COSMIC QUEST: An Interview with Physicist Max Tegmark Part Two

As a restless teenager, the Swedish-born physicist Max Tegmark wrote code for a shareware game that made him enough pocket change to travel the world. As a brash young theorist he made the cover of Scientific American in 2003 with his wild ideas about the multiverse—including the claim that an identical copy of each of us lives and breathes out there. (Tegmark even says he can calculate the minimum distance to your double.) Now an MIT professor of physics, he recently rallied Stephen Hawking and other luminaries to warn that stumbling into the technical singularity—the point at which machines become more intelligent and nimble than humans—could be catastrophic. All that and more are covered in his first popular book, Our Mathematical Universe: My Quest for the Ultimate Nature of Reality (2014).

On June 8 Max Tegmark will be the keynote speaker at the 73rd Annual Conference of the American Humanist Association in Philadelphia. Below is part two of the interview the Humanist’s science and religion correspondent, Clay Farris Naff, recently conducted with Tegmark. Click here to read part one.

Our observable universe as seen by the Wide-field Infrared Survey Explorer (WISE). Image Credit: NASA/JPL-Caltech/WISE Team The implications that you draw from the possible existence of a multiverse are rather surprising, to say the least. Perhaps the most surprising is the assertion that out there, somewhere, is an identical copy of each of us. You suggest that they are indistinguishable, and so our sense of ourselves being localized is really an illusion. [caption id="attachment_8244" align="alignright" width="248"]Max Tegmark Max Tegmark[/caption] Tegmark: It’s certainly true that if space is actually infinite and, moreover, space is filled with stardust distributed randomly, then, logically, even though the probability might be small, the atoms will arrange themselves into a planet that looks like Earth with a person that looks and feels like you. The probability isn’t zero; you’re here, and if you roll the dice infinite times it’s guaranteed to happen again. That is a dizzying thought, but we don’t have the right to reject ideas because they feel weird. If there’s anything we’ve learned as scientists so far, it’s that the ultimate nature of reality, whatever it is, is very different from how it first seems. Well, that’s certainly true. A solid object, we now know, is mostly empty space, with electromagnetic force maintaining resistance to one thing passing through another. But here’s a question your idea prompted: If one did carry out a so-called quantum roulette, would it give one knowledge with a certainty of an event in another universe? If you survived, you’d know that an identical copy of you somewhere else is dead. Is that sort of knowledge permissible? Tegmark: A better way of learning about the Level III multiverse, which is what your question addresses, is to try to build really big quantum computers. There is a great effort under way to do precisely this. The quantum computer in essence [treats] these parallel universes as a computational resource. We have parallel computers now that run 10,000 times faster by having 10,000 different processor cores that do things at the same time. Here we can, in a certain sense, do things in parallel in these myriad parallel worlds and calculate in one second something that would take longer than the age of our universe to do here. If we can succeed and actually build a machine that can do that, I think physicists are going find it much harder to dismiss the idea that these other worlds are actually real when they are doing something useful for us. Doesn’t that create paradoxes? Einstein taught us that information never travels faster than the speed of light in a vacuum. But here it is leaping across universes! Tegmark: You might think it creates paradoxes, but actually it does not. You can prove that quantum computers would never violate the principle that information can never travel faster than light. Peter Shor, my colleague at MIT, has discovered that despite all the limitations on what you can do, it turns out you can nevertheless use them to solve certain problems. It was one of the most spectacular theoretical insights in recent times. That’s one of the reasons there is such a huge push in industry to actually build these things. You can never know for sure in advance which philosophical ideas will actually turn out to be useful. There are so many things you might be tempted to dismiss that later turn out to be the basis of technology. This is one example. Another, older example comes from Einstein.  Imagine someone had sent in an application to the National Science Foundation, saying, “Hey, I would like to get some money to think about the nature of time. I couldn’t get a job in physics, so I’m working in a patent office, but send me some money anyway.” Would that get funded? And yet, it was exactly because he wanted to think about the nature of time that Einstein realized that E=mc^2, which gave us nuclear power. Sometimes basic research turns out to be very, very useful, even though there would be no way to predict it. I think this applies even to things we’re talking about now related to the multiverse. In the documentary film Particle Fever, about the Large Hadron Collider, an economist at a press conference asks, “What will be the payoff of this $10 billion investment?” The physicist just chuckles and says, “I have absolutely no idea. We’re pursuing something we can’t know in advance.” Tegmark: And you could have asked exactly the same question about a hundred years ago when people were trying to figure out how atoms work and came up with quantum mechanics. It seemed completely useless, and yet, that’s precisely what’s given us the transistor, the integrated circuit, computers, cell phones, and a large fraction of our GDP. Turning to another matter, in your book you claim that the ultimate, simple reality is a mathematical object. Could you briefly explain what that means? It’s not an object like a tree. What is it like… if anything? Tegmark: When we ask what kind of properties nature ultimately has, it seems like things around us have all sorts of non-mathematical properties. For example, there’s a groundhog that lives in our back yard. Its properties are cuteness and herbivorousness and shyness. They don’t sound mathematical, right? But if I look inside, I see a large collection of electrons and quarks. And what properties does an electron have? Minus one, one-half, one, and although we physicists have coined geeky names for these properties, like charge, spin, and lepton number, the electron doesn’t care what we call them. The properties themselves are just numbers, mathematical properties. The same goes so far as we can tell for all the particles that make up our world. So, in that sense they are mathematical objects. What about space itself? What properties does space have? 3, its dimensionality, for example. Space doesn’t care what we call it. The property itself is a number. If it turns out that nothing in our world has a property that is nonmathematical, then by definition it is a mathematical object. If that’s true, I think it is very good news for science. I mentioned earlier that we keep underestimating our ability to figure things out. The reason we’ve been so much more successful than we thought is not just human creativity but because nature kept giving us all these wonderful mathematical clues in the form of patterns and regularities that we could capture with equations. If my guess is right, and it’s all mathematical, then we’re not going to hit a roadblock where we can’t understand. Everything is intrinsically understandable, and we’re only limited by our own imagination. From a humanistic perspective, it’s a much more optimistic scenario. I want to ask you about the last chapter of your book, where you make some vigorous pleas for us to come together and address some of the threats to our existence. This seems a little odd in some ways coming at the end of a book that has told us that we exist in multiple iterations across an infinite multiverse. Why does it matter? For example, if a large meteor strikes the Earth and wipes out civilization, won’t it just continue on somewhere else? Tegmark: First of all, we don’t know for sure if there are any copies of us, so even if there is a small chance that all life will end forever, that’s a terrible thing, and we should really take it seriously. Second, even if there are other versions of us, the kind of decisions we take here will be similar to what the copies of you elsewhere will make, right? So, it’s important that our thinking process is not flawed and self-destructive. As I’ve said, one of the key things we’ve learned is that we’ve totally underestimated our potential in the humanistic spirit to understand our world and to flourish. We’ve learned through modern science that we don’t just have tens or hundreds of years at our disposal, which many of our ancestors thought, but potentially billions or trillions of years, and we have at least 10^57 more volume for life. So there’s just this incredible future potential. There’s also nothing in the laws of physics that prevents life from spreading from our planet and making much of our universe come alive. Yet, we pay a pathetically small fraction of our attention to this long-term perspective. To give a single example that sort of says it all, there are more people on this planet right now who have heard of Justin Bieber than have heard of Vasili Arkhipov, even though of these two guys the one who single-handedly prevented a Soviet nuclear attack during the Cuban missile crisis was not Justin Bieber. What kind of priority is this? That’s why I decided to include this last chapter, to bring us back home and say, “Look, we humans have this incredible potential. Life has an incredible future potential, yet we keep playing Russian roulette with our entire civilization again and again. That’s not a very solid long-term plan for success. I want to encourage people to step back and think big about what we can actually do to make the most of this potential. One place where I really differ from Lawrence Krauss, for example: I do not share the pessimism he exudes in the notion that we’re all completely pointless, and nothing we do matters. I couldn’t disagree more. Yes, we’ve discovered that reality is much bigger than we thought. But if you get shipwrecked on some island, what would you prefer—to find that you’re actually on a continent or that you’re on some puny little island that’s fifty yards across? We’ve discovered that reality is bigger than we thought. That’s good! We have more potential. Second, we have absolutely no clue how rare life is out there. I make a quantitative argument that we’re actually the only life with telescopes in our whole observable universe. That doesn’t make us insignificant; it makes us extremely significant. And this is really at the core of humanism as I see it. It’s not our universe that gives meaning to us, but we give meaning to our universe. If we’re so obsessed with Justin Bieber that we annihilate all life because we can’t be bothered to be careful, then our whole universe loses its meaning. Max Tegmark will be the keynote speaker at the American Humanist Association’s annual conference on June 8 in Philadelphia.Tags: