
The Admiral of the String Theory Wars (2015) - dnetesn
http://nautil.us/issue/24/error/the-admiral-of-the-string-theory-wars
======
Communitivity
What matters is not the man, but the math. Regardless of who he is, are his
critiques of the string theory math sound? As a dabbler in theoretical physics
I don't have the skill to judge. What I am interested in, and only
tangentially related, is someone doing a good comparison and contrast of the
octonion theories and string theories. For more on octonions see
[https://www.quantamagazine.org/the-octonion-math-that-
could-...](https://www.quantamagazine.org/the-octonion-math-that-could-
underpin-physics-20180720/),
[http://physics.oregonstate.edu/~tevian/octonions/](http://physics.oregonstate.edu/~tevian/octonions/).

~~~
auntienomen
There really isn't any comparison between string theory and the octonion
"theories".

String theory is a fairly well-developed mathematical theory. We don't
understand everything about it, of course, but we really do know quite a bit.
The situation is comparable to that of quantum electrodynamics in the 1960s;
we've got enough of a theory that we can do reliable computations, but we're
still missing some important concepts.

The octonion theory isn't a theory at all yet. Assuming that it will
eventually become a theory, what we have now is more like Bohr's early quantum
mechanical models or de Broglie's wave-particle duality. We've got some
heuristics and some numerical coincidence and some toy models that suggest
there might be something there. But no one has actually found a mathematical
model that extends or explains the Standard Model of particle physics.

------
amai
Admiral or just crackpot?

[https://motls.blogspot.com/2016/02/the-utter-insanity-of-
woi...](https://motls.blogspot.com/2016/02/the-utter-insanity-of-woits-
rutgers.html)

------
snarfy
I've never found a good description or explanation of string theory for the
layman. I look, but then I always run into Brian Greene.

I did find this video[1], where a professor explains why he at least believes
there is something to it. Tl;dr - they weren't looking for strings. They sort
of 'popped out' of the equations.

[1] =
[https://www.youtube.com/watch?v=Q8ccXzM3x8A](https://www.youtube.com/watch?v=Q8ccXzM3x8A)

~~~
nerdponx
My understanding was that the original string idea arose naturally, but as
they developed the idea further it started (out of necessity) to take on the
familiar bizarre attributes like extra dimensions and supersymmetry. Sometimes
I wish I knew the math behind all of this, but I only have so much time on
this earth and I have other things I want to do with it.

~~~
duxup
Also my layman's understanding is that there is a lot of different math that
fits string theory.... not just one, that kinda raises questions about what
math is right if any of it is.

~~~
tzs
My layman's understanding, based on just having finished reading Brian
Greene's "The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest
for the Ultimate Theory" [1], which was recently a Prime Reading selection
(free to borrow for Prime Members), is that is that yes, it started out as one
theory, with 10 dimensions, and then other forms were discovered, until they
had 5 different string theories. That was the situation around 1985.

It's important to note that the equations of string theory (both when it was
one theory and when it was 5 theories were beyond our ability to solve
exactly. We could only approximate them, originally with things called
"perturbation methods".

Perturbation methods involve solving something for the big influences, then
adding in corrections to deal with smaller influences. For example, suppose
you wanted to calculate the orbit of a small moon in a close orbit around a
large planet. You could first calculate what the orbit would be in a universe
that just has that planet and moon--we can do that exactly. Then you could add
in the small differences that would be caused by their sun and other planets
in their system--the perturbations caused by the sun and other planets.

If, however, you had a planet with two large moons, you might not be able to
solve it for just the planet and one moon, then make small corrections for the
other moon and the sun, because the influences of the other moon is not small.
The exact solution for one planet and moon is just too far off from the final
solution for the former to be tweakable into the later.

There's a thing called the "string coupling constant". Perturbation methods
can only be used in the 5 string theories when the coupling constant is less
than 1. Eventually they found out how to solve some problems in each of the
theories even with coupling constants larger than 1, and to the surprise of
most they found that the 5 theories could be split into 3 groups.

One group contained two of the 5 theories. A universe following one of those
theories with a coupling constant of, say 0.5, would be identical to a
universe following the other theory with a coupling constant of 2.0. The two
theories are said to be duals of each other.

Another group contained just one theory. That theory was dual of itself. That
is, a universe following that theory with a coupling constant of 0.5 would be
identical to a universe following that theory with a constant of 2.0.

The final group contained the remaining two of the 5 theories. I'm having
trouble remembering how those were connected.

Anyway, somewhere along figuring out that last group, it was found that low
energy point-particle approximations of some of the string theories gave some
of the 10-dimenensional supergravity theories that had been worked on before
string theory to try to unify gravity and QM.

Then in 1995 Witten showed that if you took some of the string theories and go
from low to high coupling constant, the physic you get has a low energy
approximation that matches 11-dimensional supergravity.

Anyway, where they got to from there was that the 5 string theories had come
out 10-dimensional due to the fact that they could only approximately solve
the equations, and that string theory actually was an 11-dimensional theory,
and the 5 string 10-dimensional theories (and 11-dimenensional supergravity)
are just different perspectives on the one 11-dimensional theory that you get
when you make certain approximations or take it to certain limits.

(I may have botched an arbitrarily large amount of the above, so caution is
called for)

[1] [https://www.amazon.com/Elegant-Universe-Superstrings-
Dimensi...](https://www.amazon.com/Elegant-Universe-Superstrings-Dimensions-
Ultimate-ebook/dp/B001P7GGRS)

------
tim333
Some prior discussion
[https://news.ycombinator.com/item?id=10783032](https://news.ycombinator.com/item?id=10783032)

------
duxup
Admiral? And desktop support?

Not sure those go together.

~~~
jvkersch
It's worth checking out Peter Woit's homepage at
[http://www.math.columbia.edu/~woit/](http://www.math.columbia.edu/~woit/) and
looking beyond the blog and his role as a string theory skeptic. He teaches a
number of classes and has a book about quantum mechanics and representation
theory that has gotten a lot of favorable reviews. Not sure I'd classify this
guy as your average helpdesk guy ;)

~~~
erric
I inferred doing the computer support was something he just liked to do.
Everyone needs a hobby :)

~~~
jvkersch
That's a good point, and probably what GP was hinting at. Thanks for pointing
that out :)

