I decided to post a brainstorm on an unsolved problem in theoretical physics just to get it out there. This is probably not particularly interesting to most of my readers- pardon the detour. Back to your regularly scheduled content shortly.
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An analogical approach to explaining Dark Energy, with a suggested formalization:
Dark Energy, or the mystery force causing the accelerated expansion of the universe, is one of the prime mysteries of modern physics. The approach I suggest here, which I believe to be novel, is essentially to model spacetime as imperfectly compressible (contrary to the common implicit assumption of perfect compressibility) and identify Dark Energy as the natural, emergent 'pushback' connected with gravity's compression of spacetime.
For example, if we take spacetime to be like a balloon, the gravitational effects from aggregated clumps of matter (stars, galaxies, black holes, etc) are like fingers pushing into the balloon. It's natural for the balloon to bulge where it's not being compressed.
If spacetime is perfectly incompressible wrt gravity, we could expect a special-case universe composed of 0% energy, 100% homogeneously distributed matter to neither contract nor expand (contrary to the current prediction of contraction due to gravity), much like how a balloon filled with incompressible gas pushed equally from all sides would stay in equilibrium. Once matter starts to 'clump up', however (and it invariably would due to quantum effects), the universe would start to expand. I haven't run the numbers, but it would appear such expansion might become an accelerating positive-feedback cycle.
The timeline of massive expansions due to Dark Energy seems to correlate with what we can guess about major thresholds in the de-homogenization of matter distribution. We would expect a massive initial de-homogenization right after the Big Bang due to quantum effects, then another when particles are able to form, another when large-scale matter structures are able to form, and another as matter organizes into very large scale structures such as galaxies, clusters, and superclusters.
I would formalize this as follows: within any specific range of times, Dark Energy should be equal to:
Gr(a)*S(a) - Gr(h)*S(h)
Where
Gr(a) is the actual number of gravitons exchanged in the universe;
Gr(h) is the hypothetical number of gravitons which would be exchanged in a universe of the current size if matter and energy were distributed homogeneously (necessarily equal to or lesser than Gr(a));
S(a) is the scaling factor of how much the average graviton bends spacetime in the current universe;
S(h) is the scaling factor of how much the average graviton would bend spacetime in a hypothetical universe of the current size but where matter and energy were homogeneously distributed-- presumably differing from S(a) due to differences in average graviton longevity.
(An alternate geometrical formalization might involve trying to quantify Dark Energy as a buoyant effect on spacetime equal to the total amount of spacetime 'displaced' by the gravitational imprint of matter+dark matter+energy.)
Obviously this formalization needs a lot more work on a number of fronts. Specifically, we don't know enough about the mechanics of gravitons to speak with much confidence on the difference between S(a) and S(h), and it's unclear how this force would make itself felt (a new carrier particle? A non-localizable property of spacetime? A MOND-like modification of gravity? If it's a carrier particle might there be a lag effect?). I'll admit it's rough. But I think the core approach is relatively clear.
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5.16.2008
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