Beyond the Room

By Sean Carroll | July 14, 2008 10:21 am

I’m sure Ruben Bolling is making fun of people I disagree with, and not of me.

The underlying point is a good one, though, and one that is surprisingly hard for people thinking about cosmology to take to heart: without actually looking at it, there is no sensible a priori reasoning that can lead us to reliable knowledge about parts of the universe we haven’t observed. Einstein and Wheeler believed that the universe was closed and would someday recollapse, because a universe that was finite in time felt right to them. The universe doesn’t care what feels right, or what “we just can’t imagine”; so all possibilities should remain on the table.

On the other hand, that doesn’t mean we can’t draw reasonable a posteriori conclusions about the unobservable universe, if the stars align just right. That is, if we had a comprehensive theory of physics and cosmology that successfully passed a barrage of empirical tests here in the universe we do observe, and made unambiguous predictions for the universe that we don’t, it would not be crazy to take those predictions seriously.

We don’t have that theory yet, but we’re working on it. (Where “we” means an extremely tiny fraction of working scientists, who receive an extremely disproportionate amount of attention.)

CATEGORIZED UNDER: Humor, Philosophy, Science

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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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