If the Universe can rotate, why does it rotate so slowly? We formulate this 'rotation problem' by introducing a dimensionless measure of the angular velocity in the early Universe which must have been <5 × 10 -28 in order to be compatible with present-day upper limits on the rotation. Hitherto the slow rate of rotation has been explained only by invoking Mach's principle, which decrees that it vanish. Here we point out that an inflationary epoch in the very early Universe, proposed as a solution to other cosmological problems, could also solve the 'rotation problem', and thus make the Mach principle redundant.
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