．Well, that IS logical. But actually what happened during the Big Bang? What is all the scientists talking about?・
．Big Bang, the process involves the creation of the world, matter, radiation and energy.・
The
ultimate instant that physics allows us to speculate about takes us back even
closer to the big bang. Imagine a moment so early and a density so high that
the gravitational stresses were capable of tearing apart the vacuum. At a later
era, the nuclear and electromagnetic forces created pairs of elementary particles.
If gravitational forces were sufficiently great, they also would have been capable
of creating pairs of particles from the vacuum. In other words, at the moment
of singularity, space-time was essentially disrupted by the gravitational forces.
To estimate the earliest instant that is amenable to our study, we must make use of the modern theory of physics of the ultimate structure of matter, quantum mechanics. According to Heisenberg・s uncertainty principle, we can never precisely pinpoint the location of any elementary particle. Atomic nuclei and electrons lose their individual identity and acquire a wavelike nature on a scale known as the Compton wavelength. We can no longer locate elementary particles at a particular point of space; now we can locate them only in a particular region, and individual particles become indistinguishable. The dimension of this region of uncertainty is the wavelength of the particle. The larger the mass, the smaller the wavelength. Even macroscopic objects possess their wavelength of uncertainty: you, the computer, may spontaneously go through the floor, given a long enough period of time, a time that is much longer than the age of the universe. An elementary particle, however, manifests this uncertainty on a very short time scale.
Let
us now consider an era so early that the entire observable universe was contained
within its own Compton wavelength. This is the ultimate limit of our theory
of gravity, where uncertainty reigns supreme. At this instant, known as the
Planck time, only 10-43 second after the singularity, all
the matter we now see in the universe, comprising some millions of galaxies,
was compressed within a sphere of radius equal to one-hundredth of a centimeter,
the size of the point of a needle. At this moment, the extent of the universe
visible to any hypothetical observer was only 10-33 centimeter in
diameter, far smaller even than an atomic nucleus.
If all the atoms in the present stars and galaxies were spread uniformly throughout space, there would be about one atom of hydrogen per cubic meter of space. In addition, there would be perhaps one-tenth as much helium. All the heavier atoms collectively amount to less than 1 percent of the number of hydrogen atoms. In the early universe, the density was very much higher.
One
second after the bang, the density had dropped to 10 kilograms per cubic centimeter.
(Ordinary rocks have a density of a few grams per cubic centimeter.) At the
Planck time, the density approached 1090 kilograms per cubic centimeter.
These physical conditions are so extreme that it seems entirely appropriate
to regard the Planck time as the moment of creation of the universe.