Wikipedia:Reference desk/Archives/Science/2010 April 16

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.

April 16

The mass of something 1836 times smaller than you?

An electron is only 1,1836 the mass of a proton. If your mass was 50 kilograms, what would be the mass of something 1836 times smaller than you? Try it the other way. What would be the mass of something 1836 times larger than you? —Preceding unsigned comment added by BlackBerryStromGuy (talk • contribs) 00:51, 16 April 2010 (UTC)

Not sure what you're asking here, but this appears to be simple arithmetic. If you weigh 50kg something that's 1836 times smaller than that weighs 50/1836 kg (about 27g or call it give or take 1Ounce. Something 1836 times 50kg is 50 * 1836 kg or about 90 tons. Call it about 19 elephants. Tonywalton ^Talk 01:07, 16 April 2010 (UTC)

This reads like a homework question, yet it makes no sense as a homework question to me. Why did you need to know this? Vimescarrot (talk) 10:44, 16 April 2010 (UTC)

Neutrons have slightly more mass than protons and I have plenty of them in me, how is it on your planet? Cuddlyable3 (talk) 12:33, 16 April 2010 (UTC)

I simplified the title for reference. Cuddlyable3 (talk) 19:30, 16 April 2010 (UTC)

I think the OP is asking for the name of an object that is either 1836 times smaller or larger in terms of mass than a 50-kg person. ~AH1^(TCU) 16:16, 17 April 2010 (UTC)

Internet searches for non-linear notations

Please see Wikipedia:Reference desk/Computing#Internet searches for non-linear notations. -- Wavelength (talk) 01:21, 16 April 2010 (UTC)

Icelandic volcano and air travel.

So - just how long could the volcano in iceland keep aircraft from flying over the UK? Some sources say that the wind could change direction - like that would solve the problem...but couldn't this think keep on belching dust for a very long time? Just how long could it keep going? Days? Weeks? Months? Years? SteveBaker (talk) 02:21, 16 April 2010 (UTC)

This article quotes a volcanologist at the University of Edinburgh as saying that the eruption could last years. As for disruption of air traffic, it will very much depend on the direction of the winds aloft. After British Airways Flight 9 and KLM Flight 867, the aviation industry is very concerned about flight though volcanic ash clouds. -- Flyguy649 ^talk 02:38, 16 April 2010 (UTC)

If it keeps going for years - the wind is going to cause this kind of chaos several times a month for all that time? That would be kinda annoying! SteveBaker (talk) 02:54, 16 April 2010 (UTC)

Yup. Rio de Janiero might become a big hub for Europe-North America air traffic! -- Flyguy649 ^talk 02:56, 16 April 2010 (UTC)

And US-Europe cruiseships may see a revival. caknuck _° needs to be running more often 06:21, 16 April 2010 (UTC)

(Western/Nothern) Europe is perhaps somewhat fortunate that they have decent high speed rail for intra Europe travel which may get a further boost if this disruption continues. BTW, [1] suggests that repeated disruptions are definitely possible. Incidentally, as someone who just purchased something from Germany and paid a lot for shipping to because of $#(*&%!* Deutsche Post/DHL's we don't price by weight for packets policy the disruption is rather annoying. Nil Einne (talk) 07:23, 16 April 2010 (UTC)

Ironically I just realised the German airspace wasn't closed at the time I wrote my message above although it is now. Of course since the packet was only sent on Friday it probably will still be in the system in Germany somewhere and may not have really been affected yet. Nil Einne (talk) 15:53, 17 April 2010 (UTC)

Epic: "Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped." --Sean 16:52, 16 April 2010 (UTC)

Cool animation of the ash plume from the ESA. -- Flyguy649 ^talk 09:52, 16 April 2010 (UTC) We can survive cancelled commercial flights for a while but there are other emergency aviation needs such as air ambulances, mountain rescue and forest firefighting. Would a battery powered electric helicopter be a feasible solution at this time? Cuddlyable3 (talk) 12:27, 16 April 2010 (UTC)

Battery powered helicopters can barely support their own weight. But you could use a helicopter with internal combustion and a filter (like a car engine basically), instead of a jet engine or turbine. And I think most non-military helicopters are internal combustion. Also, fly low, under the plume. Ariel. (talk) 12:51, 16 April 2010 (UTC)

Au contraire. See the "Hexacopter," which can carry itself plus a substantial payload. Would the size/mass problem that defeated Langley prevent its being scaled up? Edison (talk) 20:09, 16 April 2010 (UTC)

It weighs 1.2Kg, and can carry 1Kg, with a flight time of a couple of minutes. 36 minutes with no payload. In contrast a typical gas powered helicopter also has a payload of about it's own weight - but it can do it for hours. Ariel. (talk) 01:49, 18 April 2010 (UTC)

Because the eruption was largely unexpected, the safest course of action in the short-term was to simply cancel all flights in affected areas and put up with the inconvenience and economic losses. If the hazardous conditions exist for a few more days, flight plans will be developed to avoid the affected areas. If conditions last for a few more weeks, safety assessments will take place and flight procedures will be developed that fly in the affected areas but minimize the risk. If the hazardous conditions really do last "several years", then we will have time to develop engineering fixes to the flight control electronics, engine intakes, and so on, to accomodate the non-ideal conditions and safely fly through zones with large amounts of volcanic ash. This is really a matter of estimating how much effort should go into developing solutions for a problem which might be temporary anyway. If global dispersion of volcanic ash becomes the most serious impediment to air travel over the next several decades, we will see engineers developing revolutionary new kinds of aircraft that are impervious to ash plumes - but that would only be worthwhile if the consequences of volcanic eruptions are huge. Nimur (talk) 15:35, 16 April 2010 (UTC)

Engineering fixes seem difficult at best. Aircraft that have flown through ash plumes in the past had all of the paint scoured off the plane and the windows 'sandblasted' to the point where it was impossible to see out! The very nature of jet engines is that:

• They take in a lot of air at high speeds...filtering that air is not a possibility.
• They burn fuel at temperatures high enough to melt the tiny rock fragments in the ash and turn it into the sticky glassy substance that then coats the internal parts.
• That the fuel burns at a temperature that's high enough to melt the engine parts themselves if there isn't a cooling airflow ducted in through narrow holes that get blocked by the ash.

It's not going to be easy (and perhaps not even possible) to fix those things. SteveBaker (talk) 18:14, 16 April 2010 (UTC)

Rocket planes wouldn't suffer those engine problems, because they have no air intake. Abrasion could be a problem, but I feel confident that it could be solved. SpaceShipTwo is already well into the design phase - this is not an impossible idea! But these rocket-powered aircraft are not cost-competitve with conventional aircraft - so rocket planes could only become mainstream if conventional aircraft become totally inoperable over a long enough period of time to affect airline company technology strategies. Nimur (talk) 14:37, 18 April 2010 (UTC)

Why couldn't air routes be lowered to fly under the plume? (High mountain areas excepted). Certainly it would be louder for those on the ground. How much would fuel consumption go up at say 10,000 feet (3000 meters) rather than 30,000 feet (9100 meters) or whatever is the favorite altitude for passenger jets? Edison (talk) 20:11, 16 April 2010 (UTC)

Because a) debris is constantly precipitating out of the debris cloud and b) this would require constant monitoring of the ash cloud ceiling (which can vary greatly locally) over an area of tens of thousands km². Better to go around than under. caknuck _° needs to be running more often 22:16, 16 April 2010 (UTC)

After the eruption of Krakatoa, there were no airplane flights for 20 years!! Edison (talk) 03:57, 17 April 2010 (UTC)

Soviet historians strongly disagree! Nimur (talk) 18:04, 18 April 2010 (UTC)

As the eruption continues, the ash plume could drift west over the North Atlantic, cooling the region and possibly setting off the negative phase of the Atlantic Multidecadal Oscillation. Any long-term effects on climate are expected to be slight, but the eruption contains both SO₂, which could cool the ash-affected regions of Western Europe while increasing severe weather in the region and producing acid rain, as well as water vapor which would produce a net contribution to the warming of the globe as it is emitted into the stratosphere where it has the biggest effect. Also, the volcano is likely to trigger a second eruption at Katla, which would prolong the ash plume even further and melt more of the glacier in Iceland which would melt into the sea, flooding more villages and having a slight effect on global current sea level rise. ~AH1^(TCU) 16:09, 17 April 2010 (UTC)

Our article says no long term climate effects are expected yet but they could still occur. Nil Einne (talk) 19:22, 17 April 2010 (UTC)

Some interesting facts from our article talk page.

1) It seems it isn't true all aeroplanes are grounded. Rather only IFR are forbidden. Many places still allow VFR. Of course all commercial flights and large planes use IFR so they're all affected. And VFR implies you have to stay fairly low and have to be able to actually see where the aircraft is going so if the situation is so bad you can't see, you can't fly VFR.

2) One Russian plane did try this 'fly low' thing. However it's not clear how well planned this was since they ran out of fuel and had to divert to Vienna (original destination had been Rimini, Italy). In any case, even though they are supposed to have flown below the ash cloud, there are still calls for very rigorous inspection of the plane.

Nil Einne (talk) 19:22, 17 April 2010 (UTC)

Why not use piston engine powered propellor planes? Count Iblis (talk) 02:22, 18 April 2010 (UTC)

Black lights, wattage, and wave lengths

I have some glow in the dark powder pigment, specifically this that I use sometimes, and have been using a 75 watt GE black light bulb to charge it. I also have a 3W led UV light. The led operates at 395-400 nm wavelength, I think the 75W is at 365. Any ideas about the differences is the effectiveness of charging the powder? Using the flashlight is vastly preferable but not at a huge sacrifice to a brightness from the powder. Beach drifter (talk) 03:20, 16 April 2010 (UTC)

You need a certain wavelength to charge it. A longer wavelength will not charge it at all, and a shorter one just wastes energy. Once you have that wavelength, the brighter the light the faster it will charge (more or less). To find out how bright the bulb is, in theory you want the lumen or candela, but those are adjusted to human vision, and UV does not rate. Electrical watts tells you very little since you don't know how efficient the bulb is (unless they are both the same type, you did not specify). Confusingly, Radiant flux is also measured in watts. So are those electrical (input) watts or radiant (output) watts? Note: the powder could be a mix, and might have multiple desired wavelengths, but I think pure green isn't a mix. Ariel. (talk) 04:01, 16 April 2010 (UTC)

I'm fairly certain the powder is not a mix, it is very strong, pretty awesome stuff. The 75W bulb is an incandescent type that you can get at Walmart. The down side is that it gets very very hot and when camping requires a dc to ac converter and a car. Beach drifter (talk) 04:12, 16 April 2010 (UTC)

I think that Incandescent UV bulbs are ordinary bulbs with filters that remove visible light. The UV efficiency is probably horrible (but I don't have numbers). So despite being 75 watts little UV is made. But probably more than 3 watts worth. Can you do a test, just because I'm curious? Try to charge the powder with a regular 75 watt bulb. Anyway, what I would suggest for you is a 12 volt portable fluorescent lamp with a built in battery. Car mechanics use them, so it should not be hard to find. Ariel. (talk) 21:32, 16 April 2010 (UTC)

Palatine uvula

I read the article on this but didn't find the answer I was looking for. My query is: other than humans, do other animals have a uvula? If so, what it it used for since humans use it for language? —Preceding unsigned comment added by 99.250.117.26 (talk) 04:21, 16 April 2010 (UTC)

It is adapted by humans for use in language. Its other purpose is to close off the nasal sinuses from the throat, to prevent food from getting into your sinuses when you swallow. See also Epiglottis for a similar flap covering the trachea. --Jayron32 04:29, 16 April 2010 (UTC)

How does the uvula, which exists in the oropharynx, prevent food from getting into the sinuses, which communicate with the nasal antrum? DRosenbach ^{(Talk | Contribs)} 05:02, 16 April 2010 (UTC)

Look at the pictures in either of the two articles you linked. There are two flaps at the top and bottom of the pharynx. The top is the uvula and the bottom is the epiglottis. During swallowing, both flaps are pushed away, blocking the relevent openings to either end of the breathing system. --Jayron32 05:21, 16 April 2010 (UTC)

Both pictures are midsagittal planes, rendering 2D images of 3D objects. DRosenbach ^{(Talk | Contribs)} 18:56, 16 April 2010 (UTC)

My original question does not seem to be answered: do other animals have a palatine uvula? If they do, then I assume that it has the same function of closing off the nasal passage during swallowing since no other animal seems to have the same sophisticated vocal language that we humans do. —Preceding unsigned comment added by 69.77.185.91 (talk) 16:57, 16 April 2010 (UTC)

Do plants need to sleep?

Is it healthy for plants to be out in the sunlight all day and then under a fluorescent light at night? Should they be left in the dark to sleep? Do they need to sleep? Specifically I was wondering about very young pumpkin plants. For the hell of it, I just started a couple plants in pots [soup tins].--Brianann MacAmhlaidh (talk) 06:49, 16 April 2010 (UTC)

From what I read after a google search it seems that the leaves will grow OK, but the constant light will mess with flower budding, and other plant stages. So you might get a big plant, but no pumpkins. You might be able to start with constant light and grow them fast, then switch to a normal pattern when it's time for flowers, but I'm not sure. In general plants use the ratio of dark to light to know what season it is, and they do different things at various points in the seasons. Ariel. (talk) 08:28, 16 April 2010 (UTC)

It depends on what type of photoperiodism your plant exhibits. Pumpkins are in the same family (taxonomy) as cucumbers, which according to our article are day-neutral i.e. they will flower in any light regime. I don't know whether this carries over to to pumpkins, or whether other physiological processes will be affected by constant light. 131.111.185.69 (talk) 09:26, 16 April 2010 (UTC)

Thanks for the replies Ariel and 131.111.185.69. I've searched about on Google for this, though it seems like no one really knows for sure. Pumpkins aren't really the type of plant people plant indoors, I guess. Hopefully they'll be in the ground by the time they start flowering.--Brianann MacAmhlaidh (talk) 06:13, 18 April 2010 (UTC)

Refractive index less than one

In Refractive index it says: "Contrary to a widespread misconception, n may be less than 1, for example for X-rays." But doesn't that imply a speed of light greater than c? The only thing I could think of is that for X-rays this is "n" as compared to air, not vacuum. Ariel. (talk) 08:20, 16 April 2010 (UTC)

The phase speed is greater than c, but that doesn't mean that a signal can be sent with such speeds. Remember that an idealized monochromatic wave actually extends to infinity (only then the Fourier transformation yields a single frequency). The propagation of a wave packet will be slower. Icek (talk) 11:02, 16 April 2010 (UTC)

To be more specific, the speed of light in a medium is actually given by

$v_{g}={\frac {c}{n-\lambda {\frac {dn}{d\lambda }}}}$

which will always be smaller than (or equal to) c even when n<1. Dauto (talk) 15:12, 16 April 2010 (UTC)

This is the only known example of "real" faster than c propagation of light. Count Iblis (talk) 20:58, 18 April 2010 (UTC)

The Leaning Brown Building of the Spanish Steps

Photo A

Photo B

In Photo A, the brown building on the left seems to be standing perpendicular to the ground, as you’d expect.

But in Photo B it’s very different. Obviously it’s a function of where the photographer was standing and the direction the camera was pointing. The vanishing point seems to be a foot above the picture, yet the camera was clearly not aimed at the vanishing point. How to explain the effect? -- Jack of Oz ... speak! ... 10:48, 16 April 2010 (UTC)

Perspective distortion (photography)? It looks in the second camera as if the person is tilting the camera up slightly (unless that's just my eyes) which can have the affect of making buildings lean/slope in funny directions. 194.221.133.226 (talk) 11:11, 16 April 2010 (UTC)

The metadata for the left photograph indicates it has been treated in Corel Paint Shop Pro where it could have received perspective correction to make the vertical edges of buildings parallel. Cuddlyable3 (talk) 12:09, 16 April 2010 (UTC)

Looks to me like the photographer was tilting the camera up in the second picture. The fountain in the foreground also looks wrong. Take a look also at a tilt shift lens. Ariel. (talk) 12:30, 16 April 2010 (UTC)

The second image was shot up the hill without perspective correction, either with a tilt-shift lens or via software. Since there's an angle upwards, the vertical lines will converge in accordance with the principals of perspective. Our brain tends to edit out such vertical perspective, but not horizontal perspective, which we expect as a natural phenomenon. Therefore, pictures that exhibit vertical perspective look odd. It's the bane of architectural photographers, since most buildings are taller than the photographer, so shooting up, if one is reasonably close, is inevitable. I routinely correct for vertical perspective in Photoshop, since I haven't brought myself to spend on a nice T-S lens. The Spanish Steps are on a steep hill, so the vantage point of the first image, off to the side, avoids the problem to some degree (anmd appears to have been further fixed in Corel), while the second is significantly lower than the base of the steps. Acroterion _(talk) 17:21, 16 April 2010 (UTC)

Thank you, Acroterion, that was a very clear explanation. -- Jack of Oz ... speak! ... 03:41, 18 April 2010 (UTC)

For answering questions like this, you may want to post a link from the Featured Pictures talk page. Those guys are experts at correcting and understanding all kinds of distortion effects. 64.235.97.146 (talk) 18:19, 16 April 2010 (UTC)

brain activity and dreams

Every action of ours is ordered by our brain. In dreams, if we do any action like eating, fighting etc., it is because of the brain's activity or our obeying the brain's order, of course mentally. In that case, why is the body in reality not obeying the order of the brain (i.e. why don't we eat or fight, waking up from sleep, as a result of the 'order' from our brain) ? And if it does, like in case of somnambulism or something like that, we call it a 'disorder'. Another question is that why don't most of us remember the dream that we dreamt that particular night, at once after waking up. (i would rather prefer to be a fool asking questions that are foolish) —Preceding unsigned comment added by 125.21.50.214 (talk) 11:16, 16 April 2010 (UTC)

I'm not an expert here, but I know there are different segments of the brain. One bit is controlled consciously, another is automatic. Dreams are a result of, I suppose, random thoughts being viewed. Most people do remember their dreams, but stress and other factors can cause us to forget. If we disobey the orders of the brain, we get tired, hungry, or injured. That's all I can help you with. Maybe there are some experts here. 2D Backfire Master ^{sweet emotion} 11:21, 16 April 2010 (UTC)

Sleep paralysis. During sleep the body "switches off" the nerves that would otherwise carry out the actions. If they don't switch off, then you have Sleep walking. And sometimes it will stay switched off for short time after waking, which is quite terrifying when it happens. (It's happened to me twice.) Ariel. (talk) 11:38, 16 April 2010 (UTC)

Wow, that sleep paralysis article is awful. I think it's talking about 2 different things and doesn't even know it. Comet Tuttle (talk) 20:43, 16 April 2010 (UTC)

Yeah, as the sleep paralysis article explains (although not very clearly), there is a special circuit in the brainstem that disconnects the upper brain from the lower motor centers during the dreaming state. In experiments using cats where this small brain area was damaged, the cats would physically enact their dreams. There is a caveat though: sleepwalking is actually a different phenomenon. The data is limited, but it looks like a sleepwalking person is not actually in the dreamlike state, but rather in a state where part of the brain is asleep while other parts are awake. Looie496 (talk) 17:45, 16 April 2010 (UTC)

Michel Jouvet is famous for his experiments in which he destroyed a portion of the lower brain stem in cats that caused paralysis during sleep; some cats then could be seen to act out their dreams. Until, presumably, they were woken up by all the tactile input of walking around. A quibble with your first statement: Not every action of yours is ordered by your brain. Healing, most (or all?) of the digestion process, and several kinds of reflexes are examples. Comet Tuttle (talk) 20:43, 16 April 2010 (UTC)

However, when people are only half-asleep sometimes they will be woken up by a mini "spasm" that coincides with the partially awake dream of the person falling, and some scientists link this to the ancestral fear of falling out of a tree while sleeping. Do we have an article on this? ~AH1^(TCU) 15:56, 17 April 2010 (UTC)

Yes, see hypnic jerk. Looie496 (talk) 17:00, 17 April 2010 (UTC)

Why can't plants move?

What in evolution made plants immovable? They prepare their own food but is it 'food' all they need? They depend on wind, insects, water etc., for pollination, they would have been lot more better (than the highly-evolved humans) had they been able to move since the time of evolution. - Anandh, Chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 12:07, 16 April 2010 (UTC)

How could they both move and have roots? I think once they have roots, they are committed to it. If you mean move branches, some plants do, but most of the time it's not very useful for a plant to be able to do that. Ariel. (talk) 12:14, 16 April 2010 (UTC)

Some plants are capable of rapid movement. See venus flytrap. As an aside, movement takes a LOT of energy, so there needs to be a really good reason to evolve such a capability. In the case of the venus flytrap, it lives in such poor soil it needs to catch bugs for nutrients. --Jayron32 12:41, 16 April 2010 (UTC)

See Rapid plant movement for a lengthier list. Gabbe (talk) 13:04, 16 April 2010 (UTC)

It is also important to think of plant movement speed based on plant lifespan. Consider a plant that can live for 1,000 years. If it moves a branch a couple feet in a year, that is relatively fast movement/lifespan compared to animals. Another way to think about it: Animals have a very short lifespan compared to plants. So, they have to quickly find food. Plants have time to wait for food. -- kainaw™ 12:46, 16 April 2010 (UTC)

Not really. Even if you assume a human is only going to move 50 years, he would only be able to move 20 yards a year, and that is incredibly slow. I bet even a snail could beat that in a week or two. Googlemeister (talk) 13:41, 16 April 2010 (UTC)

One might as well ask why humans can't generate their own food by just sitting in the sun, as that would clearly be a lot easier than running around and trying to brain other creatures with stones. --Mr.98 (talk) 12:48, 16 April 2010 (UTC)

See tumbleweed, sargassum and phytoplankton.--12:56, 16 April 2010 (UTC)

Photosynthesis doesn't really generate enough energy to move around like us animals do. If plants wanted to move and dance under their own power they'd need to find a new source of energy.

The Venus Fly Trap mentioned above can take hours or even days to "reset" its traps. APL (talk) 14:51, 16 April 2010 (UTC)

Who says that having movment means something is higher evolved? If you ask me, plants were here before humans and have evolved to make their own food, be self sefficient during a regular life cycle and reproduce by using the natural occurences of the Earth. If you ask me, they are much higher evolved. 74.218.50.226 (talk) 15:44, 16 April 2010 (UTC)

That debate came up while back when the DNA of rice was completely sequenced. Previously, there was an assumption that dna sequence length equated to level of evolution. However, rice sequence length is much longer than human sequence length. So, I saw some people assume that the rice sequencing was wrong and they wanted to resequence it to see if was actually much shorted. Others assumed human sequencing was wrong and wanted to resequence it to make it longer. Some assumed that equating evolution level to sequence length was hogwash and dropped that whole idea. A few wacky scientists said that it was all correct and that rice was more evolved than humans. As one put it: Try living all year standing knee-deep in a cold bog and see how long you survive. -- kainaw™ 15:49, 16 April 2010 (UTC)

The first plants to appear were algae. They floated in the sea, carried by currents, getting nutrients from the surrounding water and using sun energy from the sun. They were no animals yet, so they couldn't feed from them. There was no oxygen in the atmosphere yet, so they couldn't use it to make the energy transformation that us animals use now. Time passed, and algae filled the oceans and increased the oxygen content in the atmosphere. Some of the oxygen dissolved in the sea water. Now some pluricelled (is that the name in english?) livings discovered a mean to eat the algae and use the oxygen to process its components into lots of energy. Algae couldn't have discovered that process because the ingredients weren't there when they first appeared. All plants descend from those algae, and all animals descend from those algae-eaters. Our ancestors went down that path of evolution and we are pretty much stuck into it, for good or for bad. There are some very successful species that decided to test new grounds (like fish becoming amphibian when they first went to land, and later some big land animals deciding to return to the sea and becoming whales) but they still carry an awful lot of inherit traits, and they needed a lot of generations and ambient influences to change their shapes. --Enric Naval (talk) 16:50, 16 April 2010 (UTC)

Multicellular? Zain Ebrahim (talk) 17:00, 16 April 2010 (UTC)

In English, we call it a multi-celled plant or animal. StuRat (talk) 17:02, 16 April 2010 (UTC)

Mimosa (the plant, not the drink) is quite fast moving, but does not do so to eat flies like the Venus Flytrap. Edison (talk) 04:28, 17 April 2010 (UTC)

Just be grateful that they can't move. Mitch Ames (talk) 08:19, 17 April 2010 (UTC)

Because they grow places instead of going places. Why waste loads of energy moving (and making your muscles warm to do so) when you can just sit still? Also plants move their chloroplasts around their cells in response to varying light using the same proteins (actin and myosin) that are in our muscles. With regards as to which are more evolved, I like to think that plants make things (a huge variety of secondary metabolites) whereas animals break things. The idea of linear evolution is stupid, everything is adapted to the environment it lives in and the lifestyle is uses. 131.111.30.21 (talk) 10:45, 17 April 2010 (UTC)

Incidentally, remember that many animals are sessile too. --ColinFine (talk) 14:15, 17 April 2010 (UTC)

Some plants use forms of vegetative reproduction that enable them to "move" over time along their roots to create other members of the same organism, see quaking aspen. ~AH1^(TCU) 15:53, 17 April 2010 (UTC)

Just consider the word 'plant'. Something that's planted doesn't move without intervention. Vranak (talk) 22:17, 17 April 2010 (UTC)

Mind controlling gene function.

A person's character is based on genes (excluding environmental factors)(they say...like father/mother is the son/daughter)but character changes as years pass by. Does that mean the gene expression or gene function for the 'disappearing character' lost/stopped? If so, can one's mind control the gene expression so that it would be advantageous for one to evade baldness, fear etc., by controlling the baldness/fear gene's expression/function ? - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 12:26, 16 April 2010 (UTC)

Are you sure "A person's character is based on genes" is true? It's probably affected to some degree by it, but not controlled absolutely. This is a very very old argument, with no single answer, but you can read all about it in Nature vs. Nurture. Ariel. (talk) 12:32, 16 April 2010 (UTC)

Yes, son/daughter has father/mother's character. The reason obviously is through inheritance (genes of course). It hence means genes control characters, though not absolutely as mentioned by Mr. Ariel. - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 12:54, 16 April 2010 (UTC)

How can you be certain that sons & daughters don't have their mothers/father's character because they were raised by their mother/father and so learned that personality. What percentage of their character is because they have their parent's genes, and what percentage is because they were raised by their parents? --Jayron32 13:55, 16 April 2010 (UTC)

Agreed. Genes are a minor factor, with environment being the major factor, and there's also a small random element (we know this since identical twins raised together aren't quite identical in personality). Now, as for the genetic part, yes, they can express at different ages. For example, sexual orientation may not express until puberty or even later. However, this certainly doesn't mean that this gene expression can be controlled by conscious thought. StuRat (talk) 16:56, 16 April 2010 (UTC)

"son/daughter has father/mother's character". This proposition implies that all siblings have the same character. That's certainly not true in my experience, and in the US we have somewhat of a tradition of presidents with ne'er-do-well relatives. --Sean 17:06, 16 April 2010 (UTC)

When you talk about the mind controlling gene expression, you are improperly mixing levels in a way that can only lead to confusion. There are many factors that influence gene expression, including levels of stress-related hormones such as cortisol. Since stress is clearly a function of cognitive factors, there must be at least some degree of influence of cognitive factors on gene expression. It is important to point out, though, that a gene that is not expressed does not disappear -- it is still there, and will still be inherited. Also gene expression often differs greatly for different cells within a single body. Looie496 (talk) 17:36, 16 April 2010 (UTC)

Stephen Pinker has argued that behavioral studies tend to underplay the role that genetics has on behavior. Studies that show, for example, that reading to your children before bed boosts their scholastic aptitude don't control for genetics so it could simply be the case that families with genes that lend themselves to scholastic aptitude include the tendency to read to children at night.

Even if one's DNA has a stronger influence on behavior than we normally assume, it doesn't necessarily mean that it's particularly strong (especially when we have very strong environmental factors). In this TED talk, Jonathan Haidt talks about a postulated innate morality but, as he argues, innate doesn't mean fixed. It's just means that there's an existing template that our genes provide that experience then revises. This is also part of Derek Bickerton's language bioprogram theory regarding innate grammar. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 19:31, 16 April 2010 (UTC)

Genes have essentially no impact on your character. They might on your intelligence etc, but a son of two really popular and charismatic people might be a real loner who is afriad of social interaction simply due to the fact that he's never learned how to act appropriately in social situations (I know a guy like this with parents like that). Also twin studies are rubbish, the twins do not go through identicle upbringings. It would be exceptionally naive to assume they do. Siblings, twins, often have different interests and do loads of different things. One twin might be a great footballer and become a PE/Gym teacher. The other may be more academically orientated and go on to be some brilliant proffessor.--92.251.148.126 (talk) 22:50, 16 April 2010 (UTC)

Genes definitely have some sort of impact on temperament. The correlation is too strong not to notice. But they don't determine it. John Riemann Soong (talk) 02:54, 17 April 2010 (UTC)

There are loads of anecdotes of twins separated at birth who reunite to discover they have many many common characteristics. I recall one example where a pair reunited after living in different states for several decades to find that the only real [readily describable in a Readers Digest article] difference between their personalities was their favorite sports teams. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 19:14, 17 April 2010 (UTC)

Map of the world folded along the equator

Where could I find a map of the world where the southern and northern hemispheres are superimposed, so that the same latitude north and south of the equator is shown in the same place? This results friom a discussion on the Entertainment Desk about how far south Australia is compared to how far north Europe is. Thanks 78.151.110.54 (talk) 16:33, 16 April 2010 (UTC)

There's a couple in our antipodes article. See also www.antipodemap.com --Shantavira|^{feed me} 16:46, 16 April 2010 (UTC)

Let's split...

Which came first, the split between plants and animals or the split between single-celled and multi-celled ? Since we have all 4 combinations, that implies that one of those splits happened twice. Here is are some possibilities I see:

SP = Single celled Plants
MP = Multi-celled Plants 
SA = Single celled Animals 
MA = Multi-celled Animals

SP -> MP -> MA -> SA

MP                
^              
|
SP -> SA -> MA

StuRat (talk) 17:14, 16 April 2010 (UTC)

I think Multicelularity evolved more than once but I don't think SP -> SA makes any sense. Dauto (talk) 18:23, 16 April 2010 (UTC)

So then do you think that single-celled animals (de)evolved from multi-celled animals ? StuRat (talk) 19:24, 16 April 2010 (UTC)

More relevant, I think, is the monophyly of Eukariotic life. Having organelles within your cell structure isn't necessarily a prerequisite to multicellularity, but it certainly helps. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 19:22, 16 April 2010 (UTC)

According to newer research in the last decade, the presence of multicellular life is most likely directly dependent on organelles, with the mitochondria possibly allowing for the evolution of multicellular life. Sjschen (talk) 14:42, 19 April 2010 (UTC)

It is not as simple as that. The chloroplasts found in plants are believed to come from unicallular organisms that became part of plant cells during their evolution. And there are things that are neither animals nor plants. I take it that the OP did not study biology at school. 78.151.110.54 (talk) 19:26, 16 April 2010 (UTC)

"Which came first" is hard to answer, because it depends on how you define "plant", "animal", and "multi-cellular". Is a plant "something that obtains energy from non-living sources", or "something that obtains energy from the Sun"? Is an animal "something that obtains energy from its surroundings", or "something that obtains energy from other living things"? Is a multicellular being any grouping of attached cells, only those groupings where the cells interact, or is it further restricted to ones with some degree of specialization of the cells? What does a mat of chemosynthetic bacteria count as? --Carnildo (talk) 22:39, 16 April 2010 (UTC)

I'm not sure a mat of bacteria should count under the term multicellular...if that were the case the layer of slime in bathtub would be considered multicellular life. The term multicellular life to me should only apply to colonies of cells with tight collaboration and specialization of functions, including that of various somatic and sexual function. These cell colonies cannot be chopped up and still be considered an organism. For instance, if you divide up a bacterial mat, it becomes several segments of viable bacterial mat, but if you chop up a C. elegans it will not be a viable organism (it can grow back its parts but each divided part is no longer a whole organism). Slime molds are harder to pigeon hole, but since their cells collaborate so closely in reproduction, I would put them in as multicellular. Sjschen (talk) 14:42, 19 April 2010 (UTC)

Reading articles like prokaryote suggests that things can be both single- and multicelled, and that things did not simply split but there was a network of splittings and mergeings, and that no-one really knows which came first. 78.146.229.142 (talk) 12:16, 17 April 2010 (UTC)

Multicellular life most likely arose after the acquisition of mitochondria or chloroplasts with animals containing the former and plants containing both. If you use this definition than the first single cell eukaryotes are animals (SA) since acquisition of the mitochondrias is the first step to increasing energy output in relatively light free environments. The chloroplasts would be taken on later so: SA -> SP. While we can be sure that single cell plants produced multicell plants (SP -> MP) we don't know if it was single cell animals leading to multicell animals (SA -> MA) or a jack-of-all-things multicell plant through gamete mutation producing the proto-multicell animal(MP -> MA), though the former (SA -> MA) is more likely. Another possibility, though much less likely is SP -> SA -> MA, in which some SP lost its chloroplast after gaining some important adaptation which allows it to produce the modern SA that in turn evolved to MA.

Maybe it went something like:

SA-->SP-->MP
 | 
 --->MA

or

SA-->SP-->MP
           |
           -->MA

or

oldSAs-->SP-->MP
          |
          --->newSA-->MA

Likely only genetic and/or fossil studies can further elucidate this. Sjschen (talk) 15:07, 19 April 2010 (UTC)

Thanks. So it looks like it's still an open question. I thought plants must have come first, since animals need them to eat. Apparently, animals must have eaten other organisms, before there were plants. StuRat (talk) 17:19, 19 April 2010 (UTC)

The first living things were chemosynths, which don't really fit in either "plants" or "animals". --Carnildo (talk) 01:12, 20 April 2010 (UTC)

OK, but then how did we get from those to single and multi-celled plants and animals ? StuRat (talk) 13:42, 20 April 2010 (UTC)

football effecting brain

does taking heads(in football) harms your brain(means unabling the brain to do something,anything)?

but here is a simple explanation that when u take head there is jerk on ur head so damage is inevitable.

well i don't think so as our brain is well secured in a bony box ie skull and also for further safety there is 3 layered membrane filled with a fluid absorbing shocks.

I THINK IT IS JUST A MISCONCEPTION —Preceding unsigned comment added by Myownid420 (talk • contribs) 17:41, 16 April 2010 (UTC)

Well, you're wrong. The brain has a lot of protection, but it is so soft and squishy that a hard blow to the head can seriously damage it anyway. Looie496 (talk) 17:51, 16 April 2010 (UTC)

I remember reading some time ago that this is a danger and that professional footballers and others were advised to avoid them. Cannot recall where I saw it, but I often look at health section of the BBC news-site, and that would be the sort of thing they'd cover. 78.151.110.54 (talk) 18:38, 16 April 2010 (UTC)

Jeff Astle, one of West Bromwich Albion's most famous players, died from a brain disorder which was ascribed at the inquest to repeatedly heading a football. I would point out, however, that he was active in the 1960s and 70s when footballs were made of leather and became even heavier in wet English conditions. [2] --TammyMoet (talk) 19:19, 16 April 2010 (UTC)

See Dementia pugilistica. At the bottom of the article it notes that it's been diagnosed also in player(s) of American football and professional wrestling. Comet Tuttle (talk) 20:47, 16 April 2010 (UTC)

Yes it certainly does, and those are just the first four google hits. ~ Amory (u • t • c) 20:52, 16 April 2010 (UTC)

45% of some professional footballers tested had brain injuries from heading, according to http://news.bbc.co.uk/1/hi/health/176392.stm 78.146.229.142 (talk) 12:19, 17 April 2010 (UTC)

See also concussion. ~AH1^(TCU) 15:50, 17 April 2010 (UTC)

Closed head injuries regularly result in brain damage. Yes, the structure of the brain cavity is such as to provide a good deal of protection, but that doesn't mean it's set up to take repeated and/or intense impact. The hardness of the skull may even serve to damage the brain as much as to protect it (as in contrecoup injuries, which often result in worse damage from the brain bouncing around inside the skull than from the impact itself). A friend of mine who used to volunteer at a rehabilitative clinic told me that some of the brain-injured individuals there suffered severe and permanent damage from activities as innocent as getting out of bed, slipping on the rug, and striking the head on the edge of the nightstand. It seems logical, then, that there would be at least an element of risk in an activity that involves a sizable, fast-moving object colliding with the head. See Association football headgear. Furthermore, although most people who have suffered a concussion or two in the course of their lifetime recover with no lasting effects, frequent concussions may lead to neurodegeneration (the abovementionted dementia pugilistica). When the brain suffers a concussive blow while still under the effects of a previous concussion, death or permanent damage is possible from a rare condition called second-impact syndrome, most often seen in young athletes. If you do play a sport that puts you at high risk for concussion (football/soccer, American football, boxing, etc.), be familiar (and make sure your teammates are familiar) with the symptoms of concussion and DON'T RETURN TO THE GAME after a head injury until you've been medically cleared. 71.104.119.240 (talk) 21:06, 20 April 2010 (UTC)

Movie about the "representative town in sampling"

I have a vague recollection there is a movie about a town (in US) that was seen for a time as a very representative town, with regards to sampling (it's population was seen as very "average"). Half an hour of googling and looking through Wikipedia categories and articles gives me nothing. Any suggestions? --_{Piotr Konieczny aka Prokonsul Piotrus| talk} 17:54, 16 April 2010 (UTC)

Will_it_play_in_Peoria?#Peoria_as_test_market -- Coneslayer (talk) 17:58, 16 April 2010 (UTC)

Interesting, but I see nothing about a movie. I am pretty sure I read about something similar in the context of a movie made of it (or a book? Hmmm.). --_{Piotr Konieczny aka Prokonsul Piotrus| talk} 18:47, 16 April 2010 (UTC)

I googled for "most typical american city" (as four words, not a phrase) and that quickly turned up the key word "Middletown". In Wikipedia, Middletown links to Middletown studies, which links to Magic Town, which I believe is the movie you want. --Anonymous, 05:22 UTC, April 17, 2010.

Yes, I believe this is what I was looking for. Thank you both, --_{Piotr Konieczny aka Prokonsul Piotrus| talk} 06:08, 17 April 2010 (UTC)

Largest Recorded Solar Flare

When was the largest recorded solar flare? According to this, it was recent. But according to this, it was in 1972. --Reticuli88 (talk) 18:46, 16 April 2010 (UTC)

The recent one seems to have been measured with a new device. Also, the wikipedia article could be outdated. Most other sources cite the 2003 one. --Cheminterest (talk) 00:46, 17 April 2010 (UTC)

The Carrington Event in 1859 was likely the biggest geomagnetic storm ever recorded from a solar flare that hit the Earth. ~AH1^(TCU) 15:48, 17 April 2010 (UTC)

Escape velocity

Escape veocity is said to be the amount of speed necessary to escape an body's gravitationa (or whatever) field. This is usually said to be independent of the launch angle, because kinetic energy is a function of the speed, not velocity, of an object. I think this is a mistake though. If an object were to be launched at an angle to the horizontal, even though it may have the energy necessary to reach an infinity height, its trajectory won't allow it to, because when it reaches its maximum height, it will still have some speed, just perpendicular to the direction of gravity. Am I right? Does the radial component of the velocity have to equal the escape velocity? 173.179.59.66 (talk) 20:11, 16 April 2010 (UTC)

You are right. Wikipedia has an article about Escape velocity. Cuddlyable3 (talk) 23:19, 16 April 2010 (UTC)

But the article indicates that the object will undergo a parabolic trajectory if shot at an angle, which would take it to infinity, no? 173.179.59.66 (talk) 00:18, 17 April 2010 (UTC)

The article is right. The component of the velocity perpendicular to the direction of gravity will steadily decrease as the object moves away from the planet allowing the object to scape. Just remember that the direction of gravity is changing as the object moves along the orbit. Dauto (talk) 01:25, 17 April 2010 (UTC)

In the case of a spherically symmetric 1/r² field, the closed (elliptical) orbits all have a total energy smaller than the escape energy, so whether you get a closed or open orbit does depend only on the speed. In general, though, there can be closed and open orbits passing through the same point with the same speed, in which case it does matter which way you throw. (But can that happen in Newtonian gravity in 3 dimensions? I don't know.) -- BenRG (talk) 05:19, 17 April 2010 (UTC)

To put it plainly, the original poster is wrong and Cuddly is wrong to agree. As long as the object is not slowed by collision or by air friction, its direction doesn't affect whether it will escape or not, only its speed does. The original poster's reference to "its trajectory won't allow it" appears to assume that it will start falling, but it never will. --Anonymous, 05:30 UTC, April 17, 2010.

What I meant by "its trajectory won't allow it" is the following: suppose we are dealing with an object travelling near the earth's surface. If we want this object to reach a height h, buy the conservation of energy we want the ball to have a speed v = sqrt(2gh). But this will only work if the object is shot up perpendicular to the surface. If it is shot at a bit of an angle, then its apex will lower than this max height.

Now when it was originally presented to me, the escape velocity was calculated by the conservation of energy. That is, mv²/2 = GMm/r, and solve for v. However, it is then said that, because speed is a scalar and doesn't depend on direction, this works regardless of the angle it is launched at. However, drawing a parallel to the example I gave above, it seems perfectly reasonable that an object launched at the escape velocity at an angle won't reached r = infinity (ie its maximum height), even though it would have the energy to do so. So it appears, at least to me, that further analysis is required to justify that escape velocity is independent of launch angle, beyond looking at potential and kinetic energy. Is this correct? 173.179.59.66 (talk) 06:04, 17 April 2010 (UTC)

The only reason the object might not "escape" at lower angle is that it would remain in the atmosphere for longer, and would thus lose some of its initial energy, bringing its "total energy" below escape energy. On a (spherically symmetric) planet (see comments below) without atmosphere or mountains, escape velocity will allow escape at any angle above zero. Dbfirs 08:41, 17 April 2010 (UTC)

The OP is right, as I said above. In, say, a spherical 1/r⁴ field, circular orbits have a total energy that's larger than the energy at infinity, but they're nevertheless closed (though unstable—but you can construct a potential where they're stable too). That doesn't happen in Newtonian gravity in three dimensions with spherical symmetry, but it's not self-evident that that's the case. I don't know if it can happen in Newtonian gravity in three dimensions without the assumption of spherical symmetry. -- BenRG (talk) 10:18, 17 April 2010 (UTC)

Energy calculations do not take into account the physical size or shape of the Earth (or other planet). If you launch an object exactly horizontally with a speed greater than escape velocity then it enters a hyperbolic orbit whose perigee is at the launch point (because launch is horizontal). This is its closest approach to the center of the Earth. So as long as you assume a spherical Earth (and, of course, no atmosphere) then yes, the object will escape to infinity, even though initially it has no radial velocity - this is illustrated at the top of the escape velocity article. But if you have a non-spherical Earth (and the OP seems to be assuming a flat Earth) or launch at an angle below the horizontal then the orbit may intersect the surface of the Earth at some point after launch - conservation of energy does not forbid this. This is what escape velocity#Orbit says - an object can be above escape velocity but not on an escape trajectory. Gandalf61 (talk) 11:12, 17 April 2010 (UTC)

Okay, I see what you're getting at now with the "trajectory" thing. When we're talking about objects near the Earth's surface moving at moderate speeds, it is indeed true that if you launch an object diagonally instead of vertically, it won't rise as high. That's because only the upward component of its initial velocity is directed opposite to the gravitational acceleration, so it's eliminated sooner while the horizontal component remains unchanged. You can easily compute that, ignoring air friction, its path is a parabola.

But that analysis is based on the assumption that the Earth is flat! This is good enough for that particular case, but it's not the truth. That "parabolic" curve is actually the tip of a long narrow elliptical orbit reaching down inside the Earth, with its other end just beyond the Earth's center.

When you're dealing with an object moving at escape velocity, you can't ignore the shape of the Earth any more. If you imagine a trajectory where the object does not go on rising, that trajectory must be an orbit -- an ellipse. And for any particular orbit, there is only one possible speed for an object at any particular point in that orbit. And if you calculate the speed your object has remaining after it has risen to any particular altitude, it will always be faster than the speed for that point on any elliptical orbit.

To really prove it it'd be necessary to do the calculations, which I'm not going to attempt now, but I hope this explanation will at least help make it more intuitive why it works as it does.

Oh, one more point I should have made. Ignoring air friction, once an object is launched at a particular speed, its speed from then on is only a function of its altitude. For example, say you launch a ball vertically at 70 mph and at a certain height it has slowed to 30 mph. If you launch it diagonally at 70 mph and it reaches the same height before it starts dropping, then its speed at that height will again be 30 mph. The tradeoff between kinetic and potential energy is the same no matter what path it takes, right? Well, when I said that the speed would be too fast for it to be in an elliptical orbit, this principle explains how you would know what the speed will be. --Anonymous, 11:51 UTC, April 17, 2010.

So if I understood what was said, it would take a study of orbital mechanics and Newtonian gravity to understand the escape velocity result, right. Thanks a lot! 173.179.59.66 (talk) 15:27, 17 April 2010 (UTC)

Well no, just understand that the Earth is round. Even if you are moving mostly horizontally you will eventually be moving away from the Earth. John Riemann Soong (talk) 19:06, 17 April 2010 (UTC)

Also instead of thinking of maybe a rocket and Earth, think an electron and an atomic nucleus. (The nucleus is massive enough that it moves very slowly in our timeframe.) For a certain velocity less than V_e, you can even orient it totally vertically and it would be in a degenerate orbit (passing right through the nucleus) and you will get an orbit oscillating along the y-component. This excludes any quantum mechanical effects, of course. John Riemann Soong (talk) 19:13, 17 April 2010 (UTC)

It's just amatter of conservation of energy and angular momentum. Dauto (talk) 03:27, 18 April 2010 (UTC)

beer

i quit drinkin. whats the best tasting brand of non-alcohol beer sold in the usa? —Preceding unsigned comment added by Jonny12350 (talk • contribs) 21:42, 16 April 2010 (UTC)

i found a list of them please choose which i should buy

http://www.wegmans.com/webapp/wcs/stores/servlet/ProductListView?forwardto=ProductListView&Ne=5&Ntt=non-alcoholic%20&langId=-1&Ntk=ProductSearch&storeId=10052&Ntx=mode%20MatchAllPartial&catalogId=10002&N=207&Nty=1 —Preceding unsigned comment added by Jonny12350 (talk • contribs) 21:46, 16 April 2010 (UTC)

This is impossible to answer. The best one for you is the one you like the best (other factors such as cost, availability and so on being taken into account). Put your question another way: "what is the best tomato I can buy"? and you'll see there's no sensible answer. However in my experience (yes, this is original research) all non-alcohol beers are easily describable as "worst". Drink soda or fruit juice instead. Tonywalton ^Talk 00:21, 17 April 2010 (UTC)

The best non-alcoholic beer ? Root beer. StuRat (talk) 01:59, 17 April 2010 (UTC)

Corona (beer). Pretty much non-alcoholic. 173.179.59.66 (talk) 06:10, 17 April 2010 (UTC)

No, it isn't. Dauto (talk) 19:59, 17 April 2010 (UTC)

Speaking of root beer, don't forget about ginger ale. ~AH1^(TCU) 15:45, 17 April 2010 (UTC)

Looks like this is your chance to try a few different brands of non-alcoholic beer - and other beverages - until your taste buds make their expert decision. Have fun. 71.104.119.240 (talk) 21:12, 20 April 2010 (UTC)

Help comprehending units of energy

I can visualize most physical units, for example, I know about how much force a Newton is ("It's like me pressing down this hard"). However I find it very hard to comprehend a joule. Obvioulsy something that is moving has kinetic energy, but how do we quantify it? I am having trouble understanding exactly how much energy a "joule" is, probably because energy doesn't seem like something that one can have "amounts" of. I know this is an extremely hard request but can any of you help me visualize energy?--92.251.148.126 (talk) 23:00, 16 April 2010 (UTC)

Run up a mountain all day without eating. Do you feel hungry? Now you know what energy is. Cuddlyable3 (talk) 23:16, 16 April 2010 (UTC)

Yeah I knew what it was but "how much" is a joule? It doesn't seem to be something quantifiable.--92.251.148.126 (talk) 23:17, 16 April 2010 (UTC)

Why doesn't Orders of magnitude (energy) help? For that matter how about the Calorie? Nil Einne (talk) 00:05, 17 April 2010 (UTC)

I kind of take 92's point. Is it because a unit like a Calorie is defined in terms of other quantities? For example in the definition of the Calorie: the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius one can directly perceive what a kilogram feels like (lift a bag of sugar) and what a temperature rise feels like (OK, perhaps not a 1°C rise, but you can directly perceive a temperature change), but you can't directly feel, see or hear the energy making the change. Tonywalton ^Talk 00:31, 17 April 2010 (UTC)

A joule is defined as the work done when a force of one newton pushes an object one meter, or one coulomb of electrons (a very large number) is pushed through a voltage of one volt. --Cheminterest (talk) 00:50, 17 April 2010 (UTC)

There we are again. The quantities you mention as defining a joule are physically palpable; you can feel a force (whether or not you can accurately tell whether it's 1N) and you can see, or walk, a distance. 92, might the article on Dimensional analysis be of interest? By the way, I'm not sure about your definition of a joule there, Cheminterest; surely the mass of the object you're pushing comes into it somewhere, and isn't work measured per time? Tonywalton ^Talk 01:03, 17 April 2010 (UTC)

Cheminterest's explanation is correct, the mass of the object is irrelevant for the definition of work. It is power that is the quatity defined as energy per time. You asked about how to better understand the unit of energy but what you really want is to understand the concept of energy. Once you do that, then the units will make more sense. Sure, energy is slighly more abstract than force or distance, but only slightly so. Dauto (talk) 02:27, 17 April 2010 (UTC)

Apologies, of course it's correct. My fault entirely for misreading it. Tonywalton ^Talk 00:12, 21 April 2010 (UTC)

If an average sized apple has a weight (not mass) of 1N on Earth then you lifting that apple up by 1 metre would mean you have done 1 joule of work to that apple. --antilived^{T | C | G} 13:43, 17 April 2010 (UTC)

We have Joule#Practical examples. It is fairly self-explanatory. (Except maybe the one with a drop of beer, which is a bit counter-intuitive, no pun intended. Beer has about half a kilocalorie of food energy per gram; that is roughly 2 kilojoules of food energy per gram. A beer drop that weights about 0.05 gram has about 100 joules of food energy. Not all of it can be used for work, of course, so a drop of beer is probably not enough for you to throw a 2 kg projectile at 10 m/s). --Dr Dima (talk) 06:20, 17 April 2010 (UTC)

c and si

C(carbon) and Si lie in same group.why compound co(carbon mono oxide ) is formed but SiO is not formed .plz explain —Preceding unsigned comment added by 119.154.126.225 (talk) 23:35, 16 April 2010 (UTC)

Actually, it does. See Silicon monoxide. It's just quite rare as it is not very stable (neither is CO, which is why it is not formed in nature. But cars don't burn silicon). Hope this helps, --The High Fin Sperm Whale 00:22, 17 April 2010 (UTC)

That's "quite rare" under normal Earth conditions (we have an atmosphere fairly rich in oxygen, after all, which tends to oxidise most things given half a chance). The article you linked states that "... [SiO] has been described as the most common oxide of silicon in the universe". Wish cars did burn silicon. Stuffing rocks into the tank would be much cheaper than using petrol, and rocks are easier to find than crude oil. Tonywalton ^Talk 00:40, 17 April 2010 (UTC)

About your note about rocks burning silicon: Rocks already contain silicon in an oxidized state. It cannot be burned any more, just like carbon dioxide cannot be burned. An oxidizible silicon compound such as SiO or silane would be a fuel, though. --Cheminterest (talk) 00:52, 17 April 2010 (UTC)

Good point, though CO₂ can be burned; just stuff something hot enough and oxygen-greedy enough into it (a lump of burning magnesium will do the trick, you get magnesium oxide and soot, aka carbon). I wonder if anything cheap could provide enough energy to dissociate SiO₂ in the same way, thus providing silicon out of my car's exhaust pipe which I could sell to Intel or TI. Hmmm...Tonywalton ^Talk 01:17, 17 April 2010 (UTC)

Anything strong enough to reduce silicon oxides (or carbon dioxide) isn't going to be found in nature: it would have long ago reacted with oxygen. If you did find something that strong, you'd just burn it instead (in oxygen) to get much more energy released. Buddy431 (talk) 14:13, 17 April 2010 (UTC)

You aren't burning the CO2, you are burning the magnesium. The CO2 would be the oxidizer (not the fuel). Ariel. (talk) 01:59, 18 April 2010 (UTC)