The Big Bang is all but dead and we do not yet know what will replace it.
There are those who will tell you that Cosmology — the study of the Universe entire — has become an exact science. They will tell you that this grand and all embracing field has, in the last 50 years, moved from the realms of philosophical speculation into the purest domains of science via exacting confrontations between theoretical models and high-resolution data. You should know that they are right.
For the first time in the long march of human thinking we are now, finally, able to construct a detailed and verifiable account of cosmic history.
So when I tell you that Big Bang is dead I do not mean the story that begins with a Universe far hotter and far denser than what we see today. I do not mean the story of a Universe expanding, of matter cooling and congealing over billions of years into stars and galaxies. That story, the scientific narrative of cosmic evolution over the last 13.7 billion years is doing just fine. That story is, for all intents and purposes, secure.
It’s the beginning that has fallen. It is genesis that stands ready to be replaced.
The singular and all-important moment of creation at the beginning of the Big Bang — the beginning of time and existence — has become precarious and is poised to be swept aside. In other words it’s the Bang in the Big Bang that we humans, in our endless quest to understand the world, are ready to abandon. That single moment of creation with no before is almost exhausted, done in by the very precision of the science which gave it's conception a measure of reality.
Now it appears that science is ready to go beyond, and before, the Big Bang. Cosmology is waiting at the precipice of its next great revolution. The only question is where, or better yet “when,” do we go from here? We are ending the beginning and beginning down another path.
There are different reasons for this push backward. I am in the midst of writing a book on the subject (almost done… almost… done) so I will be blogging on this topic more as time goes on. Today, I will leave you with two terms which sum up the move away from a single moment of creation: Inflationary Cosmology and Quantum Gravity.
Inflationary Cosmology is a major addition to standard Big Bang theory. It emerged in 1980s to solve a number of paradoxes that arose in both particle physics and cosmology. Inflation imagines a tiny sliver of the Universe undergoing expansion on steroids at the barest instant after the Big Bang. Inflation makes all we see nothing more than a bubble in a much larger, unknown Universe. In the Eternal Inflation versions of the model, the process goes on and on with no beginning and no end — bubble universes are always being born and are always “dying”. No single Big Bang need exist and hence no beginning of cosmic time.
Quantum Gravity is the name physicists give to their holy of holies — a theory uniting Einstein’s description of Space-Time and the Quantum description of the microworld. String Theory makes a claim to this throne but there are other equally interesting ideas like Loop Quantum Gravity. What they all share is the desire to climb within that first moment of creation, the singularity at t = 0 when the Universe and time just began. From these explorations new cosmological ideas like Cyclic Universes emerge: Big Bangs followed by Big Crunches or Big Bangs as collisions between hyperdimensional sheets of reality. There are many ideas coming from research on Quantum Gravity theories, many ways of avoiding a single moment of “Let There Be Light.”
Most scientists were never happy with a comsic beginning. It was too strange, like firing up the engine on God’s Porsche. Now there seem to be many routes to before but only time (and ultimately data) will tell us what to do with problem of time’s beginning.