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Is gravity just entropy rising? Long-shot idea gets another look

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Re: Is gravity just entropy rising? Long-shot idea gets another look

#271

Post by quantadev »

amy214 wrote: post #267
quantadev wrote: post #230

Earlier quoted context omitted.

Gravity doesn't interact, other than to simply set the shape of the spacetime in which particles move.

It's also worth pointing out gravitation waves are a thing (have been detected by LaWD or Laser Wave of Gravitation Detector). Does not mean it's not changing the spacetime shape, indeed, these are a type of ripple in spacetime as might occur if Sally Struthers did a jumping jack.

Yes, by "the shape of spacetime" that refers to every specific location in spacetime having a specific shape associated to it. It you want to expand your view out across a range of space and/or time, yes you can see waves, but those waves are still nothing but just waves of variations in "the shape of spacetime". Because we haven't proven the existence of a graviton yet.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#272

Post by Ma8ee »

fc417fc802 wrote: post #226
Ma8ee wrote: post #207

Earlier quoted context omitted.

Entropy is certainly a physical “thing”, in the sense that it affects the development of the system. You can equally well apply your argument that it isn’t a physical thing because it doesn’t exist on a microscopic scale to temperature. Temperature doesn’t exist when you zoom in on single particles either. There’s no reason to involve our knowledge of the system. Entropy is a measure of the number of possible micro s…

Exactly! Temperature isn't fundamental. It's a statistical measure made up by humans. It's certainly a very useful abstraction but it isn't a fundamental property. It describes an emergent pattern observed in larger systems. Same for entropy (and also AFAIK angular momentum). It's entirely possible I'm wrong about any of the above but if so I've yet to encounter a convincing line of reasoning.

With the same line of reasoning you can argue (and some have) that numbers aren’t fundamental and are only made up by humans. In my view, the number of swans in the pond is three whether humans exist or not.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#273

Post by nearbuy »

meindnoch wrote: post #49
prof-dr-ir wrote: post #36

Earlier quoted context omitted.

Good question. You are absolutely right that entropy is always fundamentally a way to describe are our lack of perfect knowledge of the system [0]. Nevertheless there is a distinct "reality" to entropic forces, in the sense that it is something that can actually be measured in the lab. If you are not convinced then you can look at: https://en.wikipedia.org/wiki/Entropic_force and in particular the example that is alw…

Sure, I'm not denying that entropy exists as a concept, that can be used to explain things macroscopically. But like you said, it's origins are statistical. To me, temperature is also a similar "made up" concept. We can only talk about temperature, because a sufficiently large group of particles will converge to a single-parameter distribution with their velocities. A single particle in isolation doesn't have a tempe…

When you go deeper into physics, mass and energy don't seem real either, in that, like entropy, they're emergent properties of a system rather than fixed, localized things.

I always thought of the energy of a system (kinetic + potential) as a useful mathematical invariant that helps us predict systems rather than a physical thing. If you put a cart at the top of a hill, then the cart has more potential energy (but only from certain reference frames). It doesn't feel like that potential energy is physical. It doesn't have a specific location; it's a property of the whole Earth-cart system. And yet, it's this total energy that gives rise to the physical properties we're familiar with. In fact, almost all of the mass in your body comes not from the mass of elementary particles, but from the potential energy in the bonds between quarks. Your mass is more than 99% from potential energy.

And then when you get into Quantum Field Theory, it turns out particles (like electrons) are no longer truly point particles but rather another emergent phenomenon from ripples in an underlying field. A particle is just a model that describes it well when looked at from a distance. (I hope I'm not butchering that, as I'm not a physicist.)

So mass, matter, energy, and entropy are all emergent properties of a system rather than being localized, "real" things in the way we'd intuitively think. And at that point, I'm not sure how we would define "real" or why it would be a useful distinction. Is there a useful insight to be gained by putting entropy in a different category of realness than mass?

Re: Is gravity just entropy rising? Long-shot idea gets another look

#274

Post by cryptonector »

raattgift wrote: post #264
cryptonector wrote: post #135

Earlier quoted context omitted.

You have it backwards. The lowest entropy state of the universe would be if there were no attractive forces, only repellent forces, as then all particles would be forced into something of an expanding lattice, but with all particles equidistant from all nearest neighbors (of the same type). It is gravity which disrupts this and causes clumping, and that _increases_ entropy. I know it's confusing because normally one…

If everything must be constrained to the lattice points, yes. However, empty space has high Boltzmann entropy: you can cut a patch of empty space from here and swap it for the same volume of empty space from there, and the two coarse grain macrostates will be indistinguishable. Expanding de Sitter quasi-vacuum has tremendous growth in entropy. Gibbons and Hawking gives this (for 3+1d de Sitter) as a quarter of the ho…

If you consider a universe with only protons in it initially clearly they would all be forced into a low-entropy lattice and space would expand. Eventually the space between them would grow to be sufficiently large and empty that its own entropy would be enormous. But that doesn't deny that gravitational collapse is an entropy-increasing mechanism.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#275

Post by boombadabig »

the__alchemist wrote: post #149
pif wrote: post #40

As an experimental physicist, I refuse to get excited about a new theory until the proponent gets to an observable phenomenon that can fix the question.

This is why I'm skeptical of theories like Wolfram's: It feels like an overfit based on this: It produces all sorts of known theories (special relativity, parts of QM, gravity etc), but doesn't make new testable predictions, or new fundamentals. When I see 10 predictions emerge from the theory, and they all happen to be ones we already known of... Overfit.

[dead]

Re: Is gravity just entropy rising? Long-shot idea gets another look

#276

Post by fc417fc802 »

Ma8ee wrote: post #272
fc417fc802 wrote: post #226

Earlier quoted context omitted.

Exactly! Temperature isn't fundamental. It's a statistical measure made up by humans. It's certainly a very useful abstraction but it isn't a fundamental property. It describes an emergent pattern observed in larger systems. Same for entropy (and also AFAIK angular momentum). It's entirely possible I'm wrong about any of the above but if so I've yet to encounter a convincing line of reasoning.

With the same line of reasoning you can argue (and some have) that numbers aren’t fundamental and are only made up by humans. In my view, the number of swans in the pond is three whether humans exist or not.

I think that's conflating distinct concepts. Numbers aren't a physical property. Whether or not they're a fundamental concept is largely a philosophical question.

Meanwhile temperature (for example), while physical, is a statistical property of a macroscopic system. It isn't fundamental - rather it's an abstraction over a (very) large set - but it is nonetheless a quantification of physical characteristics. Whereas a number, for example 2 rocks, is not quantifying any physical property of the individual rocks themselves.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#277

Post by buggyipadmettoo »

aeonik wrote: post #236
buggyipadmettoo wrote: post #231

Earlier quoted context omitted.

Just swap out "my take, for what it's worth" For "according to ChatGPT"

I don't like your comment, it's pretty low effort, and your tearing down a lot of effort that I have put into learning about physics and entropy over the years. I came up with the psuedonym Aeonik Chaos circa 2010 because my studies of Chaos Theory and Entropy left a very deep impact on me. I've been thinking about entropy ever since my dad, a biochemist, embryologist, and doctor told me he thought that entropy was b…

I know it seems low effort but I spent a good ten minutes reading through your other comments looking for an explanation for your post. It reads as so obviously written by an LLM.

I have no doubt you're a real person, and that all those things you claim are true. Almost all of your posts are clearly written by a thoughtful human.

But then I see that occasionally, you post something that looks nothing like your other posts, and exactly like it was written by an LLM. I love learning from ChatGPT too, but I'm curious about your mindset if and when you have it speak for you here. Is the goal to use ChatGPT to educate us? If so, why not give it credit?

Everyone here knows how to use google and ChatGPT (and a majority of us could whip up a script to auto-post LLM responses). It seems like most of the internet is already "dead".. don't give it HN too, please, stick to posting thoughtful human stuff!

Re: Is gravity just entropy rising? Long-shot idea gets another look

#278

Post by aeonik »

buggyipadmettoo wrote: post #277
aeonik wrote: post #236

Earlier quoted context omitted.

I don't like your comment, it's pretty low effort, and your tearing down a lot of effort that I have put into learning about physics and entropy over the years. I came up with the psuedonym Aeonik Chaos circa 2010 because my studies of Chaos Theory and Entropy left a very deep impact on me. I've been thinking about entropy ever since my dad, a biochemist, embryologist, and doctor told me he thought that entropy was b…

I know it seems low effort but I spent a good ten minutes reading through your other comments looking for an explanation for your post. It reads as so obviously written by an LLM. I have no doubt you're a real person, and that all those things you claim are true. Almost all of your posts are clearly written by a thoughtful human. But then I see that occasionally, you post something that looks nothing like your other…

I use it to edit some of my posts, and clean up grammar, or to help articulate thoughts that I don't have time to give a proper third or fourth pass to.

I'm very busy these days, and will often use ChatGPT as an editor.

I'll often drop a rough draft into ChatGPT and have it clean it up, or ask or for other perspectives I might be missing.

For the comment in question, I had a spidey sense activated from the conversation. And ChatGPT helped me narrow my focus down to the different levels that entropy apply to, though I had push back on it a bit before it got to the meat of my thoughts.

I think of it as a sort of translator, it helps communicate vibes that the Striatum part of my brain is feeling/sensing, but that the verbal or symbolic part of my brain hasn't figured out to say or express yet.

Normally this process can take a while, and ChatGPT remarkably speeds this cycle up, at least for me.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#279

Post by Gravityloss »

kgwgk wrote: post #266
Gravityloss wrote: post #263

Earlier quoted context omitted.

The point is that the gravity interactions are time reversible. Not so with friction etc.

Sure, nothing in the laws of physics prevents a celestial body from distancing itself from the Sun or from the Moon. But it would like suspicious! Wouldn't you suspect that you were watching a reversed video?

You don't understand my point. If we watch purely gravity interactions, the video can be reversed and you wouldn't be able to detect it.

If a meteor crashes into the moon, there's other effects than gravity that makes the video not reversible. Ie it's not only gravity.

That's the point.

In other words, if a comet approached the moon at high speed, missed and slingshotted in another direction, it would be traveling away from the moon, but the video would be time reversible and you couldn't be able to detect it. Gravity only interaction.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#280

Post by sim7c00 »

jvanderbot wrote: post #169
sim7c00 wrote: post #164

Earlier quoted context omitted.

but these nuts move by gravity do they not? and what in the universe is exactly up and down? and why would that matter? are all celestial bodies then a local up and 'away from them' down? this analogy hurts my brain. please tell me how to make the hurting stop

You need to reread the middle only. It's a kind of "vacuum" effect.

but where in nature is then this vacuum? is it just higher and lower energy density or something? like high and low pressure systems in weather pushing and pulling?

that would or might imply gravity is electromagnetic?

(sorry if this seems really off the charts / missing your point!)

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