up Question: Is mass conserved in particle collisions?
An electron that is moving at 0.999 999 999 948 c is supposed to have a mass of 8.93×10^26 kg just before a collision, according to Einstein’s equation for a moving particle. This is the mass of about 98,000 electrons at rest. However, the result of the collisions that you gave in your answers of such an electron with an accelerated positron (98,000 positrons at rest) does not come even close to what it should be produced according to Einstein’s equation. The reaction that you listed, electron+positron yielding a tau and anti-tau particles, accounts only for the mass of about 7,200 electron masses at rest.
