Science desk
< June 9	<< May \| June \| Jul >>	June 11 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 10

Liquid air energy storage

Thermal energy storage doesn't mention condensing and cooling air to a liquid, storing it, and then boiling it off to recover stored energy. How efficient is that for power storage? I know pumped hydro is about 80%, but it doesn't have a very high capacity on flat terrain. What I really want to know is whether building water towers for pumped hydroelectric is more cost efficient per kilowatt hour than building giant thermos tanks for condensing liquid air. 71.212.248.104 (talk) 04:45, 10 June 2012 (UTC)[reply]

Insulating and maintaining liquid air isn't easy or efficient. In order to keep it cold enough and under enough pressure to be useful will make the system vastly less efficient than pumped hydroelectric. Besides, you don't need to build tanks for pumped hydroelectric. You just need to dig a big hole at high elevation. --Jayron32 04:53, 10 June 2012 (UTC)[reply]

Ah-ha! Clearly you're right, because for pumped hydro on flat terrain you only need a big hole in the ground, since the gravity pressure is only necessary at a generator turbine which could be at the bottom of the hole. (Unlike everyone's plumbing which is why water towers need to be in the air, or tanks on hills, etc.) 71.212.248.104 (talk) 05:01, 10 June 2012 (UTC)[reply]

You may be interested in Pumped-storage hydroelectricity. Of course, like other forms of hydroelectric, it only works in areas of the proper relief. You can't build an efficient hydroelectric plant in a wide open plain for any purpose. --Jayron32 05:07, 10 June 2012 (UTC)[reply]

... but if you build it on the coast you can get "more than 100% efficiency" with careful tidal timing (really gleaning energy from the earth-moon orbital system). Dbfirs 08:42, June 10, 2012 (UTC)

Um, what I'm saying is, you just need two (sets of) water tanks, one far underground, and one at the surface, which is fairly inexpensive and would work in Kansas. That is much less expensive than using a water tower, which is the traditional way municipal water pressure is powered in flat areas. You can't predict water usage and you can't predict electricity usage, but you can shape the load with pumped storage tanks in both cases, for only 20% overhead lost to heat at the turbine, pump, and piping in the case of electricity. (Modern engineers would probably want to try to recover some of that lost heat, since it's fairly localized.) 71.212.248.104 (talk) 10:52, 10 June 2012 (UTC)[reply]

If you happen to have a convenient deep underground cavern with easy access, then that idea sounds workable, but you are limited by the size of the underground tank. Dbfirs 11:29, 10 June 2012 (UTC)[reply]

Subjective experience and age

How does subjective experience--by which I mean consciousness--change with age? I'll give a few examples to indicate what I'm looking for. Children are easily excited, and their emotions are more extreme. Children are happier, sadder, and angrier than adults in happy, sad, and frustrating situations, respectively. Teenagers and people at mid-life tend to be more depressed. The young perceive time as passing much more slowly older people; one year seems like an eternity to a 6 year old, but passes quickly for a 70 year old.

Does anyone know of a more complete list? My examples above are mostly based on my experience, which is limited because I'm quite young and represent only 1 sample point. --140.180.5.169 (talk) 09:26, 10 June 2012 (UTC)[reply]

I don't know of a more complete list. Except for a couple of things which I'll note, I think you are wrong anyway. I have passed retirement age. I dissagree that children have stronger emotions - what changes is perception about what is sad, happy etc. To a child, not getting your favorite food today can be something to cry over. To an adult, it's unimportant. This is not about strength of emotion - its about intelligence and experience. Children know that by over-acting, they can persuade adults. Acting angry or sad is not being angry or sad, even if you convince yourself. Psychologists have written learned papers about depression in teenagers. Never the less, I think it's nonsense. Having been through it, depression when a teenager is not deep and is quickly overcome. What's different for teenagers and adults in recent years, is that doctors will more readily prescibe for it, and that is a bad thing. On the other hand, depression is recognised as real these days, and that's a good thing. You won't know what sadness is until you loose a loved one after years of being together.

One thing that DOES change is perception of size and distance. When I was about age 3 to 5, my mother and I used to go and spend a week now and then with grandfather at his house, in another city. When there, Grandfather would walk me to a shop and buy me an icecream. It seemed a long walk. We also used to go to the beach - another long walk. Grandfather died when I was 5. When I was 18, the company I worked for sent me to that city. I decided to retrace old steps. I was greatly surprised that the distance to the shop was 1 block! The distance to the beach was 1 block! Recently, my old primary school was opened as a tourist office. I had a look. I was suprised how small the rooms were.

You are correct that time passes more slowly for children.

Another thing that changes is your view of the general competence of adults. When you are a child, you think adults are 100% capable. When you are a late teenager, adults frustrate you whith their slow decision making and inability to learn new things quickly. When you get to retirement age, your perception changes - older people now seem competent, but teenagers seem rash and impatient. But, thinking about it objectively, those pesky teenagers are right!

When people get really old and start to loose their faculties, then the more deeper and more evolutionary early parts of the brain take over. Then, emotions can get rediculously strong. I had a relative who lived in an old-folk's home - the sort where nurses were on duty 24 hours a day. I was there once when the kitchen was 30 minutes late in serving lunch. A number of inmates staged a riot (in their wheelchairs, in slow motion)! You'd never get that at any other age, and you'd never get that in people who are mentally fit - they would just accept that sometimes things go wrong.

What does change as people get older is the rate at which emotions can change. In management training, I was taught that when given bad news, people go thru 5 stages of grief: disbelief, why me/anger, sadness, resignation/acceptance (sometimes bargaining), and finally, seeing an advantage. See http://en.wikipedia.org/wiki/5_stages_of_loss. Some psychologists don't accept this, but you get that. In my experience it is right - it has helped me a lot in counselling employees and family. Now, children can go thru all 5 stages in seconds. Teenagers can take longer. Middle aged folks can take months. Some folks remain stuck at one stage - that can happen with young adults, but not very often. I don't think children ever get stuck.

Wickwack124.182.162.50 (talk) 10:37, 10 June 2012 (UTC)[reply]

"One year seems like an eternity to a 6 year old, but passes quickly for a 70 year old" is something that everyone says, but personally, I don't think it's true. What is true as we age is that events we remember can be longer ago, and that any given length of time is a smaller fraction of our total experience. When people say "time goes by so fast these days!", they're always reminiscing about the past, not looking to the future; "1 year ago" doesn't seem like such a big deal now as it did when you were 6, but on the other hand "next week" will take just as long to get here now as it did then. FiggyBee (talk) 14:36, 10 June 2012 (UTC)[reply]

I would disagree with that point, the time until next week does grow shorter with age, the "are we there yet" question shows a slower movement of future time as well. The OP should look for information at Gerontology or in these journals. 65.95.22.197 (talk) 17:02, 10 June 2012 (UTC)[reply]

I have to agree with IP 65. Knowing you had to wait A WHOLE HOUR!!! for something as a kid was torture that took forever. Nowadays that's hardly even enough time to get ready for anything. μηδείς (talk) 18:00, 10 June 2012 (UTC)[reply]

For a 5-year-old a year is 1/5th of their entire lifetime, for a 70 year old it's only 1/70th. Roger (talk) 20:27, 10 June 2012 (UTC)[reply]

Reaction times do slow down with age ( A Literature Review on Reaction Time by Robert J. Kosinski

Clemson University , http://biology.clemson.edu/bpc/bp/Lab/110/reaction.htm ) and working memory capacity decreases as well. So I think it is fair to say that subjective experience indeed changes with age. 129.2.171.55 (talk) 22:26, 10 June 2012 (UTC)Nightvid[reply]

2012 event

will the 2012 event eventually kill us all or not??????????!!!!!!!! — Preceding unsigned comment added by 77.35.15.169 (talk) 12:24, 10 June 2012 (UTC)[reply]

I changed your heading from the non-informative "!!!!!!!!!!!". I guess you refer to something from 2012 phenomenon which says: "Scholars from various disciplines have dismissed the idea of such cataclysmic events occurring in 2012." PrimeHunter (talk) 12:31, 10 June 2012 (UTC)[reply]

Not only that, but recent archaeological discoveries have demolished the notion that the Mayans considered 2012 to be the "last" year. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:34, 10 June 2012 (UTC)[reply]

There never was any evidence that the Mayans considered 2012 the last year. They computed numbers up to a point far into the future, far more than they would ever need. They stopped computing at the end of a particular mathematical cycle because it made rational and aesthetic sense to end there rather than some point chosen at random. You can find many places where there are ordinary Gregorian calendars, or the precise dates of Easter, computed for a number of years into the future, but they all stop at a certain point, too. Nobody has ever interpreted this to mean a prediction of the end of the world (!) at that point, and they should never have done so for the Mayan calendar either. -- ♬ Jack of Oz ♬ ^{[your turn]} 23:51, 12 June 2012 (UTC)[reply]

Microsoft Excel can only show times up to 31/12/9999 23:59:59 and after that every time is show as ################. Surely this means that some brilliant soothsayer/programmer foresaw that the world will be reduced to a series of hashes at that point. Or maybe there will be free hash browns. 203.27.72.5 (talk) 01:48, 13 June 2012 (UTC)[reply]

From a scientific perspective, nothing unusual, besides an astronomical observation, should happen on 21 December. Don't believe every thing you hear. Plasmic Physics (talk) 13:38, 10 June 2012 (UTC)[reply]

Most scientists believe that every single human alive on the 21st December 2012 will die, either on that day or at some point in the following months or years. LukeSurl^{t c} 14:56, 10 June 2012 (UTC)[reply]

But not as a result, direct or indirect, of "the 2012 event". FiggyBee (talk) 14:58, 10 June 2012 (UTC)[reply]

Quite. --LukeSurl^{t c} 15:06, 10 June 2012 (UTC)[reply]

See section 3 page 12 and further of this article. The universe is making a transition to a state of exact supersymmetry, we are now in the false vacuum state, after the transition we'll be in the real vacuum. A long time ago, a bubble containing the exact supersymmetric vacuum nucleated and started to expand at the speed of light. We're now just a quarter of a light year from the edge of that bubble. When we cross the boundary of that bubble, a huge amount of energy will be released killing all of us in a fraction of a second.

However, since we all have an infinite number of identical copies, the closest one located about about 10^{10^29} meters from here see here, and they may be further away from the edge of the expanding bubble that exist there, they may survive into next year. Because these copies are identical to you, you will actually survive as your copy without having any knowledge about being killed here. So, it will look like this was all a doomsday myth. Count Iblis (talk) 16:29, 10 June 2012 (UTC)[reply]

I can personally affirm that as the absolute truth, Count Iblis. because this has all happened befor .I know because I was there.190.148.132.194 (talk) 17:15, 10 June 2012 (UTC)[reply]

Citation required. 84.209.89.214 (talk) 18:04, 10 June 2012 (UTC)[reply]

LOL (at both the two most recent posts immediately above) HiLo48 (talk) 00:03, 11 June 2012 (UTC)[reply]

Could we escape this fate if the bubble nucleated at such a distance from us that the universe's expansion would keep it from ever reaching us? 203.27.72.5 (talk) 01:42, 11 June 2012 (UTC)[reply]

Yes, making certain assumptions about the expansion of the universe. See Observable Universe. Of course, we couldn't see the described bubble coming if it was moving at the speed of light - the image wouldn't reach us until the bubble hit us. Schild's Ladder is a book involving such a bubble expanding at half light speeed. 209.131.76.183 (talk) 13:03, 11 June 2012 (UTC)[reply]

Hold on. Tomorrow will be there after it all blows away. (video) DriveByWire (talk) 14:27, 11 June 2012 (UTC)[reply]

How would Uranus have been pronounced in the 1780s / 1790s

Johann Elert Bode suggested the name Uranus. However, the Wikipedia (and many other places) always refer to this as the 'Latinized name'. I assume this is intended to distinguish it from the Greek pronunciation of the name. (Something like 'oo-RA-nos') My question is, how would an english speaker in the 1780s/1790s have pronounced the latinized version of the name Uranus? --CGPGrey (talk) 15:22, 10 June 2012 (UTC)[reply]

Not a definitive answer, but Greek οὐρανός would have been pronounced, in English, with the stress on the first syllable (OO-rah-nohs), since the vowels in the last two syllables are short. I assume that the Latinized version would have been pronounced something like YOO-ruh-nuhs if the normal rules for such things were being followed. Deor (talk) 17:41, 10 June 2012 (UTC)[reply]

We don't have a speech recording from the 18th century. Those who spoke of the planet would likely have known enough Greek to argue about how the ancient Greeks pronounced Ouranos. Since both the English words "anus" and "your" were current at the time I'm sure someone could have thought of a joke that would have been for once original. Anyone embarassed by that hilarity might persist in calling the planet Georgium Sidus (King George III's star), as did British Victorian nautical almanacs as late as 1850. 84.209.89.214 (talk) 17:55, 10 June 2012 (UTC)[reply]

New question to add on to this: what about georgium sidus? I assumed it would be with a 'g' as in George sound, but I've come across a few sources saying it with a 'y' sound at the start. --CGPGrey (talk) 13:05, 11 June 2012 (UTC)[reply]

Old newtonian problem solved?

Resolved

Is this accurate: http://www.dailymail.co.uk/news/article-2150225/Shouryya-Ray-solves-puzzles-posed-Sir-Isaac-Newton-baffled-mathematicians-350-years.html

and has it been verified by others? Bubba73 ^{You talkin' to me?} 15:41, 10 June 2012 (UTC)[reply]

From the linked report one can gather only that someone (who?) has hailed a schoolboy a genius for "cracking puzzles (what?) that have baffled the world of maths (who?) for 350 years. I see no more to support this claim than an article title translated as "Analytical solution of two unsolved problems in fundamental particle dynamics" on a PC screen, and the utterly non-newsworthy information that "scientists can now calculate the flight path of a thrown ball and then predict how it will hit and bounce off a wall". Poorly educated journalists should keep away from subjects that they are not equipped to understand. 84.209.89.214 (talk) 17:38, 10 June 2012 (UTC)[reply]

Actual experts weight in here. Someguy1221 (talk) 19:22, 10 June 2012 (UTC)[reply]

Thank you, that helps a lot. It seems like just about every time there is something like this, it doesn't quite pan out. Bubba73 ^{You talkin' to me?} 21:50, 10 June 2012 (UTC)[reply]

physics

what distance of gravitional field? prove that — Preceding unsigned comment added by Krishan chodhary (talk • contribs) 15:47, 10 June 2012 (UTC)[reply]

Isaac Newton obtained his law of gravitation in which gravity works over unlimited distance, by observation and experiments that are readily demonstrated on laboratory scale. The law also allows planet movements to be explained. We cannot explain fully how gravity works and in extreme cases, such as over great distances and velocities aproaching the speed of light, Newton's classical description must be modified by Einstein's geometric theory of curved spacetime. We can provide these references but cannot give you proof of what appears to be a universal Physical constant. 84.209.89.214 (talk) 17:15, 10 June 2012 (UTC)[reply]

Physics numerical

uniform electric and magnetic fields with strength E and B are directed along the y axis

a particle with specific charge q/m leaves the origin in direction of x- axis with an initial velocity Vo

Find a) the co ordinate of the particle when it crosses the y- axis for nth time b) the angle alpha between the particle velocity vector and the y-axis at that moment — Preceding unsigned comment added by 101.214.105.47 (talk) 17:19, 10 June 2012 (UTC)[reply]

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.

Shelled Pistachios lose their flavor?

On Amazon.com there's two types of pistachios they sell, shelled and unshelled.

Shelled http://www.amazon.com/gp/product/B0013NBM5A/ref=s9_qpp_gw_p325_d1_g325_ir06?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-7&pf_rd_r=1BA24ZE30ANCCZK60VPV&pf_rd_t=101&pf_rd_p=470938451&pf_rd_i=507846

Unshelled http://www.amazon.com/Keenan-Farms-In-Shell-Pistachio-Naturally/dp/B001IZIEGS/ref=sr_1_1?ie=UTF8&qid=1339350634&sr=8-1

But the shelled pistachios have significantly worse reviews, with most people saying it tastes worse, and even rancid. They are both made by the same company, so I'm wondering if shelling a pistachio would have a real impact on its flavor, and if so, why? ScienceApe (talk) 17:53, 10 June 2012 (UTC)[reply]

Most foods keep longer if they're kept intact; I don't see why pistachios would be any different. Matt Deres (talk) 18:38, 10 June 2012 (UTC)[reply]

Perhaps the company sorts out the better pistachios to be shelled, since the edible part's appearance could be directly judged by the consumer. -RunningOnBrains^(talk) 00:36, 11 June 2012 (UTC)[reply]

Denver heart attacks

Does Denver have a higher than average rate of heart attacks? What about heart attacks in Denver marathon? Thanks.--Rich Peterson76.218.104.120 (talk) 18:39, 10 June 2012 (UTC)[reply]

Compared to the average rate of heart attacks in which population? Falconus^{p t c} 20:50, 10 June 2012 (UTC)[reply]

Exceeding the RDA of vitamins

I vaguely remember from college that taking excessive amounts of some vitamins and minerals isn't a problem as they can be easily broken down and excreted by the body while others build up and cause damage. If I was to take double/triple the RDA of all the main vitamins and minerals what would be the first symptoms (or should I say which would be most toxic)? Thanks 87.115.195.33 (talk) 19:20, 10 June 2012 (UTC)[reply]

Vitamin A toxicity, see Hypervitaminosis A. The dose that can cause toxicity is the lowest above the RDA for all vitamins and minerals. This may also be due to the RDA being too low for other fat soluble vitamins e.g. vitamin D. The minimum dose of vitamin D that is thought to be capable of producing toxicity is about 40,000 IU/day for many weeks (although the lowest dose that has been observed to actually produce toxicity is 77,000 IU/day). The RDA is just 800 IU/day. However, it may be that the natural dose of vitamin D is 10,000 IU/day as that's what we would get from the Sun were we to spend a lot of time in the Sun at Noon time in the tropics. Count Iblis (talk) 19:43, 10 June 2012 (UTC)[reply]

And some minerals are toxic when taken to excess. Although selenium is required in the human diet, it is toxic in excess. The saem would apply to copper. Graeme Bartlett (talk) 12:28, 11 June 2012 (UTC)[reply]

That's great, thanks for the answers :-) 87.115.195.33 (talk) 21:07, 11 June 2012 (UTC)[reply]

is a twelve minute mile impressive

I know there was a time that the four-minute mile was record-setting, so I'm wondering if a twelve-minute mile is considered impressive IF the person weighs the same as three average-sized people (or if the average weight is obese today, then three averaged-sized people from 50 year ago) for that height and age? This is not a trollish question, if yout think it's bad just answer it matter-of-factly okay. --80.99.254.208 (talk) 20:07, 10 June 2012 (UTC)[reply]

The world record for a mile has dropped a fair bit below 4 minutes now, see Mile run world record progression. For info an average human Walking speed is about 3 miles per hour (a mile every 20 minutes) so a 12 minute mile (5mph) is not quite twice as fast as normal walking pace. Read into that what you will. Over a short distance twice walking pace is nothing, over a mile it does become a question of endurance so I suppose it depends on who you ask...I'm 'relatively' sporty and i'd like to think I can do a faster than 12 minute mile but i've honestly never tried...Maybe I will tomorrow and then reply with my time...might end up embarrassing myself though! ny156uk (talk) 20:43, 10 June 2012 (UTC)[reply]

Yes, in my younger days, I used to walk a mile in 12 minutes (occasionally overtaking slow joggers), but for someone who is three times normal weight, I'd say "well done" and keep up the exercise! Dbfirs 21:25, 10 June 2012 (UTC)[reply]

Yes, a 5 mile-per-hour pace for a full mile would be pretty impressive for a 500 pound man. Looie496 (talk) 22:53, 10 June 2012 (UTC)[reply]

I agree with the other responders. A 12 minute mile is a very brisk walk. Maintaining a very brisk walk for a mile when you are very unfit and overweight is impressive. The important thing is your heart rate - if whatever exercise you are doing is enough to get your heart rate up, then it is worthwhile exercise for you. I would expect maintaining a very brisk walk for a mile would get your heart rate up a lot if you are three times your healthy weight. --Tango (talk) 23:03, 10 June 2012 (UTC)[reply]

I echo everything above. The fitness standard required for those joining the British Army in non-combat roles is a 1.5 mile run in 14 minutes, which equals 9 mins 20 secs for a mile, so you're really not that far away. Remember to put rest days in your programme to avoid joint and muscle injuries. Alansplodge (talk) 23:17, 10 June 2012 (UTC)[reply]

Top racewalkers do a 20km (12½ mile) walk in around 1 hour 17 minutes. This is about a 6.2 minute mile. Now that's impressive. Tonywalton ^Talk 23:35, 12 June 2012 (UTC)[reply]

Is this possible at all? Someone who weighs that much, yet who doesn't collapse during such an effort would have to be very fit, and therefore he would have to exercise vigorously on a regular basis. But then, how could he be so extremely obese? People who exercise a lot don't put on a lot of weight if they eat a lot. Count Iblis (talk) 23:23, 10 June 2012 (UTC)[reply]

By some measures (e.g. BMI) some sportsmen are considered obese. I'm thinking especially of Sir Steven Redgrave and Matthew Pinsent - and nobody would consider those Olympic athletes unfit! A lot depends on what the weight consists of. Muscle weighs more than fat. --TammyMoet (talk) 12:24, 11 June 2012 (UTC)[reply]

That's because the BMI is stupid. It was dreamed up by a dietitian who didn't undertand basic math, and is promoted by psuedo-medical types who also don't understand math. It assumes weight rises as to the square of length. It doesn't. For an object of any shape, if its size goes up in all linear dimensions proportionately, mass will rise according to the cube of any dimension. I am 1.67 m tall and weigh 80 kg. According to the BMI, I am borderline obese. Well, I do look pretty fat, though when I was younger and better muscled from exercise, I didn't look fat but weighed about the same. But I have a cousin who is 2.01 m tall and weighs 120 kg. According to the BMI formula he has the much the same BMI and he too is obese. He's the skinniest person I know. Also, judging by the manual work he does, he's one of the fittest. Also, some people have wide frames. I am 420 mm from shoulder to shoulder, and 350 mm from hip to hip. I used to do weight lifting at the YMCA. The trainer there was the same height as me, but nearly 700 mm across the shoulders. If he tried to get his weight down to 80 kg, he'd collapse from starvation. Wickwack124.182.46.250 (talk) 14:47, 11 June 2012 (UTC)[reply]

Does the Plastic to Oil Machine really work?

I am curious about Japanese inventor Akinori Ito and his invention that turns plastic bags into oil.

What can you do with the oil product once produced?

http://earth911.com/news/2011/02/21/japanese-inventor-turns-plastic-bags-into-oil/

http://www.mnn.com/green-tech/gadgets-electronics/stories/from-waste-to-fuel-invention-turns-plastic-bags-back-into-oil

All my best,

Mark B. Strauss, M.S.

its not real oil — Preceding unsigned comment added by 64.38.226.77 (talk) 20:36, 10 June 2012 (UTC)[reply]

Certainly possible just from the chemistry aspect (not turning it into real crude oil of course, but something similarly combustible) but I can't imagine it's economically feasible, and it certainly wouldn't result in a net gain of energy. -RunningOnBrains^(talk) 00:39, 11 June 2012 (UTC)[reply]

Most plastics can theoretically used as an exothermic fuel source. Although of course, there may still be no net gain of energy after including the cost of converting the plastic to something more efficient/safe/usable. In any event, I have no idea if this machine actually works as advertised. The rate at which newfangled green power generation technologies fade into the aether after appearing in the news has made me extremely skeptical of all such claims. Someguy1221 (talk) 09:51, 11 June 2012 (UTC)[reply]

Note that it would take a huge number of plastic bags to pay off the cost of the device, so it's not something each home should have. StuRat (talk) 23:05, 12 June 2012 (UTC)[reply]

How can I remove moles on my face?

Questions and responses removed because we cannot provide medical advice as a matter of policy. Please consult a qualified medical professional; best of luck. Falconus^{p t c} 00:08, 11 June 2012 (UTC)[reply]

Remove them by going to a dermatologist and seeing what they recommend. StuRat (talk) 15:22, 11 June 2012 (UTC)[reply]

Photoelectric threshold frequency

I'm trying to design sunglasses that convert UV light into solar energy. Is there a cheap material with a photoelectric threshold frequency in the blue-violet (or near-ultraviolet) range? 68.173.113.106 (talk) 20:57, 10 June 2012 (UTC)[reply]

I think you are confusing the photovoltaic effect with the photoelectric effect. To answer you directly, yes, the alkali metals do, however, they would not work for your purpose since they are very reactive with air and water, are not even partially transparent, and do not have an appreciable photovoltaic yield, among other reasons. A suitable substrate for your purpose might be a thin film solar cell. 129.2.171.55 (talk) 21:54, 10 June 2012 (UTC)Nightvid[reply]

Another phenomenon of interest is fluorescence. But if you want your sunglasses to see UV you are going to have to preserve the information of the direction of UV rays. Fluorescence will radiate it in all directions Graeme Bartlett (talk) 01:16, 11 June 2012 (UTC)[reply]

An Image intensifier is a vacuum tube device by which one may obtain an image in IR (infrared) light. DriveByWire (talk) 13:35, 11 June 2012 (UTC)[reply]

If you want to "see" UV you can get a CCD or other optical detector camera, remove the hot filter and replace the glass lens with a fused silica or fluorite lens. Then attach a 350nm UV pass filter. A normal camera glass lens is a bit opaque to UV. And air is opaque at the shorter wavelengths. Graeme Bartlett (talk) 11:08, 12 June 2012 (UTC)[reply]

Primary cortices of "other" senses?

If each sense has its own cortex (primary visual, primary auditory, etc.) what about the "others" such as equilibrioception, feeling the fullness of one's bladder, etc.? Is there such thing as the "primary equilibrioceptive cortex (EQ1)" ?

129.2.171.55 (talk) 21:40, 10 June 2012 (UTC)Nightvid[reply]

The vestibular cortex is the equilibrioceptive part -- not much is known about it, but it does seem to exist. I would expect that bladder fullness activates the somatosensory cortex, although I don't specifically know. Some other nonstandard senses, such as the systems that detect blood sugar levels or blood salt levels, activate parts of the insula. Looie496 (talk) 22:50, 10 June 2012 (UTC)[reply]