Urs Schreiber
Shared publicly12:46 PM
Geometrodynamics in the 19th Century. In models of particle physics such as the G2-MSSM [1] everything is spacetime. These models are pure KK-compactifications [2] of 11d supergravity [3] and all forces and matter inside them are incarnations of the dynamics of spacetime. (Of super-spacetime, yes, but supergeometry is geometry just as well, it's as cohesive as plain differential geometry [4], in fact more so.) So these models may be thought to realize Wheeler's "geometrodynamics" [5] and are maybe even "more pure" gravity than Wheeler had ever envisioned.
While the unity of space-time is common place in our age, a century after Poincare and Einstein, even half a century after Wheeler the perspective that this unity is matter and forces is something not nearly as widely considered. There is one Gordon Kane who keeps highlighting out how good these models are phenomenologically [6], but, due to the state of the field (...), sober discussion of this point seems difficult at this time.
There was however one guy, who already in the first half of the 19th century claimed that this is self-evident:
"The disappearance and regeneration of space in time and of time in space is motion, and the unity of both is embodied as matter."
I have paragraphased and shortened the original just a little, only to make Googling for it harder.
[1] http://ncatlab.org/nlab/show/G2-MSSM
[2] http://ncatlab.org/nlab/show/KK-compactification
[3] http://ncatlab.org/nlab/show/11-dimensional+supergravity
[4] http://ncatlab.org/nlab/show/smooth+super+infinity-groupoid
[5] http://ncatlab.org/nlab/show/geometrodynamics
[6] http://arxiv.org/abs/1112.1059
While the unity of space-time is common place in our age, a century after Poincare and Einstein, even half a century after Wheeler the perspective that this unity is matter and forces is something not nearly as widely considered. There is one Gordon Kane who keeps highlighting out how good these models are phenomenologically [6], but, due to the state of the field (...), sober discussion of this point seems difficult at this time.
There was however one guy, who already in the first half of the 19th century claimed that this is self-evident:
"The disappearance and regeneration of space in time and of time in space is motion, and the unity of both is embodied as matter."
I have paragraphased and shortened the original just a little, only to make Googling for it harder.
[1] http://ncatlab.org/nlab/show/G2-MSSM
[2] http://ncatlab.org/nlab/show/KK-compactification
[3] http://ncatlab.org/nlab/show/11-dimensional+supergravity
[4] http://ncatlab.org/nlab/show/smooth+super+infinity-groupoid
[5] http://ncatlab.org/nlab/show/geometrodynamics
[6] http://arxiv.org/abs/1112.1059
'via Blog this' The Honourable Schoolboy
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