Question from a layperson: Particles & temperature

[AlexanderinCbus]

Hello! First post here so go easy on me. I am a Physics enthusiast, but I fear I am a layperson when it comes to the field. Most of what I know comes from low level college classes and the youtube channel PBS Spacetime.

I have a question that might be a ridiculous one. But here goes. (Go easy on me).

I keep reading and seeing in youtube vids that temperature is the measure of kinetic energy of particles in motion. So my question is if you could magically shrink yourself down to the size of a proton (or even smaller to the size of an electron) and touch one of those particles, would it feel warm? i.e. If temperature is simply how fast the particles are moving, do the particles themselves exist without temperature? Am I thinking about it all wrong? I'm curious and want to know.

 

[Khashishi]

No, single particles can't have temperatures. Temperatures can only be defined for macroscopic bodies with many degrees of freedom.

 

[sirios]

hi, the answer is, no, because individual particles are devoid of temperature, however, this would only be possible if you have a macroscopic body of varying degrees of freedom (dimensions). this is because heat is one way of transmitting energy from one macroscopic system to another.

 

[vanhees71]

It's a bit hard to imagine being a quantum particle, let alone how it would feel to be one, but indeed "heat" is just a form of intrinsic energy of the constituents of matter. For an ideal gas, consisting of a lot of particles which rarely interact by hard collisions with each other, it's indeed the kinetic energy. So as such a particle, you'd most of the time travel in straight lines from time to time hitting another particle, which changes your momentum and kinetic energy due to the bump. Of course, in each collision the conservation laws are fulfilled. After bumping into other particles a lot of times, you'll on the average gain as much energy and momentum as you loose, i.e., on average you get into a stationary state with all the other particles, and this "equilibrium state" is described (among other thermodynamic quantitities) by the temperature of the system. The mean energy of a monatomic gas particle is given by
$$\langle E_{\text{kin}} \rangle=\frac{3}{2} k_{\text{B}} T,$$
where $T$ is the absolute temperature (measured in Kelvin in the SI units), and $k_{\text{B}}$ is Boltzmann's constant, which is more or less a conversion factor of units.

 

[ZapperZ]

Hello! First post here so go easy on me. I am a Physics enthusiast, but I fear I am a layperson when it comes to the field. Most of what I know comes from low level college classes and the youtube channel PBS Spacetime.

I have a question that might be a ridiculous one. But here goes. (Go easy on me).

I keep reading and seeing in youtube vids that temperature is the measure of kinetic energy of particles in motion. So my question is if you could magically shrink yourself down to the size of a proton (or even smaller to the size of an electron) and touch one of those particles, would it feel warm? i.e. If temperature is simply how fast the particles are moving, do the particles themselves exist without temperature? Am I thinking about it all wrong? I'm curious and want to know.

I suggest that before you start to "extrapolate" the scenario that you think you have understood all the way down to the scale of a proton, make sure that you have first understood the scenario that you are using.

In this case, you are using the classical thermodynamics definition of "temperature" and kinetic energy. However, you have NOT fully understood this correctly. For example, it appears that you are not aware that this is a statistical measure of MANY particles in motion, so that the kinetic energy in question is the AVERAGE kinetic energy of the gas particles. this means that within this statistical picture, it makes no sense to talk about the temperature of a single particle, because that is not how it is defined!

This is a valuable lesson to many new members to this forum, and especially to "layman". Before you attempt to use what you think you've understood into something, please try to establish that what you thought you knew or understood is actually correct and accurate in the first place! This is important because if your understanding is faulty to start with, then everything built on top of it is nonsense and does not have a valid and proper foundation.

In other words, before dreaming of running the sprints in the Olympics, be sure to first establish the fact that you have the ability to walk.

Zz.