“The Big Bang and Beyond” Shows the Big Bang Started Everywhere

cosmic phenomenon marks earliest point of possible study—for now

By Jonny Lupsha, Wondrium Staff Writer

One of the most popular misconceptions about the Big Bang is that it was even an explosion at all. It actually occurred across the universe at the same moment. Looking back in time, the universe was increasingly dense, until a point about 13.5 billion years ago when it was at its highest density. The universe before that was so incredibly dense that all basic laws of physics as we know them can’t describe it.

So what’s the real story with the Big Bang? In his video series The Big Bang and Beyond: Exploring the Early Universe, Dr. Gary Felder, Professor of Physics at Smith College, gives a much clearer definition of the Big Bang, while straightening out some of its most misunderstood concepts.

The Universe Walks the “Planck”

“About 13.5 billion years ago, there were no galaxies,” Dr. Felder said. “All of space was filled with an extremely dense gas. At earlier times, that gas was even denser. Projecting backwards, we conclude that 13.8 billion years ago, the universe was at what’s called Planck density, a higher density than we have ever observed.”

Before that, there’s no way to tell. According to Dr. Felder, the basic laws of physics that we know are quantum mechanics and general relativity, but when someone tries to use them to describe the universe at or above Planck density, contradictory or meaningless results emerge. Why?

“Planck density is about 1093 grams per cubic centimeter, or roughly what you would get if you crammed a billion galaxies into a space the size of an atomic nucleus,” he said. “There is no chance of us producing this density in a lab in the foreseeable future. Until we know how matter behaves at or above Planck density, we can’t say what happened before that critical moment 13.5 billion years ago.”

Since we can’t describe exactly what happened before that, Dr. Felder said, there’s a big problem with calling the Big Bang “an explosion from a state of infinite density.” These questions, though, have driven him his entire career.

It’s Not How You Start…

Some models of the universe claim that the Big Bang was a moment when the universe was infinitely small, then followed a fraction of a second later by Planck density. However, Dr. Felder said, those timelines are based on equations that scientists know are false during that period. Therefore, it’s important to lay out what the Big Bang does and doesn’t tell us.

“The Big Bang is not a moment when the universe had zero size or infinite density,” he said. “Rather, the Big Bang is a moment of incredibly high but finite density that we call Planck density. The Big Bang did not happen at some special point in space; rather, the Big Bang happened everywhere in the known universe at once.

“Perhaps most importantly, the Big Bang is not necessarily the beginning of the universe.”

Instead, the Big Bang began at the earliest moment we can currently talk about. Dr. Felder stressed that the Big Bang model is not a theory of how the universe began, but a theory of how the universe has evolved in the last 13.5 billion years.

The Big Bang and Beyond: Exploring the Early Universe is now available to stream on Wondrium.

This article is part of our “Deeper Dive” series where we examine the stories behind our Wondrium Shorts on YouTube.

Edited by Angela Shoemaker, Wondrium Daily