Whitefire

Thank you!

I am trying to grasp some concepts, perhaps relativity forum would be better for this - sorry if so. My question is directed to all who are familiar with concept of wave–particle duality and Young's double slit experiment. Out of curiosity (and being too lazy to try and do the calculations myself), I tried to search the Internet and find out how many photons can a bulb emit in 1 second. Answers varied from 2.5 x 10^13 to 5.5 x10^32. Well, it doesn’t really matter (don’t think I don’t understand that bulbs may vary), but the point is, the number is definite. Huge, but not endless. For the sake of clarity, let’s assume that a given bulb emits a little smaller number of photons per second, say, 1 000 000 000. Now let’s assume that this bulb is being observed from a distance of 10 000 kilometers by numerous observers or observing devices. The devices are placed along the surface of a sphere surrounding the source of light. There is one device per every square meter, which adds up to total: The surface area A of a sphere with r = 10 000: A = 4πr^2 A = 1 256 000 000 This means there are about 1 256 million devices. Now, final assumption: imagine they are all capable of registering light from 10 000 kilometers away, and they are all pointed at our little bulb, which was turned on for 1 second and emitted 1 000 000 000 photons. What do the devices see? Does each 'catch' 1 photon, or is it only an average? What can be seen by the devices that have no photons left to observe?

I know this and it doesn't explain entropy. The opposite is possible - actually it's the same. What you describe is "getting warmer". The opposite would be "getting colder" and it has the same description. It would be better to call it "merging" of temperatures. But is it possible to make hot atoms ("balls") influence larger structures? Or maybe using heat (faster "balls") to create movement of electrones (electricity). It should be doable. Imagine a long rod of, say, copper. We leave it on a desert. In a day it is 1m long, at night 99 cm. So it does some mechanical work all by itself. It's just not very efficient. Btw, does any of you know anything about the relation of pressure and temperature? If I squeezed that copper rod on a desert, would it prevent it from going hotter?

Thanks Right - entropy is exactly the word I was looking for. Thank you! But I don't think this fully answers my question. Don't take me wrong, I know we are unable to make "high temperature --> low temperature = energy" work. I am asking why. Is there any molecular explanation for entropy? Heat pumps are ok, but I think they need some pretty high temperature, don't they? Plus they are just pumps, not engines.

What exactly makes it so difficult to obtain energy from what we call "heat"? It seems that by making things colder, we should get the energy back. There's so much talk about global warming, and that it comes from additional energy of the sun, stopped in our atmosphere by CO2 etc. On the other hand, we are always short on energy, always looking for more sources, nuclear and what not. It would be wonderous if we could use the first problem to solve the other, would it not?