On 17/04/2013 5:10 PM, Steve Willner wrote:
There are other sources of gravitational radiation in the early
Universe, but those all lead to E-mode polarization. It's
specifically the B-mode polarization that is the signature of
inflation.

What do the E- and B-mode polarizations mean anyway? B-mode I'm guessing
is the type that is caused by Inflation only, and it's expected to have
a wavelength as large as the observable universe. How do you detect a
wave that big that you may be sitting right on top of?

There's an overview at
http://www.b-pol.org/bpol-science.php
and more illustration at
http://cosmology.berkeley.edu/~yuki/CMBpol/CMBpol.htm
(Read "gravitational waves" where these sites write "gravity waves.)

Good stuff, I'm reading through the first one, I'll get to the second a
bit later.

The short answer (as far as I can tell, not being an expert on this
subject) is that the origin of the polarization is quantum
fluctuations, which are initially tiny but magnified by inflation.
Without inflation, there's no such magnification or at least not
enough to make the signature observable.

If anyone has a clearer (or more accurate!) explanation, I'd love to
see it.

So far this thread has been occupied mostly by kooks, hopefully somebody
in the field can see this and answer?

Yousuf Khan