Sunday, July 22, 2007

Listening to the Sky

I went to a public lecture by Geraint Lewis last night on cosmic background radiation and the inflationary model of the universe.

Curiously, I have come away with rather more scepticism about the Big Bang model than I had hitherto. I still think that the weight of the evidence is vastly in its favour. Declaring my biases, I still find it vastly more congenial to my worldview. However, I would no longer put it in the ‘that’s settled, then’ basket with continental drift and the evolution of all terrestrial life from a common ancestor.

(1) Briefly, the basic big bang model predicts background radiation in the universe that fits the blackbody radiation curve and is homogeneous with the same intensity in all directions. The steady-state model doesn’t. We have found background radiation which beautifully, definitely, fits the blackbody radiation curve. However, it is not homogeneous. Is it easier to tweak the big bang theory so that the radiation isn’t homogeneous, or the steady-state theory so that the background is thermal? Probably the former. And there are a lot of other problems with the steady state theory. Still, I can’t help wondering- if for purely historical reasons most theorists had stayed in the steady-state paradigm and devoted their lives to tweaking it, and only a few crackpots had kept beavering away at the big-bang model, would we have an elegant steady-state model today that fit all the data perfectly? Maybe we wouldn’t, but maybe we would. I just am not as sure as I was before that the universe is busily beating us over the head with the right answer.

(2) This is not an objection to the theory at all, but it is something I hadn’t known before, and it would certainly be something that would be shouted to the rooftops if a similar situation were to arise today- e.g., if a researcher affiliated with an oil company came up with a theory for climate change that confirmed the expected biases of their employer, even if it fit the data better than the anthropogenic global warming one. The Catholic church is not just perfectly happy with the Big Bang because it is consistent with Catholic ideas: it was a Catholic priest who came up with the theory.

1 comment:

Marco said...

I must say the point at which I became more skeptical was when stuff like "Dark energy" and "dark matter" and contradictory ages of the universe if calculated in different ways, started popping up. I think Big Bang theory has been chosen because it is conceptually easy to get your head around, not because the data fits neatly.