Re: The other direction
- From: "N:dlzc D:aol T:com \(dlzc\)" <N: dlzc1 D:cox T:net@xxxxxxxxxx>
- Date: Thu, 23 Mar 2006 20:16:46 -0700
Dear ajiko:
"ajiko" <ajiko2004@xxxxxxxxx> wrote in message
news:44225586$0$95986$742ec2ed@xxxxxxxxxxxxxxxxx
A recent lecture described the accounting of the matter in
the universe. It went something like this:
1) Ordinary mostly luminous matter in galaxies <X>
2) Dark matter surrounding galaxies <Y> (based on
velocity distribution of the stars).
Actually quite a quantity within the disk of spiral galaxies as
well. Notice also that they are now finding quite a number of
"quiescent" black holes at places other than the center of
galaxies. These will also act like centers of Dark Matter...
3) CBR indicating an overall flatness to the universe
that then implies a total amount of matter (using GR).
4) Leftover matter, about 80% must be somewhere.
Exotic matter theories sprout up.
It is considered that we are now capable of seeing all
the galaxies in the universe using the HST.
Not really. The most recent measurements indicate that inflation
blew the Universe up beyond our visible horizon, based on
reporter's understandings of what was said. Further expansion
will have pushed even more over our horizon.
This is used to determine the matter in (1) above. I don't
understand this. The sky is basically uniformly
covered with galaxies in all directions. To me this has
implications.
Pick the farthest galaxy we can see, say about 13
billion light years away.
Quasars, yes. Galaxies, I think only about 11 Gly away.
We see it forming as a quasar 13 billion years ago.
Imagine an astronomer in that galaxy 13 billion years
later looking out toward us. He will see our galaxy as
it is forming 13 billion years ago. What will he see if
he looks in the other direction? Can WE see any of
the galaxies he sees in that direction?
Possible, yes.
To me, it seems like the relative directions of motion
of all the galaxies are already basically determined
at the time the galaxies start to form.
Makes sense.
To me, it seems the energy-matter content of the
universe must continue on quite a long way beyond
that farthest visible galaxy.
This doesn't follow. It is entirely consistent with theory and
observation that spacetime is a product of the mass-energy in the
Universe, and that the total quantity of mass/energy is large but
finite. Does the value for c derive from the Universe at large?
We don't see the galaxies out there because they are not yet
lit up -
not quite separated out into galaxies.
We have very little observation history to go on. There are some
places where new galaxies appear to be springing into existence,
but there is a large quantity of matter there that is as you say
"unlit".
This cannot have been overlooked. So perhaps someone
can describe how GR can make the sky also look
uniformly distributed from the point of view of that
astronomer far, far away while not having an enormous
amount of additional energy or matter.
http://www.astro.ucla.edu/~wright/cosmo_01.htm
And since you asked:
"The laws of physics are the same for all inertial observers."
This couldn't be true in a Universe that didn't see about the
same things we see now, no matter where you did your observing
from.
David A. Smith
.
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