What Existed Before the Big Bang?

Here's a thought: What if our universe is but the offspring of another, older universe? Some astrophysicists speculate that this story is written in the relic radiation left over from the Big Bang: the cosmic microwave background (CMB).

Astronomers first observed the CMB in 1965, and it quickly created problems for the Big Bang theory -- problems that were subsequently addressed (for a while) in 1981 with the inflation theory. This theory entails an extremely rapid expansion of the universe in the first few moments of its existence. It also accounts for temperature and density fluctuations in the CMB, but dictates that those fluctuations should be uniform.

That's not the case. Recent mapping efforts actually suggest that the universe is lopsided, with more fluctuations in some areas than in others. Some cosmologists see this observation as supporting evidence that our universe "bubbled off" from a parent universe, in the words of California Institute of Technology researcher Adrienne Erickcek [source: Lintott]

In chaotic inflation theory, this concept goes even deeper: an endless progression of inflationary bubbles, each becoming a universe, and each of these birthing even more inflationary bubbles in an immeasurable multiverse [source: Jones].

Still other models revolve around the formation of the pre-Big Bang singularity itself. If you think of black holes as cosmic trash compactors, they stand as prime candidates for all that primordial compression, so our expanding universe could theoretically be the white hole output from a black hole in another universe. A white hole is a hypothetical body that acts in the opposite manner of a black hole, giving off serious energy and matter rather than sucking it in. Think of it as a cosmic exhaust valve. Some scientists propose that our universe may have been born inside a black hole, and every black hole in our own universe could each contain separate universes as well [source: Choi].

But some scientists think the universe started, not with a Big Bang, but with a Big Bounce.

Long ago, medieval religious philosophers in India taught that the universe goes through an endless cycle of creation and destruction, in which it evolves from an undifferentiated mass unto the complex reality the we see around us, before destroying itself and starting anew [source: Davis].

Some contemporary scientists have arrived at an idea with striking parallels. They believe that instead of a Big Bang, the universe expands and contracts in a cycle, bouncing back each time that it shrinks to a certain size. In the Big Bounce theory, each cycle would begin with a small, smooth universe that wouldn't be as tiny as the singularity. It would gradually expand, and become clumpier and more warped over time. Eventually, it would reach a point where it would start to collapse and gradually smooth itself out, as it shrank to the size of the starting point. Then, the cycle would begin anew [source: Wolchover].

For the Big Bounce idea to work, it has to find a way around the singularity theorems developed by British physicists Roger Penrose and Stephen Hawking, which suggest that a contracting universe would shrink all the way down to a singularity, in the fashion that a massive dying star eventually condenses to form a black hole. To do that, Big Bounce models depend upon the idea of negative energy counteracting gravity and reversing the collapse, so that that the universe and time-space would be driven apart again and again [source: Wolchover].

These cycles of contraction and expansion would repeat themselves, about once every trillion years [source: Taylor].

The Big Bounce would make a departure from western civilization's view of reality since St. Augustine, because it would recognize that time actually existed before the universe as we know it.

But whether it as a Big Bang or a Big Bounce, the question of what existed before our present universe remains an open question. Perhaps nothing. Perhaps another universe or a different version of our own. Perhaps a sea of universes, each with a different set of laws dictating its physical reality.

Explore the links on the next page to tackle other lofty, cosmological questions.

Originally Published: Jan 7, 2019