Asri-unix.927
net.space
utcsrgv!utzoo!decvax!ucbvax!C70:sri-unix!DIETZ@USC-ECL
Tue Mar 9 07:39:09 1982
Background Radiation
The reason we see an anisotropy in the background radiation is (they think)
because our galaxy is being drawn towards the center of a supercluster
of galaxies, roughly in the direction of the virgo cluster.
The background radiation does not provide a prefered reference frame,
because it doesn't provide ANY well defined reference frame. It expands
along with the rest of the universe, so the rest velocity defined by
the radiation several billion light years away is going to be a good
fraction of c different from what it is here.
On another topic, I read an interesting article in a recent Science
about a new theory on the origin of the universe. This theory postulates
that our universe is embedded in a larger space that is called a
de Sitter space. Thiis space has the property that separate points
move apart exponentially as time progresses. So, de Sitter space is
chock full of event horizons which produce lots of Hawking radiation.
This Hawking radiation causes the space to expand, generating more event
horizons, etc. The space has a density of around 10^93 grams per cc and
a temperature of 10^31 degrees K. Ocasionally, a phase transition
in this space causes a bubble to appear. This bubble expands at the
speed of light. Hawking radiation seeps in from de Sitter space making
a big bang.
This theory is nice: it avoids singularities at time 0, it provides for
the existence of many universes (justifying the anthropic principle),
it explains why the background radiation is so homogeneous (because
de Sitter space is). It doesn't explain where de Sitter space comes from,
though.
A final note: I read somewhere about a nifty effect of relativity.
Consider the view from an *accelerating* starship moving near c. For
any acceleration there is a speed at which strange things happen:
light emitted by a stationary observer behind the starship follows the
starship forever but never quite catches it. In effect, the starship
has created a black hole behind itself. This event horizon behaves
just like a black hole and emits Hawking radiation. For reasonable
accelerations this radiation will be very cold, however.
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