Gravitron Discovery: Could Mass-Energy Conversion Create Gravitrons?

[dbmorpher]

I was recently looking into how the Higgs Boson was somewhat discovered

From the article I had read it had said that a Z boson was smashed and lost it's mass creating a disturbance of mass in the area forcing the creation of the Higgs

Therefore if a Higgs Boson was created by the thurning of mass to energy why not a graviton?
It seems as a disturbance in the Higgs Field would also affect the Gravitational Field, and if so would gravitons be created too?

 

[Drakkith]

Gravitons may be created, but only if they actually exist. They have not been observed so far.

 

[chill_factor]

Gravitons cannot be detected even in principle. There is absolutely no way to shield any detector from neutrinos to distinguish a graviton signal from a neutrino one.

 

[Chronos]

Until we have some clue about graviton mass, this is an exercise in futility, IMO.

 

[snorkack]

Graviton has no mass. As can be verified by direct observation of emission of low frequency gravity waves. It is improbable that the energy loss could have been so exactly the predicted value unless gravitons were exactly what they are guessed to be, and traveling at light speed.

If any source of significant numbers of high frequency gravitons existed, they would have distinctive properties. Spin 2 - something which no other fundamental particle has, though hadron excited states might - and selection rules.

Could a high energy gravitational wave absorption event be distinguished from all other events - not just the high probability events but all low probability/forbidden line interactions?

 

[tom.stoer]

You are invited to calculate e.g. the electron-photon marix elements in order to compare them with electron-graviton matrix elements just to compare the strength of the interaction; it's impossible to detect single gravitons

 

[mfb]

From the article I had read it had said that a Z boson was smashed and lost it's mass creating a disturbance of mass in the area forcing the creation of the Higgs

??
That looks wrong.

 

[Nabeshin]

You are invited to calculate e.g. the electron-photon marix elements in order to compare them with electron-graviton matrix elements just to compare the strength of the interaction; it's impossible to detect single gravitons

Indeed, the impossibility might extend beyond just our crude detection apparatus. I recall reading a paper which did a rough calculation showing that any attempt to measure individual gravitational waves led to a measurement apparatus bordering on collapsing into a black hole!

Nevertheless, just to clarify, even though we don't have a quantum theory of gravity we DO know some things about the graviton:
1) Massless
2) Spin 2
3) 2 Transverse polarizations.

These all of course come from just classical GR, which is why we expect them to hold quite generally for any realization of the graviton.

 

[tom.stoer]

Nevertheless, just to clarify, even though we don't have a quantum theory of gravity we DO know some things about the graviton:
1) Massless
2) Spin 2
3) 2 Transverse polarizations.

These all of course come from just classical GR, ...

Yes.

... which is why we expect them to hold quite generally for any realization of the graviton.

No.

There are theories of quantum gravity where gravitons are not the building blocks. The most prominent one is LQG where gravitons may emerge in a certain regime as "effectice d.o.f". I agree that SUGRA and strings have gravitons as fundamental entities, but their reasoning based on classical, linearized GR translated into a perturbative, background-dependent quantum theory is their biggest obstacle towards a satisfactory theory of quantum gravity.

 

[negru]

There are theories of quantum gravity where gravitons are not the building blocks. The most prominent one is LQG where gravitons may emerge in a certain regime as "effectice d.o.f". I agree that SUGRA and strings have gravitons as fundamental entities, but their reasoning based on classical, linearized GR translated into a perturbative, background-dependent quantum theory is their biggest obstacle towards a satisfactory theory of quantum gravity.

It's irrelevant whether the graviton is fundamental or an effective d.o.f. It still has to be there, just like hadrons are effective d.o.f in QCD, but they are very much there, with the expected properties. Technically gravitons are effective d.o.f. in string theory too.

 

[tom.stoer]

The problem is not the fact that the gravitons should have these properties but that they are universal, fundamental entities and that all this can be derived from classical GR:

These all of course come from just classical GR, which is why we expect them to hold quite generally for any realization of the graviton.

You can't derive universal properties for gravitons from classical GR only. You can neither prove the existence nor derive the properties of water molecules by quantizing the Navier-Stokes equations.

 

[dbmorpher]

But photons are existent and have no mass
Could a gravitron be what gluons are made of
Could the Strong Gravitational force not be separated and just hiding in one another?
*Just questions*

 

[Drakkith]

But photons are existent and have no mass

Yep.

Could a gravitron be what gluons are made of

Gluons are fundamental particles and are not made of any other particles.

Could the Strong Gravitational force not be separated and just hiding in one another?
*Just questions*

There is no such thing as a "Strong Gravitational Force". The strong force, or color force, is what holds hadrons together, and it's "bleed-through" holds nucleons together in atomic nuclei.

 

[dbmorpher]

ok i get it now

 

[Nabeshin]

There are theories of quantum gravity where gravitons are not the building blocks. The most prominent one is LQG where gravitons may emerge in a certain regime as "effectice d.o.f". I agree that SUGRA and strings have gravitons as fundamental entities, but their reasoning based on classical, linearized GR translated into a perturbative, background-dependent quantum theory is their biggest obstacle towards a satisfactory theory of quantum gravity.

Admittedly, my knowledge of this comes more from the stringy point of view so I may have made too broad of a statement.

I want to get on the same page here... So in a theory like LQG or what have you, gravitons may not be fundamental entities but do they nevertheless possesses the three properties I mentioned? If not, do you have references for this?

 

[king vitamin]

There are theories of quantum gravity where gravitons are not the building blocks. The most prominent one is LQG where gravitons may emerge in a certain regime as "effectice d.o.f". I agree that SUGRA and strings have gravitons as fundamental entities, but their reasoning based on classical, linearized GR translated into a perturbative, background-dependent quantum theory is their biggest obstacle towards a satisfactory theory of quantum gravity.

Being ignorant of LQG, what do you mean by effective degrees of freedom (if there is a terse answer)? I can understand the argument that gravitons are emergent at low energy (if that's what you're implying), but under the same argument photons are not building blocks of the standard model, and I would not use this as evidence that photons don't exist.

 

[snorkack]

Can it be proven from pure Maxwell theory that a fully circularly polarized electromagnetic wave with energy E carries angular momentum L=E/ω?

And does it follow from general relativity that a fully circularly polarized gravitational wave with energy E carries angular momentum L=2E/ω?

 

[tom.stoer]

It's difficult b/c polarized plane waves are not localized and therefore not normalizable; the integrals will always diverge. But what you can do is either to construct wave packets or to look at the local densities w/o integration.

For the electromagnetic field you have to construct the generators of the Poinare algebra which are partially related to integrals of the energy-momentum tensor. These generators correspond to expressions

P^μ = (E,Pⁱ), Lⁱ, Kⁱ

for 4-momentum, angular momentum and boost generators.

From the local expression for the density in the integral of Lⁱ you should be able to derive that circular polarization corresponds to angular momentum.

For gravity it's much more complicated b/c full GR does not have global Poincare invariance and therefore the above construction becomes meaningless. But what one could do is to derive similar expressions for linearized gravity, i.e. gravbitational waves propagating on a fixed Minkowski background. Then - except for the fact that the expressions are more complicated - the above mentioned construction should become possible again.

 

[negru]

Here's a dumb question: is there any evidence for GR beyond the linear terms?

 

[mfb]

I think the linear terms are Newtonian gravity. So everything beyond that (perihelion shift, frame dragging, non-Newtonian deflection of light, Shapiro delay, ...) is evidence for GR.
The observation of accretion disks and binary pulsars allows to probe higher orders, although in an indirect way.

 

[tom.stoer]

No, the linear Terms are not Newtonian gravity but small, uncoupled gravitational waves on a static background. Besides the above mentioned indications gravitational waves (w/o linear apprioximation!) have been confirmed indirectly by the observed slowing down of pulsar rotation due to emission of gravitational waves.

 

[dbmorpher]

Man physicists have such heated debates

 

[negru]

On the other hand, starting from just gravitons, one is able to derive GR, no? So one can assume higher order terms can also be described by gravitons.

 

[tom.stoer]

On the other hand, starting from just gravitons, one is able to derive GR, no?

What do you mean by "starting from just gravitons"?

 

[negru]

Start with a massless spin 2 field, which couples in some consistent way to the stress energy tensor, and couples to itself. I thought it is accepted in the literature that this leads to full GR?

Some alternative assumptions also work http://arxiv.org/abs/0811.3207

 

[mitchell porter]

Could a graviton be what gluons are made of

It's more the other way around. In a lot of cases the formula for a graviton is the square of the formula for a gluon (see "KLT relations"). In string theory, a graviton is a closed loop and a gluon is (sometimes) a curve with endpoints, so the closed loop is like two curves attached at their ends.

 

[tom.stoer]

Start with a massless spin 2 field, which couples in some consistent way to the stress energy tensor, and couples to itself. I thought it is accepted in the literature that this leads to full GR?

It seems that I remember vaguely ...

Some alternative assumptions also work http://arxiv.org/abs/0811.3207

But this is purely perturbative and (at least currently) restricted to tree level; they say:

The BCFW recursion relation is a remarkable formula, demonstrating that the entire structure of Yang-Mills and gravity amplitudes at tree-level can be derived recursively from 3-point amplitudes, which are fully specified by their Lorentz structure.

...

We also expect that analogous structural constraints (such as anomalies) appear at one-loop