The following ideas are primarily mine alone, the good, the bad and the ugly, albeit based on and influenced by reading multi volumes of tomes in modern cosmology. However, I’m also quite sure that numerous others have quite independently thought somewhat similar, if not exact, thoughts as well. Therefore, I’ll take no credit for being right, if I don’t get blamed for being wrong!
IN THE BEGINNING (QUANTAM COSMOLOGY)
The origin of the Universe (the Big Bang) was a quantum event because the initial size of our Universe was such that quantum effects dominated. Quantum theory has to apply to cosmology (or astrophysics) anytime the tiny world where quantum effects need to be considered apply, such as in black hole singularities – or when the Universe itself was tiny, such as at the time of the Big Bang, or a Big Crunch – when things become singularities. Fortunately, there is such a thing as quantum time (the smallest time length possible) and quantum length (hence volume) – the smallest length (hence volume possible).
Assuming that the Universe will ultimately contract into a Big Crunch, what will happen? Well, as one gets ever closer to the Big Crunch, density increases (but will not, can not, become infinite) and temperature increases (but again, not infinitely so) and the volume of space decreases (but will never become infinitely tiny) and time just keeps ticking on. Further, we know there are lots of black holes out in the cosmos; both small and massive (such as exists at the centre of our galaxy). As the Universe contracts, these black holes will get closer and closer not only to each other, but to the rest of non black hole stuff as well. Ultimately, all the non black hole stuff will get sucked into existing black holes as the Universe shrinks and matter’s density increases. Of course large black holes will also suck in smaller black holes, until ultimately, at the time approaching Big Crunch, there will be one ultimate/universal black hole containing all that was. Then what happens? The conditions inside a black hole are still unknown, beyond the equations of current physics, but whatever parameters are present, infinities aren’t among them (which might put me at odds with most astrophysicists). My reasoning is that no matter what, there’s only a finite amount of stuff comprising the universal black hole. Squeezed into a tiny area, the density will be extreme, but not infinitely so. The volume will be tiny, but not infinitely so. That is because there is an ultimate limit to how small length (hence volume) can get. The smallest possible length is known as Planck length and anything less than that space ceases to exist. Planck length is 1.6 x 10 to the minus 35 meters. Gravity might be so intense that not even light can escape, but it doesn’t take an infinite amount of gravity to do that. And there can’t be a time equals zero, either at the beginning (Big Bang) or at the end (Big Crunch). Because time exists in discrete quantum units (Planck-Wheeler time units as noted above), one must go from a minus one (contracting phase) time unit directly to a plus one (expanding) time unit, as there can be no time unit where time equals zero. In other words, you go from a Big Crunch directly to a Big Bang, expansion to contraction, endlessly cycling. Or, the universal black hole sucking in all matter and energy (Big Crunch) turns inside out and becomes a universal white hole (Big Bang) spewing out stuff (matter and energy). That’s one possibility.
That’s sort of akin to having four cars approach an intersection, on each from the north, south, east and west. If each car is one kilometre from the intersection, and each car is travelling at say 50 kilometres per hour, then it is clear this contraction of automobiles will result in a Big Crunch. However, it might be difficult to then go to an automobile expansion as the cars will be a wreck.
The other possibility is that it might be unrealistic to expect in a contracting Universe that each and every bit and piece will meet at exactly the same point in time and space. Using our car analogy, what if each car was one kilometre away from the intersection, but say the north car was going 46 kilometres per hour, the east car 48 kilometres per hour, the south car 50 kilometres per hour, and the west car 52 kilometres per hour. Then, we can go directly from automobile contraction to automobile expansion as each car passes through the intersection while only having near misses with the other vehicles.
Next blog I give another (and probably more accurate) point of view.
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