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.