|How Do We Know the Universe Hasn’t Existed Eternally?
Posted: 11 Sep 2013 06:00 AM PDT
Post Author: Bill Pratt
For those of you who look to science to answer every question, cosmologists are pretty unanimous in agreeing that our universe is not eternal, and in fact begun about 14 billion years ago. You may not like this answer, and so go running toward alternative cosmologies to escape the standard big bang model of the universe. Unfortunately, there is no salvation there either.
As summarized nicely on the Wintery Knight blog, “The Borde-Guth-Vilenkin [theorem] shows that every universe that expands must have a space-time boundary in the past. That means that no expanding universe, no matter what the model, can be eternal into the past. Even speculative alternative cosmologies do not escape the need for a beginning.”
So it would appear that science is no help to those who want to desperately cling to an eternal universe. What about philosophy?
The dominant ancient metaphysical traditions have also demonstrated why the physical universe cannot be eternal. Here we quote from Edward Feser in an article he wrote for First Things:
In general, classical philosophical theology argues for the existence of a first cause of the world—a cause that does not merely happen not to have a cause of its own but that (unlike everything else that exists) in principle does not require one. Nothing else can provide an ultimate explanation of the world.
For Aristotle and Thomas Aquinas, for example, things in the world can change only if there is something that changes or actualizes everything else without the need (or indeed even the possibility) of its being actualized itself, precisely because it is already “pure actuality.” Change requires an unchangeable changer or unmovable mover.
Feser goes on to consider other great thinkers of the past:
For Neoplatonists, everything made up of parts can be explained only by reference to something that combines the parts. Accordingly, the ultimate explanation of things must be utterly simple and therefore without the need or even the possibility of being assembled into being by something else. Plotinus called this “the One.” For Leibniz, the existence of anything that is in any way contingent can be explained only by its origin in an absolutely necessary being.
But why can’t the first cause, the necessary being, “the One,” be the universe itself instead of God? What is the difference between an eternal Creator and an eternal universe?
The difference, as the reader of Aristotle or Aquinas knows, is that the universe changes while the unmoved mover does not, or, as the Neoplatonist can tell you, that the universe is made up of parts while its source is absolutely one; or, as Leibniz could tell you, that the universe is contingent and God absolutely necessary. There is thus a principled reason for regarding God rather than the universe as the terminus of explanation.
So, positing the universe as an eternally existing thing that is the cause of everything else both collides with modern science and with classical metaphysics. I happen to think the metaphysical arguments are stronger, but maybe you prefer the science. Either way, it don’t look good for an eternal universe.
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