Gravitons?

[firewolfsm]

Another idea/question I had recently, this time about the gravitons that we haven't actually discovered yet.

I think that because every other force we know can only propagate through wave-particles, we assume the same for gravity (we also assume it's quantized but that's a different topic). If gravitons travel at the speed of light or less, then one would expect them to experience the same gravitational effects. That's the odd part I guess, why should they feel gravity if they're the source of the effect...I'm not really sure at this point but an object has a gravitational field and gravitons still have to pass through it.

If light can't escape a black hole, why should gravitons?

I thought about this and came up with 5 or 6 half-assed answers to the question but they all have flaws at some point. I think the only explanation is that gravitons are either a) not bosons (as theorized) and introduce some new fundamental particle or b) don't exist, and gravity is a different kind of force and has no waves.

 

[bwanaaa]

I too have thought about this conundrum. Gravity is also different in another way. The other fields we commonly measure (electricity and magnetism) have positive and negative (or north and south) qualities. This dichotomy has not been observed as commonly with gravity. One would think that antigravity would have been used to explain some of the ethereal phenomena observed in the universe. I guess that's why gravitons are described as a monopole-although i dont really know where that fits in the taxonomy of elementary particles. How would one arrange quarks to get a monopole? I cannot seem to recall the differences of bosons and the other particle types (baryons, mesons, etc.) but do remember that quark arrangements could account for them. But nowhere in the zoo of particles was an array of quarks to define a graviton described.

As to the black hole problem- was it not Hawking that speculated on black hole radiation- ?Which begs the question of how things escape black holes.

But i suppose you could postulate that gravitons have even less energy than photons. Therefore, the gravity required to prevent their escape is not great enough at the surface of the black hole. But at some point within the black hole, the gravity is great enough for this phenomenon to occur and as a result, all the mass of the black hole exists at this boundary layer. In effect, the black hole should be hollow. The location of the boundary layer marks the points where gravity is so great that gravitons do not escape. Everything inside of that layer would not experience gravity and would therefore fly outwards until it met the boundary layer. You would then have black hole stuff (plasma?) until the outer surface. Fun to think about but no way to know.

 

[firewolfsm]

Hawking radiation is a quantum effect that's not really related to this.

Also, aren't black holes just stars? They shouldn't be hollow or any different from most stars, it's radius to mass ratio will be past a certain limit though. Gravitational fields always start at the center of an object.

And I thought about that, but it doesn't matters how much energy gravitons have, space around black holes is infinitely curved, that's the real reason light can't escape.

also, look up the particle types on wikipedia, people think gravitons will be bosons like a lot of other particles out there right now.

 

[Throckmorton]

I don't know anything about gravitons but radiation from a black hole comes from the event horizon IIRC, not inside the event horizon. The event horizon is the sphere around the black hole beyond which mass and energy can't escape

 

[Jeff7]

Concerning the apparent lack of polarity of gravity, what about this repulsive "dark energy" force I hear about? Might it be some sort of manifestation of gravity's opposite polarity?
We can perceive a magnet's polarity easily, in three dimensions. Gravity's attractive force is directed toward the center of a 3-dimensional object. The other "side" would only show up very far away from the body, and would seem quite weak from spreading out so much.

Though I envision it, in my relatively uneducated mind where such things are concerned, as space repelling itself, much like particles within a gas will repel each other, causing the collective quantity of gas to expand. Space itself could be repelled from itself, trying to expand to fill whatever "volume" lies beyond our universe's little bubble.


I wonder where theoretical physics will be in another hundred years. Advanced technology hasn't been around too long, but now that it's here, the rate of growth and improvement is incredibly rapid. It will be interesting to see what mathematical tools we'll have available, too - things like quantum or optical supercomputers that would could out-compute the summation of all of the computers in existence today. With them would come simulations which would need to take fewer mathematical shortcuts, while still running in a reasonable timeframe.

 

[TastesLikeChicken]

I tend towards b) - gravity is a different kind of force and has no waves - because if gravity did have a wave function we should have directly detected gravitational waves by now...and we haven't. Maybe we don't have enough resolution in our detectors yet, but if the next gen of detectors coming online don't show anything it may be time to reconsider a few things about gravity.

 

[silverpig]

Photons are waves in the EM field. Gravitons should be waves of space. Because gravity is so weak compared to EM the waves are beyond our ability to detect right now.

 

[KIAman]

Maybe gravity does have an opposite, in another universe. Maybe our universe is the "positive" and there is another mirror univierse "negative" and our mutual opposite gravity polarity attracts each other thus our sensation of gravity.

Black holes could be explained as the link between our bi polar universe and is the the gravity "neutral." This way, our respective universe can continually expand at an accelerating pace while still have the potential to "link" up with our opposite universe to start the big bang all over again.

Wow, enough brain dribble for me.

 

[firewolfsm]

SO

I asked Dr. Muller himself, and he said that gravity is released at the Schwarzschild radius

http://en.wikipedia.org/wiki/Schwarzschild_radius

which basically answers my question. Back to graviton theory!

 

[JSSheridan]

Originally posted by: firewolfsm
Hawking radiation is a quantum effect that's not really related to this.

Also, aren't black holes just stars? They shouldn't be hollow or any different from most stars, it's radius to mass ratio will be past a certain limit though. Gravitational fields always start at the center of an object.

And I thought about that, but it doesn't matters how much energy gravitons have, space around black holes is infinitely curved, that's the real reason light can't escape.

also, look up the particle types on wikipedia, people think gravitons will be bosons like a lot of other particles out there right now.

I know that it's widely accepted that space is infinitely curved at a singularity, but how do we know it is not finite and has not just distorted that area of space to be much much larger than we know the universe to be? If this is the case, light from the one side of the singularity would not have had time to reach an observer on the other side. If the distortion were increasing in size at a greater rate than the speed of light, then light would never "escape".

I don't know if I'd call a black hole a star, since it's unlikely and nuclei are being fused. It's certainly formed from a star as far as we know. It's just a very small point where a finite amount of mass is located that may or may not have an electric charge and angular momentum. Because the black hole is so small, the angular velocity is probably very large since angular momentum must be conserved. Does angular velocity change the mass of an object like linear velocity does or have any relativistic effects?

Whenever space is distorted, light has to follow the shape of space. In a sense, space is the medium that electromagnetic radiation propagates. Is it possible that gravity does not need space in order to propagate, so that when space is distorted, gravity does not follow it but continues on a "straight" path?

 

[Eeezee]

Originally posted by: firewolfsm
Another idea/question I had recently, this time about the gravitons that we haven't actually discovered yet.

I think that because every other force we know can only propagate through wave-particles, we assume the same for gravity (we also assume it's quantized but that's a different topic). If gravitons travel at the speed of light or less, then one would expect them to experience the same gravitational effects. That's the odd part I guess, why should they feel gravity if they're the source of the effect...I'm not really sure at this point but an object has a gravitational field and gravitons still have to pass through it.

Gluons are the force carriers of the strong force, yet they can also interact with each other (in fact, modern physical models attribute gluon-gluon interactions giving the proton/neutron the properties that we see, as opposed to the up/down quarks which play a lesser role). Thus, why shouldn't a graviton be able to interact with other gravitons?

The better question you should ask yourself is why can a force carrier have mass? The gluon and the photon are massless. Suddenly along come the W, the Z, and the Higgs (graviton)! Why should force carrying particles be susceptible to other force fields? The only easy answer is "Why not?" Courses in Quantum Field Theory are really required to better understand this subject.

Also, have you asked yourself how a massless particle can get trapped in gravitational field? Physics is fun like that. Ultimately, Newtonian gravity isn't good enough to answer that question (thanks GR)

 

[silverpig]

You can calculate the orbit of a photon around a black hole, or the deflection of a photon around a star with Newtonian physics and you do get a deflection. It's not like the answer is 0 because photons have 0 rest mass... The answer is wrong (by a factor of 2) but you still can calculate it.