The Big Bang?
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I used to wonder if there was a big bang then...

Wouldn't the light from the bang have long past us? But we see very old
galaxies. I have pictures of them on my computer desktop background.

Wouldn't we see these galaxies just in one direction? But they appear
more or less equally in all directions, right down to the CMBR.

The answer is, my thinking was wrong. It wasn't a "bang" - stuff
stayed still and space itself expanded, dragging stuff with it.
Should have been called the big whoosh instead, bang implies stuff
being propelled outward. But that just doesn't fit what we can see.

Assume for a second (ignoring inflation etc) that the "edge of space"
constantly radiates outward at the speed of light. Not saying it does,
just a tool to visualize. At 300,000 years after the big whoosh the size
of the universe would be 600,000 light years across and two points within
this bubble separated by 300,000 light years would be moving away from
each other at the speed of light... thus the light from point A would take
infinitely long to reach point B. Remember it's space expanding. Think of
light as an ant on a sheet of rubber being stretched at the edges as fast
as the ant can walk... at a certain distance the ant can walk forever and
never make it, even though initially the points were quite close.
We're within the bubble being stretched, not on the edge, so to us
galaxies we see with redshifts corresponding to 12 billion light years
away (assuming the age of the universe is about 14 billion years)
were initially 2 billion * 12/14 or 1.71 billion light years away
from our spot in the bubble when that light started its journey.
Disclaimer - my math might be off but conceptually that doesn't matter.
For an object with a redshift corresponding to 1 billion light years
away, the original distance when the light left the object would be
roughly (14-1) * 1/14 or .93 billion light years. Very roughly. This
assumes the universe is 14 billion years old, and the edge of space
is constantly receeding at light speed. These assumptions most likely
are *not* true (latest evidence is the rate of expansion is actually
increasing, and this simple analysis totally ignores the period of
inflation that occured before things like "speed of light" came into
existence - but nevertheless regardless of the specifics the concept
is space expands and drags along otherwise motionless stuff).

Thus... we see the CMBR and galaxies coming from all directions,
and even though the universe started out small, it still took light
from the initial events a very long lime to get to us.

There are some implications of this theory... one is that in the
existence of our solar system space has expanded by about a third.
But that doesn't mean everything gets bigger, it's only a very very
slight outward pressure that would cause objects not gravitationally
bound to one another to separate by that amount. The force of gravity
is so strong over close distances the separation of space over time
is not significantly noticed by gravitationally bound systems.

Another implication is the size of the universe (at least our universe)
is huge but still finite, so we don't have to worry about things like
"Boltzmanm's Brain" which theorizes in an infinite universe random
fluctuations result in self-aware entities just like us with everything
around us just a "fake" fluctuation. Of course that just can't be :-)
And silly stuff like that doesn't happen in a non-infinite universe.
At least not until it expands infinitely then perhaps a fluctuation
could result in anything, including an entirely new universe. Given an
infinite amount of time to wait for it to happen. We can observe a beginning,
which implies this particular universe has a very long way to go before
random fluctuations has any significant chance of fluctuating an exact
copy of pretty much anything complex. Recent spectacular science shows
on TV (the multiple universe one) are misleading, at least about copies
of us in *this* universe. It ain't big enough. Who knows what might be
going on in other universes, if they exist (the fact that this one exists
seems to imply that other separated universes might possibly exist).

Terry Newton 8/16/2009

Note... the above explanation is VERY approximate, I am not an expert
in these matters. Rather, it was a few thoughts I had after watching a
speech by Sean Carrol and Mark Trodden on bloggingheads.tv, the video
was at: http://brainwaveweb.com/diavlogs/21709

Further thoughts 9/2/09...

The real mind-blower is trying to imagine the pre-inflation universe
when the mass of billions of galaxies was crammed into a space smaller
than a proton. According to prevailing theory immediately after the
bang inflation almost instantly expanded this into a more roomy space
of about 10cm. But all is relative... to a subatomic partical in a
super-dense universe operating on pico-second timing, 10cm is huge.
If the bang actually happened everywhere at once, that "little" clump
of particles wouldn't know it and neither would we, for it defined
the limits of our observable universe today.

Also, there is a lot of "pressure" to (try to) explain what "caused"
the big bang, and what came "before" it. Tough subject since it's
often theorized that time itself was created in that early instant.
One idea is the "Brane" theories (aka M-theory for membrane), where
two spatial membranes touched and set off the whole thing. Another
idea is the inflation is infinite but areas within it "cooled" to
form many post-inflation bubbles, our universe being one of them.
What we can see and measure and confirm seems to support some variation
of an inflationary scenario, things before and beyond that are subject
to much speculation (but even then at least the math needs to work).

Links... (valid as of 9/2/09, subject to change)

http://www.atlasoftheuniverse.com/universe.html - maps of the universe
http://www.atlasoftheuniverse.com/redshift.html - animation of the light race
http://www.atlasoftheuniverse.com/bigbang.html - everywhere at once? maybe...
http://blogs.discovermagazine.com/cosmicvariance/ - various topics
http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/cosmo.html
http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/inflation.html
(from http://www.science.smith.edu/departments/Physics/fstaff/gfelder/index.html)
http://arxiv.org/ - HUGE library of (very) technical research papers