What is the significance of pair production to special relativity?

Answer 1

Pair production is the creation of an elementary particle and its analog, or antiparticle, by a photon or an uncharged boson. It's significance to special relativity could be described by saying that it is a consequence of special relativety. This classical quantum mechanical process is the creation of matter from energy according to the basic equivalence theorem, E = mc2. That said, let's look at what is arbuably one of the most "common" cases - the creation of an electron-positron pair from a high energy photon. If a photon of sufficient energy slashes through the space near an atomic nucleus, the energy (or some of it) will be converted into mass. It takes a lot of energy to make a little mass, just as converting just a tiny amount of mass into energy makes a lot of energy. In the case of the electron and the positron, the latter being an anti-electron or antimatter, the minimum energy needed to create the pair of particles is 1.022 MeV (million electron volts). This is equivalent to the rest mass of a pair of electrons. We're creating two particles, are we not? If a "hot" gamma ray (meaning a high energy one) of 1 MeV flashes by a nucleus, no electron-positron pair will appear because the energy threshold has not been met. Special relatively actually speaks to the lack of any "immune" inertial frame when considering the speed of light and how its speed is measured. Translation: the speed of light is a constant, no matter what your frame of reference. But pair production will follow quantum mechanical principles meaning a given amount of energy will be converted to mass per the mass-equivalence equation, and also that charge, spin and other quantum mechanical characteristics, the so-called quantum numbers, will be conserved.