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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: 0) by Anonymous Coward on Saturday October 06 2018, @01:23AM (1 child)
No what he means is that if gravity is passing through dimensions that EM is not, then it would lose amplitude faster than EM.
Since EM is adequately described by models containing 3+1 dimensions, it is assumed that if EM and Gravity were passing through a different number of dimensions then there would be a greater dropoff in the higher dimensional force relative to the lower dimensional force.
What was found was that gravity and EM both drop off at the same rate, ergo they share n-dimensionality and since EM is known to be 4 dimensional, then gravity must be too.
One of the major explanations thus far for gravity's weakness has been that perhaps it was as strong as the other forces, but most of that force was leaking into a higher dimension.
This is now disproven to a high degree of certainty
(Score: 0) by Anonymous Coward on Saturday October 06 2018, @04:41PM
Pretty sure there is no spacetime in quantum mechanics.