As I understand, an object with mass cannot reach the speed of light because its (relativistic) mass increases "exponentially" as it approaches light speed.
So there is a relation between mass and speed. But if speed is a relative measurement (it depends on a point of reference) how does that affect the mass?
Is the mass also relative to a point of reference?
Or is there some absolute speed (wrt some fixed point) which affects the mass of an object?
What I have trouble to understand is... given these two facts (I hope I got the facts right):
- Light always moves at the same speed (independently of the inertial frame of reference)
- The speed of a mass object is relative to a frame of reference
then if an object is moving at 99.999% of light-speed for a given observer, what will a different observer see?
Will that other observer see the object moving at a different percentage of light speed?
(assuming the observers are moving at different speeds, of course)