[geordief]

That is incorrect. Light is always moving when going into a black hole. It's merely slowing down. A particle like a photon can always be moving towards the event horizon and still never get there. Its sort of like Zeno's paradox. First its moving at c, then later at c/2 then c/4 then c/5 ....... At no time in that sequence is the photon at res

Does it follow from that that light slows down  (from an observer's perspective) whenever it goes into any gravitational well (eg the Sun) ?

[guest46746]

When traveling at the speed of light, time slows down and may even stop, the environment is at essentially at a 0 rest state. Now imagine an environment that is comprised of solely radiant energy. EM/Light and Gravity.
The environment is completely contained. Everything in regards to its characteristic attributes has been made homogenous.Gravitaional attraction is unaltered across the expanse of the containment, this is due to a monopole singularity, it has no wave structure only presence. Light trapped by this monopole's singularity gravitational force also is without a wave dynamic, because of the monolithic nature of the monopoles gravity (no waves). So, with no Light waves, there becomes no differentials between objects moving at different velocities passed each other, this eliminates time. With time eliminatated there is no measurement of distance, with no measurement of distance there can be no space.

This describes both a quantum environment and a BH! …… doing this buck naked! well almost! lol

[yor_on]

Another interesting question would be if light ever could have a geodesic towards a event horizon. After all, the closer you get to a possible 'center' the closer to that would the geodesic path be, if now something could be 'reflected'? And in the case where a center would be every/thing/where inside a event horizon the question wouldn't even exist, would it?

And I think Pete was thinking of a 'photon' from a far away observers perspective there.
=

Although maybe not? You can argue that 'photon' slows down by gravity, myself I think of it as following a geodesic path (using main stream physics) which hopefully keep it at 'c'. When one argue that is slows down, it should be relative a distance locally measured as well as ones local wrist watch,

[evan_au]

Light trapped by this monopole's singularity gravitational force also is without a wave dynamic, because of the monolithic nature of the monopoles gravity (no waves). So, with no Light waves...

This post seems to be suggesting that there can be no light waves within a black hole (ie no light and no photons)?

One tool used by physicists is the "light cone", a volume of space within which light could propagate in a given time.

And physicists are happy to draw light cones at any position outside a black hole's event horizon - and even extrapolate across the event horizon to predict what might happen inside the event horizon.

The results within the event horizon are weird to our eyes - for example, time and space axes appear to be interchanged.
- However, there is nothing that prevents light from propagating - providing it propagates towards the singularity at the center of the black hole
See: https://en.wikipedia.org/wiki/Light_cone#In_general_relativity

[PmbPhy]

Light trapped by this monopole's singularity gravitational force also is without a wave dynamic, because of the monolithic nature of the monopoles gravity (no waves). So, with no Light waves...

This post seems to be suggesting that there can be no light waves within a black hole (ie no light and no photons)?

One tool used by physicists is the "light cone", a volume of space within which light could propagate in a given time.

And physicists are happy to draw light cones at any position outside a black hole's event horizon - and even extrapolate across the event horizon to predict what might happen inside the event horizon.

The results within the event horizon are weird to our eyes - for example, time and space axes appear to be interchanged.
- However, there is nothing that prevents light from propagating - providing it propagates towards the singularity at the center of the black hole
See: https://en.wikipedia.org/wiki/Light_cone#In_general_relativity

Bee - eeee - ay - yutiful!

[PmbPhy]

That is incorrect. Light is always moving when going into a black hole. It's merely slowing down. A particle like a photon can always be moving towards the event horizon and still never get there. Its sort of like Zeno's paradox. First its moving at c, then later at c/2 then c/4 then c/5 ....... At no time in that sequence is the photon at res

Does it follow from that that light slows down  (from an observer's perspective) whenever it goes into any gravitational well (eg the Sun) ?

The coordinate speed of light does slow down in a gravitational field. Einstein showed this in is 1911 paper.

The proof is on my website here: http://www.newenglandphysics.org/physics_world/gr/c_in_gfield.htm

Note the references at bottom of page. This slowing down of light was demonstrated by Irwin Shapiro in the 60's.

[Bill S]

That is incorrect. Light is always moving when going into a black hole. It's merely slowing down. A particle like a photon can always be moving towards the event horizon and still never get there. Its sort of like Zeno's paradox. First its moving at c, then later at c/2 then c/4 then c/5 ....... At no time in that sequence is the photon at rest.

And I think Pete was thinking of a 'photon' from a far away observers perspective there.

Although maybe not? You can argue that 'photon' slows down by gravity, myself I think of it as following a geodesic path (using main stream physics) which hopefully keep it at 'c'. When one argue that is slows down, it should be relative a distance locally measured as well as ones local wrist watch,

I’ve got another example of Zeno’s paradox.  The nearer I come to grasping these concepts, the more slowly I reach any sort of conclusion. 😊

Let’s see if I’ve grasped this.

An observer, falling into a BH, crosses the event horizon without incident and is then inside the BH.
A distant observer sees the infalling body as slowing to a standstill at the event horizon.

A photon, falling into a BH, crosses the event horizon without incident and is then inside the BH.
A distant observer sees the infalling photon as slowing, and never reaching the event horizon.

So, an assertion such as “A particle like a photon can always be moving towards the event horizon and still never get there.” Applies only to the RF of the distant observer.  In its own RF (if it could be said to have one), or in the RF of the BH, the photon would cross the event horizon without hesitation.

Because relativity tells us that every RF has as much right as any other to be considered as “real”, the photon crosses the event horizon, and does not cross the event horizon; and both of these scenarios exist, physically, in our Universe.

Am I getting anywhere, or does Zeno still rule?

[Bill S]

Pete, my post crossed over with yours.  I followed your link and, as usual when I look at your maths, I was full of admiration, but lacking in understanding.  I’m not sure if it throws any light on my last question, or not. 

Dealing with a mathematical ignoramus must be frustrating, but I know from the past that you have patience.

[Butch]

All of that is wrong. Where did you get that idea from?

I will see if I can find a reputable link, in the meantime can you explain why you believe it to be wrong?

This should suffice!
https://www.astro.umd.edu/~miller/poster1.html [nofollow]

[Butch]

That is incorrect. Light is always moving when going into a black hole. It's merely slowing down. A particle like a photon can always be moving towards the event horizon and still never get there. Its sort of like Zeno's paradox. First its moving at c, then later at c/2 then c/4 then c/5 ....... At no time in that sequence is the photon at rest.

It does not slow down, it only appears so to an outside observer, black holes are really not that mysterious, they are simply bodies with an escape velocity greater than c.

[evan_au]

So, an assertion such as “A particle like a photon can always be moving towards the event horizon and still never get there.” Applies only to the RF of the distant observer.  In its own RF (if it could be said to have one), or in the RF of the BH, the photon would cross the event horizon without hesitation.

We start splitting hairs when we start talking about the behavior of a single photon as seen by different observers...

A single photon may cross the event horizon and enter the black hole (in which case the distant observer doesn't see it at all)
- Or a single photon may slingshot around the black hole, reversing direction so the distant observer can see it - but it does not enter the black hole.

I suggest that these thought experiments about things entering black holes are best described in the context of an observer falling into a black hole, who carries a beacon which is emitting photons in all directions. That way, you can talk about the viewpoint of the infalling observer, and the viewpoint of the distant observer, without having to divide a single photon into 2 parts traveling in opposite directions...

[guest46746]

Light trapped by this monopole's singularity gravitational force also is without a wave dynamic, because of the monolithic nature of the monopoles gravity (no waves). So, with no Light waves...This post seems to be suggesting that there can be no light waves within a black hole (ie no light and no photons)?One tool used by physicists is the "light cone", a volume of space within which light could propagate in a given time.And physicists are happy to draw light cones at any position outside a black hole's event horizon - and even extrapolate across the event horizon to predict what might happen inside the event horizon.The results within the event horizon are weird to our eyes - for example, time and space axes appear to be interchanged.- However, there is nothing that prevents light from propagating - providing it propagates towards the singularity at the center of the black hole

If you except that Light has a dual nature of wave and particle. You must question whether Light must be in a wave form within the gravitational force of a BH.  A vacuum is void of matter. 


"The photon has zero rest mass and always moves at the speed of light within a vacuum".


Is the area within a BH's gravitational force a vacuum? No. I would say that it is a densely compressed region of photonic energy sharing the same quantum time/space local. Photons becoming particles, forced by the BH's gravity to share the same quantum space/time location. At a point, this compression becomes finite to the point of creating actual Light mass, Light particle duality. Once Light achieves particle mass it no longer is capable of traveling at the speed of light, as it inversely increases it density it regards to velocity. Particle density blocks light. The active region surrounding a BH is immerse and continually growing. Light becomes visible when it hits mass. The area of visible Light around a BH is again immerse. The area of a BH is relatively microscopic compared to the outer regions of it's BH gravity. If light inside the BH's gravitational force was indeed traveling at the speed of light, the immerse area we see surrounding it would not be reflecting the incoming Light that we observe on the outside. If Light in the gravitational field of the BH was indeed moving at the speed of light, we would actually be seeing empty space  all the way to the BH's Event Horizon. But we don't !  lol.

[evan_au]

we would actually be seeing empty space  all the way to the BH's Event Horizon. But we don't !

In fact, at the time of writing, we (the public) have not seen a black hole at all, down to the event horizon or not.

However, over the past year or so, the Event Horizon Radiotelescope has been trying to image the black hole at the center of our galaxy. They have been crunching the numbers for months now, but I haven't heard an announcement, or seen an actual image.
See: https://en.wikipedia.org/wiki/Event_Horizon_Telescope
Watch this space!

Is the area within a BH's gravitational force a vacuum?

The gravitational field of a black hole extends "to infinity". Most of this volume is a vacuum.

A black hole with a stellar companion will draw in gas to form an accretion disk. But the accretion disk is a fairly flat pancake, leaving most of the surrounding volume as a pretty good vacuum.

If you mean the singularity is not a vacuum, I would agree with you. But this is a miniscule volume at the center of the black hole.

At a point (within a black hole), this compression becomes finite to the point of creating ... Light particle duality

You don't need a black hole to create light particle/wave duality. You can demonstrate this at atmospheric pressure - or even in a vacuum chamber.

The area of visible Light around a BH is again immerse.

Are you talking about the luminous region of a black hole's accretion disk?
Nothing else about a stellar-mass black hole is visible (unless you can measure Hawking radiation with an effective black-body temperature of nanoKelvins).
See: https://en.wikipedia.org/wiki/Accretion_disk

[Bill S]

We start splitting hairs when we start talking about the behavior of a single photon as seen by different observers...

It’s easy to slip into talking about the “behaviour” if a photon, but, as I understand it, the only behaviour a photon exhibits is travelling.  Observation involves interaction, and interaction causes a photon to cease to be a photon.  The same must apply to a collection of photons. (?)

[guest46746]

QuoteIs the area within a BH's gravitational force a vacuum? The gravitational field of a black hole extends "to infinity". Most of this volume is a vacuum.

The BH has a finite beginning even if it is only a point. Hawking's believed it eventually evaporates, The BH gravitational field extending "to infinity" ? That would require it to extend beyond our Universe. 

[guest46746]

QuoteAt a point (within a black hole), this compression becomes finite to the point of creating ... Light particle dualityYou don't need a black hole to create light particle/wave duality. You can demonstrate this at atmospheric pressure - or even in a vacuum chamber.

Certainly, which make the likelihood of it occurring within the compression of the BH gravitational field even more prolific.

[guest46746]

QuoteThe area of visible Light around a BH is again immerse.Are you talking about the luminous region of a black hole's accretion disk?

The illuminous region around the BH's gravitational field represents it's external boundary, this is a reflection of the incoming light striking a mass. My point was that light within the gravitational field of the BH has particle mass. This reflection is similar to what occurs on a star, The cooler substrata below the star's surface creates a barrier that the hotter corona reflect off of. During a coronal we see the cooler substrata mass. The BH's photon particle mass in it's gravitational field is too dense to travel at the speed of light.  lol

[Bill S]

The BH has a finite beginning even if it is only a point. Hawking's believed it eventually evaporates, The BH gravitational field extending "to infinity" ? That would require it to extend beyond our Universe.

Welcome to my soapbox! 

Actually, I don't need it any more, as far as this particular usage of "infinity" goes.  I've come to terms with the fact that it simply means a great distance, for which we can find no end, either in practice or in principle.

As far as extending beyond our Universe is concerned; that must depend on whether or not you think the Universe infinite.

Slightly different soapbox - still occupied! 

[guest45734]

Dealing with a mathematical ignoramus must be frustrating, but I know from the past that you have patience.

Hi Bill My misses emailed me a paper on BH's this morning that is taking some getting my head around, so I set about googling for some explanations and stumbled across this on the NASA site, it may help a mathematical ignoramus as long as they are not a total ignoramus https://www.nasa.gov/pdf/377674main_Black_Hole_Math.pdf

The paper I was trying to get my head around is more up @PmbPhy  street on BH's. Its going to take me some time to understand what they are talking about https://arxiv.org/abs/1810.0847 Black Hole Entropy and Soft Hair.

[PmbPhy]

Are you taking the piss, in what universe does matter get stuck outside the event horizon of a black hole. Do you have a citation?

I heard that phrase "Are you taking a piss?" in the movie Kingsman: The Secret Service. What does it mean? I live in New England. Is that phrase a British thing?

Citation? Sure On the Influence of Gravitation on the Propagation of Light by Albert Einstein, Annalen der Physik[/b], 35, 1911.

Do you have a reason to claim otherwise?