Planetary Resources: thar's gold in them thar space rocks

COUNT ME IN! As one of the people receiving the cheques - I'm perfectly willing to act as their special economic advisor at appropriate day rates.

Huh, I missed this thread the first time around. One of the things people miss out on is not considering real economic value. There's no margin in building stuff in space as long as nobody cares about stuff up in space! McCullough got at this, much to Gus's annoyance I sense.

I guess maybe this is the thread for wacky sciency stuff. So heres something that just cropped up on my facebook feed: NASA is building a warp drive.

Spoiler alert: they're not. What actually happened is that some NASA brainiac published a paper describing potential efficiency gains for the Alcubierre metric, which is a hypothetical means of interstellar transport that works by folding spacetime. His efficiency gains bring it from requiring all the energy in the universe to merely most of the energy on the planet. So that's nice.

The trick is that the Alcubierre metric assumes the existence of negative energy density. AKA negative mass. AKA exotic matter. Which - cool as it would be* - doesn't exist. Nor is there any reason for it to exist, there's no hint of it empirically and nothing in our physics suggests it might exists. It's mostly a cool thought experiment. "What if matter had negative mass...." So yeah, NASA is not building a warp drive, nor will they be building a warp drive. Sadly. :(



* If you grant exotic matter, you're almost certainly going to grant wormholes. Wormholes are acknowledged as quantum phenomenon; one of the things that keeps them from being a deal is that they're totally unstable at macroscopic scales. Via some wacky differential equations that I'm not even going to begin to try understanding, apparently exotic matter would allow you to expand a wormhole and keep it stable. So yeah, if you grant the exotic matter, then you grant wormholes. So who needs a warp drive now?

What is that, a 10^23 cost reduction? He deserves a nobel prize.

More seriously, I can never quite tease apart the frame of reference problems / perceived speed of light inherent in these research areas.

Yeah getting your head around reference frames is a bitch. The trick behind Alcubierre (and wormholes, iirc) is that since nobody is actually accelerated past the speed of light, there's no reference frame issues.

The theoretical cost reduction is sexy if it exists; I found the actual paper and it doesn't mention anything like that. 1600 tons of mass energy is about the energy output of the US in a year which is obviously doable, though it (tellingly) doesn't give you a rate. 1600 tons of mass energy for.... what? How far does that get you?

More seriously: the exotic matter thing really is a deal breaker. While some interpretations of the Casimir effect imply negative energy density, IMO it's one of those things that's just a cool what-if concept with no physical backing. Obviously I say that as a wannabe economist who's got no background in physics, so take it or leave it. :)

Another fun implication of granting exotic matter: time travel. By relativistically accelerating one wormhole terminus, you could create a time bridge. This won't let you go back in time from when the wormhole was created, but by relativistically accelerating interface B with respect to A, you'd end up with B in the future relative to A, so time travel back and forth was possible. Or maybe. Some interpretations involve this sort of playfulness annihilating the wormhole.