Re: A stellar explosion has smashed the record for most distant object in the known universe.

Rumpelstiltskin wrote:
On Wed, 29 Apr 2009 18:47:39 -0700, Islander <nospam@xxxxxxxxxxx>
wrote:

rick++ wrote:
On Apr 29, 9:32 am, mg <mgkel...@xxxxxxxxx> wrote:

Our smallness really does boggle the mind, doesn't it. The only
half-way appropriate comment I can think to make, other than that, is
contained in this little prayer:
Other people are disturbed the known universe is finite:
only 13.7 billion years old and 27 billion light years wide.
They ask what is "before" the beginning or "beyond" the edge.
Stephan Hawking saws this is like asking what is "north"
of Earth's North Pole.
OK, now this is something that I don't understand. As we look further and further out into the known universe we are looking back in time as well. So, if we look far enough, we will see, not the edge of the universe, but the origin of the universe. That origin, as evidenced by radio signals associated with the Big Bang, is everywhere equidistant from us as nearly as we can tell. We are at the center of the universe. Likewise, the theory claims, every other body in the universe is equidistant from the Big Bang. Yet, there are vast distances separating us! How can that be?


I don't know the answer, but I'll take a shot that the big bang was not a symmetrical event. The fact that the galaxies are in clumps might suggest that, but that could
also be attributed to quantum randomness. Quantum
random events were probably galaxy-cluster sized in
the first picoseconds of the big bang.

I'm not sure that the fact that the big bang radiation
is uniform over the sky means that we're at the center. If we're not at the center, the stuff from farther away has
a greater distance to go, but there's more of it in that direction. This exactly cancels out, analogous to what
Newton proved, there is no resultant gravity anywhere inside a uniform shell: the nearer material pulls harder,
but there's mores material at the far end in the same angular slice. It exactly compensates. Thus if you were inside a circular cell and had only gravity to go by, you couldn't tell how near you were to any part of the shell.

Now, that makes a great deal more sense than Hubble's raisin cake explanation. Thanks!

Earth is a series of concentric shells, so the gravity
at the center is zero, though the pressure is enormous.

A related thing that Newton showed is that if you're
outside (as opposed to inside) a uniform shell, the gravity is the same as if all the mass of the shell were concentrated at one point in the center of the shell. Thus to determine the gravitational pull at some point inside the earth, you just have to compute the mass
of everything closer to the center than you are, and the distance you are from the center. The net pull of everything closer to the surface than you are is shells that you're "inside", so the net pull of those
is zero.

The cosmic background radiation comes from one concentric shell, so no matter how close to or far from any side we are, the effect will be the same
in all directions. This is all just my guess, there might be something wrong with it.

Also, the universe is supposed to curve back
on itself in four dimensions, and if so then saying that we're at the center of the universe is like saying that San Francisco of Sydney is the center of the surface of the earth. There is of course no
center of the surface of the earth. Wherever you are on it, that looks like the center. A city on the
surface of the earth sits on a two-dimensional figure that curves in three-dimensional space, and our solar system sits on a three-dimensional figure that curves in four-dimensional space, thus they're analogous.


The only course that I failed in college was n-dimensional tensor theory. Once I get beyond 3 dimensions, I have difficulty visualizing it, probably because I am stuck in 3 dimensions. I guess that means that I will never understand string theory.
.

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