Sunday, 26 February 2012

Sci-fi: the speed of light problem

Sci-fi can vary from almost fantasy with lasers instead of magic to being very realistic indeed. However, the speed of light does pose a problem.

Essentially, travelling that fast is reckoned impossible because it's the maximum speed anything can travel. (And that’s disregarding the dilation of time, as described by Einstein and sung about by Brian May in ’39).

This matters because the galaxy is so widely spread out that travelling almost anywhere beyond the solar system requires a very fast system of travel. Voyager was launched in 1977, and only reached the edge of the solar system last year (

So, there are a few options:

Ignore science: this is the simplest method of resolving the problem. Just use warp speed or hyperspace or whatever you want to call it, and don’t bother explaining how it works. The only potential problem is if you’re trying to make your sci-fi story as realistic (scientifically) as possible.

Alien technology: pretty similar to the above, but with a crucial difference. A system of gates (as used in the very enjoyable Stargate SG-1 series), for example, enables travel over huge distances but does not allow the human race to have a similar tech level in other areas. So, you get the travel options but can keep everything else more realistic and lower tech.

Don’t go that far: keeping the human race confined to the solar system, and perhaps one or two of the nearest stars reached by sleeper ships, can work perfectly well. Mining on other planets and moons (or the asteroid belt), wars over territory and so forth doesn’t really need a far flung empire.

The actual decision made doesn’t especially matter provided it doesn’t jar with the rest of the universe the writer’s created. Maximum realism of 27th century firearms coupled with a magic box with Light Speed Engine written on it would rather break immersion.

I tend not to read as much sci-fi as fantasy. The last books I read were Toby Frost’s excellent Space Captain Smith series. This is probably because I prefer history to science, and find the general fantasy worlds (medieval England, Rome, Byzantium, Middle-Earth etc) more to my taste. That said, I think I might try hunting down some new sci-fi.



  1. There is another option - pay very close attention indeed to what science is saying and exploit the loopholes whilst slipping past the problems. Hard science fiction authors are very fond of the Alcubierre Drive for instance...

    Thanks for mentioning Voyager BTW - my degree thesis many years ago was partly on the heliopause and I've been watching Voyagers progress with increasing interest.

    And as for '39 - I've listened to that song literally dozens of times over the years and never once realised it was about time dilation! I've know for years of course that Brian May was/is (he completed his PhD only a couple of years ago) an astrophysicist, but I never realised he'd written a song about it untilnow...

  2. I must admit I'd never heard of the Alcubierre Drive. It sounds a little beyond me, but quite intriguing.

    Is the heliopause the region between the far edge of the solar system and outer space? I do wonder how long we'll keep getting info from Voyager (and hope that it doesn't end up like the first Star Trek film).

    Hehe, I must admit I only knew about the time dilation because I checked to see whether the 'milky sea' meant the galaxy, and read up a little on the meaning of the song and the theory.

    There's a nice balance between May and Mercury. Not sure if May wrote many other science-based songs, but Mercury wrote loads of fantasy-inspired ones. Ogre Battle, Fairy Feller's Master Stroke and March of the Black Queen spring to mind.

  3. Very roughly,if you can imagine the solar wind blowing a bubble in the interstellar medium then the heliopause is the region where the pressure of the solar wind drops to the point that it can no longer push back the interstellar medium. There's a turbulent zone before the heliopause where the solar wind slows down and heats up as it collides with the interstellar medium, and it's this zone the Voyagers are travelling through at the moment. The crossing of the heliopause should be indicated by a sharp drop in the temperature of the charged particles it's detecting as it leaves the turbulent area, and this is predicted to happen in the next couple of years, so long as the Voyagers hold out (they're years beyond their design life).

    It's regarded as the boundary of the solar system because it's the point at which the solar wind gives way to the interstellar medium, but of course there's stuff orbiting the sun much further out, up to a couple of light years in the case of the Oort Cloud.