Heat Transfer...?

Question

Even though the odds are un-imaginably small, but considering the life-time of our universe, and the size, and amount of 'objects' there are, do you think its possible that heat has been transferred from cooler region to a hotter region, ie the cold region became colder and the hotter region became hotter at some point, even on the smallest scale?

Heat energy reaches thermal eq due to that being the most probable energy-distribution, but there is a finite probability that it doesn't, so no it doesnt always reach eq, hence my question...

Answer 1

engery or heat will try to equalibrize, meaning, heat will always try to move from something hotter to something colder.

Answer 2

This is a good question, and its one about what the odds are.

Imagine 12 molecules in a box, 6 hot (fast) and 6 cold (slow).

On average, 1/2 are moving to the left and 1/2 to the right at any time. So the chances that all the hot molecules are randomly moving to the left is 1/2 x 1/2 x 1/2 x 1/2 x 1/2 x 1/2 or 1 in 64, and the same for all the cold molecules moving to the right. So there is only a 1/64 x 1/64 or 1/4096 chance that the mocules are moving so that they will randomly separate into hot and cold (of course, were they to do so it would in no way violate the laws of conservation of energy or thermodynamics - those who think it would should think hard about why they are wrong - they clearly do not understand what these laws say).

Now in a real gas there are around 10 ^ 23 molecules per mole of gas. If 12 molecules gave us odds of 1 in 4096 can you imagine the odds for 10 ^ 23!! It is hugely against this happening, so much so that the universe could go on for many billions and billions and billions and billions and .... of times its current age without this occuring anywhere by chance anywhere in the universe.

Or of course you could just get lucky.

Answer 3

Heat transfers from a hot body to a cold one, but not vice versa.

This can be explained using gaseous bodies.

In the gaseous bodies, such a process can be visualised as a mixing of fast molecules with slow ones. If heat is to transfer from cold one to hot one, it would constitute a sorting out of fast and slow molecules, i.e., a transition to a more orderly state.

Using a shovel, we can rapidly mix the contents of two sacks of grain. However, we can continue to mix the contents of these two sacks endlessly with out the grain separating in such a manner that one of the grain varieties appears above and the other below.

The number of kernels in the sacks is immeasurably less than the number of molecules in a cubic millimeter.

Consider there are N molecules in a box. Assume that the box is divided into a thousand million cells. The probability that N molecules are distributed in all cells except one is equal to 0.999999999^ N. At first glance, it may appear to be a value close to unity. Using N = 10^23 the value is nearly 10^-4 X 10^ 19.

To write this number in decimal form, it will take more than 300,000 million years even if one writes 3 zeros per second.

Answer 4

You're thinking of Maxwell's Demon thought experiment. James Clerk Maxwell developed those famous and annoying equations, well for any engineering or physics major, that helped Einstein formulate his two theories of relativity. Anyway...
Even though normally entropy increases, at the quantum level in can decrease. This is always a possibility. Like having ice cubes form in a glass of tea that cold water has been poured into. Yes, through quantum mechanics it is possible, just very improbable. With the wave of possible outcomes of this scenario it is more likely that the tea will get cooler and more diluted, not that the water will lose its lower amount of heat to the tea and solidify into ice cubes, but that is still a possible outcome. I think Gamow's book about poor Mr Tompkins has a little thing about coffee or something and the devil in the details.

Answer 5

Heat transfer from colder region to hotter region would simply violate the 2nd Law of Thermodynamics (irrespective of the timescale involved) which till date does not have any recorded violations(citations required). This covers the timescale part of your Q.
However, on going to the smallest scale(subnuclear and lower) I don't know whether the concepts of 'hot' or 'cold' will have any meaning since it(temperature) is a statistical property. 'Heat transfer' on such scale would certainly be an interesting research topic!

Answer 6

very hard to determine, although it is usually the other way round ie heat and cold sort of neutralise each other during heat transfer, there are sort of micro climates in the universe that might distort such a situation.

Answer 7

Be careful not to confuse quantum behavior with macromoleculear behavior. There are different rules for each.

Answer 8

WHY OF COURSE!!!
Look around u! Is that not what happens in ur refrigarator or a.c.??
P.S.- This requires external energy. It can NEVER HAPPEN SPONTANEOUSLY.