What Happened Before the Big Bang?

SPEAKER_1 (0:00)

This episode is brought to you by Accenture. When you're advertising operations fall out of sync, everything else follows. Spotify and Accenture are working together to reinvent the rhythm of ad sales. Using automation, analytics, and smarter workflows to simplify campaign delivery and access better data across the business. The result? Less time spent on operations, more time connecting brands with the moments and fandoms that matter most. Learn more at accenture.com/spotify.

SPEAKER_2 (0:31)

This episode is brought to you by Google Chrome. You think you know a browser, but Gemini and Chrome, that's new. It can help you with practically anything on the web, like restoring a vintage motorcycle from a 50-page restoration block, or finally break down that long article you've had open for weeks. Gemini and Chrome is here for it. Ready to make anything online make sense? There's no place like Chrome. Check responses set up required compatibility and availability varies 18 plus.

Matt O'Dowd (0:56)

We actually have a pretty good idea of what might have happened before the big bang. That is, as long as you define the big bang as the universe's early hot dense expanding state that's well described by Einstein's equations. That picture of the big bang is very solid, down to about a trillionth of a second after the supposed beginning of time. We can make good guesses down to about 10 to the power of negative 30th of a second. But did anything happen before that? Well, maybe everything.

The universe almost certainly did not explode from a singular point. We covered that misconception recently. These days the best accepted description of the time before the big bang is given by inflation theory. The idea is that the energy trapped in the so-called inflaton field caused exponential expansion of space. This was the bang in the big bang. In previous episodes we looked at why cosmologists think we need inflation and what could possibly cause it. That last one is definitely worth a watch if you haven't yet, because today we're going to peer further back in time and explore a stunning implication of inflationary theory. See if we accept that inflation happened at all, it's hard to escape the conclusion that it never actually stopped. And in fact, our universe is but one bubble among countless others in an eternally inflating greater universe.

Cosmic inflation, if it actually happened, was driven by the inflaton field, which had the bizarre property of containing a ton of energy, even in the absence of particles. It had a non-zero vacuum energy.

Now, in a recent episode, we talked about how such a field could drive exponential expansion. But we stopped short of discussing what the field actually is and what the real implications are of its existence.

Before we make any real predictions about the behavior of an inflating universe, we probably should know more about the field that drives it. To start with, you need a particular type of field to cause inflation. Something called a scalar field. This is actually the simplest type of quantum field because it's described by a single number, a scalar, everywhere in space. Other fields, like the particle field or the electromagnetic field, are described by multiple components and vectors instead of single numbers. We know that scalar fields exist, or at least one does. That's the Higgs field, which gives elementary particles their mass. The inflaton field would be another such scalar field. Or it might even be the Higgs field. Physicists are still arguing over that one.

I mentioned last time that quantum fields can hold energy without actually having particles. They do this through a process called self-interaction. You can think of a field...

SPEAKER_1 (3:56)

This episode is brought to you by Accenture. When your advertising operations fall out of sync, everything else follows. Spotify and Accenture are working together to reinvent the rhythm of ad sales, using automation, analytics, and smarter workflows to simplify campaign delivery and access better data across the business. The result? Less time spent on operations, more time connecting brands with the moments and fandoms that matter most. Learn more at accenture.com/spotify.

SPEAKER_2 (4:27)

This episode is brought to you by Google Chrome. You think you know a browser, but Gemini and Chrome, that's new. It can help you with practically anything on the web, like restoring a vintage motorcycle from a 50-page restoration block, or finally break down that long article you've had open for weeks. Gemini and Chrome is here for it. Ready to make anything online make sense? There's no place like Chrome. Check responses set up required compatibility and availability varies 18 plus.

Matt O'Dowd (4:52)

With a high field strength, as being full of virtual particles, these are ephemeral vibrations in the field that are constantly tugging at the field as the field tugs at them. This self-interaction gives the field some potential energy. It's potential energy because the field would much rather reconfigure itself into a lower energy state, in which case that stored energy would be converted into another form– for example, into real particles. Although scalar fields are the simplest, they can exhibit complicated relationships between this potential energy and the field strength. In our last inflation episode we looked at the case of old inflation proposed by Alan Guth in 1979