Thread: mass and the speed of light question

Why is it that something gets heavier when it moves faster i.e. near the speed of light at least according to Einstien.

Originally Posted by Topalk

Why is it that something gets heavier when it moves faster i.e. near the speed of light at least according to Einstien.

It is a consequence of special relativity which is a consequence of the fact that the speed of light does not vary with the speed of the source.

Read up on special relativity.

As you get close to the speed of light, doubling the energy applied does not double the speed. You approach a limiting value, c , and even if you add large amounts of energy, you approach but never quite reach c. Now since mass/energy cannot be created/destroyed only changed from one to the other, all this extra energy which has no, or very little, effect on speed is changed to mass.