Answer 1:
The Big Bang created the universe 14 billion
years ago, so it would be impossible to see
anything farther than 14 billion light years
away, because nothing existed- not even space
or time. The most distant thing we can see is the
fading fireball of the Big Bang itself, a
bit less than 14 billion light years away. We
can't see the first instant of the Big Bang,
because the universe was too hot and dense- it
only became transparent when it cooled to a few
thousand degrees.
We see the fireball in any direction we look,
because the Big bang occurred everywhere- even
here. This is because space itself has
expanded. At the time of the Big Bang, space
was a single point, so everywhere in the universe
was all the same place (sounds like a garbled
sentence- but the wording is correct!) The
expansion of space has "red-shifted" the
fireball far down the electromagnetic spectrum-
down past red and infra red, all the way to
microwaves- so its now called the "cosmic
microwave background". >b>Red-shifting is
similar to the reduction of a sound's pitch as the
source speeds away from you. If not for this
phenomenon the fireball would still be bright,
like a sun covering the entire sky. Nothing in
space could be colder than the fireball, so the
temperature of space would be a few thousand
degrees. Thanks to the extreme red-shift, we
receive only a small fraction of the fireball's
original heat. It is possible for objects in
dark, empty space to cool down to about -415
degrees Fahrenheit, or 5 degrees above absolute
zero. This is the temperature of space!
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