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Supernovas Act as Time Machines To Illuminate Dark Energy (Or Do They?)
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A few years back, there were several stories about a proposal based on String Theory and a Multiverse, made by Georgi Dvali - of NYU. Dvali's theory is that, if gravitons are closed-loop strings, and not bound to a universe (like every other particle), they can be drawn from one universe by a more powerful attractor in a parallel universe. According to this idea, as universes expand, their mass becomes less and less able to prevent graviton leakage, and the rate of expansion increases:
This repulsive, unknown force is believed to make up more than 70 percent of the mass-energy budget of the universe.
But the existence of dark energy is far from proven, and some researchers believe they and their colleagues simply don't understand gravity at larger scales. The gravitational pull between any two objects becomes less with distance. But in Dvali's view, it weakens more than standard theory predicts.
Dvali would modify the theory of gravity so that the universe becomes self-accelerating, eliminating the need for dark energy.
The idea might be testable.
Gravity leakage should create minor deviations in the motion of planets and moons. Astronauts on the Apollo 11 mission installed mirrors on the lunar surface. By shooting lasers at the mirrors, a reflected beam can be monitored from Earth to measure tiny orbital fluctuations. Dvali said deviations in the moon's path around Earth might reveal whether gravity is really leaking away.
Has gravity sprung a leak? - Technology & science - Space - Space.com - msnbc.com
A lot of physicists would likely prefer it if Dvali's theory could be confirmed. It would provide verfication for SuperstringSupersymmetry Theory, plus explain the universal acceleration without finding a way to modify General Relativity.