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models:speculative_models:grand_unified_theories [2018/02/19 17:06]
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models:speculative_models:grand_unified_theories [2018/05/22 14:23] (current)
jakobadmin [Criticism]
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-====== ​ Grand Unified ​Theories ​======+====== ​ Grand Unified ​Models ​======
    
 +
 +<tabbox Intuitive> ​
 +
 +<​blockquote>​
 +The similarities between the vacuum of space and low-temperature phases of matter are legendary in physics. Not only are phases static,​uniform quantum states, but their most subtle internal motions are physically indistinguishable om elementary particles very generally.3This is one of the most astonishing facts in science, and something students always find upsetting and difficult to believe. But they even­tually become convinced a er looking at enough experiments,​ for the evidence is plenti l and consistent. In fact, the more one studies the mathematical descriptions of cold phases, the more accustomed one gets to using the parallel terminologies of matter and space inter­changeably. Thus instead of a phase of matter we speak of a vacuum.Instead of particles we speak of excitations. Instead of collective mo­tions we speak of quasiparticles. The pre x "​quasi"​ turns out to be a vestige of the historical battles over the physical meaning of these ob­jects and conveys no meaning. In private conversations one drops the pretense and refers to the objects as particle
 +
 +[...]
 +
 +The vacuum, when cooled from very high temperatures,​ is thought to undergo stepwise events called unification transitions,​ in which the known forces of nature split off sequentially from their fundamental parent. Similarly, holmium metal, a rare earth element, when cooled from very high temperature,​ first condenses into a liquid at 2993 degrees Kelvin, then solidifies at 1743 degrees, then develops a special kind of spiraling magnetism at 130 degrees, then tils the spiral to make weak ferromagnet at 20 degrees. Between 130 degrees and 20 degrees the pitch of the spiral varies continuously,​ as though it were a rubber screw being stretched along its axis. With each of these transitions the "​forces"​ between electrons in the metal transmitted by various elastic distortions of the ordered state split off from the fundamental parent in beautiful and apt analogy with what occurs in the vacuum. The temperatures required to see the unification transitions of the vacuum cannot be achieved in the laboratory, or even in the centers of the largest stars, so the evidence for unification is indirect, but it nicely parallels what one would find in the tilted spiral magnet if one's experiments could reach only long length and time scales. One of the strongest of these bits of evidence is [[advanced_tools:​renormalization|renormalizability]],​ an effect that causes the accessible measurements to be simple and redundant (one measurement predicts another) but that at the same time is incapable of revealing anything about the forces at the top of the hierarchical tree. 
 +
 +[...]
 +
 +There are numer­ous experimental indications that the vacuum emerges in a hierarchy of phase transitions in which the various forceS differentiate from each other....
 +
 +If renormalizability of he vacuum is caused by proximity to phase transitions th the search for an ultimate theory would been doomend on two counts: it would not predict anything even if you found it, and it could not be falsified.
 +
 +<​cite>​page 112 in "A different Universe"​ by Robert Laughlin</​cite>​
 +</​blockquote>​
 +
 +
 +  ​
 +<tabbox Concrete> ​
 +
 +  * Grand Unified Theories by Graham Ross
 +  * Grand Unification with and without Supersymmetry by Ed Witten
 +  * Grand Unification with and Without Supersymmetry And Cosmology Implications by C Kounnas et. al.
 +  * http://​users.physics.uoc.gr/​~rosen/​projects/​gutFive.pdf
 + 
 +<tabbox Abstract> ​
 +
 +  * [[https://​arxiv.org/​abs/​0904.1556|The Algebra of Grand Unified Theories]] by John C. Baez, John Huerta
 +  * [[https://​inspirehep.net/​record/​10204/​|Group Theory for Unified Model Building]] by R. Slansky
 +  * [[http://​discovery.ucl.ac.uk/​1471160/​1/​thesis.pdf|Model Building and Phenomenology in Grand Unified Theories]] by Tomas E. Gonzalo Velasco
 +  * http://​jakobschwichtenberg.com/​resources-that-helped-me-understand-grand-unified-theories/​
 +
 +
 +  ​
 <tabbox Why is it interesting?> ​ <tabbox Why is it interesting?> ​
  
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 --> Matter-Antimatter Asymmetry # --> Matter-Antimatter Asymmetry #
  
-GUTs provide a natural framework to explain the observed matter-antimatter asymmetry in the universe. As already noted above a general implication of GUTs is that protons are no longer stable. Formulated differently,​ GUTs allow baryon number-violating interactions. This is one of three central ingredients,​ known as Sakharov conditions ​\cite{Sakharov:​1967dj}, needed to produce more baryons than antibaryons in the early universe. Thus, as D. V. Nanopoulos put it, "if the proton was stable it would not exist"​.+GUTs provide a natural framework to explain the observed matter-antimatter asymmetry in the universe. As already noted above a general implication of GUTs is that protons are no longer stable. Formulated differently,​ GUTs allow baryon number-violating interactions. This is one of three central ingredients,​ known as Sakharov conditions, needed to produce more baryons than antibaryons in the early universe. Thus, as D. V. Nanopoulos put it, "if the proton was stable it would not exist"​.
  
 <-- <--
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 is not the Standard Model (SM), is beyond the SM, but is the most standard is not the Standard Model (SM), is beyond the SM, but is the most standard
 physics beyond the SM. Most of us think that there should be something like a GUT.”<​cite>​[[http://​inspirehep.net/​record/​1642530/​files/​1641483_174-182.pdf|Altarelli]]</​cite></​blockquote>​ physics beyond the SM. Most of us think that there should be something like a GUT.”<​cite>​[[http://​inspirehep.net/​record/​1642530/​files/​1641483_174-182.pdf|Altarelli]]</​cite></​blockquote>​
-<tabbox Layman> ​ 
- 
-<​blockquote>​ 
-The similarities between the vacuum of space and low-temperature phases of matter are legendary in physics. Not only are phases static,​uniform quantum states, but their most subtle internal motions are physically indistinguishable om elementary particles very generally.3This is one of the most astonishing facts in science, and something students always find upsetting and difficult to believe. But they even­tually become convinced a er looking at enough experiments,​ for the evidence is plenti l and consistent. In fact, the more one studies the mathematical descriptions of cold phases, the more accustomed one gets to using the parallel terminologies of matter and space inter­changeably. Thus instead of a phase of matter we speak of a vacuum.Instead of particles we speak of excitations. Instead of collective mo­tions we speak of quasiparticles. The pre x "​quasi"​ turns out to be a vestige of the historical battles over the physical meaning of these ob­jects and conveys no meaning. In private conversations one drops the pretense and refers to the objects as particle 
- 
-[...] 
- 
-The vacuum, when cooled from very high temperatures,​ is thought to undergo stepwise events called unification transitions,​ in which the known forces of nature split off sequentially from their fundamental parent. Similarly, holmium metal, a rare earth element, when cooled from very high temperature,​ first condenses into a liquid at 2993 degrees Kelvin, then solidifies at 1743 degrees, then develops a special kind of spiraling magnetism at 130 degrees, then tils the spiral to make weak ferromagnet at 20 degrees. Between 130 degrees and 20 degrees the pitch of the spiral varies continuously,​ as though it were a rubber screw being stretched along its axis. With each of these transitions the "​forces"​ between electrons in the metal transmitted by various elastic distortions of the ordered state split off from the fundamental parent in beautiful and apt analogy with what occurs in the vacuum. The temperatures required to see the unification transitions of the vacuum cannot be achieved in the laboratory, or even in the centers of the largest stars, so the evidence for unification is indirect, but it nicely parallels what one would find in the tilted spiral magnet if one's experiments could reach only long length and time scales. One of the strongest of these bits of evidence is [[advanced_tools:​renormalization|renormalizability]],​ an effect that causes the accessible measurements to be simple and redundant (one measurement predicts another) but that at the same time is incapable of revealing anything about the forces at the top of the hierarchical tree.  
- 
-[...] 
- 
-There are numer­ous experimental indications that the vacuum emerges in a hierarchy of phase transitions in which the various forceS differentiate from each other.... 
- 
-If renormalizability of he vacuum is caused by proximity to phase transitions th the search for an ultimate theory would been doomend on two counts: it would not predict anything even if you found it, and it could not be falsified. 
- 
-<​cite>​page 112 in "A different Universe"​ by Robert Laughlin</​cite>​ 
-</​blockquote>​ 
- 
- 
-  ​ 
-<tabbox Student> ​ 
- 
-  * Grand Unified Theories by Graham Ross 
-  * Grand Unification with and without Supersymmetry by Ed Witten 
-  * Grand Unification with and Without Supersymmetry And Cosmology Implications by C Kounnas et. al. 
-  * http://​users.physics.uoc.gr/​~rosen/​projects/​gutFive.pdf 
-  
-<tabbox Researcher> ​ 
- 
-  * [[https://​arxiv.org/​abs/​0904.1556|The Algebra of Grand Unified Theories]] by John C. Baez, John Huerta 
-  * [[https://​inspirehep.net/​record/​10204/​|Group Theory for Unified Model Building]] by R. Slansky 
-  * [[http://​discovery.ucl.ac.uk/​1471160/​1/​thesis.pdf|Model Building and Phenomenology in Grand Unified Theories]] by Tomas E. Gonzalo Velasco 
-  * http://​jakobschwichtenberg.com/​resources-that-helped-me-understand-grand-unified-theories/​ 
- 
- 
-  ​ 
-<tabbox Examples> ​ 
- 
---> Example1# 
- 
-  
-<-- 
- 
---> Example2:# 
- 
-  
-<-- 
- 
 <tabbox FAQ> ​ <tabbox FAQ> ​
  
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   ​   ​
 <tabbox History> ​ <tabbox History> ​
 +  * [[http://​nautil.us/​issue/​46/​balance/​a-brief-history-of-the-grand-unified-theory-of-physics|A Brief History of the Grand Unified Theory of Physics]] by Lawrence Krauss
 <tabbox Criticism> ​ <tabbox Criticism> ​
 <​blockquote>"​Physics is littered with the corpses of dead unified field theories."​ <​blockquote>"​Physics is littered with the corpses of dead unified field theories."​
Line 135: Line 124:
 <​blockquote>​“People can construct models with higher symmetries and stand on their nose and try to avoid proton decay,” Nanopoulos said. “OK, you can do it, but … you cannot show it to your mother with a straight face.” https://​www.quantamagazine.org/​20161215-proton-decay-grand-unification/</​blockquote>​ <​blockquote>​“People can construct models with higher symmetries and stand on their nose and try to avoid proton decay,” Nanopoulos said. “OK, you can do it, but … you cannot show it to your mother with a straight face.” https://​www.quantamagazine.org/​20161215-proton-decay-grand-unification/</​blockquote>​
  
 +
 +----
 +
 +**Major Questions still unsolved in GUTs**
 +
 +  * The Hierarchy Problem, i.e. why $M_W/​M_{GUT} <​10^{-12}$.
 +  * The strong CP problem.
 +  * The cosmological constant problem.
 +  * The absence of gravity.
 +  * The family repetition problem, i.e. why are there three families.
 +  * The fermion mass spectrum. ​
 +
 +GUTs have nothing to say on these matters.
  
 ----- -----
models/speculative_models/grand_unified_theories.1519056369.txt.gz · Last modified: 2018/02/19 16:06 (external edit)