Wikipedia:Reference desk/Archives/Science/2010 January 18

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January 18

Cryogenic metal compared to traditional thermal energy storage

How do water-ice (e.g. http://ice-energy.com ), eutectic system, and molten salt forms of thermal energy storage compare to cryogenic thermos energy storage in metal, as a practical expected consumer rate premium for stored over demand electricity, approximately? 99.55.163.191 (talk) 01:09, 18 January 2010 (UTC)

You would have to assess how efficiently energy can be transferred in and out of your cryogenic storage. It is actually less efficient to cool than to heat, and in many cases heat is produced directly, for example of burning coal. It is then much more efficient to store the energy as heated materials. Then delay using the haat till later, for example to make steam for a turbine. Your water ice may be able to be harvested from nature, but cryogenic temperatures will not be found to exploit naturally on earth. Have a look at thermal mass latent heat molten salt energy storage cryogenics Graeme Bartlett (talk) 07:43, 18 January 2010 (UTC)

Are you saying refrigeration and cooling always produce waste heat? Why can't that waste heat be recovered and fed back into the cooling energy input? Is a steam turbine more efficient than a sterling engine? How much? Are thermal isolation losses greater at hot or cold extremes? 99.55.163.191 (talk) 21:59, 18 January 2010 (UTC)

Laws of thermodynamics. You can't beat the house, you can't break even, you can't get out of the game. If you've got a system that needs heating at some points and cooling at others, you can indeed combine these. To an extent. But you have to look at the actual temperatures involved to see how much this is possible, and it will never be 100% efficient: you will always have to use energy. And refrigeration by heat pump is very energy-expensive. Please read the articles linked by us and yourself: they're not perfect, but they have a lot of information and answer most of your questions in context. 86.179.150.200 (talk) 22:30, 18 January 2010 (UTC)

Thermodynamic cycles. You don't need to beat the house, you just need to lose less than if you were tearing the place up with non-renewables. Is the amount of work required and recoverable from taking a piece of metal in a thermos from 3 to 2 degrees Kelvin the same or less than the amount required and recoverable from taking the same metal from 2 to 1 degree Kelvin? 99.55.163.191 (talk) 23:42, 18 January 2010 (UTC)

While it's been a few years since I've studied thermo, however it appears you are trying to find the useful energy of one system and compare that to another. The best way to do that is through an exergy analysis of each system and comparing how much exergy is present in each. Wizard191 (talk) 13:05, 19 January 2010 (UTC)

Animals with colorful names (literally!)

I find these (common) names interesting for their extreme simplicity. So far I've got Bluebird, Blackbird, Brown Bear, Black Bear, and Bluefish & Redfish. Can anyone name some more in the awesomely simple pattern of (color)(animal type)? 218.25.32.210 (talk) 03:01, 18 January 2010 (UTC)

That's actually an enormous category. Humans are pretty lazy and uncreative about naming creatures. Just running down the List of hummingbirds, I see the Amethyst Woodstar, Berylline Hummingbird, Black Inca, Black Jacobin, Black Metaltail, Bronzy Hermit, Bronzy Inca, Cinnamon Hummingbird.... If you want two colours, you can have the Brown Violetear, Coppery Emerald, or Crimson Topaz. For a generic chioce, try the Colorful Puffleg. (Truth be told, I lost interest after I got to the letter C.) There are many, many more choices if you are willing to include colours describing body parts, as with Amethyst-throated Hummingbird or Azure-crowned Hummingbird.

Short of running through all of the subcategories in Category:Animals (and there are a lot of subcategories), I can't think of a good way to give you a comprehensive response — and there will be thousands of animals. TenOfAllTrades(talk) 03:31, 18 January 2010 (UTC)

OP here. Guess I wasn't explicit enough. I know the list will stretch into the thousands (millions?) if we allow for specific types of an animal. But I meant to restrict it to the overall categories. So your Amethyst Woodstar is excluded, as are essentially everything else you listed. Since you mentioned laziness, you might say I'm looking for the laziest of the lazy - names that end in general animal types: ____ bird, ____ dog, ____ fish, _____ turtle, _____ snake, etc. I think that narrows things considerably. 218.25.32.210 (talk) 04:43, 18 January 2010 (UTC)

Red Panda popped into my mind immediately. I don't see it listed yet. 75.152.185.94 (talk) 04:41, 18 January 2010 (UTC)

Green stink bug (Igny (talk) 04:47, 18 January 2010 (UTC))

Disqualified on account of the stink, but made me remember Red Bugs! 218.25.32.210 (talk) 05:05, 18 January 2010 (UTC)

But a stink bug is a type of animal. Rckrone (talk) 06:50, 18 January 2010 (UTC)

I'm a bit confused about what you mean. Why do you include dog, which at most refers to any member of the family Canidae while excluding Hummingbird which basically means any member of the family Trochilidae. Why do you exclude stink bugs, an even wider term then dog (or hummingbird), since it can refer to any member of the superfamily Pentatomoidea. Do you mean when the name can in some ways be further divided it is excluded? E.g. since hummingbird can be divided into humming and bird it's excluded?

This seems problematic to me. For example, do you exclude mongoose, even though a mongoose isn't even close to a type of goose, mon isn't a word and the etymology shows it didn't come from goose? Also even if so, why do you exclude black jacobin or black inca? True when you say jacobin and inca, most people are not going to think animal, but that's a rather fuzzy concept since many thing which people may associate with animals can have other meanings, seal for example; and some people are surely going to recognise that these terms can refers to animals.

And for example do you include panda, a term with no real biological meaning since it refers to two highly unrelated animals but not everything in between?

Do you only want cases when the etymology of the word shows it originated referring to an animal (and the other usages either derived from the animal or came up independently). If so, you'll likely need to do some analysis. For example, while it may seem likely inca and jacobin came from other words not referring to animals, I couldn't definitely find this is the case. Seal did originate referring to the animal as did mongoose. But does this mean you exclude rhinoceros [1] (also article) because the name originated from two words not meaning an animal "The word rhinoceros is derived through Latin from the Greek ῥῑνόκερως, which is composed of ῥῑνο-, ῥίς (rhino-, rhis), meaning nose, and κέρας (keras), meaning horn." (which happens for a lot of animals).

Also looking into into that got me thinking, do you include white rhinoceros even though the animal isn't even close to being white and the name may have originated from a corruption ofh a Dutch or Afrikaans word? And how about black rhinoceros, even though it too isn't black and the name was chosen to distinguis it from the white rhinoceros yet isn't even distinguishable by colour?

Nil Einne (talk) 10:42, 18 January 2010 (UTC)

White rhino's are the exact same color as black rhino's. The "White" part is a corruption of "Wide" (you have to say it with a South-African accent!) - and guess what? White rhino's have wider faces than Black rhinos. SteveBaker (talk) 20:28, 19 January 2010 (UTC)

Blue Crab! Green Crab! 218.25.32.210 (talk) 05:07, 18 January 2010 (UTC)

Golden Eagle, White Rhinoceros, Black Rhinoceros, Brown trout, Grey seal, gray heron, gray wolf, gray fox, red fox, yellow mongoose, brown hyena. Dragons flight (talk) 05:43, 18 January 2010 (UTC)

Brown kiwi perhaps. Nil Einne (talk) 11:09, 18 January 2010 (UTC)

Brown Snake, Blue ringed octopus (not lazy enough?) --220.101.28.25 (talk) 11:55, 18 January 2010 (UTC)

I would contest the OP's premise that redfish be included in this, as even a quick glance at the article reveals that there is no actual redfish, but rather that it's a common word used to refer to any number of species depending on the location of use. DRosenbach ^{(Talk | Contribs)} 15:19, 18 January 2010 (UTC)

That's why it's important to consult a reputable field guide. -- Coneslayer (talk) 15:34, 18 January 2010 (UTC)

Isn't that the ultimate in laziness? You can't even give it a unique name... In any case that also applies to black bear, bluebird and blackbird to some extent, it's not clear to me the OP wanted a name used to refer to a specific species only Nil Einne (talk) 15:40, 18 January 2010 (UTC)

Green Iguana, Black Widow Spider, Red Deer, Black-Tailed Deer, White-tailed Deer, Blue Whale Googlemeister (talk) 16:37, 18 January 2010 (UTC)

gun

when my granpa die he left me this gun http://en.wikipedia.org/wiki/Nambu_pistol is it safe to fire? i heard it can explode if fired —Preceding unsigned comment added by 67.246.254.35 (talk) 06:49, 18 January 2010 (UTC)

I see you're located in Fairport, New York. I suggest taking the pistol to a licensed gun dealer/retailer who can assess its current state and give you expert advice on its value, care, and maintenance. Without holding the item in our hands, we can only give information of limited usefulness in this case. Note that I am not familiar with New York firearm laws. It may or may not be legal to take that weapon to get it appraised without owning a carry-permit. Please consult with your local law enforcement office beforehand. 218.25.32.210 (talk) 07:01, 18 January 2010 (UTC)

i saw this vid of it being fired http://www.youtube.com/watch?v=EpZJ7FOQxyA it looks like it hurts your wrist to fire it why is that true if it a low cal gun —Preceding unsigned comment added by 67.246.254.35 (talk) 09:09, 18 January 2010 (UTC)

From that video alone, I can't see why you would be led to believe that it hurts your wrist. What I saw looks like the typical recoil that I'd expect from such a pistol. Note: I've never owned one of these but I have fired many pistols before. Dismas|^(talk) 10:20, 18 January 2010 (UTC)

i say that because it jerks yer hand to the side awkwardly while most guns go str8 back. this vid is a good example

http://www.youtube.com/watch?v=mDNqO4bCGXY

side by side comparison with a 45 this guy has more recoil and jerks yer hand to side

There are two red flags in our article: Firstly that the safety catch on these things is completely ineffective (yikes!) and second that it used a 'weak' charge in it's 8mm ammunition. Using modern 8mm ammo might well impose more of a strain than an already old and poorly constructed gun could withstand. So I'd certainly take it to a decent gun shop and have them look at it. Also, it's possible that this thing is actually somewhat valuable - (if it's actually a "Baby Nambu" then it almost certainly is a valuable piece) and in that case, you'd want advice on taking care of it just in case collectors have some obscure reason why they want these guns in not-recently-fired condition. Basically, there are enough unknowns here to strongly suggest getting some expert advice. SteveBaker (talk) 13:20, 18 January 2010 (UTC)

It's not a bad idea to contact your local law enforcement. Your county sheriff offers a firearm safety course. New York State has strict laws related to firearms, especially pistols. Our article, Gun laws in the United States (by state)#New York can give you a rough overview; it claims that New York is the strictest state in the country. Receiving a gift from a family member may still need to be registered as a transfer of ownership transaction. Your sheriff is the best person to answer that question. Nimur (talk) 18:55, 18 January 2010 (UTC)

TV shows where guns are appraised say DO NOT CLEAN THE GUN before having a potential buyer make an offer, because steel wool/sandpaper/wirebrush destroys the original factory finish or the "patina" an old gun acquires. Edison (talk) 20:00, 18 January 2010 (UTC)

can some 1 answer the op about the recoil? —Preceding unsigned comment added by Killspammers (talk • contribs) 14:25, 19 January 2010 (UTC)

I don't see any unusual looking recoil. Guns will twist when firing due to the rifling in the barrel and that pesky Newton guy. Pay attention to the warning about modern ammo. If this gun is meant to fire only light loads, you'll need to either find a source for the light loads, or load your own. Friday (talk) 18:57, 19 January 2010 (UTC)

Gaines Adams - latest enlarged heart... victim?

So I read the two main articles linked to enlarged heart and neither were very helpful in answering my primary question: how can a professional athlete who (theoretically) has the best medical staff around, and who has been examined numerous times at levels most regular people never are, have an unnoticed enlarged heart and then die from it?

Gaines Adams is the most recent example of top-level professional athletes quite literally dropping dead and the autopsy essentially being "I'll be damned, he had an enlarged heart." This dude went through all the rigors of the NFL Scouting Combine and Draft only ~3 years ago. How could that possibly have gone unnoticed? 218.25.32.210 (talk) 07:18, 18 January 2010 (UTC)

Probably a great many fit people die of undiagnosed heart problems. See Jim Fixx & James A. Corea. The fact that a person is otherwise very healthy may mask some health problems. Genetics has a lot to do with it, so living a healthy lifestyle may help, or it may not. We also need to wait for ALL test results to come in to be absolutely certain of his cause of death. NB The reference used[2] says he died of cardiac arrest, it does NOT say the arrest was caused by the enlargement.--220.101.28.25 (talk) 08:38, 18 January 2010 (UTC)

According to Athletic heart syndrome, there are no clear symptoms of the condtion, which would explain why it goes undiagnosed. Also, without passing judgement on any athlete in particular, some googling indicate that an enlarged heart could be a symptom of steroid use[3]. In such a case the role of the medical team becomes more complicated. —Preceding unsigned comment added by EverGreg (talk • contribs) 10:02, 18 January 2010 (UTC)

Yes, reports say Adams had an 'enlarged heart', but if that is muscular development due to exercise, ie. Left ventricular hypertrophy, it seems it is unlikely to have caused his death. Quoting Athletic heart syndrome; "this syndrome is believed to be a benign condition but may be hard to distinguish from other serious medical conditions." See also, Ventricular hypertrophy and Cardiomegaly, though it appears you may have already. The only way to be certain is to wait for an official coroners report to be completed.
The OP(Original Poster/ IP 218.25.32.210) asks "How could that [enlarged heart] possibly have gone unnoticed? It may have been noticed, and presumed to be the normal result of exercise, which it might well have been. We don't know yet.--220.101.28.25 (talk) 12:56, 18 January 2010 (UTC)

While it is true that he had an enlarged heart, the assumption that nobody ever noticed is not valid. It may very well have been known that he had an enlarged heart long before he joined the NFL. There are many people in the NFL with medical conditions, such as diabetes. -- kainaw™ 14:54, 18 January 2010 (UTC)

Kainaw is correct; you're going to have to document that the player didn't know; professional athletes, like test pilots, have a long history of concealing illnesses that might cause a doctor to veto their participation. Comet Tuttle (talk) 18:51, 18 January 2010 (UTC)

I dunno about posting links to SI as a reference source but they had an article about this that may be of intrest to you.[4]. 66.133.196.152 (talk) 13:09, 20 January 2010 (UTC)

It might be too late to join this discussion, but I can attest to the fact that it can actually be fairly difficult to diagnose an enlarged heart from a common chest echo, especially if you are viewing a dicom (or video) of the echo and not actually performing the test. CoolMike (talk) 23:33, 22 January 2010 (UTC)

Osteological signs of birth

In archaeology/osteology, is is supposedly possible to see if and how many times a women has given birth by observing the pelvic bone. If I remember correctly, each child leaves a small indentation in the bone. Is this true? What happens, physically, and why? How reliable is the technique for assessing number of children? Having just given birth to a child myself, I am very curious. (P.s. The osteology article is very brief, and I don't know where else to search for this information. Thank you for your help! D.s.) - Mommy —Preceding unsigned comment added by 90.233.22.17 (talk) 11:22, 18 January 2010 (UTC)

This question actually came up a while ago: [5] In short: The archeologists thought they could, but the marks could have other origins too, so now they'r not so sure. EverGreg (talk) 14:22, 18 January 2010 (UTC)

Thank you! Now I remember that I just recently read in a magazine of popular history about an Egyptian grave where the woman was determined not to ever have had children. Perhaps as suggested in nov 2008, NOT having ever been full term pregnant/given birth can more accurately be determined. For me, as for many, relaxin significantly affecting my pubic bone and lower back joints, and this could perhaps be possible to see as "scars" or changes on the bone. But it is just a speculation. - Mommy —Preceding unsigned comment added by 90.233.22.17 (talk) 14:43, 18 January 2010 (UTC)

Yup, determining that the woman never gave birth might be feasible, if the soft part of the skeleton is not eroded away. By the way, congratulations! :-) EverGreg (talk) 18:44, 18 January 2010 (UTC)

Name for a symptom

What is the name for a muscle spasm that only occurs when a muscle is in use? For example (and why I'm asking), I was watching a guy at a hotel yesterday who seemed normal until he walked. If he walked on flat ground, he was fine. When he had to step up with his left left, he was fine. When he stepped up with his right leg, his muscles would basically overshoot the target, sending he knee up above his waist. He appeared rather surprised by it every time it happened. I watched him go up the stairs and once in about 5 steps, his right leg would spasm upwards again - but only when he was stepping up with it. Therefore, I don't believe "spasm" is the correct term. -- kainaw™ 15:56, 18 January 2010 (UTC)

I believe that would be called a "focal dystonia". Looie496 (talk) 17:20, 18 January 2010 (UTC)

May also represent an intention tremor; or a loss of proprioception, as from a unilateral dorsal column infarct. Tuckerekcut (talk) 03:11, 19 January 2010 (UTC)

I have no means of knowing the guy's history or medical conditions to know why he had this symptom, but both focal dystonia and intention tremor seem like good descriptions of the symptom. After posing the question, I thought that he may have simply been a member of the The Ministry of Silly Walks. -- kainaw™ 07:24, 19 January 2010 (UTC)

Why is diamond metastable?

Solid-solid transitions are slow, but even phase transitions in crystal structure in say, various iron alloys, etc. are faster than diamond converting to graphite at 1 atm... John Riemann Soong (talk) 16:33, 18 January 2010 (UTC)

Is it the strength of a (nonpolarly unreactive) C-C covalent bond versus a more easily polarisable (and weaker) metallic bond? John Riemann Soong (talk) 16:40, 18 January 2010 (UTC)

Our article on Material properties of diamond says that their remarkable degree of metastability is due to a very high activation energy barrier that effectively prevents the transition under normal conditions. Mikenorton (talk) 20:19, 18 January 2010 (UTC)

Well yes, but that's the definition of metastability. What it doesn't tell me is what's so special about diamond versus say, metal, phosphorus or better yet, ionically-bonded compounds. John Riemann Soong (talk) 07:13, 19 January 2010 (UTC)

Well diamond being the hardest material at normal pressures shows that the bonds are very rigid and hard to change. Therefore hard also to change in the direction required for graphite. Also atoms have to move around. Graeme Bartlett (talk) 09:36, 20 January 2010 (UTC)

What is the molar vacancy function for diamond like? John Riemann Soong (talk) 05:37, 22 January 2010 (UTC)

texting

how does a company make it so if you text them it charges u ten bucks? how do they set that up? —Preceding unsigned comment added by Killspammers (talk • contribs) 16:47, 18 January 2010 (UTC)

If you're thinking about Haiti, I believe that's a special arrangement, but the ordinary way to charge a fee for a phone call is to use a 900 number. Looie496 (talk) 17:12, 18 January 2010 (UTC)

See short code. There's nothing special about the Haiti ones (except that some carriers are waiving fees and/or expediting payment of the proceeds). -- Coneslayer (talk) 17:15, 18 January 2010 (UTC)

It must be a standard option because there are things like joke lines where you text them and they send you back a joke every day (and charge you an outrageous amount for doing it while being very quiet about how you unsubscribe!) SteveBaker (talk) 01:16, 19 January 2010 (UTC)

Short Life of Light Bulbs

Light bulbs used in the fixture on the wall over our garage door burn out (by which I mean "stop working") far faster than bulbs used inside or in other outside fixtures. The difference is dramatic; months as compared to years.

I'm trying to figure out why this might be.

These are ordinary wire filament bulbs, inside a fixture where they are protected by a glass cover.

On the theory that the problem might be vibration I have tried bulbs intended for use where there is vibration, i.e., bulbs sold for use in sockets on electric garage door openers. There is not actually a lot of vibration as the garage door is not used.

I also tried bulbs intended for use in ovens and bulbs intended for "country service", i.e., with fluctuating voltage. All these bulb types went quickly.

Is there any possible peculiarity of a circuit that might explain this behaviour?

I realize I could switch to another type of bulb. Being stubborn and curious, I'm still trying to figure out why this is happening. Also I'm wondering if there is some type of quirk in the circuit that makes it dangerous in some way.

Thank you, Wanderer57 (talk) 16:49, 18 January 2010 (UTC)

Check for vibration and either get a non-filament bulb (there are many types of CFLs now) or get a bulb for a hand-carried light. They cost a lot more, but have a much stronger filament that handles the vibrations of carrying and bumping the bulb. I had this problem long ago when I lived on an air station. Regular bulbs couldn't handle the low flying jets. I got the more expensive bulbs and they never burned out. -- kainaw™ 18:57, 18 January 2010 (UTC)

Store near me has incandescents specifically labeled as "for garage-door openers" and says they are specially designed for high-vibration environments. DMacks (talk) 19:01, 18 January 2010 (UTC)

My vote would be thermal cycling. I bet the garage heats up and cools off to a much wider temperature range than the rest of the house. (The more important effect is probably due to the cold end, as the bulb heats up to incandescent temperatures whether indoors or outdoors). This would yield marginally more strain on the filament due to thermal expansion and contraction; it may be enough of an effect to decrease the lifetime of the bulb. Nimur (talk) 19:05, 18 January 2010 (UTC)

By the way, our thermal cycling article is pathologically bad... Nimur (talk) 19:12, 18 January 2010 (UTC)

Light bulbs filaments routinely and uneventfully rise a couple of thousand degrees C when they are switched on. A few degrees in the starting room temp, less than a 1% difference in the temperature rise, would be extremely unlikely to have a measurable effect on bulb life. Frequent switching on and off would be a more likely reason for a filament to fail. Edison (talk) 01:42, 19 January 2010 (UTC)

One test of this could be to leave the light on all the time, but this sounds like a rather expensive, slow, and unsatisfying test. Comet Tuttle (talk) 19:47, 18 January 2010 (UTC)

I am interested in the voltage supplied to the bulb, since a 10% increase in voltage above nominal decreases bulb life by half. Has the voltage supplied to the short-lived filament been checked? Do you ever notice kights getting dimmer or brighter when some large appliance turns on? Is the bulb on a motion detector which cycles it on and off frequently? Edison (talk) 19:57, 18 January 2010 (UTC)

But a heavy load would produce a decrease in voltage. (Ohm's Law, you know.) I can't think of any situation where an increase in voltage would be created by improper domestic wiring or too small a circuit. My vote goes with vibration from opening and closing the garage door. The lot that our house is built on is adjacent to a railway spur and we went through bulbs like crazy before we switched over to CF, presumably from the vibration due to the trains. Short Brigade Harvester Boris (talk) 20:04, 18 January 2010 (UTC)

If a neutral connection is loose, either at the breaker panel or at the transformer, with 120/240 three wire circuits (or their non-US equivalent) a loose neutral causes lights on the same side as the heavy load to get dim and those on the other side to get bright. In the worst case, the heavily loaded side would go to 0 volts and the other side would go to 240 volts (or higher in other countries). Edison (talk) 01:46, 19 January 2010 (UTC)

You might have been unlucky regarding the Bathtub curve of reliability engineering, where things like lightbulbs or humans tend to fail either at the beginning or at the end of their lives. And I understand that switching lightbulbs on or off shortens their lives. Does the outdoor light get turned on or off more than the others, such as by a motion detector? 92.24.114.231 (talk) 20:20, 18 January 2010 (UTC)

Thanks for these thought-provoking comments.

This fixture is more exposed to wind than the other outside fixtures. Thus in winter it must get somewhat colder than the others. It is on the south side and is the only one exposed to much direct sun so it must warm up a bit more on winter days.

It is usually only turned on and off 2 or 3 times a day, the same as the front door light which is on the same circuit. The front door bulbs are only replaced every few years.

There are no appliances that put a heavy drain on the power supply.

All the other outside fixtures are on brick walls. This one is on siding so it would get more wind-induced vibration.

I wonder if it is a combination of factors or just one of them. Wanderer57 (talk) 23:13, 18 January 2010 (UTC)

Antarctica again

The Antarctic plate movement is estimated at least 1 centimeter/per year towards the Atlantic Ocean., This seems to beconfusing sentece but I'm still confuse with what it meant by Antarctica is moving to the Atlantic. I can't move it to the west because the Americas is going to the west, does to the Atlantic at this case means moving to the east?--69.228.132.51 (talk) 19:00, 18 January 2010 (UTC)

(Antarctic Plate is the article.) Comet Tuttle (talk) 19:54, 18 January 2010 (UTC)

(ec)This relative motion is unreferenced. Our map of relative motion (File:Tectonic plates boundaries detailed-en.svg) suggest that the Antarctic plate is actually moving away from the Atlantic Ocean and towards the Pacific Ocean. N.B. All motions are compared to the African Plate, which is close to stationary. Mikenorton (talk) 19:59, 18 January 2010 (UTC)

Wait. What is N.B?--69.228.145.57 (talk) 00:31, 19 January 2010 (UTC)

Nota bene. Clarityfiend (talk) 00:40, 19 January 2010 (UTC)

Wait Mike, the map said 10-15 cm/year. Antartica is NOT stationary. Stationary on Wikitionary means not moving. Africa is moving to the northeast [6] at 2.15 cm/year. That is what Ruslik said.--69.228.145.57 (talk) 00:49, 19 January 2010 (UTC)

I did say that the African plate (not the Antarctic plate) is 'close to stationary', the African plate is often used as the reference for all plate motions but these are not absolute values, for that you need another reference frame. Mikenorton (talk) 19:26, 19 January 2010 (UTC)

Palezoic climates

and once again it is covered with trees, as it was 300 million years before This was said Antarctica was tree covering 300 million years ago, it was at the south pole though, was antarctica actually that green 300 million years ago when it was in the south pole? Not white with ice? Yea, things do become more and more fuzzy after Jurassic time.--69.228.132.51 (talk) 19:43, 18 January 2010 (UTC)

I'm no paleogeologist, but 300 Ma was right around the dividing line between the Carboniferous and Permian ages, and our Permo-Carboniferous article says it was "a period of great glaciation", with big ice sheets. Comet Tuttle (talk) 20:07, 18 January 2010 (UTC)

There is only ice at the poles during an ice age. (Technically speaking, we are currently in an ice age, just an interglacial period of one.) However, that said, 300 million years ago was in the middle of the Karoo Ice Age. That article says "The extent of glaciation in Antarctica is not exactly known, due to its present ice sheet." I don't think Antarctica was actually at the South Pole at that time - the supercontinent of Gondwana was centred on it and Antarctica was at the edge of Gondwana, so would have been a fair distance away from the pole. --Tango (talk) 20:13, 18 January 2010 (UTC)

This plate reconstruction for 306 Ma shows antarctica near the pole and being glaciated. Mikenorton (talk) 20:23, 18 January 2010 (UTC)

300 is wrong, but may just be a case of fuzzy numbers. There is evidence of extensive forests in the deep Antarctic (80 or 85 S) at 265 million or so. Dragons flight (talk) 20:17, 18 January 2010 (UTC)

Hang on! I've solved the problem. It doesn't says "300 million years ago", it says "300 million years before". That is, before 100 million years in the future (the article the OP is quoting is The Future Is Wild). That means it is talking about 200 million years ago. There weren't ice caps 200 million years ago and Antarctica would have been covered by trees. --Tango (talk) 21:40, 18 January 2010 (UTC)

periodic table question

Sodium has the chemical abbreviation Na. Our article says that stands for the Latin word Natrium, however, since it does not really exist in an elemental form in nature, how would the Romans have named an undiscovered element? Googlemeister (talk) 20:43, 18 January 2010 (UTC)

The history section of the sodium article explains what people in the more distant past (not Romans) were using and what they were calling it. It was a compound and not the pure element, obviously. They were obviously not filling out the periodic table when they picked names for chemicals around them. It was apparently not call Natrium until the 19th century, in any case. --Mr.98 (talk) 20:57, 18 January 2010 (UTC)

See also new Latin. (I added a link to it in the sodium article as well.) Rckrone (talk) 04:00, 19 January 2010 (UTC)

Efficiency of Einstein refrigerator

I saw it mentioned in the archives, but not the answer to this: What is the first-order efficiency (e.g., with no waste heat or waste cold reclamation in a practically insulated system) of the Einstein refrigerator? 99.55.163.191 (talk) 22:38, 18 January 2010 (UTC)

Running the Einstein refrigerator in reverse as a heat pump

Would it be possible to run it like that for home heating? And why are not heat pumps in general used more for heating? 89.240.50.241 (talk) 23:31, 18 January 2010 (UTC)

Heat pumps ARE used for heating all the time. Dauto (talk) 00:48, 19 January 2010 (UTC)

Where? When? How? 89.240.50.241 (talk) 00:53, 19 January 2010 (UTC)

I agree, I'd like to know that too. Pretty much every building I know of is heated by either electric resistance heaters or burning something (gas, oil, coal, wood, etc.). I can't think of a single building heated by a heat pump, despite our article saying they are up to 4 times more efficient. That seems strange to me... --Tango (talk) 00:57, 19 January 2010 (UTC)

For what it's worth, the newish Community Centre in Woolfardisworthy (aka Woolsery), Devon, England is heated partly by a ground-source heat pump. (It also generates electricity using solar cells and a wind turbine.) 87.81.230.195 (talk) 04:01, 19 January 2010 (UTC)

"Reverse cycle" air conditioners are quite common in Australia - possibly they go by a different name elsewhere. Mitch Ames (talk) 00:59, 19 January 2010 (UTC)

That article (which was a link to this section before you changed it and I edit conflicted with you) says they aren't designed to replace heaters (I'm not sure what they are designed to do...). --Tango (talk) 01:04, 19 January 2010 (UTC)

The section is actually a sub-section of Portable air conditioners, which is why I changed it. Fixed reverse-cycle units are common in Australia, but I haven't seen portables used for heating. The Air conditioner article doesn't otherwise mention "reverse-cycle" at all - but probably it should, even if it is only a reference to Air_conditioning#Heat_pumps. Mitch Ames (talk) 01:20, 19 January 2010 (UTC)

I've added Air_conditioner#Reverse-cycle, which is currently just a stub, containing an "expand section" template and "for details see Air conditioning#Heat pumps". Mitch Ames (talk) 07:57, 19 January 2010 (UTC)

My house has a heat pump - the house we had before this one had two of them (one for upstairs and one for down). It's basically just an airconditioner run backwards - you aircondition your back yard and dump the waste heat into the house. It has a resistive heater but that only turns on if you switch on the "Emergency heat" switch...which we basically never do. They are popular here in Texas because for most of the year you need cooling - not heating - so having a system that's optimised for cooling makes a lot of sense. I'd be surprised if they were 4x more efficient than a resistance heater. What losses are there in a resistive heater? SteveBaker (talk) 01:10, 19 January 2010 (UTC)

It's not that there are losses in a resistive heater (which might act at 100% efficiency) - it's that there are "gains" in a heat pump, which extracts heat from the outside air thus operate at greater than 100% efficiency (ie more heat energy added to the room than electrical energy consumed). Mitch Ames (talk) 01:23, 19 January 2010 (UTC)

Well, "efficient" is the wrong word, technically speaking. See Heat pump#Efficiency for details. --Tango (talk) 01:24, 19 January 2010 (UTC)

As I understand it, they're really only economical when the temperature doesn't get too cold outside (something to this effect was said in the heat pump article). Here in Minnesota, we had a guy advertising them to be used in the fall and spring, but when it gets really cold outside, it becomes cheaper to burn natural gas. Buddy431 (talk) 03:28, 19 January 2010 (UTC)

According to our article, heat pumps become no more efficient than electric resistor heaters at around -18°C outside temperature - that's on the cold side, even for Minnesota, but gas heating is usually more economical that electric heating, so your advertising guy is probably talking sense. --Tango (talk) 04:18, 19 January 2010 (UTC)

Heat pumps are (in principle) always more efficient than resistor heaters. It is true though that their efficiency goes down at lower temperatures and eventually a gas heater will be cheaper. Of course a heat pump that runs on gas instead of electricity would be even better. Dauto (talk) 05:14, 19 January 2010 (UTC)

It's a heat pump normally. It works by pumping the heat out of what you're cooling. 67.182.169.172 (talk) 06:16, 20 January 2010 (UTC)

Although in southern england the temperature is usually above freezing most of the winter, and hence would be suitable for heat pumps, I've never heard of anyone using them, and I've never seen them advertised. While people use gas whenever possible, many places do not have a gas supply. The alternative is oil - expensive in the UK - or night-storage electricity. So heat pumps could suit England, but they are never advertised. 92.29.57.199 (talk) 11:33, 20 January 2010 (UTC)

That's because heat pumps are expensive to start with - and they need regular maintenance. They are common here in Texas because having air conditioning in the long 100 degF plus summers is a virtual necessity - and a heat pump is just your standard air conditioner run backwards. (As I said - what the A/C does in winter is to air condition your back yard and dump the waste heat into your house...or if you prefer, you run your heat pump in the winter and in the summer, you heat your back yard using heat extracted from the air in your house!) Once you have air conditioning, the heat pump comes "for free" - and here in Texas, where the winters are mild, you don't want to go to the expense of having a fancy heating system that's only turned on for maybe a month or so each year. In the UK, the summers don't get hot enough for long enough to justify the expense and hassle of a home air conditioner - so heat pumps would represent an outrageous addition to the price of a new house. It's also very difficult to add air conditioning (and hence a heat pump) to a house that wasn't designed for that because there is no place for the air ducting. SteveBaker (talk) 14:27, 20 January 2010 (UTC)

I was wondering if the Einstein refridgerator could be run backwards as it has no moving parts and hence ought to be more reliable and not need maintenance. And its odd to think that something very similar to a fridge could be expensive. In the UK the super-efficient gas boilers that are required by law cost the equivalent of $3000 or so plus another $2000 for radiators, and require a lot of maintenance, while fridges need none. I imagine the price ought to be less for an air heat pump, as the complexity would less than that for the latest gas boilers. 92.29.57.199 (talk) 21:27, 20 January 2010 (UTC)