Big Bang or Big Splat?

Joseph Lazio wrote:
"BC" == Bob Cain writes:


BC Joseph Lazio wrote:


This statement fails to distinguish between the observable
Universe, which did indeed once fit inside a space smaller than the
head of a pin, and the entire Universe, which may very well be
infinite in extent.


BC How long would it take such a universe to become infinite?

The Universe didn't "become" infinite in spatial extent (if in fact it
is).

Right, nothing can "become" infinite. It was a leading
question. We are left, it seems, with the idea that if the
universe is infinite in extent, it went spatially from
nothing to infinite in the initial instant. That's really
hard to come to any kind of grips with.


The problem here is that many people (based in part on poor
descriptions from my learned colleagues) think that the initial
singularity in the Big Bang model was a point in space. It wasn't.
It was a point in time.

But what can be said about space at that time. If there was
no time before that point, was there no space either?


Thanks,

Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Bob Cain" wrote in message
...

Right, nothing can "become" infinite. It was a leading question. We are
left, it seems, with the idea that if the universe is infinite in extent,
it went spatially from nothing to infinite in the initial instant. That's
really hard to come to any kind of grips with.


No, the theory is the universe has always been infinite.

"Bob Cain" wrote in message
...

The problem here is that many people (based in part on poor
descriptions from my learned colleagues) think that the initial
singularity in the Big Bang model was a point in space. It wasn't.
It was a point in time.

But what can be said about space at that time. If there was no time
before that point, was there no space either?

Correct. It went directly from "no space or time"
to "time is ticking and space is infinite" by some
process which is not yet understood. It did pass
GO but did not collect UKP 200.

George

"BC" == Bob Cain writes:

BC Joseph Lazio wrote:

This statement fails to distinguish between the observable
Universe, which did indeed once fit inside a space smaller than
the head of a pin, and the entire Universe, which may very well
be infinite in extent.

BC How long would it take such a universe to become infinite?

The Universe didn't "become" infinite in spatial extent (if in fact
it is).

BC Right, nothing can "become" infinite. It was a leading question.
BC We are left, it seems, with the idea that if the universe is
BC infinite in extent, it went spatially from nothing to infinite in
BC the initial instant.

Not really. As we currently understand physics, we cannot describe
the "initial instant." Rather we extrapolate backward in time. For
extrapolations beyond a certain point in time, our extrapolations
become increasingly less certain.

A simple naive extrapolation would indicate that at a finite time in
the past, the temperature and the density of the Universe became
infinitely large everywhere. That's the initial singularity or the
"instant" of the Big Bang. That's also what I mean by, if the
Universe is infinite, then it's always been infinite.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

Joseph Lazio wrote:

In contrast, the spatial extent of the Universe could be infinite. If
so, it always has been infinite.

Another question, if I may. If the extent is infinite does
that imply that there are guaranteed to be other regions (an
inifinite number possibly) the size of our visible universe
that have the identical quantum state? I seem to remember a
Scientific American article that asserted this.

Further, does such a universe guarantee regions the size of
our visible universe which exhaust the possible quantum
states of such a region. You know where I'm going, I'm
sure. If this is true then the ultimate anthropic principle
seems to be that we are here seeing what we see simply
because it is possible. The only mystery that would be left
relative to our existence is the infinitude itself that
provides for it.

Further yet, can symmetries be broken differently in
different regions and if so does that say that all possible
tunings, including the fine one we find ourselves in, must
exist somewhere, somewhen?


Thanks,

Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"BC" == Bob Cain writes:

BC Joseph Lazio wrote:

In contrast, the spatial extent of the Universe could be infinite.
If so, it always has been infinite.

BC Another question, if I may. If the extent is infinite does that
BC imply that there are guaranteed to be other regions (...) the size
BC of our visible universe that have the identical quantum state? I
BC seem to remember a Scientific American article that asserted this.

This is starting to veer more into the philosophical rather than
scientific, but I think so.

If the Universe really is spatially infinite, then I think one is
forced to the conclusion that there are infinite numbers of me typing
out this response right now.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

"Bob Cain" wrote in message
...


How long would it take such a universe to become infinite?


It has always been infinite. We have no frame of reference to describe time
after or before the universe or size after or before the universe.

In article ,
Joseph Lazio wrote:

"p" == p6 writes:

A universe with billions and billions and billions of galaxies that
once fit inside a space smaller than the head of a pin is just
well, hmm.. a bit far out

This statement fails to distinguish between the observable Universe,
which did indeed once fit inside a space smaller than the head of a
pin, and the entire Universe, which may very well be infinite in extent.

OTOH even the observable Universe has more than a few billion
galaxies, doesn't it?

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/

p6:
What's more likely. A Big Bang where everything starts from
a singularity or M-theory Big Splat (ekpyrotic scenerio)
where two higher dimensional colliding branes produced
the matter and energy in our universe??
...
I think Big Splat (ekpyrotic scenerio) is more likely
than a Big Bang (which is a bit way off). What do you
think?

Chris L Peterson:
I think it is unscientific to make what are, essentially, guesses as to
likelihood. Do you have any reason other then personal philosophy for
favoring one explanation over the other? On a personal scale, either is
mind boggling.

Yes, of course. But I have heard eminent cosmologists speak on this
subjects, and their talks are full of "we can only guess," "our best
guess is," "your guess is as good as mine," "it is my guess," and the
like. I would guess that making guesses based on incomplete data is
human nature.

It has been proposed that there are actual observations possible that
can invalidate the colliding branes theory. For myself, I'll withhold
judgment until such observations are made.

Me. too. I am as keen as anyone to know the answers to the Big
Questions. It is unlikely that I will discover those answers for
myself, however, so I wait patiently for researchers to make new
discoveries, which I will digest as best I can. Meanwhile, I will
continue to fantasize about possible answers to the Big Questions, just
as the OP did, and I will be grateful that this is sci.astro.amateur
rather than sci.astro.rigorously.correct, a newsgroup that might not
welcome the OP, and that would certainly not me. Perhaps there ought to
be a sci.astro.limping.along.and.doing.what.we.can for people like me
who fail to meet the rigorous standards that some would impose on this
group.

Davoud

--
usenet *at* davidillig dawt com

On Mon, 11 Jul 2005 10:02:20 -0400, Davoud wrote:

Yes, of course. But I have heard eminent cosmologists speak on this
subjects, and their talks are full of "we can only guess," "our best
guess is," "your guess is as good as mine," "it is my guess," and the
like. I would guess that making guesses based on incomplete data is
human nature.

Certainly, and there is much in cosmology of a speculative nature. I
have no argument with discussing such theories here (and the colliding
brane one is quite interesting). My objection was only that no purpose
is served in soliciting people's philosophical viewpoint on these
different theories. One of your eminent cosmologists may (and should)
point out where in a theory the guesswork lies; I would hope he wouldn't
ask for an audience vote, however!

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com