Temperature in a vacuum?

Question

Can there be temperature in a vacuum?, since there is no air?

If so, whats the temp?

Please advise

Thank you

Answer 1

It actually depends on the temperature of whatever is surrounding the vacuum. Heat transfer occurs by conduction, convection, and radiation. In a vacuum you eliminate conduction and convection, just leaving radiation. Heat transfer will occur between the outside space and the vacuum but at a much slower rate then the other forms of heat transfer. So to sum up my answer...it will eventually develop an equilibrium with what ever temperature surrounds the vacuum.

Answer 2

Yes, there is temperature in a vacuum.  Temperature is defined by thermal distribution of a system.  In a vacuum, you can (and do) still have photons flying around.  With higher the temperature, there will be more photons and each will have a higher average energy.  So to measure the temperature, you would look at the distribution of photons and photon energies, and then you would compare those distributions to a thermal distribution (which is a well defined mathematical function, like a gaussian distribution) to determine the temperature.

If you were to then add gas to the system, you would measure the temperature by looking at photon distributions and the velocity distribution of the gas particles, and compare them, again, to a thermal distribution.  

If a system can have particles in different energy states, it can have a temperature.  And a vacuum can have photons, so it can have a temperature.  

Answer 3

temperature of vacuum is 2 kelvin.