
How the belief in beauty has triggered a crisis in physics - mpweiher
https://www.nature.com/articles/d41586-018-05374-9
======
ISL
The crisis (if it exists) is not triggered by a belief in beauty, but by the
simple fact that LHC hasn't yet seen anything "new" (beyond the very-important
success of the Higgs discovery).

The observation of the apparent non-existence of something (supersymmetry, in
this case) is at least as important as the existence of something.
Supersymmetry is one of high-energy physics' best guesses as to the nature of
the universe. If that turns out not to be true, we have learned something very
important.

    
    
      "Thirty spokes share the wheel's hub;
      It is the center hole that makes it useful.
      Shape clay into a vessel;
      It is the space within that makes it useful.
      Cut doors and windows for a room;
      It is the holes which make it useful.
      Therefore profit comes from what is there;
      Usefulness from what is not there."
      Tao Te Ching - Lao Tzu - Chapter 11
      (translation by Gia-fu Feng and Jane English)
    
    

Physics is alive and well; there are plenty of big open problems with strong
experimental backing:

How does gravity connect with the rest of physics?

What is the nature of dark energy?

What is the nature of dark matter?

Where is the rest of the CP violation?

What gives neutrinos mass?

(And, the doozies that are so hard to answer that nobody touches them: Why
does time have a direction? Is there something underlying quantum mechanics?)

~~~
Zanni
The crisis that Hossenfelder is addressing is that there has been no
significant progress that's been experimentally verified in fundamental
physics since the birth of string theory in the 1980s. Yes, there are a lot of
big open problems, but they remain open. Yes, we have recently found
experimental evidence for things like the Higgs boson, but that was first
predicted in the 1960s. Yes, we can rule out some versions of string theory
thanks to LHC results, but there are a vast multitude of string theories, and
that's not a lot to show for nearly 40 years.

~~~
gus_massa
Some results that I remember just now:

* There is a recent 4.5+4.8 sigma excess in neutrinos oscillation that hints a new neutrino [https://arstechnica.com/science/2018/06/weird-neutrino-exces...](https://arstechnica.com/science/2018/06/weird-neutrino-excess-wont-go-away-hints-at-new-physics/) [technical note, you can't add sigmas naively, 4.5+4.8=6.1]

* The value of the magnetic moment of the muon (g) is too high. IIRC this result has only a 2.5 or 3 sigma, so it's far from confirmed.

* There are some experiment to prove that the neutrino is a majorana particle and that the neutrino and the anti-neutrino is the same particle. I don't remember any good announcement, so I think that the experiments have still too early results or the results are not interesting. [I don't like this theory, but many people that knows more than me like it.]

~~~
mcnamaratw
Sorry to nitpick but if we're adding variances, 4.5^2 + 4.8^2 = 6.6^2

~~~
gus_massa
Essentially yes (unless you are nearby an tactician or a journal referee). I
just copied the number from the article, I guess there is some rounding.

Also, the 6.2 or 6.1 is "unofficial" because it's difficult to mix results
from different experiments.

------
DoreenMichele
_“Why should the laws of nature care about what I find beautiful?”_

My suspicion is this is something we will forever wrestle with because
"beauty" is a proxy shorthand measurement for things of real value, but it is
confounded by an enormous and oft abused potential to use this fact
fraudulently. That which has real value is often appreciated for its beauty,
but the street doesn't run both ways. Seeking to make something look good
doesn't necessarily give it the more valuable underlying properties.

In GIS school, I learned that a good map will typically be described as
_beautiful_ , but a beautiful map isn't necessarily good. A good map is
elegantly designed to effectively convey information. When the goal is
achieved, high quality design also has inherent aesthetic appeal. But trying
to just make a map pretty doesn't make it more useful. In fact, it often makes
it less useful.

I think the same principle generalizes. I was born with serious respiratory
problems. I always had really lousy fingernails. With getting healthier, my
fingernails have grown stronger and prettier. This makes me suspect that
manicures and painted nails are about trying to enhance a signal of baseline
good health that is inherently valuable and attractive. But painting your
nails doesn't actually improve your respiratory health. Fake glued on nails
can give an appearance of health that isn't real.

~~~
BadThink6655321
Maybe we should care about beauty because Nature cares about beauty the way
she cares about symmetry. I’m just spitballing here, but maybe Emily Noether’s
intellectual heir will find a link between the conservation of energy and
Kolmogorov complexity (if this hasn’t already been shown).

~~~
DoreenMichele
Maybe _beauty_ is merely a word for "my brain has crunched vast amounts of
data and concluded that something very, very fundamentally appealing is going
on here and I shall call that by a word suggesting visual appeal because I
assessed that appeal with my eyes."

~~~
perl4ever
Maybe "beauty" is ultimately a name for symmetry, where symmetry is a name for
invariance under some transformation. And there is always a new type of
transformation to consider and therefore a new and perhaps more subtle form of
beauty.

------
Barrin92
>“Why should the laws of nature care about what I find beautiful?”

I find this question to be missing the fundamental point of scientific
endeavour. Nature obviously does not care about beauty, but scientists do
because extracting meaning and order (laws) from observations and building
models is the _very essence_ of scientific insight.

The goal of science is not to replicate nature, it is to build a model of
nature from which we can collect insights and make predictions, the model does
not need to 'conform to' nature. That's not the point. If that were the case
we could just dump the LHC data into a textbook. There is a great story writen
by Borges called _The Exactitude of Science_ where he creates the analogy of a
large, but useless map:

 _"... In that Empire, the Art of Cartography attained such Perfection that
the map of a single Province occupied the entirety of a City, and the map of
the Empire, the entirety of a Province. In time, those Unconscionable Maps no
longer satisfied, and the Cartographers Guilds struck a Map of the Empire
whose size was that of the Empire, and which coincided point for point with
it. The following Generations, who were not so fond of the Study of
Cartography as their Forebears had been, saw that that vast map was Useless,
and not without some Pitilessness was it, that they delivered it up to the
Inclemencies of Sun and Winters. In the Deserts of the West, still today,
there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all
the Land there is no other Relic of the Disciplines of Geography."_

~~~
pbhjpbhj
Such a map is far from useless - if you want to see any other area you don't
have to travel there; you can "visit" all areas, you can duplicate any one
area and experiment on how changes will affect it, etc.. It's only the bulk of
the map that makes it impractical, we actually now have maps that are pretty
close to that, we just found a way to make them less bulky.

I think the end goal of science actually is very close to the 1:1 scale map in
Borges' story [1] - we want to be able to say in any situation "if I take this
scenario and run it forward then what are the outcomes".

We can do this to some extent. We can predict paths of simple objects, we can
predict how macroscopic systems will play out to some degree of accuracy. We
can even predict the existence of particles and confirm the consistency of
such predictions in later observations.

Surely the goal is to make our predictions better, up to any limit the
universe gives. We want to be able to perfectly simulate the world - we don't
just want the 1:1 map, we want a 1x10^20:1 map with moving people, with
weather, with every possible feature that we can measure so that instead of
travelling to Ulaanbaatur and dropping a rocket motor from the troposphere we
can do that in the "map", and measure the effects in the map and so know what
the effects would be if that were to happen for real.

We can't use the Universe as it's own map, we can't arbitrarily look at it at
any scale, we can't run it back or duplicate it when we want to re-run
experiments, we can't visit any part without travelling, etc. - so we seek to
simulate it, through simplification because we can't currently simulate it any
other way. As we uncover ever better models we learn to simulate limited
sections or limited facets to a greater and greater degree.

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

~~~
Barrin92
but the predictability in this example comes from the function that maps one
state of the map to the next through time, not from any visible or high-
resolution feature in any particular snapshot of the map. You don't determine
the function and the skeleton of the map by increasing its resolution, you
obtain its functions by abstracting the unnecessary details away to figure out
what the important objects and regularities are.

If you want to figure out how the tube in London works you don't need a
photorealistic, lifelike copy of the subway system, you need an abstraction of
the network, its congestion, routes and so forth. Those are idealised mental
models that are simplifying the real system, but they are much more useful to
you than the real thing.

~~~
pbhjpbhj
Assuming you want to know how the tube works, as a passenger, independently of
other systems, then yes.

But if you're building a grand unified model of how London works then not only
do you want to be able to abstract certain facets, you also want to be able to
combine the models those abstractions create with data points to build a more
complex systemic model. You want to look at where the stations are in relation
to others, how the different transport networks link, what happens when a
tube-train stops - how does the effect ripple through the system and alter
what time a particular Pret-a-manger have to restock the sandwiches.

At that point the abstraction in to a simplified system that only describes
the tube is useless you need to combine the abstractions to model the entire
system - and you may be able to get there, except your model missed out
sunspot activity and a bus-driver turned the wrong way because their GPS was
marginally out and the Pret-a-manger manager missed the start of the shift and
now you have to eat Cheese instead of Mexican chicken.

In short you want your abstraction to be able to construct a model that is as
close as necessary for the purpose to the "photorealistic, lifelike copy" of
whatever it is you're seeking to predict. If you only wish to predict how many
stops you'll need to stay on the tube for then a simple tube map suffices. If
you want to predict airflow through the tube system and how it affects heat
exchange then a more complex model will be needed, with different abstractions
(preserving length of tunnels for example).

If you want to predict everything that it's possible to predict ...

[Disclaimer I've no idea what Pret's menu is.]

------
Animats
"Beauty", in this context, means "concise". Basic physical laws used to be
very short, with no arbitrary constants. "F = m _a ". "E = i_r". "E = m*c^2".
Kepler's laws. Maxwell's equations. The Schroedinger wave equation. When
researchers discovered the general rules that described how things worked,
they could be expressed as simple expressions. Physics progressed by
discovering such simple expressions.

Then that stopped working. That's the crisis.

~~~
whatshisface
> _Then that stopped working. That 's the crisis._

It didn't stop working. There isn't any unexplainable data - the opposite in
fact, too many explanations for the data we have.

~~~
fabatka
And in the case of string theory, we have explanation for data we don't have.

~~~
whatshisface
Every theory "explains data we don't have," for example F=ma makes a
prediction about the motion of a 10^100^100^100kg particle under a
10^100^100^100N force.

------
danbruc
I may be biased by the selection of physicist I watched lectures of, but they
would probably tend to disagree with the statement that physics got lost in
mathematics. Especially Nima Arkani-Hamed convincingly argues that we are
fundamentally looking at the universe from the wrong perspective. Relativity
and quantum theory are build around a few very fundamental principles like
locality and unitarity and somewhat surprisingly those principles single out a
very small set of possible theories that are compatible with those principles.

But on the other hand those principles seem to obscure a more fundamental and
simpler truth behind them. For example calculating scattering amplitudes may
require hundreds or thousands of terms from different Feynman diagrams with
more and more virtual particles but in the end they all cancel out.
Surprisingly again there are ways to arrive at the same results - BCFW
recursion relations and the amplituhedron - but with comparatively extremely
simple calculations. But unlike Feynman diagrams, which suggest a picture of
particles interacting locally in space, those calculations provide no picture
that can be easily matched against recognizable things.

The results are the same but there is nothing that looks like locally
interacting particles in there. This then suggests that things we currently
considered fundamental, for instance locality, are not fundamental, that they
emerge from something more fundamental. And this is where mathematics might be
really useful, you try to reformulate existing theories in new ways and maybe
you find a representation that is much simpler than what we have and maybe
that is what the universe is really like as compared to what it looks like to
us. And maybe that will also suggest new experiments to be done and which do
not require energies far beyond our current reach.

~~~
ravar
I have a question that didn't get answered when I talked to people about
amplituhedron. Do the higher k (dimension, I'm unsure) Grasmannian
calculations have any bearing on a world without super symmetry. Because
Nima's tool is only useful for super symmetric calculations then honestly it's
not very compelling. I want to be wrong, it's very beautiful math, but it
seems holy impractical for "real world" standard model physics.

~~~
danbruc
I am a total layman, so I don't know. But if I understood it right, the nice
final results relies on the use of Grassmannn variables which eventually
cancel out. Whether or not there is a path to non-supersymmetric theories, I
have no idea. But even if it fundamentally requires supersymmetry, the jury is
still out on whether or not the universe is supersymmetric even though the
best versions have now been ruled out.

------
sehugg
Happens to the best of us: [http://www.georgehart.com/virtual-
polyhedra/kepler.html](http://www.georgehart.com/virtual-
polyhedra/kepler.html)

------
plurinshael
Having studied both pure physics and pure mathematics, my impression is that
physicists don't really do mathematics, they use a pidgin form of symbolic
expression related to mathematics with the specific goal of studying natural
systems. And this is a pretty subtle point to explain to anyone who has not
experienced both cultures significantly. But the MO of studying systems that
can be measured in physical reality, is a constraining principle. Mathematics
is not constrained to so-called reality and as a result can fly higher and see
farther; it has a better imagination, if you will.

Burden me not with any reminders about reality, people needing to get up to
make the donuts or whatever. I know all that. I'm not knocking reality,
reality's great. Nor do I need reminding how beautiful and strange and wild
and cool some of the math in physics really can be. Utterly, utterly rad,
without a doubt. But working with such high-dimensional spaces, such high-
rank/high-variable transformations, and such high-density symbolic
representations, as physics seeks to do, requires a much freer and more
"artistic" approach than some kind of mental slavery to what can be seen. (By
which I mean, what can be measured.) Physicists need more pure math, and when
I say pure, I actually prefer the term theoretical math. Because physicists
need to design their own math, and that is in one sense what theoretical
mathematics means.

Physicists are better at what laypeople think of as mathematics--huge
whiteboards, filled with esoteric symbols, furrowed brows and chalk-stained
hands jittering through the air in some magnificent, halting dance of
frustration & eureka. That's what people think of when they think of "doing
mathematics". But physicists don't really do what mathematicians do, not
really, not completely. And all those purely esoteric maths that no one except
pure mathematicians ever get to see, say, topology, homology, algebraic
geometry, abstract algebra, etc, are hiding some real gems of thought.

I'd like to see Physics, finding itself at a halt, go and start to study all
the Mathematics it's been putting off.

~~~
vladTheInhaler
I'm pretty sure guys like Ed Witten are doing real math. Or at least he fooled
the mathematicians thoroughly enough that they gave him a fields medal. I'm
neither a physicist nor a mathematician, but your characterization seems a bit
unfair.

------
emilga
> “Why should the laws of nature care about what I find beautiful?”

This article is a nice counterpoint to Paul Dirac's speech in favour of
mathematical beauty in physical theories. [0]

Some quotes from Dirac:

> What makes the theory of relativity so acceptable to physicists in spite of
> its going against the principle of simplicity is its great mathematical
> beauty. [...] We now see that we have to change the principle of simplicity
> into a principle of mathematical beauty.

Interestingly, he also says:

> For example, only four-dimensional space is of importance in physics, while
> spaces with other numbers of dimensions are of about equal interest in
> mathematics.

> It may well be, however, that this discrepancy is due to the incompleteness
> of present-day knowledge, and that future developments will show four-
> dimensional space to be of far greater mathematical interest than all the
> others.

His prediction here was almost correct. Except it was physics that started to
take an interest in a higher number of dimensions.

[0]
[http://www.damtp.cam.ac.uk/events/strings02/dirac/speach.htm...](http://www.damtp.cam.ac.uk/events/strings02/dirac/speach.html)

------
seanwilson
You get this in mathematics too. The four colour theorem for example has an
"ugly" brute forced machine checked proof that's impractical for humans to
check.

Elegance and simplicity should be sought after, and ugly proofs can be an
indication that you're missing the right abstraction but I don't see why all
true statements should have an elegant proof.

------
marius_k
Goal of science is to predict as many phenomena with least amount of
assumptions. And minimizing assumptions usually makes a theory more beautiful.

But it is only my opinion and it is very subjective :).

------
millstone
Supersymmetry has not been found; however the top quark is an encouraging
precedent.

The top quark was predicted in the early 70s, and was expected to be found
soon. However colliders failed to find them, and its minimum mass kept getting
pushed up. It wasn't found until 1995, at a much higher energy than was
initially expected.

~~~
cosmojg
How did they account for the additional, unpredicted energy?

~~~
pbhjpbhj
AIUI ...

The presence of Top was predicted with the finding of Bottom, in order to
maintain symmetry. It was expected to have a higher energy otherwise it would
have been found ... but the energy turned out to be much higher. It wasn't
that it was predicted to be low energy and was found to have a higher energy,
it was that we knew it had higher energy than Bottom, but just not how high -
like climbing a convex hill covered in cloud, one can't see the top, and one
isn't sure until you reach it how high it's going.

It's my understanding that the unpredictably high energy hasn't properly been
accounted for but is believed to relate to Yukawa couplings.

The energy _was_ predicted within certain lower+upper bounds in '94 just prior
to the confirmation of the Top in '95, and a Nobel was awarded for that work
[relating to T parameters
([https://en.wikipedia.org/wiki/Peskin%E2%80%93Takeuchi_parame...](https://en.wikipedia.org/wiki/Peskin%E2%80%93Takeuchi_parameter))
which I don't claim to understand! 't Hooft and someone, erm, ...].

In part I believe it relates to how the Higgs works and whether the Higgs is
composite - possibly being comprised of Top and Anti-Top in one theory.

------
seycombi
Peter Woit writes regularly about this crisis on his blog "Not Even Wrong". He
wrote about Sabine Hossenfelder’s new book "Lost in Math" here
[https://www.math.columbia.edu/~woit/wordpress/?p=10314](https://www.math.columbia.edu/~woit/wordpress/?p=10314)

Feynman reminds us that "The first principle is that you must not fool
yourself, and you are the easiest person to fool."

------
8bitsrule
What are we going to replace the word 'crisis' with, once we've used it to
describe everything in modern life?

------
pbhjpbhj
Beauty is a feature of our Universe. It's not that surprising to find it also
in descriptions (equations, theories). Beauty is a Universe-y characteristic.

I imagine if we were in a different universe then our concept of beauty would
differ and perhaps, perhaps, conform more to the parameters of theories that
described that universe.

------
im3w1l
Is she suggesting us throwing out Occam's Razor? That's pretty radical.

~~~
BadThink6655321
I’d use another, less charitable, word. Finding the laws of physics isn’t any
different than finding a winning play in Go, except the search space is vastly
larger. If we aren’t going to pay for things like the Superconducting
Supercollider, we aren’t going to pay for a brute-force search to find the
laws of physics. We have to use heuristics to guide the search. “Beauty” has
worked in the past (Gell-Mann has a TED talk on this) so there’s no reason to
abandon it - until it doesn’t work. Then we’ll try something else. In addition
it took, what, 300 years to prove Fermat’s Last Theorem? Good grief. For hard
problems, 40 years is nothing.

~~~
sgt101
Brute force search isn't what solved Go. What was needed was a model with the
right information, not all the information or the most elegant or compressive
version of the information, but the right information. What "right" means in
this context is what we need to figure out!

~~~
jexah
To be clear, Go is not "solved". We just have AI they is strictly "very good"
at it (superhuman).

~~~
sgt101
fair point, poor language from me there.

------
gct
Humans find symmetry pretty, and fortunately experience has taught us time and
again that often the more symmetric solution is the better one.

~~~
resource0x
Not sure. Look at any symmetric figure, and compare it with a real flower, or
a leaf, or a bee. Which is more beautiful? The former looks dead in
comparison. I think the laws of nature are more similar in their "beauty" to
the latter.

~~~
perl4ever
I'm thinking vaguely of how, in a song, a "perfect rhyme" can be as jarring as
the lack of a rhyme where expected. I started listening for them and it seems
as though "general rhymes" are the rule. There's something about imperfect
symmetry in nature.

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

------
wmnwmn
Every major advance in physics has arrived with a new paradigm of mathematics,
usually more than one new paradigm. Beauty may be in the eye of the beholder,
but I doubt quantum gravity is going to be solved without the invention of
major new mathematics. It's not going to be found by tweaking some kludj no
matter how "ugly", nor hidden inside some long-familiar object (e.g., the E8
group...and for the record, Garrett Lisi is NOT a highly respected physicist.)

