What it is in Einstein's theory of relativity that rules out travel faster than the speed of light?

It is Dr. Albert Einstein's special theory of relativity that says that a body cannot have a speed greater than that of the speed of light—i.e 2.99392.458 kilometres per second. Einstein's reason- ing is based upon the thought experiment in which equations (i.e. laws of physics) break down. Assume that an astro-naut's rocket travels by us at speed of faster than the fight. A flashlight a beam he sends forward from the back of his rocket would never catch uprth the front of the rocket. This is not what another as-tronaut in his oven rocket having lesser uniform mo- 'N :ion 'HOU Id see. Since the effects of the law of physics should look the same to each and every observer in uniform motion. it is impossible for the first astronaut to beat the speed of light, which is precise:y 299392.458 kilometres per second. There is also a physical reason why a body cannot be given a speed greater that of the light A body's atoms are electrical in nature and the mass of a charged particle increases with increase in speed. The increase is imper-ceptible until the speed nears that of the fight, when the mass begins to rise rapidly. In consequence, the body would require the application of a continualiy increasing force to accelerate its motion, and as the speed approached that of fight, the mass and the force would approach infinity—which is an impossibility.