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Scientists report asymmetry between heating and cooling

phys.org

111–120 of 139 posts

Re: Scientists report asymmetry between heating and cooling

#111

My first thought upon reading the article was that absolute zero bounds coldness whereas there is no limit to how energetic a particle or bulk can be. Am I on the wrong track?

Actually there are temperatures below zero Kelvin, but they are hot https://en.wikipedia.org/wiki/Negative_temperature

Re: Scientists report asymmetry between heating and cooling

#112

Earlier quoted context omitted.

> On the other hand, cooling at the microscopic level involves the release of energy from individual particles, resulting in a dampening of their motion. This process corresponds to the system losing energy, leading to a decrease in the intensity of particle movement. It actually makes sense, doesn’t it? Heating the object adds energy constructively. In cooling, energy removed from one particle may in fact be absorbe…

Wait so hot objects have molecules with greater nuclear energy? This seems wrong. Are they emitting energy like radiation? I suppose that makes some sense, and would in fact support the asymmetry. Without thinking about it I thought heat was kinetic energy. And I don't see how collisions would transfer kinetic energy in positive direction any better than negative direction.

Hot molecules move faster, it’s just kinetic energy.

Re: Scientists report asymmetry between heating and cooling

#113
post #73

Earlier quoted context omitted.

> I wasn't aware that people considered there to be a symmetry between heating and cooling Same here. By analogy, while any chemical reaction is in principle reversible, the kinetics "forward" and "backward" are unlikely to be equally favorable. Likewise, with atomic nuclei, fission and fusion tend to be favored under distinctly different conditions. The article does mention "far from equilibrium." Could this be a ca…

No. This research is all about far from equilibrium systems, which also happens to be the realm of life. There IS symmetry near equilibrium, and I think a high school level of thermodynamics would expect it to be symmetric. In comparison with the high school chemistry which already considers enough phenomena to get meaningful asymmetry easily. I’m surprised at the level of surprise here, it seems motivated by some ki…

My last sentence there, about a caveat, was silly of me, beyond mere HN affectation.

Re: Scientists report asymmetry between heating and cooling

#114

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.

Why would that apply to synthetics but not to biologicals?

Ecosystem vs synthetic supply chain.

Re: Scientists report asymmetry between heating and cooling

#115
post #109
post #91

Earlier quoted context omitted.

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

The ice cubes will only get warmer and will never get cooler.

I don't think you understood me. I meant the drink gets cooler.

Re: Scientists report asymmetry between heating and cooling

#116
post #112

Earlier quoted context omitted.

Wait so hot objects have molecules with greater nuclear energy? This seems wrong. Are they emitting energy like radiation? I suppose that makes some sense, and would in fact support the asymmetry. Without thinking about it I thought heat was kinetic energy. And I don't see how collisions would transfer kinetic energy in positive direction any better than negative direction.

Hot molecules move faster, it’s just kinetic energy.

If this were the case, then how can a solid have a temperature at all? Especially crystalline solids, where all the molecules/elements are bound in a lattice?

Re: Scientists report asymmetry between heating and cooling

#117
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.

Other than the outer surface of the object there are no layers.

Re: Scientists report asymmetry between heating and cooling

#118
post #116
post #112

Earlier quoted context omitted.

Hot molecules move faster, it’s just kinetic energy.

If this were the case, then how can a solid have a temperature at all? Especially crystalline solids, where all the molecules/elements are bound in a lattice?

The molecules in a crystal still vibrate kinetically. A solid with no molecular motion would be at absolute zero temperature.

Re: Scientists report asymmetry between heating and cooling

#119
post #112

Earlier quoted context omitted.

Wait so hot objects have molecules with greater nuclear energy? This seems wrong. Are they emitting energy like radiation? I suppose that makes some sense, and would in fact support the asymmetry. Without thinking about it I thought heat was kinetic energy. And I don't see how collisions would transfer kinetic energy in positive direction any better than negative direction.

Hot molecules move faster, it’s just kinetic energy.

And heating/cooling is just transfer of kinetic energy? Seems strange if so.

Re: Scientists report asymmetry between heating and cooling

#120
post #109

Earlier quoted context omitted.

The ice cubes will only get warmer and will never get cooler.

I don't think you understood me. I meant the drink gets cooler.

I told you what I meant. Of course the drink gets colder, but that is not what we discuss.
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