The Expansion of the False Vacuum
The inflationary theory proposes that the infant universe, or some small patch of it, was filled with a false vacuum. The repulsive gravitational force of the false vacuum would then have set off an extremely rapid expansion. In a period of time much shorter than we could ever imagine—perhaps 10 to the minus 37th power second—the region of false vacuum doubled in size. (The time span 10 to the minus 37th power second is a fraction of a second—written out as a decimal point followed by 36 zeros and the numeral 1.) Then in the same amount of time, it doubled again, and then again and again at least 100 times. This is called exponential expansion. In a twinkling, the universe became at least 10 to the 30th power (1 followed by 30 zeros) times larger than it had been. While any ordinary form of matter would have been diluted to a negligible density by such a gargantuan increase in volume, the peculiar properties of the false vacuum imply that its density of energy was unaffected by the expansion. The total energy in the false vacuum, therefore, grew enormously during the period of inflation.
The entire period of inflation lasted just a tiny fraction of a second because the false vacuum is unstable, just as the nuclei of radioactive elements are unstable. An unstable nucleus of uranium, for example, will decay by breaking up into a nucleus of thorium and a nucleus of helium. So, too, a false vacuum “decays” into other forms of matter. It converts its huge store of energy into a tremendously hot gas of essentially all the elementary particles. The gas is so hot that the particles cannot combine even to form protons or neutrons.