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http://www.shipov.com
In Einstein's 1915 GR prior to the introduction of the teleparallel Kibble-Shipov torsion field with the 6 anholonomic angular pre-Calabi-Yau coordinates for the orientation of the Einstein-Cartan tetrad frame mobile {e^a} (Riemann Curvature)uvwl = (Weyl Vacuum Curvature)uvwl + (1/2)[(curved metric)uwT(non-gravity source)vl + (curved metric)vlT(non-gravity source)uw - (curved metric)ulT(non-gravity source)vw - (curved metric)vwT(non-gravity source)ul] - (1/3)[(curved metric)uw(curved metric)vl - (curved metric)ul(curved metric)vw]T(non-gravity source) Tuv(Dark Energy/Matter) = (String Tension)/\zpf(curved metric)uv /\zpf = (Quantum of Area of World Hologram)^-1(1 - |Higgs Vacuum ODLRO Order Parameter|^2) /\zpf 0 is repulsive blue-shifting universal anti-gravity field (e.g. cosmic voids & Type 1a supernovae) /\zpf 0 is attractive red-shifting universal gravity field (e.g. Galactic halos & filaments) Dark regions are where /\zpf 0, bright filaments are where /\zpf 0. http://heasarc.nasa.gov/docs/cosmic/sheets_voids.html Problem is how to put Shipov's torsion field as a replacement for /\zpf, which he does in one of his papers on dark energy and torsion. |
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11) Derek Wise, MacDowell-Mansouri gravity and Cartan geometry,
available as gr-qc/0611154. Elie Cartan is one of the most influential of 20th-century geometers. At one point he had an intense correspondence with Einstein on general relativity. His "Cartan geometry" idea is an approach to the concept of parallel transport that predates the widely used Ehresmann approach (connections on principal bundles). It simultaneously generalizes Riemannian geometry and Klein's Erlangen program (see "week213"), in which geometries are described by their symmetry groups: EUCLIDEAN GEOMETRY -------------- KLEIN GEOMETRY | | | | | | | | v v RIEMANNIAN GEOMETRY -------------- CARTAN GEOMETRY Given all this, it's somewhat surprising how few physicists know about Cartan geometry! Recognizing this, Derek explains Cartan geometry from scratch before showing how it underlies the so-called MacDowell-Mansouri approach to general relativity. This plays an important role both in supergravity and Freidel and Starodubtsev's work on quantum gravity (see "week235") - but until now, it's always seemed like a "trick". What's the basic idea? Derek explains it all very clearly, so I'll just provide a quick sketch. Cartan describes the geometry of a lumpy bumpy space by saying what it would be like to roll a nice homogeneous "model space" on it. Homogeneous spaces are what Klein studied; now Cartan takes this idea and runs with it... or maybe we should say he *rolls* with it! For example, we could study the geometry of a lumpy bumpy surface by rolling a *plane* on it. If our surface is itself a plane, this rolling motion is trivial, and we say the surface is "flat" in the sense of Cartan geometry. But in general, the rolling motion is interesting and serves to probe the geometry of the surface. Alternatively, we could study the geometry of the same surface by rolling a *sphere* on it. Derek illustrates this with a picture of a hamster crawling around in a plastic "hamster ball", which is something you can actually buy for your pet hamster to let it explore your house without escaping or getting in trouble. (I've read about falling cats in papers on gauge theory, but this is the first mathematical physics paper I've read containing the word "hamster".) If our surface is itself a sphere of the same radius, this rolling motion is trivial, and we say the surface is flat in the sense of Cartan geometry - but now it's a different sense than when we used a plane as our "model geometry"! Which model geometry should we use in a given problem? It depends on which one best approximates the lumpy bumpy space we're studying! The ordinary formulation of general relativity fits into this framework, with a little work. Two well-known mathematical gadgets called the "Lorentz connection" and "coframe field" fit together to describe what would happen if we rolled a copy of Minkowski spacetime over the lumpy bumpy spacetime we live in. That's great if Minkowski spacetime is the best homogeneous approximation to the spacetime we live in. But nowadays we think the cosmological constant is nonzero, so the Universe is expanding in a roughly exponential way. This makes another model geometry, "deSitter spacetime", the best one to use! So, if we know Cartan geometry, we can use that... and we get something called the MacDowell-Mansouri formulation of gravity. Or, if we don't want our spacetime to have lumps and bumps - if we want it to look locally just like the Klein model geometry - we can use a different theory, a topological field theory called BF theory (see "week232"). In short, the passage from a topological field theory describing a "locally homogeneous" spacetime to full-fledged gravity with all its lumps and bumps is nicely understood in terms of how Cartan's approach to geometry generalizes Klein's! For more details, you'll just have to read Derek's paper. You might also try these: 12) Michel Biesunski, Inside the coconut: the Einstein-Cartan discussion on distant parallelism, in Einstein and the History of General Relativity, eds. D. Howard and J. Stachel, Birkhauser, Boston, 1989. This describes the correspondence between Cartan and Einstein. I believe this centered, not on Cartan geometry per se, but on the "teleparallel" formulation of gravity (see "week176"). But, they're somewhat related. 13) R. W. Sharp, Differential Geometry: Cartan's Generalization of Klein's Erlangen Program, Springer-Verlag, New York, 1997. This is the main textbook on Cartan geometry. But, it's probably best to read a few chapters of Derek's paper first, since the key ideas are presented more intuitively. My friend the geometer and analyst Rafe Mazzeo, whom I recently saw at Stanford, told me that Cartan geometry was all the rage these days. I'm embarrassed to say I hadn't know this! I think the kinds of Cartan geometry being intensively studied are related to conformal geometry, CR structures and stuff like that... Merry Christmas! Quote of the Week: "The Universe has as many different centers as there are living beings in it." - Alexander Solzhenitsyn http://www.shipov.com In Einstein's 1915 GR prior to the introduction of the teleparallel Kibble-Shipov torsion field with the 6 anholonomic angular pre-Calabi-Yau coordinates for the orientation of the Einstein-Cartan tetrad frame mobile {e^a} http://heasarc.nasa.gov/docs/cosmic/sheets_voids.html thus: I only write about stuff that I know about or, at least, have read about in the God-am newspapers. just note that, in many instances, there really is only "one side to the story" being reported, Darfur e.g. Isn't there a better forum for your warped political perspective than a news group on Buckminster Fuller? thus: so, how many proofs of pyhtagoras' theorem, can't you comprehend?... as for Hales' proof of Kepler's C., it never actually worked, as shown in one of the popularizing books on it, I think; it's kinda hard to find any overt admission of this on Hales' website, though ... and, he *did* prove an important related theorem.... this may also apply to the fourcolorconjecture, but several simplicifications of the computerized one have been done, so ... I believe Ribet on Wiles' "proof," although I'd rather learn how Fermat did it; at least, he made no other known mistakes. still, the characterization of the Fermat primes is an open problem, arguably more important than his "last." as for the nonexistence of a proof of RH or Goldbach C., quelle ridicule! And the bugs in the accepted proofs of the fundamental theorem of algebra by Girard, D´´ thus: completely interconsistent with your theory, two, since you can, now, have "travelled back" to them, at Langley or where ever, to tell them how to do it.... I'd call Art Bell; you should not let Al Beliek and John V. Neumann try to take the credit for it, based upon the Philedelphia Experiment, which everyone knows was just to test *radar* "invisibility," if you hadn't already preempted that in your Delorean.... don't drive over all of your great-great granchildren! you were referring to Normal CIA Remote Viewing, the kind that was completely ineffective (or completely hidden from sight, of course, because there's all of this great theory to back it "up" .-) "If we knew what it was we were doing, it would not just be called research; it would be also known as The Rectal Display Unit!" --J.Sarfatti thus: Harry Potter-affiliated stuff, in general -- like both Iraq wars). this just in: yesterday's (Tues,. Nov.15) *UCLA Daily Bruin* finally noted that darfur is entirely Muslim, though downplaying it AMAP. thus: Dick Cheeny, Don Rumsfeld and Osama bin Latin form a mission to Darfur, to prevent a war instead of to start one: if Darfur is "100% Muslim," then what's really going on, there? is it just aother British Quag for USA soldiers to get bogged into, with Iran, Iraq, Afghanistan et al ad vomitorium, under auspices of the UN and NATO? why won't the Bruin publish the fact of Islam on the ground, therein? thus: Why doesn't the [UCLA Daily] Bruin report that Darfur's populace is "100%" Muslim, according to the DAC's sponsor, Terry Saunders?... "99%" was the figure given by Brian Steidle, when I finally found him at the Hammer, after everyone else had left (he, his friend & I were the very last to leave!)... What could it possibly mean? --The Other Side (if it exists) |
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![]() Aluminium Holocene Holodeck Zoroaster wrote: 11) Derek Wise, MacDowell-Mansouri gravity and Cartan geometry, available as gr-qc/0611154. Elie Cartan is one of the most influential of 20th-century geometers. At one point he had an intense correspondence with Einstein on general relativity. His "Cartan geometry" idea is an approach to the concept of parallel transport that predates the widely used Ehresmann approach (connections on principal bundles). It simultaneously generalizes Riemannian geometry and Klein's Erlangen program (see "week213"), in which geometries are described by their symmetry groups: EUCLIDEAN GEOMETRY -------------- KLEIN GEOMETRY | | | | | | | | v v RIEMANNIAN GEOMETRY -------------- CARTAN GEOMETRY Given all this, it's somewhat surprising how few physicists know about Cartan geometry! Recognizing this, Derek explains Cartan geometry from scratch before showing how it underlies the so-called MacDowell-Mansouri approach to general relativity. This plays an important role both in supergravity and Freidel and Starodubtsev's work on quantum gravity (see "week235") - but until now, it's always seemed like a "trick". What's the basic idea? Derek explains it all very clearly, so I'll just provide a quick sketch. Cartan describes the geometry of a lumpy bumpy space by saying what it would be like to roll a nice homogeneous "model space" on it. Homogeneous spaces are what Klein studied; now Cartan takes this idea and runs with it... or maybe we should say he *rolls* with it! For example, we could study the geometry of a lumpy bumpy surface by rolling a *plane* on it. If our surface is itself a plane, this rolling motion is trivial, and we say the surface is "flat" in the sense of Cartan geometry. But in general, the rolling motion is interesting and serves to probe the geometry of the surface. Alternatively, we could study the geometry of the same surface by rolling a *sphere* on it. Derek illustrates this with a picture of a hamster crawling around in a plastic "hamster ball", which is something you can actually buy for your pet hamster to let it explore your house without escaping or getting in trouble. (I've read about falling cats in papers on gauge theory, but this is the first mathematical physics paper I've read containing the word "hamster".) If our surface is itself a sphere of the same radius, this rolling motion is trivial, and we say the surface is flat in the sense of Cartan geometry - but now it's a different sense than when we used a plane as our "model geometry"! Which model geometry should we use in a given problem? It depends on which one best approximates the lumpy bumpy space we're studying! The ordinary formulation of general relativity fits into this framework, with a little work. Two well-known mathematical gadgets called the "Lorentz connection" and "coframe field" fit together to describe what would happen if we rolled a copy of Minkowski spacetime over the lumpy bumpy spacetime we live in. That's great if Minkowski spacetime is the best homogeneous approximation to the spacetime we live in. But nowadays we think the cosmological constant is nonzero, so the Universe is expanding in a roughly exponential way. This makes another model geometry, "deSitter spacetime", the best one to use! So, if we know Cartan geometry, we can use that... and we get something called the MacDowell-Mansouri formulation of gravity. Or, if we don't want our spacetime to have lumps and bumps - if we want it to look locally just like the Klein model geometry - we can use a different theory, a topological field theory called BF theory (see "week232"). In short, the passage from a topological field theory describing a "locally homogeneous" spacetime to full-fledged gravity with all its lumps and bumps is nicely understood in terms of how Cartan's approach to geometry generalizes Klein's! Above was used a rolling sphere to interrogate the "lumpy-bumpy" surface, fair enough, the analogy is respected, however I couldn't find any mention as to how the sphere diameter would affect the result. A smaller sphere diameter would resolve a "lumpy-bumpy" surface with more accuracy. In that case, we could use the analogy of a higher energy photon to improve surface resolution, common in electron microscopes and X-rays, compared to visual light, (I'm sneaking in a bit of quantum theory). ((IMO, the Cartan philosophy leads to asymmetrical metrics, but that's just me)). Regards Ken S. Tucker For more details, you'll just have to read Derek's paper. You might also try these: 12) Michel Biesunski, Inside the coconut: the Einstein-Cartan discussion on distant parallelism, in Einstein and the History of General Relativity, eds. D. Howard and J. Stachel, Birkhauser, Boston, 1989. This describes the correspondence between Cartan and Einstein. I believe this centered, not on Cartan geometry per se, but on the "teleparallel" formulation of gravity (see "week176"). But, they're somewhat related. 13) R. W. Sharp, Differential Geometry: Cartan's Generalization of Klein's Erlangen Program, Springer-Verlag, New York, 1997. This is the main textbook on Cartan geometry. But, it's probably best to read a few chapters of Derek's paper first, since the key ideas are presented more intuitively. My friend the geometer and analyst Rafe Mazzeo, whom I recently saw at Stanford, told me that Cartan geometry was all the rage these days. I'm embarrassed to say I hadn't know this! I think the kinds of Cartan geometry being intensively studied are related to conformal geometry, CR structures and stuff like that... Merry Christmas! Quote of the Week: "The Universe has as many different centers as there are living beings in it." - Alexander Solzhenitsyn http://www.shipov.com In Einstein's 1915 GR prior to the introduction of the teleparallel Kibble-Shipov torsion field with the 6 anholonomic angular pre-Calabi-Yau coordinates for the orientation of the Einstein-Cartan tetrad frame mobile {e^a} http://heasarc.nasa.gov/docs/cosmic/sheets_voids.html thus: I only write about stuff that I know about or, at least, have read about in the God-am newspapers. just note that, in many instances, there really is only "one side to the story" being reported, Darfur e.g. Isn't there a better forum for your warped political perspective than a news group on Buckminster Fuller? thus: so, how many proofs of pyhtagoras' theorem, can't you comprehend?... as for Hales' proof of Kepler's C., it never actually worked, as shown in one of the popularizing books on it, I think; it's kinda hard to find any overt admission of this on Hales' website, though ... and, he *did* prove an important related theorem.... this may also apply to the fourcolorconjecture, but several simplicifications of the computerized one have been done, so ... I believe Ribet on Wiles' "proof," although I'd rather learn how Fermat did it; at least, he made no other known mistakes. still, the characterization of the Fermat primes is an open problem, arguably more important than his "last." as for the nonexistence of a proof of RH or Goldbach C., quelle ridicule! And the bugs in the accepted proofs of the fundamental theorem of algebra by Girard, D´´ thus: completely interconsistent with your theory, two, since you can, now, have "travelled back" to them, at Langley or where ever, to tell them how to do it.... I'd call Art Bell; you should not let Al Beliek and John V. Neumann try to take the credit for it, based upon the Philedelphia Experiment, which everyone knows was just to test *radar* "invisibility," if you hadn't already preempted that in your Delorean.... don't drive over all of your great-great granchildren! you were referring to Normal CIA Remote Viewing, the kind that was completely ineffective (or completely hidden from sight, of course, because there's all of this great theory to back it "up" .-) "If we knew what it was we were doing, it would not just be called research; it would be also known as The Rectal Display Unit!" --J.Sarfatti thus: Harry Potter-affiliated stuff, in general -- like both Iraq wars). this just in: yesterday's (Tues,. Nov.15) *UCLA Daily Bruin* finally noted that darfur is entirely Muslim, though downplaying it AMAP. thus: Dick Cheeny, Don Rumsfeld and Osama bin Latin form a mission to Darfur, to prevent a war instead of to start one: if Darfur is "100% Muslim," then what's really going on, there? is it just aother British Quag for USA soldiers to get bogged into, with Iran, Iraq, Afghanistan et al ad vomitorium, under auspices of the UN and NATO? why won't the Bruin publish the fact of Islam on the ground, therein? thus: Why doesn't the [UCLA Daily] Bruin report that Darfur's populace is "100%" Muslim, according to the DAC's sponsor, Terry Saunders?... "99%" was the figure given by Brian Steidle, when I finally found him at the Hammer, after everyone else had left (he, his friend & I were the very last to leave!)... What could it possibly mean? --The Other Side (if it exists) |
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Aluminium Holocene Holodeck Zoroaster wrote:
11) Derek Wise, MacDowell-Mansouri gravity and Cartan geometry, available as gr-qc/0611154. Elie Cartan is one of the most influential of 20th-century geometers. At one point he had an intense correspondence with Einstein on general relativity. His "Cartan geometry" idea is an approach to the concept of parallel transport that predates the widely used Ehresmann approach (connections on principal bundles). It simultaneously generalizes Riemannian geometry and Klein's Erlangen program (see "week213"), in which geometries are described by their symmetry groups: EUCLIDEAN GEOMETRY -------------- KLEIN GEOMETRY | | | | | | | | v v RIEMANNIAN GEOMETRY -------------- CARTAN GEOMETRY Given all this, it's somewhat surprising how few physicists know about Cartan geometry! That's probably because Cartan's connection can be also phrased in terms of an Ehresmann connection on an adjusted bundle. So at the end of the day it's just a question of preference for a type of "packaging". -- Jan Bielawski |
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![]() JanPB wrote: Aluminium Holocene Holodeck Zoroaster wrote: 11) Derek Wise, MacDowell-Mansouri gravity and Cartan geometry, available as gr-qc/0611154. Elie Cartan is one of the most influential of 20th-century geometers. At one point he had an intense correspondence with Einstein on general relativity. His "Cartan geometry" idea is an approach to the concept of parallel transport that predates the widely used Ehresmann approach (connections on principal bundles). It simultaneously generalizes Riemannian geometry and Klein's Erlangen program (see "week213"), in which geometries are described by their symmetry groups: EUCLIDEAN GEOMETRY -------------- KLEIN GEOMETRY | | | | | | | | v v RIEMANNIAN GEOMETRY -------------- CARTAN GEOMETRY Given all this, it's somewhat surprising how few physicists know about Cartan geometry! That's probably because Cartan's connection can be also phrased in terms of an Ehresmann connection on an adjusted bundle. So at the end of the day it's just a question of preference for a type of "packaging". Jan Bielawski OK, Jan, using that so-called "packaging", can you provide a means to relate how EM and gravitation are unified at some level, for example, I find that gravitation is a 2nd order effect of EM caused by matter, just as magnetism is a 2nd order effect of electrostatic's relatively to moving frame. Regards Ken S. Tucker |
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![]() "Ken S. Tucker" wrote in message ps.com... Hi Ken Please e-mail me at peter102560NOSPAM at comcast DOT com. I once again lost your e-mail address due to the need to wipe my system clean and reinstall windows xp from scratch. This time I'll put your e-mail address in my hotmail contacts list. Thanks. Best regards Pete |
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![]() Pmb wrote: "Ken S. Tucker" wrote in message ps.com... Hi Ken Please e-mail me at peter102560NOSPAM at comcast DOT com. I once again lost your e-mail address due to the need to wipe my system clean and reinstall windows xp from scratch. This time I'll put your e-mail address in my hotmail contacts list. Thanks. Best regards Pete Hi Pete, I've been slacking my course studies lately, we lost a bit contact on our mutual study of Shultz sp mainly cuz of holidays etc. and the chemo baby. My email is dynamics (at) uniserve.com Best Regards Ken |
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![]() "Ken S. Tucker" wrote in message ups.com... Pmb wrote: "Ken S. Tucker" wrote in message ps.com... Hi Ken Please e-mail me at peter102560NOSPAM at comcast DOT com. I once again lost your e-mail address due to the need to wipe my system clean and reinstall windows xp from scratch. This time I'll put your e-mail address in my hotmail contacts list. Thanks. Best regards Pete Hi Pete, I've been slacking my course studies lately, we lost a bit contact on our mutual study of Shultz sp mainly cuz of holidays etc. and the chemo baby. My email is dynamics (at) uniserve.com Best Regards Ken Do you still want to do Schutz? What else are you studying? Pete |
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Pmb wrote:
"Ken S. Tucker" wrote in message ps.com... Hi Ken Please e-mail me at peter102560NOSPAM at comcast DOT com. I once again lost your e-mail address due to the need to wipe my system clean and reinstall windows xp from scratch. This time I'll put your e-mail address in my hotmail contacts list. Thanks. Just switch to Linux and forget Hotmail. I haven't seen a virus since 1999 and this without any antivirus protection besides the standard Linux firewall settings. -- Jan Bielawski |
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On 2006-12-28 02:00:03 +0000, "JanPB" said:
Pmb wrote: "Ken S. Tucker" wrote in message ps.com... Hi Ken Please e-mail me at peter102560NOSPAM at comcast DOT com. I once again lost your e-mail address due to the need to wipe my system clean and reinstall windows xp from scratch. This time I'll put your e-mail address in my hotmail contacts list. Thanks. Just switch to Linux and forget Hotmail. I haven't seen a virus since 1999 and this without any antivirus protection besides the standard Linux firewall settings. Or do what I did and buy a Mac ;-) Admittedly also behind my own linux firewall ;-) -- For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring. Carl Sagan -- Posted via a free Usenet account from http://www.teranews.com |
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