Reflecting on strange science

Case physicist goes where no scientist has gone before

Friday, October 21, 2005

John Mangels

Plain Dealer Reporter

As a boy in the early1960s, Lawrence Krauss saw an episode of "The Twilight Zone" in which a little girl accidentally wandered into another dimension. Her rescuer was a neighbor who happened to be a physicist, and who figured out what had happened to the child. The show helped nudge Krauss toward his future profession.

Today, Krauss is a famous physicist and author who teaches at Case Western Reserve University. Though he's never saved anyone from an extra dimension, he's been thinking a lot lately about the scientific basis for their possible existence, as well as popular culture's fascination with the idea.

The result is Krauss' newest book, "Hiding In the Mirror: The Mysterious Allure of Extra Dimensions, from Plato to String Theory and Beyond," to be published Monday, October 24 by Viking.

Plain Dealer science writer John Mangels interviewed Krauss recently about the book and his other activities.

Q: Your previous books have dealt with basic physics, the physics of Star Trek, dark matter, and the evolution of the universe. Your latest one is about extra dimensions. Why did you choose that topic?

A: There is a theme in some sense in my writing that's always there, I hope, which is somehow trying to connect what's happening in science to things people are interested in in cultural aspects of life. What got me interested was this notion that people have been fascinated for a long time in the thought that there might be something else out there beyond what we can see. And science has validated that in many ways, but I don't mean metaphorically, I mean literally. I just thought of literature - "The Lion, the Witch and the Wardrobe, and "Through the Looking Glass," which is part of the reason why it (the book) is called "Hiding in the Mirror." I remember when I was kid, people may think I'm crazy but I remember I used to look in mirrors sometimes and try to look around the corner and wonder what there really was in that mirror - if there was another world in that mirror. I suspect a lot of people have had that (thought) one way or another. It's a central part not just of people's imaginations and in literature, but in a sense it's also the basis of religion - the notion that there's a spiritual world beyond what we can experience. What fascinates me is that scientists have continued to think about this notion and reinvent it one way or another for some time. And it's really hot right now in physics. I thought (the book) would give me a way to put that in perspective. I write books to learn as well as to explain, and one of the things I wanted to learn was about the history of this idea in science and also in art and literature. The notion that extra dimensions might have affected the way people think about representing the physical world in art was fascinating to me. So it was a combination of that, plus I frankly wanted the opportunity to put in perspective a lot of the hype that's happening in the popular media over things like string theory, so that people can see why people are interested. But a hundred years from now, string theory may be just as curious an artifact as some of the weird ideas in the 19th century about extra dimensions.

Q: We'll get to string theory in a minute, but you did a pretty extensive historical review of the ways people have looked at the spiritual world or heaven or however else people think about what's out there. You found that writers and artists got to the idea ahead of physicists.

A: Oh certainly, and I think they still may be ahead of physicists. I was kind of amazed, going back to the 15th Century, to see the appeals not just to a metaphorical spiritual world, but to an extra-dimensional spiritual world. What I really focus on is the interest in the late 19th Century in England and France and other places. There, they really were a few decades ahead of the first inkling in modern physics that we might want to think of extra dimensions. I hadn't really appreciated when you see the cubist paintings exactly what was going on there, these Picasso paintings and others where it doesn't look like it's a person - you see different perspectives, projections in the same painting. There was a lot of discussion at the time of doing different three-dimensional projections of a four-dimensional universe, which is actually kind of amazing. I'm a big fan of art and it was illuminating. One of the first things I did was go to one of my colleagues in art history to get some direction of where to go.

Q: You talk a lot about that in the book, Picasso and Dali and even the suggestion that Jackson Pollack was trying to represent virtual particles popping in and out of existence.

A: I don't know if he was or not. That's been said. But Picasso was painting at a time when the entire group he was working with was strongly influenced by Poincare, who was writing about extra dimensions. And his contemporaries as artists were talking about that. Marcel Duchamp specifically talks about trying to portray a fourth dimension. I view science, art and literature as really tied together, as giving us a new perspective of our place in the universe. I like to learn about those connections, and learn what's driving the other people who are working hard to add some enlightenment and also make the world a more exciting place. And I'm always fascinated by that interplay of ideas and wondering whether a predilection in one area of human intellectual activity filters in any way, even just in terms of the background thinking, into another area. I certainly see that in one direction - the scientific ideas filtered down in one way or another into the literature and artistic world. But usually they're distorted by the time they get there, and in this case they were. The fascination at the turn of the (20th) century with a fourth dimension had absolutely nothing to do with Einstein's fourth dimension.

Q: You say in the book that you believe people are "hardwired" to long for something beyond the physical world. Can you talk about why that might be the case?

A: I don't know why. I try not to ask "why" too much as a scientist, but maybe as an author I do. It just seems to be a fact. I imagine when human consciousness first arose, the world was a terrifying place. It was hostile. There were predators, danger, natural events that were inexplicable. At every turn one has to use one's emerging consciousness to try to conquer that. But at the same time to feel safe, it's natural to kind of expect that you're not alone in the world, that there is some bastion of safety, someone looking out for you if necessary. People have argued that we're hardwired to believe in God. In a sense, we're hardwired to believe in a better place because the world, even though scientists try to make it a better place, is still dangerous and scary.

Q: Let's begin to tiptoe into the physics of your book. The scientific interest in extra dimensions really stems from the attempt to better understand gravity and to find a mathematical framework that unites gravity with the other forces of nature - electromagnetism and the strong and weak atomic forces. Can you explain how that search led to the idea of looking at extra dimensions?

A: I'll try. Part of the fun for me in this book was to be able to present a sweeping history of 20th Century physics, talking about the experimental discoveries that had led people to think about this. Some physicists are trying to get people to believe in 26 dimensions or 11 dimensions, and all of these notions sound so esoteric. What's amazing is that, step by step, by a series of experimental results either done in weird chemistry labs, as I talk about with Michael Farraday, right through to the experiments that are done with computers and high energy accelerators, somehow, out of all that data, physicists extrapolate to predict these exotic possibilities. You know, extradordinary claims require extraordinary evidence, as a version of what Carl Sagan said. At some level, if we're going to claim we're interested in these ideas, we should show what the progression is. And it's a long progression. It wasn't as if someone just said one day, "Let's come up with extra dimensions - yeah, isn't this a neat idea, let's get government money to think about this." It sounds like, "Oh well, we're drinking some wine today, let's think about extra dimensions." The idea has come up time and time again. The point is that gravity in one way or another is quite different than the other forces in nature. After all, gravity is the theory of space and time. And it's had a hard time fitting in with the other forces, which are not theories of space and time. There are four forces in nature: the electromagnetic force which is responsible for most of the things we experience, like the light we see; the strong force and the weak force, which are responsible for most of the processes that hold the nuclei of atoms together and the processes that power the sun; and then gravity, which by the way is far weaker than all the rest, by orders of magnitude.

Q: That's hard for people to imagine.

A: Yeah, because when you wake up in the morning, the first thing you feel is gravity, right? The thing that's hard to understand is that the reason we feel gravity is that every atom in our body feels the gravitational effect of all the atoms in the earth. But the (individual) gravitational attraction of each atom with every other atom is so small we could never possibly measure it. Richard Feynman gives a very good example. He said if you take a friend to the top of a tall building and push them off - well, maybe not a friend - if you're 200 feet up, it takes gravity all that way to accelerate the body, but it's electromagnetism that stops it. The reason you don't go through the concrete is that the electrons in the atoms of your body are repelled by the electrons in the atoms of the concrete. You don't even make a dent. Electromagnetism can stop you in a fraction of an inch, whereas it takes gravity all that way to accelerate you. It gives you some sense of the relative strength of those forces.

Q: So electromagnetism trumps gravity.

A: Except, ultimately, when you get to very, very, very small scales. The size of the scales we're talking about, compared to the size of a nucleus of an atom, are like the size of a nucleus of an atom compared to the size almost of our galaxy. We're really talking about small scales, which is why we're not probing them experimentally right now. The theory tells us that if we extrapolate what we know to that scale, something crazy must happen. In fact, gravity becomes strong at that scale and you can't ignore it any more. When we do calculations of atoms and how the sun works and how we work, you can ignore gravity. Gravity matters on two scales of the universe. One, on the very large scale, because even though it's very weak, when you build up all that matter, it's dominant compared to the other forces. And on very small scales, it's important. This is a long answer. But shortly after Einstein came up with his theory of gravity - general relativity - people tried to think about how you might merge it with the other forces in a better way. And the first proposal was by these guys (German mathematician Theodor) Kaluza and (Swedish physicist Oskar) Klein, who said maybe the reason gravity's a theory of space and time and the other ones don't appear to be is because the other ones are theories of space, but not a space we can experience. That somehow the existence of electricity - at that time just two forces were known, electromagnetism and gravity - they looked mathematically very similar. One's a theory of space and one isn't. Perhaps it wasn't too surprising that people thought if you have an extra dimension that we can't see, and you have a theory of gravity in five dimensions and not four, then that extra component of gravity, the mathematics of it would look identical to electricity and magnetism. It was a beautiful theoretical discovery.

Q: It turned out to be far ahead of its time.

A: In a way it was far ahead of its time. It was also behind the time in a sense because we later discovered these other forces in nature and it wasn't a theory of everything. But the idea mathematically was really far ahead of its time. It took Einstein a while to accept it. It was two years before he passed on the publication which was sent to him for review. Twenty years later he wrote a paper which was virtually identical. He didn't copy it but he and a colleague were thinking about it and came up with a proposal that was virtually identical. By that time, the 1930s, when Einstein proposed it, it was already too late to think of that as a unified theory of everything because we already knew about these other two forces of nature. But after we discovered the other forces and started to learn about them, the voyage of discovery is fascinating. I hope that people who read the book really get an appreciation for the series of little steps that people took. People taking Geiger counters and particle detectors and climbing to the top of mountains and trying to discover new particles. It's amazing the sort of personal quest that step by step led us to where we're at today, and led us to a set of theories that by the 1970s - and one of them was vindicated in last year's Nobel Prize - we now have a really good theoretical description of the other three forces in nature and gravity, but there are problems. Gravity continues to haunt us. The story that I tell in the book is in the process of trying to understand one of those forces in nature, the strong force, which is perplexing because in the 1960s, every time we looked into an accelerator a host of new particles would come up and it was a zoo. It looked like the world was complex and inexplicable on small scales. Physicists for a decade were flailing around trying to figure out what to do. They came up with this weird idea that maybe you could understand all of these new particles if maybe they were manifestations not of fundamental particles but of this vibrating string-like structure. It turned out to be completely wrong, and it's an example of when another new idea comes along and explains the data and it's simple, it can supercede it quickly.

Q: What part of it was wrong? You're not saying that string theory as a whole was wrong?

A: No. The idea that one can understand the strong force between the particles we measure as if those particles were directly a manifestation of a string, and the force could be understood as a force between strings - that was completely wrong. The theory that supplanted that was the realization that protons and neutrons and the particles that people thought were fundamental were not directly manifestations of strings but rather were made up of objects called quarks, whose interactions one could understand in terms of a theory which looks very similar to electromagnetism, and which could then explain all the data. One of the things that was really wrong about this (string) theory was it predicted a new kind of particle which ... a decade later people said, you know what, that kind of particle would explain gravity.

Q: This is the graviton?

A: Yeah. And maybe we had the right answer but the wrong question. Maybe we should be thinking that string theory is not a theory of the strong force, but maybe would lead us to a theory of gravity. Certainly by the 1980s people were saying maybe this is not only a theory of gravity, but a theory that allows gravity and quantum mechanics, the other big discovery of the 20th century, to finally merge. Because the big problem that was understood to exist with gravity from the time quantum mechanics was developed in the 1920s and '30s, was if you apply quantum mechanics principles to just general relativity, you come up with nonsense. The numbers you get are infinite. String theory, which had been developed to try to explain other infinities in the strong interaction (which we later learned were solvable by other means) gets rid of infinities and it could be a theory of gravity, so maybe it's a theory of quantum gravity. And it turns out that it's only a theory of quantum gravity if you have extra dimensions.

Q: Explain what you mean by quantum gravity.

A: Quantum gravity is a theory that would be the theory where quantum mechanics and gravity would work together, at that very small scale, so small we can't probe it. The other thing I should have said is what amazes me is that physicists in the 1960s were even willing to consider this. String theory, which they'd been driven to to try and explain all this data and the strong interactions, only worked in 26 dimensions. And it amazes me that people were willing to say, OK, I'll accept this even though it implies 22 other dimensions that we've never observed, just to solve this problem. But physicists were desperate. So here's this theory that could be a theory of gravity and quantum mechanics, and it seems to require extra dimensions to exist. And lo and behold, it turns out that maybe there is a way to embed the other forces of nature in some unified framework. That idea happened around 1984. That's when string theory in its modern form really took off and people started talking seriously about the Theory of Everything. This is supersymetric string theory. It was first shown that, in principle you might get rid of all the weird infinities in quantum gravity in a consistent way, and there was a possibility you could embed the other forces of nature in the same theory, in not 26 dimensions but maybe 10 or 11. That is when the hype began. That is when the physicists working on this theory said we have a model, a theory, which in principle can explain everything. There was a great deal of excitement in that community, even though it dealt with a theory which was at its basis far removed from experiment. It was experimental ideas that had led to the development of the theory, but the theory itself could not yet make any direct predictions that could be probed experimentally.

Q: Let's stop there and talk about extra dimensions and experimentalism versus theory. The first thing that people might wonder is, whether there are 26 or 11 or 5 extra dimensions, where are they? Why can't we see them?

A: That's a very good question. I think it's the first question people should ask. The very first thing I want to say is we have no direct evidence of any sort that any extra dimensions beyond the four we know - the three of space and one of time - actually exist.

Q: But you've written a whole book about the prospect that they do.

A: We have tantalizing reasons to think they might. My book is more to show that this recent fascination is part of a long-term fascination and may reflect something more in our minds than in nature. I don't know the answer. I wrote this book as an agnostic and I wrote it for people to say here's why some scientists are fascinated, why we should be skeptical, and how mathematics and the real world come together. People can, hopefully with the perspective I provide in the book, decide for themselves whether this all seems so hokey as not to believe, or whether it's so fascinating they would expect a new discovery around the corner. But we do not see any extra dimensions. If they were obvious, when you threw a ball, every now and then it would disappear into a dimension other than the ones we see. So we know that, if there are extra dimensions out there, they're hidden in one form or another.

Q: Right now our thought that they might be out there is strictly based on mathematical calculations and theoretical predictions?

A: Mathematical calculations and tantalizing hints based on potentially solving problems in the worlds we know suggests that if these extra dimensions exist, and they're hidden, that would be one way to solve the problems. We don't hide them as a way to keep our theories viable. It turns out that if they're hidden, that might naturally explain some of the things we see. The question is how could an extra dimension be hidden. I mean, my goodness, the three dimensions and space are quite obvious when I look around this room.

Q: What are those three dimensions? A; Height, width and breadth. And there's a fourth, which is time. One of the things I talk about in the book is that it wasn't Einstein who realized this. After Einstein developed special relativity, one of his math teachers, Hermann Minkowski, realized the framework he'd established, Einstein's special relativity, could be understood if space and time were tied together in a four-dimensional framework. He (Minkowski) gave a very famous lecture in which he declared, henceforth, space and time themselves will sort of fall out of existence and we'll only think of space-time. And he was right. The fact that time is the fourth dimension caused incredible interest in the popular community as well as in science. A lot of the modern science fiction was based on these four dimensions. The fact that time was the fourth dimension in the science fiction literature and among artists as well was somehow interpreted as there are four dimensions of space. So you see this notion that "Einstein said there's a fourth dimension." I begin the book with The Twilight Episode (about that), which was one of my favorites because it scared the daylights out of me when I was a kid.

Q: It may have put you on the path to being a physicist.

A: Yeah. In fact I talk about a recovered childhood memory. When I began the book, I knew I wanted to think of extra dimensions, and I remembered this episode that terrified me when this little girl fell into this extra dimension in "The Twilight Zone." I decided I would find it. It turns out the hero of that episode is a physicist. I had not remembered that at all. When I saw it, I suddenly remembered thinking, my gosh, this guy has knowledge that everyone wants to know, he's a hero - I want to be like that one day. As I say, no one's ever come to me in the middle of the night seeking help from a physicist except for students the night before an exam. I haven't pulled anyone out of extra dimensions yet. But hopefully I do think one of the reasons I write books is to provide assurance to people of understanding what nature's all about. That's what that physicist was doing for that family. He was explaining to them the way the world works. One of the reasons I write books is to provide an intellectual lasso people can use to pull them out of the morass of ignorance.

Q: Do you ever wonder if extra dimensions are just a mathematical construct, a way to make the equations balance?

A: I wonder all the time, and I hope that's clear in the book. I don't know. I am eternally skeptical. That's what makes me a scientist.

Q: You're more skeptical than some of your colleagues.

A: Absolutely. I've become kind of a national skeptic when it comes to string theory and to some extent extra dimensions. As fascinating as some of these ideas are right now, I also temper that fascination and enthusiasm with the realization that most new scientific ideas are wrong. If they weren't, then science and physics would be easy. I like to think I've come up with some fascinating ideas in my time as a scientist, but some of the most fascinating ideas have been wrong. I accept that. That's just the way the world works. So I suspect that most of the ideas, frankly, that are being bandied about related to string theory and extra dimensions are wrong. There may be a kernel of truth there, because there are some fascinating ideas. But even if there is, I suspect the ultimate theories that we come up with probably will bear very little resemblance to the things we're watching on "Nova" right now with vibrating strings and 10 or 11 dimensions. In fact, one of the things we've discovered in string theory in the last few years, is that strings themselves may not be (the most) fundamental objects. The more we understand string theory, the less we understand it.

Q: Do you ever wonder if there's no bottom to the well, so to speak? That you aren't ever going to find the most fundamental force or object or particle?

A: It's a good question. I've never been convinced that there was an end to physics. That doesn't mean there are turtles within turtles. Each time we peel back a new layer of the onion we have a whole new understanding of the universe. I've always felt that the search is more interesting than the finding - that it's the continual probing to try and understand nature that leads to unexpected new discoveries. I think it's quite possible that the whole effort of string theory itself will lead nowhere. But I expect that out of it will come unexpected discoveries that will be useful. The idea of these extra dimensions that are hidden - when we used to say they were hidden, potentially the original string theory explanation was the same one that Kaluza and Klein came up with (in the early 1900s) is that if you have an extra dimension of space that was curled up so small that you couldn't see it, so small that microscopes couldn't detect it, then it could be invisible. Just like if you took a soda straw, which has two dimensions - you can go around the straw, you can go along the straw - but if the radius of the straw is so small, you can't see the going-around part and it looks like it's just one-dimensional. That was the argument given that if this extra dimension was really small, we would not have been able to probe it by any experiments we've yet done. And maybe there are 22 such extra dimensions, which is what string theorists originally thought, or maybe an extra six or so. That's fascinating. But what really was the kicker that led me to write this book was the realization in the last five years or so that it's actually possible that some of the extra dimensions are large, as large as the ones we see, but could still be hidden. One of my PhD. students contributed that idea. That's fascinating to me, and I'm very happy it got him tenured at a distinguished institution.

Q: Does the idea that there might be large extra dimensions suggest a way to experimentally test for their presence?

A: That was one of the reasons they were developed. One was the realization that you might solve some a problem in particle physics if some of the extra dimensions were larger. But also they offered a tantalizing hope of making the physics associated with string theory (operate) on a scale where they might be detected with the next generation of particle accelerators. By smashing particles together, we may see some of them disappear into extra dimensions, which would be really amazing. Or, we may produce new kinds of black holes, little tiny ones, that do strange things, some of which are to release energy into extra dimensions. So those hosts of phenomena are fascinating if they're true. They also offer the other tantalizing possibility, which to me is even more exotic and interesting because it relates more to the imagination and what happens in science fiction - that a whole other infinitely large universe is just maybe a little bit away from us in that extra dimension. Maybe a millimeter away in an extra dimension there could be a whole other space, with galaxies, maybe even universes with different laws of physics. You could literally hide a whole universe of physics and life in these extra dimensions if they're large. I have to tell you that of all the things I'm skeptical about, I'm most skeptical of these large extra dimension ideas. I think they're fascinating but they stretch the limits of string theory, and I would argue they tend to go against the direction that experiments are already leading us. One of the things we've discovered experimentally in the last 30 years is, not only these four forces of nature, it turns out the strength of the four forces varies with size. The great discovery for which the Nobel Prize was given last year is that the strong force actually gets weaker when you get smaller and smaller distances (between particles).

Q: That seems counter-intuitive.

A: It does, because when you bring two (charged particles) together the force between them grows. Or two magnets. It's very counter-intuitive, which is one of the reasons it won the Nobel Prize. When experiments vindicated it, it was a wonderful discovery. It also tells us that if electricity is getting stronger and the strong force is getting weaker, maybe there's a scale where those forces have the same strength and the forces of nature might be unified. That idea led to an idea in the mid-1970s, right after the discovery of this aspect of the strong force called asymptotic freedom, called Grand Unification - the idea that you could unify at least the three non-gravitational forces in nature. If you plug the values in from experiment, the rate at which these forces are changing, and you ask at what scale would they all have the same strength, there indeed is one. It's about 16 orders of magnitude, that's a million billion times smaller, than the scale of the size of a proton. In spite of the fact it's so small, people proposed indirect experiments that might be able to probe that scale. It turns out that if Grand Unification was right, then protons - the stuff of you and I, of matter - would not be stable. They wouldn't decay in a short time. They'd decay in a time that's a million billion billion billion times the present age of the universe. As my friend and former colleague Shelly Glashow says, diamonds aren't forever. It's a prediction you can test. If you get a million billion billion billion protons in the same place, then on average one of them will decay each year. That's what these large proton decay detectors with 50,000 tons of water are doing in deep mines around the world now. They're looking for proton decay. By the way, the proton decay detector that was the first one, the most famous one, was right out here in Cleveland, at the Morton salt mine. It was built in the 1970s and '80s. It was built in direct response to this idea of grand unification. Unfortunately the simplest idea of grand unification was shown not to be right because the proton didn't decay in the time it was thought to. But larger detectors are being built. The bottom line is that all of the data that's come in in 20 years since that first idea shows better and better that the forces can come together at a very very small scale.

Q: With the exception of gravity.

A: But the scale where gravity becomes strong is within a few orders of magnitude of that scale. The idea behind these large extra dimensional theories is that that's just an illusion, that in fact the real scale where gravity and these other forces come together is on a much larger scale, comparable to a scale a few orders of magnitude smaller than the size of protons. And that's why we might be able to detect it with the next generation of accelerators. The leakage into the next dimensions gives us an illusion about the scale where gravity becomes strong. The very fact that it's possible to hide extra dimensions is an amazing idea. It's wonderful that you can have large dimensions that are not observable. Our four dimensions are kind of like a surface in a larger-dimensional space. And all the particles and forces in nature are stuck to that surface except for gravity. Gravity can probe the extra dimensions. Even though it's fascinating, it goes against the grain of current data, which tells us that there really is evidence to think that the forces of nature are unified at a small scale and therefore that idea (of large extra dimensions) isn't necessarily needed. As a cosmologist who spends time thinking about the origin and evolution of the universe, you could ask what has this new idea given us? After all, if there are all these extra dimensions, can you do something with them? One of the points is, look, we may not be able to do experiments now that can probe them, but the universe did an experiment that probed them. Because at the very beginning, the Big Bang tells us that everything we observe was once inside a region incredibly small in size. Therefore, if there are extra dimensions, maybe those impact on the very beginning of our universe. In order to probe those dimensions, we have to go to very small scales. The universe itself once existed on those very small scales. So it must have probed those extra dimensions, and maybe there are some remnants leftover in the universe we see that were affected by the physics of those extra dimensions.

Q: Aren't we prevented from seeing back that far by the cosmic background radiation?

A: The cosmic background radiation says that by light we can't see that far back. But maybe there are remnants, maybe gravitons or neutrinos or other things produced in the very early universe, that can give us the signature of those extra dimensions.

Q: But we don't know for sure there are gravitons.

A: We know there are gravitational waves. We don't know that the quantum theory of gravity is right, but there's every reason to believe that gravitons exist. But maybe there's some remnants and maybe we can understand some puzzles of our universe, of why our universe is so uniform on large scales or why there's dark energy, which after all we think may be a remnant of the very beginning of time. The biggest mystery in cosmology is the nature of dark energy. The largest energy that we know of in the universe seems to reside in empty space. There are really good reasons to think that to understand that, we need to understand the nature of gravity on fundamental scales.

Q: Why are they linked?

A: Because this dark energy, this energy of empty space, is producing a gravitational force that's repulsive. It's pushing the universe apart. It's causing it to accelerate, which is the great and surprising discovery of a few years ago. It's remarkable and totally unexpected. And the nature of how empty space gravitates is obviously related to the nature of space and time. So we think that to resolve this nature of why empty space gravitates the way it does, we're strongly suspicious that it involves fundamentally understanding the nature of space and time, which means ultimately fundamentally understanding gravity. So things like that may be remnants for us, may give us an experimental handle on processes that happened at a scale when the universe was unimaginably small that we'd never be able to recreate in a laboratory today. So cosmology may give us the key to these extra dimensions. But what I point out in the last part of the book is that cosmology, remarkably, so far, it hasn't at all. In fact, in spite of all the exciting possibilities that have come up from extra dimensions, every explanation leads to more problems. So right now we're really in the midst of not knowing. Maybe it's weird to write a book about being in the midst of not knowing. But the possibilities are so fascinating and are related to so many things that people have thought about over the last few hundred years, that I thought what a great opportunity to put people in the middle of scientific controversy, and a mystery. The best mystery stories are where you don't know who did it, and that's certainly where we're at.

Q: Do you ever worry that people will say "This is just too weird. I can't get my brain around the idea of extra dimensions"?

A: I think that's likely to happen, especially in the latter part of the book where I talk about some of the complex ideas that are coming around. People may say this is just wild. But at the same time, I want them to have a better, educated understanding of how wild it is. As a famous physicist once said about a bad idea, "This idea is crazy, but it's not crazy enough to be true." I think the question is, when you look at that, will you see why people are motivated to talk about these things, or will you think it's just so ridiculous it can't be true? I hope I give people enough information to at least have some basic opinion in that matter. I think it's important, because there's been so much hype and people really believe that string theory is on as solid a theoretical footing as the strong interaction, or quarks, or any of the other beautiful ideas that have been vindicated by experiment and have led to new physics. And it's not that case at all.

Q: Is it appropriate to call string theory a theory, then?

A: Good point. I was just on the radio debating intelligent design, and people have the wrong idea what a scientific theory is. They think it's like, "I have a theory that Cleveland always puts speed traps wherever I'm about to drive." That's a nice supposition. But a scientific theory is very different. It's an idea that's met the test of experiment and led to further predictions that have been further tested. So it really is on firm grounding. So you're absolutely right. I think in some sense "the string hypothesis" would be a much better way of calling it than "string theory." And "the M hypothesis." Moreover, not just because they haven't been tested. But as I tried to describe in the book, as we try to explore these mathematical ideas, we realize we don't even know the proper formulation. It's not as if we've got this well-defined mathematical theory and we just can't test it. We don't even have a well-defined mathematical theory. We're at the point of probing these fascinating mathematical ideas and trying to understand what they mean, mathematically as well as physically. There are lots of fascinating reasons to think about it. But to suggest we're any further along is wrong. Moreover, as we get further and further along, we're discovering that all these basic things that have been advertised, like strings themselves, may be just illusory. And the weirder thing - maybe dimensions themselves are illusory. There's the proposal - and it's not crazy although it may sound so - that we're kind of a four-dimensional hologram. A hologram, as many people have seen, is a three-dimensional picture. A normal picture, like of a high school class, if there's someone in the back row that you can't see, if you tilt your head you won't see them in the picture because it's a two-dimensional projection of a three-dimensional image. A hologram, if you move your head around you're actually able to see behind the person in front, to see the person in back. It's a two-dimensional stored image that has all the information of a three-dimensional image embedded in it. If you're clever you can extract that three-dimensional information. The claim has been made that maybe it's possible that the physics of an apparent four-dimensional world could really contain all the physics of an underlying five-dimensional world. It's not the projection, it's not just an image, it's really the same thing. We're getting this illusory picture. Whether you decide to call it five dimensions or four dimensions is in the eye of the beholder. It's a fascinating idea. It may be wrong. But if it's true, then maybe even the idea of dimensions begins to melt. And maybe we're just on the wrong track when we try and talk about whether we live in a four or five or 10 or 11 dimensions. It may sound wacky and wild. But what I like to point out is that serious scientists are actually debating them and thinking about what the implications are. Maybe we're right. Maybe we're wrong.

Q: Do scientists who have devoted their careers to these ideas resent your skepticism?

A: Some of them do. I try sometimes to make a point by making a counterpoint. It's fair to say that, in my opinion, there's been too hype on string theory, given what it's produced, which is so far not much. Therefore I try to make strong statements to get people to wake up. Sometimes people object to those strong statements. I quote Ed Witten, who's been one of the leading string theorists, to point out he's not saying that many different things than I am. What I try and argue is that if you're a scientist and you're going to be working 10 or 20 years on an idea, you've got to believe in it. But the thing that makes you a scientist rather than a religious person in that regard is that if the idea is shown to be wrong by experiment or theory, you give it up. You walk away. It's perfectly fine that scientists have strong beliefs in what they're doing. Otherwise you couldn't go in and work 20 hours a day for 15 years on something if you didn't have utter faith it was right. But you're willing to throw it out. So I think one tends to find that people who have been working on (string theory) naturally have a kind of undue enthusiasm about it. Unfortunately in string theory they have been promulgating that undue enthusiasm, in my opinion, on the public. That's why I hold them to task. I have no problem that they're excited by what they're working on, and they may even believe it's doing something. But they've been so effective in arguing it's a theory of everything for so long, when up until now it's been a theory of nothing. I think it's important to add a balance, especially in these times when we're fighting attacks on science, where there are large groups trying to claim there is no difference between science and religion. And by that I don't mean to be pejorative about religion. I just mean that people are saying that science is really an act of faith and scientists are just a different philosophical system. It's not true. Scientists have faith and philosophical systems when they're doing science. But science is based on a well-defined set of steps, and it's limited in its scope and is limited in what it can do. If we start telling people that we believe this is true because it's beautiful, or because some people think it's beautiful, then really does that sound any different than religion? I think the fair answer is no. In writing this book as a skeptic and learning some aspects of string theory and M dimensional theory that I was not fully aware of, there were times when I was taken aback and thought, wow, that's amazing. But just because something's amazing or beautiful doesn't mean it's true. And it doesn't mean it's science either. It's enough to ask the question to see if it's science. As I try and defend science lately against attacks on it, I'm maybe ultra-sensitive to this complaint and comparison that's made between science and religion. I think it's important for us to point out what science is and what it isn't, in all contexts, string theory and beyond.

Q: Even though, as you acknowledge in the book, there's some overlap in sort of a philosophical sense between the concept of extra dimensions and a spiritual world or a heaven.

A: Absolutely. I think that's the hardwiring I'm talking about. It's fascinating to think that there's something more out there than meets the eye - for scientists, that you can do fascinating things in those extra dimensions that you couldn't do in our four dimensions, and for religious people, the same thing, that there's a world of possible phenomena, spiritual, religious, supernatural, whatever you want to call it, that is out there beyond what we can see. Somehow the notion is fascinating to everyone. But I do want to point out the differences.

Q: You talk about attacks on science, "from the classroom to the White House." Why is that happening, and why have you been willing to spend a lot of time away from physics dealing with that?

A: First of all, I happen to believe that science is a vital part of our society in all ways. Science has produced the world we live in, for better and for worse, although I think largely for better. Therefore, it concerns me when I see the potential to take a giant leap backwards in terms of the human rational inquiry of the universe and the ability to use our minds to improve our condition. But also I kind of feel this responsibility as someone who's in the public eye. I spend a lot of my time trying to excite people and explain science to people. Therefore I view it as my responsibility since I have that plank to use it. Part of fighting the attacks on science is to explain to people what science is all about. I'm an educator and I believe that if people are educated, they'll make better decisions. Part of fighting the attack on science is trying to hit the misconceptions people have that cause them to either fear science or misunderstand it.

Q: Do you think the public fears science at this point?

A: I think they distrust it more. I know there was a recent European newspaper poll showed that even in Europe, which is must less distrustful than the United States, that distrust of science had increased by 10 or 15 percent in the last decade.

Q: Why?

A: First of all, we live in terrifying times in general, and there are lots of problems. People look around and see global warming, which in a sense is a result of science because it's a result of industrial activity. But if we didn't have the industrial activity we wouldn't have the standard of living we're living in.

Q: And if we didn't have science, we couldn't measure that there was global warming.

A: Exactly. But the science itself is not bad. Society has to understand the implications of technology of science. You can't properly understand those implications and how to deal with them if you're not honest about the science. You can't make rational decisions about global warming or stem cell research if you base your entire thinking about religious predilections or religious ones. Also, we're dealing with questions that are terrifying: the nature of life, what it means for things to be conscious, the beginning and the end of the universe. People are sometimes rightly concerned. They view that a scientific understanding of things will somehow obviate the religious beliefs that are a central part of their lives. Sometimes it's presented as if it will. I've become much more sensitive in the last year or two as I've been involved in this to the notion that people react out of fear, and if you want to explain something to someone, you're not very successful if the first thing you do is try to tear down all the things they believe. I've noticed, because I've talked with you over time, that you seem to have moderated a little bit on that part of your comments on intelligent design. I certainly have. I have my personal views about religion. But I guess what I've learned is that religion is here to stay. This human need is there, and how it's met, we'll see. I've also come to realize this notion of fear and how to try and best communicate with people. Scientists have tended to be pretty brash and conceited about science and its ability to deal with things. I think we come across often as appearing to argue that science is really everything important, and if it isn't science, it isn't important. I tend to sort of suffer from that as a physicist. Physics has been so successful we tend to sneer at everything else. I think I've become sensitized to that and hopefully can respond to it more. Also, more recently, because of my efforts to try to make sure the church is on the right side, I've had to learn more about where they're coming from - the Catholic church and its position on evolution. So I had to try and appreciate their arguments. I've modified a lot. I don't think I've sold out in that sense. As I've said before, I think offending sensibilities is fine when those sensibilities are manifestly wrong. I won't accept a 10,000-year-old Earth because it isn't. If you feel that's necessary to believe in God, than you should stop believing in God. But really, what you should realize is you don't need that to believe in God. I guess I've just tried to disassociate my personal views a little and understand where people are coming from.

Q: You've worked hard to make esoteric science accessible to the mainstream public. Do you worry that the really far-out stuff, which you could argue extra dimensions is, is just too hard for the lay public to understand?

A: The details aren't too hard, but are too sophisticated. They require too much intellectual baggage. But when I write any book, I don't expect someone's going to come out with a working knowledge. What I want them to understand is the perspective on which that knowledge is based - where it comes from, what assumptions are made, what things can you get excited about. If people get that, that's really all I hope. I don't expect people to come out of this and say I'm going to work on string theory, or that they might understand everything in there. But I like not to appeal to assumption or authority. I want to present things to people if they're willing to puzzle through it. The details, especially of string theory, don't matter that much. People can gloss over it. I want them to see where the intellectual framework comes from, the remarkable things we've discovered about the universe. I just hope I provide a perspective that people can then use to judge what they read in the paper. It's all there if you want to puzzle through it. I like to think I provide explanations that if you're willing to puzzle through it, are clear. I think we owe it as scientists to the public to explain what we're trying to do ... and what we hope to accomplish. After all, we are funded by the public.

Q: Was this book harder than your last one? In that one, you took people on a journey with an atom that was formed at the beginning of the universe all the way to the end.

A: That was extremely hard and ambitious in a different way. I had to learn whole fields of science that I wasn't really knowledgeable in, including evolutionary biology and geology. So for me it was a fascinating intellectual journey. I try to learn something new in every book. I think there's a tendency - and I won't name names - to write the same book over and over again if you write about science. I try to think of a new subject that has some basis in my knowledge ... but will take me beyond the domain where I'm completely comfortable so I can learn something and so the book is new. This book was extremely difficult. It was difficult to get my mind around how I wanted to present this complex subject. Also, since there was a lot of history, I had to read a lot in different areas, including of art and literature. There was a vast body of material I had to conquer .. and then figure out how I was going to put into an interesting perspective. The "Atom" book was a grand scientific tour and I'm very proud of it, but even "The Physics of Star Trek" required me to watch 200 episodes of Star Trek, which is difficult or not, depending on your mood.

Q: Do you have an idea for your next book?

A: There are two I'm considering. I had an idea for a fiction book which I've to convince some publishers to do but they keep wanting me to write non-fiction. I'll write it at some time. It's a fiction story in which science plays a role. It's a mystery story with science as a central part.

Q: What's the non-fiction science book?

A: One book I'm very excited about will be the first time I've tried to tie what I've been doing in newspapers and radio into book form. I'm not at liberty to say all the details, but it will try to follow up what I've been doing in my public campaign for science. It will be a discussion of the role and importance of science in our society, and hopefully a plea for rationality. I hope it will set the basis for a lot of interesting public debates and discussions.

Q: You recently stepped down after having spent 12 years as the chair of the physics department at Case. During that time I think anyone who looked at the department would say you elevated it to national prominence. Why did you step down?

A: There were many factors involved. I was chair for 12 years - a long time. There were still things to do and I thought about continuing to do them. But in the context of where the university was going, it wasn't clear that I could continue to be effective as chair. It seemed it might be better for the department to provide the opportunity for someone else to be chair. Also, there was a hope I could move on and do some other things that might be equally or more exciting, both at the university and within the context of society in general. The most exciting recent thing that's happened is I've moved part-time into the medical school, directing the Office of Science, Public Policy and Entrepreneurship, which is very broad, working with the dean on new opportunities for funding medical science, to connect the medical school to the rest of the university, and looking at public policy issues like intelligent design, evolution, and maybe other things like astrobiology. If I stay at Case, this is an exciting opportunity. There are other opportunities beyond Case that I'm also considering.

Q: Do you want to elaborate?

A: Not at present. You never know. But I'm very proud of what we've done in physics and I'm committed to continue helping that, and continuing to lead the effort in cosmology we've built into a nationally ranked group. There are demands and I have to decide where my talents best fit. I think being chair of the physics department wasn't the place right now.

Q: Do you wish you had more time for research?

A: Of course I do. But you have to balance what you do. Sometimes I wonder what's the most useful thing I do and where I'm most effective. Partly, stepping out of the chair position was to do that, although taking this medical school position is another hat. Stepping out of the chair position has removed an amazing time sink. Building the department is exciting ... but trying to stem off disasters and catastrophes and budget problems takes more time and they're less gratifying. So I did think stepping down would give me more time for research.

Q: One of the things that's helped you as a popularizer of science is the credibility you gained by being a researcher.

A: Yes. That's why I continue to do science, because I kind of feel like a fraud if I'm not. I get depressed if I'm not. I can't imagine for the near future I'll stop doing that, just for my personal well-being as well as my credibility. I like to think the body of work I've done continues to give me credibility to be a spokesman for science, but I also feel if I'm talking about science and not doing, I'm a fraud.

© 2005 The Plain Dealer. Used with permission.