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New Theory of Gravity Might Explain Dark Matter (phys.org)
vikingpower writes: Dutch prodigy and Amsterdam University Professor Erik Verlinde published a paper on arXiv yesterday, November 7, titled "Emergent Gravity and the Dark Universe." In the paper, Verlinde derives gravity from the so-called Holographic Principle, which -- simply put -- states that gravity emerges from the interplay between and entropy re-arrangement of sub-atomic "strings" that live in a negatively curved spacetime. At that level [...] spacetime and gravity are emergent from an underlying microscopic description in which they have no a priori meaning." Most importantly, Verlinde's paper has as a consequence that dark matter, nemesis of many an astronomer, is nothing more than an illusion. Verlinde, who was awarded the Dutch national Spinoza science prize in the recent past, already completed the tour de force of deriving Newtonian gravity from the same principles in a 2010 paper, also on arXiv. We are probably looking at Nobel-prize material here, as Verlinde is acknowledged by his peers to "go one better than Einstein's General Theory of Relativity." Slashdot reader turkeydance adds from a report via Forbes (Warning: source may be paywalled): As dark matter continues to vex astronomers, new solutions to the dark matter question are proposed. Most focus on pinning down the form of dark matter, while others propose modifying gravity to account for the effect. But a third proposal is simply to remove gravity from the equation. What if the effects of gravity aren't due to some fundamental force, but are rather an emergent effect due to other fundamental interactions? A new paper proposes just that, and if correct it could also explain the effects of dark matter.
It's strange that Verlinde uses 'elastic' in the abstract.
"The emergent laws of gravity contain an additional dark gravitational
force describing the elastic response due to the entropy displacement."
I think space can be thought of like some kind of elastic material. At first, space begins to regain its original form (where there is no matter) quickly from the center of gravitation. However, as we go further and further from the center this process slows down.
The end result is that space will be more curved than we expect at large distances.
Government cannot make man richer, but it can make him poorer. - Ludwig von Mises
No it is more than just a "thing" - we know that it behaves like matter in many ways thus the name.
Except maybe soon we'll know it's not a "thing" after all, if this guy is right. And he seems to have quite a bit of support from colleagues all over the world.
I skimmed the actual paper, probably misunderstood 90% of it, but here's what I think I understood (feel free to correct me, really, I mean it, I would like to know the real story)
- The universe is full of tiny vibrating strings
- Certain particular vibration modes are what we perceive as "particles". Those have less entropy, therefore the presence of mass implies lower local entropy
- Lower entropy somehow causes gravity as some kind of emergent side-effect. Something similar to the theory of elasticity.
- On smallish scales (say, the solar system) the resulting "force" corresponds perfectly to our old formulas for gravity
- On larger scales, entropy of a volume is limited by surface area. Something like the holographic principle, but not quite the same because the entropy is stored all over the volume and not just on its surface. Lots of strings really being the same string due to entanglement? Or something like that.
- This somehow magnifies the effect of gravity for large masses over large distances (say, the scale of a galaxy). Not sure why: maybe the same reduction in entropy has a larger than expected relative effect because of the lower than expected entropy?
- There was also something about large spaces relaxing more slowly, but I lost the plot there. Although it did seem important.
Anyway, if this theory matches observations without introducing new funky constants, dark matter and dark energy could just be totally unnecessary concepts.
(Posting as AC after having modded a whole bunch of off-topic Trump idiots into oblivion)