How does gravity work?

How does science work? And what's all this about quantum mechanics?

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uwot
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Re: How does gravity work?

Post by uwot »

Cerveny wrote: Sun Aug 27, 2017 7:32 pmGTR works quite well, but it cannot explain "dark" matter and it cannot be quantized.
Well, it's because the field equations are so accurate that dark matter was postulated in the first place. The maths works very well; it's the model of two separate substances, space and matter/energy, which is less convincing. As any philosopher knows, the problem with dualism is that you ought to explain the mechanism by which the two things interact. There is no such explanation in general relativity. As I said in the opening post, I think that refraction is a plausible mechanism; you can judge for yourself here: http://willijbouwman.blogspot.co.uk
Cerveny wrote: Sun Aug 27, 2017 7:32 pmAnd for example such shift of Mercury trace has been exactly (the same expression) computed by clasical way by, I think, Paul Gerber...
You mean with Newtonian physics? I know there are attempts at Modified Newtonian physics, but I'm not enough of a mathematician to know whether this just means adding variables to the inverse square law; in a way analogous to the addition of epicycles to the Ptolemaic model.
Dubious
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Re: How does gravity work?

Post by Dubious »

Maybe the space inside a balloon (the universe) is different from that which is external to it causing a space-time matrix as a type of voltage difference which bends and warps due to energies present on the inside. Maybe the universe operates as a kind of giant battery which gradually erodes through entropy.

...just babbling my own speculations which are obviously more metaphoric than scientific.

When speaking of "space" it appears we are not only referring to ONE thing since space beyond 3 dimensions (not including time) has already been hypothesized and that THIS universe may be a derivative of the next higher dimension. When something derives from something higher, is that "difference" lost in the "step-down" transformation or simply changed into some other form as a necessary ingredient to its creation?

Again, just rhetorical speculations!
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PauloL
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Re: How does gravity work?

Post by PauloL »

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We can't ignore Hegel's pearls when discussing gravity, which can be of great help here.

Nach Hegel, gravity reveals itself as the true concept of matter:

Through the moment of its negativity, of its abstract separation into Vereinzelung, matter holds itself asunder in opposition to its self-identity; this is the repulsion of matter. But since these different parts are one and the same, matter is no less essentially the negative unity of this sundered being-for-self and is therefore continuous; this is its attraction. Matter is inseparably both and is the negative unity of these two moments, individuality. But this individuality as still distinguished from the immediate asunderness of matter and consequently not yet posited as material, is an ideal individuality, a Mittelpunkt: GRAVITY.
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Hobbes' Choice
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Re: How does gravity work?

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uwot wrote: Wed Feb 22, 2017 12:18 pm In a word: refraction. Details in the usual place: http://willijbouwman.blogspot.co.uk
Gravity does not "work". It is a descriptor by which humans condense a set of appearances that reflect a property of reality.
Matter has a tendency to move towards other matter. That is it. There is no explanation. It's just a fact. You can dress it up with as much description and detail as you like; it matters not what you call it; its just like it is.
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Arising_uk
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Re: How does gravity work?

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PauloL wrote: Mon Aug 28, 2017 1:16 pm .We can't ignore Hegel's pearls when discussing gravity, which can be of great help here.

Nach Hegel, gravity reveals itself as the true concept of matter:

Through the moment of its negativity, of its abstract separation into Vereinzelung, matter holds itself asunder in opposition to its self-identity; this is the repulsion of matter. But since these different parts are one and the same, matter is no less essentially the negative unity of this sundered being-for-self and is therefore continuous; this is its attraction. Matter is inseparably both and is the negative unity of these two moments, individuality. But this individuality as still distinguished from the immediate asunderness of matter and consequently not yet posited as material, is an ideal individuality, a Mittelpunkt: GRAVITY.
No I really think we can ignore safely ignore this as of being no help whatsoever.
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PauloL
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Re: How does gravity work?

Post by PauloL »

Can you discuss gravity ignoring pure elegantly philosophical approaches like Hegel's?
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Arising_uk
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Re: How does gravity work?

Post by Arising_uk »

What is it you think his metaphysics has explained about gravity?
uwot
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Re: How does gravity work?

Post by uwot »

Hobbes' Choice wrote: Mon Aug 28, 2017 4:11 pmGravity does not "work". It is a descriptor by which humans condense a set of appearances that reflect a property of reality.
Matter has a tendency to move towards other matter. That is it. There is no explanation. It's just a fact. You can dress it up with as much description and detail as you like; it matters not what you call it; its just like it is.
There are plenty of physicists who are actively trying to discover the mechanism that produces matter's "tendency to move towards other matter." It is true that there is no consensus; some people are content with Einstein's model of warped spacetime; others think it might be the exchange of particles called gravitons and there is a whole raft of other hypotheses. It is also true that the fact that we don't understand the mechanism is no impediment to our using Newton or Einstein as mathematical descriptors, but our not understanding the mechanism, doesn't mean there isn't one. What you are suggesting is a 'spooky action at a distance' of the gaps. That or Aristotelian teleology.
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Hobbes' Choice
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Re: How does gravity work?

Post by Hobbes' Choice »

uwot wrote: Mon Aug 28, 2017 5:11 pm
Hobbes' Choice wrote: Mon Aug 28, 2017 4:11 pmGravity does not "work". It is a descriptor by which humans condense a set of appearances that reflect a property of reality.
Matter has a tendency to move towards other matter. That is it. There is no explanation. It's just a fact. You can dress it up with as much description and detail as you like; it matters not what you call it; its just like it is.
There are plenty of physicists who are actively trying to discover the mechanism that produces matter's "tendency to move towards other matter." It is true that there is no consensus; some people are content with Einstein's model of warped spacetime; others think it might be the exchange of particles called gravitons and there is a whole raft of other hypotheses. It is also true that the fact that we don't understand the mechanism is no impediment to our using Newton or Einstein as mathematical descriptors, but our not understanding the mechanism, doesn't mean there isn't one. What you are suggesting is a 'spooky action at a distance' of the gaps. That or Aristotelian teleology.
On the contrary. Those who insist on a distinct force of "gravity", are suggesting a teleology. My take on it is quite the opposite.
In fact your language demands that teleology. When you say "we don't understand the mechanism", you are implying that there is a distinct mechanism whose purpose is to make things fall. I'm simply saying that the entire idea of "gravity" is a human interested narrative in which the universe is seen as a designed set of interactions that have a job to do.

We can never know what the universe is really like, though we can extend our perception of it with clever machines, all these show is that we have a very idiosyncratic and partial view of reality and gravity is among the limited conception. Gravity is over important since humans are pissed off about falling over and hurting themselves, or falling out of the trees where we, not long ago used to live.

The question should be more like. What are the things about the universe that urge us to take an interest in what we like to call gravity. The universe does not give a damn about gravity and does not recognise it as any kind of discrete force. What Einstein hints at is that it is but one aspect of the fabric of reality but not distinct from it, part of space/time and not a part from it. But by such things humans are err to categorise, and reduce.
uwot
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Re: How does gravity work?

Post by uwot »

Hobbes' Choice wrote: Mon Aug 28, 2017 5:46 pmThose who insist on a distinct force of "gravity", are suggesting a teleology. My take on it is quite the opposite.
In fact your language demands that teleology. When you say "we don't understand the mechanism", you are implying that there is a distinct mechanism whose purpose is to make things fall.
Well, I wouldn't claim there is any purpose. What we know is, as you said, "Matter has a tendency to move towards other matter", although on cosmic scales, we rather think that matter has a tendency to move away from other matter. Still, on Earth at least, things fall to the ground. As far as I can tell your response is 'They just do.' Fair enough. Some physicists are instrumentalists and don't particularly care if there is a mechanism; Newton famously would frame any hypotheses. Others, including Einstein, think it might be worthwhile trying to work out whether there is.
Hobbes' Choice wrote: Mon Aug 28, 2017 5:46 pmI'm simply saying that the entire idea of "gravity" is a human interested narrative in which the universe is seen as a designed set of interactions that have a job to do.
Gravity is just the name given to the force that demonstrably exists between two or more bodies. If ever a cause of gravity is discovered, I don't imagine the name will change.
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HexHammer
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Re: How does gravity work?

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uwot wrote: Wed Feb 22, 2017 12:18 pmIn a word: refraction. Details in the usual place: http://willijbouwman.blogspot.co.uk
Pure nonsense and babble! No one knows exactly how gravity works, but least Einstein said that it has unlimited range.
uwot
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Re: How does gravity work?

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HexHammer wrote: Mon Aug 28, 2017 9:45 pm
uwot wrote: Wed Feb 22, 2017 12:18 pmIn a word: refraction. Details in the usual place: http://willijbouwman.blogspot.co.uk
Pure nonsense and babble!
Ah well; at least it's consistent.
HexHammer wrote: Mon Aug 28, 2017 9:45 pmNo one knows exactly how gravity works...
True.
HexHammer wrote: Mon Aug 28, 2017 9:45 pm...but least Einstein said that it has unlimited range.
And until the expansion of the universe was found to be accelerating, most people agreed with him.
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PauloL
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Re: How does gravity work?

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UW your site looks truly awesome for people searching for basic knowledge in physics. Very didactic and easy to follow. I'm impressed.
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PauloL
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Re: How does gravity work?

Post by PauloL »

uwot wrote: Mon Aug 28, 2017 10:01 pm And until the expansion of the universe was found to be accelerating, most people agreed with him.
Do you mean gravity doesn't follow universe's expansion?
uwot
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Re: How does gravity work?

Post by uwot »

PauloL wrote: Mon Aug 28, 2017 10:06 pm
uwot wrote: Mon Aug 28, 2017 10:01 pm And until the expansion of the universe was found to be accelerating, most people agreed with him.
Do you mean gravity doesn't follow universe's expansion?
Well, all I really mean is that, on the intergalactic scale, the measurement of red-shift implies that there is a force (dark energy) which overcomes the force of gravity.
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