I'll be honest — this is not the post I wanted to write. When NASA released their new renders of a hypothetical future faster-than-light spaceship, I wanted to believe that such a craft was mere decades away from reality. Then I made the mistake of asking someone much smarter than me about it.
That much smarter someone is noted physicist Sean Carroll, a theoretical cosmologist specializing in dark energy and general relativity. He's the sort of guy who knows about this kind of faster-than-light travel and warp bubbles and all this sort of exciting stuff. He's a scientist immersed in this world, and as such he's not going to sugarcoat the reality of the universe as it's currently understood just because I want to join Starfleet.
So, when I asked him for his take on just how feasible this warp-drive ship is, here's how he responded:
The Alcubierre warp drive is a very interesting arena for thought experiments to try to better understand general relativity and quantum field theory, but it should give you zero hope for actually building a spaceship some day. Some of the many problems are discussed on Wikipedia:
In short, it requires negative energy densities, which can't be strictly disproven but are probably unrealistic; the total amount of energy is likely to be equivalent to the mass-energy of an astrophysical body; and the gravitational fields produced would likely rip any ship to shreds. My personal estimate of the likelihood we will ever be able to build a "warp drive" is much less than 1%. And the chances it will happen in the next hundred years I would put at less than 0.01%.
But they are very pretty pictures! Would look great in a movie.
Undaunted, I asked him if these assessments were taking into account the work that Harold White had done that dramatically reduced the energy requirements of the Alcubierre Drive. It looks like they weren't, which gave me some hope, until I read the rest of his response:
... note that "the mass-energy equivalent" of 700 kg (which I don't believe for a second, I suspect you need much more) essentially means you need 350 kg of antimatter to combine with 350 kg of matter. From here:
they note that the current cost of producing 1 gram of antimatter is about $100 trillion. But, with completely unsupported optimistic estimates, you might get that down to $10 billion per gram. So, with the most wild-eyed pie-in-the-sky estimates, fuel alone will cost you $3.5 quadrillion — roughly the entire economic output of the world for forty years. Good luck with the Kickstarter!
Okay. So maybe we all are getting a little more worked up than is merited over these spaceship renders. Forty years of global economic output is pretty expensive, even if I can talk them down, say, 10% or so.
This blast of cruel, scientific reality did depress me for a bit, until I realized something. Something that Sean had not actually said. For being as pessimistic and coldly rational as he was — and as his role as a scientist all but demands him to be — it's worth noting that he never actually said that this sort of faster-than-light travel is impossible.
As far as I know, this may be the first point in history where that statement is true: a coldly scientific assessment of a faster-than-light spaceship did not meet with immediate dismissal as an impossibility. Sure, he pegged the odds of it happening at under 1%, but that's 100% more possibility than we've ever had before.
And while I suspect that this is the exact opposite take-away that Sean was going for, I'm actually strangely encouraged about the future (admittedly very very long-term) of a project like this. I respect the hell out of Sean Carroll, and I have no reason to believe his assessments are anything but sound. That's why the fact that buried in all those reasons why this ship is currently impractical, that little nugget that suggests it's theoretically possible is so tantalizing.
Sure, we can't do it now, but if humanity has proven anything it's that given enough time, we tend to make impossible-seeming things real. Hand a Victorian engineer a shiny disc and tell him that on that disc, stored in tiny pits and peaks read with a beam of coherent light, are hundreds of songs and pictures and books, and he'll look at you like you're insane. Then tell him how we've already gone beyond that technology and people will throw away those discs like they were spoiled mutton.
So, despite Sean's very reasonable and rational criticisms, I hope NASA continues their research into Alcubierre/White drives. I hope they take these issues into account, think about them, work, imagine, develop, design, and eventually, whenever that is, figure out a solution.
Sean's probably correct, at least right now. But I'm still hopeful for the day he may be wrong. At least about this.