Humans have spent thousands of years trying to explain the origin of the universe through mythology, religion, and science. So for this week’s Cosmically Curious, we checked with Nicole Gugliucci from Saint Anselm College to talk about how modern physicists tackle the ultimate origin story.
The Big Bang.
"We look around us in the sky, and we see that galaxies are generally moving away from us," Gugliucci explains. "If you run back the clock, we must have all been at one point at some time or another. That transition is what we call the Big Bang."
But that raises the ultimate follow-up: What was going on before the Big Bang?
The Big Bang created time and space itself. How do you talk about a "before" when time didn't even exist yet? To even begin to understand how that works, physicists have to marry two incredibly different concepts:
- How the universe works around massive gravitational forces (explained by Einstein's general relativity).
- How the universe works at unimaginably small scales (explained by quantum mechanics).
The problem? When you try to put them together, the math completely breaks. They just don't play well together.
Because the standard models break down at the starting line of the universe, theoretical physicists have to get creative. Enter a concept you might have heard of in passing: loop quantum gravity.
So, what exactly is it?
"It models gravity using Einstein’s general relativity alongside quantum physics, and it treats spacetime as being composed of finite loops — kind of like making fabric," says Gugliucci.
This is totally bizarre to think about, because we usually visualize spacetime as a smooth, stretchy sheet of fabric. Instead, loop quantum gravity suggests it's woven out of tiny, discrete loops.
Right now, smashing these forces together and finding a single, unified model that describes all of them is the holy grail of modern theoretical physics. Until we get that single model, the true nature of "before the beginning" will remain one of the universe's best-kept secrets.
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