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Author Topic:   Hawking's Information Paradox solution
dogrelata
Member (Idle past 5341 days)
Posts: 201
From: Scotland
Joined: 08-04-2006


Message 16 of 42 (371972)
12-24-2006 10:25 AM
Reply to: Message 7 by cavediver
11-26-2006 11:26 AM


Re: Explanation please?
cavediver writes:
As we start to consider quantum gravity, various possibilities are introduced. One of these is the idea of baby universe: branches of space-time separating off from the trunk space-time via black-holes and similar phenomena. One of Hawking's proposed solutions to the information problem used baby universes (dating back to the 80s). These are not alternate or "other" universes as such. Imagine a treee as the whole of our space-time. Take a horizontal slice through the tree at a particular height, and that gives a picture of how we consider our universe with thes ebaby universes: a central area (the x-section of the trunk) and lots of smaller distinct isolated areas (x-sections of the branches). It looks like lots of separate universes. But when you look at the whole tree, you realise that it is all one big connected space-time.
I’ll bet you guys must dread the non-scientists wandering in here with our laymen’s lack of deep underlying knowledge, but part of the fun of this place is getting the chance to ”rub shoulders’ with some very knowledgeable people
This idea of baby universes is one that I’ve often wondered about. The idea that each black hole in this universe might at some point lead to a new baby universe, and that our own universe originated from a black hole within a larger universe, which in turn may have originated similarly, etc. Okay, so there are some pretty serious problems regarding calculations of mass, etc, which requires this layman to develop his own scientific theory, i.e. it would only be possible to measure the mass of any given universe and it’s descendants, the mass of ”parent’ universes being undetectable. In the tree analogy, the ”weight’ of any branch would include all sub-branches, but not the branch or trunk from which it has sprung.
But when I use the term ”undetectable’ in the previous paragraph, there is one other thing I wonder about.
Once or twice I’ve seen an analogy used to try to describe the warping of the fabric of space-time as an object moves through it. The analogy is of a ball bearing rolling over a membrane. As it does so, it stretches and ”warps’ the membrane. Fair enough, it helps me to visualise what is happening, but I have a problem if the analogy is attempting to convey more than the 'visual' effect.
The problem is that the ”warping’ of the membrane is caused by the gravitational pull of the earth acting upon the ball bearing. For the ball bearing analogy to work, does it mean that there must be some ”external’ gravitational force acting upon the object travelling through space-time to cause the ”warping’? If so, might this gravitational force not originate from other ”branches of the tree’ that we are otherwise unable to detect because they exist outside of our universe or its sub-branches?
Okay. I’m going to go now, and will not be offended by any flak that comes my way as a result of my naivety and lack of understanding.

This message is a reply to:
 Message 7 by cavediver, posted 11-26-2006 11:26 AM cavediver has replied

Replies to this message:
 Message 17 by Son Goku, posted 12-24-2006 3:21 PM dogrelata has replied
 Message 19 by cavediver, posted 12-25-2006 8:02 PM dogrelata has replied

  
dogrelata
Member (Idle past 5341 days)
Posts: 201
From: Scotland
Joined: 08-04-2006


Message 18 of 42 (372206)
12-25-2006 5:03 PM
Reply to: Message 17 by Son Goku
12-24-2006 3:21 PM


Re: Gravity as warping.
Son Goku writes:
Gravity is nothing more than particles following straight lines in spacetime. This is why two objects of different masses fall at the same speed, following a straight line doesn't depend on your weight.
Cheers Son.
I’m not sure if this helps me understand whether the ball bearing/membrane analogy is a good one though. In the analogy, the warping of the membrane will be mainly down to the earth’s gravitational force acting upon the bearing, causing it to warp the membrane. If you were to take the bearing to a part of the universe where the gravitational forces were much less strong, presumably the warping effect would be much less pronounced.
The question I’m trying to ask is, how certain are we that the warping we observe in the fabric of space is entirely due to the gravitational forces acting upon it by the objects travelling through it?
And whilst I’m on a roll with crazy, nave questions, I’d like to ask one more.
As far as I understand it, science believes that the rate of expansion of the universe is still accelerating and there are those who have a problem with this, as they believe it ought not to be, given their understanding of the processes involved. So the question is, if there were external gravitational forces acting upon our universe, might that be a possible cause of the continued acceleration?

This message is a reply to:
 Message 17 by Son Goku, posted 12-24-2006 3:21 PM Son Goku has not replied

  
dogrelata
Member (Idle past 5341 days)
Posts: 201
From: Scotland
Joined: 08-04-2006


Message 20 of 42 (372260)
12-26-2006 7:51 AM
Reply to: Message 19 by cavediver
12-25-2006 8:02 PM


Re: Explanation please?
cavediver writes:
Again, gravitational forces are our naive interpretation of the warping. Spae-time is not warped by 'gravitational forces'. Mass, energy, and momentum (and most importantly space-time curvature) all generate space-time curvature. Oh, also a cosmological constant, which is important for the accelerating Universe.
So are we saying that the warping of space-time is not caused solely by mass/energy? That space-time is ”naturally’ warped? Or is space-time comprised of mass/energy, which causes it to warp itself? Apologies for all the questions, but I’d always been led to believe that the warping was due to gravitational forces.
Finally, isn’t the cosmological constant still a highly contentious issue?

This message is a reply to:
 Message 19 by cavediver, posted 12-25-2006 8:02 PM cavediver has replied

Replies to this message:
 Message 21 by fallacycop, posted 12-26-2006 8:15 AM dogrelata has not replied
 Message 22 by Son Goku, posted 12-26-2006 9:21 AM dogrelata has not replied
 Message 23 by cavediver, posted 12-26-2006 12:17 PM dogrelata has not replied

  
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