- #1
S.Daedalus
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No, that wasn't a lapse into lolcatese -- ur theory was CF von Weizsäcker's attempt to explain the apparent unity of physics by basing it on the abstract quantum theory of what he called ur-alternatives -- which are essentially equivalent to the more modern notion of qubits. Starting from general philosophical considerations on abstract information, he (and his collaborators) attempted to essentially reconstruct physics from first principles, reasoning that two-level quantum systems are the most fundamental ones in quantum theory, and that any quantum system can be embedded in the tensor product of such two level systems.
The idea has some interesting implications and applications -- for instance, three-dimensional position space is derived from the urs' symmetry group, there are arguments for deriving Bekenstein-Hawking entropy and a positive cosmological constant of roughly the right order, special relativity, particles, etc. Somewhat more weirdly, ur theory appears to predict the number of nucleons in the universe ([tex]10^80[/tex], which I'm told is in line with current observation), as well as the baryon/photon ratio.
However, work on this theory seems to be mainly concentrated on a small 'in-group', and today, almost nobody seems to pursue this line of research anymore; add to that the impression that I have that some of the arguments are a bit on the hand-wavy side, and I wonder if there's actually anything to it, or if it's just one more chimera conjured up by bold assumptions and great hopes...
If you're interested, but unfamiliar with the subject, you can find a paper giving a short introduction to ur theory here: http://arxiv.org/abs/quant-ph/9611048; I'd appreciate hearing anybody's reactions/opinions, and perhaps, if anybody's familiar with it, a bit on how the theory has been/is viewed in the larger research community.
The idea has some interesting implications and applications -- for instance, three-dimensional position space is derived from the urs' symmetry group, there are arguments for deriving Bekenstein-Hawking entropy and a positive cosmological constant of roughly the right order, special relativity, particles, etc. Somewhat more weirdly, ur theory appears to predict the number of nucleons in the universe ([tex]10^80[/tex], which I'm told is in line with current observation), as well as the baryon/photon ratio.
However, work on this theory seems to be mainly concentrated on a small 'in-group', and today, almost nobody seems to pursue this line of research anymore; add to that the impression that I have that some of the arguments are a bit on the hand-wavy side, and I wonder if there's actually anything to it, or if it's just one more chimera conjured up by bold assumptions and great hopes...
If you're interested, but unfamiliar with the subject, you can find a paper giving a short introduction to ur theory here: http://arxiv.org/abs/quant-ph/9611048; I'd appreciate hearing anybody's reactions/opinions, and perhaps, if anybody's familiar with it, a bit on how the theory has been/is viewed in the larger research community.
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