Thursday, November 29, 2012

A Workable Warp Drive

The idea came to White while he was considering a rather remarkable equation formulated by physicist Miguel Alcubierre. In his 1994 paper titled, "The Warp Drive: Hyper-Fast Travel Within General Relativity," Alcubierre suggested a mechanism by which space-time could be "warped" both in front of and behind a spacecraft.

Michio Kaku dubbed Alcubierre's notion a "passport to the universe." It takes advantage of a quirk in the cosmological code that allows for the expansion and contraction of space-time, and could allow for hyper-fast travel between interstellar destinations. Essentially, the empty space behind a starship would be made to expand rapidly, pushing the craft in a forward direction — passengers would perceive it as movement despite the complete lack of acceleration.
White speculates that such a drive could result in "speeds" that could take a spacecraft to Alpha Centauri in a mere two weeks — even though the system is 4.3 light-years away.

"Remember, nothing locally exceeds the speed of light, but space can expand and contract at any speed," White told io9.
[In fact, current theories on the Big Bang and the early universe require space to have expanded much faster than light speed following the Big Bang]. "However, space-time is really stiff, so to create the expansion and contraction effect in a useful manner in order for us to reach interstellar destinations in reasonable time periods would require a lot of energy."
And indeed, early assessments published in the ensuing scientific literature suggested horrific amounts of energy — basically equal to the mass-energy of the planet Jupiter (what is 1.9 × 1027 kilograms or 317 Earth masses). As a result, the idea was brushed aside as being far too impractical. Even though nature allowed for a warp drive, it looked like we would never be able to build one ourselves.
"However," said White, "based on the analysis I did the last 18 months, there may be hope." The key, says White, may be in altering the geometry of the warp drive itself.
... "I suddenly realized that if you made the thickness of the negative vacuum energy ring larger — like shifting from a belt shape to a donut shape — and oscillate the warp bubble, you can greatly reduce the energy required — perhaps making the idea plausible." White had adjusted the shape of Alcubierre's ring which surrounded the spheroid from something that was a flat halo to something that was thicker and curvier.

... And in fact, White says that the warp drive could be powered by a mass that's even less than that of the Voyager 1 spacecraft.
That's a significant change in calculations to say the least. The reduction in mass from a Jupiter-sized planet to an object that weighs a mere 1,600 pounds has completely reset White's sense of plausibility — and NASA's.
Read the whole thing. See also this article at the Atlantic.

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