Universal Education: Physics for Everyone
An interview with Sean Carroll
“In physics and the mathematical sciences, the separation between everyday and professional knowledge is bigger than in other fields… there’s a huge barrier in physics that doesn’t need to be there.”
Science for the masses: an honourable ambition for a cosmologist, theoretical physicist, philosopher and bestselling author.
Sean Carroll has received an impressive array of prizes and fellowships from the likes of NASA, the American Institute of Physics, the Royal Society of London and the Guggenheim Foundation. His TED Talk, ‘Distant time and the hint of a multiverse’, has over 1.8 million views. He also hosts Mindscape, a podcast about science, society, philosophy, culture and the arts.
Sean has written several award-winning popular science books. This interview will focus on his latest title, The Biggest Ideas in the Universe: Space, Time and Motion, which was published in September 2022.
Physics is a complex and wide-ranging subject. What particular aspects of space and time do you explore in your new book?
This book is about what we call classical physics — the descendant of Isaac Newton and Albert Einstein’s theories. In the book, I talk about the general concepts of physics; forces, energy and how things move around; space and time — both separately and together, in the form of curved spacetime and general relativity; then I finish up with black holes.
That sounds pretty complicated! Some of the theories underpinning classical and quantum physics are hundreds of years old. How do you convey fresh ideas and make them relatable to a 21st-century audience?
To be perfectly honest, the ideas in this book are not really fresh. I wanted to explore the most established ideas that will still be taught to students 1000 years from now. The fact that an idea originated a long time ago is not really the point. My intention was to explain it in a way that fills the gap between a typical popular science discussion — using metaphors and analogies — and a textbook that suggests you need to study for years to learn all the details.
The Biggest Ideas in the Universe sits between the two; it offers more than a typical textbook, including key equations, but we assume that readers start with no mathematical background. It’s a book for everybody. We don’t deal with problem sets and all the stuff that physics students have to worry about. We’re just giving you the good stuff, heading straight to the ideas that formed the foundation of how we think about the universe.
The blurb of the U.S. edition claims that you can transform ‘equations that often look like gobbledygook’ into ‘meaningful poems’. That’s quite a talent! Do you think there’s something creative about translating complex scientific concepts into accessible ideas?
I think there is, because physicists take courses for years to learn a particular way of thinking about these concepts. It can be hard to remember what it was like before you understood all the equations. I can’t really say whether I did a good job, but I tried to explain why we use each equation in a way that would make sense to everybody.
My crucial trick is to not expect readers to solve the equations. I’m not teaching them to become professional physicists, but I want them to understand what the equations mean so they can grasp concepts like space, time, general relativity and Newtonian mechanics.
As a popular science author, why do you think it’s important for non-scientists to have at least a basic understanding of how the universe works?
Well, it’s our universe; we all live here and have to deal with it in various ways. Recent years have certainly taught us that scientific literacy is very important. Again, I’m really concerned about the gap between the professionals — who have a precise, quantitative understanding — and the rest of the world. People deserve an introduction, so they can separate crazy claims from sensible ideas. The more you understand, the more you can appreciate what’s going on — whether it concerns vaccinations or general relativity.
I think metaphors are great. Explaining ideas in a way that enables people to access and fully appreciate them is important, but there will always be a subset of people who want a precise statement. The great news is that the equations in my book are no different from those used by professional physicists.
I get the sense that physics is regarded as elitist or too complicated for everyone to understand. Do you think that impression puts people off when they’re deciding what to study or pursue as a career?
I don’t think it’s elitism so much as the hyper-specialisation of knowledge in the modern world; we know so much about so many different things that nobody can be an expert on several things at once. At best, we have a somewhat superficial knowledge of many things and a deeper knowledge of just a few fields.
In physics and the mathematical sciences, the separation between everyday and professional knowledge is bigger than in other fields. Even an amateur can have a pretty good understanding of economics, history or literature, but there’s a huge barrier in physics that doesn’t need to be there. We’re working to overcome it.
That’s an impressive goal. I’m intrigued by your journey into physics. History is full of noteworthy scientists, including those you mentioned earlier. Is there anyone in particular who stands out as an idol for you?
To be honest, I’m against the idea of having idols. There have been many physicists whose work I admire enormously, but it would be a mistake to convey that admiration to someone I don’t know personally.
My book mentions scientists like Isaac Newton and Albert Einstein, as well as lesser-known people like Caroline of Ansbach, who later became Queen of Great Britain and Ireland. She played a crucial role in starting a dialogue between Gottfried Wilhelm Leibniz and Samuel Clarke (a supporter of Isaac Newton); Newton and Leibniz were the two inventors of calculus. An Irish mathematician and physicist called William Rowan Hamilton developed a whole new way of thinking about classical mechanics. Roy Kerr and Karl Schwarzschild discovered the solutions to Einstein’s equations, which gave us black holes.
There are so many people who played a role — either big or small — in the history of physics that we never hear about, so I tried to put a spotlight on them as well.
Too often, people are written out of history or overshadowed by bigger names. It’s important, for children especially, to be able to aspire to role models from different backgrounds. How did you get into physics and then become a popular science writer?
I fell in love with physics at a young age. I can’t tell you exactly why, but it was not due to scientists in my family or even the teachers at school. I just started reading books about black holes, the Big Bang, quarks and leptons when I was about 10 years old. I found them in the local public library and was absolutely enthralled. I don’t recommend that people decide their life course at age 10, but it’s worked out pretty well for me!
I really wanted to get into this stuff at the deepest level possible, so that I could contribute to human knowledge. But I was also interested in broader questions about the most esoteric, speculative areas of physics and philosophy. My work is not going to lead to a cure for cancer or a better iPhone. We study physics because we’re curious; it’s part of the human condition. So, I think it’s important to not only discover new things about the universe, but also to explain them in terms that people can understand.
Do you think there’s a link between writing and teaching in a university setting?
Yes, but different skills and techniques are required to teach graduate and undergraduate physicists, undergraduates who don’t study physics, high school students, and people who are not in formal education. Everyone comes from a different background and develops a variety of interests.
I remember a formative moment during a talk by Martin Rees, a famous theoretical astrophysicist and the UK’s Astronomer Royal. In the middle of the presentation, which was supposed to be about cosmology, he started talking about life on other planets. As a professional cosmologist, I thought, ‘That’s not what he should be talking about. That’s not cosmology at all!’ But the audience was really interested in what he was saying, and I realised that the most important questions aren’t necessarily the same for people in the audience and for professionals. Maybe we should give people what they want, while trying to convince them that the things physicists find interesting are also worth their attention.
That’s a fascinating insight. Can you offer 3 key takeaways from your book — if it’s even possible to distil the universe into 3 things?
Each chapter in The Biggest Ideas in the Universe covers one of the big ideas: time, matter, gravity, etc. There are so many good ideas in there.
Let’s be bold and say that one idea is calculus — the notoriously difficult part of math. Calculus is supposedly what separates the math that students can understand from the stuff that goes over their heads, but I don’t think that’s true. Calculus is just the mathematics of change: how fast things are changing and how much change there has been. In order to appreciate modern physics, it’s absolutely crucial to understand a bit of calculus.
The second idea would be spacetime. We talk about space and time separately, and then we glue them together to make spacetime. These ideas came from Einstein and his collaborators, but we’ve since realised that the four-dimensional spacetime in which we live is curved and dynamical — it has a life of its own. We understand that as the force of gravity and the expansion of the universe. Grasping why space and time are part of the same thing is an important insight to have.
Finally, at a more abstract level, we’ve got the concept of equations: formulating a scientific theory in terms of pristine sets of symbols that pack enormous power into concise notation. It’s very much like learning a foreign language. As I say at the beginning of the book, some of our equations use Greek letters, but they’re easier to understand than actually learning Greek (if you’re not a native speaker). We start slowly, with F = MA (Force equals Mass times Acceleration) and build up to Einstein’s equation in all its glory. Once you overcome the psychological barrier of unfamiliarity with the symbols, it becomes rather fun. It’s like deciphering a code; once you crack the puzzle, a whole new world opens up.
That puzzle metaphor really resonates with me because I studied physics and French at A Level, which both involve symbols. I didn’t take maths, so there were certain aspects of physics that I struggled with, but my language skills definitely helped.
The whole point of my book is that it’s designed for everybody. As with any book, some people will like it more than others, but there might be readers who don’t yet know that they’re the right audience. Once the door opens a bit and you realise that F = MA isn’t so hard, you discover a whole new way of using your brain to appreciate the universe. I’m privileged to be able to offer this to people who haven’t already experienced it.
In essence, you can spark the curiosity inherent in each of us by making science more accessible. This title is the first in a trilogy of The Biggest Ideas in the Universe. What will the following two books focus on?
I reveal it in the introduction, so I’m locked in! The first book focuses on classical physics, including relativity. The second book is about quantum physics. There’s a big payoff for taking this approach, because it’s not just the usual introduction to quantum mechanics, with Schrödinger’s cat and the double-slit experiment. Instead, we teach you quantum field theory, which is how modern physicists think about the world at the most advanced level. This involves the Standard Model of particle physics with Feynman diagrams and equations, presented in a way that allows everyone to understand them.
The third book will explore complexity and emergence. We finally admit that there are systems involving more than 2 or 3 particles at a time. Whether we’re talking about the whole universe, a box of gas or the population of a city, there are many different systems in which we see emergent higher-level behaviour due to interactions between all the tiny parts. We’re only just catching on to the importance of this area of physics, so it’s exciting to think about what we’ve learned so far and set the stage for future discoveries.
I didn’t want this collection of books to be overly speculative, so we don’t talk about the multiverse, extra dimensions or interpretations of quantum mechanics. However, there’s a lot we do understand that’s really solid. Even though Einstein came up with a better theory than Newton, we still teach Newton’s equations because they’re good enough to get a rocket to the moon and back. I try to teach ideas and theories that are not going to disappear, so you can hand these books down to your kids; future generations will still learn something fun about the universe.
As you say, it’s important to understand the history of scientific discovery in order to appreciate what we know today and be at the forefront of what we will learn in the future.
I love sprinkling in historical anecdotes because the stories behind these ideas are often quite wild. You don’t know ahead of time where science is going while you’re doing it. But, at the same time, we’re not hamstrung by history. I teach the key ideas in an order that I think makes sense, whether or not it’s chronological. When ideas are developed over time, we’re often very confused in the early stages; I tried to tidy that up by including only the most important and long-lasting concepts.
A collection of Sean’s books can be found on Perlego:
- From Eternity to Here: The Quest for the Ultimate Theory of Time (2011)
- The Particle at the End of the Universe: The Hunt For The Higgs And The Discovery Of A New World (2012)
- The Big Picture: On the Origins of Life, Meaning, and the Universe Itself (2016)
- God and Cosmology: William Lane Craig and Sean Carroll in Dialogue (2016, edited by Robert B. Stewart)
- Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime (2019)
- The Biggest Ideas in the Universe: Space, Time and Motion (2022)
