Question

can you measure a one-atom temperature? does subatomic particles have a role in temperature?

Answer 1

I heard that when smashing particles at particle accelerators, particles reach very high temperatures, does this temperature refer to the average kinetic energy of all the subatomic particles that are produced during the collision?

Answer 2

These, "very high temperatures" refer to the kinetic energy in the form of heat produced as the particles collide with one another. At such high velocities these collisions can generate temperatures of about 10 Trillion degrees.

Answer 3

but if you had only one hydrogen atom colliding another at near light-speed, wouldn't they break into smaller particles whose kinetic energy summed the energy of these initial hydrogen atoms? The definition of temperature is vibration of submicroscopic particles where vibration is refering to the average kinetic energy of these particles, having only individual atoms, it makes no sense measuring the average of one particle kinetic energy or the vibration of it, it would be like just measuring its momentum. I understand that temperature is a measure for groups not individuals.

Answer 4

Temperature is just the measure of energy in the system, and is just a convenient way of expressing the units of temperature. While we are used to the idea of kinetic energy being associated with temperature in classical gases ideal gases, in non-ideal gases, the internal degrees of freedoms due to inter-particle interactions contribute to the total energy of the system and hence to the "temperature" of teh system.

One example is this. In solid state physics, a metal can be thought of as a plasma of electrons surrounding immobile ionic cores. There is a property known as the Fermi-energy of the electrons, and associated with this energy there is a Fermi temperature of the electrons. At room temperature the metal will have the temperature of the surroundings (about 300 K), but the fermi temperature of the electrons will be much much much higher. For example gold has a fermi energy of about 5.5eV meaning that its fermi temperature will be about 64,000 K (about 10 times hotter than the surface of the sun). So when you here in particle physics of huge temperatures bear in mind that it is only a convenient way of expressing energies, especially to the public who wouldn't know what an electron volt is.