Gravitas

I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not frame hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.

     [Isaac Newton, Mathematical Principles of Natural Philosophy, 1713]

We really know very little about matter, but we’re not quite as continent as Newton was when it comes to framing hypotheses. Descriptions of behavior, however precisely measurable, do not explain what really happens. Two bodies will exert a force on one another based on their masses and distance, but why that force is operating is not thereby explained. Quantum physics offers the notion that the force of gravity is mediated by a mass-less particle called the graviton (a hypothetical particle). In Relativity, Einstein offered as his hypothesis that mass causes time and space, the two combined in a single continuum called spacetime, to bend or to deform in some way thus creating a groove or slope in what (presumably) is an otherwise unchanging “environment.” This deformation is then used to explain gravitational effects. But what exactly are space and time? For Newton they were absolute and entirely unchangeable let’s call them realities; mass could not change either one or the other. For Immanuel Kant they were, at the same time, immaterial and thus insubstantial, in the human mind as a priori organizing principles enabling us to understand sensory experience and therefore ideas. But because they were linked to sensory experience, they were also empirically real. In other words we don’t really have an explanation—hence framing no hypotheses is indicated—at least in “experimental philosophy.”

Space and time are inherently involved in any kind of explanation of gravity, be it by gravitons or spacetime deformations—or invisible, intangible dark matter used by most astronomers to explain gravitational anomalies in star rotations around galaxies far away. That hypothesis, incidentally, has the small problem of increasing the total mass of the universe by huge gob. Visible matter is supposedly 4 and dark matter is 96 percent of the universe. Now supposing we did detect a graviton finally. Where would that leave us? It would leave us wondering what makes gravitons detach from one kind of mass to rush at the speed of light, and presumably no faster, to another essentially same kind of mass. And why then would this exchange become a “force”?

The description of the behavior of bodies must suffice us, I presume, because breakthroughs in the future will not provide any more knowledge than we have at present—only yet other hypotheses. Going down to have lunch now, I wonder if my mass will bend spacetime ever so, ever so faintly. Presumably so, if Einstein is correct.

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…