throopw@rtp47.UUCP (Wayne Throop) (05/20/85)
In <1982@sdcrdcf.UUCP> Darrel VanBuer says > Cherenkov radiation results (i.e. light) when anything goes faster than the > speed of light in a medium. Of course this only happens when the medium is > "slower" than a vacuum (e.g. water at 75% of c) since the particle still > limited by c. > Darrel J. Van Buer, PhD I was under the impression that the "anything" had to be charged, IE, an FTL neutron would not produce Cherenkov radiation. If I'm wrong, can someone more up on particle physics mail me a contradiction? In <5608@utzoo.UUCP> Henry Spencer says > Sigh, I knew about Cerenkov radiation, and if I thought people would be > this picky [I know, I know, I've done it myself sometimes...] I would > have qualified all references to "speed of light" with "in a vacuum". > I thought it was reasonably clear from the original posting that the > question referred to spaceships, i.e. operations in a vacuum. Now, if > somebody can tell me whether an FTL starship would emit Cerenkov radiation > in a vacuum, *that* would be interesting. > Henry Spencer @ U of Toronto Zoology Now *there's* a more difficult question. Since a spaceship presumably contains some charged particles, if it went FTL (thru water for example) I expect it *would* emit Cherenkov radiation. This probably would be pretty hard to detect amidst the vaporization of the spaceship. :-) On the other hand, just how is the ship supposed to acheive FTL status (in a vacuum)? If it is "hyperspace" or "wormholes" or whatnot, I'd expect no FTL shockwave, since these ideas generally have to do with remaining STL with respect to some "higher space" and sidestepping the issue. If it uses the "correspondence tachyon" method (where every particle of the spaceship is replaced by a corresponding tachyon), I expect it *would* emit Cherenkov radiation, assuming that tachyons have charge. Isn't one of the methods used to search for tachyons to look for the Cherenkov radiation? Interestingly enough, assuming that a tachyon emits Cherenkov radiation, it would naturally decay to lower energy (that is, higher speed) states, accelerating to "infinite" speed. A convenient way to get your spaceship to hurry up. In any event, I'm performing the "public service" of adding net.physics to the newsgroups of this line of discussion. It seems more relevant to particle physics than orbital mechanics or near term space engineering. -- Wayne Throop at Data General, RTP, NC <the-known-world>!mcnc!rti-sel!rtp47!throopw
rl@ucsfcgl.UUCP (Robert Langridge%CGL) (05/23/85)
<-- A quick introduction to faster-than-light travel (by charged particles at least), and the use of the resultant electromagnetic equivalent of the sonic boom, is given on pages 58-60 of the June 1985 Scientific American. Bob Langridge rl@ucsfcgl (UUCP and ARPA)
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (05/23/85)
> Isn't one of the methods used to search for tachyons to look for the > Cherenkov radiation? Yes, and you may notice they haven't found any.