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Offline Chemistry4me

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How does physics explain the graviton?
« on: 14/03/2009 09:30:39 »
How does physics explain the graviton?  ???
Can one of you clever people out there please tell me how physics explains the fact that when I let go of a ball, it falls to the ground? What on Earth is going on here? How does this (hypothetical?) graviton interact with the ball so that it falls to the ground?  ???


 

Offline lightarrow

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How does physics explain the graviton?
« Reply #1 on: 14/03/2009 10:57:32 »
How does physics explain the graviton? 
It doesn't. Infact gravitons don't exist.
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #2 on: 14/03/2009 10:59:40 »
Okay, so what happens? :)
 

Offline lightarrow

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How does physics explain the graviton?
« Reply #3 on: 14/03/2009 11:01:01 »
Okay, so what happens? :)
Do you mean why a ball falls to the ground?
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #4 on: 14/03/2009 11:01:30 »
Okay, so what happens? :)
Do you mean why a ball falls to the ground?
Yes.
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #5 on: 14/03/2009 11:03:36 »
Perhaps it is something that physics cannot explain just at this moment? :(
 

Offline lightarrow

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How does physics explain the graviton?
« Reply #6 on: 14/03/2009 11:15:21 »
Perhaps it is something that physics cannot explain just at this moment? :(
Why? It explains it from Newton; it's already several centuries! The last explanation I know is the one of GR: mass bends spacetime so the ball is forced to follow that bending.
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #7 on: 14/03/2009 11:15:52 »
I think I'm right in saying that the graviton only exists in Quantum Field Theory. It is basically postulated to make gravity work in the same way as the other known forces: i.e. by the exchange of guage bosons like the W & Z bosons of the weak force.

General Relativity says that objects move towards each other due to the curvature of space that is caused by the presence of matter (matter tells space how to curve and space tells matter how to behave). It doesn't however, give any indication as to how that curvature occurs.
« Last Edit: 14/03/2009 11:17:24 by DoctorBeaver »
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #8 on: 14/03/2009 11:20:49 »
mass bends spacetime so the ball is forced to follow that bending.

General Relativity says that objects move towards each other due to the curvature of space that is caused by the presence of matter (matter tells space how to curve and space tells matter how to behave).

So basically the ball falls to the ground because spacetime tells it to?
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #9 on: 14/03/2009 11:40:30 »
According to GR it doesn't "fall" at all. It tries to follow a geodesic.
 

Offline lightarrow

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How does physics explain the graviton?
« Reply #10 on: 14/03/2009 11:45:07 »
I think I'm right in saying that the graviton only exists in Quantum Field Theory. It is basically postulated to make gravity work in the same way as the other known forces: i.e. by the exchange of guage bosons like the W & Z bosons of the weak force.
Yes, but there is just a little problem: gravity is still not described by quantum mechanics...
Gravitons comes from a speculative "attempt" to describe gravity quantum mechanically, but it's actually illegitimate, in the absence of a real quantum theory of gravity.
« Last Edit: 14/03/2009 11:48:57 by lightarrow »
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #11 on: 14/03/2009 11:46:36 »
Hmmm... now I'm confused. ?????????
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #12 on: 14/03/2009 11:47:59 »
I think I'm right in saying that the graviton only exists in Quantum Field Theory. It is basically postulated to make gravity work in the same way as the other known forces: i.e. by the exchange of guage bosons like the W & Z bosons of the weak force.
Yes, but there is just a little problem: gravity is still not described by quantum mechanics...

I'm aware of that. Any theory that explains gravity will have to be more fundamental.
 

Offline lightarrow

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How does physics explain the graviton?
« Reply #13 on: 14/03/2009 11:49:51 »
You two write at the speed of sound! I couldn't edit my post that you already have written two of them!  :)
« Last Edit: 14/03/2009 11:52:40 by lightarrow »
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #14 on: 14/03/2009 11:54:19 »
You two write at the speed of sound! I couldn't edit my post that you already have written two of them!  :)

I may be ill but I can still type fast
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #15 on: 14/03/2009 11:56:03 »
Quantum physics is certainly not the final word
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #16 on: 14/03/2009 11:56:28 »
Hmmm... now I'm confused. ?????????

About what?
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #17 on: 14/03/2009 12:04:54 »
EVERYTHING!

And don't tell me that you're not!
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #18 on: 14/03/2009 12:08:34 »
I'm not confused by it. I know there are things about QM & gravity that I don't understand and that's it.
 

Offline Chemistry4me

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How does physics explain the graviton?
« Reply #19 on: 14/03/2009 12:12:26 »
Fine, I'll just go sulk in the corner.



 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #20 on: 14/03/2009 12:31:40 »
awwwww there there
 

Offline Vern

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How does physics explain the graviton?
« Reply #21 on: 14/03/2009 14:06:24 »
Gravity is an unusual critter when you try to fit it in with the other forces of nature. It is the weakest of the forces and yet can assemble the universe into structures we can barely imagine. Yet, there is a way to unite gravity and the electromagnetic forces that lets them reside comfortably in the same quantum governed universe.

The link is to Photonic Gravity in the New Theories forum. I just added a last paragraph to sum up the concept in one short paragraph, so I won't repeat it here.
 

Offline yor_on

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How does physics explain the graviton?
« Reply #22 on: 14/03/2009 14:50:36 »
How does physics explain the graviton?  ???
Can one of you clever people out there please tell me how physics explains the fact that when I let go of a ball, it falls to the ground? What on Earth is going on here? How does this (hypothetical?) graviton interact with the ball so that it falls to the ground?  ???

This is from a guy working in it :)

"Gravitons are closed strings. All strings can produce closed strings so all particles couple to gravity. Unlike other forces, which are related to open strings stuck to a brane, which limits the motion of the string ends, closed strings have no ends to stick to anything and therefore can move freely in any direction. This is the qualitative explanation of why gravity is so weak, it quickly dilutes itself through 10 dimensions, while photons are stuck to only spreading out in 3 dimensions. Strings, open or closed, can split and join so a closed string can 'pinch off' another closed string, which is two gravitons interacting."

And as I understand it it comes from QTF (Quantum field theory) The Standard model is another one of the theories collected under that umbrella. But in Standard Theory we didn't succeed to bind gravity to anything specific, when trying it only went to 'infinities',(gravitation is nonrenormalizable.) so we needed a new approach if we wanted to see gravity a a 'force' with its own 'carriers'. All the other forces we had succeeded in binding to particles, electromagnetisms to photons, the strong interaction to gluon's etc but not gravity. So there is where string theory comes in.

"Unlike the point particles (A point particle does not have any volume or surface area, it is zero dimensional) in quantum field theories like the standard model, strings interact in a way that is almost uniquely specified by mathematical self-consistency, forming an apparently valid quantum theory of gravity"

Looking at it mathematically it seemed very fitting apparently, although it creates a very weird universe at times:)

It all depends on how you see vacuum, if it only is a 'nothing',then where would the dips and heights of it be, gravitationally speaking? If it is something other, not an aether, but something holding in itself more than just a 'nothing', f ex, a 'matter-space symmetry' like I think at times, then I think it's possible to be satisfied with Einsteins description of it. But if it's a 'nothing' and gravity still behaves as it does, then we will have too look for an extraneous force like gravitons. Maybe I'm wrong, but that's how I see it.
 

Offline Vern

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How does physics explain the graviton?
« Reply #23 on: 14/03/2009 20:56:53 »
That looks like string theory yor_on. I think there is five or six versions out there now. Then there's the M theory that tries to combine all the string theories as sub-sets of itself. Now I see a lot of attention being given to Many Worlds Theory. In MWT all possible happenings occur simultaneously in multiple universes.

I kinda hope that none of those really catch on enough to garner a seizable portion of the available funding. My chances of understanding enough about any of those to make sense of them is small. :)
 

Offline DoctorBeaver

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How does physics explain the graviton?
« Reply #24 on: 14/03/2009 22:56:18 »
Vern - don't forget 10-dimensional supergravity!
 

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How does physics explain the graviton?
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