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# Do Black Holes Equal Universes?

sarek

1
Tue 18 Nov, 2008 02:03 am
@validity,
validity wrote:
I think it does. In the analogy of the cannonball, the cannon would be at the centre of the universe. If there was such a centre, where all matter exploded outwards from, then there is pre-existing space in order for the matter to move into. Not only is there a centre, there would be a leading edge or boundary of matter, beyond which is empty space. The most powerful telescopes do not see empty space at the limit of observation, they observe the cosmic microwave background radiation. There is no empty space waiting for matter to whiz through.

Yes, I admit I struggled with that problem as well. You effectively need to translate a 3D analogy into a 3-plus-whatever D reality. And it is not certain what the effect would be. That's the hurting head part.

Still, questions remain:
Would our universe in the absence of any mass at all revert to a 3D universe?
Is the universe infinite in an absolute sense, or does it only appear so to observers because it is curved and we simply can't see past 14 billion light years?
Or is it strictly finite and will it only become infinite after an equally infinite amount of time has passed?

validity wrote:
While it is true that you can think of each point in the universe in a relativistic sense as being the centre of the universe, I do not think the analogy of all matter (cannonball) exploded out from a source (cannon) is compatible with this. If the Milky Way can be considered the centre of the universe, then where is the cannon that the Milky Way came from? If it is equally valid that Andromeda is the centre of the universe, where is its cannon etc.

An infinite number of Planck sized cannon perhaps?

validity wrote:

...
It is the distance between sufficiently distant galaxies that is expanding. In the analogy of the cannonball, there is no explosion in the cannon that propels the cannonball. The distance between the cannon and the cannonball grows over time. There is no energy imparted from the cannon to the cannonball. The cannonball becomes more distant from the cannon due to an unseen force.

Am I correct in assuming that the concept of seeing the expansion of the universe as a geometrical effect rather than as a force is comparable to what Einstein did to Newtons concept of gravity? To mere mortals falling out of tall buildings gravity still feels like a force(or rather the shedding of accumulated KE upon landing does)

validity wrote:
It is becuase that it is correct to think there is no true centre, that removes the idea that there is an outward explosion of matter in pre-existing space.

This is why I was unsure if KE and PE could be used.

I still need to think about this. If we launch a rocket we can surely use KE and PE, no question. If we consider the orbits of planet around stars and even of stars in galaxies we can still use them. The concepts are even used in the virial theorem. Why would they not work on the macroscopic level?
BaCaRdi

1
Tue 18 Nov, 2008 10:07 am
@sarek,
sarek wrote:
Yes, I admit I struggled with that problem as well. You effectively need to translate a 3D analogy into a 3-plus-whatever D reality. And it is not certain what the effect would be. That's the hurting head part.

Still, questions remain:
Would our universe in the absence of any mass at all revert to a 3D universe?
Is the universe infinite in an absolute sense, or does it only appear so to observers because it is curved and we simply can't see past 14 billion light years?
Or is it strictly finite and will it only become infinite after an equally infinite amount of time has passed?

An infinite number of Planck sized cannon perhaps?

Am I correct in assuming that the concept of seeing the expansion of the universe as a geometrical effect rather than as a force is comparable to what Einstein did to Newtons concept of gravity? To mere mortals falling out of tall buildings gravity still feels like a force(or rather the shedding of accumulated KE upon landing does)

I still need to think about this. If we launch a rocket we can surely use KE and PE, no question. If we consider the orbits of planet around stars and even of stars in galaxies we can still use them. The concepts are even used in the virial theorem. Why would they not work on the macroscopic level?

Agreed here!
Would our universe in the absence of any mass at all revert to a 3D universe? <--nope it's many more than that..agreed.

The Universe is indeed timeless....agreed!

The concepts are even used in the virial theorem. Why would they not work on the macroscopic level? <--- agreed! Nano to Macro are nondiscriminations of the forces at hand....

Thank you my friend;)

-Marco
xris

1
Tue 18 Nov, 2008 12:58 pm
@BaCaRdi,
I mentioned the torus some time ago and step by step you appear to be approaching the same conclusions but a bit toooo slow for me ..can you google it please ..
0 Replies

sarek

1
Tue 18 Nov, 2008 03:40 pm
@dkane75,
This torus topology seems like an interesting idea. If I understand this right it would be consistent with a critical density universe(not an open or closed one).
There is just enough elegance to the theory to be true, I admit. The way they derived it through measuring frequency variations in the cosmic background radiation is indeed a great example of scientific thinking.

It does feel a little claustrophobic though:). We only get to run in short circles.

Next question: why would it be shaped like this?
xris

1
Tue 18 Nov, 2008 04:00 pm
@sarek,
Depends on what you call short...
validity

1
Wed 19 Nov, 2008 12:00 am
@sarek,
sarek wrote:
I still need to think about this. If we launch a rocket we can surely use KE and PE, no question. If we consider the orbits of planet around stars and even of stars in galaxies we can still use them. The concepts are even used in the virial theorem. Why would they not work on the macroscopic level?

I am not saying that they would not work, I am questioning the use of the term KE for two sufficiently distant galaxies that the region of space between them is expanding, as the galaxies have not had energy given to them by an explosion that propelled them outwards from each other, as in the analogy of a cannon and cannonball. Energy is being supplied to the space between these two galaxies and not the galaxies themselves.
sarek

1
Wed 19 Nov, 2008 01:22 am
@validity,
validity wrote:
I am not saying that they would not work, I am questioning the use of the term KE for two sufficiently distant galaxies that the region of space between them is expanding, as the galaxies have not had energy given to them by an explosion that propelled them outwards from each other, as in the analogy of a cannon and cannonball. Energy is being supplied to the space between these two galaxies and not the galaxies themselves.

Let me see if I get this right.
Assume two galaxies a long way apart.

1. Because of gravity they will accelerate towards each other.
2. Because of the expansion of space they will be pushed apart.

Both effects would occur simultaneously. The actual redshift measured would be the result of 1+2.
sarek

1
Wed 19 Nov, 2008 01:29 am
@xris,
xris wrote:
Depends on what you call short...

Anything that does not go on forever is too small for me!

I see different numbers. But some theories even postulated a maximum 'size' of about 80% of our visible horizon. That would mean meeting ourselves after travelling only about 11 billion lightyears.
If the universe is bigger than the horizon we would probably be unable to directly detect topologically caused visual effects.
xris

1
Wed 19 Nov, 2008 04:45 am
@sarek,
It is the only valid theory in my mind that can explain all the problems that occure when looking at the BB universe...Im nothing like an expert just an ignorant observer of debates that for the most are too advanced for me. I would like for us to be able to try plotting our proposed position in a torus universe with our observed calculations and then see how it marries up with other observed problems..We cant theories on our desires for certain designed universe we must explore all possibilities..I dont think the universe will ever let us down in amazing us constantly..
0 Replies

sarek

1
Wed 19 Nov, 2008 05:05 am
@dkane75,
You are right when you note that current theories contain way too many unplausible constructions just to patch things up. I just don't like the sound of dark matter and even less that of dark energy. But I'm no expert either.
A Big Bang origin of the universe equates a singularity and that is often a sign something is amiss or not yet fully understood.

How does your view of a toroid universe relate to the latest ideas about multidimensional brane collisions? I assume some sort of 5D brane collision could lead to a 4D toroid configuration, but such mathematics is really somewhat over my head.
xris

1
Wed 19 Nov, 2008 06:00 am
@sarek,
There are so many new theories it blows my mind..In the end all we have is observations and theories should explain the observations not observations being ignored to suit theories..
0 Replies

validity

1
Wed 19 Nov, 2008 02:54 pm
@sarek,
sarek wrote:
Let me see if I get this right.
Assume two galaxies a long way apart.

1. Because of gravity they will accelerate towards each other.
2. Because of the expansion of space they will be pushed apart.

Both effects would occur simultaneously. The actual redshift measured would be the result of 1+2.

Do you mean by 1+2 occuring simultaneously, that the two galaxies appear stationary to one and another?
sarek

1
Wed 19 Nov, 2008 03:25 pm
@validity,
validity wrote:
Do you mean by 1+2 occuring simultaneously, that the two galaxies appear stationary to one and another?

No, its just an addition. Of vectors I suppose. But the two effects are almost never equal in size. Usually the expansive effect is greater but, for example in the case of M31 Andromeda, gravity prevails.
Two effects which for all intents and purposes are identical and differ only in having an opposite sign. Yet, one(gravity) can be described in terms of force(but also in terms of geometry) and the other(expansion) would be the result of spatial geometry.
An observer really can't differentiate between the principles at work.
I really can't shake the feeling that these two effects have a lot in common.
0 Replies

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