Review: Lost in Math, by Sabine Hossenfelder

[Russ Allbery]

Lost in Math
by Sabine Hossenfelder

Publisher: Basic
Copyright: June 2018
ISBN:      0-465-09426-0
Format:    Kindle
Pages:     248

Listening to experts argue can be one of the better ways to learn about
a new field. It does require some basic orientation and grounding or
can be confusing or, worse, wildly misleading, so some advance research
or Internet searches are warranted. But it provides some interesting
advantages over reading multiple popular introductions to a field.

First, experts arguing with each other are more precise about their
points of agreement and disagreement because they're trying to persuade
someone who is well-informed. The points of agreement are often more
informative than the points of disagreement, since they can provide a
feel for what is uncontroversial among experts in the field.

Second, internal arguments tend to be less starry-eyed. One of the
purposes of popularizations of a field is to get the reader excited
about it, and that can be fun to read. But to generate that excitement,
the author has a tendency to smooth over disagreements and play up
exciting but unproven ideas. Expert disagreements pull the cover off of
the uncertainty and highlight the boundaries of what we know and how we
know it.

Lost in Math (subtitled How Beauty Leads Physics Astray) is not quite
an argument between experts. That's hard to find in book form; most of
the arguments in the scientific world happen in academic papers, and I
rarely have the energy or attention span to read those. But it comes
close. Hossenfelder is questioning the foundations of modern particle
physics for the general public, but also for her fellow scientists.

High-energy particle physics is facing a tricky challenge. We have a
solid theory (the standard model) which explains nearly everything that
we have currently observed. The remaining gaps are primarily at very
large scales (dark matter and dark energy) or near phenomena that are
extremely difficult to study (black holes). For everything else, the
standard model predicts our subatomic world to an exceptionally high
degree of accuracy. But physicists don't like the theory. The details
of why are much of the topic of this book, but the short version is
that the theory does not seem either elegant or beautiful. It relies on
a large number of measured constants that seem to have no underlying
explanation, which is contrary to a core aesthetic principle that
physicists use to judge new theories.

Accompanying this problem is another: New experiments in particle
physics that may be able to confirm or disprove alternate theories that
go beyond the standard model are exceptionally expensive. All of the
easy experiments have been done. Building equipment that can probe
beyond the standard model is incredibly expensive, and thus only a few
of those experiments have been done. This leads to two issues: Particle
physics has an overgrowth of theories (such as string theory) that are
largely untethered from experiments and are not being tested and
validated or disproved, and spending on new experiments is guided
primarily by a sense of scientific aesthetics that may simply be
incorrect.

Enter Lost in Math. Hossenfelder's book picks up a thread of skepticism
about string theory (and, in Hossenfelder's case, supersymmetry as
well) that I previously read in Lee Smolin's The Trouble with Physics.
But while Smolin's critique was primarily within the standard aesthetic
and epistemological framework of particle physics, Hossenfelder is
questioning that framework directly.

Why should nature be beautiful? Why should constants be small? What if
the universe does have a large number of free constants? And is the
dislike of an extremely reliable theory on aesthetic grounds a good
basis for guiding which experiments we fund?

  Do you recall the temple of science, in which the foundations of
  physics are the bottommost level, and we try to break through to
  deeper understanding? As I've come to the end of my travels, I worry
  that the cracks we're seeing in the floor aren't really cracks at
  all but merely intricate patterns. We're digging in the wrong
  places.

Lost in Math will teach you a bit less about physics than Smolin's
book, although there is some of that here. Smolin's book was about
two-thirds physics and one-third sociology of science. Lost in Math is
about two-thirds sociology and one-third physics. But that sociology is
engrossing. It's obvious in retrospect, but I hadn't thought before
about the practical effects of running out of unexplained data on a
theoretical field, or about the transition from more data than we can
explain to having to spend billions of dollars to acquire new data. And
Hossenfelder takes direct aim at the human tendency to find
aesthetically appealing patterns and unified explanations, and scores
some palpable hits.

  I went into physics because I don't understand human behavior. I
  went into physics because math tells it 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.

  "We cannot give exact mathematical rules that define if a theory is
  attractive or not," says Gian Francesco Giudice. "However, it is
  surprising how the beauty and elegance of a theory are universally
  recognized by people from different cultures. When I tell you,
  'Look, I have a new paper and my theory is beautiful,' I don't have
  to tell you the details of my theory; you will get why I'm excited.
  Right?"

  I don't get it. That's why I am talking to him. Why should the laws
  of nature care what I find beautiful? Such a connection between me
  and the universe seems very mystical, very romantic, very not me.

  But then Gian doesn't think that nature cares what I find beautiful,
  but what he finds beautiful.

The structure of this book is half tour of how physics judges which
theories are worthy of investigation and half personal quest to decide
whether physics has lost contact with reality. Hossenfelder approaches
this second thread with multiple interviews of famous scientists in the
field. She probes at their bases for preferring one theory over
another, at how objective those preferences can or should be, and what
it means for physics if they're wrong (as increasingly appears to be
the case for supersymmetry). In so doing, she humanizes theory
development in a way that I found fascinating.

The drawback to reading about ongoing arguments is the lack of a
conclusion. Lost in Math, unsurprisingly, does not provide an epiphany
about the future direction of high-energy particle physics. Its
conclusion, to the extent that it has one, is a plea to find a way to
put particle physics back on firmer experimental footing and to avoid
cognitive biases in theory development. Given the cost of experiments
and the nature of humans, this is challenging. But I enjoyed reading
this questioning, contrarian take, and I think it's valuable for
understanding the limits, biases, and distortions at the edge of new
theory development.

Rating: 7 out of 10

Reviewed: 2020-03-23

URL: https://www.eyrie.org/~eagle/reviews/books/0-465-09426-0.html

-- 
Russ Allbery (eagle at eyrie.org)             <https://www.eyrie.org/~eagle/>