Recently someone asked “how can a rocket work in the vacuum of space where there is nothing to push against?” The answer given was “the rocket it pushing away from it’s own exhaust.” Sounds reasonable but doesn’t seem quite right. (Isn’t there a simple Physics law that explains this?)

I was wondering if a nuclear blast(s) could be set off at a certain distance from the asteroid if the effect would be to push the asteroid off its trajectory without turning it into rubble.

Now, in line with the “rocket in a vacuum” question, how would the energy of a nuclear blast be transmitted through space and act upon the asteroid? I imagine the pressure produced with conventional explosives is caused by expanding gases. The damage done buy a nuke appears to be done by a shock wave traveling though air. What forms of energy are released in a nuclear blast beside heat, light and the kinetic energy of the bomb material and how would they travel through space?