This is us.
Beyond our aeon here.
The previous aeon down here.
What we have here are the encounters between
black holes, huge ones, at galactic centers.
Every now and again, in a cluster of galaxies,
black holes will encounter each other; sometimes
they will escape, with gravitational waves
coming out; that is the gravitational version
of light; or they may swallow each other up,
these are the most dramatic situations.
When they do that, there will be a great burst
of gravitational radiation coming up and this
will make a mark on this initial surface.
The picture I suggest you have is a pond when
it’s pretty calm and it rains and rain causes
a ripple.
After a while the rain stops.
The events of the rain falling, those are
the black hole encounters.
After the rain stopped, that is when all the
black holes disappeared, and you look at the
pond it looks like a … mess.
But if you do some … statistics on it, you’ll
be able to work out that this mess is caused
by individual impacts.
So about a year and a half ago, when I was
in Princeton, I asked David Spergel, who is
the expert on … cosmic microwave background,
‘has anybody ever seen evidence for disturbunces
in the cosmic microwave background’ and
he said to me ‘No, they haven’t. But then
nobody’s ever looked.’ (laughter)
Then he said ‘It wouldn’t be too hard
to do. Just give me a couple of weeks and
I let you know.’. That was about a year
and a half ago (laughter) so after months,
he gets me his student to give me his results.
The student did a very nice analysis and the
answer came out … a bit very strange. Because
it looked to me as if there was something
 … but to see whethere that was right or
not, I suggested ‘why don’t you give the
sky a twist, in your imagination, and then
what’s a circle will cease to be a circle
and if those … that pat signal is still
there, than it’s spurious. If the signal
goes away there is a real indication’.
What did I see? He said ‘I can do a small
twist and then a big twist.’. Short story
is, In a certain big range of angles of circle
diameter, we found that a small amount of
twist actually increased the signal and a
big twist made it disappear. So I said ‘are
you sure you haven’t got your colour coding
wrong? It should surely be the other way around.’
 … and he was right. He was right.
So what this suggests is that, in this environment,
what you see as a circle has actually been
distorted into something a little elliptical,
because the radial mass distributions aren’t
there.
And that’s what I think is likely to be
going on in side the CMB. And what we need,
is some way of entangling the distortions
due to irregular mass distributions to see
if this effect is really there or not.
There are possibilities of doing that, but
at the moment that’s not being done. Tantalizing
 … how long I have to wait before somebody
will do that. (Mutter) you need to take into
account the distortions due to the irregular
mass distributions, this is the thing, they
are not … this is a pretty scarce signal
from earth. We should … on it.
