Black holes

[Ziggurat]

I'm afraid D'rok, that that description is almost totally accurate. The only thing I think it's worth pointing out is that some of the people here are mathematicians rather than physicists. There's nothing wrong with mathematics, and it's a vital tool for physics, but IMHO some people involved in physics sometimes attach more importance to mathematics than patent scientific evidence. What I'm trying to get across here re black holes concerns "non-real" solutions. For example if you need to carpet a square room which has a floor area of 16m², you can employ mathematics and work out that you need a carpet measuring 4m by 4m. However there is another solution to √16, namely -4. Mathematics does not tell you that a carpet measuring -4m by -4m is a non-real solution. It doesn't tell you that such a "negative carpet" does not actually exist. Whilst there's no problem with a negative displacement, distance is a scalar, and there is no such thing as a negative distance.

A -4m by -4 m carpet does exist. You just measure in the opposite direction. So... fail.

 

[Dancing David]

A -4m by -4 m carpet does exist. You just measure in the opposite direction. So... fail.

Oh you and your coordinate systems!

 

[Ziggurat]

Oh you and your coordinate systems!

It gets even better. If you measure a 4m x -4m carpet, you're only measuring the opposite way along one direction. Which means when you install it, you're actually going to install it upside down. Which is how you get a negative area. Measuring the opposite direction along both sides flips it back right side up.

The math works, you just need to know how to use it.

 

[ben m]

I'm going to get my Wacky Ruler Collection out of storage. According to my measurements, the carpet has one edge that runs from u=-3 to u=infinity (that's on my special "1/x" ruler) and another edge that runs from v=0 to v=3 (that's on my special "sqrt(9-x^2)" ruler).

Uh oh! I'd better not do any physics experiments on this carpet---thanks to my idiosyncratic rule choice, there's a corner of the carpet where the coordinate speed of light is anisotropic, being either zero or infinity depending which way you go.

Too bad there's not a way to transform from one ruler-choice to another---I'm tempted to try, but that'd be a "hop skip and a jump" over the truth, as revealed by my original choice of rulers.

 

[Farsight]

From the top of page 12:

Here's what you wrote:

F: I've read the original GR, and the scientific evidence squares with it. However it doesn't square with what people say GR says.

It's your claim, that "the scientific evidence" doesn't square with "what people say GR says".

If you can't, or won't, clarify what you mean by "what people say GR says", then there is no objective way for anyone to evaluate your claim (other than, perhaps, yourself), right?

The discussion here concerns black holes, where posters have said "GR tells us that the infalling observer doesn't notice anything unusual" or words to that effect. I maintain that GR does not in fact tell us that, and that the original "frozen star" black-hole description is correct. I've been making the case for that via a variable-speed-of-light argument backed with evidence to demonstrate that the Schwarzschild "coordinate singularity" is not merely a coordinate singularity that can be transformed away, but instead denotes a location where light does not propagate.

Here's the context:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
me: For example, you seem to think that two clocks, separated by a foot or so in elevation are (must be?) in the same reference frame; i.e. that they can both measure 'local' time and that the 'local' is the same.

you: No. They're just two clocks at different elevations. They're in this room. Or if you prefer, they're in space near a planet. The things we call reference frames are "artefacts of measurement" that have no physical existence.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Again, a reference frame is an abstract thing, not an actual thing in which clocks are located.

I think we're going to have to go deeper here, in order to make sure the terms each of us uses have the same meaning (to each of us). Let's take some, apparently simple, terms.

OK.

velocity: can you measure velocity? does it have physical existence? can you point up to the clear night sky and say Look, that's a star. It has a velocity of {x}?

I can say that the star has a velocity relative to me, or relative to something else. I can deduce this via measurement of redshift, though at larger scales this is complicated by the expansion of the universe. Velocity exists like motion exists: a bullet moving fast relative to you will kill you. A bullet at rest with respect to you will not.

gravitational potential: can you measure gravitational potential? does it have physical existence? can you point up to the clear night sky and say Look, that's a star. It has a gravitational potential of {x}?

It's a phrase we use to in conjunction with a gravitational field, which definitely exists. If it didn't, you wouldn't fall down. Note however that a gravitational field is a region where there is a gradient in gravitational potential. You could place two clocks within voids at the centre of two large but unequal masses. In these voids the clocks don't fall down, but they do tick at different rates because the conditions we label as gravitational potential are not the same. The clocks ticking at different rates tells us that gravitational potential does label something very real.

temperature: can you measure temperature? does it have physical existence? can you point up to the clear night sky and say Look, that's a star. It has a temperature of {x}?

You can measure the temperature of the surface of a star, but temperature is an emergent property of motion. It's a measure that gives, for example, a measure of the average kinetic energy of gas molecules. See temperature on wikipedia. Temperature exists like heat exists: grab hold of the wrong end of a red-hot poker, and it burns you.

wavelength: can you measure wavelength? does it have physical existence? can you point up to the clear night sky and say Look, that's a star. It has a wavelength of {x}?

Yes, you can measure it, and it has a real existence. All you need to do is look at the ocean to confirm that. A star doesn’t have a wavelength, but the light it emits does.

elevation: can you measure elevation? does it have physical existence? can you point up to the clear night sky and say Look, that's a star. It has an elevation of {x}?

Elevation is a name we use when describing distance from the ground or some other surface. That distance is real. The word does not apply to a star. Note that elevation is also used to describe an angle.

How do you do that?

You turn the clock over, and you undo the screws and take the back off to reveal the mechanism called a “motion”. You see cogs moving, not time flowing.

To be concrete, take a radioisotope clock. How do you "look inside" such a clock? Once you've looked inside one, how do you "look at what it actually does measure"?

I don’t know of any actual radioisotope clocks. Certain radioactive isotopes with a known half-life are used for dating, and these are referred to as clocks, but they aren’t clocks in the usual sense.

Evidence?

I cannot supply evidence for the absence of evidence to support the Hawking radiation hypothesis. Nor can I supply evidence to support the lack of evidence for fairies.

My algebra is rather weak; how can you derive Z₀ from c?

It’s a simple expression. Do your own research.

And is the impedance of space the same as vacuum impedance?

Yes.

I'll start more slowly, with just one, simple, question: what "electromagnetic waves" do you get by the annihilation of an electron and a positron?

It depends on their relative motion, but the typical result is two 511keV electromagnetic waves emitted in opposite directions. See for example this picture.

No. But let's do a simple experiment, shall we? Would you be so kind, dear reader of this post (and JREF member), as to tell us all (by writing a post) if I am boring you to death? Thank you.

This post has taken me an hour, it's very long, and it isn't relevant to the point of discussion. Large irrelevant posts are a known tactics for trashing a thread, and I reserve the right to refuse to respond to similar posts.

ETA: also, if you wouldn't mind, do you understand what Farsight has written (Impedance is an electrical property of say a cable, but it applies to space too, which electromagnetic waves propagate through. It applies to alternating current rather than direct current, these both being associated with conduction current, which is the motion of charged particles. You can create such charged particles via pair production, and get the electromagnetic waves back again via annihilation. Those electromagnetic waves are displacement current rather than conduction current, and they wave. They're alternating.)?

I would urge all readers to follow the links to verify that I’m referring to robust experimental physics, and that I haven’t written anything mysterious or unusual.

 

[Farsight]

Farsight, that's probably the 10th time you've pulled this nonsense. "Everyone sees you're wrong". "You've got no argument, and everyone knows it". "I have a psychic link to all of the lurkers on this thread, and there are 17 people laughing at you RIGHT NOW." I don't know how long you've been leaning on this rhetorical trick, but please retire it right now.

OK. But note this: I'm supplying the evidence, and the rationale. It isn't moonshine, it's mundane, and it's robust experimental physics. You aren't countering it with contrary evidence or an alternative rationale. All you're doing is saying "Farsight you're wrong because you don't agree with my textbook and my friends". You retire that too.

 

[Ziggurat]

You can measure the temperature of the surface of a star, but temperature is an emergent property of motion. It's a measure that gives, for example, a measure of the average kinetic energy of gas molecules. See temperature on wikipedia. Temperature exists like heat exists: grab hold of the wrong end of a red-hot poker, and it burns you.

You are wrong. Temperature is an abstraction, that involves entropy and its derivative. You cannot measure temperature directly, you can only ever infer it from other properties through the use of theory. And you're wrong about what that theory is: the average kinetic energy of a gas molecule being proportional to temperature is a result of the true definition of temperature which only holds true given a number of other assumptions which are not always true.

Temperature is no more real than a reference frame is. Hell, it even exhibits some of the strangeness that we're dealing with here, including singularities and infinities and even negatives. Yes, that's correct: there are systems which support negative absolute temperatures as well as infinite temperatures and even discontinuities in temperature.

 

[Ziggurat]

OK. But note this: I'm supplying the evidence, and the rationale. It isn't moonshine, it's mundane, and it's robust experimental physics. You aren't countering it with contrary evidence or an alternative rationale. All you're doing is saying "Farsight you're wrong because you don't agree with my textbook and my friends". You retire that too.

But you're not supplying evidence. Every bit of evidence that you have supplied matches the predictions of standard textbook theory which you claim is wrong. But how can you prove the theory is wrong if its predictions match the experimental evidence you provide? Obviously, you cannot.

If you want to prove that the standard interpretation of the theory is wrong, you need to provide evidence that contradicts the predictions of the theory. You have not done so. All you've done is present your interpretation of the evidence, and claim that since your interpretation contradicts the standard interpretation, the standard theory is wrong. But it doesn't work that way. The evidence itself still matches, the standard theory still stands.

 

[Farsight]

Thanks for the clarification....

Clearly we need to spend more time on this "scientific evidence"....

Yep, more time on this is needed....The only "scientific evidence offered by that experimental physics" that you've offered, so far*, is one optical clock 'running slower' than another, the two clocks being separated by ~a foot in elevation.

And the Shapiro delay, and the GPS clock adjustment. Apologies but no, I politely decline to repeat it.

As far as I know, this "scientific evidence offered by that experimental physics" is consistent with GR. If so, then the breakdown in communication is, pace you, that I cannot "follow the reasoning [you] offer".

Very little reasoning is required. You merely consider two parallel-mirror light clocks at different elevations, you're aware that GR predicts that these clocks do not stay synchronised, and then you draw yourself a picture showing one beam of light moving faster than the other. Like this:

|---|
|---|

Of course, it may well be that this "scientific evidence offered by that experimental physics" is inconsistent with FGR, but since I don't know what FGR is (and I suspect few, if any, others reading this thread do either), we're back to a failure to follow the reasoning you offer (and not, to repeat, the scientific evidence).

See above. One needs somewhat perverse reasoning to assert that the two light beams are moving at the same speed. If they were, the two clocks would remain synchronised, contrary to Einstein's GR prediction which has been verified repeatedly.

 

[ben m]

OK. But note this: I'm supplying the evidence, and the rationale. It isn't moonshine, it's mundane, and it's robust experimental physics. You aren't countering it with contrary evidence or an alternative rationale. All you're doing is saying "Farsight you're wrong because you don't agree with my textbook and my friends". You retire that too.

I disagree that you've supplied "robust experimental physics". For the third time: every experiment I know of is consistent with GR. You have not identified an actual experiment (as opposed to a thought experiment) where normal-GR fails to predict the results and FGR succeeds.

I disagree that I am not "countering it" with an "alternative rationale". Your argument is attaching special meaning to a particular choice of clock and ruler, and my argument is that that choice is arbitrary, that your interpretation of this clock's ticks is incorrect. (And, as an aside, widely recognized as an easy undergrad-level mistake.) I have no idea what makes you repeatedly label this as "not countering it". I understand the idea of disagreeing with this counterargument, but you keep announcing that it never existed.

Why is this basically the same as Sol/Clinger/Zig/etc.'s argument? Is that evidence of collusion, cliquishness, or blind-book-reading? No. If you were to post something saying "I think Pythagoras was wrong about a^2+b^2 = c^2", it's likely that three people would call you a crackpot, Clinger or Sol or DRD would post valid proofs that you're wrong, and I'd say "Farsight, you're wrong, I agree with my textbook and my friends". As I do here.

 

[ctamblyn]

That's pretty cool (the "short page")!

It's not a bad little article. I first came across it during the days of Farsight's first posts here (around March 2010), while having a discussion uncannily similar to parts of the present one.

It's also worth pointing out that the Ye and Lin paper (cited by Farsight) suggests simplified methods of analyzing astronomical gravitational lensing observations (so it may have considerable practical utility), could lead to testable hypotheses concerning the nature of the observed gravitational lensing signals, explicitly states that the "inhomogeneous vacuum" is not exactly equivalent to GR (pace Farsight), and concludes with this sentence: "We anticipate our work to be a stimulus to the quantum vacuum based investigation of the gravitational force."

Yes, and so despite the fact that the paper is pretty interesting in its own right, I don't see how Farsight can claim that it supports his position that he is merely reinterpreting GR.

Oh, and thanks for taking the time and trouble to answer my questions.

No trouble at all.

 

[DeiRenDopa]

My algebra is rather weak; how can you derive Z0 from c?

It’s a simple expression. Do your own research.

For those who've lost the plot, here is the set of exchanges which led to this:

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Farsight: And please note that I've mentioned vacuum impedance before now.

me: What is Farsight referring to?

Farsight: The impedance of free space, usually written as Z₀ = √(μ₀/ε₀). It's described as a constant, but it isn't actually constant. Remember those light beams? The speed of light c = √(1/ε₀μ₀). Do your own research. Think for yourself.

me: Right.

But my question was, and still is, what is it about vacuum impedance that "mentioned before now"? How is it relevant?

And what you write here doesn't help much. "It's described as a constant, but it isn't actually constant" - that's your claim, but you don't actually provide any evidence to support it, do you?

Farsight: Impedance is an electrical property of say a cable, but it applies to space too, which electromagnetic waves propagate through.

me: How does one measure the impedance of space? And is the impedance of space the same as vacuum impedance?

Farsight: You measure the speed of light then apply c = √(1/ε₀μ₀) and Z₀ = √(μ₀/ε₀).

me: My algebra is rather weak; how can you derive Z₀ from c?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

So, my algebra gives me this:

Z₀ = μ₀*c

and

Z₀ = 1/(c*ε₀)

So, I can certainly derive Z₀ from c ... provided I know either μ₀ or ε₀.

But, Farsight, you have not said how either μ₀ or ε₀ can be measured. Nor have you said how Z₀ can be measured.

After all this time, and all these posts, and no answer to my simple question?

 

[ben m]

And the Shapiro delay, and the GPS clock adjustment. Apologies but no, I politely decline to repeat it.

The Shapiro delay is correctly predicted by normal, coordinate-system-independent GR. The GPS clock adjustment is correctly predicted by normal, coordinate-system-independent GR.

 

[Farsight]

Substantive points only ...

We may have a problem here Houston...

Or not; can you explain how we "time it [the back-and-forth travel time, in some Fizeau-like set-up] using the distant pulsar"? ...

So, the whole point of my question was to try to find a way - that Farsight and I could agree - to measure the local speed of light.

The entire research program I've outlined, so far, is aimed at local measurements, and at understanding how they can be modeled...

What Farsight has done, with this last post, is move the goalposts, to examine things beyond the scope of the clearly stated program. For sure, those things are quite interesting, and well worth examining. But let's not get ahead of ourselves, shall we?

I haven't moved the goalposts. You have. You have introduced the word "local" in your post #449. When we follow your "This began" link back to post #381 the word "local" is not present.

So, back to my question: how do you use a distant pulsar to measure the local speed of light?

See post #403 where you said "I'm going to table this disagreement for now, and focus on your proposal concerning how to measure the speed of light, using a distant pulsar". You're now asserting you were asking how to measure the local speed of light.

You measure the speed of light with a Foucault-Fizeau device over a distance which you measured with your tape measure, timing it with your pulsar clock. If you time it with your parallel-mirror light clock, you are using the motion of light to time the motion of light, hence you will never measure any change in the speed of light.

Dear readers of this thread, are you "now conversant with [my] attempt to obscure the issue at hand"?

The futility of using some form of electromagnetic device to time the light's travel time is hopefully now even clearer.

 

[Farsight]

I agree that my reference frame is not the same as your reference frame, because my reference frame is not inertial. But I have no reason to conclude that the curvature of your trajectory is not real. It is real, in my reference frame. There is no experiment I can perform which contradicts this.

There is. You accelerate and note that my apparent trajectory changes immediately, before light can have propagated between us. That informs you that my trajectory cannot have changed, but only appears to have changed because you have changed your state of motion. Another way to establish reality is to have different orthogonal observers accelerate and have them compare notes. They disagree about my trajectory, just as they disagree about the orientation of my length contraction. After some discussion, they agree that their different observations are the result of their different motion relative to me.

No, I don't think you will.

I will.

 

[DeiRenDopa]

Just a quick comment on just one part of just one of Farsight's recent posts ... (bold added)

Very little reasoning is required. You merely consider two parallel-mirror light clocks at different elevations, you're aware that GR predicts that these clocks do not stay synchronised, and then you draw yourself a picture showing one beam of light moving faster than the other. Like this:

|---|
|---|

See above. One needs somewhat perverse reasoning to assert that the two light beams are moving at the same speed.

Thanks for making your reasoning so starkly clear.

Let's tease this apart, to see where you have gone off the rails are making claims inconsistent with hard experimental/scientific results.

First, "the two light beams" are not co-located.

That makes the picture inaccurate.

Second, the "two parallel-mirror light clocks [are] at different elevations".

That makes the picture wrong.

Third, "GR predicts that these clocks do not stay synchronised" confirms that the picture is wrong.

At the heart of GR is a simple word, relativity. There are many equivalent ways to describe what "relativity" is, in GR (and in SR).

No matter which of those ways you choose, they all lead, using iron-clad reasoning, to the conclusion that the picture is wrong.

Fourth, consider "the two light beams are not moving at the same speed".

What is "speed"? Why it's distance over time*.

And how does one measure distance? Why with a ruler. Preferably a ruler calibrated according the SI definition of the meter. A ruler which is co-located with the parallel-mirror light clock. Since there are two such clocks, we need two such rulers.

What about time, how does one measure time? Why with a clock. Preferably a clock calibrated according to the SI definition of the second. A clock which is co-located with the parallel-mirror light clock. Since there are two such clocks, we need two such clocks.

So, when we measure the speed of the two light beams, we find that they are, pace Farsight, moving at the same speed!

This confirms that the picture is wrong.

If they were, the two clocks would remain synchronised, contrary to Einstein's GR prediction which has been verified repeatedly.

Since they're not (moving at different speeds), the result is not contrary to Einstein's GR prediction.

* not accurate, but good enough for this post

 

[Ziggurat]

There is. You accelerate and note that my apparent trajectory changes immediately, before light can have propagated between us. That informs you that my trajectory cannot have changed, but only appears to have changed because you have changed your state of motion.

Let's say you and I are far away from each other, but initially at rest with respect to each other. I accelerate towards you for a short period of time, and then stop accelerating. You are now moving with respect to me. You began moving with respect to me as soon as I started moving. That change also propagated faster than light. That informs us that your velocity is not real.

You cannot actually reconcile this position with relativity. Your position requires making motion absolute.

Another way to establish reality is to have different orthogonal observers accelerate and have them compare notes. They disagree about my trajectory, just as they disagree about the orientation of my length contraction. After some discussion, they agree that their different observations are the result of their different motion relative to me.

We can also have different observers who are all in uniform, unaccelerated motion with respect to each other. They too will disagree about each others' trajectories. After some discussion, they will also agree that their different observations of each others' velocities are the result of their different motion relative to each other. Hence, we can conclude that their differing velocities are not real. Each observer cannot actually have multiple real velocities. They can only have one real velocity, which means that motion is absolute.

That's the logic you're using.

 

[Farsight]

It's a "delay" in the sense that light takes longer to travel the path than it would if the star were not there.

Just as it's a "delay" if your train spent part of its journey travelling at 50mph rather than its usual 60mph. Just take the evidence at face value.

And, that delay is only evident in a non-local measurement (propagation of light between distant points).

Of course. If you followed the path of the Shapiro radar signal in your gedanken spaceship carrying a parallel-mirror light clock and your metre rod, at no point in your journey will you measure a reduced speed of light. Where the speed of light is reduced, it is also reduced in your parallel-mirror-light clock. It's similarly reduced in your optical clock, your microwave atomic clock, your UV optical clock, and so on.

Be careful to note what what I'm actually referring to here. I'm talking about a measurement made by a physicist in a freely falling laboratory. A local measurement, in contrast to the the non-local measurement I mentioned earlier in my post. Such physicists will always measure 299792458 m/s, and that is the value we denote by "c". It is that value which appears in Maxwell's equations (in vacuo) and the formulae for Z₀ and c in terms of μ₀ and ε₀.

I know. Let me give you a simple analogy that hopefully brings it home: you're a clockwork man, and you hold a clockwork clock. It ticks at a certain rate, and when you plunge it in an oil bath, it ticks slower. Now jump in after it.

Electromagetism, at the classical level, is described by Maxwell's equations. And in that context, c and μ₀ are just constants resulting from the particular choice of units. So, whatever you're talking about here is not classical electromagnetism.

General relativity postdates classical electromagnetism. What I'm talking about here is the route to unification.

If you assume that c and μ₀ are varying through space, then it is quite clearly possible that they could vary in such a way that Z₀ remains constant.

I disagree with that. Electromagnetism is an example of unification, the field concerned is the electromagnetic field rather than distinct electric and magnetic fields. Just as the electric field is one "aspect" of the electromagnetic field whilst the magnetic field is another, ε₀ is one aspect of a quality of space whilst μ₀ is another. The best word I can find for this is the "strength" of space. You see hints of this from time to time. For example see Mordehai Milgrom's New Physics at Low Accelerations (MOND): an Alternative to Dark Matter at http://arxiv.org/abs/0912.2678 where you can read this on page 5:

"We see that the modification of GR entailed by MOND does not enter here by modifying the ‘elasticity’ of spacetime (except perhaps its strength), as is done in f(R) theories and the like."

I don't think MOND is quite right by the way, but I don't think dark matter is particulate in nature. That's one for another day.

It is also possible that c and Z₀ vary while μ₀ remains constant, and so on.

As above.

So, you do need to specify how it changes from place to place, otherwise there is no way to know whether your claim was true.

I reiterate that all I need to do is show that some quality of space changes affecting the propagation speed of light.

I'm familiar enough with gravitational lensing for present purposes. As it is perfectly well accomodated by the standard, modern understanding of GR in which c, Z₀ and μ₀ are a constants, you cannot appeal to the existence of lensing to prove the superiority of your model.

It's not my model, GR started life with a variable speed of light, but it's been airbrushed out of history. Look at those Einstein quotes in post #412, I'm not lying about them. I meant what I said about GR being the sleeping beauty. You go back to what Einstein actually said, you read A world without time, you take the light-clock evidence at face value and say it's light moving instead of time flowing, and the pieces start fitting together.

They do not demonstrate equivalence, merely close similarity in certain limited circumstances (though they reproduce some correct results for a static gravitational field). You are claiming complete equivalence.

I never said that. Don't forget that Einstein referred to inhomogeneous space in his Leyden Address. Everybody now talks about curved spacetime, but Einstein didn't. He talks about curvature, but I can't actually find him talking about curved spacetime. It's something to do with the Golden Age and its paradigm shifts. Read Peter M Brown's essay at http://arxiv.org/abs/physics/0204044 . It isn't peer reviewed, but it's well worth reading.

You should read this short page for more information on that general "refractive index" approach (and why it falls down): http://mathpages.com/rr/s8-04/8-04.htm

I skimmed it, it's unconvincing, a bit of a straw man I'd say. See this:

"It’s also worth noting that physical refraction is ordinarily dependent on the frequency of the light, whereas gravitational deflection is not, so even a formal match between the two relies on the physically implausible assumption of refractive index that is independent of frequency".

Again, a model in which only a single (ETA: scalar) quantity (in their case, a refractive index they denote by "n") is varying from point to point cannot logically be equivalent to GR in all its gory detail.

But it's a start. Einstein mentioned Huygens in The Foundation of The General Theory of Relativity.

What Einstein believed from 1911-1915 doesn't matter for this discussion. What we have in front of us is (a) the modern understanding of GR, and (b) your claim that GR's predictions can be reproduced by assuming that c and/or Z₀ vary from point to point.

It matters because people say "GR tells us" when it's very different to what Einstein actually said. I'm sorry, but that matters to me.

It's worth noting that Puthoff's model is not a reinterpretation of GR. It is a different model with different predictions. What we're discussing here is, purportedly at least, classical GR.

Noted.

I'm familar with annihilation and pair production. They are well understood within the framework of the Standard Model. You do not need any understanding of particle physics in order to understand GR (i.e. standard GR).

They aren't well understood at all. Honestly. But that's another one for another day. And I'd say one needs an understanding of everything to take things forward. Then you can see how to join the dots.

So, if FGR (as I see it has been christened) depends on the nature of particles to ensure that all clocks are affected exactly equally by gravity, then it cannot be the same thing as standard GR.

Standard GR isn't the same thing as Einstein's GR. As to what I've been telling you, clocks are made of particles, and light is what it is. They don't go slower for nothing, or because of some mystical magic. A massive body "conditions" the surrounding space like Einstein said. It changes it, the change diminishing with distance. Anyway, don't call it FGR, call it relativity+. I'm an IT guy, the name was apt.

And let's not forget that we were talking about black holes. I hope some of the guys here are starting to understand the frozen-star interpretation a bit better now. It's not some my-theory woo, it's what Oppenheimer called them. The modern equivalent is the gravastar, and the "stuff" it's made of is weird primal stuff. Much more interesting than a give-up-and-go-home point singularity.

I must go. Nice talking to you ct. Somebody please explain to Zig abut the difference between distance and displacement.

 

[Ziggurat]

Somebody please explain to Zig abut the difference between distance and displacement.

I'm perfectly aware of the difference. You, however, are not. Your scenaro explicitly relies on displacement, not distance. Without displacement, the orthogonality implicit in your 4mx4m square, and the area calculation of it, isn't possible. So fail again.

You have nothing, Farsight. Every actual experimental result you refer to matches standard modern general relativity. Many of the results (such as Gravity Probe B) cannot be explained by any scalar GR substitute which you seem attracted to. The only real objection is that you think certain mathematical operations of the theory (such as coordinate tansformations) are invalid. But you have no basis for this conclusion, since none of these transformations change any of the tested predictions of modern GR (which, again, are all accurate). And you haven't claimed that there is any mathematical problem with the transforms either. So you have no physical justification for your objection, and you have no mathematical justification for your objection. You have no objection other than that certain results offend your sensibilities, and you don't trust math. That isn't much to hang your complaints on.

 

[DeiRenDopa]

Quite a few posts by Farsight today, several with some meaty responses; thanks Farsight.

Four quick follow-ons:

How do you do that?

You turn the clock over, and you undo the screws and take the back off to reveal the mechanism called a “motion”. You see cogs moving, not time flowing.

Not very helpful, and I don't know why you even bothered to waste your time writing this.

Several types of clock without cogs have already been mentioned in this thread (so your response is hardly complete), and you've not addressed my comments concerning "motion"^.

To be concrete, take a radioisotope clock. How do you "look inside" such a clock? Once you've looked inside one, how do you "look at what it actually does measure"?

I don’t know of any actual radioisotope clocks. Certain radioactive isotopes with a known half-life are used for dating, and these are referred to as clocks, but they aren’t clocks in the usual sense.

I am tempted, sorely, to quote your own words back to you, Farsight (about doing some simple research).

Anyway, all we need, for the purposes of this part of the current discussion, is a clock which a) measures time the same as a parallel-light clock, a P-LC (i.e. keeps synchronized with such a P-LC, when the two are co-located), and b) does not rely on "some form of electromagnetic device" (whether "to time the light's travel time" or anything else).

Here is a (possibly incomplete) outline of just such a (radioisotope) clock (RIC, for short):

* a quantity of a radioisotope with well-understood properties (esp. half-life) is sitting on top of whatever emits the light pulse in the P-LC
* decays of this isotope are recorded, continuously, with a counter (the RIC counter)
* whatever triggers the P-LC to emit its first light-pulse also triggers (or perhaps resets) the RIC counter
* whatever registers the return of the first light-pulse also triggers a read-out of the RIC counter
* the difference between the two RIC counter readings is directly related to the time between the first and second readings
* it is, obviously, a measure of the same time interval as that between the emission and return of the first light pulse, in the P-LC
* calibration of the RIC is done by a device which measures the quantity of radioisotope

As the spontaneous decay of radioisotopes can occur due to several different mechanisms - some of which do not involve the electromagnetic force at all - a judicious choice of radioisotope, for use in the RIC, will ensure that the clock 'ticks' without any "motion" and without any electromagnetic waves.

There is at least one other kind of clock which 'ticks' without any "motion" and without any electromagnetic waves, a muon clock (MC). In many ways a MC works much like a RIC, though there are considerable differences in how to make one!

Evidence?

I cannot supply evidence for the absence of evidence to support the Hawking radiation hypothesis. Nor can I supply evidence to support the lack of evidence for fairies.

Of course you can't.

And I'm not so silly as to have asked for such evidence.

Here's what you claimed (I added bold): "There's no evidence for Hawking radiation, and yet it's bandied about as if it's settled science."

So, where is the evidence that the existence for Hawking radiation is "bandied about as if it's settled science"?

Clear now?

Rhetorical question: why do you, apparently, have so much difficulty understanding the simple, straight-forward questions I ask? I mean, it would seem - based on many posts, by others, in this thread that those others do not have such difficulties.

I'll start more slowly, with just one, simple, question: what "electromagnetic waves" do you get by the annihilation of an electron and a positron?

It depends on their relative motion, but the typical result is two 511keV electromagnetic waves emitted in opposite directions. See for example this picture.

Thanks.

I understand the relevant, hard, objective, experimental results to be consistent with the annihilation of an electron and a positron producing (typically) two 511keV photons.

In what respect(s) do you think these two photons behave like electromagnetic waves?

ETA: also, if you wouldn't mind, do you understand what Farsight has written (Impedance is an electrical property of say a cable, but it applies to space too, which electromagnetic waves propagate through. It applies to alternating current rather than direct current, these both being associated with conduction current, which is the motion of charged particles. You can create such charged particles via pair production, and get the electromagnetic waves back again via annihilation. Those electromagnetic waves are displacement current rather than conduction current, and they wave. They're alternating.)?

I would urge all readers to follow the links to verify that I’m referring to robust experimental physics, and that I haven’t written anything mysterious or unusual.

Several readers apparently have done just what you ask here, and have said (in effect) that what you wrote is indeed at least somewhat mysterious or unusual (or both).

^ nor others'