Friday, December 06, 2013

State of the Universe

Back in the golden age of fundamental physics, maybe in the fifties, some young physicist was asked about a colloquium he had just attended.

"It was wonderful" he said, "Everything we knew yesterday is wrong!"

Physics isn't like that anymore. Paleo-anthropology yes, physics no.

Thirty years ago we had a comprehensive theory of matter, with a few sort of minor loose threads, and the universe looked big, but notable deficient in dragons or other big unknowns. Today our theory of matter looks just about the same, most of those loose threads having been since picked up. The big theoretical hope of those days, String Theory, is still around, but starting to look a bit long in the tooth. It's proving remarkably resistant to providing any new insights into how the world works.

The universe, on the other hand, is a bit more mysterious. It seems that that matter that we understand so well, only makes up about 5% of it. Dark matter - 25% or so - doesn't fit neatly into our Standard Model. Dark energy, the other 70%, is even more mysterious.

The most frustrating aspect of the mysterious 95% is that there are very few things that we can do to learn more about them. Roughly a century or so ago, physicists invented a wonderful hammer, the particle accelerator. Since then we keep whacking things with this wonderful hammer and marveling at what comes out. We have reached the point where new and improved hammers cost the GDP of a small country and there is little obvious hope that the next generation will discover anything really new. It looks like the best hope for new physics may lie with the astronomers, as they tease out a few more clues about dark energy.