Just reading about entropic gravity.

How come no-one here ever talks about this stuff?

The Rev Dodgson said:

Just reading about entropic gravity.

How come no-one here ever talks about this stuff?

because it is usually called emergent gravity. verlinde. sounds quite good, and it is backed to some extent by observation.

ChrispenEvan said:

The Rev Dodgson said:

Just reading about entropic gravity.

How come no-one here ever talks about this stuff?

because it is usually called emergent gravity. verlinde. sounds quite good, and it is backed to some extent by observation.

OK, I don’t recall seeing anything about emergent gravity here either.

Sarahs mum’s little grandson was teaching his dog about entropy recently.

Don’t think he’d post here, we’re too lowbrow.

The Rev Dodgson said:

Just reading about entropic gravity.

How come no-one here ever talks about this stuff?

I don’t know enough about it to be able to contribute.

Never heard of it before. Interesting, thanks.

https://en.wikipedia.org/wiki/Entropic_gravity

reckon i’ve come near it many times, when referring to gravity as a transducer, and that gravity communicates information about mass

The Rev Dodgson said:

ChrispenEvan said:

The Rev Dodgson said:

Just reading about entropic gravity.

How come no-one here ever talks about this stuff?

because it is usually called emergent gravity. verlinde. sounds quite good, and it is backed to some extent by observation.

OK, I don’t recall seeing anything about emergent gravity here either.

> Entropic gravity provides the underlying framework to explain Modified Newtonian Dynamics, or MOND

That’s where I’ve heard of it before. And why it isn’t worth believing.

The general relativistic form of MOND is now called f ( r ) gravity, where the strength of gravity is chosen in an arbitrary and unscientific way. Plkanck searched for f ( r ) gravity and didn’t find it.

mollwollfumble said:

The Rev Dodgson said:

ChrispenEvan said:

because it is usually called emergent gravity. verlinde. sounds quite good, and it is backed to some extent by observation.

OK, I don’t recall seeing anything about emergent gravity here either.

> Entropic gravity provides the underlying framework to explain Modified Newtonian Dynamics, or MOND

That’s where I’ve heard of it before. And why it isn’t worth believing.

The general relativistic form of MOND is now called f ( r ) gravity, where the strength of gravity is chosen in an arbitrary and unscientific way. Plkanck searched for f ( r ) gravity and didn’t find it.

> From algebraic substitution of these into the above relations, one derives Newton’s law of universal gravitation:

But this is interesting, somewhat.

For starters, the first equation has a free constant (not shown). So in a sense we’re back-deriving this from Newton’s law of gravitation.

The insistence on assigning bits of information to Planck volumes first of all means that we have to get down to inaccessible lengths to see any deviation from Newton’s law of gravity. Do you see a problem with that?

Unruh radiation is iffy. It’s not particularly reliable.

Now, I can see how large hidden dimensions could lead to an increase in length scale making deviations from Newton’s law of acceleration accessible. But large hidden dimensions were searched for by the LHC and not found.

Although a replacement of Planck volumes by some other TOE such as loop quantum, superstrings or causal dynamical triangulation could lead to an emergent gravity, but only an emergent gravity that deviates from Newtonian gravity on scales too small to detect using current equipment.

mollwollfumble said:

The Rev Dodgson said:

ChrispenEvan said:

because it is usually called emergent gravity. verlinde. sounds quite good, and it is backed to some extent by observation.

OK, I don’t recall seeing anything about emergent gravity here either.

> Entropic gravity provides the underlying framework to explain Modified Newtonian Dynamics, or MOND

That’s where I’ve heard of it before. And why it isn’t worth believing.

The general relativistic form of MOND is now called f ( r ) gravity, where the strength of gravity is chosen in an arbitrary and unscientific way. Plkanck searched for f ( r ) gravity and didn’t find it.

Speaking as one who has researched this subject in about as superficial way as is possible, your antipathy towards MOND seems unreasonable.

mollwollfumble said:

mollwollfumble said:

The Rev Dodgson said:

OK, I don’t recall seeing anything about emergent gravity here either.

> Entropic gravity provides the underlying framework to explain Modified Newtonian Dynamics, or MOND

That’s where I’ve heard of it before. And why it isn’t worth believing.

The general relativistic form of MOND is now called f ( r ) gravity, where the strength of gravity is chosen in an arbitrary and unscientific way. Plkanck searched for f ( r ) gravity and didn’t find it.

> From algebraic substitution of these into the above relations, one derives Newton’s law of universal gravitation:

But this is interesting, somewhat.

For starters, the first equation has a free constant (not shown). So in a sense we’re back-deriving this from Newton’s law of gravitation.

The insistence on assigning bits of information to Planck volumes first of all means that we have to get down to inaccessible lengths to see any deviation from Newton’s law of gravity. Do you see a problem with that?

Unruh radiation is iffy. It’s not particularly reliable.

Now, I can see how large hidden dimensions could lead to an increase in length scale making deviations from Newton’s law of acceleration accessible. But large hidden dimensions were searched for by the LHC and not found.

Although a replacement of Planck volumes by some other TOE such as loop quantum, superstrings or causal dynamical triangulation could lead to an emergent gravity, but only an emergent gravity that deviates from Newtonian gravity on scales too small to detect using current equipment.

What about the deviations from Newtonian gravity measured on the large scale, which have been detected?

The Rev Dodgson said:

mollwollfumble said:

mollwollfumble said:

> Entropic gravity provides the underlying framework to explain Modified Newtonian Dynamics, or MOND

That’s where I’ve heard of it before. And why it isn’t worth believing.

The general relativistic form of MOND is now called f ( r ) gravity, where the strength of gravity is chosen in an arbitrary and unscientific way. Plkanck searched for f ( r ) gravity and didn’t find it.

> From algebraic substitution of these into the above relations, one derives Newton’s law of universal gravitation:

But this is interesting, somewhat.

For starters, the first equation has a free constant (not shown). So in a sense we’re back-deriving this from Newton’s law of gravitation.

The insistence on assigning bits of information to Planck volumes first of all means that we have to get down to inaccessible lengths to see any deviation from Newton’s law of gravity. Do you see a problem with that?

Unruh radiation is iffy. It’s not particularly reliable.

Now, I can see how large hidden dimensions could lead to an increase in length scale making deviations from Newton’s law of acceleration accessible. But large hidden dimensions were searched for by the LHC and not found.

Although a replacement of Planck volumes by some other TOE such as loop quantum, superstrings or causal dynamical triangulation could lead to an emergent gravity, but only an emergent gravity that deviates from Newtonian gravity on scales too small to detect using current equipment.

What about the deviations from Newtonian gravity measured on the large scale, which have been detected?

You mean general relativity. No, they don’t come out of emergent gravity.

> Speaking as one who has researched this subject in about as superficial way as is possible, your antipathy towards MOND seems unreasonable.

I’m just sick of talking about it, again. MOND was disproved back in the 1980s with the incompatibility between gravity rotation curves and gravitational lensing by galaxy clusters. Disproved again with dwarf galaxies in general and the later with dwarf galaxies containing an excessive amount of dark matter. Then disproved again with the Bullet cluster. Then disproved for a fifth time with dwarf galaxies that contain no dark matter.

While MOND failed to exclude general relativity nobody bothered to take it seriously. Then it was rebranded as TeSv (or some similar name) variant of general relativity, and a few people started to take it seriously. Then it was rebranded a second time as f ( r ) gravity to hide its origins. Then it spawned hundreds of research papers, all conveniently forgetting that it had already been disproved five separate times by observations.

Superficial, no. I actually understand f ( r ) gravity.

mollwollfumble said:

> Speaking as one who has researched this subject in about as superficial way as is possible, your antipathy towards MOND seems unreasonable.

I’m just sick of talking about it, again.

OK

mollwollfumble said:

Superficial, no. I actually understand f ( r ) gravity.

I was talking about me, not you (reading it again, I see it doesn’t read like that, but that’s what I meant).

The Rev Dodgson said:

mollwollfumble said:

> Speaking as one who has researched this subject in about as superficial way as is possible, your antipathy towards MOND seems unreasonable.

I’m just sick of talking about it, again.

OK

mollwollfumble said:

Superficial, no. I actually understand f ( r ) gravity.

I was talking about me, not you (reading it again, I see it doesn’t read like that, but that’s what I meant).

Apologies. I didn’t understand. Also apologies for high horse, this thread is about entropic gravity, not MOND. I wonder if there’s a difference between emergent gravity and entropic gravity, the two match for Planck-scale counting, and quantum loop. But not for causal dynamical triangulation which may have an emergent gravity that isn’t entropic. I’m not sure.

Another observational disproof of MOND that I forgot to mention is the wiggles in the power spectrum of the cosmic microwave background. They predicted fewer wiggles than actually observed by Planck.

Fewer wiggles could only be a good thing (Four is already too many)

mollwollfumble said:

The Rev Dodgson said:

mollwollfumble said:

> Speaking as one who has researched this subject in about as superficial way as is possible, your antipathy towards MOND seems unreasonable.

I’m just sick of talking about it, again.

OK

mollwollfumble said:

Superficial, no. I actually understand f ( r ) gravity.

I was talking about me, not you (reading it again, I see it doesn’t read like that, but that’s what I meant).

Apologies. I didn’t understand. Also apologies for high horse, this thread is about entropic gravity, not MOND. I wonder if there’s a difference between emergent gravity and entropic gravity, the two match for Planck-scale counting, and quantum loop. But not for causal dynamical triangulation which may have an emergent gravity that isn’t entropic. I’m not sure.

Another observational disproof of MOND that I forgot to mention is the wiggles in the power spectrum of the cosmic microwave background. They predicted fewer wiggles than actually observed by Planck.

No apologies required – it did read like I was saying you knew nothing about it, rather than that I did.

I shall insert entropic gravity somewhere on my list of things to learn about.