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posted by martyb on Thursday November 10 2016, @12:31AM   Printer-friendly
from the it's-all-an-illusion dept.

Theoretical physicist Eric Verlinde has finally published his much anticipated article on the nature of gravity. In a 2010 New York Times article Verlinde already stated: gravity is an illusion. His theory goes beyond the concept of gravity as envisioned by both Isaac Newton and Albert Einstein. It will be very interesting to see other scientists sink their teeth into this.

Abstract of his article:

Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional 'dark' gravitational force describing the 'elastic' response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton's constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional 'dark gravity force' explains the observed phenomena in galaxies and clusters currently attributed to dark matter.

Heck, I'm not even going to pretend I grok any of this: I shine shoes for a living and just hope that my understanding of gravity-as-we-know-it is sufficient to catch the coins customers drop into my weary hand.


Original Submission

 
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  • (Score: 2) by frojack on Thursday November 10 2016, @01:01AM

    by frojack (1554) on Thursday November 10 2016, @01:01AM (#424946) Journal

    Yeah, I don't understand it either but I just read about it yesterday.

    Illusion is probably not the right word. But the other words don't help much either: [dailymail.co.uk]

    His controversial suggestion says gravity is not a fundamental force of nature at all, but rather an 'emergent phenomenon'.

    This can be thought of as the same way temperature is an emergent phenomenon, arising from the movement of microscopic particles.

    The new theory, called 'emergent gravity', suggests gravity comes as a side-effect of the entropy of the universe.

    Professor Verlinde's took the entropy of the universe and used it to adapt a theory called the holographic principle.

    He says gravity emerges from the changes of fundamental bits of information, stored in the structure of spacetime.

    Now isn't that a lot clearer? I thought so.

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  • (Score: 3, Interesting) by Thexalon on Thursday November 10 2016, @01:47AM

    by Thexalon (636) on Thursday November 10 2016, @01:47AM (#424949)

    Well, if the math works, and it holds up under tests, that sure sounds like the beginnings of a Grand Unified Theory (uniting the physics of very small things, i.e. quantum mechanics, and the physics of very large things, i.e .relativity) that stumped Einstein, Bohr, and a lot of other very smart physicists. I can understand Verlinde wanting to explore along those lines.

    On the other hand, a bit early to go to the press with it when you're still in the hypothesis stage, eh? It sure seems like you're fishing for a Nobel there.

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    • (Score: 2) by frojack on Thursday November 10 2016, @01:53AM

      by frojack (1554) on Thursday November 10 2016, @01:53AM (#424954) Journal

      But the dark matter math works out too, no?

      (Other than all that missing dark matter, mumble mumble).

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      • (Score: 3, Interesting) by lgw on Thursday November 10 2016, @04:07PM

        by lgw (2836) on Thursday November 10 2016, @04:07PM (#425164)

        I'm quite skeptical of this because is claims to explain one part of what dark matter explains without explaining the rest. Immediately my crackpot alarms sound.

        Dark matter explains: galaxy/cluster rotation rates and the distribution of matter in the early universe and gravitational lensing where there's no visible matter. Cranks focus on the first, and ignore the other two.

    • (Score: 1) by khallow on Thursday November 10 2016, @03:36PM

      by khallow (3766) Subscriber Badge on Thursday November 10 2016, @03:36PM (#425155) Journal

      On the other hand, a bit early to go to the press with it when you're still in the hypothesis stage, eh?

      Do you think Mr. Verlinde has the experimental apparatus to verify his theory? Going to the press is the next step.

  • (Score: 3, Interesting) by Gaaark on Thursday November 10 2016, @02:16AM

    by Gaaark (41) on Thursday November 10 2016, @02:16AM (#424960) Journal

    "emergent phenomenon, arising from the movement of microscopic particles."

    This reminds me of Julian Barbour's theory that time and space are separate and that time only exists due to the movement of things in space: time is emergent from movement in space.

    Maybe gravity and time only exist because particles move in space: no movement, no gravity, no time.

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    • (Score: 2, Insightful) by tftp on Thursday November 10 2016, @04:41AM

      by tftp (806) on Thursday November 10 2016, @04:41AM (#425000) Homepage

      Maybe gravity and time only exist because particles move in space: no movement, no gravity, no time.

      How would you detect the movement without having time to measure its speed?

      • (Score: 0) by Anonymous Coward on Thursday November 10 2016, @09:48AM

        by Anonymous Coward on Thursday November 10 2016, @09:48AM (#425065)

        But how would you define and measure time without processes which involve moving?

        Time and movement are just two views of the same thing. By default we used to chose the time as primary view, but relativity suggests we should pick the movement for better understanding of the world.

        • (Score: 0) by Anonymous Coward on Thursday November 10 2016, @02:53PM

          by Anonymous Coward on Thursday November 10 2016, @02:53PM (#425135)

          But how would you define and measure time without processes which involve moving?

          Using processes that change some properties of something while staying in place?

  • (Score: 2) by Nerdfest on Thursday November 10 2016, @02:47AM

    by Nerdfest (80) on Thursday November 10 2016, @02:47AM (#424970)

    Isn't gravity generaly thought of as an emergent property of mass these days anyway? Emergent from entropy is a very different take on it though.

    • (Score: 2, Informative) by Anonymous Coward on Thursday November 10 2016, @08:52AM

      by Anonymous Coward on Thursday November 10 2016, @08:52AM (#425041)

      No. Emergent is something different than "caused by" or "coupled to". As an example, the American two-party system is an emergent phenomenon of the US election system: Nowhere in the constitution or elsewhere it is prescribed that there shall be only two big parties. But the way the system works, most of the time only two big parties will emerge.

      Neither Newtonian nor Einsteinian gravitation is of that type; in both theories gravitation there is an explicit gravitational field (resp. spacetime curvature) the mass (resp. energy and momentum) couples to. Also in quantum gravitation theories, gravitation usually is explicitly included either as field (mediated by the graviton), or in the form of a quantized curved spacetime (as in loop quantum gravitation).