Neutrinos faster than the speed of light?

If a photon is emitted directly radially away from just outside the EH of a BH, it will be seen to hover for all eternity, never quite escaping, and never quite succumbing to the BH's EH in any FoR.
Other photons emitted at any other angle will be seen to secumb to the BH, in a local FoR only.

Is this what you are referring to pmb?

 

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You have the right idea but the way you described it is wrong. If a photon is emitted radially away from just outside the EH of a BH then they will escape. If they approach the BH EH from outside radially inward then, even though they never stop moving they'll keep slowing down never stopping but will never get to or pass the event horizon. Effecively they'll just hover about it just like you said.

I believe this is also explained in Exploring Black Holes - Second Version by Taylor, Wheeler and Bertschinger at http://exploringblackholes.com I don't want to bother digging through all those chapters to find what I know and have already proven to be the case though.

 

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OK, I seem to have a few problems with that description.....Let me explain.
As a layman, I am forced to look at this non-mathematically and in as simple a way as possible.
I have learned to picture a BH as a Waterfall of space...ie, a place where space/time flows inwards towards a singularity, faster then "c"
Do you see this as a valid analogy?
Or similar to a fast flowing river which reaches the speed of light at the EH.
There for a fish swimming radially directly away [against the flowing river] at "c" just at the horizon, would be seen to be stationary and hover from a local FoR, would it not? It would certainly not fall into the BH, but it would not quite get away either. space/time at the EH, falls/flows in at "c", the photon directed outwards is also moving at "c"

With the photons approaching the BH, they are seen as never to cross the EH from an outside FoR, but from a local FoR, they do cross the EH.
So whether they cross the EH, depends on ones FoR.
At least that is how I have been taught to view the scenario.

I have read two books on BH's Kip Thorne's "Black Holes and Time Warps" and also Sir Martin Ree's and Mitch Begalman's "Gravity's Fatal Attraction"

 

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I did find this........

Photons do not orbit in circles at the horizon, just skimming the surface. The place where photons orbit in circles is the photon sphere, at 1.5 Schwarzschild radii. Photons emitted at the horizon fall in; except that if a photon is emitted exactly vertically outward exactly at the horizon, then it will hover at the horizon, not moving at all.

from....

http://casa.colorado.edu/~ajsh/singularity.html#photon

 

Perhaps the confusion lies in what I originally said, re the photon emitted just above the EH, instead of at the EH.

 

Yes. Did you come up with this analogy all by yourself? If so then let me raise my glass to you and say Bravo! This appeared in the physic literature twice in the last 5 years

See;

[a]The river model of space[/b] by Braeck and Gron, European Physics Journal Plus. (2014) http://arxiv.org/abs/1204.0419

The river model of black holes by Hamilton, Lisle, Am.J.Phys.76, pp 519-532, (2008) http://arxiv.org/abs/gr-qc/0411060

Box 7 on page 7.22 of Exploring Black Holes – Second Ed. by Taylor, Wheeler and Bertschinger - http://www.eftaylor.com/exploringblackholes/InsideBH131201v2.pdf

If he’s at the event horizon then yes, he’d hover there. I was talking about the ones just outside the event horizon. This is where our confusion lies. I’m very glad you mentioned this. Thanks.

Precisely, M’man!

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I have Thorne’s text but not the other. Thorne’s text is great. How’s the one?

 

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Put your glass back down....I can't remember where I did first see that analogy, but no, its not mine originally.
As a layman, I find analogies quite useful and revealing, while of course realising they do have limitations.

Ree's and Begalman,s book is rather too mathematical for my liking, but OK, while Thorne's book seemed far more easy to comprehend from my point of view. I'm actually about to head into my third read. I seem to always pick up a little more info and understanding with successive reads.

 

Bingo!!!!


http://jila.colorado.edu/~ajsh/insidebh/index.html

 

Yes Pete. I'm pleased that you have nothing further to say.

 

The speed of light does not change, even in a gravity well. As long as the photon is travelling through vacuum(IE not in a medium)it is travelling at lightspeed. What gravity and electromagnetic fields can do is shift the spectrum of that light, reduce or increase it's energy or change it's vector, they cannot affect it's velocity. If it is a photon, it is travelling at light speed. "Slow" light has never been seen. Time and space will warp to the extent that is necessary for lightspeed to be the same in all FoR and between all frames. It is called a CONSTANT because it has always been measured to be so, constantly the same no matter what. Anyone who claims otherwise has a huge task of showing that to be true. It's never been done yet, every photon ever observed so far is travelling at lightspeed, from all directions and from all sources, accelerating, coasting or at rest. There is no Doppler in lightspeed, only in it's spectrum.

paddoboy

No, for nothing with mass can approach lightspeed, if it did it would contain more energy(and thus mass)than is in the Universe(IE it would be a more massive Black Hole than the one it was hovering over). No, there's no hovering possible for anything with mass. And photons always travel at light speed. Even if emitted at 1.5 S they will leave that surface at lightspeed, if inside that radius they will never leave as all vectors lead into the BH. But whatever, it will do it at lightspeed. Photons are not particles, they are not matter, they are packets of energy and they travel through spacetime at lightspeed NO MATTER WHAT. You can alter their spectrum and energy, you can bend their path with gravity or electro-magnetic fields but you will not effect their speed through spacetime because both time and space will warp to the extent and in the direction necessary to make it so.

The value we give for that speed is arbitrary, but the actual speed itself is necessary. It is built into spacetime itself and cannot be altered in any way by anything within spacetime, not even Black Holes. The light we measure coming from BHs travels at exactly lightspeed, even those photons coming from very close to the EH. Their spectrums are gravitationally red shifted, their energy is less, but they are not slowed down by gravity.

Grumpy

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You misunderstand. I do know that nothing with mass can ever reach "c " ...The fish was an analogy....the river was an analogy also....The fish = photon/light......The river= space/time.
Space/time at the EH is flowing at "c" towards the Singularity. A photon emitted at that EH is also natuarally travelling at "c" away from the BH. Therefor the photon from a local FoR, does appear to hover, never quite escaping, and never getting sucked into the BH and Singularity.

 

It’s not enough to merely claim that all GR physicists/experts are wrong when they state this fact. You have to give a proof. Something to justify not only why the derivations are wrong but also why the experimental evidence is also wrong. Would you care to provide proof of your claim? That's why I didn't play this silly game with you.

I’ve already explained to you why you’re wrong and told you the experiment which demonstrated this. So please don’t make any more false claims or post more misinformation until you actually pick up a general relativity textbook and learn why you’re so wrong. Otherwise your claims are just ignorant.

At this point I've already explained the commonly accepted fact that the coordinate speed of light changes in a gravitational field and there are not other speeds since a proper speed cannot be defined for light. This is not to say that the locally measured value varies either. I've shown you how to derive this and you've provided no argument or proof that the derivation is faulty. I've explained that the Shapiro time delay demonstrates that the coordinate speed of light varies and that's experimental evidence for the varying of the speed of light by gravity. I've proven this twice already and all you've been able to do is repeat yourself. Since that's not what science is I'm won't bother correcting you again on this - you're wrong - accept it.

The only other opinion acceptable is to not speak of anything other than the locally measured speed of light which is a constant. That's Steve Carlip's approach and some physicists take that approach. But that's different than saying that Einstein (or more recently, Ohanian & Ruffini) was wrong.

 

Grumpy, your above post seems to intermingle theory and fact.., what is believed to be so and what is known to be so, as if it were all known or proven fact.

DO NOT TAKE ANY OF THE FOLLOWING TO MEAN THAT I DO NOT AGREE WITH CURRENTLY ACCEPTED THEORY. My intent is only to emphasize the line between what we know and what we think we know.

The speed of light, to the best of my knowledge has only ever been accurately measured in vacuum, in laboratory environments here on earth. An essentially flat spacetime environment. All astronomical measurements are based on assumptions, which in turn depend on the velocity and path of light...

While time dilation of clocks has been proven both within the context of SR and GR, length contraction has never been directly measured and thus remains implied as a requirement of the underlying theory. Put the lab some 20,000 miles in orbit with an atomic clock and measure the speed of light and then we might move the universal nature of the speed of light from theory to measured fact.

Please provide a reference for light measured coming from a black hole event horizon.

We observe and measure the kinetic interaction of objects, usually stars and at times perhaps plasmas, as they are affected by the presence of a gravitational field consistent with a black hole.., but as yet no one has seen a black hole or the event horizon.

Neither GR or QM provides any conclusive description of exactly what a black hole is, other than that it represents the center of a gravity well consistent with prediction. Even gravity itself defies our ability to present a compelling description of any fundamental mechanism.

Spacetime is an abstract description of the dynamics of gravitationally interacting objects. In that it has been a successful predictive tool and yet it describes reality only to the extent that it accurately describes the interaction of objects, influenced by gravity. Spacetime as a 4D model is a subjective relativistic perspective. It is a tool we use to communicate...

You are right about anything with mass (assuming an object with atomic and molecular structure) attaining a velocity equal to the speed of light, but you are wrong about it becoming a black hole. There is no connection between the archaic term "relativistic mass" and gravitational mass.., momentum has not as yet proven to increase an object's gravitational mass.

That said you are again right in stating that no massive object could reach the speed of light, again assuming by massive we are speaking of an object with atomic and molecular structure. It is likely that long before any atom, or object composed of atoms, reached the speed of light it would have become ionized and no longer exist as the object it began as... What this has to do with the hypotheticals used to present the subject being discussed to a lay audience is beyond me. I am fairly certain no one believes anyone has ever or would ever hover at the event horizon of a black hole. Not sure the human race has enough time to develop the required technology, prior to it demise.

Part of the problem it seems to me with discussions involving this kind of physics is that they are almost always approached from the perspective of GR, and then reach into areas where answers will almost certainly be found within the context of QM... And GR and QM still don't get along well enough for any real solution. Even within the purely professional theoretical landscape there are differences of approach and opinion. And while there are useful analogies and hypotheticals for some of the GR related issues and predictions, there is insufficient consensus within the QM community for any similar useful lay oriented explanations.

 

... and if it did, it would imply that the Lorentz rotation, which accounts for the contraction/dilation, would become unstable, that is, there would be a feedback loop within GR itself that would make it "a self-eating watermelon".

. . . and that's a consequence of space itself, and its intrinsic relationship to time through the Lorentz rotation.

So for example we get red and blue shift and the curved trajectory of gravitational lensing -- but never changes in the speed itself.

I wondered why he said that. On the longitudinal axis, the blackhole can send red or blue shift, but the only thing that's slowed is the apparently frozen motion near the horizon, which is known to spiraling inward. But the image itself transmits at exactly c. The rotation that appears to be frozen is on the transverse plane, and there's no way to evaluate the speed of light in that direction.

Which is exactly what the Lorentz rotation accounts for. If we take away the invariance of c, then the rotation falls apart, which means GR falls apart, which is what I meant by a self-eating watermelon.

. . . unless you believe the world is wrong?

Even taking on really small revisions to settled science takes enormous chops and new data. But this is a biggie.

Yeah, and with half a century of playing games with satellites, there would have been ample opportunity to construct a "light version" of Gravity Probe B, at a fraction of the cost. Hell, the time standards at NIST are now accurate enough to measure of few feet of gravity change. Imagine if those folks were told they are wrong! (I imagine them as highly anal folks who don't take anything lightly.)

That crossed my mind when he mentioned "observing light slowing down". That would require a "spectrum of velocities" which is ludicrous. Even if we wanted to speculate that's is possible in the vicinity of the horizon, it's meaningless to us and our telescopes which all exist in spaces that are ruled by v=c for the photon. That is, they would simply filter out "the other speeds".

That's a consequence of solving the Lorentz factor for v=c, resulting in division by zero. It's meaningless when multiplied by a zero mass; but any non-zero mass gives a mathematical singularity, which is the same as saying infinite energy would be required.

Which is restating the fact that c is the only thing that's constant in relativity.

Especially since the BH is just warping space and time in a relative way (to an observer).

Which is not at all the same as saying that "light slows down".


Just thought I would give this feedback since your line of reasoning was nearly identical to my own thoughts, almost point for point.

 

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There for a fish swimming radially directly away [against the flowing river] at "c" just at the horizon, would be seen to be stationary and hover from a local FoR, would it not?
_________________________________________________________________________________________________________

Again, I have never said or implied that anything with mass, can travel at "c".........Why even our intrepid friends Kirk, Spock, McCoy and company do not actually travel at "c"......They are only perceived to travel at "c" due to the manipulation of space/time itself. In other words it is space/time around the starship that is doing the moving, while the starship goes along for the ride. That also applies to distant galaxies and the extreme cosmological redshifts we observe.

Again, what I have said is that a photon will appear to hover at the EH, from a local FoR, because space/time is "falling"into the BH at "c" at that point, and the photon is trying to escape at "c" but never gets away from the EH, and never quite secumbing to the BH.

 

In reference to my previous post......
That photon of course [the one that appears to hover from a local FoR] must be emitted directly radially away.
Any other photon, will arc back and be swallowed by the BH from the local FoR.



http://casa.colorado.edu/~ajsh/singularity.html#r=1
Answer to the quiz question 1: False. Photons do not orbit in circles at the horizon, just skimming the surface. The place where photons orbit in circles is the photon sphere, at 1.5 Schwarzschild radii. Photons emitted at the horizon fall in; except that if a photon is emitted exactly vertically outward exactly at the horizon, then it will hover at the horizon, not moving at all.

 

Don't forget satellites, esp. GPS, which would not work if there was a new correction to be made for light speed differences.

I recall that there was a length contraction measurement done on a high speed ground vehicle at the flats in Utah.

By now GPS has proven all the groundwork of SR and GR.

I think that was pmb's claim.

Certainly not at the resolution implied by pmb.

It's pretty evident that they are dense objects consistent with neutron stars, also associated with jets and/or quasars/pulsars.

Sometimes it's used in the abstract sense and sometimes in a concrete sense, such as when measuring in light-years.

And the rest of most of it, which is empty and just transmitting light.

Or, as a 2D continuum which provides a useful way to analyze relativity.

Even an electron accelerated to c would require infinite energy.

Not to mention they're simply way too far away.

What threw me off was the recent argument over what appears to be semantics. Photons travel at a constant speed in all frames. The reason there are dark spots in the probable black holes already found is attributable to the distortion of the space in the vicinity of the predicted event horizon. it has been explained as a pinching-off of the light cone. More evident are the spirals seen in dust near apparent neutron stars, and galactic cores. Of course the findings of Gravity Probe B corroborate the Schwarzschild geometry, and GPS corroborates the Lorentz rotation in both SR and GR, so . . . the theory is doing pretty well. It's just not the same as saying c can vary in the vicinity of high mass.

 

Wow you're confused. I've explained to you why we require the measurement of the speed of light DIRECTLY measured in all local frames of reference to be c. I shouldn't have to explain that to you since you think your an expert. Now pay attention pete. It's because the tangent space of the differentiable manifold is linear and is a perfect representation of flat spacetime where the metric is minkowski

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

Guess what everybody who actually understands relativistic physics knows this. As in Prof Taylor and John Wheeler know this. Thats why it's in their undergraduate textbook. And the undergraduate textbook doesn't deal with the EFE but instead evaluates the spacetime with metric solutions to the EFE. So EBH tells the student about getting to use the metric of SR for 'doing' local physics. Since the tangent space metric is the metric of flat spacetime we generally 'get to use' the mathematics of SR to do the local physics. Evaluate direct spacetime event measurements conducted in the local proper frame where the measurement is made. Like the experiments conducted at CERN. A big 'hoorah' for Einstein's work of art. The remote bookkeeper evaluates the entire path from remote coordinates. The remote coordinate speed of light is frame dependent. The remote bookkeeper 'reckoning' accounts for spacetime curvature over the entire path. For an experiment like the great Shapiro delay they compare the path through curved spacetime with the same path evaluated with the Minkowski metric. The delay can be expressed as added distance associated with a path through curved spacetime. Any local measurement of the speed of light along the Shapiro experimental path would be measured in the tangent space and is required to be c. Over the remote path the spacetime curvature can be huge. Based on a coordinate singularity we say infinite at r=2M [integrate and it's finite]. The speed of light doesn't change over the remote path. The distance associated with the remote path is > an equivalent path through the tangent space. Flat spaetime. I'm not going to say it again and if you don't get it, for whatever reason, so be it.

 

You're right Grumpy [like that handle] gravity doesn't slow down the speed of light but it does increase the distance the light travels when compared with an equivalent path trough flat spacetime. That's why the remote bookkeeper reckons the speed of light slows down and comes to a halt at r=2M. The difference is really simple mathematically. In geometric units and Schwarzschild coordinates

dr/dt_shell = 1 [the metric confirms this]. Prediction for all local measurements.

dr/dt_bkkpr = 1 - 2M/r

2M/r is the curvature component of the metric. That's where the entire spacetime curvature is accounted for over the entire path [boundary to r=2M/r]. For the most part spacetime curvature is miniscule for local measurements. It's very small near the black hole also. The tangent space we approximate as flat is smaller in the strong field but definitely exists in a useful way. Probably can get 'a feel for this' looking at the Gravity Probe B experiment results for the directly measured [local measurement] geodetic effect. This is something I've thought about. I think the vacuum requirement was a sign of the times. GR wasn't written yet so we didn't know all stuff we needed to know to understand the predictions of combined theories GR and SR. Vacuum makes complete sense since having to pass through matter will increase the time required for the light to go from A to B. For me it never seems worth qualifying anymore. But that's me and it could be a bad choice. LOL. For me GR and SR are the same theory. We use different metrics to evaluate the physics. GR and SR are different aspects of the same differentiable geometry. The geometry we're using to model the Universe.

Have a good one

 

No one has ever directly measured the distance from the ground to a satellite, thus those real and/or assumed distances are subject to assumptions about the speed of light. GPS satellites are of no use for any relativistic test or experiment today. The first satellite launched did confirm to within a margin of error predicted time dilations of both SR and GR. After that the inboard clock was re calibrated and is dynamically resynchronized. All subsequent GPS satellites were adjusted prior to launch and are also dynamically synchronized. Yes the system works, but all that was confirmed were SR and GR time dilation predictions.

Come up with the reference. The length contraction associated with any land based vehicle would be unmeasurable, with any real degree of accuracy. Even then the measurements would have to have been remote measurements, since rulers do not retain a record of length contraction, the way clocks retain a record of time dilation. The way to prove length contraction would be to measure the speed of light at some distance remote from the surface of the earth with a time dilated clock. Not saying it isn't so, just that it has not yet been directly measured to be true.

See previous...

The second to the last sentence in Grumpy's post,

The light we measure coming from BHs travels at exactly lightspeed, even those photons coming from very close to the EH. ​

Spacetime is an abstract and relative coordinate system. It describes the dynamics of a system, not the mechanism behind those dynamics. If it did there would not be so much work going on trying to come up with a successful model of quantum gravity. In lay discussions and interpretations many theoretical aspects of theoretical physics, attain a measure concrete reality. We all tend to present what we know or think we know, with some measure of certainty.., which often then is interpreted as a description of reality. Most of what we are talking about is "Theoretical Physics"..., note the qualification that the "Theoretical" lends to the whole.

Note that the second sentence above should have read, "Photons travel at a constant speed in all inertial frames." The constancy of the speed of light is a locally measured constant. (Unproven in a globally defined manner as of yet.) Sometimes in the reference to c as a universal constant, the inertial frame of reference and/or locally measured, is lost.

Re: the comment involving, "the findings of Gravity Probe B corroborate the Schwarzschild geometry, may not be technically inaccurate, the Kerr metric, adding rotation to a Schwarzschild geometry, would have been a better reference. Still, though the Gravity Probe B experiment does confirm predictions of the Lense-Thirring effect, it does no more to define the fundamental mechanism(s) involved than the spacetime geometry from which the effect was predicted.

All of these are things we think we know, some are things we know we know. There is a difference between theory and observed reality. Between a mathematical proof and something experimentally proven. GP-B supports the underlying theory but does not raise it to the level of having proven that space itself is curved.