Skip to main content

Lost in Math - Sabine Hossenfelder *****

One of my favourite illustrations from a science title was in Fred Hoyle's book on his quasi-steady state theory. It shows a large flock of geese all following each other, which he likened to the state of theoretical physics. In the very readable Lost in Math, physicist Sabine Hossenfelder exposes the way that in certain areas of physics, this is all too realistic a picture. (Hossenfelder gives Hoyle's cosmological theory short shrift, incidentally, though, to be fair, it wasn't given anywhere near as many opportunities to be patched up to match observations as the current version of big bang with inflation.)

Lost in Math is a very powerful analysis of what has gone wrong in the way that some aspects of physics are undertaken. Until the twentieth century, scientists made observations and experiments and theoreticians looked for theories which explained them, which could then be tested against further experiments and observations. Now, particularly in particle physics, it's more the case that physicists dream up whole rafts of theory supported only by mathematics, much of which can never be experimentally confirmed, and what can be checked is often so expensive to work on that only a very small number of possibilities can be examined. 

It's the maths (if we're talking beauty, I have to confess I find 'math' a very ugly word) that is in the driving seat, which surely is wrong. As Hossenfelder points out, string theory works best if the cosmological constant value that reflects the expansion or contraction of the universe is negative. Unfortunately it's actually positive, but most string theorists spend their time working with a negative cosmological constant. It can make for beautiful mathematics - but has nothing to do with our universe.

It's also the case that the vast majority of theoretical advances in physics were made by individuals, where now most theoreticians work in teams - it's tempting to wonder, if a camel is a horse designed by committee, what is a theory developed by group consensus?

Hossenfelder repeatedly comes back to two measures used to test theories - beauty, which is inevitably a subjective phenomenon, even though there is some agreement of what is required for beauty - and naturalness, which appears more scientific as it involves numbers, but relies on a bizarre confidence that values in nature that are dimensionless (for example ratios of masses) should be Goldilocks-like in not being too big or two small, but should be around the value of 1. The physicists she speaks to through the book (nearly all male), often seem to cling onto these measures without being able to justify them, other than saying that everyone else likes them too. There are some attempts - one suggests the appeal to beauty is an evolutionary response to a successful theory, but that only shows a weak understanding of evolution (though evolutionary developments can, at least, probably explain the physicists' love of symmetry - and it's not because nature has to be that way, but because we find symmetrical faces attractive).

Vast amounts of physicist-hours are being put into theories such as string theory, which seems pretty much incapable of doing the main job it is supposed to (though does have some side benefits), or defending the extension of the standard model of particle physics called supersymmetry, even as more and more evidence suggests it is unlikely to be true. Hossenfelder shows that clinging to theories past their sell-by date is almost inevitable because physicists are people too. If you've spent half your career on a theory, you don't give it up easily, even though scientists are supposed to love falsification. And if hundreds of other people (remember the geese) are working on a particular theory, surely it must have some substance behind it? One thing the book doesn't mention, but may be worth thinking about, is perhaps there are too many theoretical physicists? Hossenfelder points out in a period of about a year when the LHC produced data that looked interesting but turned out to be a statistical fluctuation, 500 papers were published exploring this non-event theoretically, many published in top journals.

Relatively briefly, Hossenfelder also examines the aspects of modern academic scientific life that make it hard to give the amount of time to actually working on theory that should be the case, citing estimates of around 40% going to actual work (another 40% going to grant applications). The processes required to get funding also tend to work against original thinking and deviating from the goose flock - there seems little doubt that this structure makes a large negative contribution to the whole business, though no one seems to have an answer to the problem.

The only negative I have with the book is that Hossenfelder, like many practising physicists, struggles to explain some of the actual physics in a way that conveys any meaning to the general reader. Luckily, this is not essential here - this is not a book to learn about physics, but about the way modern physicists work. Interestingly, Hossenfelder complains that 'popular science books about special relativity are often full of rocket ships and satellites passing each other. But all of this is unnecessary decoration. Special relativity follows from the three symmetries [she lists] above, without twins in spaceships and laser clocks and all that.' While this is true, the way symmetries are used here is an argument that is near-impossible to follow for a non-mathematician. The twins paradox and light clocks make it much easier for the rest of us to get a grip on the subject (and, to be fair, my undergraduate special relativity textbook makes use of both, so it's not just popular science doing  it).

Inevitably there will be a widespread negative reaction from the physics community (which has already started) - but this is not surprising when Hossenfelder is attempting to burst a self-reinforcing social bubble just as powerful as those that surround American political parties. The knee-jerk reaction is always to deny there's anything wrong - yet here it seems so obviously a case of the emperor's new clothes. 

Some readers may take this book to be an anti-science one - but it really isn't. Hossenfelder is merely pointing out a deep problem in some parts of physics, but she in no way undermines the remarkable scientific discoveries that have come from centuries of physics (and applications we benefit from as a result of some of them). Rather, she is saying that people in her profession need to step back from the coalface and take stock of what they are really doing and whether this particular approach really makes sense. True creativity often requires this - but most of us find it difficult to do. And it's about time a physicist said this.

Highly recommended (and very brave).


Hardback:  
Using these links earns us commission at no cost to you


Review by Brian Clegg

Comments

Popular posts from this blog

Four Way Interview - Jim Al-Khalili

Photo by Nick Smith Jim Al-Khalili hosts The Life Scientific on BBC Radio 4 and has presented numerous BBC television documentaries. He is Professor of Theoretical Physics and Chair in the Public Engagement in Science at the University of Surrey, a New York Times bestselling author, and a fellow of the Royal Society. He is the author of numerous books, including Quantum: A Guide for the Perplexed; The House of Wisdom: How Arabic Science Saved Ancient Knowledge and Gave Us the Renaissance; Life on the Edge: The Coming of Age of Quantum Biology; and The World According to Physics. His latest book is The Joy of Science . Why joy?  While I focus more in the book on the process of science itself to gain knowledge about the world, I also wanted to get across the fact that science is so much more than hard facts and lessons in critical thinking.  Science helps us see the world more deeply, enriches us, enlightens us.  The closer we look, the more we can see and the more we can wonder. I feel

Transformer - Nick Lane *****

This is probably the best book on biology (and more specifically biochemistry) that I've ever read. Ever since Richard Dawkins wrote The Selfish Gene , we've been dazzled by the importance of the genetic code (or, as Lane points out in one of his many asides, what should really be called the genetic cipher) - but this focus has tended to give an exaggerated importance to the information stored there. Of course it's essential to life - but as this book explores, chemistry and energy are what life is really about. Nick Lane points out that there is no difference in the information in an organism just before and just after it dies - but there's quite a lot of difference in terms of its life. Biology and chemistry can both be extremely difficult to put across in popular science. Biology because it's so complicated with vast numbers of molecules and processes involved, and chemistry because, dare I say it, it can appear a bit dull. What Lane does wonderfully well is to

Wonderdog - Jules Howard *****

As Jules Howard acknowledges, there have been plenty of books about what makes a dog tick, whether they are training manuals, evolutionary examinations such as The Wolf Within or ethological studies of humans' closest animal partner such as If Dogs Could Talk . But most of Jules Howard's Wonderdog takes us into the roles that dogs have played in advancing science. Some of this material is fairly gruesome. We discover, for example, dogs' importance to medical research, particularly at a time when experimenting on animals had few ethical limits. What makes the book enjoyable is the way the Howard ties in his history with engaging stories - such as the brown dog statue, put up in Battersea in 1907 as a memorial to a dog horribly misused by vivisectionists, only for the statue to be destroyed by the council to bring an end to frequent attacks by infuriated medical students. (The statue has since been replaced.) Similarly, dogs have proved valuable in widening our understandin