Brian Greene

Brian Greene, professor of physics and mathematics, Columbia University.

Now, you can't take that too far.

None of us really imagined that if you asked the equations, what are we gonna have for dinner tomorrow night, the equations will spit out fried tofu and spring rolls or something like that.

But at the level of the fundamental ingredients, the particles that make up the universe,

their properties.

The hope and the goal is that the theories that we work out will apply everywhere and tell us about everything.

You just said everything.

Yes.

As in everything.

Right, so there actually are a number of ways that physics comes upon this idea of other universes.

Maybe the most intuitive

is to think about the Big Bang that sent space rushing outward and matter could cool and yield to stars and galaxies, that wonderful picture that we've had with us since the 1920s.

We have, in the interim decades, come to the possibility that the Big Bang may not be a one-time event.

That is, there may have been many Big Bangs, there may continue to be Big Bang-like events, each spawning its own universe.

If that were the case, then our universe would then be viewed as one of many in this grand collection emerging from all of these events.

Big Bang-like events.

vastly different.

That's right.

So when we study the equations for the production of these universes, we see in the mathematics that the other universes could have different features, different particle compositions, different masses of the particles, different forces.

Oh, I wouldn't describe it like that at all, as you might imagine.

Rather than...

view this as an incredible loss of understanding, the right way of viewing it, I think, is to recognize that certain questions that we were asking when we thought there was just one universe were the wrong questions.

Meaning what?

Well, he says here's the way to think about it.

This is how it always goes.

We've seen this before in the history of science.

Take Kepler.

And Kepler spent a long time trying to find an explanation for why the Earth is 93 million miles away from the sun.

93 million.

Kepler thought that has to be a really important number, a key to a deeper mystery.

But we now know that he was barking up the wrong tree.

Why?

There isn't just one planet.

There are many planets.

In fact, many planets around many stars.

And the distances of those planets from their host star varies over a wide range of possibilities.

That is progress.

That is understanding.

And then it frees you up to ask other kinds of questions, such as, what's the law of gravity?

What is the equation that allows us to understand how the sun forms?

So those are real questions.

And when you can toss out the ones that are red herrings that you thought were deep, but they're actually just asking the wrong question, that frees you up to make progress.

That would be pretty heavy and exciting to describe the underlying laws that govern all universes, regardless of their detailed features and what it would be like in that universe or that universe or that universe way over there.

We don't know very much observationally, sure.

We can't see them.

We don't know very much experimentally.

So they're definitely on a very different footing from that perspective.

emanating through the walls we might be able to listen in he says and take a couple of measurements which would be quite wonderful and in that case at least there's a chance that we'd get observational evidence of the existence of these other realms and at that point i would begin to say hmm maybe there's something really to this so the physics you're doing says i can't go there i can't observe it at least for the moment all i have is my brain and my math

The things that you were describing need not always be the case.

Really?

Yes.

What would be the case is that the fundamental governing equations, the mathematical laws, would be the underlying architecture that governs what happens in those places.

But environmental details can change things fairly dramatically.

Gravities and environmental details?

Yes.

That's actually something you know at some level right now, right?

On the moon, you could jump a lot higher than you can here.

So if you didn't realize... But I do think that two bodies do attract each other.

That's right.

So there is a fundamental law of gravity that manifests itself in different ways based on the environment.

All right, so let me say that again, or ask it again.

Are there fundamental laws that you think operate in all universes?

Yes, yes, absolutely.

And why do you think that?

That is the starting point.

When we come upon this possibility of other universes...

It's not a crazy idea that we dream up late at night when there's nothing else to think about.

These are ideas that emerge from the fundamental equations that we use to describe the things that we do see in the world around us and we follow the equations and the equations suggest to us there might be these other universes.

So we have equations, we analyze them, and we interpret what they're telling us about reality.

But those are the very equations that come to this possibility of other universes.

Then those are the equations that govern those other universes.

The starting point is let's assume that these are the fundamental... Doesn't it sound an awful lot like, why is God three in one?

I couldn't disagree with you more.

I thought not.

It has absolutely nothing to do with faith.

The reason why we trust the equations is because we've got centuries worth of observational and experimental evidence that the equations take us in the right direction.

Here.

Here.

and it's those very same equations that work here that we are following to their logical conclusion to see where the mathematics takes us right so if you remember the the train of reasoning here you might have just projected here into there that's faith talking though you can't go there all you can do is say well what works but my deep understanding of here

I don't know why it has to be, but that's what you just said.

No, it's actually the reasoning goes in somewhat reverse order from that.

We build mathematical equations to describe here.

We then follow those equations and say, oh my goodness, those equations that we developed to describe here are telling us that there is something over there.

And then we're like, wow, the equations do a great job of describing things here, and the equations have this feature that they tell us there's another place over there.

Maybe that's possible.

The key thing also- This is logic in your mind.

Oh, that's always the possibility.

In fact, it's likely the possibility.

In fact, 99.99% of everything we do is wrong, not from the point of view we make a mistake, but... But the wrongness is a deep wrongness.

In terms of whether the math is somehow contradictory and coherent in some way.

Yes, your tools of learning are not working.

Yes, that would suggest that we were both wrong and that there's a deeper overarching framework.

I mean, I...

I hate to use the word faith, but the one point where I'll give you faith is this.

I do have a deep faith that the universe is coherent.

And by universe, call it multiverse, whatever word you want to use, the whole thing.

I do believe that it's coherent.

Now, whether that means it follows mathematical laws, I don't know.

It could be the case that, you know, when we talk to those aliens that we encounter one day and they say, okay, show us what you got.

We bring out our equations and they kind of laugh at us and say, oh, you guys are still stuck on math.

You know, and they said, yeah, you know, a thousand, 10,000 years ago, we were doing math too, but here's the real way of describing it.

Now, what they'd be showing us with the real way of describing it, I have no idea.

I can't even imagine what it would be that would be non-mathematical.

So I do have a deep faith that it's coherent.

And the only tool that I know how to encapsulate that coherence are mathematical equations.

So if Zantar Brian and Brian here come up with equations that collide with one another and don't work, to me it just means that both were wrong and there's some bigger overarching coherence that we've yet to find.

That's it.