Tuesday, May 19, 2009

Universe: Arguments against flatness (plus exposing sloppy science writing)

According to the always entertaining New Scientist, "Flat universe may be the new flat earth (Eugenie Samuel Reich, 18 May 2009). We are informed,
FOR centuries the ancients believed the Earth was flat. Evidence to the contrary was either ignored or effortlessly integrated into the dominant world view. Today we dismiss flat-Earthers as ignorant, yet we may be making an almost identical mistake – not about our planet, but about the entire universe.
Which centuries were those? The fact that Earth is a sphere was determined by Eratosthenes in the third century B.C.

"Flat" just means that light beams travel parallel to each other, instead of converging or diverging - these conditions would imply a negatively or positively curved universe. Most astronomers currently believe the universe to be flat, but ...

In a paper accepted for publication in Monthly Notices of the Royal Astronomical Society (http://arxiv.org/abs/0901.3354), they took data from WMAP and other cosmology experiments and analysed it using Bayes's theorem, which can be used to show how the certainty attached to a particular conclusion is affected by different starting assumptions.

Using modern astronomers' assumptions, which presuppose a flat universe, they
calculated the probability that the universe was in one of three states: flat, positively curved or negatively curved. This produced a 98 per cent probability that the universe is indeed flat. When they reran the calculation starting from a more open-minded position, however, the probability changed to 67 per cent, making a flat universe far less of a certainty than astronomers generally conclude.

Doubtless. But don't expect them to try that kind of rigour any time soon on origin of life theories or the ability of Darwinian evolution to produce vast amounts of new information.

(Note: Of course, it was always possible to think that Earth was a donut. But the examples of the sun and the moon would deter most reasonable people. Come to think of it, a donut-shaped Earth would be an interestng piece of artwork. Anyway, I think it is time to give up on myths about what our ancestors believed or else cite sources.)