What Happened Before the Big Bang?
Cosmologist Alex Vilenkin does the math to show that the universe indeed had a starting point
By now, there’s scientific consensus that our universe exploded into existence almost 14 billion years ago in an event known as the Big Bang. But that theory raises more questions about the universe’s origins than it answers, including the most basic one: what happened
before the Big Bang? Some cosmologists have argued that a universe could have no beginning, but simply always was.
In 2003, Tufts cosmologist Alexander Vilenkin and his colleagues, Arvind Borde, now a senior professor of mathematics at Long Island University, and Alan Guth, a professor of physics at MIT, proved a mathematical theorem showing that, under very general assumptions, the universe must, in fact, have had a beginning.
Since that discovery, others in the field have countered with alternate theories describing other kinds of universes where the Borde-Guth-Vilenkin Theorem, as it is called, would not apply. Vilenkin, a professor of physics and astronomy, and graduate student Audrey Mithani, G15, used mathematics to examine three potential logistical loopholes in the 2003 theorem, strengthening their original premise that the universe did, in fact, begin
Q: Some people claim your work proves the existence of God, or at least of a divine moment of creation. What do you think?
Alexander Vilenkin: I don’t think it proves anything one way or another.
I went to a meeting of some theologians and cosmologists. Basically, I realized these theologians have the same problem with God. What was He doing before He created the universe? Why did He suddenly decide to create the universe?
For many physicists, the beginning of the universe is uncomfortable, because it suggests that something must have caused the beginning, that there should be some cause outside the universe. In fact, we now have models where that’s not necessary—the universe spontaneously appears, quantum mechanically.
In quantum physics, events do not necessarily have a cause, just some probability.
As such, there is some probability for the universe to pop out of “nothing.” You can find the relative probability for it to be this size or that size and have various properties, but there will not be a particular cause for any of it, just probabilities.
I say “nothing” in quotations because the nothing that we were referring to here is the absence of matter, space and time. That is as close to nothing as you can get, but what is still required here is the laws of physics. So the laws of physics should still be there, and they are definitely not nothing.
An exploration with a mathematician about what precedes the Big Bang
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