Study finds flaw in emergent gravity

August 10, 2018 by Lisa Zyga, Phys.org feature
Study finds flaw in emergent gravity
Illustration of a three-dimensional hypersurface. Credit: Wang and Braunstein. Published in Nature Communications

In recent years, some physicists have been investigating the possibility that gravity is not actually a fundamental force, but rather an emergent phenomenon that arises from the collective motion of small bits of information encoded on spacetime surfaces called holographic screens. The theory, called emergent gravity, hinges on the existence of a close connection between gravity and thermodynamics.

Emergent gravity has received its share of criticism, however, and a new paper adds to this by showing that the holographic screen surfaces described by the theory do not actually behave thermodynamically, undermining a key assumption of the theory.

Zhi-Wei Wang, a physicist at Jilin University in Changchun, China, and Samuel L. Braunstein, a professor of quantum computational science at the University of York in the UK, have published their paper on non-thermodynamic surfaces in a recent issue of Nature Communications.

"Emergent gravity has very strong claims: that it can explain things like dark matter and dark energy, but also reproduce the decades of work coming out of regular general relativity," Wang told Phys.org. "That last claim is now knocked on its head by our work, so emergent gravity proponents will have their work cut out for themselves in showing consistency with the huge canon of observational results. We've set them back, not necessarily knocked them out."

In the cosmological context, surfaces refer generally to any two-dimensional area in spacetime. Some of these surfaces, such as the horizons of black holes and other objects, are confirmed to be thermodynamic. For black hole horizons, this has been known since the 1970s, since the very laws that define black hole mechanics are directly analogous to the laws of thermodynamics. This means that black hole horizons obey thermodynamic principles such as and having a positive temperature and entropy.

More recently, surfaces that are not horizons have been conjectured to obey the laws of thermodynamics, with the holographic screens in the emergent gravity theory being one example. However, so far these conjectures have not been fully justified.

In the new paper, the scientists tested whether different kinds of surfaces obey an analogue of the first law of thermodynamics, which is a special form of energy conservation. Their results reveal that, while surfaces near black holes (called stretched horizons) do obey the first law, ordinary surfaces—including holographic screens—generally do not. The only exception is that ordinary surfaces that are spherically symmetric do obey the first law.

As the scientists explain, the finding that stretched horizons obey the first law is not surprising, since these surfaces inherit much of their behavior from the nearby horizons. Still, the scientists caution that the results do not necessarily imply that stretched horizons obey all of the laws of thermodynamics. On the other hand, the finding that ordinary surfaces do not obey the first law is more unexpected, especially as it is one of the key assumptions of emergent gravity. Going forward, researchers will work to understand what this means for the future of emergent gravity, as well as explore other possible implications.

"We spent a large amount of time working out how to reproduce the original results for from the 1970s," Braunstein said. "Although the methods from the 1970s were extremely tedious to replicate in detail, we found them very powerful and are thinking now about whether there is any way to generalize these results to other scenarios. Also, we think that our formula for the deviation away from the first law as one moves away from horizons will have important implications for quantum ."

Explore further: Escaping gravity's clutches: The black hole breakout

More information: Zhi-Wei Wang and Samuel L. Braunstein. "Surfaces away from horizons are not thermodynamic." Nature Communications. DOI: 10.1038/s41467-018-05433-9

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novasp9
2.7 / 5 (10) Aug 10, 2018
"Holographic screens"? Do they sell them at Walmarts, in the pseudoscience section?
fthompson495
1 / 5 (14) Aug 10, 2018
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

There is evidence of the supersolid dark matter every time a double-slit experiment is performed, as it is the supersolid dark matter that waves.

Supersolid dark matter ripples when galaxy clusters collide and waves in a double-slit experiment, relating general relativity and quantum mechanics.

grandpa
1.5 / 5 (4) Aug 10, 2018
So the article says only symmetric spheres could have emergent gravity. Well I guess that means that everything is made of symmetric spheres.
joel in oakland
4.5 / 5 (4) Aug 10, 2018
@ fth495
interesting conjecture - hope you publish the math (or whatever) that led you to this idea.
Claudius
3 / 5 (2) Aug 10, 2018
I wonder if anyone has yet considered dark matter could be a manifestation of the multiverse proposed by David Deutsch,etc.
Hyperfuzzy
1 / 5 (6) Aug 10, 2018
+/-Charge Exists; therefore any other particle or force of nature is derivative. Since the Center of each E Field is unique, ...
Hyperfuzzy
1 / 5 (5) Aug 10, 2018
Logic! Anyway, we know dat since Coulomb! Add Maxwell, update speed relative to the center; but the center is moving ... yeah, so
Hyperfuzzy
1 / 5 (5) Aug 10, 2018
Gravity the DC Field & charges always comply, If only 4 charge or superimposed centers; Like charges further apart than unlike therefore Gravity; better if one sees what each charge must see, wither a control field or nature, the superimposed field appears as a Charge at a Vector point. Anyway set c=1; then dimension = lambda, perspective; each point has a set of attributes; you may ... save, reuse
Hyperfuzzy
1 / 5 (5) Aug 10, 2018
Notice: Stationary State 0; Chosen state, simply drop and stabilize, ... the elements or 2N stabile combos, unstable, useful, controllable, assemble, ...
What can a computer see and control, "to infinity and beyond!"
Whart1984
Aug 10, 2018
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Hyperfuzzy
1 / 5 (4) Aug 10, 2018
Since lambda is your dimension it is also a scale; you'll see how it easily builds bottom to top; the real info is the bottom; like 2 like an 1 unlike at a point; so forth. like the field the centers are also transparent; everything else update; Systematically create clusters or study nature and
Whart1984
Aug 10, 2018
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Hyperfuzzy
1 / 5 (4) Aug 10, 2018
BTW There were also attempts https://phys.org/...tml,...)

https://en.wikipe...%27s_law
Do you see the error in fundamental constants?
Whart1984
Aug 10, 2018
This comment has been removed by a moderator.
howhot3
1.7 / 5 (3) Aug 10, 2018
Interesting article. I like the Emergent Gravity theory for explaining the two mysteries of modern cosmology, the apparent missing mass of spinning galaxies and the acceleration of the expansion of the Universe. Two very difficult problems that are linked in Emergent Gravity. IMHO, gravity can be quantum and the gravity of a particle is not point like, but based on PSI, the quantum probability of position in a partition of space.

Now ponder that last sentence a few moments and the reply back why an apparent dark matter doesn't just emerge from quantum gravity. It has to,
tallenglish
1 / 5 (3) Aug 10, 2018
One thing that bugs me - many assume "0" stands for nothing, i.e. it is some hard limit. Rather than 0 being the centre of everything, i.e. there is just as much below it as there is above it.

That goes for space as well as time, dark matter is just mass but on the bottom side, both make gravity wells from their own perspective bet repel each other. Dark matter is then the missing anti-matter from the big bang dark energy is the stuff that would be imaginary number equivilent to matter - trying to compress dark matter and expand matter.

By assuming time is only positive and real - we are ignoring 75% of the posabilities out there, and if dark matter creates gravity hills it may actually be masking some gravity from mass and ratios may well be closer to 25%/25%/50% for Mass, Dark Matter, Dark Energy - all made of the same stuff, just moving in different directions.

Simple answer is usually correct, complex ones are because someone has a huge ego.
tallenglish
1 / 5 (3) Aug 10, 2018
Think of the universe having 4 phases - +real (+sine, Light/Mass), +imaginary (+cosine, +DE), -real (-sine, DM), -imaginary (-cosine, -DE). -DE would always be pushing us from behind, +DE would always be pulling us from the front. Galaxies, stars and everything else are just turbulence - exactly the same as tornados being spawned from a hurricane, specifically on the front right side - I liken that side to being the universe we can see. +DE could well be whats beyond the event horizon of a black hole. -DE is what compresses light into mass - aka likely candidate for higgs field as it wouldn't have spin from our perspective.

No need for a big bang then as the universe is eternal and inherently circular/spherical - but it is rotating - but it does assume for 12 spacial dimensions to 1 complex temporal dimension per universe and thats just for 3D+1T, who's to say there isn't infinite dimensions for space as well as time.
Shootist
3.8 / 5 (5) Aug 10, 2018
I thought the science was settled, "gravity" is not a force

emergent phenomenon that arises from the collective motion of small bits of information encoded on spacetime surfaces called holographic screens
In my experience, if somethings in science sounds like abstract nonsense (https://imgs.xkcd...ory.png) - then it probably is. Collective motion of particles and emergence has the entropic gravity common with dense aether model - but emergence isn't utilized in it in any way: it's just a void slogan. And holographics projections have no utilization in dense aether model at all. Occam's razor is actually a good clue of validity of theories.


uh, dunce ether model has no utilization what-so-ever.
Surveillance_Egg_Unit
2 / 5 (8) Aug 10, 2018
@Shootist
Gravity was NEVER a FORCE. It is a reaction to an action, whatever the initial action is/may be - but on the precondition of the presence of Mass. It also has nothing to do with Spacetime, whatever that is. Climb a ladder to the roof and jump off. That event is a good example of Gravity as a Reaction to an Action.

"Scientists" are in the habit of finding ways to turn the simplified science into a grossly discreditable bit of mincemeat with almost unintelligible definitions that actually harm the Truth.

I also have my own hypothesis, where Black Holes are not globular entrapments for Mass/Energy, but that they are instead, in reality, DRAINS in which Mass/Energy are sucked into - similar to the water circling the drain in your kitchen sink before the water goes through the pipe due to normal gravity. My idea of a DRAIN also follows the pattern of Spiral Galaxies.
Scientists may never consider MY hypothesis since Black "Holes" it is.
Surveillance_Egg_Unit
2.5 / 5 (11) Aug 11, 2018
@ tallEnglish
Time is NOT a Dimension. Nothing can be built into, on top of, around, etc. in Time. It just flows, and out there in interstellar space, Time builds nothing. Like Dark Matter no one has ever SEEN, heard, felt, smelt or touched Time. Whereas 3 dimensional Space can be detected and interacted with.
There is no such thing as SpaceTime. It is sheer fallacy that has continued to be taught to unwary science Ph.D's.
Whart1984
Aug 11, 2018
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Whart1984
Aug 11, 2018
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Whart1984
Aug 11, 2018
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holoman
1.4 / 5 (5) Aug 11, 2018
Could anti-matter hold the key to anti-gravity ?

https://drive.goo...HxpxPJhb
Nik_2213
4 / 5 (1) Aug 11, 2018
#holoman, IIRC, there's work in progress to check anti-matter 'falls' in the usual way. Given anti-matter instantly reacts with the 'usual stuff', this is 'difficult'. Yes, any anomaly would up-end a lot of physics, but the odds are long on such. Figuring why free neutrons' half life seems so variable is another matter...
somefingguy
4.2 / 5 (5) Aug 11, 2018
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.



Do you just sit at your desk all day, wait for any new physics related article to be published, so that you can copy and paste the exact same thing over and over again? You know the definition of insanity, right?
antigoracle
3.7 / 5 (3) Aug 11, 2018
Hmmm....so, what they are claiming is that Emergent Gravity is a Fundamental Farce.

[Yes...yes..I know. I'll show myself out]
Whart1984
Aug 11, 2018
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Whart1984
Aug 11, 2018
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AllStBob
5 / 5 (6) Aug 11, 2018
Occam's razor is actually a good clue of validity of theories.

By that criteria nonsense theories with no content, like yours, must be correct.
Whart1984
Aug 12, 2018
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Whart1984
Aug 12, 2018
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Whart1984
Aug 12, 2018
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torbjorn_b_g_larsson
3 / 5 (6) Aug 12, 2018
Not really surprising since energy in general relativity is not easily conserved, c.f. the many different energy conditions that can formed. Entropy had the chance to be more fundamental, and as the paper claims the first law conservation that is more general than thermodynamics, but evidently they have problems too.

So the article says only symmetric spheres could have emergent gravity. Well I guess that means that everything is made of symmetric spheres.


Actually the paper implies symmetric sphere geometries cannot have it either, I think.

The problem for emergent gravity is that disturbances breaks it. Spheres obey the first law and can be disturbed "just so" (I assume in the radial direction) to keep obeying it. But general disturbances (such as newly verified gravitational waves) fail the law again.
torbjorn_b_g_larsson
3 / 5 (6) Aug 12, 2018
IMHO, gravity can be quantum and the gravity of a particle is not point like, but based on PSI, the quantum probability of position in a partition of space.

Now ponder that last sentence a few moments and the reply back why an apparent dark matter doesn't just emerge from quantum gravity. It has to,


No, dark matter can emerge from quantum fields (as WIMPS, say).

It is easy to quantize gravity - look up Wilzsek's Core Theory - but the problem is that the resulting standard quantum field theory is only approximative. Sure, it is more robust than all other fields since it fails first at Planck scales, and it is "rocket science" and replaces Newtonian gravity. But you need general relativity to understand how to build GPS systems, say.

Personally that makes me unsure that "quantum gravity" is the next step, since it is already taken. String theory seems more useful to recoup the inherent non-linearity and derive spacetime as well. But of course we don't know.
Whart1984
Aug 12, 2018
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Whart1984
Aug 12, 2018
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Whart1984
Aug 12, 2018
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Whart1984
Aug 12, 2018
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Hyperfuzzy
1 / 5 (3) Aug 12, 2018
Logic: Charge exists; therefore, any other particle or force is unnecessary. QED
Hyperfuzzy
2 / 5 (4) Aug 12, 2018
QM is a tool, not science. Gerry rigged to express what is measured.
savvys84
1 / 5 (4) Aug 13, 2018
all nutcases and kooks think that gravity is an emergent property
Ojorf
3.3 / 5 (7) Aug 13, 2018
I can prove you wrong savvys84.
What do you think gravity is?
savvys84
1 / 5 (4) Aug 14, 2018
I can prove you wrong savvys84.
What do you think gravity is?

Chk my papers here https://www.scrib...savvys84
and prove me wrong
Mimath224
5 / 5 (4) Aug 14, 2018
I can prove you wrong savvys84.
What do you think gravity is?

Chk my papers here https://www.scrib...savvys84
and prove me wrong

Don't agree. e.g. the 'simple pendulum. You claim time moves slower. That is not so. The longer the period the slower the PENDULUM moves. You are saying that time is the pendulum. So you need to explain that first.
granville583762
3.7 / 5 (6) Aug 14, 2018
Gravity is most definitely a Force!

Gravity attracts every particle in the direction of the gravitational source in proportion to its mass inversely proportional to the square of separation

There is no reaction on the source particle as it experiences no force - just as the moon experiences no force when attracting the earth, as the moon orbits the earth, where as the earth orbits the moon - as two distinct separate orbits.

Gravities graviton travels through the vacuum from earth to moon - where it interacts with any atomic particle of inertial mass - whereby that particle acquires acceleration in the direction to the source of the graviton!
Ojorf
3.3 / 5 (7) Aug 14, 2018
I can prove you wrong savvys84.
What do you think gravity is?

Chk my papers here https://www.scrib...savvys84
and prove me wrong


You didn't answer my question.

What do you think gravity is?
vlaaing peerd
5 / 5 (5) Aug 14, 2018
I can prove you wrong savvys84.
What do you think gravity is?

Chk my papers here https://www.scrib...savvys84
and prove me wrong


You are right. If you can disprove General Relativity by the means of a pendulum, I believe there will be no person or fact in the world that can prove you wrong.

Especially the part about waving the pendulum near an event horizon was convincing, truly solid science!
granville583762
3.3 / 5 (7) Aug 14, 2018
Gravities addition of gravitons
Where the sun attracts the earth by visible evidence of the tides, as the suns gravities graviton attracts the earth during a new moon where by the sun – moon – earth are in line, the graviton passes through inertial mass on it journey through the vacuum, the suns graviton attracts the moon and passes through the moon and attracts the earth, likewise the moons graviton attracts the earth.
The two gravitons combined increase the tidal ranges on earth, where the trillion upon trillion of gravitons passing through the vacuum from the sun and the moon attract the earth whereby they continue through the earth and continue through the trillions upon trillions of light years of the vacuum attracting any particles of inertial mass in the direction of the sun and moon at the point in the vacuum from the gravitons emission!
Because by this time the sun, moon and earth are no longer in the same coordinates.
Captain Skip
1 / 5 (6) Aug 14, 2018
OMG the comments are so funny Dark matter semetry and other hocus pokus
It can be shown that gravity is simply neutrino string inductive refraction.

the premise of dark matter violates the simple and basic Gaussian gravity rules that have been proven for centuries.. the gravitational effect of masses higher than you in a massive body cancel out and the effect is entirely based upon your distance from the center..

anybody who even accepts the premise of dark matter as the expansion of the universe is a fool and does not understand the basic inverse square law mathematics

Mass is not a property but an effect ... and inductive effect.

savvys84
1 / 5 (2) Aug 15, 2018
I can prove you wrong savvys84.
What do you think gravity is?

Chk my papers here https://www.scrib...savvys84
and prove me wrong


You are right. If you can disprove General Relativity by the means of a pendulum, I believe there will be no person or fact in the world that can prove you wrong.

Especially the part about waving the pendulum near an event horizon was convincing, truly solid science!

so how would the pendulum behave close to, or at, the event horizon?
Whart1984
Aug 15, 2018
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Whart1984
Aug 15, 2018
This comment has been removed by a moderator.
vlaaing peerd
5 / 5 (1) Aug 15, 2018

Chk my papers here https://www.scrib...savvys84
and prove me wrong


Especially the part about waving the pendulum near an event horizon was convincing, truly solid science!

so how would the pendulum behave close to, or at, the event horizon?


I assume close to EH the angle and frequency of the pendulum would increase with the increase of gravity. What happens on or beyond, I wouldn't know.
savvys84
1 / 5 (2) Aug 16, 2018

Chk my papers here https://www.scrib...savvys84
and prove me wrong


Especially the part about waving the pendulum near an event horizon was convincing, truly solid science!

so how would the pendulum behave close to, or at, the event horizon?


I assume close to EH the angle and frequency of the pendulum would increase with the increase of gravity. What happens on or beyond, I wouldn't know.

freq will be close to infinity as period becomes zero. thus time flow infinite. It is for this reason that the em wave cannot propagate at the EH and beyond
savvys84
1 / 5 (2) Aug 16, 2018
Kozyrev claimed, that processes which increase entropy, such as evaporation of acetone, always repelled the small mass, thus serving as a source of antigravity. In his terminology such processes "emit time," and create right handed torsion. No matter on which side of the arm the acetone was placed, it had the effect of pushing the small mass away. In some of his experiments a different type of torsion balance was used: a flat circle suspended in the center, instead of the long torsion arm. This is shown in the https://i.imgur.com/S8EwLiG.gif.

Kozyrev is onto something
howhot3
not rated yet Aug 17, 2018
The evaporation of acetone is a chemical effect but it's an interesting analogy to think about. If entropic gravity is real, it's a mind bender.
Whart1984
Aug 18, 2018
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Whart1984
Aug 18, 2018
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Hyperfuzzy
not rated yet Aug 29, 2018
The evaporation of acetone is a chemical effect but it's an interesting analogy to think about. If entropic gravity is real, it's a mind bender.

I question the logic. This is a derivation from non-causality, it does not have to be isomorphic; however your metamorphism is a probabilistic set of some of the most beautiful mathematics to explain nonsense; causal?

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