
What every physicist should know about string theory - paulpauper
https://physicstoday.scitation.org/doi/10.1063/PT.3.2980?journalCode=pto
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madhadron
What I find most interesting about these articles showing up on Hacker News is
how discussion of abstruse details irrelevant to the bulk of progress in
physics or mathematics gets almost all the air time.

Compare the number of articles on string theory and physics beyond the
standard model to those on exotic materials, advances in turbulence, orbital
mechanics, modern elasticity, solar system formation, or foundations of
quantum mechanics. Is it that there is no tradition of popular writing that
makes people think that they have any insight beyond the wall of knowledge
necessary to understand these fields?

~~~
woodandsteel
Seems to me one solution would be for you and others who think like you to
regularly post links on HN to articles on these topics you believe are being
unjustly neglected.

~~~
Koshkin
... and see them being completely ignored. (That was the whole point, I
think.)

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roi
Peter Woit's critique of this article:
[http://www.math.columbia.edu/~woit/wordpress/?p=8068](http://www.math.columbia.edu/~woit/wordpress/?p=8068).

~~~
auntienomen
I've never found that Peter Woit's critiques of string theory match up very
well to the reality of what string theorists are doing.

Woit's critiques are of string theory as an extension of the Standard Model.
But most string theorists are not working on string theory trying to get
predictions about current energy frontiers. Rather, they are working on
understanding the mathematical structure of string theory and seeing what it
can teach us about analogous mathematical structures in quantum field theory.
(A now classic example: The first calculable models of 4-dimensional
confinement came out of string theory.)

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TwoNineA
Should be called string hypothesis.

~~~
madhadron
I would accept theory as the right word. A mathematical structure that has
been assembled for testing is generally referred by practitioners to as a
model or, if there is a collection of models and mathematics linking them, a
theory.

Unfortunately, a fully fleshed out theory with centuries of matching
experimental data is still called a theory.

~~~
chithanh
I think that is more of a namespace collision than anything else.

Even in mathematics, there are different definitions of "theory". One is that
a theory is a body of knowledge, like set theory or automata theory. This is
where I would group string theory as well.

Another definition from mathematical logic is that a theory is a set of axioms
and deduction rules. Fascinatingly, those have in common with scientific
theories that they can (if sufficiently complex) only ever be falsified, not
verified.

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perseusprime11
Did any physics enthusiasts read this paper?
[https://arxiv.org/abs/1001.0785](https://arxiv.org/abs/1001.0785)

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nategri
"Every" is a bit rich, considering we're likely 100s of years from testing it
directly.

~~~
Pharmakon
It isn’t clear that any amount of time would lead to it being falsifiable.

~~~
BadThink6655321
It has to agree with every prior measurement in Quantum Mechanics and
Relativity. That, in itself, is impressive.

~~~
Pharmakon
It also has developed some interesting mathematical tools and perspectives,
but as a TOE I think the growing skepticism is warranted. The worst outcome of
course being that M-Theory is accurate, but untestable. It would be a bitter
irony for humanity if our best theory required a galactic-scale collider to
test it!

~~~
caf
_It would be a bitter irony for humanity if our best theory required a
galactic-scale collider to test it!_

Doesn't that also mean that (in such a hypothetical situation) our best theory
says that our previously best theories will give accurate predictions up until
the point at which we observe something equivalent to a galactic-scale
collider? If so, that doesn't sound so bad to me.

~~~
whatshisface
The trouble is that strings is more of a framework for physics to fit in to
(like quantum mechanics) than it is a physical theory. There isn't a specific
list of string particles, just like there isn't a list of Schrodinger equation
particles. You have to add in whatever particles you discover, and then the
theory tells you how they move.

On the bright side, if there was a single particle that didn't move like a
string, string theory would be falsified. On the dim side, it's difficult for
anything to not move like a string, because string theory is so powerful as a
framework that you can get it to make just about anything consistent. What you
really want in physics is a brittle framework that only allows you to slot in
a few different behaviors.

It's kind of funny because programmers want the opposite thing that physicists
do. When your client asks for a behavior that you have painted yourself into a
corner against ever implementing your software has been "falsified," an
expensive disaster that you work very hard in advance to _prevent_! If you
made universes for a living, strings would be an ideal framework.

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orlandpm
I don’t think most PhD physicists know what a diffeomorphism is.

~~~
whatshisface
Ok, let me guess without looking it up... A diffeomorphism is a smooth map
that lets you switch coordinate systems.

(I sure hope that's not wrong.)

~~~
auntienomen
Pretty close. It's a smooth map with smooth inverse. If you've chosen chosen
coordinates, it will transform them for you.

I think most physicists probably have a reasonable intuitive idea what a
diffeomorphism is, since most have probably learned something about
relativity.

