Tuesday, October 13, 2009

Top Ten Basics Still Not Completely Understood: Number Seven*

Gravity. We get it, but we don't really get it. I think it's a wonderful testament to the complexity of the physical universe that even today our picture of something so intimately involved in our daily lives is incomplete. We've eked out its rules and can predict how it will behave, true. We have theories that hold up well to experimental evidence. Einstein united space and time in a single concept, Spacetime, and theorized that gravity was caused by mass bodies creating "wells", or four-dimensional troughs in Spacetime into which other massive bodies are drawn.

But our theories don't work perfectly. A basic particle involved in gravitation has been predicted, the Graviton, but it's never been found experimentally. It exists solely, as of yet, in mathematical models. And another mind-bender is the prediction that two massive bodies will attract each other no matter the distance between them, assuming there are no other bodies closer to counteract the pull. So two planets 100,000,000,000 light years apart will be drawn into each other's gravity, assuming they are the closest massive bodies to each other, regardless of their size.

There is still a part of the puzzle we're missing. Theorists have attempted to unite gravity and quantum theory, so far with only limited success. It's remarkable to me that, even on its most basic levels the universe manages to keep its cards hidden. It gives us a taste, but it never shows its whole hand. But one day, I suspect in the next 100 years we'll work it all out. We'll find a "theory of everything" that unites all scientific disciplines in a total picture of the universe. One that's testable, verifiable, and wholly consistent.

Because the current incompleteness of our understanding of gravity is also a testament to the tenacity of science. If we were to call our limited and flawed understanding "complete" we would be doing ourselves a disservice. But we aren't willing to settle for partial explanations, or theories that are "close enough". We, meaning humanity, strive for perfect clarity, elegance of solution and an understanding where all explanations in a given system agree with on another.

I have faith that we'll get there.

*As determined by choosing the first number that came into my head.

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