Alicia Sometimes Interviews Sean Carroll

Alicia Sometimes is a contributor to Science Book a Day and recently completed an interview which she has kindly shared with us.

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I spoke to Sean Carroll about his book The Big Picture: On the Origins of Life, Meaning, and the Universe Itself. The book not only delves into astrophysics, it looks deeply into the universe through the lens of maths, history, biology, chemistry, philosophy, theology and a passion for understanding how everything melds together. Carroll asks the pressing questions of course. He weaves compelling narratives, scientific questions, many answers and explains scientific theories in relatable ways. Carroll writes, ‘What is the world really? It is a quantum wave function. At least until a better theory comes along.’ This sentence on its own is just a teaser out of context, you’ll have to read the whole book to see how he stitches the big picture together. This is a captivating book and Carroll is an absorbing writer.

Sean Carroll is a theoretical physicist, specializing in quantum mechanics, gravitation, cosmology, statistical mechanics, and foundations of physics and author. His books include, The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World, From Eternity To Here: The Quest for the Ultimate Theory of Time, Spacetime and Geometry: An Introduction to General Relativity and his latest book is The Big Picture: On the Origins of Life, Meaning, and the Universe Itself.

In your book, The Big Picture, you say the point of the book is not to stride confidently into multiple ongoing debates and proclaim ‘I have it all figured out’, quite the opposite. It is such a large array of things to talk about, how do you condense the meaning of the universe into one book?

Well, that’s the right question to ask. The short answer is I don’t offer the meaning, the answer to the meaning of life, to where the universe came from, to how life itself began or anything like that. I talk about how we can discuss these questions within a certain framework. So, there aren’t really that many answers in the book. It’s really laying out a set of pre-conditions for how we should talk about this and of course, even at that level we’re skipping a lot of the details. Mostly the book has been positively reviewed but one of the things that people can find frustrating about it, is that there’s a whole bunch more I could’ve talked about it but I did put it in the book.

How could you do that? How could you possibly? You’d have a voluminous amount of books wouldn’t you?

Well except that everyone wants you to put their thing, their interests in the book. They don’t want me to put everything in it. They just want to know why their particular pet topic is not in there. Everyone has to be pick and choose in some way.

Perhaps, in a short answer, what does it mean ‘The laws of physics underlying everyday life are completely known.’

This is an important fact about modern physics that we don’t actually advertise as much as we should but every word in that sentence: ‘The laws of physics underlying everyday life are completely known’ every word matters in that and a lot of people again like to disagree with that sentence by ignoring some of the words. So the word underlying is very, very important. It’s obvious that we don’t understand the laws of physics in large macroscopic configurations of stuff. We don’t know the laws of physics that apply to superconductors for example, high temperature super conductivity, much less higher level things like chemistry or biology or economics. But all of these things: super conductors, chemistry, biology economics, they’re all made of atoms and particles. And so the claim is that we know what the force is and the matter particles are that make up human beings and super conductors and so forth. And we know the laws that govern them and that’s a crucially important, huge fact about life. It does not say that we understand everything about physics. It does not say that physics is almost over. It’s not one of these famously embarrassingly wrong statements that in a few years we will have everything figured out. I have no idea when or if we’ll have everything figured out but the things we have figured out are a large enough domain to include everything happening in your and my bodies and in the rooms we’re sitting in right now.

Following on from that there’s always talk of a new particle, a new Higgs so to speak, why doesn’t a discovery like that, change the face of physics?

Oh, it would but it would not change our everyday life. That’s the important thing. It would not change the way in which physics impacts your everyday life. So dark matter, for example, is a very classic and likely very real particle that we haven’t discovered yet. Most of the matter in the universe is dark matter not ordinary matter and we haven’t seen the particle yet. So, what happens when we do discover it? Will that give us new insight into human biology or psychology or high temperature superconductivity? The answer is no. We know that it won’t. And the reason we know it won’t is because if it did, if some new particle or new force or whatever interacted with the ordinary particles, the atoms that you and I are made of strongly enough to be important then we would have found it by now. We know exactly how such particles could have prevented from being discovered yet, namely either they’re to be made or they just don’t bump into us very much or they decay away too quickly and in all of those cases it’s not going to affect how you and I go through our lives.

So when we go on a date the Higgs boson won’t really matter?

It really doesn’t. The Higgs is exactly a marginal case because the Higgs boson doesn’t matter, you need to build a ten-billion-dollar particle accelerator to make one and then it decays away within a zepto-second so there’s not a lot of Higgs bosons flying around inside your body. On the other hand, the Higgs boson is special because there is the Higgs field which is pervading all of space and that kind of does matter in the sense that it gives mass to the electrons and to the quarks that are in your body. I’m going to count that but I’m being generous, we could argue over it but I’ll count that as not affecting our everyday lives. We discovered the Higgs boson in 2012 so now we have a theory that is really not going to be changed in terms of how it impacts our everyday lives. It might be changed in the sense that we discover a whole new way of thinking about space-time in the universe but still even within that theory there will be a way of talking that makes perfect sense, which is: electrons and protons and neutrons interacting through electromagnetism and gravity.

You talk about how quantum mechanics is so vastly misunderstood by non-physicists and say this is unfortunate because where misunderstanding dwells misuse will not be far behind and no theory in the history of science has ever been so misused and abused. Why do you think that is?

Well I think there’s two things going on, it’s a great question, it’s a question for a book in and of itself but one of the reasons why it is, is because quantum mechanics is hard and therefore physicists don’t understand it. It’s not just that the general public doesn’t understand it, it’s that because quantum concepts are so different and so unfamiliar even though quantum mechanics was put together in the 1920s we professional physicists still don’t agree on what it is and what it means so of course other people are going to disagree and misuse it. That’s one reason. The other reason is that the words we use to describe what quantum mechanics does say are ripe for misinterpretation. We use words like ‘the measurement of a system by observing it affects its nature or, ‘there is no way to predict what will happen in the future’ or ‘two different particles can be millions of miles away and yet entangled with each other’. All of these are statements that very specific technical meanings to a physicist but have wildly different meanings to person who hears those vocabulary words without knowing the underlying math.

It [quantum mechanics] can be poetic in its analogy, you just mentioned some sentences there which I have read a little about the science and understand a bit, but of course it’s quite poetic so people may confuse entanglement with two people across the room knowing exactly what each other is thinking and so forth, so how important is language to the communication of science?

It’s very important and it’s a problem we will always be stuck with because when physicists or mathematicians come up with a whole new idea, a new kind of thing that has never been thought of before, we almost never invent a new word for it. We borrow a word that was invented long ago like ‘entanglement’ or ‘observation’ or so forth. Those old words come with connotations, come with ideas and definitions that are not going to be appropriate for this new definition we have in mind so it’s a constant struggle because you want to be able to describe the discoveries of physics and terminology that everyone can understand. You use analogies you use words that already exist but then you’re going to run the danger that people will take you too seriously or too literally and over interpret what it is you’re saying.

For instance, dark matter and dark energy, two very different things but they use the word ‘dark’…

Yes, that’s right and dark energy especially uses the word ‘energy’ which is just asking for trouble. A lot of people want to know, does the dark energy give us any hope for solving the energy crisis or is dark energy going to help us teleport to new dimensions and so forth. They’re very different from each other: dark matter dark energy. Dark matter is probably, we think, very much like ordinary matter it’s just a new kind of particle that we haven’t discovered yet and it doesn’t interact very much, only through gravity do we only notice its effects, whereas dark energy isn’t even a particle, it something that is spread all throughout space and has a constant density of energy and therefore pushes the universe apart. We see the effects of this dark stuff but it’s two very different kinds of dark stuff and we haven’t really put our finger on what it is exactly yet.

One of the most interesting things in the book for me was talking about low to high entropy and you illustrate this your experiment or talk about coffee with milk, maybe tell us a little bit about low to high entropy and the universe, in you know, a minute or so…

Sure, no problem. I think it’s really one of those foundational facts about the universe is that the past is different from the future, what we call the arrow of time. And to physicists we know why that is true, it’s because entropy is increasing. Entropy is a measure of the disordliness of the universe. When the universe started out 13.8 billion years ago it was very orderly, low entropy and it is becoming more and more disorderly and high entropy ever since. That’s a well-established story, I wrote a whole other book about that, what I really want to emphasise in this book was that overall evolution towards disorder is not incompatible with the appearance of very complex structures like you and me. In fact, it’s the opposite. When entropy increases from very low to very high that’s precisely when complex structures can form. So we shouldn’t be surprised that very complicated, intricate things like you and me and other people on earth rose in the natural, undetermined non-teleological progression of the evolution of the universe according to the laws of physics.

Being a scientist, you’re full of facts and exploring theories, how does the philosophy fit in with your life?

Well, part of it is that I like it, part of it is that I’m not necessarily trying to fit it in with my life. In fact, when I was an undergraduate philosophy minor most of my philosophy courses were in moral and ethical and political philosophy not in philosophy of science at all. Most scientists get along perfectly well without knowing or caring anything about philosophy and I think that is as it should be, it’s a different field. But certain kinds of scientific questions do benefit from careful philosophical analysis and those just happen to be the questions I care about the most. You know, where did the universe come from, what is the nature of space and time and so forth. So I personally have benefited enormously from talking to philosophers about how these ideas succeed and fail and logically fit together and where the holes in our current theories really are.

What will we know in the next fifty years?

For me personally it’s more about the journey than the destination so I’m having enormous fun thinking about the world trying to understand it a little bit better and better piece by piece. Of course I would love to come up with a wonderfully effective and true theory that no-one has thought of before, that really helped us understand, for example: how space-time emerges from quantum mechanics. This is the research topic that I’m most heavily focused on right now and if I don’t do it—the odds are against me or any one other individual person doing it— but I do hope that over the next few years we really can make great strides in understanding this is very long-term quest for quantum gravity

I think that part of it is that we haven’t really taken the quantum mechanics side of things seriously. This is where the philosophy comes into it. We don’t understand what quantum mechanics is and surprisingly we don’t understand quantum gravity, well maybe that shouldn’t be a surprise at all. Maybe trying to understand the foundations of quantum mechanics turns out to be really important to understanding quantum gravity.

And you talk about when you were a kid you used to stay up at night and think about the universe, I think a lot of us have. Is there anything that keeps you up at night scientific wise?

Well, I still don’t know whether the universe had a beginning. That is very frustrating to me. I think there’s certain things— that on the basis of general principles we can say, well one idea is more likely than the other—but here’s one I’m just extraordinarily open-minded about. I don’t even have a preference. I used to think strongly that the universe did have a beginning. The Big Bang says that that’s what’s true, but then, thinking about it more and thinking about how quantum mechanics fit into it, I started to think pretty firmly that the universe did not have a beginning, that it was eternal, that it went on forever. And now I’ve gone back and realised there’s ways that the universe could have had a beginning even with quantum mechanics and now I just don’t know. That’s very frustrating and annoying. That’s something that really matters a lot, how we view what the universe is.

If you have no idea there’s no hope for the rest of us. Thank you so much for talking with me.

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Alicia Sometimes is a writer, poet and broadcaster. She is a regular guest on ABC 774 and Radio National talking books, film and culture. Alicia was a 2014 Fellow at the State Library of Victoria and writer and director of the science-poetry show, Elemental that toured extensively in planetariums around the world. She is passionate about arts and science and is currently working on a new show on particle physics.