(spaceships) rocket (super)science

[whswhs]

Originally Posted by johndallman

Smith did not go into details of just how this allowed travelling faster than light, but it certainly did in the Lensman series of space-operas.

As I understood it, the argument was that what stopped you from reaching the speed of light was that as you accelerated, your effective mass increased without limit, so that no amount of thrust could give you sufficient acceleration. Smith seems to have thought that if you didn't have mass (which was the effective result of inertialessness), you could just go on accelerating right past c. He doesn't seem to have thought about the fact that particles with rest mass zero such as photons travel at exactly c and cannot be further accelerated . . .

Technically, what was limiting your superluminal speed was that as you pushed forward, whenever you hit a particle, no matter how tiny, it stopped you dead. But your continuing thrust would then push you forward, accelerating the particle sideways. So this went on until your thrust exactly equalled the force you needed to shove aside all the particles in the local medium. Effectively you were experiencing the interstellar or intergalactic vacuum as a very tenuous fluid and overcoming its resistance. (It's not as simple as that, either, but that's a different story.)