Most scientists currently think the cosmological Big Bang Theory is valid. In this view, the universe, including time and space, began with a massive explosion at an infinitesimal point. Some people wonder why this happened when it did. What sort of ticking clock initiated the event? But this is a meaningless question. Time itself began at the Big Bang. To hold otherwise is like trying to go north of the North Pole.
The imminent astronomer Fred Hoyle formulated the Steady-State Theory, but it was overthrown by observational evidence including lack of nearby quasars and presence of background microwave radiation left over from the Big Bang.
Observations including spectroscopic evidence confirms the Big Bang Theory. It is a fact that the universe is rapidly expanding. The inevitable conclusion is that it had a central point of origin and all matter was at one time concentrated at that point.
Cosmic inflation is the name given to a brief, rapid expansion of the universe following its inception at the Big Bang. The accelerated growth is currently believed to have happened only between 10-36 and 10-32 seconds following the eruption of the singularity. During this tiny fraction of a second, the precondition for all matter and energy that would ever exist expanded at greater than the speed of light from a point in space the size of a proton to a globe whose radius was equal to that of a grapefruit. Following this inflationary period, the sphere containing everything resumed its prior slower albeit enormous expansion rate.
Alan Guth (born February 27, 1947) developed the idea of cosmic inflation at Cornell University in 1979. Today the theory is widely accepted. All of this seems fanciful in the extreme, but it is in accord with current thinking and in fact is required in the light of well-established and empirically backed theory.
Since the acceptance of Einstein’s Relativity Theories, we have become accustomed to believing that motion faster than the speed of light is impossible, but if you do the mathematics, it seems to be required for cosmic inflation. This further supports the notion that the motion did not happen through space. Instead, during the inflationary period, the time/space reference frame itself was expanding.
So how do we even know that this period of inflation was real? There are three facts, confirmed by observation, that point in this direction:
1. The universe seems to be isotropic, meaning that it is the same in all directions.
2. Cosmic background microwave radiation is evenly distributed.
3. No magnetic monopoles have been observed.
The fact is that the universe has just the right amount of structure, such as galactic differentiation, to have arisen from a past that contained the inflationary period described by theoreticians. Without the inflationary period, the universe would have exploded into a vastly different conglomeration due to unchecked amplification of perturbations that would have been the result of early quantum granulation.
An exact mechanism within particle physics theory for the inflationary period remains unknown, but predictions based on its existence correspond to our observation of the early universe, made possible by time-delayed images of distant objects. It is surmised that there was a field that caused inflation, and the name we have given it is inflaton. Beyond that, details remain hidden. Theoreticians have stated that a more fully realized String Theory will shed additional light on this mysterious event.
How will the universe end or will there be an end? The jury is out on that question, but currently a few alternatives have emerged. Yet-to-be-determined answers to some basic questions will show which of these alternatives is operative.
In the mid-twentieth century the now obsolete Steady-State Theory was widely held. It contended that the universe will continue to expand indefinitely and that new matter is continuously forming so the state of affairs remains unchanging. In this view, the universe has no beginning or end.
The theory was overthrown in the 1960s. Observations of quasars showed they were apparent only at great distances. Because of the time light takes to travel distances measured in light years, it follows that quasars existed only at an early epoch. If the Steady-State Theory were true, they would be continuously created everywhere including nearby, which is not the case.
The non-steady-state expanding universe may or may not imply the universe will end at a definite point in time, depending upon whether the Many-Worlds Interpretation is correct. If that theory is true, our particular universe may end but the overall wave function will not collapse as in the Copenhagen Interpretation of quantum mechanics, and reality will continue.
If the Many-World Theory is not true, two alternatives remain, depending on the as-yet unknown density of everything, including dark matter and dark energy. One of the alternatives is that the universe will continue to expand indefinitely, in which case it will endure what is known as the Heat Death. Because of the inevitable rise in entropy, matter and energy will lose the structure and detail necessary to support information, which includes any form of life. Temperature will drop.
The other alternative, presupposing a greater density, is that the current expansion of the universe will ultimately slow and reverse, ending in what has been called the Big Crunch. In this narrative, gravity will predominate and all matter will contract to a single point in space, consolidating into a singularity as existed at the Big Bang. If this happens, it may be that another primordial explosion perhaps will give rise once again to billions of galaxies, stars, planets and life.
In any event, Heat Death or Big Crunch, we won’t have to worry about it for awhile, possibly for billions of times the present age of the universe. If the Many-Worlds Interpretation of quantum physics is valid, as asserted by Stephen Hawking and other leading theoreticians, there may yet be an ultimate reprieve.
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