bsa@ncoast.UUCP (Brandon Allbery) (07/30/85)
Expires: Quoted from <2900@topaz.ARPA> ["Re: FTL & Physics"], by Alfke.PASA@Xerox.ARPA... +--------------- | Photons (and anything else which travels at lightspeed) are massless. | You can multiply their mass by any gamma factor (the thing that goes | infinite at c) and it stays zero: thus, the formula still applies. | Interestingly enough, photons do have momentum, which varies with | wavelength, not speed. | | If we could get rid of ALL of a starship's mass, we could get it to go | at lightspeed very easily ... hmmm. Sounds like a great gimmick for a | space-opera. +--------------- It's been used. The Heechee drive ``gets rid of'' gravitational mass (see GATEWAY by Fred Pohl); and the Lensman books use an inertialess drive, which cancels out inertial mass. The question is, which is needed? Or is it both? --bsa -- Brandon Allbery, Unix Consultant -- 6504 Chestnut Road, Independence, OH 44131 decvax!cwruecmp!ncoast!bsa; ncoast!bsa@case.csnet; +1 216 524 1416; 74106,1032 ========================> Trekkies have Warped minds. <=======================
barry@ames.UUCP (Kenn Barry) (08/15/85)
Quoted from <2900@topaz.ARPA> ["Re: FTL & Physics"], by Alfke.PASA@Xerox.ARPA... +--------------- | Photons (and anything else which travels at lightspeed) are massless. | You can multiply their mass by any gamma factor (the thing that goes | infinite at c) and it stays zero: thus, the formula still applies. | Interestingly enough, photons do have momentum, which varies with | wavelength, not speed. | | If we could get rid of ALL of a starship's mass, we could get it to go | at lightspeed very easily ... hmmm. Sounds like a great gimmick for a | space-opera. +--------------- One of Dr. Robert Forward's "Far Out Physics" ideas is along these lines. First, you postulate anti-mass - not antimatter, but negative mass. Its gravity pushes, and when it's combined with regular mass, you get cancellation, nothing, no energy. Anyway, you take approximately equal hunks of mass and anti-mass. The mass is your spaceship, the anti-mass your "drive". Hook 'em together (how?) (shut up, kid!), and the thing's inertialess (or nearly, depending on how exactly you measure the mass and anti-mass), because the total mass of the system's 0. It immediately flies off in the direction of the mass-end of the system (the mass pulls the anti-mass, the anti-mass pushes the mass) at a velocity approximating light. Anybody seen any anti-mass lying around? :-) - From the Crow's Nest - Kenn Barry NASA-Ames Research Center Moffett Field, CA ------------------------------------------------------------------------------- USENET: {ihnp4,vortex,dual,nsc,hao,hplabs}!ames!barry
thau@h-sc1.UUCP (robert thau) (08/15/85)
> First, you postulate anti-mass - not antimatter, but negative > mass. Its gravity pushes, and when it's combined with regular mass, you > get cancellation, nothing, no energy. > Anyway, you take approximately equal hunks of mass and anti-mass. > The mass is your spaceship, the anti-mass your "drive". Hook 'em together > (how?) (shut up, kid!), and the thing's inertialess (or nearly, depending > on how exactly you measure the mass and anti-mass), because the total > mass of the system's 0. It immediately flies off in the direction of > the mass-end of the system (the mass pulls the anti-mass, the anti-mass > pushes the mass) at a velocity approximating light. > Anybody seen any anti-mass lying around? :-) > > - From the Crow's Nest - Kenn Barry One other thing; you need to find Newton's third law and convince him to go on a coffee break. ("The mass pulls the anti-mass, the anti-mass pushes the mass ..."). -- Robert Thau \ Keeper of the *FLAME* )) rst@tardis.ARPA ( ( h-sc1%thau@harvard.ARPA \\
crm@duke.UUCP (Charlie Martin) (08/19/85)
In article <535@h-sc1.UUCP> thau@h-sc1.UUCP (robert thau) writes: >> ... because the total >> mass of the system's 0. It immediately flies off in the direction of >> the mass-end of the system (the mass pulls the anti-mass, the anti-mass >> pushes the mass) at a velocity approximating light. >> Anybody seen any anti-mass lying around? :-) >> >> - From the Crow's Nest - Kenn Barry > >One other thing; you need to find Newton's third law and convince him >to go on a coffee break. ("The mass pulls the anti-mass, the anti-mass >pushes the mass ..."). No problem. Delta-momentum is zero, since total mass is zero; therefore no ``force'' is involved, since F = 0a == 0 for all a. What I don't follow is why it only goes about _c_. And what happens if your anti-mass is slightly *larger* than your mass (so sum mass for the system is < 0)? -- Charlie Martin (...mcnc!duke!crm)
draughn@iitcs.UUCP (Mark Draughn) (08/28/85)
In article <535@h-sc1.UUCP> thau@h-sc1.UUCP (robert thau) writes: >> First, you postulate anti-mass - not antimatter, but negative >> mass. Its gravity pushes, and when it's combined with regular mass, you >> get cancellation, nothing, no energy. >> Anyway, you take approximately equal hunks of mass and anti-mass. >> The mass is your spaceship, the anti-mass your "drive". Hook 'em together >> (how?) (shut up, kid!), and the thing's inertialess (or nearly, depending >> on how exactly you measure the mass and anti-mass), because the total >> mass of the system's 0. It immediately flies off in the direction of >> the mass-end of the system (the mass pulls the anti-mass, the anti-mass >> pushes the mass) at a velocity approximating light. >> Anybody seen any anti-mass lying around? :-) >> >> - From the Crow's Nest - Kenn Barry > >One other thing; you need to find Newton's third law and convince him >to go on a coffee break. ("The mass pulls the anti-mass, the anti-mass >pushes the mass ..."). No no no. It's massless, so we can make up all sorts of rubbish about it. (I know that light is massless and we have strict rules about it; but light is genuinely massless whereas this ship just looks massless.) Anyway, we have here the makings of a great SF story because we can have skillfully trained experts whose job it is to make sure that the mass and anti-mass balance. There would always be molecules subliming off into space, or departing shuttles, or just energy radiating away that would screw up the balance and our intrepid technicians would have to use the mass-converter to balance the load before the compensators overloaded. This would make a great space opera... -anonymous I'm hoping that people who want to flame me for wasting space with this drivel will be too lazy to look up at the heading for the path.