Thursday, May 19, 2011

They Bended the Light

The trials and traumas of being a science-fiction writer? There are plenty, let me tell you. How do you reconcile the following, for instance: Newton believed that light was made of tiny little particles with mass—but that gravity did not affect them. But Einstein believed they had no mass, but gravity pulled them nevertheless!

Fortunately SF-writers have a kind of license, like court jesters used to have. The latter could speak truth to power and still stay out of dungeons. In our more commercial times, SF-writers don’t aspire to publication in peer-reviewed journals. They worry more when Marvel Comics frowns.

My problems have been with gravity bending light. A writer needs light to fly in straight lines to produce decent space tales. If massive things bend light, even if ever so slightly, and if dark matter is as prevalent as science tells me that it is, how do I know that a star I see at night is actually where it is? It might be somewhere quite different, hiding at the tail end of a million-light-year-zigzag course and not be rotating where it seems to. There may in fact be a huge body entirely obscuring the star I see, but the light from it has managed, by Einsteinian assists, to curl around this obstruction. To illustrate this hide and seek, I provide a graphic I made myself, but the inspiration for it was Jeffrey Reynolds’ here.

The way science explains the dilemma is to say that photons “follow the geodesic” and their mass-less nature does not guarantee straight paths. But what does such phraseology mean? By “geodesic” scientists refer to the curvature of space, more correctly of space-time. It isn’t as if gravity affects a mass-less particle. No. It is that great masses cause space-time to curve. And once that space-time has curved, light follows it. Self-evident, isn’t it? Or is it? Well, let me not try to explain that to a science-fiction reader. Space-time exists (in the sense of really being there) largely as a mathematical conception. And if it exists in reality, there is no actual physical description of how this “whatever” tangibly influences things we can actually see (like light) or touch and feel (like matter). It’s a muddle. I can fill whole walks just pondering how space-time knows to straighten itself out again after a big bad ball has caused it to curve. Or is it just displaced? Like water by a sinking ball of lead? But if so, it must be something. Is there a Theory of the Elasticity and Fluidity of Space-Time? I wonder.

The trigger for these thoughts? Well, in today’s paper I came across a front page story on a discovery, by Takahiro Sumi and team, at the Osaka University, that hundreds of billions of gigantic planets, gas giants like Jupiter, clutter-up our galaxy, none of which is associated with a solar system—orphans, in other words. There are supposed to be twice as many of these orphans as there are suns in the Milky Way—thus around 400 billion of them. Okay. But the interesting thing, for me, is that this discovery is based not on actually seeing these giants in their enormous numbers but by a method called microlensing. And what is microlensing based on? Why, the ability of big heavy objects to bend light. Now we have yet another marvel to add to black holes (that relentlessly suck everything in but, no surprise, sometimes let things escape), the curvature of the universe into a self-contained sphere (what is outside that sphere?), the blackness of space (why isn’t space brilliantly lit when light cannot escape the sphere?), the perpetual expansion of the universe (into what? the as yet undiscovered Cosmic Container?), the big bang before which there was, what? nothing? And finally the energy-death of reality when every last hydrogen has been burned up? Lordy. I sometimes think that treating science as if it were immune to the current philosophical and cultural meltdown is actually a mistake. But not a mistake we have to make in fiction. Those 400 billion lonesome giants might one of these days come in quite handy. And soon there might even be a country-song about them…

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