These are excerpts and elaborations from my book "The Nature of Consciousness"
Inflation:
Before Time In 1965 the US astronomers Arno Penzias and Robert Wilson accidentally discovered the cosmic microwave background radiation ("A Measurement Of Excess Antenna Temperature At 4080 Mc/s"). This was the remnant of the Big Bang, still travelling across the universe. What puzzled physicist was that it was uniform (constant throughout the universe). This caused two problems. First of all, according to Relativity, nothing can travel faster than light, hence it was impossible for distant regions of the universe to communicate and achieve equilibrium of any sort. Secondly, the universe that we observe is not uniform but has lots of irregularities that we call "galaxies" and the likes. This "inflationary" model, proposed by Alan Guth ("The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems", 1980) expanding on the 1948 theory of cosmogenesis by the Ukrainian physicist George Gamow (who, in turn, developed a 1927 idea by the Belgian physicist Georges Lemaitre), assumes that the universe began its life in a vacuum-like state containing some homogeneous classical fields but no particles (no matter as we know it). Then it expanded exponentially (that's the "inflation") and the vacuum-like state decayed into particles. The structure of the universe was created in the first fraction of a second. Guth's model is based on the existence of scalar fields. A scalar field is one caused by a quantity which is purely numerical, such as temperature or household income. Gravitational and electromagnetic fields, in contrast, also point in a specific direction, and are therefore "vector" fields. Vector fields are perceived because they exert some force on the things they touch, but scalar fields are virtually invisible. Nonetheless, scalar fields play, for example, a fundamental role in unified theories of the weak, strong and electromagnetic interactions. Like all fields, scalar fields carry energy. Guth assumed that in the early stage of the universe a scalar field provided a lot of energy to empty space. This energy produced the expansion, which for a while occurred at a constant rate, thereby causing an exponential growth. Guth's model solved a few historical problems of cosmology: the "primordial monopole" problem (grand unified theories predict the existence of magnetic monopoles); the "flatness" problem (why the universe is so flat, i.e. why the curvature of space is so small); and the "horizon" problem (how causally disconnected regions of the universe can have started their expansion simultaneously). It does not account for dark matter and energy (for the fact that the exponential inflation slowed down dramatically to what it is now, a thousand times less). In 1981, at the Pontifical Academy of Sciences in Rome, Stephen Hawking and James Hartle presented the "no-boundary" theory according to which the universe would be shaped like a shuttlecock; and they later derived a wave function for this kind of universe, showing that it correctly predicts our flat and expanding universe. In their model, time didn't exist at the beginning: it "emerged" later on from pure space. While everybody agrees that the universe is expanding, not everybody agrees on what that means. In the quest for an explanation of dark matter and dark energy, the British physicist Geoffrey Burbidge, the British physicist Fred Hoyle and the Indian physicist Jayant Narlikar developed the "Quasi Steady State Cosmology" (reprised in the "Cyclic Universe Theory" by the US physicist Paul Steinhardt and the British physicist Neil Turok), according to which there is no "Big Bang" to begin with, and there will be no "Big Crunh" to end with. Space and time existed ever since and will exist forever. There is no beginning nor end. The evolution of the universe is due to a series of "bangs" (explosive expansions) and "crunches" (contractions). The Big Bang that we observe today with the most powerful detectors of microwave radiations (first detected in 1964) is simply one of the many expansions following one of the many contractions. Each phase may last a trillion years, and therefore be undetected by human instruments. Burbidge doubts black holes, quasars and the cosmic radiation.
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