Bad Astronomy: Misconceptions and Misuses Revealed, from ...

WHEN THE UNIVERSE THROWS YOU A CURVE 145
It didn’t take long for people to realize that this was characteristic
of an explosion. If you blow up a bomb, then take a snapshot of
the explosion a few seconds later, you see how shrapnel that’s farther
from the center must be moving faster. The fastest bits move the
most in a given time, while slower bits haven’t moved out as far.
This implies that the universe started in a gigantic explosion.
You can think of it this way: if all the galaxies are moving away
from us as time goes on, then they must have been closer in the
past. If you reverse time’s arrow and let it run backwards, there
must have been a time in the past when everything in the universe
was crushed into a single point. Let time run forward again, and
BANG! everything is set in motion.
And what a big bang it was, starting up the universe and sending
it flying. Could this be right? Did the universe start out as a
single point that exploded outwards? Perhaps no single scientific
theory has stirred people, incited their anger, their confusion and,
indeed, their awe more than the Big Bang theory. I suspect that
even Darwin’s observations on evolution may have to take back
seat to the biggest bang of them all.
But it does have one comforting aspect: it says we are at the
center, because everything is rushing away from us . . .
. . . or does it? Let’s use an analogy. Imagine you are sitting in
a movie theater, and the seats are packed together so closely that
they are touching. Furthermore, the seats are all on movable tracks.
I hit a button, and suddenly every seat moves so that there is now
one meter separating each chair. Your nearest neighbors are all one
meter away, in front of you, behind you, on your left, and on your
right. The next seats over are all two meters away, and the next
ones from those are three meters away, and so on. But wait! That’s
true for any seat in the house. If you got up and moved into a seat
a couple of rows up, and we repeated this experiment, you would
see exactly the same thing. The next seats over would be one meter
away, and the ones past that would be two meters away, and so
forth.
So no matter where you sit, it looks like all the seats are rushing
away from you. It doesn’t matter if you are actually in the center
seat or not!