Cosmic Queries– Multiverse Madness with Max Tegmark

Summary

StarTalk Radio: Cosmic Queries – Multiverse Madness with Max Tegmark

Release Date: March 14, 2025

Introduction

In this intriguing episode of StarTalk Radio, host Neil deGrasse Tyson teams up with his co-host Chuck Nice and illustrious guest Max Tegmark, a renowned physicist from MIT, to delve deep into the enigmatic concept of the multiverse. The conversation weaves through scientific theories, historical anecdotes, and engaging humor, offering listeners a comprehensive exploration of parallel universes and their implications.

Guest Spotlight: Max Tegmark

Neil warmly welcomes Max Tegmark, highlighting their longstanding association dating back to Tegmark’s tenure at the Institute for Advanced Study and Neil’s postdoctoral work at Princeton. Max humorously corrects Neil’s initial remark, emphasizing that the multiverse theory suggests he isn’t the "one and only" Max Tegmark (02:32).

Max is celebrated for his insightful books, including Our Mathematical Universe, which posits that everything is fundamentally mathematical, and Life 3.0, which explores the future of intelligent life. Neil commends these works as “a gift to civilization” (04:50).

Understanding the Multiverse: Levels and Definitions

Max introduces the concept of the multiverse by categorizing it into four distinct levels, likening them to Russian dolls nested within one another:

1. Level 1 Multiverse (02:11): Represents regions of space beyond our observable universe. Since the universe is vast and possibly infinite, there exist areas where light hasn't yet reached us, effectively making them separate "universes."

2. Level 2 Multiverse (12:56): Arises from the theory of cosmic inflation proposed by Alan Guth and Andre Linde. In this model, different regions undergo varying inflationary processes, leading to diverse physical constants and particle types across these vast spaces.

3. Level 3 Multiverse (12:56): Rooted in quantum mechanics, this level suggests that every quantum decision spawns parallel realities. When a decision occurs, the universe splits, creating branches where each possible outcome is realized.

4. Level 4 Multiverse (12:56): The most speculative level, where all mathematical structures exist as separate universes. This encompasses every possible mathematical reality, making it the most expansive form of the multiverse.

Max explains that these layers build upon each other, creating increasingly complex and interconnected universes (14:37).

Historical Context and Scientific Evolution

Max recounts the historical resistance to multiverse ideas, referencing Giordano Bruno’s persecution for proposing an infinite universe (07:05). He contrasts past challenges with the current scientific community's gradual acceptance, highlighting that contemporary physicists no longer dismiss the multiverse as "too fringe" but rather engage with it as a legitimate area of study.

Scientific Evidence and Testability

Addressing skepticism, Max draws parallels to Einstein's theory of general relativity, which makes untestable predictions yet remains a cornerstone of physics due to its empirical successes. He emphasizes that while we cannot directly observe other universes, the multiverse theory makes testable predictions, such as the ongoing expansion of space confirming the Level 1 multiverse (32:00).

Max argues that exploring the multiverse can lead to unforeseen scientific advancements. He cites the development of quantum mechanics as an outcome of probing seemingly untestable theories, which ultimately revolutionized technology and our understanding of the universe (36:07).

Audience Questions and Insights

1. Infinite Infinities Explained (18:04)
   Question by Eric Gross: "Can you explain the mind-boggling idea of infinite infinities?"
   Max elucidates the concept by comparing countable and uncountable infinities, referencing Georg Cantor’s work on the hierarchy of infinities. He explains that infinities can vary in size, with some being larger than others, creating a "tower of infinities" (19:30).

2. Combining Parallel Universes and Multiverses (26:33)
   Question by Chris Hampton: "Could the parallel universe theory and the multiverse theory be combined?"
   Max clarifies the scientific distinction between metaphorical uses of "universe" and the rigorous definitions in physics. He emphasizes that while poetic interpretations liken organisms to universes, scientifically, a universe encompasses all that can be observed or interacted with (27:05).

3. Impact of the Multiverse on Our Universe (17:38)
   Question by Curtis Zeidelhack: "Conceptually, I do not really understand how a multiverse affects our universe. What is the most important effect on our universe?"
   Max explains that the multiverse theory doesn't directly alter our universe but provides a framework to understand phenomena like dark energy's fine-tuning. He suggests that an expansive multiverse allows for numerous variations, making the existence of our particular universe's conditions statistically probable (37:52).

4. Origin of the Multiverse and the Big Bang (41:37)
   Question by Woody: "What are your thoughts on how a multiverse could actually begin with? Would each one require a Big Bang?"
   Max discusses how inflation theory posits that a single Big Bang can give rise to multiple universes through continuous expansion, ensuring that even highly improbable events, like the existence of Chuck, occur somewhere in the vast multiverse (42:45).

5. Between Universes and Quantum Multiverses (42:00)
   Question by Cameron Bishop: "Is it flawed to ask what's between these universes? Is that measurable?"
   Max describes the space between Level 1 and Level 2 multiverses as perpetually expanding due to inflation, making these regions inaccessible. In contrast, the quantum multiverse operates within Hilbert space, existing in a different dimensional framework (43:16).

6. Decision-Making and Multiverse Creation (46:04)
   Question by Jay Hunt: "Is a new multiverse created every time we make a decision?"
   Max affirms that in the Level 3 multiverse, every decision leads to a branching of realities, resulting in parallel outcomes where different decisions have been made. This means that each possible outcome of a decision exists in a separate, equally real universe (46:27).

Key Takeaways and Conclusions

• Multiverse Levels: Understanding the distinct layers of the multiverse helps clarify how parallel realities might coexist based on spatial, inflationary, quantum, and mathematical principles.

• Scientific Validity: Despite being challenging to test directly, multiverse theories are grounded in established scientific frameworks like inflation and quantum mechanics, making them plausible extensions of current knowledge.

• Philosophical Implications: The multiverse concept diminishes anthropocentric views, placing human existence within a broader, potentially infinite cosmic landscape. It also provides explanations for fine-tuning and other cosmic mysteries without resorting to supernatural explanations.

• Future Research: Exploring the multiverse opens avenues for new scientific discoveries, potentially leading to breakthroughs analogous to those seen with quantum mechanics.

Notable Quotes

• Max Tegmark on Infinities:
  “Some infinities, which intuitively would seem like they're much bigger, are actually all the same size." (19:30)

• Chuck Nice on Quantum Multiverses:
  “That is awesome.” (47:01)

• Max Tegmark on Dark Energy and Multiverse:
  “The picture you get then is that the bigger space is like the Sahara desert. It's mostly just a barren wasteland with no galaxies. But in a few places now, that knob is set just right and you have an oasis where there is life and there are galaxies and there is StarTalk.” (39:55)

• Chuck Nice on Level 3 Multiverse:
  “That is crazy.” (47:39)

Conclusion

This episode of StarTalk Radio masterfully blends complex scientific theories with relatable analogies and humor, making the profound concept of the multiverse accessible to listeners. Max Tegmark’s expertise provides depth to the discussion, while Neil and Chuck’s dynamic hosting ensures an engaging and thought-provoking experience. Whether you’re a science enthusiast or a casual listener, this episode offers valuable insights into one of the most fascinating topics in modern physics.

Transcript

[Unknown Announcer]

Hanaday presents, in the red corner, the undisputed, undefeated Weed Whacker guy. Champion of hurling grass and pollen everywhere. And in the blue corner, the challenger, extra strength hataday eye drops that work all day to prevent the release of histamines that cause itchy allergy eyes. And the winner by knockout is Patternay. Patternay. Bring it on.

[Neil DeGrasse Tyson]

Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. I'm your host, Neil Degrasse Tyson, your personal astrophysicist. And this is going to be a Cosmic Queries edition. The ever popular format that we started many years ago and it just keeps going strong. And today's topic is gonna be the Multiverse. I got with me my co host, Chuck.

[Chuck Nice]

Hey, Neil. How are you, Chuck?

[Neil DeGrasse Tyson]

Nice. You know, you get in such a schooling here with all this cosmic knowledge and we're have to give you a degree of your own.

[Chuck Nice]

No, no, no. Because then that, you know, normally once you get the degree, that means that your time at the institution is over unless you start pay.

[Neil DeGrasse Tyson]

Okay, so they kick you out the front door.

[Chuck Nice]

Right. So I'm just gonna continue to. I'm just staying in school forever.

[Neil DeGrasse Tyson]

That's lifelong learner.

[Chuck Nice]

All right, that's it. Just stay in school.

[Neil DeGrasse Tyson]

Well, this topic is in part celebration for the release of the second Start Talk book. And guess what that book is called, Chuck.

[Chuck Nice]

Let me take a stab at it. Could it possibly be Cosmic Queries?

[Neil DeGrasse Tyson]

Cosmic Queries inspired by this very format.

[Chuck Nice]

Yes.

[Neil DeGrasse Tyson]

There are questions that people just ask that are so deep and so interesting and not all of them can we get to on a podcast. And so we had to like take it to the book. And so there's a whole section in that book on the Multiverse.

[Chuck Nice]

Nice.

[Neil DeGrasse Tyson]

Yeah, yeah. And I learned almost everything I know about the Multiverse from our guest today. And that is the one and the only Max Tegmark. Max, welcome back. I mean, I've had you in other events at the museum for Hayden Planetarium panels and things. It's just always good to know you're in arm's reach of us.

[Max Tegmark]

Thank you. But you know, you just said something dubious. You said the one and only Max Tegmark. And if you take the Multiverse seriously. I'm not the one and only.

[Neil DeGrasse Tyson]

Damn, I just got schooled on my first sentence. But Max, we go way back. I mean, when you were at the Institute for Advanced Study and I was postdoc ing at Princeton, I think that's When I first met you and I followed your career, it's been a brilliant melange of topics that are just so interesting. And the multiverse is the least among them that I have found interesting in your career. So we'll have to have you back for other topics for sure. Plus Chuck.

[Chuck Nice]

Wow, that is a serious compliment. You know what I mean?

[Neil DeGrasse Tyson]

If the universe is a side, it's a side gig.

[Chuck Nice]

Multiple universes are the least interesting thing. Like.

[Neil DeGrasse Tyson]

I'm sorry, I'm just leveling with you here.

[Max Tegmark]

To be honest, guys, it has been especially my side gig all along. Just so I wouldn't tank my career with it. Because, like, when I was a grad student, I was already fascinated by this, but nobody else seemed to be, and it was generally considered a bit too fringe. So I played the multiverse very close to my chest and I didn't even. I even wrote some papers when I was a grad student. I didn't show my advisor until after he had signed my PhD thesis under a pseudonym.

[Neil DeGrasse Tyson]

John Doe. Yes. Okay.

[Chuck Nice]

Oh, that's so funny.

[Max Tegmark]

And it's so weird how now gradually some of these topics have actually come in a bit from the cold and gone from being just considered career ending to being things that considered legitimate scientific controversies that we actually talk about openly at physics conferences.

[Neil DeGrasse Tyson]

So you're a professor of physics at mit, of course. The Massachusetts Institute of Technology, basically up the street in Cambridge, Massachusetts. And Chuck, I've always been jealous of this man's name. It's like movie star Max Tegmark starring.

[Chuck Nice]

It does. It could be either the star of the show or the producer. This is a Max Tedmark production. Yeah, it works either way.

[Neil DeGrasse Tyson]

All of the above. Right. And Max, you've got a couple of books under your belt, at least one of my favorites is Our Mathematical Universe, where you argue that everything is math. And if everything's math, someone could have programmed it that way. And so a brilliant exercise there. And of course, Life 3.0, where you're exploring the future of what we even think of as life. And I've enjoyed both of those books, so thanks for. I think of them as a gift to civilization to share in how you think about this world.

[Chuck Nice]

And I enjoyed the conversation that I heard on NPR about your book about mathematical universe.

[Neil DeGrasse Tyson]

Okay, but now we have the guy. We got him ourselves.

[Chuck Nice]

Exactly.

[Max Tegmark]

You know, actually, I changed the name of that book in the last second for reasons we're gonna talk about now. The first title was the Mathematical Universe. And then I thought, that's so arrogant. If we really believe that there are other universes. We shouldn't just say the universe ours. We should talk about, Be more humble and acknowledge that it might just. That our universe might not be the only one.

[Neil DeGrasse Tyson]

Okay. All right. So we went through a brief last minute title change so that you wouldn't sound like an a hole.

[Max Tegmark]

We used to talk about the solar system, and then we realized, oops, there are others, right?

[Neil DeGrasse Tyson]

Yeah, or the universe. And we're not saying that anymore. It's our universe. I like that. It's a good shift for that.

[Chuck Nice]

You changed the universe into the humble verse. That's cool.

[Neil DeGrasse Tyson]

Ooh, humble verse. Very good, Chuck. Making up words on the spot. So, Max, tell me what motivated people to you and your. You know, either you, early on, when you were doing this sort of under the COVID of night to what is now mainstream research on the multiverse, what motivated it?

[Max Tegmark]

Well, I think first of all, throughout human history, you know, we've had this epiphany again and again that, hey, stuff is bigger than we thought. And we, you know, we used to go into it with this hubristic assumption that all we knew about, with all was all there was. Kind of like an ostrich would have had to this sound. And then people realized, oh, by the.

[Neil DeGrasse Tyson]

Way, the corollary to it's bigger than we thought is we're littler than we thought. The flip side of that coin, we.

[Max Tegmark]

Realized, actually we're part of this huge. We're standing on this huge round ball in space, which in turn is just part of this gigantic solar system. Part of a galaxy, part of a cluster of galaxies, part of a super cluster, part of this that we then would call our universe, and why stop there? So people started wondering, could there be. And the earliest people got into much more trouble than I ever did in grad school. Like Giordano Bruno 400 years ago, started talking about how maybe space went on forever. And you know what happened to him, right?

[Neil DeGrasse Tyson]

Yeah, he was burned at the stake, upside down with something plugged into his mouth so that even in death he could not repeat these heresies. They drove a steak into his mouth so that even when he died, you.

[Chuck Nice]

Know, you know, that's what I liked about that time, the overkill. Overkill. Everything was overkill.

[Max Tegmark]

Now. I went to Campo de Fiore, actually, in Rome, where this happened, and I started to think, you know, compared to that, that just getting burned on the job market is a lot less of a threat. So we're making some progress, and it's.

[Neil DeGrasse Tyson]

A little bit of progress. But just to be clear, that square that in Italy, there is, in all fairness, there is a statue to him where he's looking very solemn, but it's a very honorific statue in his memory.

[Max Tegmark]

It is, yeah.

[Chuck Nice]

Small consolation for being burned at this gate.

[Neil DeGrasse Tyson]

I'll take life, you keep your statue. Is that what you're telling me?

[Chuck Nice]

Thank you. Exactly.

[Max Tegmark]

But you asked this very good question, what drove us to these things? And it's basically just natural logical steps. Euclid himself postulated that space is infinite. And when we were kids and we started wondering, does the space go on forever? It seemed pretty natural that there wouldn't just be an end to it. So if you just take that idea logically, then that means that the part we can see this is finite because light has only reached us from this spherical region that it could get here from during the 13.8 billion years since our Big Bang. So if that's what we call our universe, then by definition, there are others, other regions of space just as big, just as cool. And it's sort of hard to dismiss right now. I don't have a single astrophysics colleague anymore who thinks space magically ends right at that edge. And in fact, you can just wait one day and you see some more light arriving from farther away. Right. And then. And then. So that's what I call the Level 1 multiverse. Just other regions of space that we haven't had any access to. But then it gets. It gets kind of weirder.

[Neil DeGrasse Tyson]

So initially, it wasn't that people were motivated to try to answer some other question. They just more fully explored what we were already thinking and already knew to be true about the universe. So in that sense, it's not some epiphany, it's just an extension of what we're already thinking. Is that a fair way to think about your level one multiverse?

[Max Tegmark]

I think so. And I think a lot of the pushback honestly, wasn't really based on science so much, but based on arrogant hubris. You know, the reason Pope Urban VIII or whatever was so pissed at Galileo, you know, wasn't because he had a good scientific argument that he. We were so stuck to the idea that we. Everything orbits around us. You know, we humans are so important, and we didn't like to be demoted to just being an average planet and an average solar system orbiting a galaxy, et cetera, et cetera. And I think we see still a little bit of that today. Some people argue that they don't like this idea of reality being even bigger. Just because it makes their egos feel even smaller.

[Chuck Nice]

After the last four years, I can't imagine that people would actually have hold to those sentiments.

[Neil DeGrasse Tyson]

All right, so what I don't know, because I haven't quizzed people, is what are they thinking of when they hear multiverse? And my sense is they're thinking maybe a parallel universe that you might be able to sort of move between at some distant future time. So is there any truth to the concept of a parallel universe in the way it's commonly thought of in the public?

[Chuck Nice]

Is there an evil Chuck somewhere? Exactly.

[Neil DeGrasse Tyson]

With a goatee. Oh, you already have a goatee.

[Chuck Nice]

Is there a clean shaven evil Chuck?

[Neil DeGrasse Tyson]

You are the evil Chuck, Chuck.

[Chuck Nice]

Oh, my God. Oh, my God. That's right.

[Neil DeGrasse Tyson]

Just think that through.

[Max Tegmark]

What's incredibly confusing here is that different people mean different things when they say universe, and they mean talk about different kinds of. And in fact, I remember once very vividly, Martin Rees had organized a conference in his house about these forbidden topics. And I just heard you, Chuck, these.

[Neil DeGrasse Tyson]

Are the kind of friends we have that you get that you get invited for tea and you solve the issues of the universe. Okay, go ahead.

[Max Tegmark]

This was considered pretty taboo back then, but because Martin was organizing it, people still came and behaved. But I noticed that two people were arguing about the multiverse. And I realized they're talking past each other. One guy was talking about what we call the inflationary multiverse, which is just really big space. And we can get back to that. Another guy was talking about the quantum multiverse, and they thought they were talking about the same thing. So I felt I have. I stood up and said, hey, wait a minute. Aren't there actually three different, no, four different kinds of multiverse that we should give different names to to not confuse ourselves so much? And then I wrote that up in the book you mentioned.

[Neil DeGrasse Tyson]

But just to be clear, the book that you're talking about is you posted something, it's online, which is a very clean and clear exposition of the multiple levels of the multiverse. And that's what we referenced when we included, when we fleshed out our section on the multiverse in Cosmic Queries. So I just want to be clear that, you know, you're not just pulling this out of your ass. You've thought about this for a long.

[Max Tegmark]

Time, so I think it's very important. But just be clear on what we're talking about. Yeah. Thank you. So by our universe, we mean what astronomers call our observable universe. It's just a spherical region of space from which light has reached us so far. I know this. Then what I call the Level 1 multiverse is just other parts of space that are so far away that light hasn't reached just yet. Level 2 multiverse is what you get if you take seriously Alan Guth and Andre Linde and others, and the theory of inflation that made our space so big, which says that far, far away in the same space now you have something much more diverse than you might have thought, where even the number of different kind of quarks could be different or the sort of forces that are there are different, and we can talk about why. And then there's this third kind, and that's what gets more into the parallel evil feeling thing, which has to do with studying not the big, but the very small, studying quantum mechanics, where you can argue, and people love arguing about that at physics conferences, that in some sense our reality feels like it's splitting out into parallel branches. And that's the whole. If that is true, you can tap into that weirdness by building quantum computers. And then finally there's the fourth one, which is so weird that almost nobody except myself believe in it, which is the biggest. And I think of all of this as basically Russian dolls. They're nested, they're all inside of each other. You start with our universe. Many of those, that's level one, many of those, that makes level two, many of those makes level three, and many of those makes the ultimate one, the fourth level.

[Neil DeGrasse Tyson]

So these are multiverses of multiverses.

[Max Tegmark]

That's right. That's right.

[Chuck Nice]

But the only one that ever gets any real attention is that kind of tree limb version that you depicted, this splintering, where there's so many different infinite paths that are separate yet existing simultaneously. That seems to be the one that captures the imagination of every sci fi writer. And even Rick and Morty, which is like a hugely popular show. I mean, it's like, it's, you know, because I think you could do so much with it. You know, there's an infinite number of Ricks, and they're all geniuses. So they, you know, so how. I mean, you have an unlimited reservoir of stories to tell.

[Neil DeGrasse Tyson]

Chuck. Chuck Max is Rick.

[Unknown Announcer]

Hataday presents in the red corner, the undisputed, undefeated weed whacker guy, champion of hurling grass and pollen everywhere. And in the blue corner, the challenger, Extra strength adity eye drops that work all day to prevent the release of histamines that cause itchy allergy eyes. And the winner by knockout is Patternay. Patternay. Bring it on.

[Neil DeGrasse Tyson]

Hi, I'm Ernie Carducci from Columbus, Ohio. I'm here with my son Ernie because we listen to StarTalk every night and support StarTalk on Patreon. This is StarTalk with Neil DeGrasse Tyson. Chuck, you've got questions for us? Let's do it.

[Chuck Nice]

Okay, let's just jump right into all the questions that we have taken from our Patreon patrons. People who support us out of their substance to keep our show going. So thank you guys for your support. And if you are listening to this and you want to be a Patreon member, go to patreon.com start talk and, and give us some support and maybe I'll read your.

[Neil DeGrasse Tyson]

I didn't know how you're going to end that.

[Chuck Nice]

Yeah, yeah.

[Neil DeGrasse Tyson]

Maybe I'll think about.

[Chuck Nice]

Maybe, maybe I'll think about reading your. No, of course I'm joking. Of course I'll read your letter and I'll butcher your name. No doubt, no doubt. Here we go. All right. This is Eric Gross. He says, hello, fellow Earthicans. Can you explain the mind boggling idea of infinite infinities?

[Neil DeGrasse Tyson]

Oh, wow.

[Max Tegmark]

Wow, that's a good one.

[Chuck Nice]

Wow, that's a great question.

[Neil DeGrasse Tyson]

How about this? Wait. So Max, let's start simple and let me ask you, what does it mean for one infinity to be bigger than another? And then let's take it from that into that, directly into the question. Let's drive the truck right into that question.

[Chuck Nice]

Another infinity, big. Wait a minute, guys, Give me one second here.

[Neil DeGrasse Tyson]

Wait, wait, wait. What? Chuck?

[Chuck Nice]

All right, sorry, I gotta get this little pipe here before we, you know, if we gonna talk about one infinity being bigger than another, I'm just saying I need to be prepared.

[Neil DeGrasse Tyson]

The pipe has to be right there. Okay?

[Max Tegmark]

If you have a pile of oranges and you have a pile of apples, and you want to know is it the same number of apples as oranges? The way you do it is if you can pair up each apple with exactly one orange, you say the two numbers are the same. So now play that game with infinities and weird stuff happens. Let me, for example. You might think that there are more numbers 1, 2, 3, 4, 5 than there are even numbers 2, 4, 6. But they're actually the same because you can pair them up. I can pair up one with two. I can pair up eight with 16. I pair up every number with one that's twice as big, which is always even. So it's very counterintuitive. So for a while, mathematicians start to think.

[Neil DeGrasse Tyson]

But just to Be clear. You said something, but not everyone knows this, Max, that twice any number, any whole number is always an even number.

[Max Tegmark]

Thanks for clarifying. Yeah, yeah, yeah.

[Neil DeGrasse Tyson]

That is always the case. So you can't take twice anything and end up twice a whole number and get an odd number. So when you say twice the number, that's always even. That's a fundamental fact about mathematics.

[Max Tegmark]

Okay, that's right. Pick me up. The quite weird conclusion is that some infinities, which intuitively would seem like they're much bigger, are actually all the same size. And some mathematicians start to think maybe all infinities are the in size. But then George Cantor came along and said, no, there are some infinities that are even bigger. And he proved famously that the number of real numbers like 3.1415 with infinitely many decimals, that there are actually more of those than the numbers you can count. And after that, people have realized that there's this whole tower of infinities. So what's that got to do with parallel universes and this question? Well, it's got a lot to do actually with the level one and the level two multiverse because.

[Neil DeGrasse Tyson]

Wait, wait, wait. Chuck has to take a toke. Okay, go ahead. Toque break.

[Chuck Nice]

Yes, exactly. So far. This is great. This is great.

[Max Tegmark]

I mean, take a deep breath because I'm going to tell you one of the things that I find the weirdest. This is one of the weirdest things I believe to be true.

[Neil DeGrasse Tyson]

And if Max finds it weird, brace yourself. Go.

[Chuck Nice]

Right. Exactly.

[Max Tegmark]

But it is actually impossible. It is, according to Einstein's theory of general relativity, possible to take a little piece of space, just finite and inside of there, make an infinite space that doesn't stick out anywhere and actually infinitely many, and make many different infinite spaces inside of this finite thing. So Alan Guth, Andre Linde, and others came up with this most popular theory we have so far for what put the bang into our Big Bang and made this expanding universe of ours, starting with something tinier than an atom. It's very, very big. And the ultimate party trick is inside of this tiny region. They can not only make one space, which, when you live in it, feels infinite. That's the level one multiverse for you in there. So it has room for infinitely many of our universes, but you can have infinitely many of those within there.

[Neil DeGrasse Tyson]

So you can have an infinite number of infinitely large universes in a finite universe, Basically.

[Max Tegmark]

That's why it feels so utterly weird. And the way that general relativity kind of pulls this trick is because Even though it was a finite volume of space, it has an infinite amount of future time to play with and it keeps stretching the space. And then general relativity has this funny thing where it can kind of mix up space and time. So that for someone who lives inside this, what they consider to be space, was something that you might have considered a little bit of time. And I don't want to get too nerdy about this, but you know, Einstein told us that what really we should only.

[Neil DeGrasse Tyson]

Now are you saying you don't want to get too nerdy? It's only just occur to you now?

[Max Tegmark]

I think they already blew it. But you know, Einstein told us, right, that we shouldn't think of reality as a three dimensional place where stuff happens, but rather as time being just the fourth dimension in this never changing place called space time. So if life is a movie, then space time is the whole dvd. And basically because you have this infinite future time to mess with, if you can sort of bend your definition of what space is in there, this is how Alan Guth and Andre Linde and Alex Vilenkin and others have, have demonstrated this apparently crazy thing that maybe everything we see here, an infinity of infinities, could actually be emerging inside of this little bubble.

[Neil DeGrasse Tyson]

So just to clarify your DVD analogy, what you're saying is we live as prisoners of the present, transitioning from our past to our future, so we experience a moment in time and many places in space. But if you have the whole DVD of the movie, then your entire timeline is manifest in that place, in that all at once, all at once, all the time of your life is in that dvd and you can have random access to it if you can move throughout the time coordinate. Is that a fair right reference to how you use the concept of dvd?

[Max Tegmark]

It is, it is. And that's right. Einstein even told some of his friends that they shouldn't worry so much about his death, because he argued that it's just from the space time perspective, an illusion. It's not like.

[Chuck Nice]

Right, because I'm already dead, man, and so are you. We're all dead, man. And we're not. I haven't even been born yet, man, and I'm dead. What?

[Max Tegmark]

It is pretty weird, Chuck. I mean, I'm sure sometimes people come up to you when they're lost and ask, hey, excuse me, but where am I right? But they never come and ask, when am I right? Local English we treat time as a very different sort of thing, as space. Whereas when we say what's the time? That's actually very Arrogant. Just like talking about the universe or the solar system, what is the time? I mean, that's saying that somehow the instant when we're having this experience is the only time. I mean, all the other times past and present in space time have just as much claim to be real. They certainly felt real to people who had experiences then. Right. So if we want to be a little bit more rigorous, we should always go ask people, Excuse me, when am I right now at this particular time having this experience.

[Neil DeGrasse Tyson]

Wow. Okay. So that doesn't have the arrogance that it otherwise would by asking, what is the time?

[Max Tegmark]

I mean, it's like going up and saying, what is the place?

[Chuck Nice]

Right.

[Max Tegmark]

Of course, where I am is the only place.

[Neil DeGrasse Tyson]

All right, Chuck, give me some more questions.

[Chuck Nice]

All right. Wow, that was way to kick things off. That is something else. All right, let's move on to, you know, that other level you talk about. This is Chris Hampton. Could the parallel universe theory and the multiverse theory be combined? For example, we are living in a universe with billions of other organisms. But what if each organism in the universe is itself a universe on a relative scale, each one thus containing billions of organism, so on and so on. So he's taking your nesting doll and breaking it all the way down to every single organism.

[Neil DeGrasse Tyson]

Right. But yeah, he's thinking, I mean, so, Max, if we have, as a lead into that the early concept of the atom, where people said, oh my gosh, atoms have structure and there's a nucleus and there's electrons orbiting. So that's just like the solar system. So maybe it's like turtles all the way down. So how do we go from any understanding of scales of everything's just on a different scale rather than something that's a completely different universe unto itself?

[Max Tegmark]

Yeah, very good question. We see, of course, in nature this feeling, beautiful hierarchy, right? You have some quarks stuck together into neutrons and protons that are stuck together into this big thing we call a nucleus stuck together in an atom. And then you can make molecules and cells and you can make Neil Degrasse Tyson and this society and a planet and galaxy, etc. What's different about the hierarchy of universes is it's not just that the hierarchy exists, but by definition. I like to define the universe, our universe, as everything that we could possibly have any access to with unlimited funding and never mind other stuff that's in the way. So. So if you're one person in a society, there are a lot of people you haven't met, but you could, in principle, Meet them so they're not part of another universe. You could, in principle go to Uruguay, even if you've never been there. Right. But you can never go 100 billion light years in that direction, even if you wanted to. It's just off limits to you. That's basically the definition I think is helpful about universe.

[Neil DeGrasse Tyson]

Okay. But otherwise we'd use the term sort of poetically or metaphorically. Like the cell is a universe unto itself.

[Max Tegmark]

Yeah.

[Neil DeGrasse Tyson]

You know, so I think that's fair. Poetically. But you're saying from the world of physics. No, that's not how we use the term.

[Max Tegmark]

Yeah, exactly. And I mean, it's whatever we need to have. We should have a word for everything we can access. It's very important for us, especially in the future, both if we're curious, that's the limits of what we can observe. And if we're ambitious, that's also setting roughly the limits of where we could ever go in the future. So if you don't want to call it universe, call it shmooniverse and make up another word for it. But it deserves to be called something. Right. And where. Space, I think, is a word that's better used to actually describe all of space. And it's not the same thing. Space is probably bigger than our universe.

[Neil DeGrasse Tyson]

We have confirmed that Chuck lives in the Schmooniverse. Just to be clear.

[Max Tegmark]

Yes.

[Chuck Nice]

The Schmooniverse is where all dismissive people live. Universe.

[Neil DeGrasse Tyson]

Schmooniverse.

[Chuck Nice]

Yeah, whatever.

[Max Tegmark]

The Tuniverse. So it's.

[Chuck Nice]

I don't mind the Tuniverse. Now you're making me hungry. Well, Chris Hampton, actually, it looks like he. From what you just said, is. Speaking of smoking, is that whole, hey, man, there's a universe in my thumbnail. Like that whole vibe. That seems to be where he's coming.

[Max Tegmark]

From, but it is. I like what you said, Neil. The reason people use it poetically in that sense is because we refer to things poetically as a universe unto its own. Basically, if it really is doing its own thing and not interacting with the rest. Right. Which is what we're trying to capture scientifically here.

[Chuck Nice]

Okay, so now I want to ask my own question, but I don't want to take up these people's time.

[Neil DeGrasse Tyson]

Chuck, are you a Patreon member? If not, shut the hell up and read the next question. Okay.

[Chuck Nice]

Well, Neil, I gotta tell you, you have bested me, sir. Cause that was a damn good point. Oh, my God. Hold on now. I gotta go online right now. I gotta get on Patreon. Right now so I can ask my question. All right, here we go. This is Curtis. Oh, man, you really got me with that one. Okay, this is Curtis Lee Zeidelhack, I think Seidel Hack.

[Neil DeGrasse Tyson]

Yeah.

[Chuck Nice]

He says, first and foremost, my name is pronounced Zadohawk. Okay, So I. Okay, I was wrong, but I got it close.

[Neil DeGrasse Tyson]

Okay.

[Chuck Nice]

Conceptually, I do not really understand how a multiverse affects our universe. What is the most important effect on our universe?

[Unknown Announcer]

Hataday presents, in the red corner, the undisputed undefeated weed Whacker Guy, champion of hurling grass and pollen everywhere. And in the blue corner, the challenger, Extra strength Hataday eye drops and work all day to prevent the release of histamines that cause itchy extra allergy eyes. And the winner by knockout is Patterny. Bring it on.

[Max Tegmark]

I love the question you just asked before we got cut off there about what's the evidence for this? Is this just silly?

[Neil DeGrasse Tyson]

Yeah, Chuck, who asked that again?

[Chuck Nice]

That would be Curtis Zeidelhock.

[Neil DeGrasse Tyson]

Yeah, he's wondering, do we feel see this other universe? And so another. The official way to say that is do we have experimental evidence that they exist? Right. Or this is what you talk about at the beer halls.

[Max Tegmark]

It's a really great question because by definition of what you mean by universe, you are not affected by things outside of it. So isn't that by definition untestable? And the interesting thing is, no, that's not true. First of all, if you just take the theory that space is actually much bigger than we thought and with more stuff in it. If that's false, that would mean that actually things kind of end at exactly the edge that we can see. Now, that's very testable. You just wait a little bit, and then light from farther away reaches you and keeps coming into view. We've already falsified that many times over. Now, there's a more profound way in which you can test this. Also, though, we have to remember in science, we test theories. And for a theory to be testable, you don't have to be able to test everything that it predicts, just at least one thing. Take Einstein's theory of general relativity. It predicts all sorts of stuff that we can observe, like how Mercury orbits around the sun in a different way than people thought it was supposed to because of Newton. We can test that. We can test how light is bent by gravity, et cetera, but it also predicts what happens inside of black holes, which you know very well. We cannot go and observe everything, come back and tell our friends about it. Why do we still take it seriously what happens inside black holes, because this theory of general relativity has passed so many of the tests that we could test, that we also start taking seriously. It's untestable predictions. And you can't just say, well, I kind of like what Einstein's theory predicts for the motion of Mercury and gravitational lensing and yada, yada, yada. But I don't like the interior black holes. I'm just going to opt out of that. Like, if I go to Starbucks and say, I want my coffee, but I'm going to opt out of the caffeine and have decaf. That's not the way science works. If you want to opt out of the black holes, then go come up with your own gravitational theory, which doesn't have black holes in it, but still succeeds in everything Einstein's theory did. That turns out to be such a tall order that despite a lot of smart people trying for 100 years, they've all failed. So what's that got to do with the multiverse? Well, replace general relativity now with the theory of inflation that we talked about. It makes a bunch of testable predictions. It predicts that our universe should be expanding, that it should be very uniform.

[Neil DeGrasse Tyson]

But wait, just to be clear, you're not actually replacing general relativity, you're enclosing it?

[Max Tegmark]

Yeah.

[Neil DeGrasse Tyson]

In inflation, isn't that correct?

[Max Tegmark]

Correct. Thank you for correcting me. We take generativity, and then we add some additional assumptions to it that there is a certain kind of substance there which behaves in a certain way. And then we do the math, and it predicts all sorts of things that we've tested now successfully, with great prediction, like these ripples in the microwave background, their statistical patterns, for example. I've worked, as, you know, a lot on trying to rule out this theory of inflation, and I've failed. And because of that, we take it seriously. And we also have to then take seriously the things inflation predicts that we cannot test, such as that space is actually way bigger than our universe.

[Chuck Nice]

Wow.

[Neil DeGrasse Tyson]

Okay. I think that's an excellent way to think about it. So if the one theory has these multiple consequences, it's okay if some of them you can't or you never will if the ones that you can test turn out to be correct.

[Chuck Nice]

Right.

[Neil DeGrasse Tyson]

And you say, if this is correct, I'm gonna take a stronger look over. I'm gonna start thinking about this. By the way, is it fair to say, Max, that if you explore the things you cannot measure, you might come up with a discovery that you can measure.

[Max Tegmark]

Very true, too, because very often when people have been going off and thinking about these things which they knew they could never test, it led them to ask questions. What led them back.

[Neil DeGrasse Tyson]

Back to a whole fresh way could test. Excellent.

[Max Tegmark]

For example, another very good reason. Not just we shouldn't think of these cool things just because they're fun, but. But they often turn out to be very useful. People started thinking about what the ultimate building blocks of matter were, and atoms and so on. And people for a long time thought that was completely useless. But then by thinking about that, they invented quantum mechanics, which gave us the whole computer technology, which lets us have this podcast now and so on.

[Chuck Nice]

Wow.

[Max Tegmark]

And that's another example, actually, of exactly this same question. The quantum parallel universes. Of course, we can't visit them either, but quantum mechanics predicts so much else that we can test, and it turned out to be very, very difficult to come up with a theory of physics that predicts only some sort of creation mechanism for our universe that creates only the part we can see and then stops and doesn't make anything more.

[Chuck Nice]

So let me ask you this with respect to what you're saying, Chuck, you're.

[Neil DeGrasse Tyson]

Not a Patreon member yet.

[Max Tegmark]

Maybe shine up during the break. That's right.

[Chuck Nice]

You never know what I did during the break.

[Neil DeGrasse Tyson]

I don't know what you did during the break.

[Chuck Nice]

That's right.

[Neil DeGrasse Tyson]

I'll let you slip one in. Go.

[Chuck Nice]

All right, so, Max, with respect to what you just said, are there things that we are able to observe, or at least able to observe the forces thereof that remain a mystery that may in some way be attached to the multiverse theory?

[Max Tegmark]

I would say.

[Neil DeGrasse Tyson]

Isn't that what we just answered? Is that. Are you saying, Chuck, if the multiverse is what it is, is there some piece of it dangling and visible in our own universe?

[Chuck Nice]

Yes, that we're observing what we're actually observing, but it's still a mystery. Like, you know, are there mysteries that are observable that.

[Neil DeGrasse Tyson]

Oh, I got it, Chuck. I'm gonna re. I'm going to recast your question. You ready, Chuck?

[Chuck Nice]

Okay, go ahead.

[Neil DeGrasse Tyson]

Are there deep mysteries in our own universe that could themselves be evidence of a multiverse, and we have yet to put the two together? How's that, Chuck?

[Chuck Nice]

That's what I'm saying.

[Neil DeGrasse Tyson]

That's not what you said. You mangled it. So mangled it.

[Chuck Nice]

But I didn't mangle it enough that you didn't know what I was saying.

[Max Tegmark]

And I will answer it with a resounding yes. Okay, take dark energy, for example. We all know by now that we have no clue what 95% of our universe is made of. And most of it is made of this weird stuff called dark energy. And what's really odd about it is when you work out exactly how much there is in the sort of most natural units of measurement that we would do in physics, we get this number, which is 0.00000 with 123 zeros and then a one. And we wonder, like, why is that? It turns out if you look closer, that if you have a little bit more, we would all be dead. Wouldn't be any galaxies actually ever formed. And if you had less, so this was a bit negative, we would be inside of a black hole by now and also not having this conversation. So why is it that our universe was so fine tuned that the amount of dark energy was dialed in to just that very special value that let us have this conversation? That is one of those mysteries, Chuck, I think that you're fishing for here. Some people said, well, tough luck. Sometimes we're just lucky. Let's just be grateful for it and shut up. Other people said, maybe this is evidence that we were designed either by a divine being or by some simulator who tuned our universe especially to be able.

[Neil DeGrasse Tyson]

To have life in the parents basement. They did this. Yes.

[Max Tegmark]

But then if you actually have this thing with space being very big, with parallel universes, with all sorts of different values of that knob setting in different places, suddenly you have an actual simple explanation for this. The picture you get then is that the bigger space is like the Sahara desert. It's mostly just a barren wasteland with no galaxies. But in a few places now, that knob is set just right and you have an oasis where there is life and there are galaxies and there is star talk, you know, and surprise, surprise, of course that's where we're gonna be having these conversations.

[Neil DeGrasse Tyson]

Well, just to be clear, it's not that it was set that way. It's that if you have an infinite or a huge number of these universes where the knobs are set at random, one of those random knob settings will be the right combination for us.

[Chuck Nice]

It's like tuning your dial up and down. What used to be radio kids, There used to be a thing, used to be this thing called radio guys, where you would actually tune, tune your dial and like most of it was just white noise and empty. But every once in a while you will come across somebody talking or some music or something like that.

[Max Tegmark]

Exactly.

[Chuck Nice]

Oh, that is freaking Brilliant. God, I love science. All right. Okay.

[Neil DeGrasse Tyson]

Keep going.

[Chuck Nice]

All right, here we go. Here we go.

[Neil DeGrasse Tyson]

We got just a few minutes left. See if we can squeeze them all in.

[Chuck Nice]

Here we go. This is Woody, and Woody says, what are your thoughts on how a multiverse could actually begin with? Would each one require a Big Bang? And how many of those would end up with a Chuck being possible?

[Neil DeGrasse Tyson]

Okay, the Chuckiverse. Yeah.

[Chuck Nice]

Yeah. That ain't. Whatever.

[Neil DeGrasse Tyson]

Yes. So, Max, does everyone have a Big Bang just like us? That's a great question.

[Max Tegmark]

Yeah, so I've actually had a total rethink about the Big Bang concept, because first I was taught that that's the beginning, and now it's pretty clear. If you take inflation theory seriously, you should think of the Big Bang just as the end of this crazy, creative inflation process. In our little part of space, when things calm down enough that you can make galaxies and involve a Neil and a Chuck, in other places, it keeps going. So even if you have only one bang, but it keeps going ad infinitum, you will end up having many, many different regions where it stops. And you get what we would call a Level 1 multiverse with the universe. So all it takes is ultimately one bang to get it all. And if you have each one of those places where it stops being actually infinite, then no matter how unlikely it is that you, Chuck, arise. Because the particles started out in exactly the right configurations for your mom to meet your dad and all of that. The probability wasn't zero because it happened here. And you're rolling the dice infinitely many times now. Right. So it's guaranteed.

[Chuck Nice]

Well, there you go. And by the way, both my parents lost on that bet. So. On the roll of that dice, by making you.

[Neil DeGrasse Tyson]

Is that what you're saying? Okay. All right.

[Chuck Nice]

Believe me, I was not a good kid. All right, keep it going. Here we go. This is Cameron Bishop. Hello, Max. Hello, Neil. I've always been curious. Is it flawed to ask what's between these universes? Is that measurable? That's a great question.

[Max Tegmark]

So between the different level one multiverses and the level two multiverse, there is still space, but that space in between is still doing this inflation thing and doubling its size over and over and over again in regular intervals. That's why it's impenetrable. Because if you start flying through, go for a while, and now you're still farther away from where you're supposed to.

[Neil DeGrasse Tyson]

Go, it's expanding faster than you can gain distance through it.

[Max Tegmark]

Exactly.

[Neil DeGrasse Tyson]

Exponentially. Okay. All right.

[Chuck Nice]

That's Great. That's super cool. All right.

[Neil DeGrasse Tyson]

But in the quantum multiverse, they're actually whole other space times. It's not one space time system. Right, yeah.

[Max Tegmark]

The quantum multiverse, the Level 3 lives in the bigger space we call Hilbert space, which may even have infinitely many dimensions.

[Chuck Nice]

So I hear the rents there out of control.

[Neil DeGrasse Tyson]

The Hilbert space.

[Chuck Nice]

Yeah, the property values are just off the charts in Hillberg. Something has to be done. Hilbert, dammit.

[Neil DeGrasse Tyson]

So what would you call what was between those quantum universes?

[Max Tegmark]

In the quantum case, it's much more tricky. When quantum mechanics was first invented, people didn't know about this phenomena called decoherence. It was only discovered by Hans Dieter Tse in 1970, and he should be more famous than he is, which is a kind of censorship mechanism that explains why we don't experience all those other weird quantum realities if they're actually there. Basically, what comes out of the math is that these quantum superpositions that they're called, they only survive as long as they're kept secret. And whenever something gets really big, air molecules bounce off, photons bounce off, and the secret is out. It's like you tell a friend, they tell a friend, and so on. That's why big things like us always seem to only be in one place at once. And we can only experience and measure quantum weirdness with tiny things that can keep their properties secret.

[Neil DeGrasse Tyson]

So, Chuck, time for that last toke on that pipe?

[Chuck Nice]

Yeah, man, I'm telling you right there, that's. Wow, that was cool. What's it called? D what now?

[Max Tegmark]

Decoherence.

[Chuck Nice]

Decoherence.

[Neil DeGrasse Tyson]

No, here's Chuck. When your kids are babbling on and you don't know what they're saying, stop being decoherent.

[Chuck Nice]

Yeah, don't be decoherent.

[Max Tegmark]

Okay.

[Chuck Nice]

You quantum dummy.

[Neil DeGrasse Tyson]

That's worse than incoherent. You are decoherent.

[Chuck Nice]

You are decoherent.

[Max Tegmark]

Yeah, they're just decohering the whole conversation.

[Neil DeGrasse Tyson]

Chuck, give me one last question and see if Max has a sound bite in him to answer, because that's all the time we have left for it. Go.

[Chuck Nice]

Okay. This is Jay Hunt. Greetings, Neil and Max. This is Jeff from Titan.

[Neil DeGrasse Tyson]

My question is Titan, the moon of Saturn. I guess. Okay.

[Chuck Nice]

Yeah, you gotta love that, right?

[Neil DeGrasse Tyson]

My question is that means it's full of methane gas. Just so you know.

[Max Tegmark]

Gotta cut down on those beans, man.

[Neil DeGrasse Tyson]

Yeah, watch out for the beans.

[Chuck Nice]

Right?

[Neil DeGrasse Tyson]

Go on.

[Chuck Nice]

My question is, is a new multiverse created every time we make a this or that decision? So the idea that the infinite number of possibilities are not actually Possibilities until we make one of those possibilities.

[Max Tegmark]

Fantastic question about the Level 3 multiverse. Basically, if you make a snap decision that you're really torn about, right. What ends up happening might come down to the position of a single little calcium ion somewhere in some synaptic junction. And depending on where it is off your brain.

[Neil DeGrasse Tyson]

Yeah.

[Max Tegmark]

Off the things go. And you end up with a completely different pattern. And either you decide to say yes to that date and live happily ever after, or say no and do something different, Right? So that can. A micro superposition can get amplified into something that's so different macroscopically that this decoherence thing comes along and makes these two things really, really separate. So in that sense, yes, when you make a decision that really could have made both ways, you are, in a sense, if the level 3 multiverse is real, creating two parallel realities are equally real. And each one of you is only, of course, aware of one outcome and is going to think that's all that happened.

[Chuck Nice]

Oh, my God. Ooh, that is crazy.

[Neil DeGrasse Tyson]

I love that.

[Chuck Nice]

That is awesome.

[Neil DeGrasse Tyson]

I love that.

[Chuck Nice]

Oh, my God. Oh, right now.

[Neil DeGrasse Tyson]

So it means you created another Chuck, but you're only this Chuck. And so that's what, you know, that.

[Chuck Nice]

Other guy is actually having, and he's having.

[Max Tegmark]

I try to think about that every time I get a parking ticket. You know, that there's some other parallel universe where I didn't. But then I think a bit more and realize there's another parallel universe where I got towed. You win some, you lose some.

[Neil DeGrasse Tyson]

All right, Max, we got a call at quits there. It's been a delight to have you on. It's always great to talk to you and probe your brain for all the fun stuff that you're thinking about. So thanks for being on StarTalk, Chuck. Always good to have you.

[Chuck Nice]

Always a pleasure.

[Neil DeGrasse Tyson]

All right, this has been StarTalk Cosmic Queries, the Multiverse edition. Neil Degrasse Tyson, bidding you to keep looking up.

[Unknown Announcer]

Hanaday presents. In the red corner, the undisputed, undefeated weed whacker guy, Champion of hurling grass and pollen everywhere. And in the blue corner, the challenger, Extra strength adity eye drops that work all day to prevent the release of histamines that cause itchy allergy eyes. And the winner by knockout is Patternay. Patternay. Bring it on.