endless universe?

Is the universe infinitely large. If the universe were finite in
size, what would be the barrier?

"T" == Tim923 writes:

T Is the universe infinitely large.

It would appear to be. The available evidence is consistent with a
certain form of the Big Bang model. One of the other predictions of
this model is that the Universe is spatially infinite. There is, of
course, no way to test this prediction, but it seems reasonable to
adopt it given the other successes of the model.

T If the universe were finite in size, what would be the barrier?

A finite volume (or area) need not have a barrier. Consider the
surface of the Earth.

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* Tim923:
Is the universe infinitely large.

It appears so.

Consider a finite universe of the particular kind where a "straight"
line out in any direction will eventually join itself in sort of
circle.

Then along that circle you see an object in non-accelerated free
motion coming towards you. Actually it's just a bulb on a very long
monofilament carbon string going the full circle, and it's moving,
relative to you. On the bulb is a digital clock and you read that
and then you calculate what someone else at rest wrt. you, say some
light-years down the line, would read right now (in your frame of
reference) on another bulb with its clock synchronized with the first in
the bulb/filament system. Well it won't be the same. You can make that
difference almost arbitrary large by picing a buddy farther and farther
away. But when you choose a large enough distance the buddy reading the
clock of the local bulb will be -- yourself, reading a different time.


If the universe were finite in size, what would be the barrier?

No barrier. As Joseph Lazio mentioned in his response, consider the
surface of the Earth, which is finite but unbounded in two dimensions.
The same idea goes for three or more dimensions, but then leads to a
non-intuitive topology. E.g., if you erected an infinite "flat" barrier
in space to split the universe in two, on each side of that barrier the
barrier would appear as the inside surface of a ball. It's the same as
those Flatlanders living on the outer 2D surface of a ball that try to
divide their 2D universe in half by erecting a straight line, and on
each side of that line they find that they're inside a great circle.

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On Sat, 19 Jun 2004 18:04:26 GMT, Tim923 wrote:

Is the universe infinitely large. If the universe were finite in
size, what would be the barrier?
As usual an edge, but none has been observed.

Finite galaxies, stars, and mass?

Billions of galaxies each having billions of stars is what I remember.

"Joseph Lazio" bravely wrote to "All" (19 Jun 04 14:22:23)
--- on the heady topic of " endless universe?"

JL From: Joseph Lazio
JL Subject: endless universe?
JL Organization: Posted via Supernews, http://www.supernews.com
JL Xref: aeinews sci.astro:33358

"T" == Tim923 writes:

T Is the universe infinitely large.

JL It would appear to be. The available evidence is consistent with a
JL certain form of the Big Bang model. One of the other predictions of
JL this model is that the Universe is spatially infinite. There is, of
JL course, no way to test this prediction, but it seems reasonable to
JL adopt it given the other successes of the model.

T If the universe were finite in size, what would be the barrier?

JL A finite volume (or area) need not have a barrier. Consider the
JL surface of the Earth.

I think the wrong question is getting answered. I suspect that size is
only a side effect of the passage of time. Clearly when we look at
distant objects we are really looking back in time. In fact everywhere
from where we are presently lies in the past. Matter and space could
just be like optical illusions caused by the passage of time between
events in which an energy transfer took place. As energy is dissipated
the past gets cooler until at some point the past will vanish from
view, an effect that is measured as the redshift. The energy liberated
in an event however is propelled forward in time into the future
direction where someone will be to observe its arrival. Time then is
just the temporal perception between events. The universe exists how
we perceive it now and observing it affects how we see it in the
future. Each century finds that the previous pardigm was flawed in
some way and a new idiom has to be reinvented. This is precisely
because we changed how we saw the universe. The universe is basically
inside our minds. Just watch out for big rocks falling from the sky,
that's the energy liberated from past events to nail us in the future!

A*s*i*m*o*v

.... Essay: Describe the universe in 500 words or less & name 2 examples.

"M" == Midjis *@*.* writes:

M Joseph Lazio wrote:
A finite volume (or area) need not have a barrier. Consider the
surface of the Earth.

M But the Earth's finite size is given limits by the fact that there
M is a place where the surface stops and the sky or space begins. If
M you measure from the core outward, sooner or later the Earth comes
M to an end on that line.

Re-read carefully what I wrote. I did not claim that the Earth had a
barrier. Indeed, the Earth is of finite volume and does have an
"edge." I specified the Earth's surface. If you think that the
Earth's surface has a barrier, where is it? In what direction and how
far do I have to walk before I reach the edge of the Earth's surface?

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On Sun, 20 Jun 2004 09:37:00 +0000 (UTC), Midjis *@*.* wrote:

Joseph Lazio wrote:

In what direction and how
far do I have to walk before I reach the edge of the Earth's surface?


Well, upwards. And hardly any distance at all. That is where Earth stops
and something else begins. And that seems to work pretty much however many
times I re-read what you wrote.

That is a very wishy-washy `edge' consisting of an ever `thinner'
atmosphere, ionosphere, etc. Can be a considerable distance in human
terms.

On Saturday, 19 Jun 2004 23:40:52 -500, "Asimov"
wrote:

The universe is basically
inside our minds.

The illusions and theories are there, along with one's personal
observations, but the real Universe is to universally observed in
space and time to be in our minds.

Each galaxy may not have billions of stars. How about the small ones?

Billions of galaxies each having billions of stars is what I remember.