Lost in Math: How Beauty Leads Physics Astray

Sabine Hossenfelder is a physicist with a social media following, a much beloved blog, an attitude, and now a book to go along with it all. This is not a physics book, it is a philosophy book. Its subject matter falls squarely into "philosophy of science". It is not a book about philosophy of science, but a book that does philosophy of science. Specifically, She mounts a strong critique of present attitudes and assumptions underlying approaches to today's work in theoretical physics and cosmology. Particle physics, string theory, quantum gravity, quantum mechanics and field theory, black holes, and the origins of the universe all come within her scope. In Dr. Hossenfelder's view all of them suffer from a similar bias towards the idea that mathematical consistency alone is a truth criterion. Nowhere is this made more plain than in her delightful demonstration that the present predilections of every single one of the above fields can be turned into a multiverse hypothesis!

Hossenfelder knows that data is important. She also knows that modern experimentation in the physical and cosmological sciences is expensive and sometimes takes years to produce data and sometimes not even then. The physicists know this too. It used to be that theories explained existing data and then made new predictions subsequently confirmed or ruled out by further experiments. But the easy experiments have been done. The problem is that there are too many physicists, too many people chasing the next grant, the next tenured position, and not enough money, or new data, to go around. This is a part of the problem, the economics, sociology, and politics of the field. She addresses these, but they are a secondary concern. Her primary concern is squarely philosophical.

At the present level of exploration of physical foundations there are darned few predictions to be confirmed or denied either because doing so is too expensive, experiments have resulted negative outcomes, or the predicted phenomena lie beyond any conceivable experiment. What then are the legions of theoreticians to do? Noticing that many of the successful physical theories of the past have a certain elegance and simplicity about them, intrepid physicists turn to beauty and the notion of naturalness. Neither of these ideas is bad, but they are not, by themselves, good arbiters of truth and this is exactly Dr. Hossenfelder's point and the primary subject of the book.

Of the twin notions, naturalness is the easier to quantify as it comes down to there being no, or few, "arbitrary numbers" needed to make the theory match the data. The number "1" (or numbers very close to it) is "natural" because it doesn't change what it multiplies. Un-natural parameters (outside of science known as "fudge factors") detract from a theory unless they can be satisfactorily explained. The demand for explanation of the fudge factors drives further theory building and she notes that as one is explained, others seem inevitably to appear. Beauty is a more vague idea still as are associated ideas of simplicity (related to naturalness) and elegance. Beauty is, after all, in they eye of the beholder and this is no less characteristic of physicists and their foundational theories as it is in art.

Dr. Hossenfelder traveled from Stockholm to Hawaii and points in between interviewing famous physicists to garner their opinions on this subject. These interviews form a goodly part of the book. Some of her interviewees work firmly in the mainstream of modern physics. Others occupy peripheral positions but have enough street credit to be read by their peers, at least for a while. Her interviews are brilliant and funny. She asks good questions, philosophical questions, and all her interviewees agree with her! The present tendency in physics she so well illuminates is a problem! But there is also consternation. "What else can we do?" is an oft repeated refrain.

Through the process of relating all of this to us, Dr. Hossenfelder expresses her own insecurities about her choice of specialty, and even physics altogether! Has she wasted her time she wonders? Perhaps. But if I had the power I would hire this woman instantly; not in physics, but in philosophy! This theoretical physicist has a lot to contribute to the philosophy of science. Not that the physicists will care much of course. As is often the case in philosophy, insights go unrecognized until after problems that might have been avoided have fully broken upon us.

Dr. Hossenfelder is not absolutely alone crying in the wilderness here. There are a few of her peers in the physics community who see the same problems and have written about them; Lee Smolin comes immediately to mind and there are, perhaps, a few others. She should not despair however. Her credentials are impeccable. She has a lot more to contribute, if not to physics directly, then to philosophy of science. She should embrace her new community!

Sabine's easy writing style makes the reading a pleasure. She has serious issues with the direction the Particle Physics is headed and is not afraid to ruffle some feathers. She approaches the major stalwarts in that area and tries to get their viewpoints across. Her discussions make it obvious that the field is pushed forward and ruled more by wishful thinking rather than by unbiased evidence based approach. She tries to put forward some suggestions at the end for the way forward. Though she does not make it clear, she defines search for beauty as looking for symmetry, unification, and naturalness. On the whole the book reads like a farewell address to a field she loves.
Sabine's writing and communication abilities are top notch. Even someone who is not well versed in the field can enjoy reading the book. I highly recommend this to any scientifically curious person.

I have enjoyed reading Sabine's views on her blog before, and so I was not completely surprised by this book's premise nor its arguments. I was surprised by the interviews. This was different than I expected but quite enjoyable. Overall I found this hard to put down as Sabine's writing style and the interviews really kept me interested in the book's overall discussion.

As a quick summary, this is about theoretical physics focusing on particle physics, foundational physics, and some astrophysics. The problem is that there is a lack of new data and so the theorists are using principles other than observation to choose data. As Sabine makes clear this is not completely a new or bad problem, but in the past, new data was around the corner to help clear up which theoretical possibilities to chase. Without new observations, what principles should be used to come up with new things to research and explain? How do we justify them, and if we cannot, what should we do?

The book is written in an interview and comment style. I find that this really works well, as I find the comments helpful, interesting, and put the conversations in the appropriate context. I am also quite sympathetic to the arguments in the book. As a graduate student in physics (though not in the specialties this book focuses in), I think I see similar problems of popular arguments and a lack of really thinking about what problems should we be solving. I hasten to add that I do not think my fellow physicists are just wasting money and time, just that a lot of research does not appear to really be an important step when you think about how it actually contributes to the research program's overall goals. Perhaps I have become too much of a pessimist, but I fear that a lot of research is being done because it is the type of research that is done.

I find the different perspective Sabine offers compared to other general audience physics books to be refreshing and thought-provoking. It's certainly not an inspiring book, but I think it makes a strong point that we should stop and evaluate how we are thinking about research so that science can continue to provide us with relevant and exciting new knowledge.

If you're wondering where all those new theories come from,Hossenfelder's book is worth a read. Oh, and it's not a math book.
Excerpt from chapter 1:
"I went into physics because I don't understand human behavior. I went into physics because math tells how it is. I liked the cleanliness, the unambiguous machinery, the command math has over nature. Two decades later, what prevents me from understanding physics is that I still don't understand human behavior."