are unequal, then pick the first") will produce heads and tails with exactly 50%. That is a well-known result from probability theory, and it holds for any biased coin as long as the results of the two coin tosses are independent. Note that you have 4 possible results, HH, HT, TH, TT. You throw out HH and TT, leaving you with TH and HT. The probability for the first sequence is P(H)*P(T), the one for the second P(T)*P(H), and since * is commutative, they come out the same. Note also that you do not throw until you detect a change - you always throw pairs. --Stephan Schulz (talk) 15:57, 22 February 2009 (UTC)

Energy vs mass

Does something have energy because it has mass? Or does something have mass because it has energy? Or do the two exist because of some higher attribute?128.163.224.222 (talk) 23:02, 14 February 2009 (UTC)

Both, the two are really just different manifestations of the same thing. Einstein's famous equation, E=mc², tells us how they are related. The c² part is really just there to convert the units - from kilograms to joules or whatever (just like you have to multiply by 2.54 to convert inches to centimetres, you have to multiply by 3x10⁸ to convert kilograms to joules). Essentially, energy and mass are equal. We often talk of rest mass, which is the mass something has when it doesn't have any other energy (what gives things their rest mass is something of an open question, see Higgs mechanism if you want the technical details of the most popular theory). When you move an object you give it kinetic energy, that results in it having a greater mass (we call it relativistic mass). It's that greater mass that makes it impossible to accelerate something to the speed of light - as it gets faster and faster and gets heavier and heavier and takes more and more energy to accelerate it, it would take an infinite amount of energy to get it all the way to the speed of light. Does that help at all? --Tango (talk) 23:22, 14 February 2009 (UTC)

In ordinary experience mass and energy are independent properties that co-exist. Only extreme cases such as nuclear fusion or fission, such as in the sun or A- and H-bombs, demonstrate that one can convert into the other. Whether there is some higher attribute than these in the universe sounds like a religous question. Cuddlyable3 (talk) 00:06, 15 February 2009 (UTC)

It's a perfectly reasonable scientific question - if two things are related, it's sensible to ask if perhaps they have a common cause. --Tango (talk) 00:16, 15 February 2009 (UTC)

Electric fields and magnetic fields can be converted into one another—because they are basic components of a single electromagnetic force. Asking the underlying connections between related quantities is one of the fundamental physics questions, nothing to do with religion. --98.217.14.211 (talk) 04:02, 15 February 2009 (UTC)

The illustration I like is that a hot cup of coffee is slightly heavier than it is when it has cooled off. --Chetvorno^TALK 07:57, 15 February 2009 (UTC)

Just because we can write down an equation which relates two quantities by nothing but a constant of nature does not mean that these two quantities are the same. In fact, energy and mass are two different things, in relativistic as in Newtonian physics. That's relatively easy to see mathematically (energy is the time-component of a particle's four-momentum, mass is the four-momentum's invariant length, hence the full connection is $E^{2}-p^{2}=m^{2}$, where I have set c=1), and somewhat harder to describe in words. I like to put it as follows: Energy (along with its companion, momentum p) describes how a particle is moving. This should make it obvious that the energy of a particle depends on the reference frame in which it is measured, as is the case for kinetic energy in Newtonian mechanics. The mass of a particle puts constraints on the motion that is possible for that particle (because the relation $E^{2}-p^{2}=m^{2}$ has to be fulfilled). Famously, particles with zero mass always travel at the speed of light, particles with mass have to travel at less than the speed of light. $E=mc^{2}$ is a special case of the relation quoted above, and is valid in the particle's rest frame. It says that even when a particle is at rest, we have to attribute an energy (numerically equal to its mass, multiplied by c², although that's just a matter of the units we use) to it, something that is not the case in Newtonian mechanics. --Wrongfilter (talk) 12:42, 15 February 2009 (UTC)

That's rest mass, of course. The now unfashionable relativistic mass is just the same thing as energy. Algebraist 13:58, 15 February 2009 (UTC)

Indeed. It's unfashionable because it isn't actually very useful when doing calculations, and whatever. It is, however, quite a good way of thinking about it when you are trying to get your head around why the speed of light takes infinite energy, and related concepts - that's why I answered the OP's question in terms of it. --Tango (talk) 15:01, 15 February 2009 (UTC)

Above, it was mentioned that "Only extreme cases such as nuclear fusion or fission, such as in the sun or A- and H-bombs, demonstrate that one can convert into the other". This is a common fallacy! A 25 keV cathode ray such as the one in your old cathode ray tube television could easily impart enough potential energy to introduce a mass artifact on the electrons as it hurtles through the unit. This can and does introduce a noticeable shift in the trajectory of the beam, which must be compensated for by the controlling electronics, else the raster scan doesn't work properly. (Reference: Cathode Ray Tubes, R. Casanova Alig, Sarnoff Corporation, 1999). "The electrons leave the gun at speeds of 5% or more of the speed of light. This speed is high enough for the theory of relativity to change the electron path perceptibly from that expected from Newtonian physics. The CRT is unusual, perhaps unique, among household objects, in that relativistic effects are significant." Perhaps mass-energy equivalence is not such an extreme case after all! Nimur (talk) 16:18, 16 February 2009 (UTC)

Runaway propeller

I am listening to A Case for Dr Morelle on the BBC iPlayer, and an aeroplane in the story suffers from a "runaway propeller". What might this be? DuncanHill (talk) 23:52, 14 February 2009 (UTC)

If the governor associated with a constant-speed propeller fails, the propeller blades may feather to an extremely fine pitch. This will sharply reduce the load on the engine, and – unless corrective action is taken immediately – the engine may redline. Damage can occur to the overspeed prop itself, to the engine, or both. (A rough analogy from the driving world — imagine driving at highway speed and suddenly shifting down into first gear.) TenOfAllTrades(talk) 04:05, 15 February 2009 (UTC)

If the engine speed is constant and the pitch is automatically controlled, what is left for the pilot to control? How does he adjust the thrust? —Bromskloss (talk) 12:26, 15 February 2009 (UTC)

The name 'constant-speed prop' is a tad misleading. It shouldn't be read to mean that the prop maintains a constant speed at all times during the flight; as you've quite correctly surmised, that would leave no obvious way to control thrust. Instead, the pilot has a second control in the cockpit (usually adjacent to the throttle) which allows for selection of the target engine speed (RPM). On takeoff and climb, the pilot will choose a high speed, corresponding to finer prop pitch and greater power. During level flight, the pilot will move to a lower speed, corresponding to greater prop pitch, lower engine speed, and better fuel economy.

Here are a couple of links that go into a bit more detail: [7], [8]. TenOfAllTrades(talk) 14:16, 15 February 2009 (UTC)

Aha! Thank you. —Bromskloss (talk) 10:58, 16 February 2009 (UTC)

• Excellent, many thanks! DuncanHill (talk) 15:46, 15 February 2009 (UTC)

Can we create giant insects like those that lived during the Carboniferous period?

During the Carboniferous period, insects could grow much larger than today due to the high oxygen levels. So, why can't we breed insects under high oxygen conditions and select for size, or use genetic manipulation techniques to create large insects? Count Iblis (talk) 23:57, 14 February 2009 (UTC)

We probably could if we really wanted to. I'm not sure selective breeding would get us anywhere near those sizes in a reasonable amount of time, but genetic engineering might be able to. --Tango (talk) 00:04, 15 February 2009 (UTC)

The American cockroach can grow to amazing size. (Not quite big enough to saddle, despite the common saying.) Which leads to the question what you'd do with your giant bug and what would it feed on? There may be some use in the entertainment industry (Godzilla vs Ibis bug). Our next problem, though, is going to feed the steadily growing human population, not entertaining them. If your bugs were edible, could be fed on something that would not have a negative net food value it might be worth the resources expended to create and maintain it. All that would be left to do would be to train humans not to get the creeps when they find out what's in that hot dog. But then there are cultures who eat bugs.76.97.245.5 (talk) 02:24, 15 February 2009 (UTC)

There is a perfectly extant and very large terrestrial arthropod, the Coconut crab. It's not an insect, and its respiratory system is quite different from that of the modern insects; but it is still an arthropod (so same basic body arrangement, exoskeleton, open circulatory system, etc...). Does it fit your bill? Or are you rather asking about "breeding back" Meganeura and such? --Dr Dima (talk) 03:54, 15 February 2009 (UTC)

Probably a major reason those insects were able to grow bigger was because there was more oxygen in the air. Which is good for the rest if us as you'll have to keep them in a special enclosure. I've seen the effects when such creatures are released.:) Dmcq (talk) 12:25, 15 February 2009 (UTC)

Yes, I think that is understood to be the primary reason they were bigger. The OP said as much. --Tango (talk) 15:03, 15 February 2009 (UTC)

We still have a few moster flying insects around: Attacus atlas the Atlas Moth for instance, and Ornithoptera alexandrae the Queen Alexandra's Birdwing butterfly. Although neither of them comes anywhere near Meganeura's 30 inch wingspan. SpinningSpark 16:13, 15 February 2009 (UTC)