3 ms·
Your comment seems like it would rule out a photon rocket , which proves too much. I think the resolution is that the faster you go, the heavier you are and the
by murbard2 6y ago
Your comment seems like it would rule out a photon rocket , which proves too much. I think the resolution is that the faster you go, the heavier you are and the more thrust you need to increase your dv.
- contravariant 6y agoA photon rocket still has a preferred reference frame where the total momentum is 0. Don't forget that photons still have momentum, even if they don't have mass.
- DennisP 6y agoSo you can calculate, for a given thrust/energy ratio, what velocity you have to exceed to get more energy out than you put in. For relativistic effects to make enough difference to matter, that velocity would have to be pretty close to c. That translates to an extremely low thrust. (I've been told that for a photon rocket, the threshold velocity is c, implying that a reactionless drive won't violate conservation of energy as long as it's no better than a photon rocket. I haven't done that math myself though.)