Gravity & interference

[Boerseun]

Okay - another stupid question:

 

The supposed existence of gravitons as the massless particle that carries the gravitational force, implies that without that particle being there, no gravity would be experienced.

 

As far as I can see, the graviton is rather analogous to the photon, massless, its own antiparticle, etc.

 

Sooooo... can gravitons experience destructive interference, like photons? Can there be gravitational interference patterns? And if there are such interference patterns, there should be zero gravity (inside the destructive pattern, of course) even right at the surface of a black hole (?).

[Qfwfq]

Good question!

can gravitons experience destructive interference, like photons? Can there be gravitational interference patterns?

Presumably. Actually, certainly. Providing the right situation arises, which I have a few doubts about.

 

And if there are such interference patterns, there should be zero gravity (inside the destructive pattern, of course) even right at the surface of a black hole (?).

First, destructive interference would have to occur there, not very likely. Further, it would have to occur for all gravitons that could otherwise get there.

[UncleAl]

The graviton is a mathematical construct, a spin-2 tensor boson. There is no evidence that it exists and considerable reason to doubt that gravitation is quantized by whatever means. Can you quantize sound being conducted through air? No. As has been posted before,

 

thermodynamics + Bekenstein bound = General Relativity

 

That gravitation is pure geometry argues against there being any virtual propagating particle associated with it unless you can quantize geometry itself. Emission of gravitational waves has quadrupole symmetry, as opposed to EM phenomena with dipole symmetry. There is no easy way to emit intense coherent (or otherwise) gravitational radiation of short wavelength except by collapsing stars or tighty orbiting neutronium.

 

http://arXiv.org/abs/astro-ph/0401086

http://arxiv.org/abs/astro-ph/0312071

http://relativity.livingreviews.org/Articles/lrr-2003-5/index.html

 

As gravitation cannot be shielded or diverted, you need a new view of interferometery (e.g., LIGO).

[Boerseun]

I was thinking along those same lines, Uncle - I think using interference patterns is actually a neat way to disprove gravitons.

[infamous]

 

That gravitation is pure geometry argues against there being any virtual propagating particle associated with it unless you can quantize geometry itself.QUOTE]

 

This geometric concept for the nature of gravity is, at least for me, a very good position to take on the subject. I'm aware that there are many theorists in the scientific community today that also take this view. Even so, there remain others that hold to the notion for the existence of these so-called gravitons.

 

If I may make an observation at this juncture:

 

I view Gravity with the same esteem as do Entropy with this one exception. Entropy is the direction which time is traveling toward a state of disorder. On the other hand, Gravity is the direction which time is traveling toward a state of order. This may be entirely to simple an explanation for the differences between the two. However, because science knows so little about the true nature of both entities, this description may not be too far from the truth.

[Boerseun]

Entropy is the direction which time is traveling toward a state of disorder. On the other hand, Gravity is the direction which time is traveling toward a state of order.

Interesting...

 

If you run time forwards, gravity is an attractive force. If you run time backwards, gravity pushes away. The direction gravity works in, depends on the direction time is flowing in... are they linked, or am I jumping to conclusions here?

[infamous]

Interesting...

 

If you run time forwards, gravity is an attractive force. If you run time backwards, gravity pushes away. The direction gravity works in, depends on the direction time is flowing in... are they linked, or am I jumping to conclusions here?

My point is Boerseun: Gravity and Entropy working within the same framework of time are in eternal competition. If time were reversed as you suggest, Gravity would still exist along with Entropy, they would just switch places with respect to how they act.

[Boerseun]

I did see your point, infamous - I was just flying off on a different tangent there for a moment...

[infamous]

I did see your point, infamous - I was just flying off on a different tangent there for a moment...

Ofcourse then, we are on the same page. Sadly, at the moment I have no proof of this theory. It is however, as you've already stated,"interesting" and I will continue to search out these possibilities.

[CraigD]

... can gravitons experience destructive interference, like photons? ...

If the graviton actually exists, then, like all the Standard Model particles, each has a wave function, so it should in principle be possible to construct an interference pattern.

 

A couple of problems, though:

1) how would you arrange to have gravitons interfere? Unlike a photon or fermion, no one knows how to absorb or emitted one in a specific direction, so I can’t imagine any way to creating the 2 virtual paths you’d need to create an interference pattern

2) if you could get them to interfere, how would you measure it? The graviton interaction is so weak that I can imagine no way to measure individual or localized collections of them that would rise above the “noise” of other interactions associated with any particles that could be used to measure it. The best near-term gravity detectors, such as the LIGO, will be lucky to detect the equivalent of vast numbers of gravitons associated with events like supernovae and neutron star collisions.

 

I think these difficulties are one of the reasons particle physicists are so reluctant to include the graviton in the standard model – the difficulty of designing an experiment to detect it is so high that it’s nearly a non-scientific theory. A particle true believer can get past the many compelling classical (gravity is pure geometry) and statistical (thermodynamic) objections, but the frustrating inability to construct a confirming/falsifying experiment is almost too much.

 

The only experiment I can think of is awesomely outlandish, involving a device something like the Cavendish experiment, but using black holes in place of lead spheres. Not exactly science fair material.

[CraigD]

… Entropy is the direction which time is traveling toward a state of disorder. On the other hand, Gravity is the direction which time is traveling toward a state of order. …

This only works if a lower gravitational potential energy – a “fallen together” – system has lower entropy than a higher one. I don’t think it does.

 

For small masses, the collision of all the stuff falling together into a central pile will generate a lot of heat, increasing entropy. To chill it down to get a nice, neat, low-entropy homogenous sphere, like I think you’re visualizing, you have to eject a lot from the system. This is thermodynamic cheating – you can always decrease the entropy of part of a system by increasing it in another part.

 

If you accept the old dictum that “black holes have no hair”, that is, that the only info you can get from a black hole is its mass, angular momentum, and charge, the gravity vs. entropy idea works. I believe that view is obsolete, though, and that theorists like Steven Hawking have pretty much convinced everybody that black holes are plenty hairy, warty, etc.

[infamous]

 

If you accept the old dictum that “black holes have no hair”, that is, that the only info you can get from a black hole is its mass, angular momentum, and charge, the gravity vs. entropy idea works. I believe that view is obsolete, though, and that theorists like Steven Hawking have pretty much convinced everybody that black holes are plenty hairy, warty, etc.

I understand this perspective CraigD, and I do not disagree with it. Black holes could be as hairy as Big Foot himself, this point does not however eliminate what I call this competition between Entropy and Gravity. We must recognize that within the same time frame both faculties are at work, in our present universe Gravity and Entropy coexist. Likewise with respect to these hairy Black holes, both Gravity and Entropy are at work simultaneouly. Neither can gain the complete upper-hand over the other. At one time or another, one may have the advantage over the other but never is either one in complete dominance over the other. Never will Gravity overcome Entropy by 100% and likewise the reverse is also true. The only case where this is not true would be before the Big Bang itself, where Entropy was nonexistent. What we don't know is weather Gravity was also nonexistent, everso, that Gravity existed before the Big Bang is more likely than the case for Entropy by a huge margin.

[vipa]

hi and good day to you

 

vipa here

just your post on grv and iotofericon

 

yes grv is there

i would like to give food for thought

 

grv is = - and the sun = +

all things are of this base

to set up a trap all you need is a rock tha is 330 lb

set in a way to make the right connection with the - and using a there called dopping

press + to = - and you will have a trap

 

this is how the tunamcommen people did it

 

vipa

[infamous]

hi and good day to you

 

vipa here

just your post on grv and iotofericon

 

yes grv is there

i would like to give food for thought

 

grv is = - and the sun = +

all things are of this base

to set up a trap all you need is a rock tha is 330 lb

set in a way to make the right connection with the - and using a there called dopping

press + to = - and you will have a trap

 

this is how the tunamcommen people did it

 

vipa

I havn't got a clue what all this gibberish is supposed represent? Please try again vipa, your sentence structure and ideas are unintelligible.

[Erasmus00]

I view Gravity with the same esteem as do Entropy with this one exception. Entropy is the direction which time is traveling toward a state of disorder. On the other hand, Gravity is the direction which time is traveling toward a state of order. This may be entirely to simple an explanation for the differences between the two. However, because science knows so little about the true nature of both entities, this description may not be too far from the truth.

 

While the argument could be made that little is known about gravity, personally I believe general relativity demonstrates a pretty remarkable knowledge. Besides that, I don't think you cna claim that science knows very little about entropy. Entropy is a very concrete thermodynamics concept, defined by the multiplicity. I don't want to go into a thermodynamics/stat. mech lecture, but entropy has been pretty well nailed down since Boltzman.

-Will

[infamous]

While the argument could be made that little is known about gravity, personally I believe general relativity demonstrates a pretty remarkable knowledge. Besides that, I don't think you cna claim that science knows very little about entropy. Entropy is a very concrete thermodynamics concept, defined by the multiplicity. I don't want to go into a thermodynamics/stat. mech lecture, but entropy has been pretty well nailed down since Boltzman.

-Will

I must agree with your statements here Erasmus00, I was a little hasty to include Entropy into the category of the unexplained. Even though there are still questions about why Entropy only travels in one direction of time, it is a rather well researched and documented law of nature. I must confess that I was too eager to present my point of view with regard to the connection that I believe exists between these faculties of nature.

[Little Bang]

Boerseun, I am in shock, I can't give you answer but your question is far stupid, one of the best that anyone has asked. I'll have to give this a lot of thought.