5 ms·

The Admiral of the String Theory Wars (2015)

35 points by dnetesn 8y ago

tim333 8y ago
Some prior discussion https://news.ycombinator.com/item?id=10783032 https://news.ycombinator.com/item?id=10783032
duxup 8y ago
Admiral? And desktop support? Not sure those go together.
- jshaqaw 8y ago
  Einstein was a patent clerk. I am certainly not equipped to weigh in on the string theory debates but the ability to make serious intellectual contributions and the skills of navigating siloed academic hierarchies are not necessarily correlated.
- jvkersch 8y ago
  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 8y ago
    I inferred doing the computer support was something he just liked to do. Everyone needs a hobby :)
    - jvkersch 8y ago
      That's a good point, and probably what GP was hinting at. Thanks for pointing that out :)
  - auntienomen 8y ago
    He's not an average help-desk guy, but he's not a first rate researcher either. He produced some good lattice qft work in the late 70s/early 80s, then worked unsuccessfully on Chern-Simons theory for a while. Since then he hasn't produced any papers. For a PhD researcher, this is basically 'failure to launch'. (And to be fair, this is probably the most common outcome for STEM PhDs.)
snarfy 8y ago
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 8y ago
  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 8y ago
    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 8y ago
      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-Dimensions-Ultimate-ebook/dp/B001P7GGRS https://www.amazon.com/Elegant-Universe-Superstrings-Dimensi...
Communitivity 8y ago
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-underpin-physics-20180720/ https://www.quantamagazine.org/the-octonion-math-that-could-..., http://physics.oregonstate.edu/~tevian/octonions/ http://physics.oregonstate.edu/~tevian/octonions/.
- auntienomen 8y ago
  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 8y ago
Admiral or just crackpot? https://motls.blogspot.com/2016/02/the-utter-insanity-of-woits-rutgers.html https://motls.blogspot.com/2016/02/the-utter-insanity-of-woi...

35 points by dnetesn 8y ago

tim333 8y ago

Some prior discussion https://news.ycombinator.com/item?id=10783032 https://news.ycombinator.com/item?id=10783032

duxup 8y ago

Admiral? And desktop support? Not sure those go together.

jshaqaw 8y ago
Einstein was a patent clerk. I am certainly not equipped to weigh in on the string theory debates but the ability to make serious intellectual contributions and the skills of navigating siloed academic hierarchies are not necessarily correlated.
jvkersch 8y ago
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 8y ago
  I inferred doing the computer support was something he just liked to do. Everyone needs a hobby :)
  - jvkersch 8y ago
    That's a good point, and probably what GP was hinting at. Thanks for pointing that out :)
- auntienomen 8y ago
  He's not an average help-desk guy, but he's not a first rate researcher either. He produced some good lattice qft work in the late 70s/early 80s, then worked unsuccessfully on Chern-Simons theory for a while. Since then he hasn't produced any papers. For a PhD researcher, this is basically 'failure to launch'. (And to be fair, this is probably the most common outcome for STEM PhDs.)

snarfy 8y ago

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 8y ago
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 8y ago
  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 8y ago
    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-Dimensions-Ultimate-ebook/dp/B001P7GGRS https://www.amazon.com/Elegant-Universe-Superstrings-Dimensi...

Communitivity 8y ago

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-underpin-physics-20180720/ https://www.quantamagazine.org/the-octonion-math-that-could-..., http://physics.oregonstate.edu/~tevian/octonions/ http://physics.oregonstate.edu/~tevian/octonions/.

auntienomen 8y ago
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 8y ago

Admiral or just crackpot? https://motls.blogspot.com/2016/02/the-utter-insanity-of-woits-rutgers.html https://motls.blogspot.com/2016/02/the-utter-insanity-of-woi...