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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.
Slashdot posting an article on fundamental physics? Must be a slow news day.
OP here. Obviously, my submission had the bad luck of making it to the Slashdot front page simultaneously with the US presidential elections and their unexpected outcome. Yet I am appalled, truly appalled and disgusted, at what ACs have posted here (see above).
It is now clear to me that after many, many years there is nothing anymore for me on Slashdot. This is it. The level had gone down already for years. The repeated and increasingly vocal racism and vulgarity, the inanity, the name-calling, the bigotry - it had already been putting me off for a long time. Yet I had hoped that, at least for such momentous scientific news as Verlinde's theory, there could have been a discussion worthy of that name.
Slashdot's latest acquirer has done a prolly valiant job to try and turn things around, an effort before which I flourish my hat. It is clear to me, however, that it was too little and too late. I'm leaving slashdot. I will keep reading submissions as an anonymous reader, and that's it. So long, Slashdot !
Religous speak to God. Insane are spoken to by God. When all shut up, one can finally hear Shostakovich in peace
Jokes apart, it seems to me like you can derive from it everything you whish, just by messing opportunely with the hypothesis.
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
Oh sure...
It can explain "Dark Matter"; but can it explain other TV series, like "Killjoys", and all the time travel series?
I must confess I'm completely out of my depth here (and not for the first time), but considering that gravity is now considered a dynamic process, would this open the way for anti-gravity devices?
If so within a week we went from nothing to a completely plausible sci-fi universe.. Reactionless drives, anti-gravity... FUN
It seems it's turtles all the way down. I could follow this gravity saga up to general relativity where it becomes slightly blurred.
Even though I'm excited about new developments in physics, I'm kind of sad it's getting more and more incomprehensible. I just can't grasp strings & holograms at any level. The same goes for modern developments in mathematics.
"Blah blah blah." - [citation needed]
how there is no other explanation for the velocity discrepancies than dark matter.
Whoever said that? I've read long ago that people were looking for refinements or new theories of gravity to explain the discrepancy.
"Dark matter" is not even a "thing" - it is a placeholder for something unknown. A simple hypothesis. Could you say it is a bit like the cosmological constant?
So flipping the paper over, if dark matter is real, quantum entanglement isn't.
So the experimental proof would be to go find the missing matter and disprove entanglement!
Gravity in general relativity is not a fundamental force. It is an apparent force you experience because you chose an inappropriate frame of reference (e. g. you're not free-falling). Much like rotational forces.
I know what you're thinking, "Yeah, sure you did." In this one particular case, I did.
Somewhere in my notes for something I'm working on I posed the question, "Why is it that gravity is a force unto itself? Why can't gravity be the result of the interaction of the other forces?"
I raised that question because no one had detected a gravity wave. Until this year (Feb 11, 2016). So now the question becomes, if gravity waves were detected, how does this discovery affect this paper? Wouldn't that "disprove" the idea and lead to gravity being the force we always thought it was?
We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
And I'm 99% sure that it was here on /. that I read it.
Most importantly, Verlinde's paper has as a consequence that dark matter, nemesis of many an astronomer, is nothing more than an illusion.
This has been something I've been asking about for years with no good answer. Namely, what evidence exists to prove that so-called "dark matter" is actually matter rather than a defect in our mathematical model of gravity? Why is this not similar to how Einstein found a better model (relativity) for the phenomena first described by Newton? We're going through all sorts of contortions to try to prove that some mysterious "matter" must be there even though we have no idea what it could possibly be, have no direct observations, and our only evidence for it is inferred from our current models of gravity which we know to be incomplete since they do not work with quantum mechanics. While it certainly might be some form of exotic matter it seems at least equally probable that the answer might instead be that a better model is needed and that our current model is deficient in some way.
Stick around for a minute and explain how this gravity-modification strategy for getting rid of dark matter doesn't suffer from the exact same problems as MOND.
Your post has a sort of reverse-l'esprit de l'escalier feeling to it, like if you had waited an hour or day you would not have written it. Try not to consider yourself too tightly bound by any vows of pique.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
My money is still on gravity being the result of particle wind (maybe neutrinos, maybe some other such). A body resting in isolation is bombarded in all directions and suffers "no gravitational attraction". Place a massive body near by, which blocks the wind in one direction and you see "gravitational attraction" in that direction. Several physicists have tried this angle and made progress but ultimately failed to make it work. However, it still seems the most economical and logically consistent explanation.
Sorry, but this doesn't explain actual observations! It may be that some sort of modified gravity is a partial answer, but the mass distribution in galaxy clusters, and possibly other places as well, simply isn't explained by a non-physical effect.
"Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
No it is more than just a "thing" - we know that it behaves like matter in many ways thus the name.
I think making it easier to make throwaway accounts might be a better solution than posting anonymously.
I see the Big Bang as a one-zero event during which something that wasn't comes into existence. That one thing was just "space." So I see the universe as composed of different densities of space coming into existence according to when during the Big Bang they came into existence. "Matter" then is just a very dense form of space. What we call "space" is just the "lightest" form of space. But there may be simply a "denser" form of space that came earlier in the Big Bang. Gravity being a property of space. And when a nuclear reaction takes place, what is actually happening is the conversion of a denser form of space (matter) into its less dense form and expanding, the analog being what happens in a conventional explosive when it detonates. The movement that is produced by this being called "energy." So, Dark Matter may be nothing more than the gravitational effect of dense space and there is no space of the density to be called matter in its conventional understanding causing the gravitational effects they are trying to explain. Perhaps our universe is nothing more than the result of a splitting "ATOM." I see the universe as a cauldron of condensing and expanding space. (E=MC^2 may actually be Space = MC^2)
E Proelio Veritas.
I remember MOND theory was debunked as dark matter was proven to be a kind of matter and not an error in Gratitation theory.
Just because MOND isn't the right answer it doesn't follow that the problem cannot be with the model. All that proves is that one specific model doesn't work. And the problems with MOND don't appear to be so much related to dark matter but rather to an inability to predict behavior of galaxy clusters that we can observe. We have direct evidence or workable model for what dark matter is even if we make the (reasonable) assumption that it is indeed some form of matter. It MIGHT be matter but nobody seems to be able to point to any observation or theory that proves that it must be matter while ruling out all other explanations.
I'm perfectly willing to accept that it might be some form of matter we've never observed before but it seems just as likely to me that our model could be wrong in some way. In actual fact we know our models must be incomplete since we haven't yet reconciled the two most important physics models we have in relativity and quantum mechanics. If our understanding of gravity breaks down on a very small scale it's not unreasonable to think we might not fully understand how it works on a very large scale too. I'm not saying out model must be wrong but it seems to me that presuming dark matter is actually matter seems a touch premature just yet. Especially since nobody seems to be able to explain in layman's terms why exotic matter is the only possible answer to the question "what is dark matter?"
No it is more than just a "thing" - we know that it behaves like matter in many ways thus the name.
And caloric appears to account for the flow of heat--and a depletion of phlogiston is why burning wood results in ashes--and lumnifierous ether is the medium of for the propagation of light waves in interstellar space.
I was always betting that dark matter would turn about to be yet another fictitous fluid with contradictory properties.
It's less that the earth sucks as much as space blows.
File under 'M' for 'Manic ranting'
When physics couldn't explain what existed beyond earth they invented ether. When physics couldn't explain the expansion of the universe they invented dark-matter.
Same idea and will probably be proved equally laughable one day once we have a better understanding of the universe; but that's science, you come up with a theory until you gain a better understanding and build upon it.
"That's the way to do it" - Punch
Forbes (Warning: source is anti-adblock and WILL serve ads with MALWARE):
TFTFY.
Also, Forbes, used to be a business magazine. Not really a authoritative source on science an technology.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
So , the idea is that after all gravity can be an entropic force? I thought there was a no-go theorem for this. In any case, the microscopic mechanism could be quantized?
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)
That's okay. Gravity believes in you, and it wants a hug.
I too get sick of endless troll wars but can quickly sift through it.
Thanks vikingpower for the submit to the interesting paper.
As this kind of science is above my job description does this theoretical treatment amend itself to testable confirmation?
Isn't Newtonian gravity wrong though? It failed to predict the precession of the orbit of Mercury. Correct me if I'm wrong but isn't it just basically the inverse square law, which applies to radiant phenomena (like the intensity of light radiating from a point source.)
So, if this guy 'derived Newtonian Gravity' from his theory, then his theory is wrong too, isn't it?
What am I missing here?
In theory, theory and practice are the same; in practice they're different. (Yogi Berra & A. Einstein)
From your summary, it sounds like the paper attempts to explain galactic rotation curves. Does it have anything to say about gravitational lensing where there's no apparent matter?
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
And caloric appears to account for the flow of heat--and a depletion of phlogiston is why burning wood results in ashes--and lumnifierous ether is the medium of for the propagation of light waves in interstellar space.
So dark matter is the best theory known given the data we have, and if it does get disproved the process of doing so will point us toward better theories? Sounds like science at its best.
But somehow I think you're just looking for a future 'told you so'.
Dark matter might just be the byproduct of gravity's troubled youth? Perhaps this is just this Universe's way of expunging a bad mistake? A Universe redacted, as it were...
PlaynBass
Something like that. Or the Speed of Time. But anyway. Whatever.
That seems to be at least as precise as Charles Darwin described evolution, how is that not a theory?