
Emergent Gravity and the Dark Universe - mrreelmo
https://arxiv.org/abs/1611.02269
======
supermatou
Also, a simple explanation for the layman:
[http://www.alphagalileo.org/ViewItem.aspx?ItemId=169788&Cult...](http://www.alphagalileo.org/ViewItem.aspx?ItemId=169788&CultureCode=en)

~~~
pmontra
Thanks for the link (+1) but it's very far from being an explanation for the
layman.

> In the same way that temperature arises from the movement of microscopic
> particles, gravity emerges from the changes of fundamental bits of
> information, stored in the very structure of spacetime.

It doesn't explain how gravity emerges from bits of information. I'd love to
understand how those bits make apples move from trees to the ground, the
equivalence between gravity and acceleration and the weightless free fall
experience. That should be one paragraph for the general principle and one for
each example. Then it's for the layman, and me too :-)

~~~
ajcarpy2005
It's funny how scientists always reference time in relation to gravity and yet
separate out gravity from other forces of motion when the implicate order
would be to have gravity always playing a role in motion whatever the axis or
motion of travel.

The other thing to know is that for a wave, there are more motions of travel
than upon a triune 3-dimensional axis. The common thought process of a
pondering individual is to simply add singular 3-dimensional particles to a 4,
5 or more dimensional time-space environment and try to peer into the
behaviors of a hyperspatial-capable environment.

This is ridiculous because in a hyperspatial environment, so-called objects
have a tendency to be in more of a wave-like state and even more-so than the
waves of an ocean. These waves would be more like a fine-cotton tuft which is
being pulled by electrostatic strands in multiple directions at once and
wherein the "identities" of each may out of behavior dynamics be considered as
singular with multiple locations because of a tendency to collapse at the same
time or leave one the strongest through a matrix interconnections consisting
of concepts of "Tensegrity." <wiki it.

Then you have photons which are thought to be low-mass or perhaps even zero or
negative in mass. This seems to correlate nicely with their high-speed
velocities.

In a Universe which has hyper-spatial dimensions not only overlaying reality
but also underpinning it via multiple directions (like the gravity of multiple
stars, planets, and moons affecting each planetary body), the hyper-spatial
arenas would seem to be more elastic and able to slip and slide over and
around the greater reality. Mystics and even scientists talk about these other
dimensions as a deeper reality but it might be fair to take it with a grain of
salt and see our current average reality as the "deeper reality."

So gravity is the "sums" of multiple affecting bodies. The datastreams coming
in from the Sun, Moon, and other planets all affect life on Earth. The Moon
mostly contributes to water while other elements likely have greater response
to other planetary bodies, depending on their molecular and nuclear
composition. (although this has not been published in the traditional
manuscripts of current science)

Anyway, to answer the question in the way I think of it, gravity is related
more closely to time than the way in which science usually connects time to
gravity. Scientists usually act like a photon travels at the 299 792 458 m / s
rate.

It would seem that whatever forces of information flow (entropy...and some
would say proto-consciousness) are behind gravity - are also interrelated with
time itself.

Here's the kicker. People assume everything falls to Earth. Why? Because most
things do? What about balloons filled with Helium? What about light which
reflects to the astronauts in space? What about the electrical currents
flowing to the Sun and back in the chains of ions? How much mass is held in
those ions?

And that's just talking "vertically" without reference towards the hyper-
spatial dimensions which the common man has even less experience with - even
though we are experiencing the interactions with these dimensions all the
time.

Let me make an important note before I forget: Electromagnetic forces may very
well be different enough from "gravity forces" to be differentiated but there
may also certainly be some overlap at various scales or in high-voltage or
highly-sophisticated quantum situations.

Whichever ways in which time is generated/observed/transmitted, both gravity
and electromagnetic forces are bound to be related with the flow & effects.
____If information is practically as important as energy and gravity, how much
information leaves Earth through light or ionic currents which flow to the Sun
(or other stars?) __ __

Also, to the person who also answered here and said electromagnetism can never
be related with gravity, how do they imagine ions are moving through a wire or
exchanged in an electrolyte solution of a battery or a hydrogen-production
system? Again, to change the angle to "vertical" rather than horizontal is a
weird way to classify an entirely different force.

Oh...as I was saying, :) it's all about the timing. In a coherent stream of
information like a flow of photonic light or the flow of electrons in an
electromagnetic current, the forces of motion are resistant to changes in the
flow of time within their area of influence. Next move your attention to the
heat we can "see" radiating from the smokestack of a semi tractor. This
thermal emission is a form of energy which is slightly more disordered and
"dispersed" than the kinds of "motion" we "see" elsewhere.

One would possible assume that if we get so close to Earth where we are
essentially at "ground-level" and we allow the gravity well to exert its
influence on an object, that the strong effect we see is because there is a
very "unified" pull of forces. But this is just as false as if we get closer
to a cable being weaved from dozens of smaller diameter threads. We begin
'seeing' the smaller threads are spread further apart as we change our
perspective to a smaller and closer entity.

Why do we see water swirling different rotations into a drain on different
places upon Earth? All to due with the nature of time, gravity, and space
itself being shaped and molded by a force which is positional and situational
and thus inherently "proto-conscious."

Link: Implicate Order:
[http://www.bizint.com/stoa_del_sol/plenum/plenum_3.html](http://www.bizint.com/stoa_del_sol/plenum/plenum_3.html)

~~~
andrepd
I don't have time to go over all your post, but you seem to be very very
confused about several things. I suggest you try to read a science
communication book, like Carl Sagan or the sort.

------
mrreelmo
An explanation by the author:
[https://www.youtube.com/watch?v=ynRVnIh6wq4](https://www.youtube.com/watch?v=ynRVnIh6wq4)

------
autocorr
There is a great deal of observational evidence favoring Lambda-Cold-Dark-
Matter, ie the status quo of cosmology with dark matter. The bullet cluster
[1] is evidence for two colliding galaxy clusters where the luminous matter
ran into itself but the dark matter kept going. The total mass (luminous plus
dark) can be mapped out with the gravitational lensing of background galaxies
and can be done very accurately. This was essentially the nail in the coffin
for the leading alternative theory modified newtonian dynamics (MOND).

Dark matter is so deeply embedded into cosmology and modern astrophysics, you
would have to explain a host of solidly observed phenomena to be a compelling
alternative (baryon acoustic oscillations, the cosmic microwave background,
primordial abundances, the evolution of structure or the "cosmic web").
Comparing to those things would probably take man-decades of work and also
require computationally expensive cosmological simulations on super computers,
so I'm skeptical we will see the kind of theoretical/observational comparison
that would make you sit up and take notice.

[1]
[https://en.wikipedia.org/wiki/Bullet_Cluster](https://en.wikipedia.org/wiki/Bullet_Cluster)

------
eloff
I love this, it feels cleaner and more elegant a solution than dark matter
particles. However, nature doesn't care what we like, so that doesn't make it
more likely to be true.

~~~
eli_gottlieb
I agree that it sounds elegant, especially since it puts entropy/information
into the core ontology so as to explain the arrow of time and thermodynamic
behavior _as part of_ the same theory that can account for Einsteinian space-
time.

I just wish I understood enough physics to tell this paper from elegant-
sounding word salad!

------
taliesinb
If you're wondering how this isn't some weird form of MOND, which is basically
dead as an explanation, here's an important paragraph from the paper:

> We like to emphasize that we have not derived the theory of modified
> Newtonian dynamics as proposed by Milgrom. In our description there is no
> modification of the law of inertia, nor is our result (7.43) to be
> interpreted as a modified gravitational field equation. It is derived from
> an estimate of an effect induced by the displacement of the free energy of
> the underlying microscopic state of de Sitter space due to matter. This
> elastic response is then reformulated as an estimate of the gravitational
> self-energy due to the apparent dark matter in the form of the integral
> relation (7.40). Hence, although we derived the same relation as modified
> Newtonian dynamics, the physics is very different. For this reason we
> referred to the relation (7.43) as a fitting formula, since it is important
> to make a clear separation between an empirical relation and a proposed law
> of nature. There is little dispute about the observed scaling relation
> (7.43), but the disagreement in the scientific community has mainly been
> about whether it represents a new law of physics. In our description it does
> not.

------
slicktux
[https://news.ycombinator.com/item?id=12526559](https://news.ycombinator.com/item?id=12526559)

------
MrQuincle
There seems to be considerable disagreement in the field. Why is it news (I
really would like to know!)?

\+ Kobakhidze explaining neutron experiments:
[https://arxiv.org/abs/1108.4161](https://arxiv.org/abs/1108.4161)

\+ [http://physics.stackexchange.com/questions/4289/is-
gravity-a...](http://physics.stackexchange.com/questions/4289/is-gravity-an-
entropic-force-after-all)

\+ Lubos Motl: [http://motls.blogspot.nl/2010/01/erik-verlinde-why-
gravity-c...](http://motls.blogspot.nl/2010/01/erik-verlinde-why-gravity-cant-
be.html) and [http://motls.blogspot.nl/2010/01/erik-verlinde-comments-
abou...](http://motls.blogspot.nl/2010/01/erik-verlinde-comments-about-
entropic.html)

It's nice to see that also experts in these highly specified fields quarrel
about what it means to be "entropic" and "irreversible", etc.

------
323454
> The central idea of this paper is that the volume law contribution to the
> entanglement entropy, associated with the positive dark energy, turns the
> otherwise “stiff” geometry of spacetime into an elastic medium. We find that
> the elastic response of this ‘dark energy’ medium takes the form of an extra
> ‘dark’ gravitational force that appears to be due to ‘dark matter’.

------
plank
Discussion in Dutch: [http://www.volkskrant.nl/wetenschap/ineens-klopt-het-
univers...](http://www.volkskrant.nl/wetenschap/ineens-klopt-het-universum-
zwaartekrachttheorie-erik-verlinde-in-zes-lekenvragen~a4411221/)

------
zer0gravity
I think it helps a lot to try to understand the universe from an engineering
perspective, thus by posing the question "How would I build a universe?" The
apparent obvious answer is : as an N dimensional matrix where each cell
executes some code.

With such a setup, effects like gravity, are more probable to be emergent
effects.

Another consideration is that in such a setup the only thing that matters is
the state of the matrix, in other words there is no time, just iterations.

So my 2 cents are: gravity should be explained as an emergent phenomenon, and
time should be removed from all equations that try to explain the underlying
fabric of reality.

------
mcbits
> According to the holographic principle, all the information in the entire
> universe can be described on a giant imaginary sphere around it. Verlinde
> now shows that this idea is not quite correct: part of the information in
> our universe is contained in space itself.

I thought the holographic principle just said the _amount_ of information in
any physical structure (up to the whole universe) was such that it _could_ fit
on a 2D surface the size of the event horizon of the structure, not that it
actually is contained on the surface. Does this theory change that?

------
hammock
Gravitons always struck me as a goofy half-baked concoction (even though we've
supposedly observed them now), and so did dark matter. Emergent gravity
theories are very interesting.

~~~
wanda
> even though we've supposedly observed [gravitons] now

Source? Or are you saying that the existence of gravitational waves constitute
a proof of the existence of gravitons, due to wave/particle duality?

I'm not a physicist, but all I thought we had detected were gravitational
waves.

~~~
TeMPOraL
> _the existence of gravitational waves constitute a proof of the existence of
> gravitons, due to wave /particle duality_

I always thought this is the case. But IANAP either. Could anyone with actual
knowledge chime in?

~~~
ars
No, a gravitational wave has mass (carries mass is more accurate), but a
graviton does not. They are not two aspects of the same thing.

~~~
empath75
In a quantum field theory, a wave implies a force carrying particle, does it
not?

~~~
codethief
To be precise, particles (with precise momentum) are certain modes or
excitations of a quantum field which is often governed by something like a
wave equation. However, not all quantum fields (and their associated
particles) are force carriers. These are usually just the gauge bosons.

In any case, though, noone has managed to quantize gravity yet (i.e. describe
gravity as a quantum field theory with gravitons as force carriers), so we've
detected just gravitational waves but no gravitons.

~~~
raattgift
Well, we've quantized gravitation extremely well - it's just perturbative
quantum gravity, of which there are a couple flavours. In weak gravity it
makes predictions identical to General Relativity, but is taken to be an
effective field theory (in the Charles Wilson sense of "effective) in that we
do not know how to deal with Feynman diagrams with more than a loop or two of
gravitons, which only happens in strong gravity.

In these theories, gravitons are quantizations of the weak-field
perturbations.

The non-renormalizability by power-set counting of gravity because it is a
long-range force is a good result of perturbatively quantized gravity. Who
knows if there is a workable way of renormalization by other methods? Not me.

Since we don't get strong gravity except close to a black hole singularity or
in the extremely early universe, it's unfair and premature to say that the EFT
approach has been unsuccessful.

------
cshreve
So I too love the idea that we don't need dark matter to explain all the
gravitational effects we observe in the universe. However, is it just me or
does the falsification of this seem a bit sketchy: if we find a dark matter
particle...then my theory is false. That's a bit like saying...oh yeah if we
find a different way to unify general relativity and quantum mechanics...then
String Theory is false. It seems like there should be a 'smaller' way to
falsify it.

~~~
jcoffland
I think you will find all the models are false to a degree. A model is only an
approximation of the real thing. Quantum mechanics and General relatively
cannot both be right. The obvious answer is that they are both wrong.

~~~
zamalek
A thought experiment of mine.

Assume that all possible hypothesis or theories (explanations in general) form
part of an "explanation space." Some explanations are good (theories), some
have no evidence (hypothesis) and some are false (we are riding a giant
turtle). Given the number of false explanations, the overall space is
infinite. Hypothesis spaces would be islands within the false explanation
space, theories islands within hypothesis and the truth as a single point
within one of those theory spaces.

The question is, does that mean that the theory space is infinite? _If_ so,
that would mean that it would be impossible to know that we've found the truth
(as a single point within this infinite space) - we'd only ever be able to
conclude that we've found a closer approximation. Scientists may never run out
of work.

~~~
eli_gottlieb
>The question is, does that mean that the theory space is infinite? If so,
that would mean that it would be impossible to know that we've found the truth
(as a single point within this infinite space) - we'd only ever be able to
conclude that we've found a closer approximation. Scientists may never run out
of work.

The theory space is _definitely_ infinite, in either the interesting sense of
something like "the space of all possible programs, treated as causal or
directed-generative models" or in the trivial sense that you can take any
simple, well-supported theory and come up with mathematical elaborations that
don't change any of the pre-existing empirical predictions.

In a certain sense, "the truth" may constitute an infinitely small point in a
space that's more continuous than discrete.

------
slowmovintarget
In the summary, it says that these theories are "best understood in Anti de
Sitter space...". I thought current observations ran against a spacetime that
had a negative curvature. Are they just saying the math is easier in that
geometry, but that it still applies to flat (or ever-so-slightly-positively
curved) spacetime? Or are they arguing in favor of a "saddle-shaped" universe?

~~~
maverick_iceman
Spacetime has a positive cosmological constant, so it's closer to de-Sitter
than Anti de-Sitter. It doesn't really have to do with curvature exactly,
which is given by the Riemann tensor (so it doesn't make sense to say it's
positive/negative).

~~~
codethief
But you certainly can talk about curvature scalars being positive/negative
which are derived from the Riemann tensor.

------
spynxic
Imagining gravitational waves inevitably leads me to believe that gravity is a
force that varies (in a cycle) over spacetime. But.. what exactly does it mean
to propagate over a cycle in spacetime? (particularly the time aspect confuses
me since something propagating in space remains constant in time (either
accelerating or decelerating)

------
novalis78
Does this in any way match with Lipinski's gravity discussion
([http://adsabs.harvard.edu/abs/2008AcPPB..39.2823L](http://adsabs.harvard.edu/abs/2008AcPPB..39.2823L))
that was mentioned here just recently (unifiedgravity.com)?

------
benibela
I do not understand this stuff, but the connection between gravity and
horizont sounds like this [quantized acceleration
theory]([http://physicsfromtheedge.blogspot.de/](http://physicsfromtheedge.blogspot.de/))

------
jpm_sd
I'm currently reading The Confusion [0] and just got through Leibniz's
explanation of monadology [1][2]. Summarized very very briefly, the idea is
that every particle in the universe is a sort of computational device, and
their actions/reactions are determined by their "perception" of all the other
particles in the universe.

Does this research suggest that he may have been semi-correct??

[0]
[https://en.wikipedia.org/wiki/The_Confusion](https://en.wikipedia.org/wiki/The_Confusion)
[1]
[https://en.wikipedia.org/wiki/Monadology](https://en.wikipedia.org/wiki/Monadology)
[2] [https://quantummoxie.wordpress.com/2014/09/09/neal-
stephenso...](https://quantummoxie.wordpress.com/2014/09/09/neal-stephenson-
on-leibniz-monads-and-more/)

~~~
tpeo
Frankly, I'd be surprised if anything ever suggested that Leibniz's colorful
metaphysics was correct, even or incorrect.

Leibnizian monads are unextended and unable to act on one another (from §1 and
§7 of the Monadology), which is to say that they're non-physical. On the other
hand, as they're somehow supposed each to have a complete picture to the world
(§56), they imply some form of non-locality. Which is to say that they're some
very _spooky_ things.

The thing that comes closest to Leibniz's monadology is the idea that the
world is a simulation running inside a computer. But Leibniz's idea was more
like that there is an arbitrarily large number of computers running the same
simulation, while some of them also run artificial intelligences which just
watch the simulation unfold.

Which is an idea I think can be fairly described as "completely nuts".

~~~
wcoenen
> But Leibniz's idea was more like that there is an arbitrarily large number
> of computers running the same simulation, while some of them also run
> artificial intelligences which just watch the simulation unfold.

I think this was just Leibniz awkward attempt at explaining modal realism. The
idea of many possible worlds is much more mainstream now in physics, so I
wouldn't call it "completely nuts".

~~~
tpeo
I wasn't previously acquainted with the term "modal realism" (been avoiding
contemporary philosophy for a while now), but there doesn't seem to be an
immediate connection in this case. There aren't actually many worlds being
simulated here, as each computer simulates the same world and they all get the
same results. Leibniz does introduce the idea of many possible worlds (§53),
but as a set of designs for this whole thing (computers plus the stuff running
inside them) from which God draws one particular design to be the actual
world.

He might be closer to modal realists in other regards, though. I don't know.

------
zmanian
Does entropic gravity explain the lensing phenomenon attributed to dark
matter?

------
rudolf0
To what degree does this contradict Einstein's theory of gravity?

~~~
teilo
It does not contradict Einstein's theory of gravity, just as Einstein did not
contradict Newton. All three are different models explaining progressively
more thorough levels of observation.

Don't think of a theory so much as "what is true" but rather as a set of
propositions and equations which are designed to model the way physical
processes are observed to occur.

Theories exist within their own provenance of observation. Both Einstein and
Newton's theories reflect reality within certain limits, but outside those
limits they do not. To allow Einstein's theory to apply at larger scales, we
proposed dark matter because Einstein could not account for the behavior of
galaxies unless there was some hidden element involved. Thus we proposed dark
matter. It is a reasonable accommodation, but one that has defied
confirmation.

The emergent theory embraces both Newton and Einstein, eliminates any need for
dark matter, and attempts to explain all current observations within a single
framework.

Einstein's theory made testable predictions which were later proven to be
true. The emergent theory lacks such confirmation, and so time will tell
whether it reflects reality.

~~~
eli_gottlieb
>Einstein's theory made testable predictions which were later proven to be
true. The emergent theory lacks such confirmation, and so time will tell
whether it reflects reality.

The author claims to be making a few novel predictions which, he claims,
astronomers can go check. He also retrodicts several things we observe, though
I'm not enough of a physicist to say if he's using a simple enough model for
that to be interesting.

------
nedsma
How does the theory explain unaccountable 96% of the universe which we cannot
observe/detect? Is there a thing such as antibaryonic matter?

------
mrfusion
Like others have mentioned I'm not sure what happens now to the gravity waves
we've detected.

~~~
ars
I'm not convinced we have in fact detected gravity waves. From our point of
view merging black holes would not move due to time dilation, but the waves
detected are modeled after black holes without time dilation.

Although it's possible we detected a wave from a different source, not a black
hole.

~~~
empath75
While we can never see them merging completely, we can see them asymptotically
approach a merger, which does in fact take about 1/5th of a second to get most
of the way there.

------
ilostmykeys
How about Dark Meat? I like Dark Meat.

