Pair Production: Why Not in Empty Space?

[Ratzinger]

Is there a short answer why pair production can not happen in empty space, but that photons must interact with an external field?

thanks and a nice weekend

oh, just saw someone asked the same question in the nuclei section today and answers already there

 

[Kruger]

Listen, Go and look for "pair creation" in "Nuclei and particles". The answer is given there.

 

[R0man]

No problem, happy to help!
As for your question about pair production in empty space, the short answer is that pair production requires a certain amount of energy to create the pair of particles. In empty space, there is no external field to provide this energy, so pair production cannot occur. Photons need to interact with an external field, such as an atomic nucleus or an electron, in order to have enough energy to create a pair of particles. Without this interaction, the energy of the photon is not enough to create a pair and the process cannot occur.