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What would happen if a object travelling at 99.9% the speed of light managed to produce a sizable explosion in back of itself, (of course shielding itself from the blast, using the blast as a means of propulsion) As far as I know the blast would have to add to the velocity of the object and thus it would presumably go faster than the speed of light, even though the particles in the object would theoretically not be able to go this fast, the explosion should force the object faster, regardless? correct?

No, your conjecture is not correct. In relativity, it is very hard to increase velocity of objects that are already moving very fast. This is what prevents any object from moving faster than light if it started with a slower speed.

jasjeet s bagla

The reason the object approaches c (the speed of light) its effective mass increases so it takes more force to accelerate it. Theoretically, any object with non-zero rest mass would have infinite mass at velocity = c. Thus, nothing can exceed c.

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