Measuring the expansion of the universe

Abstract

We draw a figure from where it is possible to measure the number of e-folds of expansion of the universe with a ruler. We find model independent bounds for the number of e-folds during inflation, reheating and radiation. We also give a lower bound to the size of the universe at the beginning of observable inflation. Finally, we show that consistency with a relevant diagram requires the existence of a new form of energy to drive the present expansion of the universe.

arXiv comment13 pages, 4 figures, 1 table. A new section has been added. Improved presentation. Misprints in Table I have been corrected. Version sent for publication

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