eh

Hey Tim, quick question.

Andrei Linde has been very critical of the cyclic brane collisions. In his latest attack, he said the only ones taking the theory seriously are the press. In other words, he says cosmologists aren't impressed. Do you know if this is the case?

Tim Thompson

I think maybe Linde exaggerates; he is, after all, a leading opponent of the "cyclic" idea. The original paper, published in December 2001 (but available as a preprint since March 2001), has already garnered 22 citations, including theoretical support from other authors.

Linde coauthored two critical papers in the same Dec 2001 issue of Physical Review, and has continued to criticize the "cyclic" hypothesis.

Inflation offers an explanation for the formation of the first structure (a solution to the "homogeneity problem"). The cyclic universe hypothesis likewise offers a solution, in the expanding space between colliding branes. Linde thinks it won't work unless they include an inflationary period.

I would call them both viable ideas, though inflationary theory has been around longer, and is better known. Scientists champion their own ideas, and I am in no position at the moment to call one side smarter than the other. But the paper trail makees it look like Steinhardt & Turok are enhancing & improving their hypothesis with time. We'll just have to wait a few years and see what pans out.

Answerer

Guys, how about hyperspace? I had heard people talking about it and that our universe is actually just a vaccum fluctuation of the hyperspace.