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Not really related of the article, but a question I just realized I don’t know the answer to: where does the temperature of an atom “live”? Is it entirely in th

Not really related of the article, but a question I just realized I don’t know the answer to: where does the temperature of an atom “live”? Is it entirely in the electrons? Does the nucleus have any temperature?

thriftwy 3y ago
https://physics.stackexchange.com/q/716282/43345 https://physics.stackexchange.com/q/716282/43345 discovered by me some time ago. Long story short, nucleus cannot absorb low temperature thermal energy so it's virtually zero.
staunton 3y ago
The "temperature of an atom" is something very different from the temperature of a material with billions of atoms. For the material, what matters most is usually vibrations of atoms, where the nucleus contributes the most to kinetic energy, because it is heavy, and the electronic configuration contributes to potential energy. For an atom, you basically have to do quantum physics and talk about von Neuman entropy of it's quantum state. This kind of temperature is very removed from the everyday concepts of "heat" and "heat transfer".
ianburrell 3y ago
Temperature is the motion of the whole atom. Individual atoms don't really have temperature, temperature is a bulk property, the average of motion of lots of atoms.
radioactivist 3y ago
That's a good question. it depends how long you wait and how strongly coupled they are. For electrons and nuclear motion they are often strongly coupled enough that they quickly reach equilibrium and thus are at the same temperature (e.g. in liquids or solids). But on short timescales they can absolutely be at distinct temperatures. In dilute gases they can also become somewhat decoupled (there can be a well defined electronic temperature and nuclear temperature). One case whether this can take a much longer period of time is when dealing with nuclear spin -- this is much more weakly coupled to the electrons and so can take much longer to equilibriate.
NL807 3y ago
Not a physicist, but I think temperature lives in motion of particles, let it be electrons, the nucleus, whole atoms, or otherwise. Because electrons shroud the nucleus and have much less mass, they are more prone with external interactions where they can change momentum by absorbing and releasing energy. The nucleus is not exempt from this, but takes a not more energy to change their momentum. That being said, "temperature" as we are accustomed to, is more like a statistical average of the total motion of all particles in the system.

thriftwy 3y ago

https://physics.stackexchange.com/q/716282/43345 https://physics.stackexchange.com/q/716282/43345 discovered by me some time ago. Long story short, nucleus cannot absorb low temperature thermal energy so it's virtually zero.

staunton 3y ago

The "temperature of an atom" is something very different from the temperature of a material with billions of atoms. For the material, what matters most is usually vibrations of atoms, where the nucleus contributes the most to kinetic energy, because it is heavy, and the electronic configuration contributes to potential energy. For an atom, you basically have to do quantum physics and talk about von Neuman entropy of it's quantum state. This kind of temperature is very removed from the everyday concepts of "heat" and "heat transfer".

ianburrell 3y ago

Temperature is the motion of the whole atom. Individual atoms don't really have temperature, temperature is a bulk property, the average of motion of lots of atoms.

radioactivist 3y ago

That's a good question. it depends how long you wait and how strongly coupled they are. For electrons and nuclear motion they are often strongly coupled enough that they quickly reach equilibrium and thus are at the same temperature (e.g. in liquids or solids). But on short timescales they can absolutely be at distinct temperatures. In dilute gases they can also become somewhat decoupled (there can be a well defined electronic temperature and nuclear temperature). One case whether this can take a much longer period of time is when dealing with nuclear spin -- this is much more weakly coupled to the electrons and so can take much longer to equilibriate.

NL807 3y ago

Not a physicist, but I think temperature lives in motion of particles, let it be electrons, the nucleus, whole atoms, or otherwise. Because electrons shroud the nucleus and have much less mass, they are more prone with external interactions where they can change momentum by absorbing and releasing energy. The nucleus is not exempt from this, but takes a not more energy to change their momentum. That being said, "temperature" as we are accustomed to, is more like a statistical average of the total motion of all particles in the system.