: : : One could nullify gravity with particles that possess negative mass. Such particles are predicted by String Theory. They are called tachyons. Actually, to be more precise they possess negative mass squared, but that should not matter. The real problem though is that such particles travel faster than the speed of light, like the virtual gravitons discussed earlier in this forum. If you could detect them and then capture them in sufficient quantity, then you could nullify gravity with an anti-gravity vest.

: : Yes, I've heard of tachyon particles. Isn't it true that as they lose energy they speed up, and as they gain energy they slow down and approach the speed of light? Do you know where I could go to learn more about String Theory? Any help would be much appreciated.

: : Thanks,

: : Mav

: yanniru: : The latest on-line papers on string theory may be found at http://jhep.sissa.it/ These include much discussion of tachyons. If you are not a string theorist, do not be frustrated by the language they use. Even ordinary physicists cannot understand it. A search for string theory will yield more readable discussions. : Tachyons in string theory are found as the lowest mode of a closed string in 26-D. The next higher modes, the first excitation level, are a massless scalar and a massless dilaton. All higher modes have positive mass. So it seems that the energy of tachyons in string theory is fixed.