Sci.Physics.Foundations

Yablon wrote: ↑Fri Mar 25, 2022 7:23 am Dear friends:

It has been awhile, I hope everybody is well during these trying times.

I wanted my friends here to know that I am putting together a set of YouTube talks on unifying general relativity and quantum mechanics. The focus is on the geometrodynamic vacuum first exposited by Wheeler in the 1950s, and the black hole thermodynamics developed by Bekenstein and Hawking in the 1970s and 1980s. You can view my new channel, titled "let's talk about physics," at the link here: https://www.youtube.com/channel/UCLDYZN ... EIl1wpcOjQ.

The first talk, titled "quantum geometrodynamics: a sixty five year retrospective," can be viewed here: https://youtu.be/8_v8cz9-7CQ.

I am going to gradually roll this out, and would appreciate hearing your reactions and suggestions as I do so.

Best to all,

Jay

jreed wrote: ↑Sat Mar 26, 2022 9:32 am A very interesting presentation. It's difficult for me to follow it, however. I have trouble reading what you put on the whiteboard. Do you have a hard copy available? Maybe in PDF form. That would make it easier to understand since it would be possible to cross reference and understand each formula.

gill1109 wrote: ↑Fri Mar 25, 2022 11:21 pm Very nice! I like the painting. Watch your eyes though. You repeatedly look to one corner and your expression changes, this is distracting. Practice makes perfect!

jreed wrote: ↑Mon Mar 28, 2022 7:23 am I have many books on general relativity. I also have a copy of Wheeler's book Geometrodynamics from 1962 which goes into his work on non-quantized Geometrodynamics. In it he tried to build a neutrino using only geometrodynamics. He could not do it. The problem he ran into was trying to build a particle with spin 1/2. He stated in one of these papers in this book that unless this problem could be solved, geometrodynamics was not going to be useful for elementary particles. In his later book on general relativity, "Gravitation" by Misner, Thorne and Wheeler, no mention is made of geometrodynamics, and only one short reference to geons, which are short lived structures built from the space-time structure. Has the problem of spin been solved?

jreed wrote: ↑Mon Mar 28, 2022 7:23 am I have many books on general relativity. I also have a copy of Wheeler's book Geometrodynamics from 1962 which goes into his work on non-quantized Geometrodynamics. In it he tried to build a neutrino using only geometrodynamics. He could not do it. The problem he ran into was trying to build a particle with spin 1/2. He stated in one of these papers in this book that unless this problem could be solved, geometrodynamics was not going to be useful for elementary particles. In his later book on general relativity, "Gravitation" by Misner, Thorne and Wheeler, no mention is made of geometrodynamics, and only one short reference to geons, which are short lived structures built from the space-time structure. Has the problem of spin been solved?

Yablon wrote: ↑Mon Mar 28, 2022 10:52 am

jreed wrote: ↑Mon Mar 28, 2022 7:23 am I have many books on general relativity. I also have a copy of Wheeler's book Geometrodynamics from 1962 which goes into his work on non-quantized Geometrodynamics. In it he tried to build a neutrino using only geometrodynamics. He could not do it. The problem he ran into was trying to build a particle with spin 1/2. He stated in one of these papers in this book that unless this problem could be solved, geometrodynamics was not going to be useful for elementary particles. In his later book on general relativity, "Gravitation" by Misner, Thorne and Wheeler, no mention is made of geometrodynamics, and only one short reference to geons, which are short lived structures built from the space-time structure. Has the problem of spin been solved?

Also, take a look at https://physics.mcmaster.ca/phys3mm3/no ... isspin.pdf by Ohanian, from 1984. I audited Ohanian's course in special and general relativity at RPI in 1981 (five years after I graduated from the MIT undergraduate program), and also met with him privately on a number of occasions. On one such occasion, he handed me a slip of paper with two references printed on it: Wheeler's 1957 paper, and his 1962 book that you mention above, and told me that I should study those thoroughly, which I did. They became a sort of physics "bible" for me. Because I had deliberately taken it upon myself to study SR and GR and geometrodynamics before studying particle physics and quantum theory (the reverse order of how almost everyone else studies physics), I came to see the SR and GR as the "gold standard" of physics and could never be satisfied (and still am not satisfied) until I can understand particle physics and GR as simply and cleanly as I can understand SR and GR. While I was not formally enrolled in the physics department at RPI (again, I was an "audit" student), I regard Ohanian as my "thesis advisor," and Ohanian in turn, was one of many students who did their graduate work under Wheeler.

It is also a very good idea to take a look at Wald's book on General Relativity. Published in 1984, it was one of the first very serious studies of GR in view of Bekenstein / Hawking thermodynamics, which at the time was still new. The goal of my present work, starting with geometrodynamics and black hole thermodynamics, is to carry through and consummate the GR and QM unification that Wald envisioned.

Yablon wrote: ↑Sun Mar 27, 2022 12:17 pm

gill1109 wrote: ↑Fri Mar 25, 2022 11:21 pm Very nice! I like the painting. Watch your eyes though. You repeatedly look to one corner and your expression changes, this is distracting. Practice makes perfect!

Thanks, that painting belonged to my mom and dad and was in the entry area of the house where I grew up.

The "one corner" was where I hung the document I was reading from. I am not good at reading on camera. I much prefer just talking extemporaneously with a clipboard sidekick as I do in the 1 hour video retrospective on quantum geometrodynamics.

FrediFizzx wrote: ↑Mon Mar 28, 2022 11:22 am

Yablon wrote: ↑Mon Mar 28, 2022 10:52 am

jreed wrote: ↑Mon Mar 28, 2022 7:23 am I have many books on general relativity. I also have a copy of Wheeler's book Geometrodynamics from 1962 which goes into his work on non-quantized Geometrodynamics. In it he tried to build a neutrino using only geometrodynamics. He could not do it. The problem he ran into was trying to build a particle with spin 1/2. He stated in one of these papers in this book that unless this problem could be solved, geometrodynamics was not going to be useful for elementary particles. In his later book on general relativity, "Gravitation" by Misner, Thorne and Wheeler, no mention is made of geometrodynamics, and only one short reference to geons, which are short lived structures built from the space-time structure. Has the problem of spin been solved?

Also, take a look at https://physics.mcmaster.ca/phys3mm3/no ... isspin.pdf by Ohanian, from 1984. I audited Ohanian's course in special and general relativity at RPI in 1981 (five years after I graduated from the MIT undergraduate program), and also met with him privately on a number of occasions. On one such occasion, he handed me a slip of paper with two references printed on it: Wheeler's 1957 paper, and his 1962 book that you mention above, and told me that I should study those thoroughly, which I did. They became a sort of physics "bible" for me. Because I had deliberately taken it upon myself to study SR and GR and geometrodynamics before studying particle physics and quantum theory (the reverse order of how almost everyone else studies physics), I came to see the SR and GR as the "gold standard" of physics and could never be satisfied (and still am not satisfied) until I can understand particle physics and GR as simply and cleanly as I can understand SR and GR. While I was not formally enrolled in the physics department at RPI (again, I was an "audit" student), I regard Ohanian as my "thesis advisor," and Ohanian in turn, was one of many students who did their graduate work under Wheeler.

It is also a very good idea to take a look at Wald's book on General Relativity. Published in 1984, it was one of the first very serious studies of GR in view of Bekenstein / Hawking thermodynamics, which at the time was still new. The goal of my present work, starting with geometrodynamics and black hole thermodynamics, is to carry through and consummate the GR and QM unification that Wald envisioned.

All good stuff but is there another way to get elementary fermion spin into GR besides gravitational torsion? That is what I am interested in knowing.

FrediFizzx wrote: ↑Wed Mar 30, 2022 5:54 am While I'm waiting for Jay to answer my question, I will post a bit more about the unification issue. There is no problem at the low energy scale as gravity has been successfully quantized for that for years now with gravitons. Most of the problems are at the high energy Planck scale because GR is not renormalizable. Gravitational torsion can solve those problems by making renormalization a non-issue. IOW, gravitational torsion puts the brakes on near Planck scale.

FrediFizzx wrote: ↑Wed Mar 30, 2022 5:54 am While I'm waiting for Jay to answer my question, I will post a bit more about the unification issue. There is no problem at the low energy scale as gravity has been successfully quantized for that for years now with gravitons. Most of the problems are at the high energy Planck scale because GR is not renormalizable. Gravitational torsion can solve those problems by making renormalization a non-issue. IOW, gravitational torsion puts the brakes on near Planck scale.