Wikipedia:Reference desk/Archives/Science/2008 September 3

= September 3 =

brown sugar
What is the chemical name of the drug commonly known as "brown sugar" —Preceding unsigned comment added by Dbeein (talk • contribs) 01:05, 3 September 2008 (UTC)
 * Brown sugar (disambiguation) says: A "street name" for heroin. See also a Google search on "brown sugar" heroin. PrimeHunter (talk) 01:24, 3 September 2008 (UTC)

Clarity of Glycerin soap
Since glycerin soap is simply homemade soap (without glycerin removed), why is it clear and not opaque? Do this have something to do with the alignment or molecular arrangement of the soap molecule with glycerin? Sjschen (talk) 01:13, 3 September 2008 (UTC)


 * just gossip here, but I thought the clear soaps were first cleaned using ethanol to make them look nice. Polypipe Wrangler (talk) 00:36, 4 September 2008 (UTC)


 * As I understood it was so that if you dropped it in water, it wouldn't end up being a hazard for you tripping on it because you could clearly see it. 66.216.163.92 (talk) 01:48, 5 September 2008 (UTC)

Separating a test tube mixture
I was given this problem a few days ago, and I was wondering if someone had any ideas on how to do this easily. This is the original question:
 * "You are given a test tube that contains the following mixture of substances
 * sand
 * salt
 * sawdust
 * iron filings
 * benzoic acid
 * Salt and benzoic acid dissolve in water, while the sand, iron, and sawdust (which is
 * less dense than water) do not. However, benzoic acid does not dissolve until the
 * temperature of the water is above 50 degrees Celsius. Use this information to devise
 * a method to separate the mixture so you could return to me 5 vials each containing
 * one of the five pure substances in the mixture."

My first idea was to use a magnet to separate the iron filings from the mixture. Then you could add room temperature water to the mixture, and strain the contents so that you would be left with salt water that could be boiled and thus separating the salt from the water. But then I can't figure out a way to separate the sand, sawdust, and iron filings from the mixture. Any help would be greatly appreciated! Thanks in advance! - jesusfreak210 (talk) 03:32, 3 September 2008 (UTC)
 * You're right up until the final statement; you've already separated out iron filings. To separate sand and sawdust, take advantage of their differences in density. anonymous6494 04:05, 3 September 2008 (UTC)
 * Ok thanks, thats what I was thinking. And the iron filings thing was just a typo... sorry.  Thanks again!  - jesusfreak210 (talk) 04:14, 3 September 2008 (UTC)
 * There was an old puzzle of separating salt and pepper; you combed your hair with a plastic comb and the pepper is attracted by static electricity. I wonder if sawdust might be attracted in the same way.--TrogWoolley (talk) 22:10, 3 September 2008 (UTC)
 * So you add hot water. Then:
 * Sawdust floats - none of the others do - so you can skim them off.
 * Iron filings are magnetic - so you can stick a magnet into the test tube and pull them out.
 * Sand sinks to the bottom - and isn't magnetic - so you can pour off the rest of the liquid and recover the sand.
 * Benzoic acid and salt both dissolve.
 * Benzoic acid is only soluable in hot water - so cool the mixture and the benzoic acid comes out of solution and can be filtered out with filterpaper.
 * The Salt can then be recovered by boiling the water until there is none left.
 * Of course, in reality, you'll have somewhat salty sawdust, iron filings and sand - but you can repeat the process as many times as necessary to progressively dilute the salt to whatever degree of purity you need. SteveBaker (talk) 22:21, 3 September 2008 (UTC)
 * Steve, I understand your answer was well intentioned, but please try to avoid the urge to outright do students' homework for them. --68.166.144.211 (talk) 15:39, 4 September 2008 (UTC)


 * Just a piece of practical advice: wrap the magnet in paper or something for if the iron filings stick directly to an iron magnet it's very difficult to remove it. &#x2013; b_jonas 22:32, 6 September 2008 (UTC)

Blindness disease
Blindness (novel) and the related Blindness (film) present a plot premised on an epidemic of blindness triggered by some unspecified infectious agent.

I realize that in the real world there are no diseases that causes blindness to spread like the flu. However, I am wondering if there are any communicable diseases at all where blindness is a major symptom. Some form of bacterial agent that affects the eyes perhaps? Thanks indulging my idle curiousity. Dragons flight (talk) 05:02, 3 September 2008 (UTC)


 * Syphilis and onchocerciasis come immediately to mind. In susceptible hosts (e.g. AIDS but also in others), there are many, including cytomegalovirus, varicella zoster virus, herpes simplex virus, and Pneumocystis jirovecii.  It's actually a pretty long list. Scray (talk) 05:06, 3 September 2008 (UTC)
 * Probably should clarify that only tertiary syphillis and neurosyphillis present with visual problems. You would not experience this symptom with primary syphillis, by far the most common in industrialised nations, since we almost always catch syphillis in it's primary stages before it progresses to secondary, tertiary or neurosyphillis. Tertiary syphillis and neurosyphillis are more common in immunocompromised persons, such as those suffering from AIDS. —Cyclonenim (talk · contribs · email) 10:34, 3 September 2008 (UTC)
 * Fair enough, but I'm in a U.S. city and I've seen 2 people with sight-impairing ocular syphilis just in the past 6 months. One of them did have HIV (not AIDS), but the other did not and the point is that it's still happening. Scray (talk) 11:21, 3 September 2008 (UTC)
 * What about viral conjunctivitis? It spreads fast and when people who haven't been exposed to it to get it they often cannot open their eyes with swelling. In West Africa where I used to live it was called "Apollo's sickness" because there was a huge rapid epidemic of it after the return of the moon shuttle. Not permanent but very fast like flu and up to a week of practically no sight.--BozMo talk 15:21, 3 September 2008 (UTC)


 * At the bottom of the onchocerciasis article, there's a template which can be expanded to reveal all kinds of eye diseases. Notably Trachoma, a bacterial infection which spreads between people and has claimed the sight of 8 million people worldwide. EverGreg (talk) 18:56, 3 September 2008 (UTC)

Solvents of common pharmaceuticals
Removed by original questioner who was fed up with the obstructionist antics, assumptions of bad faith, trolling and general lack of good will of certain editors who really should know better. DuncanHill (talk) 22:58, 3 September 2008 (UTC)


 * (edit conflict) Yeah, we are now officially less helpful than Yahoo! Answers. (HTH, the technique given involves solvents the OOP said he tried, but maybe the technique is at issue.)  -- Coneslayer (talk) 22:58, 3 September 2008 (UTC)

Long-term monogamy in mammals
Which mammals (one example I know is Peromyscus polionotus) show long-term monogamy?  Otolemur crassicaudatus  (talk) 11:27, 3 September 2008 (UTC)
 * Swans, parrots, red wolves and humans are a few well known ones. I can't find a full list, but true monogamy is very rare, at least according to this. Jessica   Thunderbolt   12:00, 3 September 2008 (UTC)
 * Swans and parrots are mammals now? DuncanHill (talk) 12:19, 3 September 2008 (UTC)
 * I need my head examined! Thanks for correcting me. Jessica   Thunderbolt   12:28, 3 September 2008 (UTC)

Physics
Hi, why is physics different than other natural science (studies)? Thank you. —Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 15:33, 3 September 2008 (UTC)


 * Read physics and natural science and you'll find many answers to your question. -- k a i n a w &trade; 16:27, 3 September 2008 (UTC)


 * I'm not sure exactly what your question is about, but physics, as a natural science, has the distinction of dealing with the most fundamental of abstractions. Other scientific disciplines deal with more complex systems at various higher levels of abstraction. --72.94.50.58 (talk) 00:45, 4 September 2008 (UTC)


 * What "other natural science"? Physics is THE natural science.  The rest are either just special cases (like chemistry) that has grown too large that they have to be broken out but they too are physics, or just stuff people are trying to sell as natural science (but is really applied science, humanties, or, worse, pseudoscience).  &#x2013; b_jonas 22:27, 6 September 2008 (UTC)

Wikipedia:Unidentified flowers
Please identify the flowers at Unidentified flowers and delete the page once completed. Thanks. Suntag (talk) 16:53, 3 September 2008 (UTC)


 * No, thanks. — OtherDave (talk) 17:39, 3 September 2008 (UTC)
 * Maybe you've mistaken us for the Bounty board? Jessica   Thunderbolt   17:45, 3 September 2008 (UTC)
 * How much do you want? 93.132.165.7 (talk) 18:31, 4 September 2008 (UTC)


 * Don't mind the other replies&mdash;I personally think this is a perfectly legitimate request for the Ref Desk. We wouldn't be jabbing at Suntag if he had posted the pics on this page and asked us to ID them, would we?  If anyone knows of good resources for the identification of flowers (or other plants, for that matter) post 'em here; I'd find it useful information.
 * For reference, there are half a dozen images of flowers, snapped in Belize. Good hunting! TenOfAllTrades(talk) 19:41, 3 September 2008 (UTC)
 * I don't. Would you give such a command to a real-life reference desk librarian?  --Sean 14:50, 4 September 2008 (UTC)
 * "A command"? Which command is that? Axl (talk) 19:01, 4 September 2008 (UTC)
 * Would you ask a "real-life reference desk librarian" about Higgs bosons, evolution or other such things? —Cyclonenim (talk · contribs · email) 20:43, 4 September 2008 (UTC)
 * That's not a command: that's a question. Axl (talk) 21:13, 4 September 2008 (UTC)
 * Okay. Would you ask demand that a librarian should define the word entropy? The point stands, we are not librarians. We are a group of people interested in different subjects. —Cyclonenim (talk · contribs · email) 23:26, 4 September 2008 (UTC)
 * What is the problem? An editor asked politely for people to identify some flowers. He said please and thank you. He didn't clutter up this page with a large gallery, but thoughtfully made a separate page for them. DuncanHill (talk) 23:31, 4 September 2008 (UTC)

""Would you ask demand that a librarian should define the word entropy?""

- Cyclonenim


 * Would I? I would neither ask nor demand that (as you well know). I already have an idea what entropy is (but would need to look up a formal definition). I know how to find out answers to these "definition" questions without asking for help. However not everyone has these skills, notably newbies (to Wikipedia) and younger people. It is ironic that this area is called "Reference desk". The introduction states "The Wikipedia reference desk works like a library reference desk." The librarians' work at reference desks is mainly to find books and articles, to induct new members, and answer questions about borrowing items from the library. Wikipedia's reference desk isn't a desk. It is viewed by dozens of users who answer questions, often highly specialist (e.g. Higgs bosons). Axl (talk) 07:39, 5 September 2008 (UTC)


 * I SEVERELY ORDER YOU ALL TO REMOVE INSTANTLY AND WITHOUT THINKING ANY QUESTIONS THAT COULD BY, IN EVEN THE MOST HYPOTHETICAL ASPECT, BE CONSIDERED AS SEEKING FOR MEDICAL, LEGAL OR PROFESSIONAL ADVICE. I FURTHER COMMAND THAT YOU CHECK ANY ANSWERS OF YOURS AS WELL AS OF ANY OTHER PEOPLE AGAINST ALL LAWS OF EVERY EXISTING GOVERNMENT. Hope that helps. And, yea, remove that, too. 93.132.165.7 (talk) 18:31, 4 September 2008 (UTC)

Monogamy and Evolution
From what I understand (which is admittedly very little) about the evolution of our species, monogamy/pair bonding seems to be viewed as a helpful mechanism for protecting the weaker infant and mother and ensuring the replication of our genes. If this is true, I would think that the seperation of parents would be highly unusual, but this is not the case, especially in Western cultures. So why are parents so ready and able to deviate from the course seemingly plotted by our genes? Thanks in advance! 90.192.223.228 (talk) 19:29, 3 September 2008 (UTC)


 * The basic answer is that monogamy is evolutionarily advantageous to a parent only if it increases their inclusive fitness, which generally equates to the expected number of offspring successfully raised. (The "generally" is there because this simple definition does not take into account the fact that healthier/richer/etc. offspring may themselves have a higher chance of successfully passing on their genes.)  Also, monogamy is typically only practical if it is in the interests of both parents — for most species, there's little one parent can do if the other parent decides to just up and leave.  Typically, the parent more inclined to leave is the male, since their initial investment in the offspring in lower and the potential gain from seeking more mates higher; thus, monogamy is usually only stable if the improvement in the survival odds of offspring with both parents around to raise them is significant enough to compensate for the reduction in further reproductive opportunities the male must give up to take care of his earlier offspring.  This is not quite true, since, if there is some way (e.g. elaborate and costly courtship rituals) for the female to try to predict the "fidelity" of males, they may prefer those males that are more likely to stay around and thereby stabilize monogamy even in the presence of incentives for males to cheat, but it's still a pretty good first approximation.


 * Even then, the choice between staying monogamous or looking for other mates is in reality not always an either-or decision, and there are strong evolutionary incentives for both parents to try to get "something for nothing" if they can get away with it. For males, this may mean trying to mate with other females even while only looking after one's "primary" family: though the gain may be uncertain, this costs little for the male.  For females, it may involve trying to mate with a seemingly fitter, but already paired, male (and thereby hopefully gain better genes for one's offspring) while trying to convince another male to raise said offspring as his own.  The end result of all this is a complicated game of cheating and counter-cheating strategies, for which strict monogamy and polygamy are simply two extremes along a wide and complex spectrum.


 * Incidentally, if anyone thinks I've been basing the above paragraphs on observations of human behavior, that isn't really the case: all this evolutionary complexity is much more clearly observable for example among various nominally monogamous bird species. Indeed, the fact that such simplistic reasoning, based on studies of species with a simple social structure, coincides so well with observed behavior even among such a complex social species as humans is quite surprising.  Indeed, it's true that human behavior is in many ways yet more diverse, in large part thanks to our capacity for cultural evolution and for forming complex societies with ties extending beyond the pair level.  Nonetheless, that fact that, even among species with simpler, more deterministic social behavior, evolution generally does not favor strict monogamy should at least suggest the unlikelihood of such inescapable genetic imperatives in a species as complex as ours.  —Ilmari Karonen (talk) 21:04, 3 September 2008 (UTC)

Insect Identification
I recently found this insect and haven't the slightest idea what it is. It's about two inches long, holds its wings like a damselfly when at rest, and was found in Colorado. Photos one and two of it. Thanks in advance. PetrusCuniculus (talk) 20:07, 3 September 2008 (UTC)


 * It looks like some species of Dragonfly...but I'm no expert. SteveBaker (talk) 03:39, 4 September 2008 (UTC)


 * Looks like an antlion. Matt Deres (talk) 17:41, 4 September 2008 (UTC)


 * It's definitely an antlion. Thank you! —Preceding unsigned comment added by PetrusCuniculus (talk • contribs) 19:17, 4 September 2008 (UTC)

Wifi - any dangers?
Hello wikipedia,

I have no idea if i'm opening up a can of worms here but, here goes. Is there a health risk associated with having your wireless router in your bedroom? I can't find a discussion of the health risks on wikipedia but surely people like the Daily Mail must have ran stories?

Thanks, 82.22.4.63 (talk) 19:47, 3 September 2008 (UTC)
 * From the discussions I was able to find from a google search, not likely. Maybe if you tape the router to your head and walk around with it 24/7, but besides that? No. Paragon  12321  19:54, 3 September 2008 (UTC)


 * (ec) Depending on the exact position of the router in your bedroom, your significant other may complain about it and demand that you put it somewhere else. Whether this constitutes a health risk is debatable (and may depend on the circumstances), but I do seem to recall some studies suggesting that people with healthy sex lives tend to live longer on average.


 * Also, if you're thinking of installing the router in your bedroom in order to use a laptop in bed, it's likely that disturbances to your circadian rhythm due to excessive late-night computer use, not to mention the possible ergonomic problems from bad posture etc., may indeed have both acute and chronic health effects.


 * Finally, please remember that the Reference Desk may not offer any actual medical advice. The standard Wikipedia medical disclaimer also applies.  —Ilmari Karonen (talk) 20:01, 3 September 2008 (UTC)


 * See Wireless electronic devices and health. Jessica   Thunderbolt   20:05, 3 September 2008 (UTC)
 * Your significant other may hit you for spending too much time on Wikipedia in the bedroom. Clarityfiend (talk) 02:04, 4 September 2008 (UTC)


 * It seems very unlikely that WiFi would be a problem. Compare to a cellphone:  A cellphone has to push it's signal a mile or more - often through walls - and you hold the antenna less than an inch from your body.  WiFi only goes a few hundred feet, it doesn't work well through walls - and you rarely get within a few feet of it.  Because the amount of radio energy you might absorb decreases as the square of the range - merely being 100 times further from your WiFi antenna than you are from your cellphone antenna means that the power you'll absorb is 10,000 times less.  Since MANY studies of cellphones have failed to produce a conclusive link between cellphone use and general health - we can assume that the risk from WiFi is vastly less than the amount needed to produce any kind of health issue. SteveBaker (talk) 03:24, 4 September 2008 (UTC)


 * WiFi Laptops. Presumably it would be a sensible precaution for people of childbearing age and younger NOT to sit or recline for long periods with a laptop on their lap with the WiFi switched on and its antenna close to reproductive organs. I now use mine at a table etc, or with the WiFi switched off. Perhaps a precautionary health warning would be in order, pending further research. GilesW (talk) 16:55, 10 September 2008 (UTC)

Looking for references about cats
Hello, I just read a couple of facts about cats and I would like to check if they are really true. I would be very pleased if you could confirm or refute these facts, and provide weblinks where I can read more about it.

These facts are:


 * a) old age in cats is not gradual like in humans; it appears suddenly, and lasts approx. 1 year before the animal dies.
 * b) domestic cats are not very wary when crossing roads. they seldom look around when they are about to cross, and therefore get run over relatively often.

Thanks to anyone who can help. Leptictidium (mt) 20:39, 3 September 2008 (UTC)


 * I can testify from experience that my cat is very cautious when crossing roads — they are, after all, open areas often populated by big noisy things. If there's any sign of traffic — whether vehicular or pedestrian — on the road, he'll prefer to wait in a suitable hiding place until the way is clear, and when he does decides it's safe to cross, he'll do it quickly.  However, I doubt he has a particularly good understanding of how cars actually behave, and thus sometimes his decisions on when it would be best to stay and when to cross may seems, if not unwise, then at least quite surprising from a human viewpoint.


 * Indeed, I suspect a particular risk is that, for cats, avoiding danger normally means avoiding being seen. Thus, a cat crossing a road will stay hidden in the bushes until he thinks the way is clear, and then dash across.  Should the cat misjudge, this gives a human driver very little chance to react and avoid a collision.  —Ilmari Karonen (talk) 21:13, 3 September 2008 (UTC)


 * It varies with the cat, in the second instance. Some cats are very good about roads. Some are not. I've no idea what accounts for the difference. --98.217.8.46 (talk) 21:44, 3 September 2008 (UTC)


 * BTW I've read Elizabeth Marshall Thomas say that her dog used to listen for cars instead of looking for them; it had no problem crossing the street whenever it was safe. --Kjoonlee 05:23, 5 September 2008 (UTC)


 * Statistically, the lifespan of a cat kept indoors is 12 to 14 years, while that of a cat allowed outdoors is about four years., .  A goodly amount of that difference is due to automobiles. You can read more by Googling for "cat lifespan indoors outdoors".  - Nunh-huh 05:33, 5 September 2008 (UTC)

Cystic fibrosis
The article on Cystic fibrosis says: "The CFTR gene is found at the q31.2 locus of chromosome 7, is 230,000 base pairs long, and creates a protein that is 1,480 amino acids long. The most common mutation, ΔF508 is a deletion (Δ) of three nucleotides that results in a loss of the amino acid phenylalanine (F) at the 508th (508) position on the protein. This mutation accounts for two-thirds of CF cases worldwide and 90 percent of cases in the United States; however, there are over 1,400 other mutations that can produce CF.[32]"

My question: do these 1,400 mutations also occur on alleles in the CFTR gene, or do these mutations occur on other genes? If the latter is true, is each mutation also a three-nucleotide deletion? Thanks, Nishkid64 (Make articles, not wikidrama) 21:33, 3 September 2008 (UTC)


 * All known CF-causing mutations, if I'm not mistaken, are mutations of CFTR. The mutations vary widely in their change and effect, many are insertions of a stop codon, but there's plenty of missense mutations and frame-shift mutations, too. &mdash; Scientizzle 22:26, 3 September 2008 (UTC)
 * This database shows the variety, also including promoter and splicing mutations. &mdash; Scientizzle 22:29, 3 September 2008 (UTC)


 * Another source for references to papers on CF inheritance is the Online Mendelian Inheritance in Man page on cystic fibrosis or on CFTR proper. - Nunh-huh 06:35, 5 September 2008 (UTC)

Invisibility Cloak
This article says that a major flaw in invisibility cloaks is that if you were inside one, the world would be invisible to you. Since objects behind an invisibility cloak are perceived as transparent (hence, invisible), what would it look like if the entire world and universe were transparent? This does not make sense to me. I'm sure you would see something, even if it is just your own reflection. Any ideas?--ChokinBako (talk) 23:05, 3 September 2008 (UTC)
 * If I understand the article you've linked correctly, from inside you will see the cloak as a black barrier. Algebraist 23:16, 3 September 2008 (UTC)
 * More accurately, you wouldn't see anything, since it would be dark inside the cloak. This is true by definition, since an invisibility cloak cannot let any light in from the outside without being at least partially visible.  I'm not sure offhand what would happen if you had your own light source (e.g. a lamp) inside the cloak: presumably either the light would leak out (thus betraying your location, but still not helping you to see), or, more likely, it would be reflected back from the cloak (possibly in funny ways, since we're talking about some seriously weird optics here).  —Ilmari Karonen (talk) 23:31, 3 September 2008 (UTC)
 * Actually, you could of course make the cloak look like any ordinary (opaque) material from the inside, by the simple expediency of lining the inside of the cloak with said material. —Ilmari Karonen (talk) 23:34, 3 September 2008 (UTC)
 * You could have a couple of tiny pin pricks for eye holes. Since they could be really close to your eyes, you could see quite well and they would be very difficult for anyone outside to notice. --Tango (talk) 23:39, 3 September 2008 (UTC)


 * An interesting question would be what happens to light that would've passed through the eyeholes. Obviously, light that hits the eyeholes directly simply goes through the hole and gets absorbed by your eyes, so the holes should appear (mostly) black from the front.  But what about the light that would've come out of the cloak through the eyeholes?  In general (handwaving away all those pesky details about actual construction of physical invisibility cloaks) I see two possibilities here: it gets either absorbed or retroreflected.  The former simply makes the eyeholes appear black from the other side as well.  The latter, however, might be more interesting if you were, say, thinking of writing a science fiction story with such devices in it, since it would imply, among other things, that if you were wearing an invisibility cloak in the dark and someone shone a light at the back of your head, your eyeholes would act as retroreflectors.  Oopsie...  —Ilmari Karonen (talk) 00:56, 4 September 2008 (UTC)
 * Presumably it would be absorbed, I can't see any reason for it to be reflected, nothing has happened to the other side of the cloak. --Tango (talk) 02:42, 4 September 2008 (UTC)


 * What silliness. Obviously any reasonable invisibility cloak will magically duplicate each photon that reaches it.  That way one photon can be passed to the inside to allow the wearer to see and another can be sent out the back so as to make the wearer appear invisible.  Dragons flight (talk) 00:37, 4 September 2008 (UTC)


 * Yes - and it is very hard to duplicate photons without magic. There is no way that they could have light sensing material in the cloak that could feed video to an interior screen.  Cameras and monitors?  Truly magic. --  k a i n a w &trade; 00:51, 4 September 2008 (UTC)
 * Without magic it is very hard to remain invisible if your cloak is made of "light sensing material". APL (talk) 01:13, 4 September 2008 (UTC)


 * Current invisibility cloak research uses fiberoptics to bend light around an object and send the light on its way on the opposite side of the object. If only one out of every million or so photons was detected, it would not destroy the "invisibility" of the cloak. --  k a i n a w &trade; 01:16, 4 September 2008 (UTC)


 * I think we're all missing something. In "real" invisibility research, you aren't expected to be invisible when viewed from every possible direction.  The main requirement is for camoflage - and in that case, you probably know roughly where the enemy is coming from - so light coming from behind you has to be absorbed and regenerated at your front - or routed around you or something - but light coming from in front of you could pass through the "cloak" and allow you to see normally.


 * It would be really tough to make a "cloak" that would make you invisible from every direction because whatever devices are routing light from behind to your front would be blocking some of the light coming from the front toward your rear. When you also consider that light coming from (say) 20 degrees to the right - also has to be detected by sensors that overlay the emitters for front/back transmission - and you rapidly realise that true 360 degree invisibility is very hard to imagine indeed. SteveBaker (talk) 03:33, 4 September 2008 (UTC)
 * Actually, real invisibility research (no quotes required) does involve being invisible from all directions, as I understand it. See . --Tango (talk) 06:07, 4 September 2008 (UTC)

In a futuristic sci-fi cop story some years ago, cops on a stake-out routinely sat in a car in which each window was a video display of what a camera diametrically opposite saw, so that the cops sitting in the car were practically invisible. But the same camera pointing East could display on the inside of the East window an image for the cops inside to watch. This would clearly yield some parallax artifacts if someone was walking by the car, but might be less obvious than being able to see 2 guys sitting in a car eating donuts and drinking coffee all day. An "invisibility cloak" does not have to be perfect to be better than just standing there in broad daylight. Edison (talk) 04:39, 4 September 2008 (UTC)
 * The bigger problem is that that only works if you look at the window from directly in front of it. If you look from the side, you'll see something completely wrong. Far better just to have tinted windows. --Tango (talk) 04:52, 4 September 2008 (UTC)


 * Not so new apparently  —Preceding unsigned comment added by TrapdoorTrevor (talk • contribs) 13:47, 4 September 2008 (UTC)