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2001-Dec-14, 12:53 PM
Hello all,

I really dont understand alot of stuff but was just wondering about one thing. Well anyway, lets assume the universe is like a big star. the big bang was when the universe first started burning fuel. However, because of the amount of energy produced it expanded quickly in such a matter that the galaxies expanded faster than light. The inital galaxies being the ones with the most energy, the closer ones being less. now lets say you are at the focal point of the beginning of the universe star. because of the speed at which the distances that the galaxies are moving away from you is approaching c or possibly exceeding it, time passes much more quickly for the galaxies first blown off, and much more slowly at the center of the universe. you cannot see back into the center because the distance has not been traveled by light yet, however the big bang is still occouring, until it runs out of fuel and the universe colapses like a big star, forming a black hole, possibly leading to the creation of another universe.

Just some thing i was thinking of, im sure it looks like swiss cheese without the cheese part. but what do you think

Silas
2001-Dec-14, 03:10 PM
The wonderful thing about cosmology is -- no matter how weird you think it is -- it really is even weirder!

Just for argument, let's say the current big bang theory is mostly right...

So, about 15 billion years ago, pop, it comes into existence, expands, and keeps expanding.

Like any ordinary cloud of gas, as it expands, it cools. What is at first a cloud of fiery hot gas cools down into a big cloud of cooler gases. These eventually clump up into stars and galaxies...

Now comes the weird part: there isn't any "center" of the cosmos. You can't travel to a place and say, "Aha, here is where the big bang happened." And that means (if correct) that the entire cosmos should look just about the same from any viewpoint... And that means that no part of the universe is really much older than any other part...

I dunno if I've answered anything, or just made it murkier... (Where is Isaac Asimov when we really need him?)

Silas

Chip
2001-Dec-14, 05:46 PM
Some of your ideas remind me of a Belgian mathematician and priest named Georges Lemaitre. He described the early universe as a "primordial atom" that then expanded (also without a center.) Albert Einstein described it as a 4 dimensional finite-yet-unbounded manifold.

Observation seems to indicate that there is no center to the universe. An observer at any point observes the universe expanding away from them. It's an incredible discovery. The Balloon Analogy (http://www.astro.ucla.edu/~wright/balloon0.html) is useful here.
A colleague of the Bad Astronomer named Ned Wright has an excellent page of frequently asked questions about the universe:

http://www.astro.ucla.edu/~wright/cosmology_faq.html

Chip


<font size=-1>[ This Message was edited by: Chip on 2001-12-14 14:16 ]</font>

CJSF
2001-Dec-14, 06:23 PM
An observer at any point observes the universe expanding away from them. It's an incredible discovery.


I am not trying to bring back the spectre of JW here, but there is NO DISCOVERY of an observer seeing the universe expand away from him/her at any point. NO PERSON OR INSTRUMENT has ventrued far enough away from Earth to demonstrate this first-hand. It may be true, but it hasn't been directly observed... yet.

CJSF

_________________
"Be very, very careful what you put into that head, because you will never,
ever get it out."
--Thomas Cardinal Wolsey (1471-1530)

<font size=-1>[ This Message was edited by: Christopher Ferro on 2001-12-14 13:24 ]</font>

2001-Dec-16, 09:21 PM
Why couldnt a univrse with a center not bee seen as expanding from every point. if space is actully welling up between points could not there still be a center point? And would relative time be the same between different galaxies/stars?

Russ
2001-Dec-17, 09:10 PM
The reason this business of the universe not having a center sounds so hokey is that the theory is based on math descriptions of physical characteristics. In our collective experience here on Earth if you have a ball or some other figure, intuition tells you there must be a center. In math, that isn't always true. Math constructs and extrapolations only have to have a non-erronious solution, so some pretty wierd things are possible.

Has anybody seen that there is no center to the physical universe? NO! Has anybody done a math proof that there is no center? YES. Does that mean that there really is no center? NO. All it means is that the math descriptions of our universe imply that there is no center. Until we have inter-galactic space flight capable of takings us 15 billion LY in a reasonable amount of time, any informed opinion is as good as another.

Is my answer here the final word? NO. If you can't deal with uncertainty, it's time to grow up and get over it. /phpBB/images/smiles/icon_smile.gif

lpetrich
2001-Dec-17, 10:34 PM
The whole question of the initial state of the Universe is an interesting one. It can be answered with the help of Stephen Hawking's singularity theorems, and the insight that the Big Bang is gravitational collapse run backwards.

If the Universe's contents follow some reasonable assumptions, then according to general relativity, the Universe had indeed begun as a point, a singularity. However, GR is a classical theory, and when the Universe had been compressed enough, quantum-gravitational effects are expected to appear. However, we have no good theory of quantum gravity, so we are stuck there.

It's thought that the Universe's expansion had gone through an exponential, Steady-State-like inflationary phase; if this phase had been permanent, then there would have been no initial singularity. This does not contradict Hawking's singularity theorems because one of their conditions is violated: in this phase, (pressure) = - (mass density)*c^2, while Hawking's theorems imply a singularity only if the = is replaced by a >.

Such a strong negative pressure is an expected consequence of a scalar, spin-0 field having a nonzero potential value and not changing in space or time. The inflationary phase would be a result of the field getting stuck in some metastable state -- and slowly moving toward some true stable state.

Since this is a very-early-Universe effect, this field must have a GUT-scale mass -- and some GUT's have possible candidates for this "inflaton" field.

2001-Dec-19, 07:04 AM
Okay another thing, lets say in another universe or previous universe, when it collapses it forms a singularity, with all the matter it was constitued of, then it bascically sprays that basic matter (all the subatomic particles) into another area, creating another universe. Perhaps matter is still pouring in from a collapsing universe. Possibly at some point our universe will have enough mass from the other universe to collapse itself.

think like coffe filters stacked over eachother, one soaks thorugh onto another, when it gets enogh water, wich soaks into another which soaks into another. so eventually our universe will pour out thorugh a massive singularity to create another universe, and since the singularity breaks down all particles the universe would basically be reset, into nothing but elementry atoms and such.

again, just a thought

Azpod
2001-Dec-19, 06:50 PM
On 2001-12-19 02:04, athsryan wrote:
Okay another thing, lets say in another universe or previous universe, when it collapses it forms a singularity, with all the matter it was constitued of, then it bascically sprays that basic matter (all the subatomic particles) into another area, creating another universe. Perhaps matter is still pouring in from a collapsing universe. Possibly at some point our universe will have enough mass from the other universe to collapse itself.

think like coffe filters stacked over eachother, one soaks thorugh onto another, when it gets enogh water, wich soaks into another which soaks into another. so eventually our universe will pour out thorugh a massive singularity to create another universe, and since the singularity breaks down all particles the universe would basically be reset, into nothing but elementry atoms and such.

again, just a thought


From what I understand, there is a theory that all BHs are in fact bubble universes, created by all the infalling material. However, if that were the case, someone in such a universe would not see a while hole with all the matter that is being sucked into the black hole pouring out of it. This is because of time dilation effects in areas of high gravitational fields.

In essence, an obvserver falling into a black hole would see the rest of the universe speed up as they approach the event horizon. Assuming they are going into a BH large enough where they don't get ripped to shreds by the tidal forces, they would see time pass so fast that as they passed the event horizon, it would appear to them as if the rest of the universe had aged into oblivion in a few microseconds. Because of this, all the rest of the infalling matter that the BH would ever collect would also appear to suddenly arrive at the event horizon at the same time that the observer did.

So if the infalling matter detonates into a Big Bang, forming another universe, it would do so outside of the time frame of our universe. It would have the mass of the BH, and nothing more. There would be no more matter from "our" universe falling in, nor would there be any way for anyone in this new universe to detect that our universe ever existed.

Chip
2001-Dec-21, 04:44 PM
On 2001-12-19 02:04, athsryan wrote:
Okay another thing, lets say in another universe or previous universe, when it collapses it forms a singularity, with all the matter it was constituted of, then it basically sprays that basic matter (all the subatomic particles) into another area, creating another universe. Perhaps matter is still pouring in from a collapsing universe. Possibly at some point our universe will have enough mass from the other universe to collapse itself.

think like coffee filters stacked over each other, one soaks through onto another, when it gets enough water, which soaks into another which soaks into another. so eventually our universe will pour out through a massive singularity to create another universe, and since the singularity breaks down all particles the universe would basically be reset, into nothing but elementary atoms and such.

again, just a thought


It might be helpful to consider that a "singularity" is a mathematical precept
that represents something else. It is a symbolic "understudy" for a real process
that is not fully understood.

A "singularity" need not be thought of as something tiny. Mathematically a "point" can be a location in time and not a current material entity. By analogy, imagine an infinitely dense compression of matter that goes on forever, then picture it expanding, becoming thinner over time.

Chip