Tau Meson Posted January 9, 2010 Share Posted January 9, 2010 According to mainstream science, the entire universe is generally agreed to be "flat". Just how do we know that it is flat? How does the data from COBE allow cosmologists to conclude that it is flat and not, say, donut shaped? Link to comment Share on other sites More sharing options...
ajb Posted January 9, 2010 Share Posted January 9, 2010 I am not sure it is so easy to discover the global shape (topology) of the universe from the CMBR. However, the local geometry is apparent in the CMBR and this looks flat. This is done by carefully looking at the fluctuations in the CMBR. You derive a "power spectrum" from the fluctuations, that is a curve showing how the size of the fluctuations varied with angle. This agrees with the predictions for a flat universe to some reasonable degree of accuracy. Google COBE and Boomerang. Link to comment Share on other sites More sharing options...
Tau Meson Posted January 9, 2010 Author Share Posted January 9, 2010 I see. But, what I really want to know is what would the data look like if it was positively curved or negatively curved? And how small does the angle have to be, with respect to the power spectrum, to be able to decide if it is flat, round, etc. Link to comment Share on other sites More sharing options...
ajb Posted January 9, 2010 Share Posted January 9, 2010 I don't know. You would probably have to find a good graduate text on cosmology. Maybe someone else can recommend something? Link to comment Share on other sites More sharing options...
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