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Scientists report asymmetry between heating and cooling

phys.org

91–100 of 139 posts

Re: Scientists report asymmetry between heating and cooling

#91
post #68

Earlier quoted context omitted.

Heating and cooling are rarely nicely split up in time. While you're heating something it is also cooling and while you're cooling something it is also warming up. This usually limits your ability to heat something up or to cool it because at some point these two are in balance.

No. Put a cold thing into something hotter and the thing will heat up without cooling.

You mean putting cold ice cubes into a warmer drink doesn't cool it down?

Re: Scientists report asymmetry between heating and cooling

#92
post #76

Earlier quoted context omitted.

the hot thing will get cooler. like to make something clean, you have to make something else dirty.

Is that true though? If I have say a box with mixed red and blue bricks and I sort them by color, both sides are "clean" now.

Cleaning is usually relocating dirt.

If either red or blue were dirt, one of the sides is dirty, and the other is clean.

If neither red or blue were dirt, then nothing was dirty, it was just mixed up.

Re: Scientists report asymmetry between heating and cooling

#94
post #68

Earlier quoted context omitted.

No. Put a cold thing into something hotter and the thing will heat up without cooling.

No. The outer layer of the hot thing will quickly heat up to the temperature of the hot medium, then it will cool down as is stays in contact with the middle layer, which will heat up itself. The same thing repeats in layers all over the object.

Your idea is inconsistent with the heat equation and with basic materials science. What do you derive this model from?

Re: Scientists report asymmetry between heating and cooling

#95

Earlier quoted context omitted.

They experimentally demonstrated that it takes significantly more energy to move a microparticle the same distance when cooled than the amount of energy it would take when heated.

How can that be possible, though?

If something is already bumping around randomly, all you need to do is constrain the bumping along some dimensions and it will move less randomly and more frequently toward the remaining free dimensions.

That's easier than having to provide all the energy to do the movement directly.

Re: Scientists report asymmetry between heating and cooling

#96

Earlier quoted context omitted.

How can that be possible, though?

If something is already bumping around randomly, all you need to do is constrain the bumping along some dimensions and it will move less randomly and more frequently toward the remaining free dimensions. That's easier than having to provide all the energy to do the movement directly.

Constrained energy basically acts as mass right? So would an intuitive way to think of this be that the warm particle has more energy, but moving it confines where that energy can be so it behaves as if it has more mass?

Re: Scientists report asymmetry between heating and cooling

#98
post #25

Earlier quoted context omitted.

Meh, if self-assembling, self-repairing materials forming a swarm of nano bots was going to take over the world it would have already happened elsewhere in the universe and proliferated everywhere by now. instead we have biology. The actual dominate force in our dimension that did proliferate.

Do you have any evidence that us biologicals are not an outlier other than the anthropic principle? Maybe our solar system is in the machines’ nature preserve sector.

Nope, strictly by objective evidence we are alone as you know.

Our “dimension” the one unique to our perception and interpretation on Earth is dominated by biology.

I don’t see an artificial system being able to sustain a supply chain long enough to defeat that. The supply chain of biology is inherit.

Re: Scientists report asymmetry between heating and cooling

#99
post #3

I always feel a little stupid or strange reading a lot of these science headlines and introductions. I wasn't aware that people considered there to be a symmetry between heating and cooling. I thought that the entire point of thermodynamics is that they are asymmetric. Even the article mentions that it's been known that heating is more efficient than cooling.

Given that cooling is effectively just heating something else, I’m a little surprised.

Cooling is heating everything else.

The symmetry between cooling and heating is only a linearization approximation, like also the symmetry between compression and expansion.

There is no surprise that there are scenarios when the approximations deviate too much from the actual behavior and cooling and heating are asymmetric (and also compression and expansion).

Re: Scientists report asymmetry between heating and cooling

#100
post #3

I always feel a little stupid or strange reading a lot of these science headlines and introductions. I wasn't aware that people considered there to be a symmetry between heating and cooling. I thought that the entire point of thermodynamics is that they are asymmetric. Even the article mentions that it's been known that heating is more efficient than cooling.

I used to live in Florida and it costs me a lot more to heat the house than cooling it even though the outside temperature rarely went below 32F (and I kept the home at 74F in the winter and 78F in the summer)...
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