Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The History of the Universe
One of the consequences of General Relativity is that it prescribes the evolution of the universe. A few possible futures are possible, depending on how some parameters are chosen. These cosmological models regard the universe as one system with macroscopic quantities. Since the discovery that the universe is expanding in all directions (by the British physicist Edwin Hubble in 1929), the most popular models have been the ones that predict expansion of space-time from an initial singularity, the “Big Bang” (first speculated by the Belgian physicist Georges Lemaitre in 1927). Since a singularity is infinitely small, any cosmological model that wants to start from the very beginning must combine Relativity and Quantum Physics.
The story usually starts with an infinitely small universe, in which quantum fluctuations of the type predicted by Heisenberg's principle are not negligible, especially when the universe was a size smaller than the Planck length.
The fluctuations actually "created" the universe (space, time and matter) in a "Big Bang". Time slowly turned into space-time, giving rise to spatial dimensions. Space-time started expanding, the expansion that we still observe today. In a sense, there was no beginning of the universe: the "birth" of the universe is an illusion. There is no need to create the universe, because its creation is part of the universe itself. There is no real origin. The universe is self-contained, it does not require anything external to start it.
The universe had a small entropy at the Big Bang. The opposite (high entropy) is a state of thermal equilibrium with matter-energy distributed uniformly at a constant temperature (although with lumps of matter due to gravitation, as Roger Penrose showed,, and in fact the structures of highest entropy are the black holes).
Then the universe expanded. If the mass of the universe is big enough (and this is still being debated, but most cosmologists seem to believe so), then at some point the expansion will peak and it will reverse: the universe will contract all the way back into another singularity (the "Big Crunch"). At that point the same initial argument holds, which is likely to start another universe. For example, John Wheeler claims that the universe oscillates back and forth between a Big Bang and a Big Crunch. Each time the universe re-starts with randomly assigned values of the physical constants and laws.
Both the beginning and the end are singularities, which means that the laws of Physics break down. The new universe can have no memory of the old universe, except for a higher entropy (assuming that at least that law is conserved through all these singularities), which implies a longer cycle of expansion and contraction (according to Richard Tolman's calculations).
Some scientists believe that they can remove the singularities. In particular, Hawking has proposed a model in which Time is unbounded but finite, and therefore it is not created in the Big Bang even if the universe today has a finite age. (According to Einstein, space is also finite yet unbounded). In his model, Time emerges gradually from space and there is no first moment.
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