[guest45734]

However, real gravitons propagate away to infinity, as oscillations on the gravitational field. This is what LIGO detected. (And real photons propagate away to infinity, as oscillations on the electromagnetic field. This is what telescopes detect.)

LIGO detected gravitational waves as predicted by EFE not gravitons. Gravitons are theorized to exist and have such low energy levels that we can not detect them with todays technology.

Bosons can not escape a BH, a graviton is a 2 spin boson how can it get out of a BH. A gamma ray cannot escape the event horizon of a BH and it has significantly more energy.

But the trend is certainly valid - gravitational waves of higher frequency (ie gravitons of shorter wavelength) will carry more momentum. The same relationship is true of photons.

Gravitational waves definitely exist gravitons might not exist, and might not have enough energy to escape a BH.

That there is an asymmetry between matter and antimatter is a mystery.

Why would you think an asymmetry should exist? An electron and positron when colliding produce 2 gamma rays(bosons) with 511eV of energy, the energy is not destroyed, it just changes form, the BB theory started with lots of radiation(bosons). For a zero energy universe you need +ve energy and -ve energy, not matter and antimatter. One way of achieving this is to regard dark energy (expansion of space) and gravity (contraction of space) as manifestations of one form energy and all other forms of energy as  opposite to this. Conversely to the above with this view the graviton(virtual particle) flows towards mass not away and is a virtual particle.

[Janus]

However, real gravitons propagate away to infinity, as oscillations on the gravitational field. This is what LIGO detected. (And real photons propagate away to infinity, as oscillations on the electromagnetic field. This is what telescopes detect.)

LIGO detected gravitational waves as predicted by EFE not gravitons. Gravitons are theorized to exist and have such low energy levels that we can not detect them with todays technology.

If gravitons exist (Gravity can be explained with a quantum theory), then gravitational waves would consist of gravitons.

Bosons can not escape a BH, a graviton is a 2 spin boson how can it get out of a BH. A gamma ray cannot escape the event horizon of a BH and it has significantly more energy.

Gravitons can't,  but since gravity would be mediated by virtual gravitons, this is no different from the fact that photons can't escape a BH, yet a BH can have a charge and an electromagnetic field mediated by virtual photons.

Gravitational waves definitely exist gravitons might not exist, and might not have enough energy to escape a BH.

Gravitational waves can't escape a BH either (By this I mean that gravitational waves cannot get out from inside the event horizon anymore than electromagnetic waves can.)

[jeffreyH]

The asymmetry problem explained at cern.
https://home.cern/topics/antimatter/matter-antimatter-asymmetry-problem

[Bill S]

I expect that black holes will deflect gravitons, just like they deflect photons. So maybe one day we may be able to do graviton spectroscopy by diffracting them with an array of micro-black holes?

Just checking!  The gravitational field is scalar.  If the gravitational field is composed of gravitons, the gravitons don’t have directionality.  If this is the case; how could they be deflected?

  However, real gravitons propagate away to infinity, as oscillations on the gravitational field. This is what LIGO detected. (And real photons propagate away to infinity, as oscillations on the electromagnetic field. This is what telescopes detect.)

By analogy with water waves, one might reason that individual gravitons within a gravitational wave would not propagate in the direction of the apparent motion of the wave.  Only energy would propagate in that way.  Again; how could the gravitons be deflected?

[guest45734]

If gravitons exist (Gravity can be explained with a quantum theory), then gravitational waves would consist of gravitons.

Gravitons can't,  but since gravity would be mediated by virtual gravitons, this is no different from the fact that photons can't escape a BH, yet a BH can have a charge and an electromagnetic field mediated by virtual photons.

Am I be correct in thinking that "virtual gravitons" and "virtual photons" are simply a convenient mathematical way of explaining how forces are transmitted and that they may not actually exist as virtual particles at a point in space??? 

The magnetic field and electric charge of a BH is normally attributed to the accretion disc, are you saying a magnetic field can escape from inside a BH ? .

Gravitational waves can't escape a BH either (By this I mean that gravitational waves cannot get out from inside the event horizon anymore than electromagnetic waves can.)

Yes I think I understand you. The distortion of space time increases towards a BH, two BH's orbiting each other modulate space time causing the gravitational waves.

The asymmetry problem explained at cern.
https://home.cern/topics/antimatter/matter-antimatter-asymmetry-problem

That link just points out there is a problem with the current model. ie it does not fit the observed universe.

Just checking!  The gravitational field is scalar.  If the gravitational field is composed of gravitons, the gravitons don’t have directionality.  If this is the case; how could they be deflected?

Would gravitational frame dragging be of any consequence to your question https://www.space.com/456-einstein-warped-view-space-confirmed.html

[evan_au]

The magnetic field and electric charge of a BH is normally attributed to the accretion disc, are you saying a magnetic field can escape from inside a BH ?

According to Special Relativity, Black Holes only have 3 properties that are detectable external to the black hole: Mass, Angular Momentum & electric charge.

These properties are detectable from black holes with no accretion disk.
See: https://en.wikipedia.org/wiki/No-hair_theorem
(Let's ignore information paradoxes and hypothetical magnetic monopoles for now - these are not covered by Special Relativity.)

Black holes have spin and electric charge, yet they are thought to have no magnetic field of their own - perhaps because the electric charge is concentrated at the singularity at the center?

However, if you have a moving electric charge, that movement creates a magnetic field (whether it be a moving electron or a moving black hole). But if you are stationary near a black hole, you would not detect a magnetic field.

On the other hand, accretion disks around a black hole consist of rapidly spinning conductive plasma disk which drags magnetic fields with it, and tangles them up, releasing huge amounts of energy as particle jets emanating from the poles (but still only a fraction of the energy of the matter falling into the black hole). An accretion disk  is something that you find outside the event horizon, so the particles and magnetic field field don't need to escape from within the black hole.
See: https://en.wikipedia.org/wiki/Accretion_disk#Magnetic_fields_and_jets

[Bill S]

Interesting link, Dead Cat, thanks. 

On an initial scan, I can't see that it says anything about the possible motion of a scalar field.

[guest45734]

By analogy with water waves, one might reason that individual gravitons within a gravitational wave would not propagate in the direction of the apparent motion of the wave.  Only energy would propagate in that way.  Again; how could the gravitons be deflected?

I may be wrong here but virtual gravitons would be absorbed by mass and not reflected, whereas the water wave energy is not absorbed and can be reflected by a sea cliff and cause confused waves. Also water is not a virtual particle it exists for a long time. A modulation in the density of virtual particles might be analogous to a water wave, compressing and releasing and contracting.

All of space is full of virtual particles as predicted by the HUP. There is no such thing a a perfect vacuum, and space time does not exist without the appearance of virtual particles. 

[Bill S]

I may be wrong here but virtual gravitons would be absorbed by mass and not reflected,

Were we talking about virtual gravitons (whatever they might be)?

whereas the water wave energy is not absorbed and can be reflected by a sea cliff and cause confused waves.

I don’t think you can compare the motion of water once a wave has broken against a cliff with the smooth passage of an unbroken wave.  The mechanics would be totally different.
 

Also water is not a virtual particle it exists for a long time.

I was responding to:

  However, real gravitons propagate away to infinity, as oscillations on the gravitational field…

In order to do that, they would have to exist for a very long time.  Infinitely long (?).

[guest45734]

I may be wrong here but virtual gravitons would be absorbed by mass and not reflected,

Were we talking about virtual gravitons (whatever they might be)?

whereas the water wave energy is not absorbed and can be reflected by a sea cliff and cause confused waves.

I don’t think you can compare

  However, real gravitons propagate away to infinity, as oscillations on the gravitational field…

In order to do that, they would have to exist for a very long time.  Infinitely long (?).

A contraction of space and the density of virtual particles, followed by an expansion of space and an increase of virtual particles could be viewed as   infinite wave rippling through space. The virtual graviton could also be viewed as dark energy perhaps

[Bill S]

infinite wave rippling through space.

 I always have reservations about using “infinite” to describe some finite thing, or process, for which we can see no end.  However, as long as we acknowledge that we are talking about our perception, rather than the actual nature of the object/process, I know what you mean.

The virtual graviton could also be viewed as dark energy perhaps

Graviton = so far undetected particle.
Virtual particle = not a particle at all.
Dark energy = something of which we have only indirect evidence.

You could have a very valid point, but I suspect that convincing maths and/or hard evidence would be needed to drag it out of the realms of speculation.

Keep speculating, though, I’m a great fan of speculation.

[guest45734]

infinite wave rippling through space.

The virtual graviton could also be viewed as dark energy perhaps

Graviton = so far undetected particle.
Virtual particle = not a particle at all.
Dark energy = something of which we have only indirect evidence.

You could have a very valid point, but I suspect that convincing maths and/or hard evidence would be needed to drag it out of the realms of speculation.

Keep speculating, though, I’m a great fan of speculation.

The graviton is speculation, and most likely does not exist. Virtual particles which are vacuum fluctuations do exist as proven by the casimir effect and suggested by the well established HUP.

Virtual photons mediating the magnetic field, or a gravitational field, are virtual particles otherwise generically known as quantum fluctuations.

Dark energy as a result of quantum fluctuations out of the vacuum of space is an active area of research. Yes there are mathematical problems, as there appears to be with relativity predicting random amounts of dark matter to explain the apparent additional forces required at the outer edges of spiral galaxies to hold them together.

[Bill S]

Virtual particles which are vacuum fluctuations do exist as proven by the casimir effect and suggested by the well established HUP.

I'm not questioning the vacuum fluctuations, but are they actually particles?

Dark energy as a result of quantum fluctuations out of the vacuum of space is an active area of research.

No quarrel there, either, but string theory is also an active area of research.  As far as I am aware, they would both benefit from some practical/physical support.

Please don't think I'm knocking speculation or thinking outside the box, just commenting on the fact that  a bit of back-up is a good thing.

[jeffreyH]

If you feel that the gravitational field does not have quanta then you have to explain an alternative cause of gravitational waves. You can't just say they don't exist.

[Bill S]

Are quanta and particles necessarily the same thing?  I'm struggling to think of a quantum that is not considered to be a particle.  Virtual particles are as near as I can get.

[PmbPhy]

Hey all

Quick question for you. I hear all the time, 'the elusive gravity particle' . But why do we even need one? Doesn't Einstein's General theory describe gravity as mass warping space/time.

No. It describes gravitational tidal forces as a curvature in spacetime. But that's not all there is to gravity. You can have a uniform gravitational field which has zero spacetime curvature. Another example is described in the American Journal of physics. I.e. See

Cosmic strings: Gravitation without local curvature by T.M. Helliwell, Am. J. Phys.,55(5), May (1987)

Abstract: http://dx.doi.org/10.1119/1.15145http://dx.doi.org/10.1119/1.15145

Cosmic strings are very long, thin structures which might stretch over vast reaches of the universe. If they exist, they would have been formed during phase transitions in the very early universe. The space‐time surrounding a straight cosmic string is flat but nontrivial: A two‐dimensional spatial section is a cone rather than a plane. This feature leads to unique gravitational effects. The flatness of the cone means that many of the gravitational effects can be understood with no mathematics beyond trigonometry. This includes the observational predictions of the double imaging of quasars and the truncation of the images of galaxies.

The article has an odd title since all curvature is, at a minimum, local.

[PmbPhy]

Are quanta and particles necessarily the same thing?  I'm struggling to think of a quantum that is not considered to be a particle.  Virtual particles are as near as I can get.

Quanta is the plural form of quantum. A quantum doesn't need to be a particle. See definition at:
https://en.oxforddictionaries.com/definition/quantum

It just means "discrete amount." For example: A harmonic oscillator has discreet energy levels in which it can be in. Those levels are said be quantized.

[Bill S]

Quanta is the plural form of quantum.

That's why I said, "are quanta"......and ....."a quantum".

I am always a little cautious about using dictionary definitions in scientific discussions.  I don't remember if it was you or Alan who cautioned against that.

Thanks for the clarification, though.

[Bill S]

..... A harmonic oscillator has discreet energy levels in which it can be in. Those levels are said be quantized.

I know very little about harmonic oscillators.  Can their "energy levels" interact/interfere with one another?

[evan_au]

I know very little about harmonic oscillators.  Can their "energy levels" interact/interfere with one another?

Probably the simplest, most familiar harmonic oscillator is the pendulum.
The pendulum will swing (oscillate) with a frequency which is related to the length of the string, and the strength of Earth's gravity.

If you tie several pendulums (penduli??) to a common string, they will interact with each other, transferring energy from one pendulum to the other via the string. Depending on the relative frequencies, you can get behaviors like:
- 1 Pendulum: Simple Harmonic motion
- 2 Pendulums: They transfer energy backwards and forwards between them, with first one swinging, then the other swinging
- 3 Pendulums: Here it gets really complicated, with chaotic motion that shows no consistent pattern over time. Even small changed in the conditions can produce big changes in the behavior (subject to the overriding conservation of energy)
- 4 or more: Generally unpredictable (subject to the overriding increase of entropy)

Of course, familiar macroscopic examples like this rarely transfer directly to the atomic world of electrons and atoms, where the energy levels are quantised; the energy of a clock pendulum does not appear to be quantised (possibly because we can't measure it accurately enough).