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I get the premise (gravity becomes linear at large distance), but I don't understand any of the terms used in the article, and their respective pages didn't do

I get the premise (gravity becomes linear at large distance), but I don't understand any of the terms used in the article, and their respective pages didn't do anything to help. Could someone give an ELI5 of entropic forces, anti de-Sitter space, and the rest of the opening paragraph?

sklivvz1971 7y ago
Basically, from the "derivation" in the page: 1) Two point-masses at a distance subtend a sphere with the radius equal to the distance 2) That sphere has a radius and a maximum capacity for holding information (in bits) depending on the area and the Planck constant 3) If we treat the bits as particles in a gas, we can derive the temperature of that gas based on the mass of one of the two point-masses and Einstein's equivalence 4) Assuming that the temperature is due to Unruh effect, we can calculate the acceleration that would cause it 5) Lo and behold, this is the same acceleration due to Newton's law of gravitation
cryptonector 7y ago
Without endorsing it, and presenting it here without comment, http://physicsfromtheedge.blogspot.com/ http://physicsfromtheedge.blogspot.com/ has explanations of the theory preferred there (which I think can be labeled an entropic theory of inertia, or perhaps an information-theory-based theory of inertia) that might be an ELI5. The following is my attempt at casting McColloch's idea as an ELI5. McColloch's idea is that inertia is a result of asymmetric Unruh radiation pressure resulting from acceleration causing the Hubble horizion sphere around the accelerated body to not be symmetrically spherical. The idea is that when you accelerate, then the Hubble horizon "behind" you gets much closer to you, which then disallows some Unruh radiation behind you, thus causing there to be more Unruh radiation pressure in front of you. A more fundamental idea underlying this is that Unruh radiation emanating from the Hubble (and, indeed, any) horizon has every possible discrete wavelength that would fit between the horizon and the particle surrounded by that horizon, so as the distance to the horizon changes, so does the longest wavelength that could be visible -that could exist-. Now, as accelerations tend to zero, the idea is that the number of Unruh waves that are disallowed by the horizon behind is much smaller than at higher accelerations, and therefore inertia drops at lower accelerations, leading to gravity feeling stronger. I believe all entropic gravity/inertia theories are at least as controversial as dark matter theories or more so. McColloch's has the benefit of having a physical explanation that can be explained, if not to a 5-year old, then to a 10-year old. However, keep in mind that it could be a simple explanation that is just wrong.

sklivvz1971 7y ago

Basically, from the "derivation" in the page: 1) Two point-masses at a distance subtend a sphere with the radius equal to the distance 2) That sphere has a radius and a maximum capacity for holding information (in bits) depending on the area and the Planck constant 3) If we treat the bits as particles in a gas, we can derive the temperature of that gas based on the mass of one of the two point-masses and Einstein's equivalence 4) Assuming that the temperature is due to Unruh effect, we can calculate the acceleration that would cause it 5) Lo and behold, this is the same acceleration due to Newton's law of gravitation

cryptonector 7y ago

Without endorsing it, and presenting it here without comment, http://physicsfromtheedge.blogspot.com/ http://physicsfromtheedge.blogspot.com/ has explanations of the theory preferred there (which I think can be labeled an entropic theory of inertia, or perhaps an information-theory-based theory of inertia) that might be an ELI5. The following is my attempt at casting McColloch's idea as an ELI5. McColloch's idea is that inertia is a result of asymmetric Unruh radiation pressure resulting from acceleration causing the Hubble horizion sphere around the accelerated body to not be symmetrically spherical. The idea is that when you accelerate, then the Hubble horizon "behind" you gets much closer to you, which then disallows some Unruh radiation behind you, thus causing there to be more Unruh radiation pressure in front of you. A more fundamental idea underlying this is that Unruh radiation emanating from the Hubble (and, indeed, any) horizon has every possible discrete wavelength that would fit between the horizon and the particle surrounded by that horizon, so as the distance to the horizon changes, so does the longest wavelength that could be visible -that could exist-. Now, as accelerations tend to zero, the idea is that the number of Unruh waves that are disallowed by the horizon behind is much smaller than at higher accelerations, and therefore inertia drops at lower accelerations, leading to gravity feeling stronger. I believe all entropic gravity/inertia theories are at least as controversial as dark matter theories or more so. McColloch's has the benefit of having a physical explanation that can be explained, if not to a 5-year old, then to a 10-year old. However, keep in mind that it could be a simple explanation that is just wrong.