Charlie Stross did, in my opinion, a better analysis ( https://www.antipope.org/charlie/blog-static/2007/06/the_high_frontier_redux.html https://www.antipope.or

Charlie Stross did, in my opinion, a better analysis ( https://www.antipope.org/charlie/blog-static/2007/06/the_high_frontier_redux.html https://www.antipope.org/charlie/blog-static/2007/06/the_hig... , discussed on HN at the time at https://news.ycombinator.com/item?id=2639456 https://news.ycombinator.com/item?id=2639456 ) where his math seems to show that even lossless matter to energy conversion with lossless[1] conversion of that energy to thrust wouldn't make interstellar travel feasible. [1] The word "lossless" alone ought to raise eyebrows since, as far as I understand it, FTL travel is far more plausible than circumventing the laws of thermodynamics.