Chris wrote:Aug 25
Actually, it is more accurate to consider the surface of the observable universe to be t=0. (1)The moment of the Big Bang does not lie outside the observable Universe, only outside that part which we can observe with electromagnetic radiation.
(2)The CMBR is the surface of that sphere, which is slightly smaller than the observable universe. We will be able to see beyond the CMBR, to an even earlier state of the Universe, using gravity waves rather than EM.
There are no bubbles. Every point in the Universe simply has its own observable universe. There's nothing special about any of them... in fact, they don't even have any physical reality. (3)Imagine a bunch of people standing around in a big field at night with lanterns. Each of them has his own observable world, but this has no physical meaning to the entire field at all
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No argument. But what if, there were were several big adjacent fields, each separated by tall walls but each adjoining doors. The opening and closing of these doors give different meanings to the adjacent fields.
Chris wrote:Aug 26
You misunderstand the theory. (4)First of all, we are not limited by our telescope technology to seeing beyond the CMBR. The limitation to seeing beyond in EM is fundamental: before this time, the Universe was opaque to photons. No optical telescope will ever be created that can see beyond the CMBR because there is no light coming from beyond.
Beyond the CMBR, space/time has expanded beyond the limits of any man made instruments. Or are we to assume the concept of space/time does not apply beyond the CMBR? Your statements in (2, Augs 25) and (4, Aug 26) appear to be inconsistent.
There is no physical thing "the observable universe". It is as I suggested before with my lantern analogy. (5)If the Universe is a big field, each observer's visible universe is simply the area he can see in the circle of light cast by his lantern. These circles were not created by the Universe.
Your statement is also true of the CMBR. The Universe did not create the CMBR, but for now the CMBR defines the limit of the "observable universe".
(6)The Universe is not a sphere; it did not expand spherically from the Big Bang. (7)Observable universes are spherical cross sections of the Universe as a whole. They represent nothing more than the parts of the Universe that an observer can see because they were moving at less than c with respect to that observer when they emitted their photons, gravity waves, or anything else that might be carrying information.
This appears to be in contradiction to your previous statement (see # 2).
The Universe is no different on the outside of the observable universe than it is on the inside. It isn't hotter, or colder, or younger, or older. The Universe is the same everywhere. If you could travel to the edge of the observable universe, you would be no closer to t=0, you wouldn't see anything unusual. You'd be in a new observable universe, of course, with its own CMBR- exactly as far from you there as it is from us here.
Let me rephrase my original question. Where is time=0 relative to the CMBR and t=now? Is it at, before or after CMBR? Again, I would to refer to your Aug 25 (marked #1).
I think you may be conflating a [very hypothetical] multiverse theory, where different universes were created, of which one is ours, with the idea of the observable universe which is not describable as bubbles, and isn't even a real thing.
Guilty as charge. Further, I am expanding on it and saying that over time, some of these multiverses may have combined (and may be combining now and in the future) similar to how galaxy structures form.