The End Of Gravity As a Fundamental Force

An anonymous reader writes "At a symposium at the Dutch Spinoza-instituut on 8 December, 2009, string theorist Erik Verlinde introduced a theory that derives Newton's classical mechanics. In his theory, gravity exists because of a difference in concentration of information in the empty space between two masses and its surroundings. He does not consider gravity as fundamental, but as an emergent phenomenon that arises from a deeper microscopic reality. A relativistic extension of his argument leads directly to Einstein's equations." Here are two blog entries discussing Verlinde's proposal in somewhat more accessible terms.
Update: 01/12 04:48 GMT by KD : Dr. Verlinde has put up a blog post explaining in simpler terms the logic of the gravity from entropy paper. He introduces it with: "Because the logic of the paper is being misrepresented in some reports, I add here some clarifications."

Comments

way cool

[drDugan]

FTA:"Starting from first principles, using only space independent concepts like
energy, entropy and temperature, it is shown that Newtons laws appear naturally and
practically unavoidably. Gravity is explained as an entropic force caused by a change
in the amount of information associated with the positions of bodies of matter. "

and "... the holographic hypothesis provides
a natural mechanism for gravity to emerge. It allows direct contact interactions
between degrees of freedom associated with one material body and another, since all
bodies inside a volume can be mapped on the same holographic screen."

If this is proven correct - that gravity and inertia are emergent from information entropy
and statistics, it would be very, very exciting if for no other reason than it would be yet
another support (probably the strongest yet) for the holographic universe description /
the 'reduced dimensionality' description. This could also resolve some of the impossibly
inconsistent problems in physics integrating gravity with microscopic forces and spooky
effects like action at a distance.

So far all we've had to support a holographic universe is black hole physics and string
theory conjectures.

It's mind warping to imagine that the whole of our existence necessarily depends
on encodings that are 2-dimensional in nature. If this is the case, what a world
it would be. Philosophers and religious folk will argue over what that might mean.

Re:way cool

[drDugan]

what does this potentially bring us

The paper posits that gravity is an entropic force, not a fundamental one. He does this by starting with the assumption of a reduced dimensionality universe with one emergent direction for space and shows that as a mass approaches the holographic boundary he can combine statistical mechanics equations and Einsteins equations for mass & energy (throw in a couple hand waves about average energy and degrees of freedom) and he derives Newton's laws and more.

This is fundamentally a different view of how gravity, inertia and space arise compared to the current "fundamental forces" understanding in physics. An accurate and testable understanding of gravity could potentially lead to areas impossible to predict: anti-gravity, energy production, warping and changing space, usable action at a distance for communication or transportation.

This is analogous to the shift in understanding when humans understood and then used the electrical force. Who could have dreamed before electric power of mobile phones, global Internet connectivity, HDTV, Twitter, Superbowl broadcasts, images from Mars, superconducting MRI coils, particle accelerators, etc. etc. A functional understanding of gravity could be even more revolutionary than the change in the human condition from understanding electricity.

Re:Just because the math works doesn't mean it's t

[Anonymous Coward]

Well, it does make a jump from a fundamental force we can't seem to detect into a latent, emergent phenomenon which we, er, also can't detect the source of.

So it transfers one critical unknown into a less important, impossible to verify unknown. Then it links up with Relativity somehow. Not exactly a "theory of everything".

Re:Just because the math works doesn't mean it's t

[Zarf]

I do like the idea of not needing an explanatory tool like "Dark Energy" ... that has always bothered me. Far more than "Dark Matter".

Re:Just because the math works doesn't mean it's t

[node 3]

That's one funny thing about math, "close doesn't count", until you get to a certain advanced point.

I didn't realize irrational numbers, a huge portion of the rational numbers, and trigonometry, were considered advanced.

But this really isn't about the *math* being close, but not exact, it's about the math being close to *reality*, but not exact. Again, however, this is not advanced. Even grade school science is close but not exact. What's the temperature outside? How many inches of water did it rain last night? What's the circumference of the Earth? And Newtonian physics (which is also not advanced) is close, but not exact. Even at the slow speeds and low gravities of our mundane lives. Special and General Relativity have the honor *not* of being exact, but merely of being closer to exact than anything else so far.

The only common types of math where "close doesn't count" are basic arithmetic (excepting fractions) and pure algebraic manipulation.

In your high school physics class, do you *really* think you were exact when you used 186,000 mi/s or 300,000 km/s for the speed of light? Or in grade school, that the Earth rotates in exactly 24 hours (as measured from solar zenith to solar zenith)?

Or even before that, when you bought one candy bar at 3 for a dollar, and you got 66 cents in change?

Precision and accuracy are two terms you should have been made aware of by high school science, and rounding errors by middle school math.

Re:What is "information"? (In that context.)

[FooAtWFU]

Dude! Information is a perfectly useful theoretical property in theoretical physics, directly related to entropy. Observe, for instance, all the cool stuff Stephen Hawking has done is related to black hole entropy in some manner or another. (Black holes have to have entropy, otherwise you could violate the second law of thermodynamics by tossing stuff into them.... but if they have entropy, they should emit radiation.... hey, guys, look, a way for black holes to emit radiation and evaporate!!)

As Jacob Bekenstein put it, the trend in physics is to "regard the physical world as made of information, with energy and matter as incidentals." (Bekenstein came up with the Bekenstein bound, a fundamental limit on the amount of information/entropy which can be contained within a space. If you could come up with a system with more entropy in a given space, then you might be able to violate the Second Law of Thermodynamics by tossing it into a black hole.)

In his theory, gravity exists because of a difference in concentration of information in the empty space between two masses and its surroundings.
In his theory, gravity exists because of a difference in concentration of entropy in the empty space between two masses and its surroundings.
Same darned thing.

Re:Stop posting articles from arXiv!

[MadMagician]

If you've spent any time in academia, you'd know that peer review is a cruel joke.

It's more politics than science.

Somebody didn't get tenure.

I didn't get tenure either, and there were serious political issues, the first time. But that's not a problem with peer review (which I still am asked to do, occasionally). Most PhD's never get tenure, at least not in a research university. Academia is one bitch of a career path.

I still publish papers, in less-prestigious journals and conferences, mostly peer-reviewed. Some papers are turned down. So it goes...

Re:Just because the math works doesn't mean it's t

[statusbar]

While I agree with your basic premise, let's examine your statement with regards to the number PI.

We have a whole bunch of different equations that calculate what PI is to billions of digits of accuracy.

Is our model of PI more accurate than our measurement of a circle in reality?

Does this mean our model of PI can not be more accurate than our measurements?

Or is there some other way to 'prove' that our model of PI is exact regardless of what our universe measures it as?

--jeffk++