Wikipedia:Reference desk/Archives/Science/2011 March 28

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March 28

Melting point of graphite: Lower in Japan?

This article says that graphite plugs in the Kukushima Daichi reactors "start to melt" at 350 C. That seems implausible, since graphite is used in various applications in a solid state at much higher temperatures, as in arc lights. Could graphite really melt at 350 Celsius? The Graphite article does not appear to state a melting temperature. Edison (talk) 00:05, 28 March 2011 (UTC)

That article actually says 350°F, which is even lower (177°C). That does seem to be a mistake. According to this article: [1], graphite melts (technically it sublimes, or turns to vapor) at around 3652-3697°C. This assumes normal atmospheric pressure though, could that be the difference ? StuRat (talk) 00:29, 28 March 2011 (UTC)

My guess is the "graphite plugs" are not made of pure graphite, but have something else in them which is what does the melting. Our carbon article says that carbon in normal atmospheric pressures doesn't even HAVE a melting point as it sublimates at about 3900 K. Even given that, 177 deg C still sounds wrong. Vespine (talk) 00:36, 28 March 2011 (UTC)

Another thought, could the plugs come loose, due to contraction and/or expansion ? They wouldn't need gravity to pull them out, if water can then get underneath them and turn to steam. This certainly isn't "melting", but some reporter could possible get confused and call it that. StuRat (talk) 01:24, 28 March 2011 (UTC)

Yep. my book (columbia enc.) gives carbon (12 that is)melt.pt 3550 C. gas off 4827 C. definitely sounds like journalistic error or typo.Phalcor (talk) 04:01, 28 March 2011 (UTC)

Carbon-graphite impregnated epoxy resin sealing rings are widely used in industry and the epoxy breaks down around 350 deg... and a few degrees less if it is wet heat. They don't melt, they become soft and crumbly and start to smell very unpleasant. Fairwinds (oh the irony) have posted a diagram of the projected radioactive leak path.--Aspro (talk) 10:11, 28 March 2011 (UTC)

Is that 350° F or 350° C ? In either case, it seems rather reckless to use a material so poorly suited to withstand the maximum temperature. StuRat (talk) 20:57, 28 March 2011 (UTC)

350F. In a boiling-water reactor, it is theoretically impossible for the temperature to get above 212F, so a hundred-degree safety margin would be plenty. Unfortunately, theory and practice are busy disagreeing right now... --Carnildo (talk) 22:49, 29 March 2011 (UTC)

Only at atmospheric pressure. At around 3.5 atmospheres, the boiling temp goes up to 350° F (do reactors explode before they reach that pressure ?). Not allowing for the possibility of water leaking out and/or becoming pressurized in the reactor core seems rather negligent. Their "theory" appears to be that nothing will ever go wrong. StuRat (talk) 23:03, 29 March 2011 (UTC)

car (celebrities registration of)

can i register a car under a fake name like celebrities do? — Preceding unsigned comment added by Wdk789 (talk • contribs) 05:43, 28 March 2011 (UTC)

What country are you in? Anyway, do celebrities do this, or register the car under their agent's name? I've made the title more descriptive. CS Miller (talk) 06:11, 28 March 2011 (UTC)

us — Preceding unsigned comment added by Wdk789 (talk • contribs) 07:15, 28 March 2011 (UTC)

If you're in the U.S. no. you need identification proof/documentation.190.148.135.138 (talk) 07:25, 28 March 2011 (UTC) reformatted last response. Richard Avery (talk) 08:01, 28 March 2011 (UTC)

As of a decade ago (last time I had to care), it was possible in California for someone other than the legal owner of a car to submit the registration paperwork provided that the legal owner signed the forms and all other necessary documentation was provided. You have to show up in person to get a driver's license, but someone else could submit registration paperwork. Not sure if that is still the case, or whether different rules apply in different states. Dragons flight (talk) 08:51, 28 March 2011 (UTC)

In the UK a vehicle is registered at the DVLA in the name of its "Registered Keeper", who need not be the owner, but is responsible for paying the Vehicle Excise Duty on it, ensuring it's ensured, etc. AndrewWTaylor (talk) 19:45, 28 March 2011 (UTC)

Do you really need the driver's license? What if you don't drive your own car yourself? Can a car be registered at the name of company? 212.169.184.189 (talk) 02:18, 29 March 2011 (UTC)

Pressurized storage of liquids

Suppose we have a 1 litre container of water (or any other drinkable liquid). Is it theoretically possible to pressurize the container to, say, 300 ml capacity so that this smaller container would still be able to contain 1 litre of water (something like black hole)? Specifically, is there any material capable to withstand the associated water pressure while being flexible enough to allow the needed external pressure?--89.76.224.253 (talk) 10:05, 28 March 2011 (UTC)

It's doubtful. You would need a pressure of at least 7.333×10^9 Pa (Hope I did the math right.) Which is a pretty immense pressure. But since the bulk modulus of water is non-linear with pressure, the real pressure is probably much much higher. I can't find info on how non-linear. Ariel. (talk) 10:57, 28 March 2011 (UTC)

I remember seeing an old film clip about what must have been the Bathysphere or Benthoscope returning from the deeps after a test run. When its hatch bolts were gingerly loosened, a huge quanity of water gushed out under pressure, seemingly several times the volume of the sphere. So, yes. In fact anyone could do this - throw a 1l weighted plastic bottle of water into the deep ocean, and when it eventually reaches the bottom it should be considerably crushed. 92.15.14.99 (talk) 11:56, 28 March 2011 (UTC)

Nah, that's incorrect. Even at the bottom of the ocean water density increases by just a few percent. Dauto (talk) 14:46, 28 March 2011 (UTC)

Got any evidence for that please? 92.15.14.99 (talk) 15:10, 28 March 2011 (UTC)

Properties of water#Compressibility. DMacks (talk) 15:35, 28 March 2011 (UTC)

I saw what I saw. The Challenger Deep is about 11km deep. 92.15.14.4 (talk) 20:24, 28 March 2011 (UTC)

You saw what you saw and you don't know what you saw. At that depth the density will still be only a few percent higher. Dauto (talk) 20:44, 28 March 2011 (UTC)

Probably an optical illusion. A thin curtain of water mixed with air to form bubbles might look like a lot more than it really is. StuRat (talk) 20:54, 28 March 2011 (UTC)

On reflection it may have been the air inside that became very compressed and forced the water out, and the sphere wall could have been thinner than I expected. 92.29.126.172 (talk) 13:41, 29 March 2011 (UTC)

Now you're making sense. Dauto (talk) 13:56, 30 March 2011 (UTC)

Methanopropylenes

Hi. I recently had a dream about "methanopropylene" (I know, I'm so weird). The name could refer to either a propylene plastic impermeable to polar methano-molecules such as methanol in gaseous or liquid form and to chemicals produced by methanogens, or polymers derived from methanols. The only Google item I could find relavent to my topic, in fact the only website in existance remotely related was this, but any idea what type of chemical methanopropylenes would constitute and what potential they have? Thanks. ~AH1^(TCU) 11:46, 28 March 2011 (UTC)

School time lays long in the past and probably they also changed the way to name things, but when I hear of methanopropylene I think of H₂C=C(CH₃)-CH₃, that is propylene where the middle H is substituted by CH₃. I know the CH₃ would be in the middle for otherwise the longest unforked C-chain would consist of 4 C-atoms and the basic name would be derived from butan and it would be butylene. 77.3.138.240 (talk) 13:17, 28 March 2011 (UTC)

That would be methylpropylene (IUPAC name methylpropene); the methano- prefix isn't very common, but it does show up in the names of some amino acids, like 2,4-methanoproline and 2,4-methanoglutamic acid, see [2]. In these cases, methano- refers to a bicyclo system with a cyclopropane ring as part of it; "methano-" means you have bonded one carbon to two neighboring carbons in the main, named chain or molecule. Under that derivation, methanopropylene would likely be an alternate name for Methylcyclopropane. --Jayron32 14:19, 28 March 2011 (UTC)

So that methano-ethane would be equivalent to cyclopropane? 77.3.138.240 (talk) 14:42, 28 March 2011 (UTC)

Actually, probably methanoethylene, as the compound would be formed from ethylene (IUPAC name ethene) rather than ethane, which is pretty much unreactive. As I said above, the methano- prefix is non standard, and you wouldn't find the term in any IUPAC-standard name, AFAIK. --Jayron32 00:07, 29 March 2011 (UTC)

time 2

in my March 26 question about "time", most of the answers talk about watching a distant clock move (pass time) at some multiple of my clock. Wouldn't that mean that as I approach the clock the light is getting to me faster than c? —Preceding unsigned comment added by 165.212.189.187 (talk) 13:45, 28 March 2011 (UTC)

The light is not approaching you (i.e. as measured in your frame) faster than c. However, if there is another observer who sees you moving toward the light source, then because in his frame the speed of light is also c (no contradiction here because time is not absolute), he would see that the distance between where in his frame the light front is, and where you are, is shriking faster than c, however this is not a relative speed, so there is no contradiction with relativity here.

I think it would be a good exercise for you to work out this in detail and derive the Lorentz transform equations, it is quite easy to do. Count Iblis (talk) 14:17, 28 March 2011 (UTC)

So what explains me observing the minute hand of the distant clock move faster than mine, does mine slow down? —Preceding unsigned comment added by 165.212.189.187 (talk) 15:13, 28 March 2011 (UTC)

Dominant effect: As you are approaching the clock, the time needed for the light to travel from the clock to your eyes is becoming less. So, the time delay diminshes as a function of time, making the clock look like moving faster. This is just the classical doppler effect. There is then a small relativistic correction to this because of time dilation. Count Iblis (talk) 16:21, 28 March 2011 (UTC)

Cow dung to absorb gamma rays

A leading newspaper from India, quoting a physics professor, says that "Cow dung, in fact, can absorb all the three rays -- alpha, beta and gamma... If the outer walls of houses are coated with thick layers of cow dung, it will absorb the gamma rays and in turn people would be safe". Does anyone know how thick should be be this cow dung coating to make people inside the house safe(in the context of a radiation accident). 14.139.128.14 (talk) 13:46, 28 March 2011 (UTC)

Dung consists mostly of water and carbon of some form. I estimate that about 10cm would be sufficient to protect from neutron radiation (as long as you can keep the dung from drying). As for alpha and beta radiation, I cannot imagine any building wall, be it concrete, wood, glass or plastic that can be thin enough to not also protect from this kind of radiation. The best protection from gamma rays is dense matter with heavy nuclei. I doubt heavily that dung can protect from it, unless several meters thick. Any shielding whatsoever could not protect from radioactive materials coming in with air, food and water. To put it short: I think that's plain nonsense. If you would use pig dung instead, you could at least assure that no one gets hurt by radiation inside the building because everyone would have left due to the smell. 77.3.138.240 (talk) 14:27, 28 March 2011 (UTC)

Concur with the above, cow dung would not offer more protection then soil of the same thickness against gamma radiation. I smell BS. Googlemeister (talk) 16:20, 28 March 2011 (UTC)

Very, very literally BS. SDY (talk) 19:12, 28 March 2011 (UTC)

Also bogus/nonsense claims? DMacks (talk) 16:25, 28 March 2011 (UTC)

The article is nonsense. And on top of that direct radiation is not something anyone needs to worry about unless they are building (or working in) a reactor. Even if cow dung was a miracle shield, and blocked radiation 100% it would be worthless. The problem is ingesting radioactive elements - the resulting radiation is internal, not external. Ariel. (talk) 21:47, 28 March 2011 (UTC)

Psychology of spending

I wonder if there's a name for the thing I'm thinking about. I see a small one-serving pack of M&M's on the shelf at the store selling for $1.35 and could easily imagine people having no problem with that and buying it. But if I imagine myself trying to sell that pack for that much as an individual or even buying the same from another individual, that price feels too high. But it's the same exact product. It's not that it's used- I get that there's probably an association between individuals and used objects, but I still get this feeling if it's still sealed. Is there a name for the feeling that if it's a real business doing the selling, the higher prices than what I'd ever pay an individual are OK? 20.137.18.50 (talk) 14:29, 28 March 2011 (UTC)

In the same vein, some people (i.e. me) prefer buying electronics or appliances at a large retail supplier to buying them at a small independent one (unless the price premium is TOO great), despite the fact that the products are identical and would be under the same warranty from the same manufacturer. It's the same for brick-and-mortar vs online stores. I'd be interested to read the replies. Zunaid 15:13, 28 March 2011 (UTC)

If what you describe amounts to "I'd pay $1.35 for these M&M's from a reliable retailer like MegaLoMart, but if I were buying them off a dodgy geezer like 20.137.18.50 I'd expect they're either rubbish or hooky, so I'd want a major discount" then that would be Halo effect. Similarly one can buy stuff from Fortnum and Mason that's much the same as you'd get from Tesco, but at a significantly higher price, which I think is called "brand premium". -- Finlay McWalter ☻ Talk 15:14, 28 March 2011 (UTC)

Expanding on that, I'd also point to information asymmetry, The Market for Lemons, and the notion of "the bad driving out the good" in a market. If a random stranger offers to sell me candy, I don't know anything about him, his storage practices, his inventory turnover, or his approach to hygiene. He may or may not have an incentive to keep me happy as a customer; is he interested in repeat business, and is there any way for me to assess that? Because I don't have access to all that information – whereas I can make (better) guesses about it for a regular retailer – I am apt to discount the perceived value of the candy. TenOfAllTrades(talk) 16:43, 28 March 2011 (UTC)

The stuff you can buy in Harrods is the same as what you can buy elsewhere at cheaper prices. Same with many other shops. 92.15.14.4 (talk) 20:10, 28 March 2011 (UTC)

Physics of insect wings

Can someone can translate the equations from here to math equations (you know, <math>) on Wikipedia so I can include them in the article, Wing (insect)? Bugboy52.4 ¦ =-= 17:04, 28 March 2011 (UTC)

$h={\frac {g(\Delta t^{2})}{2}}$ and $\Delta t^{2}=\left({\frac {2h}{g}}\right)^{\frac {1}{2}}$ are what the first two say, but surely it doesn't mean that? I think Δt is intended in the second one. (I'm also not sure how to do bigger brackets than one line's worth.) Changed. Grandiose (me, talk, contribs) 17:16, 28 March 2011 (UTC)

You're right. The units are inconsistent. The equation should read $\Delta t=\left({\frac {2h}{g}}\right)^{\frac {1}{2}}$. Dauto (talk) 17:38, 28 March 2011 (UTC)

Thank you! And one more thing, if you can, there are a few mentioned after about elasticity, can you do those two? Bugboy52.4 ¦ =-= 17:41, 28 March 2011 (UTC)

Which page? Looks like it might be on 78 or 79, which aren't available on that preview (for me, at least). [The first two equations are straightforward rearrangements of each other; might not both be useful depending on context.]Grandiose (me, talk, contribs) 17:53, 28 March 2011 (UTC)

79 I believe. Bugboy52.4 ¦ =-= 18:05, 28 March 2011 (UTC)

I wasn't able to access page 79 in that edition using Google Books (too many people tried, perhaps?), but I was able to access the second edition of that book on Amazon, and searching for "elasticity" led to this equation (eq. 6.11, in section 6.5 "Elasticity of Wings") for the energy E stored in the stretched resilin:

$E={\frac {1}{2}}{\frac {YA\Delta \ell ^{2}}{\ell }}$

Is that what you needed? -- Scray (talk) 00:15, 29 March 2011 (UTC)

Wonderful, what pages can you get with Amazon, I'm going to look more to find those pages. Bugboy52.4 ¦ =-= 01:36, 29 March 2011 (UTC)

Just search for the book, then "Look inside", and search for a term. You can choose the hit you want to view and you'll see a couple of adjacent pages. No doubt they'll be on to you if you access too many... -- Scray (talk) 01:59, 29 March 2011 (UTC)

Headlights of a spaceship if turned on relative to two different observers

Lat a spaceship with its remote controlled headlights is moving with 0.9c relative to observer on asteroid who is not co-moving.

1- Onboard observer turned on the headlights of his spaceship with the help of a remote control device by sending a signal (pulse) from the back of ship to it's front

2- While due to the high speed of ship a signal (pulse) will still be moving inside the ship relative to asteroid observer.

Thus would the headlights be turned on at the same time for both onboard and asteroid observers if the perception distances are ignorable

Perception distances: The distance travelled by headlight

b/w headlights and onboard observers AND b/w headlights and asteroid observer 68.147.41.231 (talk) 17:52, 28 March 2011 (UTC)Eccentric Khattak#1-420------[GO]

See relativity of simultaneity for a discussion about this kind of thing. --Tango (talk) 22:17, 28 March 2011 (UTC)

I asked above in regard to sub section " The train and the platform thought eperiment" of the article. I got unsatisfactory answers from forums therefore still its difficult for me to the fathom.

The same senario but the other way

Let aforementioned remotely control spaceship is moving with 0.9c relative to stationary observer on asteroid. Onboard observer sends a stoping signal (pulse) from the back of ship to it's front with the help of a remote control device.

1- For onboard observer: A pulse would hit the front and thus stopped the ship earlier than asteroid's observer

2- While due to the high speed of ship a pulse will still be moving inside the ship relative to asteroid observer

Since a pulse would arrived the front at two different timing relative to aforementioned observers therefore would the ship be stopped at the same time at the front of asteroid for both observers.

The purpose of this post is to share knowledge and shouldn’t be considered offensive.68.147.41.231 (talk) 00:15, 31 March 2011 (UTC)Eccentric Khattak#1-420

Vanadium oxidation

Does it make the pentoxide or vanadium(IV) oxide? --98.221.179.18 (talk) 18:35, 28 March 2011 (UTC)

Vanadium oxide indicates both the (4+) and (5+) oxides, along with several others, as well as the possibility of non-stoichiometric oxides, indicating multiple oxidation states within a single crystal lattice. --Jayron32 00:03, 29 March 2011 (UTC)

Game theory: paying ransom

Imagine that something worth $1000 has been stolen. The thief demands $900 from you. You thing: OK, I pay, it's still $100 on my favor. After you pay, the thief demands $900 again. Do you pay again? It's still $100 cheaper than buying anew. (the first $900 are now sunk costs). Quest09 (talk) 18:45, 28 March 2011 (UTC)

If your country takes your taxes but still refuses to protect your property rights then you should consider hiring Juri Kalashnikov instead of paying indefinite ransom . (Millions for defense, but not one cent for tribute) 77.3.138.240 (talk) 19:22, 28 March 2011 (UTC)

What's missing from this apparent paradox is an assessment of risk. That resolves the paradox.

In the first scenario, let's say you were 95% certain that the ransom would be honored. That puts you at a $950 'expected' payout on your $900 investment.

During the second ransom, you know that your original assessment of the risk was wrong. Now you're much less sure that the ransom will be honored. Let's say now you're only 25% certain that they'll honor the second random after not honoring the first ransom. That gives you a $250 'expected' payout on a $900 investment. Clearly you should walk away.

In other words, the sunk-cost doesn't carry over from one 'round' to the next, but previous 'rounds' do change your expectations of how the other party will act.

(This all assumes that there's no better options available. For example, If you believe that there's a 50% chance that law enforcement can retrieve your item at no cost to you, then that is the correct choice because it offers an expected $500 profit.) APL (talk) 19:39, 28 March 2011 (UTC)

(ec) 50 percent chance of law enforcement? "Har Har Har" Excuse me, from what I personally experienced in Germany, my advice is: forget about it. 77.3.138.240 (talk) 19:50, 28 March 2011 (UTC)

As an alternative, the money that would have been spent on the ransom could also be spent in hiring private detectives and/or posting a reward. If the payment is contingent upon the item being recovered, then you are guaranteed that some effort will be made to recover the object, unlike with police, who may not much care about such a tiny item, since they won't get a share. StuRat (talk) 22:30, 28 March 2011 (UTC)

I wouldn't say your assessment of the risk was wrong. If you had thought there was a 100% chance they would give you your money, then you would have been wrong, but just because the 1 in 20 chance happened doesn't mean it was more likely than 1 in 20. We're not talking about a random occurance, anyway, we're talking about a definite thing (either they are planning to give you your money or they aren't - they aren't going to toss a coin to decide), just one that you have incomplete information about. Getting additional information doesn't mean you made a mistake before. --Tango (talk) 22:26, 28 March 2011 (UTC)

If you were aware of the idea of sunk costs then you could, but the kidnappers refusal to return the goods the first time would give you a lot of information about them, so you would probably think they would repeat the same trick again, and refuse. A clever thief would ask for a lesser amount the second time, to tempt you. I think J. Paul Getty was probably right about refusing to pay a ransom for John Paul Getty III. 92.15.14.4 (talk) 20:01, 28 March 2011 (UTC)

Isn't the original theft already a "sunk cost"? Would you trust a random person, who admits that he is a thief, who offers to sell you $1000 worth of goods for $900? Additionally, of course, one worries that by doing business with a scam artist, he is branded as a sucker - just like buying something from a spammer. Conversely, an attack on the thief that succeeds has substantial prestige value. Wnt (talk) 01:44, 29 March 2011 (UTC)

"Conversely, an attack on the thief that succeeds has substantial prestige value." What kind of attack did you have in mind? How would this help you get your stuff back? Its usual to do the paying of the ransom secretly, so being seen as a sucker or gaining prestige would not apply. 92.29.126.172 (talk) 13:51, 29 March 2011 (UTC)

The secret might get out, or that same thief might target you again, or tell one of his thief friends about it, who then target you. So, the cost of the increased future likelihood of theft must be considered in the equation. The original theft could even be a test case, to see how you react to ransom demands, so the thief will know whether to go ahead with kidnapping your kids, as planned. StuRat (talk) 18:19, 29 March 2011 (UTC)

In a law-abiding society one might pay the thief with an exploding dye-pack and a police pursuit, or in a less lawful one, with a pipe bomb; either way, the ensuing damage to the thief is apt to become known and dissuade further attacks. Wnt (talk) 03:43, 30 March 2011 (UTC)

Never heard of revenge or vendetta? 92.15.1.33 (talk) 16:20, 30 March 2011 (UTC)

Smart kidnappers know not to return "the goods" (if at all) until they have completely gotten away, by telling you where to go pick it up. They might also use an innocent "patsy" to pick up "a package somebody left for me". StuRat (talk) 05:05, 30 March 2011 (UTC)

You learnt that off the movies. 92.15.1.33 (talk) 16:20, 30 March 2011 (UTC)

And so did the smart kidnappers. StuRat (talk) 16:24, 30 March 2011 (UTC)

Question regarding extraterrestrial radio pulses

I was watching an interview with Arthur C. Clarke (co-writer of 2001: A Space Odyssey) before the movie's 1968 premier in which he said:

"In the last few weeks there has been tremendous excitement among the astronomers over the extraordinarily precise and rhythmic radio pulses coming from the direction of a point between Vega and Altair. Which may yet turn out to have a natural explanation, but its periodicity and characteristics are so extraordinary that no explanation as yet seems very feasible."

I'm picking up some references to 1967 signals picked up from Vega and Altair...but whatever happened? Have these been explained? Thanks. WordyGirl90 19:44, 28 March 2011 (UTC)

The timing and location look right for it to refer to the first pulsar to be discovered. AndrewWTaylor (talk) 19:49, 28 March 2011 (UTC)

There was the Wow! signal But that was in 1977, not in 1967. Googlemeister (talk) 19:50, 28 March 2011 (UTC)

The LGM-1 was from 1967 and is probably what Clarke was talking about. Googlemeister (talk) 19:56, 28 March 2011 (UTC)

That would have to be it...correct constellation, too. Thanks :) WordyGirl90 20:19, 28 March 2011 (UTC)

Interface for communicating with blind people

Hi all. I'm writing a short novel where the protagonist, who is blind, uses a technological device that accurately scans his surroundings and sends this information back to him. The problem is that I can't imagine exactly how I would transmit this information to the blind user. Using a synthetic voice would interfere with 'real', useful sounds. Maybe using a pad in the hand with vibrations/pressure/heat that conveys this information? Please, help me with my brainstorming! Thank you very much. --Bliviinc (talk) 21:49, 28 March 2011 (UTC)

There were experiments that had a head-mounted grayscale camera. It converted the image to sound by scanning a line at time. Left-to-right was represented by low tones to the left, and high tones to the right; black was quiet for that frequency, white was loud. I'm not sure how the start of each frame was represented; lets say a click.

Thus

• A vertical line white line on a black background is a solid tone; lower in tone to the left
• A horizontal line is sudden burst of white noise, the rest is silence. The closer to the click the higher up the line is.
• A top-left to bottom-right line is a rising tone
• A top-right to bottom-left line is a descending tone.

From memory, the experiments were successful enough for the subjects to navigate using the device. I'm not sure if there were different sounds (views) for each ear or not. It probably started with the same tones to each ear if there was eventually two cameras/tones. CS Miller (talk) 22:08, 28 March 2011 (UTC)

How about a device that has little bumps that raise up to form the equivalent of a black and white image of the room ? There already exists a device which raises bumps to form Braille letters. As an alternative, instead of the bumps being raised based on the darkness/lightness of the object, they could be raised or lowered based on distance from the device, to created a 3D image of the room, at perhaps 1/1000th the depth of the room (it would be nice if this ratio was adjustable for large and small rooms). Since the blind person would be constantly running their hand over it, it should be washable, as it would accumulate oils and dirt. Perhaps a removable flexible surface on top could be washed or replaced, as needed, with the expensive "guts" remaining dry. StuRat (talk) 22:20, 28 March 2011 (UTC)

I recall a TV show featuring someone blind from birth who had developed his own sense of echo location, making his own audible clicks. If someone has been blind from birth, their senses have had a longer time to compensate for the loss of sight. PЄTЄRS J V ►TALK 22:25, 28 March 2011 (UTC)

I recall a similar TV show. I remember a young boy finding and identifying a fire hydrant by clicking. --Tango (talk) 22:48, 28 March 2011 (UTC)

Personally, I'd think the smell of dog pee might be a clue. :-) StuRat (talk) 22:53, 28 March 2011 (UTC)

This site: http://www.seeingwithsound.com/ they have a demo and you can practice playing tic-tac-toe by sound alone. Ariel. (talk) 22:58, 28 March 2011 (UTC)

That's a heck of a lot less challenging than navigating through a room, though. StuRat (talk) 23:00, 28 March 2011 (UTC)

The tic-tac-toe is just a demo for sighted people. The device is actually used for navigating rooms. Ariel. (talk) 23:20, 28 March 2011 (UTC)

A device far cooler then using sound already exists. Vespine (talk) 23:04, 28 March 2011 (UTC)

Great ideas!! I particularly like your idea, StuRat. Apparently, a big problem blind people face and that most "navigating aid" devices can't detect are slopes and steps, instead of massive obstacles. How would you communicate those to the user with your bump-grid? --Bliviinc (talk) 23:40, 28 March 2011 (UTC)

Well, if the difference in height of the bumps wasn't enough when looking at the whole staircase or slope, perhaps it could be focused on an individual step or section of the ramp, and would automatically scale the depth so that the closest objects in the view had bumps 100% up, and those farthest away in that view would have bumps 100% down. StuRat (talk) 23:54, 28 March 2011 (UTC)

I think that the main problem is detecting those on the fly, without having to stop and focus on them. Maybe additional, always-zoomed bumps? --Bliviinc (talk) 23:59, 28 March 2011 (UTC)

Just to be explicit, the bump-grid concept is actually the basis of the device that Vespine pointed to above. Looie496 (talk) 00:01, 29 March 2011 (UTC)

I also once read about a blind guy who could use echo like a bat, but I suppose that while all people can use echolocation to some extent only chosen few can use it to navigate. How about full body suit that warms or puts pressure on persons skin if it senses an obstecle right in front of that spot and the pressure/warmth varies in strenght depending on how close the object is? Also assuming blindnes isn't caused by brain damage artifical eyes or neural interface could work (we're talking sci-fi short story, right?). ~~Xil (talk) 00:20, 29 March 2011 (UTC)

Actually, no, they already have that. But it's black-and-white, low res, and requires surgery and training, so not ready for mass-marketing yet. StuRat (talk) 00:31, 29 March 2011 (UTC)

You mean artifical eye? I am aware, but the technology has only just started to develop and there seems to be some promise in it. OP said it is for a story, but hasn't given any further details on setting of his story, so I am assuming it is sci-fi i.e. that it dosen't need to exist or must be producable with current technology ~~Xil (talk) 01:13, 30 March 2011 (UTC)

Wikipedia has an article about corner reflectors. -- Wavelength (talk) 15:08, 29 March 2011 (UTC)

How does that relate to the question ? StuRat (talk) 18:16, 29 March 2011 (UTC)

Radar is a technological device, and staircases have corners. -- Wavelength (talk) 19:25, 29 March 2011 (UTC)

So you're suggesting use of radar ? I don't think this question is about getting the room shape info into a device, it's about conveying that info to a blind person. That's the tricky bit. StuRat (talk) 20:39, 29 March 2011 (UTC)

That information can be conveyed by audible signals. (See Geiger counter.)

—Wavelength (talk) 21:48, 29 March 2011 (UTC)

[I am correcting my punctuation. -- Wavelength (talk) 21:50, 29 March 2011 (UTC)]

But how, precisely ? Would you point a beam in various directions and know the distance in that direction from the frequency of the sounds ? Such a system would work, but would also be very slow to use. I have difficulty imagining how a brain not designed for echo-location could use hearing to instantly "see" an entire room in the way that our eyes do. StuRat (talk) 05:02, 30 March 2011 (UTC)

Our Britches (monkey) article is about a monkey, liberated by the ALF, whose eyes had been sewn shut at birth and he had been made to wear a "substitute sensory device". Comet Tuttle (talk) 18:36, 29 March 2011 (UTC)

It says "sonar device", sounds like echolocation again, it does though mention the device being version of "sonicguide", I googled it didn't find anything in particular, but it seems to be sound emiting device attached to cane, here's a similar device: [3] ~~Xil (talk) 01:13, 30 March 2011 (UTC)