Yes Channel Hopper, fair enough, I can be really irritating, and won't try to deny it! However, "fact is facts". So, although I don't want to get into a nasty argument - causing bad feelings all round - it remains true that:
1) Cavorite is physically imposssible, for the reasons I gave (also, see the above links, and many others).
2) It was suggested by HG Wells, not Jules Verne! (although, Verne's "rocket gun" would also have been impracticable, becasue it would instantly have killed his vehicle's occupants).
3) If Felber is correct (!), then for his effect to "kick in", you still need to reach roughly 60% of lightspeed first. Don't forget, as mass accelerates, it increases, a "runaway effect" effectively stopping you doing that.
(see:
www.centauri-dreams.org/?p=541 ).
4) As Felber himself - and the other commentators - say, there's no magic here (Cavorite is still impossible!), the necessary energy being "donated" by the "accelerator" mass. It's a bit like the more familiar "gravity well slingshot" manoever, much mentioned in Arthur Clarke's books, and used in real life for outer solar system probes.
5) You'd need a "convenient nearby mass" (as Felber says, where are they?), and then to slow down a "reverse effect" the other end (which Felber doesn't predict!).
6) The most interesting outcome is, it's testable in particle accelerators:
(see
http://www.nasaspaceflight.com/content/?id=4292 ).
In which case, since 99% lightspeed is often reached, why haven't we already seen it?
