Reference: Essays on Substance
Relativistic Mass
Many people believe, “As the speed of matter approaches the speed of light its mass increases to infinity, and therefore it is impossible to make matter travel faster than light.” Such people misinterpret Einstein’s theory of Relativity. This belief erroneously considers the external force required to increase the velocity of a particle as its “additional mass.”
In fact, a matter particle, as an isolated system, will decrease in its mass and inertia to increase in velocity. If external force is involved, then more force will be required to push a particle that offers less inertia. For example, a photon has no mass or inertia; therefore, it becomes impossible to accelerate it even with an infinite amount of push.
Einstein never derived the expression for relativistic mass himself and privately disapproved of it. By 1948, he had come to denounce the use of relativistic mass as it was being applied in special relativity.
The fact is that matter is very limited in its velocity before it looses its identity as matter and converts into a quanta of energy to have greater speed.
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