By Alfie Alsop
The most frustrating thing about living in this generation, for me, is the fact we’re getting pretty good at spotting interesting things out there in space (potentially life-bearing exoplanets, for one) and yet we still haven’t set foot on anything further away than the moon. And we haven’t done that for far too long either. The trouble is two-fold, funding and technology, and as I’m not an economist or a politician I’m going to ignore funding for the most part.
What we need is faster than light travel, (FTL for short).
Anyone who’s seen five seconds of science fiction will be familiar with the concept, whether we want to call it hyperspace, slip-stream, stargates or warp-drive it doesn’t matter, the point is that if we want to get around the universe we need something that allows us to traverse the mind boggling distances between us and the next interesting thing. The trouble is that physics won’t let us go faster than light, or at least that’s what our current understanding of physics says. Relativity shows us that the faster an object is travelling, the more energy it requires to go even faster, until at a point infinitely close to the speed of light an infinite amount of energy is necessary for further acceleration. But, as Star Wars fans will know only too well, that never stopped the Millennium Falcon doing the Kessel Run in under 12 parsecs.
In normal space, we’re pretty certain that faster-than-light isn’t possible, as we just can’t generate the infinite energy that we’d need. But that leaves the question ‘what about abnormal space?’
Well, popular theory is that we could travel faster than light by distorting space-time itself around whatever vessel we’d like to move. Space-time isn’t just sci-fi jargon, it’s the way physicists consider space and time together in one co-ordinate system in order to make sense of the weird world of relativity. The Alcubierre warp drive is a theorised way of achieving FTL, and involves creating a wave in space time that a vessel could effectively surf along. Space-time is shortened in front of the vessel and stretched out behind it, which is more than a little bit mind bending but, as far as we know, the theory is mathematically sound. The only trouble is we’re not sure how to actually generate a space-time wave.
The other potential, and apparently feasible method, is… well, it’s wormholes…
Wormholes (also called Einstein-Rosen bridges, to sound more scientific and less fantastical) are hypothetically possible, popping out in solutions of the equations for general relativity, and work like tunnels through space-time, shortcuts between point A and B. There’s a much used trope in sci-fi with a sheet of paper. It gets folded and a pencil pushed through, it’s a fairly good illustration of the concept.
Unfortunately we’ve never seen any evidence for the existence of naturally occurring wormholes, and again, we’re not exactly sure how we’d even go about making one, and this isn’t Stargate so we can’t just dig a wormhole up in Egypt.
Both the Alcubierre drive and the creation of wormholes would require the generation of a negative mass field. Mass distorts space-time in a certain way (you might recognise it, we know it as gravity) and negative mass would simply create the inverse effect. In the Alcubierre warp-drive we would have a large positive mass field in front of the vessel, squashing space-time, and a large negative mass field behind the vessel, which would stretch space-time and thus creating the wave I mentioned. On the other hand, the creation of wormholes would require a huge mass at one point in the universe, and then a similarly huge negative mass at another point, so the two disturbances would meet in the middle like cosmic stalagmites and stalactites in space-time.
This is all well and good, and even having such hypothetically plausible theories is a great start, but then the pragmatists start raining on our parade. We’d need an inordinate amount of energy to generate these kind of fields, even if we knew how to generate negative mass. The best bet for generating enough energy would be matter-antimatter recombination, and even with the grandiose claims from NASA last year about an Alcubierre ship that would only require 750kg of antimatter to initiate the space-time wave, it’s still not feasible. At the moment it costs approximately $100 trillion to create just one gram of antimatter, I’ll leave the maths to you but cosmologist Sean Carroll estimated that it would take 40 years of the entire worlds global monetary output to afford this relatively small amount of warp-fuel. It’s hard enough to convince the world’s governments of the need for any amount of space funding; I’m not so sure they’d sign up to give away all available money for a generation, for a hypothesis.
Maybe one day we’ll be zipping about the heavens in our sleek warp-ships or bravely stepping through the event horizon of a wormhole, but if it happens it’s not going to be for a while yet. Don’t give up hope though, what we’ve learned about space and time in the last two centuries is astounding, one can only imagine what physics will look like in another two centuries – we might well be missing something that’s staring us in the face.
Or we can hope that some benevolent extraterrestrials decide that we can join them in galaxy hopping and teach us how, the likelihood is probably on par with building an FTL engine in our lifetimes.