If photon is mass-less why can it be pulled into blackhole?

[QuarkHead]

You know, one could be forgiven for thinking you don't read even your own posts. I quote you

Einstein general relativity is a metric theory, what is the physical reality of metric, none knows.

When I disagreed to the extent that even I understood the metric, you responded with link that pointed that there is at least one non-metrical theory of gravitation. And this is not Einstein's, which you refer to above

Answer me this: If a valid non-metric theory of gravitation exists, why is there any need to "understand the physical reality of the metric"?

 

[The God]

You know, one could be forgiven for thinking you don't read even your own posts. I quote youWhen I disagreed to the extent that even I understood the metric, you responded with link that pointed that there is at least one non-metrical theory of gravitation. And this is not Einstein's, which you refer to above

Answer me this: If a valid non-metric theory of gravitation exists, why is there any need to "understand the physical reality of the metric"?

Good you read the link.
Rest all is an attempt to drag on your trivial metric attempt despite the fact that in very first response (#17) I clarified and pointed out the context.

 

[Write4U]

IMO, movement from one spacetime coordinate to the adjacent coordinate is a function of QM.
A photon cannot travel faster than c, because it needs to renew itself as a discreet particle. This function requires time and is what restricts even a massless particle from traveling at infinite speed.
At superluminal speed a particle is no longer a discrete energetic packet but becomes a set of "enfolded" virtual entities, a probabilistic potential.

 

[DaveC426913]

A photon cannot travel faster than c, because it needs to renew itself as a discreet particle.

W4U, I have reported this post with a request to remove it; it is an unsubstantiated opinion. It might be fine for other subfora, but it does not belong in a hard-science forum, where people should be able to expect science-based information about their questions.

 

[Write4U]

W4U, I have reported this post with a request to remove it; it is an unsubstantiated opinion. It might be fine for other subfora, but it does not belong in a hard-science forum, where people should be able to expect science-based information about their questions.

I fundamentally agree with your argument, but my posit was not based on pure speculation, but rather a probative statement, based on the following;

Quanta of EM waves are called photons, whose rest mass is zero,

and

the quantum theory of electromagnetism, EMR consists of photons, the elementary particles responsible for all electromagnetic interactions. Quantum effects provide additional sources of EMR, such as the transition of electrons to lower energy levels in an atom and black-body radiation. The energy of an individual photon is quantized and is greater for photons of higher frequency.

https://en.wikipedia.org/wiki/Electromagnetic_radiation

To me these examples demonstrate a relationship between QM and SOL. (EMR)
If this is completely outside the parameters of the discussion, I'll be happy to sit back and just follow the arguments from "learned fellows".

 

[Schmelzer]

If photon is mass-less why can it be pulled into blackhole?

I see there has not really been an answer yet.

In Einstein's GR, it is not the mass which attracts (and is attracted) via the gravitational field, but the energy-momentum tensor.

If the velocities are small, the main contribution to the energy-momentum tensor comes from energy, and the energy is roughly defined by the mass. Roughly, the energy is $E = m c^2 + \frac12 m v^2 + \ldots$. If the velocity is small, you can ignore the part which depends on the velocity and get the famous $E=mc^2$. (Which is today only a rough approximation - at Einstein time, a notion of "relativistic mass", which depends on the velocity, was defined, and with this variable mass the formula was exact. Today that "relativistic mass" is no longer used, the only mass used today was, at that time, called "rest mass". And for the "rest mass", the formula $E=mc^2$ is correct only if the body is in rest.)

The exact relativistic formula would be $E^2 - p^2c^2 = m^2c^4$. So, neither energy nor momentum is zero if the mass is zero. The momentum of a photon is defined by $p=2\pi\hbar\nu$ via the frequency. With nonzero energy and momentum it is attracted by gravity and attracts other things too.

 

[Confused2]

If you want to know exactly what the metric is in GR (it's actually a field), I can give 2 arguments, one of which requires some familiarity with the differential calculus. But both involve mathematics, which you appear to despise as applied to physics.

I don't despise maths and have 'some' differential calculus and I'm interested - if you choose to reply please could you keep it as simple as possible even at the expense of strict accuracy.

 

[hansda]

If you want to know exactly what the metric is in GR (it's actually a field), I can give 2 arguments, one of which requires some familiarity with the differential calculus. But both involve mathematics, ...

Which part of GR, do you think is a field? Is it spacetime? or The math of spacetime? Do you think this field (of GR) is similar to magnetic field or electrical field?

 

[hansda]

I see there has not really been an answer yet.

In Einstein's GR, it is not the mass which attracts (and is attracted) via the gravitational field, but the energy-momentum tensor.

My understanding of Einstein's GR, is that spacetime curves due to mass and movement of mass is due to curvature of spacetime. The concept of attraction is perhaps not used in GR model but it is used in Newtonian model.

With nonzero energy and momentum it is attracted by gravity and attracts other things too.

Isn't it due to curvature of spacetime?

'Attraction by gravity' - Is it GR concept or Newtonian concept?

 

[hansda]

If photon is mass-less why can it be pulled into blackhole?

Particle photon's trajectory is alongwith the spacetime. Curvature of spacetime around a blackhole is very high. The spacetime can not escape the blackhole. So, particle photon also can not escape the blackhole.

 

[Write4U]

Regarding photons: inside the event horizon, we know that that photons will make their way towards the centre of the black hole. But individual photons aren't divisible, as far as we can tell. You can't pull a photon into two separate pieces. We don't know what happens at the centre of a black hole, so we can't say what, exactly, happens to photons there.

As I understand Hawking Radiation, the theory posits that this happens near the event horizon of a BH and it is a quantum function, i.e. a change of energy state so large that some electrons not only change orbit, but completely break away from the internal strong gravity of an atom itself and escape into space.

In 1975 Hawking published a shocking result: if one takes quantum theory into account, it seems that black holes are not quite black! Instead, they should glow slightly with "Hawking radiation", consisting of photons, neutrinos, and to a lesser extent all sorts of massive particles. This has never been observed, since the only black holes we have evidence for are those with lots of hot gas falling into them, whose radiation would completely swamp this tiny effect. Indeed, if the mass of a black hole is M solar masses, Hawking predicted it should glow like a blackbody of temperature.
6 × 10-8/M kelvins,

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/hawking.html

Is this not already a sign that atoms are being pulled apart and the lightest sub-particles (electrons with zero mass) escape while most of the heavier sub-particles continue down into the hole?

 

[DaveC426913]

a change of energy state so large that some electrons not only change orbit, but completely break away from the internal strong gravity of an atom itself and escape into space.

No.

Hawking radiation occurs with virtual particles.

The quantum vacuum seethes with energy, and frequently a bit of neutral vacuum can spontaneously split into a particle/antiparticle pair (think of positive/negative charges or positive/negative mass). The net effect of thee two particles is still zero, so nothing has been created - net charge is zero and net mass is zero.

Not that it matters, because they immediately annihilate each other, going back to non-existence -just another flavor of zero charge/mass.

But if this happens so close to the BH EH that one of them gets trapped and the other does not, the lone virtual particle, having no counterpart, becomes real (it now has a net effect, since its canceling counterpart can no longer cancel it), and escapes from the BH, resulting in a net energy loss in the form of a real particle being emitted from the BH.

 

[Write4U]

No.

Hwking radiation occurs when virtual particles (which occur as a pair of virtual particle/antiparticle, that pop into existence spontaneously and then immediately annihilate each other) are created so close to the BH EH that one of them gets trapped and the other does not. The lone virtual particle, having no counterpart, becomes real, and escapes from the BH, resulting in a net energy loss.

Interesting.
Would that indicate that the Higgs field near a BH becomes so condensed that it spontaneously creates virtual Higgs (and other) bosons, somewhat similar like we did at Cern?

 

[river]

I see there has not really been an answer yet.

In Einstein's GR, it is not the mass which attracts (and is attracted) via the gravitational field, but the energy-momentum tensor.

If the velocities are small, the main contribution to the energy-momentum tensor comes from energy, and the energy is roughly defined by the mass. Roughly, the energy is $E = m c^2 + \frac12 m v^2 + \ldots$. If the velocity is small, you can ignore the part which depends on the velocity and get the famous $E=mc^2$. (Which is today only a rough approximation - at Einstein time, a notion of "relativistic mass", which depends on the velocity, was defined, and with this variable mass the formula was exact. Today that "relativistic mass" is no longer used, the only mass used today was, at that time, called "rest mass". And for the "rest mass", the formula $E=mc^2$ is correct only if the body is in rest.)

The exact relativistic formula would be $E^2 - p^2c^2 = m^2c^4$. So, neither energy nor momentum is zero if the mass is zero. The momentum of a photon is defined by $p=2\pi\hbar\nu$ via the frequency. With nonzero energy and momentum it is attracted by gravity and attracts other things too.

This is nonsense .

Retracted .

In simple terms Schmelzer.

 

[James R]

Write4U:

Dave is right.

This thread is in our Science sections of the forum. It is not appropriate to post unsupported speculation that is non-scientific. By which I mean this kind of thing:

A photon cannot travel faster than c, because it needs to renew itself as a discreet particle. This function requires time and is what restricts even a massless particle from traveling at infinite speed.

This is a vague idea you have, which apparently has no basis in established science. A better forum would be our "Alternative Theories" section, if you have anything to flesh out your ideas. Otherwise, this is little better than a just-so story or guesswork.

At superluminal speed a particle is no longer a discrete energetic packet but becomes a set of "enfolded" virtual entities, a probabilistic potential.

Enfolded virtual entities are not part of physics, to my knowledge. Again, this idea seems to originate with you. It would be fine in the Science sections if you had an actual scientific argument to make about it, but apparently you do not.

 

[James R]

To be clear though , BH , is nonsense , to me .

How do you account for the orbits of stars around Saggitarius A*? What kind of object do you think they are orbiting, if not a black hole?

 

[river]

How do you account for the orbits of stars around Saggitarius A*? What kind of object do you think they are orbiting, if not a black hole?

Hmm... I guess it is a matter of perspective .

Are stars being attracted to the core , drawn in towards the galactic core or are stars being thrown out by the galactic core ?

 

[Write4U]

Write4U:

Dave is right.

This thread is in our Science sections of the forum. It is not appropriate to post unsupported speculation that is non-scientific. By which I mean this kind of thing:

This is a vague idea you have, which apparently has no basis in established science. A better forum would be our "Alternative Theories" section, if you have anything to flesh out your ideas. Otherwise, this is little better than a just-so story or guesswork.

I admit I cannot defend QM on scientific grounds.

Enfolded virtual entities are not part of physics, to my knowledge. Again, this idea seems to originate with you. It would be fine in the Science sections if you had an actual scientific argument to make about it, but apparently you do not.

It is my take on Bohmian Mechanics but again I cannot defend it scientifically.

I hope that I'll be allowed to pose an occasional question, if only to get a reference or link from reliable sources so I don't have to search the net for hours trying to find something which doesn't exist....

 

[Schmelzer]

My understanding of Einstein's GR, is that spacetime curves due to mass and movement of mass is due to curvature of spacetime.

Replace "mass" with "matter". Massless matter fields (like the EM field) also curve spacetime, and their movement is also influenced by curvature.

The concept of attraction is perhaps not used in GR model but it is used in Newtonian model.

Yes, the spacetime interpretation does not use it. The notion of force requires some standard of motion without force, which was the inertial motion. But inertial motion is straight line motion relative to a flat background which does not exist in GR.

In simple terms Schmelzer.

In GR, it is not mass but energy, momentum and pressure (which define, together, the energy-momentum tensor) which create some nontrivial gravitational fields.

For the difference, think about some piece of matter together with antimatter. Two equal masses. They would create a large gravitational field in Newtonian theory. Then they meet each other, and all the mass is transformed into something without mass, like radiation. So, once the mass disappeared, did the gravitational field disappear too? In GR, not, the energy remains the same.

 

[Write4U]

Did find this little bit though, which may or may not be relevant.

LHC experiment is first direct evidence of photon-on-photon scattering

https://www.sciencenews.org/article/lhc-atlas-photons-interact-physics