
Lost in Math - well_i_never
http://www.math.columbia.edu/~woit/wordpress/?p=10314
======
stupidcar
It seems like there may be a more general takeaway from what Hossenfelder is
saying, which is that fields that should be driven principally by empiricism
can be led astray by the development of a set of shared aesthetic preferences
that is used as a barometer of a theory or technique's attractiveness.

Such ideas of "beauty" may begin as a useful shorthand, in that they initially
incorporate experienced practitioners' intuition of what theories are more
reasonable, based on the history of their field and their collective
knowledge. But they are only useful for so long as they remain subordinate to
actual empirical evidence in the ultimate judgement of a theory or technique's
truthfulness.

But when the actual application of strong empiricism is difficult or expensive
(or becomes so, as has been the case in theoretical physics over the past
half-century), or just impossible, the aesthetic barometer can gradually
supplant evidence entirely. This may be the true measure of a science's
softness or hardness.

In the field of software engineering, there are concepts of "clean" and
"beautiful" code and languages. But how rigorously are such terms defined? How
closely does our subjective impression of a codebase's aesthetics mirror its
actual quality on those metrics that should matter most, such as its
performance, maintainability, quantity of defects, etc.?

~~~
sgt101
>In the field of software engineering, there are concepts of "clean" and
"beautiful" code and languages.

Anyone who has sat in a code review with two "true believer" "software
engineers" will know how subjective and poorly justified, yet fanatically
defended these positions are - in fact anyone recruiting will know how
damaging having a true believer in your team can be (two is a genuine
disaster).

Software isn't engineering because we can't measure anything much about it
apart from compression, speed and detected defects so far. Speed and
compression don't matter for 99% of modern software; we have laptops with 32Gb
memory, servers with 1/2 Tb and scores of Ghz cores - the need to write in C
has disappeared for _almost_ everyone. Detected defects is problematic because
as soon as you start counting them people stop submitting stuff to the code
repository until they have removed everything that they can find. That's a
problem because they hold onto it for weeks and meanwhile if it had been in
the repo everyone would have found twice as much. Also the team stop reporting
the stuff they have found and just talk about refactoring; also the team gets
less keen on testing..

So what do we measure ? We can't tolerance it; we can't deduce structural
properties; we can't deduce lifecycle (recycling, onward development)
properties. We don't know why the core engineering decisions got taken because
often the core decisions happen at 3:17 on Tuesday and no one even notices at
the time, or remembers later. It's not engineering, not close.

~~~
booleandilemma
I once watched the software architect at a company I worked for get called out
on why he was choosing a certain design decision that was going to impact a
critical component of the product, and he justified himself by saying he had a
good feeling about it. When pressed further he could only vaguely and
emphatically respond “I don’t know, I just think this is the best way”.

So this important decision was based on this dude (excuse me, software
architect) shrugging and saying it feels good.

~~~
platz
it could mean he's developed a sense in the "right side" of his brain which
isn't logic-based. Unfortunately, it's impossible to tell whether someone's
taste is bullshit or finely tuned. The best-in-class typically do not follow
axiomatic rules either. In this case it's probably the former.

~~~
sgt101
And it's great when someone like Johanna Weber has a brilliant insight about a
delta formed wing and it turns into a beautiful outcome like Concorde - if all
the calculations are around to un-bullshit it to bits !

------
fanzhang
What does this mean for the future of science and technology?

I find it fascinating that so much interesting physics has been discovered in
the last century -- for example I only recently found out the neutron
essentially a post WWI era discovery [1]. And yet so little fundamental
physics has come by in the last 30 years.

Now that there is no more increase in microstructure knowledge of the
universe, will the other sciences and then technology follow in this stoppage?

Arguably the Internet followed from computers which followed from transistors
which followed from fundamental physical theory of atoms and electrons from
less than 150 years ago.

Will the lack of new physics cascade down, or is there enough "stuff" between
physics and technology that tech can keep on going.

[1][https://en.wikipedia.org/wiki/Discovery_of_the_neutron](https://en.wikipedia.org/wiki/Discovery_of_the_neutron)

~~~
anonytrary
Modern advancements in physics over the past 100 years have opened a can of
worms. We still haven't even scratched the surface of quantum systems in
applications.

It wouldn't surprise me if the majority of physicists are now leaning towards
applications and less "fundamental" disciplines. Newton and Einstein were two
centuries apart! I think the past 100 years of physics will still run us
another century before we make any more groundbreaking advancements in theory.
It's not even as bleak as it sounds, because we're really at the tip of an
iceberg here already.

~~~
Koshkin
Well, today we have tools (and math) that are infinitely more powerful than
what we had a hundred years ago, while, in comparison, progress in fundamental
physics is now infinitesimally slow. That should tell you something.

------
owaty
Sabine Hossenfelder (the author of Lost in Math) recently appeared on the
Rationally Speaking podcast to talk about the book:
[http://rationallyspeakingpodcast.org/show/rs-211-sabine-
hoss...](http://rationallyspeakingpodcast.org/show/rs-211-sabine-hossenfelder-
on-the-case-against-beauty-in-phy.html)

------
danbruc
I am not a physicist, but I think while trying to complete our understanding
of matter and forces is certainly an important topic, it would be much more
important to finally understand quantum mechanics. Not that those are
independent topics but I don't think progress on quantum mechanics is
dependent on progress in high energy particle physics. Maybe energy scales at
which gravity becomes strong might be really interesting to understand how
space and time and particles fit together, but those are out of reach for the
foreseeable future.

~~~
FreeFull
I'm not a physicist either. From what I understand, the parts of quantum
mechanics that aren't still fully understood are where it overlaps with
relativity. Reconciling the two is still one of the big open problems, and
high energy particle physics does help in testing theories.

~~~
codethief
Physicist here.

> From what I understand, the parts of quantum mechanics that aren't still
> fully understood are where it overlaps with relativity.

Yes and no. You're right, one big question are high-energy completions of the
quantum field theories that make up the standard model and which we expect to
break down at very high energies. On the one hand, this expectation is due to
the fact that general relativity is likely going to play a role at these
scales, so we'll probably have to solve the puzzle of quantum gravity along
the way. On the other hand, though, there are many more reasons why the
quantum field theories we have right now are expected not to be the full
story:

1) For reasons of, well, beauty. Right now, the standard model has many free
parameters but even if you ignore the parameters for a second, it's also a
somewhat random collection of specific gauge theories (the latter is basically
another word for quantum field theory), i.e. specific gauge groups. Therefore,
people hope that there is an underlying "grand unifying theory" (GUT) that
should become visible at high energies. Note that the beauty that comes with a
GUT is only in parts what Hossenfelder means when she discusses "beauty".

2) More importantly than 1), the usual interpretation of the renormalization
procedure in QFT these days is that it is a way to exclude physics at the very
high energy scales from our calculations/predictions. Put differently, without
introducing a renormalization scale (basically a "maximum energy") the
equations we have blow up and people take this as a sign that our theories are
incorrect at extremely high energies. So in this sense, current quantum field
theories are nowadays seen as effective theories (which are only valid at low-
energy scales) of an underlying "complete" theory which will hopefully cover
all energy (and thus length) scales.

But apart from the lacking high-energy completion, there are more reasons to
believe that we don't fully understand nature yet and that we might need to
come up with a new theory:

3) Even after decades of research we're still lacking a rigorous mathematical
underpinning for practically all relevant QFTs. Considering that nature so far
has always been governed by laws that we could express in precise mathematical
terms, this might suggest that we're doing something wrong at a very
fundamental level. A lot of people (or at least those I have spoken to) hope
that a theory of quantum gravity will solve this (and thereby reestablish
mathematical sanity in high-energy physics).

4) Dark matter: As you might now, dark matter is a general name for the
apparent stuff that causes our observations to differ slightly from the laws
of gravity that we know (i.e. from general relativity). The existence of dark
matter doesn't necessarily mean that we'll need an entirely new theory but if
we're right in our assumption that dark matter consists of particle
excitations of another quantum field (usually called WIMPs), we'll need to at
least extend the current standard model.

5) The foundations of quantum mechanics: More specifically, the measurement
problem together with the issue of having different interpretations of QM and,
possibly, the issue of time. These are basically the issues danbruc meantioned
above. For some background info see for instance Steven Weinberg's lecture on
"What's the matter with quantum mechanics?" (discussed by Sabine Hossenfelder
here: [http://backreaction.blogspot.com/2016/11/steven-weinberg-
doe...](http://backreaction.blogspot.com/2016/11/steven-weinberg-doesnt-like-
quantum.html?m=1)) and Carlo Rovelli's recent book
([https://news.ycombinator.com/item?id=17376437](https://news.ycombinator.com/item?id=17376437)).
Again, some people hope that these issues, too, will eventually be solved by a
theory of quantum gravity but this is anything but clear. (By the way, a
friend of mine working on Bohmian Mechanics recently told me that there might
be experiments to distinguish Bohm's interpretation from the Copenhagen one,
so we might not even need to wait for quantum gravity.)

Anyway, let's assume for a second that we really need a full quantum theory of
gravity to solve all these issues. Then, what's our best shot at coming up
with a theory of quantum gravity? Well, studying the high-energy behavior of
particles and hoping to discover "new physics". So in this sense, you were
absolutely right of course. I just wanted to point out that it's not
reconciling relativity and quantum mechanics alone that drives us.

~~~
gfodor
(Non-physicist, please bear with me)

Of these 5 criticisms of contemporary theory, all of them except dark matter
seem to stem from a suspicion about the eventual result through the lens of
beauty, unification, etc. However, the dark matter problem stands out as one
where measurements do not line up with theory, and seems more of a classic
example of how we've typically "turned the crank" on making progress in the
past.

How big is the concerted effort to understand dark matter vs trying to attack
these other concerns in theoretical physics? It certainly seems like an
aggressive, field-wide effort is warranted given it's one of the few
universally acknowledged and reproducible blatant predictive errors in current
models. The discovery of these errors seems like a huge gift to physicists.

~~~
danbruc
_Of these 5 criticisms of contemporary theory, all of them except dark matter
seem to stem from a suspicion about the eventual result through the lens of
beauty, unification, etc._

I don't think it is really justified to label it this way. We know that
quantum field theory is not the correct final theory because it breaks down at
short lengths and high energies. It is in some sense most likely even the
completely wrong way for looking at the problem. Quantum field theories are
mathematical tools to deal with many particle systems and they have some nice
properties like making locality manifest, they however also force things onto
us that are non-physical or hard to work with, for example gauge symmetries
and virtual particles. So even if there were no four different forces that
could maybe be unified into one, there would still be a lot of issues with
quantum field theory.

 _However, the dark matter problem stands out as one where measurements do not
line up with theory, and seems more of a classic example of how we 've
typically "turned the crank" on making progress in the past._

It is of course true that dark matter is in a certain sense a more tangible
problem, but on the other hand there is the problem that there are so many
different suggested resolutions. Astronomical and cosmological observations
may be the way to go for modified gravity or small black holes, particle
detector experiments may be the way for weakly interacting massive particles,
and each other resolution requires probably its own set of experiments. So
that problem seems not so much that nobody is investing the effort but that we
are not really sure where to look and for what. And in case of things like
weakly interacting massive particles we somewhat come back to extending the
standard model because such extensions may better inform us where to look.

------
acqq
It's exactly how "science is supposed to work" when the experiments don't
confirm the expectations of some theoretical physicists:

"killing off theories is simply how science is supposed to work" "“This is
what we do all the time, put forward a working hypothesis and test it,” said
Enrico Barausse of the Astrophysics Institute of Paris, who has worked on
MOND-like theories. “99.9 percent of the time you rule out the hypothesis; the
remaining 0.1 percent of the time you win the Nobel Prize.”"

(from [https://www.quantamagazine.org/troubled-times-for-
alternativ...](https://www.quantamagazine.org/troubled-times-for-alternatives-
to-einsteins-theory-of-gravity-20180430/) )

Of course everybody hopes to be in the team who "predicted" some discovery,
and the "most obvious" predictions have always be more expected. But the
nature simply is, and doesn't have to be "kind" to this or that theoretical
physicist.

------
ankurdhama
I don't like the words "laws of nature". It is another example of
anthropomorphism. Law is something that only make sense in the human social
context. All those so call laws are just some generalisations that are
extracted from the observations that we have observed in nature and most
importantly those observations are a very tiny tiny portion of the all
possible observations space of all of universe.

------
aj7
IMHO the real action in physics is the appearance of simple, clear-cut
phenomena arising in complex systems.

~~~
eigenspace
Condensed matter physics is so often overlooked by science communicators it's
tragic. Though to be fair, its an incredibly hard thing to explain to
laypeople.

------
aj7
The Science review quoted has been since edited “to remove an unattributed
quote.” It appears to me to be quite reasonable.

------
tim333
I've got a theory that the next break though, figuring out quantum gravity and
that won't come from physical experiments but from AI. Advanced physics is
really hard on the human brain (physics drop out here) and in the way the
AlphaGo was able to see new strategies that eluded humans for centuries I'm
guessing some future AI will be able to figure out interesting new physics
theories that we've missed.

------
sidek
To me, the criticism of the Science review that this book offers no
alternative paths forward is very strong. This is because when blundering
around in the darkness to find truth, there are no good algorithms. If you
could tell a high energy theorist a better algorithm to find good problems to
work on, they would listen. But if all you can do is point out that their
algorithm is suboptimal: well, sure. Of course it's suboptimal: we know, we
just have no better search algorithms in physics-theory-space.

Woit and company seem really invested in smearing high energy theory in front
of popular audiences. A book-long `look at the fact that this algorithm is
really slow!!!' is a sigh-worthy addition.

It's well acknowledged in the field that SUSY, string theory, etc. are very
incomplete ideas. No one is saying they have the full story, and I don't think
anyone expects to have the full story anytime soon.

So what have people been doing?

1) People have been expositing our `best guess' theory, which /is/ string
theory. We have really good tests of quantum field theory, and really good
reasons to think that `the most natural' generalisation is string theory.
We're not cocky enough to claim that string theory /is/ the generalisation,
just that it's a really good candidate and isn't it worth spending a vanishing
fraction of GDP to explore it and see how good of a candidate it really is?
Like, an incredibly larger amount of money is spent on innovating ways to get
people to look at advertisements. It doesn't seem like there is a high bar to
pass to justify the existence of studying this stuff.

Of course, a lot of effort goes into finding better guesses. Supersymmetry has
been under the gun since the LHC turned on, and tons of effort has been and is
spent thinking about the alternatives. Supersymmetry just remains a strong
enough idea in comparison to the alternatives people have proposed that people
think it's the best idea to explore. And as time goes on and supersymmetry
looks weaker and weaker, more people do spend time looking for good
alternatives.

2) People have been using tools from string theory to tell us about ordinary
quantum field theories. Dualities like ADS/CFT are huge right now. Lots of
really good ideas have come from high energy theory in recent years. ADS/CFT
is a string-theoretic duality which teaches us a lot about statistical
mechanical systems, things that definitely are testable. So string theory has
been testably productive, as applied to the study of quantum field theories
and statistical mechanics.

3) Also, the idea of topological quantum field theory is a recent innovation
of high energy theory, hardly fully explored, and has been hugely important
for modern mathematics.

I think these activities are pretty reasonable.

~~~
b1daly
I disagree that that is a fair criticism, that a person shouldn’t criticize
the state of “physics” as a professional practice if they don’t have better
solutions.

I read Lee Smolin’s “The Trouble With Physics,” covering similar terrain, and
his book was not presented as a work of science: it was rather a book about
the sociology of science, and how the structures in place controlling the
resources for research were going astray, by continuing to support,
professionally, work in areas that were not proving fruitful, and limiting
resources that might go towards finding new solutions.

Lost In Math sounds very interesting, as the author has decided to speak with
leading researchers about their work, at a time when the validity of that work
is being questioned.

That’s a worthy topic.

------
poster123
Particle physics is the most glamorous branch of physics, but I agree with the
book author that little progress is being made. In what branches of
theoretical physics could a brilliant young person have a good chance of
making important contributions?

~~~
scentoni
Condensed matter theory. Consider: there is only one vacuum, the background
upon which all of HEP/cosmology is set, and one collection of particles (the
Standard Model). On the other hand, there are vast numbers of different
crystal structures and non-crystalline phases of matter, each of which defines
a different background with different properties and different particles. Each
substance defines a new universe, which ultimately emerges from the Standard
Model particles in the vacuum, but can be much more fruitfully studied on its
own terms.
[https://en.wikipedia.org/wiki/Condensed_matter_physics](https://en.wikipedia.org/wiki/Condensed_matter_physics)
[https://en.wikipedia.org/wiki/Quasiparticle](https://en.wikipedia.org/wiki/Quasiparticle)

~~~
carapace
Reminds me of "Plasma Crystals": dust in plasma can form _crystals_.

> Dusty plasmas are interesting because the presence of particles
> significantly alters the charged particle equilibrium leading to different
> phenomena. It is a field of current research. Electrostatic coupling between
> the grains can vary over a wide range so that the states of the dusty plasma
> can change from weakly coupled (gaseous) to crystalline. Such plasmas are of
> interest as a non-Hamiltonian system of interacting particles and as a means
> to study generic fundamental physics of self-organization, pattern
> formation, phase transitions, and scaling.

[https://en.wikipedia.org/wiki/Dusty_plasma](https://en.wikipedia.org/wiki/Dusty_plasma)

