Comments uniquely my own will appear in [square brackets].
Part 2
The inflationary version came about when Alan Guth was looking for the solution to the magnetic monopole problem. In 1931 Paul Dirac showed that magnetic monopoles are consistent with quantum theory and that it gives a specific prediction of the strength of the magnetic charge. In 1974 Gerard 't Hooft and Alexander Polyakov independently discovered that some modern particle theories imply the existence of magnetic monopoles. A modern Grand Unified Theory (GUT) contains monopoles with masses as heavy as 1017 times as heavy as a proton. In 1979 Guth made what he called a crude estimate of the monopole density: There should be about 10,000 times more monopoles and antimonopoles that have not yet annihilated as protons or neutrons. Later that year John Preskill concluded that they would be about the same number. Even with that lower number, he argued that the universe could be no more than 1200 years old due to the gravitational attraction from the greater mass if monopoles were numbered that high.
Guth, working with Henry Tye, theorized that inflation is accompanied by supercooling of a delayed phase transition. The supercooling would ward off the glut of monopole production. Supercooling is explained in the sense of Higgs Fields (theoretical fields, the nature of which that can not be deduced from known physics). The energy density for Higgs fields is shown as a 3-dimensional graph that looks like a Mexican hat with the sides higher than the middle. The base of the hat when sitting on a table has the points of contact with the table defined as the vacuum circle. The coordinates on the table top are represented by Higgs field A and Higgs field B. For the case with a large amount of supercooling, the center of the hat is dented down somewhat. A point in that center corresponds to the state called the false vacuum, in which both Higgs fields have a zero value. This state has a high energy density, but is classically stable. The false vacuum leads to a state of gravitational repulsion, which causes the universe to expand exponentially. Cosmological theories invoke 100 or more doublings – until the false vacuum decays by quantum tunneling.
In 1981 inflation had a problem: how it could end. Guth had concluded that the bubbles of the phase transition would not percolate. Andre D. Linde at the Lebedev Physical Institute in Moscow and the team of Paul Steinhardt and Andreas Albrecht at the University of Pennsylvania independently concluded that the observable part of the universe is contained inside one bubble. The old inflation theory had to be abandoned. Linde went on developing a new inflationary theory while Steinhardt proposed a new version of the 'Mexican hat' with a gently sloping middle section. This would allow inflation to exit gracefully without tunneling.
In a 3-week seminar in 1982, Stephen Hawking, Guth, and several other physicists could not agree on the math, so each modified their assumptions and recalculated until they had a concensus. For the very attractive GUT of Georgi and Glashow, the predicted amplitude was 5 or 6 orders of magnitude too large, requiring the Higgs fields to be 1013 times flatter. The Higgs fields needed to be where they were for spontaneous symmetry breaking to occur, so they invented a new field called the Inflaton field (notice the spelling). In 1985 the failure of the Irvine-Michigan-Brookhaven detector to find a proton decay, spelled the end of the simplest GUT, the Georgi and Glashow GUT. [Occam's razor missed here.]
The new inflation theory explains the clumping of galaxies that is seen today. The COBE data showed the non-uniformity data that matched the predictions of quantum fluctuations from inflation.
Gravitational potential energy increases with distance. If we give the energy stored in the gravitational field a negative number, then it can cancel out all of the other energy, resulting in the total energy of the universe being zero! With the classical BB theory, the universe must start out with 10 billion times the total mass in the visible universe today.
To create an inflationary universe you only need one ingredient: a region of false vacuum (maybe as small as 10-26 centimeters across). This size would have a mass of about an ounce (25 grams), but would have a density of 1080 grams per cubic centimeter. If the mass of the entire observed universe were compressed to false vacuum density, it would fit in a volume smaller than an atom. [There is a lot of difference between this and nothing.]
A region of false vacuum will grow forever: once inflation begins, it never stops, producing an infinite number of "pocket" universes at an ever-increasing rate. A fractal pattern is created. [This would get out of control fast! God would never create anything that would get out of control.] The possibility of attaining an expansion velocity fast enough for universe creation runs into conflict with a theorem proved in 1965 by Roger Penrose. The interpretation of that theorem states that an inflationary universe must begin with a singularity with the characteristics of a white hole. The Penrose theorem implies that a false vacuum cannot be caused to expand fast enough to produce a universe.
To solve this problem, a lot of theories have been produced. In 1982, Alexander Vilenkin proposed an extension of an idea by Edward Tyron, that the universe was created by a quantum fluctuation from literally nothing. [Quantum fluctuations come from a vacuum. Without a vacuum, how would this be possible?] The vacuum is seen as enormously complicated, with nonzero values for the Higgs fields, and particle-antiparticle pairs popping in and out of existence. No one knows how to calculate the energy density of a vacuum. Particle physicists' estimates are about 10120 times larger than a value consistent with observations!
Very shortly after new inflation was proposed, Linde proposed another variant called chaotic inflation. In the late 1980s, Steinhardt and Daile La invented another called extended inflation. Before 1998 there were at least 50 versions that had been named and studied including double, triple, hybrid, mutated hybrid, tilted hybrid, hyperextended, and supernatural. Cosmologists have studied inflation that is gravity driven, spin driven, and vector field driven; also warm, soft, tepid, and natural.
(Adapted from The Inflationary Universe by Alan Guth, copyright 1997)
Near the end of his book (p. 276) he made this statement: "If the creation of the universe can be described as a quantum process, we would be left with one deep mystery of existence: What is it that determined the laws of physics?"
In part 3, I will talk about supernova observations and the cosmological constant.
Is the big bang theory in chaos? Maybe we need to get the actor Jeff Goldblum to help us out. We had an actor for President once!
State of the Big Bang Theory - part 2
Re: State of the Big Bang Theory - part 2
