I recently read the "His Dark Materials" trilogy by Philip Pullman, a highly philosophical "young adult" fantasy series. The first book, called "The Golden Compass" in the USA, was just made into a movie which I hope to see on my home screen soon. The movie was not a huge success and there are no plans to make the other two books into films, but I would rather see it through the lens of my own imagination anyway.

In the trilogy, for those who haven't heard of it, the story is about a young lady named Lyra, who lives in an alternate world to ours. She finds a way to travel from one parallel universe to another, finding friends and foes along the way and helping to save the multi-universe from…something, it wasn't clear to me just what that was.

Note how easily I toss off the idea of "multiple universes" or "parallel worlds." I shouldn't be so easy about it. The idea of multiple universes was proposed decades ago by physicist Hugh Everett, whose ideas were rejected by the physics leaders of the day. Now, it is common to read about it in the popular science media, and it has become, if not mainstream, certainly part of the modern theoretical scene.

The only problem is that these parallel universes, even if they exist, can't be found or proved to exist, at least with current technology. There is a kind of wishful hope that the grand and glorious new Large Hadron Collider just starting up at CERN near Geneva will somehow reveal these parallel worlds. The physicists there are hoping that perhaps a particle squirted out from a high-energy collision will escape into one of these other worlds, to be counted out only by its absence. This has never been recorded from any other atom smasher, but they are hopeful with this one.

Even if a particle or two really did find its way into another universe, there's no way that anything as large as a human being could make the trip. And there's also no idea of what that alternate world might be like. Some versions of string theory propose that there are an almost infinite, or even really infinite number of these worlds, each one having different properties and physical laws. The alternate worlds that the Pullman characters pass through all support human life, otherwise there wouldn't be much of a story.

But the differences between alternate worlds may be more radical. I have not heard anyone talk about this, but what if time itself went slower or faster in these worlds? Relativity proves that time goes slower as the observer goes faster, but what if a whole alternate universe was relativistic? In the Pullman books, time seems to go at the same rate in all of the worlds (which makes the story possible), but there's no reason why it should. There are myths about a person taken into the world of the elves or fairies, who spends what he considers to be two weeks, and yet when he comes back into his own world, twenty years or more have elapsed. To me this seems like a mythic version of relativity, anticipating the famous "twin paradox" where one twin makes a space voyage almost at the speed of light and comes back to an Earth where his other twin is old or long gone.

So if a particle escapes into another universe (or dimension — how different are they?) how do we know that it won't travel into another time zone where it, and things made from it, live forever by our limited standards? Or perhaps the opposite is true. Something, or someone, could stumble into a parallel world where time goes far faster than ours, and he might come back to our world twenty years older when for us, only a second has passed. And somewhere "out there" in the endless variety of dimensions, there may be some where time simply doesn't exist, a universe that is one immense black hole. That is best left for dark fantasy.

Posted at 3:16 am | link