4 ms·
Curious, can this process be reversed? Also, is momentum conserved, then if it is wouldn't the positron and electron be ejecting at the speed of light (and wou
by pretadank 5y ago
Curious, can this process be reversed? Also, is momentum conserved, then if it is wouldn't the positron and electron be ejecting at the speed of light (and wouldn't that violate the principle that matter cannot reach the speed of light)? If not what is slowing them down / where is the energy going? Could this be theoretically a way to power something? Either by the ricochet of the particles off something, or by using them to energize something?
- whatshisface 5y agoAll quantum-mechanical processes can be reversed. In fact, this process is actually a lot more common in the other direction; a positron and an electron making a pair of photons is matter-antimatter annihilation and it happens all the time. This is because a couple photons are thermodynamically preferred over an electron-positron pair at room temperature. It's kind of like how allotropes of solids will form and reform as you change the heat and pressure.
- tsimionescu 5y agoMomentum is mass times velocity. Momentum is conserved, but you're going from (probably) mass-less photons moving at c to mass-ive electrons/positrons moving at <c.
- drdeca 5y agowhen you say mass times velocity, I take it you mean relativistic mass? I assume you know all the following, and I'm just saying it to explain my reasoning for the above / to elaborate for other readers. One can certainly pick a frame of reference such that the total momentum of the electron and positron afterwards is non-zero, and therefore the total momentum of the photons beforehand (in that reference frame) will also be non-zero , despite photons having (or, believed to have, but I believe it also) 0 rest mass.