These are excerpts and elaborations from my book "The Nature of Consciousness"
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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. Back to the beginning of the chapter "The New Physics" | Back to the index of all chapters |
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