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from the 4-dimensions-ought-to-be-enough-for-anybody dept.
Scientists have managed to constrain the possible number of dimensions of our universe to 3+1 (3 spatial and 1 time).
According to a new paper on Arxiv https://arxiv.org/abs/1801.08160
A recent merger of neutron stars that was observed in the visible spectrum, as well as with gravity waves, was used to determine that there are no extra dimensions for gravity to leak into. This reinforces our current models based on 3+1 to an extremely high degree of certainty and essentially rules out any theory that requires extra dimensions in order to function.
Quoting the paper:
The observation of GW170817 in both gravitational and electromagnetic waves provides a number of unique tests of general relativity. One question we can answer with this event is: Do large-wavelength gravitational waves and short-frequency photons experience the same number of spacetime dimensions? In models that include additional non-compact spacetime dimensions, as the gravitational waves propagate, they "leak" into the extra dimensions, leading to a reduction in the amplitude of the observed gravitational waves, and a commensurate systematic error in the inferred distance to the gravitational wave source....
The short of it was that there was absolutely no evidence for electromagnetism and gravity to be propagating through a different number of dimensions than the expected 3+1.
These are just some really cool and unexpected results; in my case I was a big supporter of brane theory until this result came out. Now, I don't know what to think. Gravity is too weak to make any sense at all. What do you think?
(Score: 2) by idiot_king on Friday October 05 2018, @10:00PM (5 children)
Not a physics person, never understood why "Gravity is weak" when it holds together galaxies as opposed to the other fundamental forces which do not.
(Score: 5, Informative) by bob_super on Friday October 05 2018, @10:08PM
Gravity is weak because I can fight the Earth's pull on an object and win. With a tiny magnet.
But gravity is weak in the same sense that Evolution is slow. Doesn't matter what your local disturbance is, both win at the end.
(Score: 5, Informative) by BsAtHome on Friday October 05 2018, @10:12PM
"weak" is relative to the magnitude of the electro-magnetic interaction. However, EM interactions are neutral in the sum (positive and negative interaction cancel). That is apparently not the case with gravity, which has only one sign (positive). Therefore, gravity may stretch its hold up to infinity.
(Score: 4, Informative) by insanumingenium on Friday October 05 2018, @11:58PM (1 child)
(Score: 2) by Snotnose on Saturday October 06 2018, @02:22AM
That looks like a helluva website, Thanks!
When the dust settled America realized it was saved by a porn star.
(Score: 0) by Anonymous Coward on Saturday October 06 2018, @12:01AM