"Lost in Math" - Sabine Hossenfelder

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Sabine Hossenfelder is a quantum gravity phenomenologist - she links theories to experiments and observations - and she has a popular blog, Backreaction. She is also losing her faith in physics as it is presently conducted.

Here is the problem. The two great foundations of physics, quantum theory and relativity, are completely successful to the precision of existing experiments and observations. Yet they are mutually inconsistent. Attempts at unification (there are many, including string theory) are presently untestable, their verification beyond the limits of colliders and instruments. There are other conundrums too such as the nature of dark energy and dark matter. In the absence of experimental data, ungrounded theories abound - they are cheap, after all! - driven by aesthetics and groupthink.

Hossenfelder is not a superstar physics-populist with a major TV contract and a slew of pop-sci publications. 'Lost in Math' is not intended for that market. It's an extended meditation on the consequences of the absence of meaningful experimental feedback. The author interviews the world's leading physicists (Witten excepted) and is typically unimpressed by what she hears. Her reactions are ironic, sardonic and hilarious. Her text reports back as if talking to peers. How refreshing.

As a bonus you get an insider's view of the hot issues: what's really happening at the LHC, the role of dark matter in cosmology and the evolution of the universe .. as well as the failure of all attempts to characterise it, the problems with the flavours of multiverse, the measurement problem, the black hole firewall controversy.

There's no easy solution to the great stagnation in fundamental physics. The author is keen that the community should be more aware of its cognitive biases, its herd behaviour and groupthink but it seems difficult to identity the incentive to improve.

As for Sabine Hossenfelder herself, she may believe that publication of this book has killed any chance of tenure for ever, but probably it hasn't. One niche closes, another opens.

I had my doubts about buying this book. Would I really learn anything that I hadn't already picked up from many other popular science books and innumerable blog posts? And is the fragility of  beauty, naturalness and elegance as criteria for theory acceptability really enough to sustain a whole volume? Yet Hossenfelder's work is wider and more profound than that. Her tour of the state of the art is a joy to read, discerning and intelligent insights sprinkled throughout. I was engrossed from beginning to end.