Black holes

[DeiRenDopa]

If anybody is still reading Dopa's posts, my advice is: don't. He hasn't conducted the gedankenexperiment using clocks calibrated against a distant pulsar, ...

(bold added)

Let me see if I can redeem myself in Farsight's eyes ...

Start with the key parts of the particular Gedankenexperiment in which I used Farsight's "distant pulsar" as calibration source.

Here are the key parts of that Gedankenexperiment:

Our lab is located on the surface of a perfectly spherical, non-rotating, solid, isodense planet which is a very long way from any other dense object (star, planet, etc). This planet has no atmosphere. The pulsar clock is located directly overhead, has no observable proper motion, and emits a light signal of stable 'ticks' (we verify this by observing it for many years, from a fixed location on the surface, and comparing the signal with a variety of local clocks, calibrated with equipment that is keyed to the SI definition of the second).

[...]

There are identical copies of all the equipment on a dozen or so ultra-light platforms, each platform attached to an ultra-light, vertical tower. The distance between each adjacent pair of platforms is the same, as measured by a ruler. The equipment on each platform includes a gravimeter, which measures the local g.

[...]

Oh, and I'm going to propose an interesting variation: each platform also has a (modified) pulsar clock! And there's one at the base of the tower too, along with yet another identical copy of all the equipment.

This modified pulsar clock is like Farsight's idealized one, in that the signal it emits is stable, and consists of periodic pulses (of identical shape).

Unlike Farsight's pulsar clock, the DRD pulsar clock (DPC, for short) emits at several, fixed, frequencies. These are 1 GHz, 1 THz, and 500 THz. The frequencies are calibrated using local instruments (and sources). Each DPC - they are identical, remember - emits continuously at each of these frequencies; the pulses (which form the 'ticks') are short-duration, many-hundred-fold increases in the otherwise constant intensity output.

Suppose, instead of "a dozen or so ultra-light platforms", we have a billion such platforms.

Each platform still houses a complete set of identical equipment/instruments; this time however, the "ultra-light, vertical tower" extends out (or up, if you prefer) a distance of 1 au*, or 1 pc**, or 1 Mpc (mega-parsec), ...

How do any of the (billion) observers' objective, independently verifiable experimental results differ, from what I described earlier^?

Well, the "pulsar" part is the same as in Farsight's posts, so the problem must be with "distant". Is 1 au "distant" enough? 1 pc?

That can't be it; the local speed of light - as measured using the Farsight method - is still dependent on which of the "distant pulsars" you use to time the light beam (or whatever).

To be sure, the difference between the speeds measured using two adjacent pulsar clocks - at 1 au or 1 pc, say - will be quite small ... but Farsight is not concerned with how small such a difference may be, he is concerned with "different elevations" and "staying synchronized" (source). And we could always increase the mass of our planet, and make it out of some super-strong material (so that it doesn't collapse to become a black hole), so the gravitational potential 1 au out would be quite different from that 1 pc out (or 1 pc vs 1 Mpc).

Farsight states (same source) "The speed of light varies. Experiment tells you this." And it does, if you apply his method, and logic.

But what he doesn't say is that, using the same method and logic, it also varies depending on which (standard) "distant pulsar" you use!

* astronomical unit; approximately the average distance between Earth and Sun
** parsec, approximately 3.3 light-years
^ "Using the Farsight method, the local speed of light not only varies with location, but depends upon which non-local clock you use to determine it."

 

[DeiRenDopa]

Yeah, that was hilarious. In fact, I think I may have gone through a debate like this with MM about temperature as well.

Temperature is particularly good for exposing such fuzzy thinking: it seems like such an ordinary quantity, and we're exposed to it so early and so frequently, that pretty much everyone inevitably makes some sort of internal conceptual model of what temperature is. But the true physics definition is necessarily much more subtle than the models people construct on their own (as well as what's possible to teach children), and if you can't learn to let go of your preconceptions and start thinking about the issue rigorously, then you'll never grasp the truth. So it's a great litmus test for cranks. Most people, cranks or not, don't know the real definition of temperature, but the non-cranks are willing to learn

One book I found which does seem to do a good job of explaining the definitions and subtleties is "Four Laws", by Peter Atkins. Some, but not much, understanding of mathematics is required; if you didn't flunk Math in your last year at high school, you should have no difficulty ...

Negative temperatures, and infinite ones (both positive and negative) really mess with your head, unless grasp what the definition of temperature actually is. As you say, a good crank test!

 

[tsig]

Perhaps he had different priorities, such as writing and promoting his book.

But you are right, and he could have been writing and publishing papers in credible journals instead.

---

(ETA: It seems this goes back to at least 2006. Note the last sentence of the opening post .)

From the post:

Oh yeah. If you don't believe me, if you think I'm wrong, prove it.

Show me the maths.

Reversing the burden of proof, "show me the maths" is laughable coming from someone who can't grasp negative numbers.

 

[ctamblyn]

The evidence that supports Einstein is right there in optical clocks losing synchronisation at different elevations. You know they'll each stay synchronised with parallel-mirror light clocks at those elevations, so you know that parallel-mirror light clocks at different elevations lose synchronistion. We can represent that like this:
(...snip...)

OK, I'm going to stop you there since the rest of your post is identical to material that you have presented several times elsewhere in this thread alone.

To be clear, I asked for empirical evidence that favours FGR over "MTW" GR. Gravitational redshift is predicted by "MTW" GR, as is the Shapiro delay and so on. "MTW" GR passes every relevant experimental test performed so far.

Please cite just one piece of empirical evidence that favours FGR over "MTW" GR, instead of repeating yourself yet again.

 

[ctamblyn]

It goes further than GR, which doesn't cover particle physics, but it is true to Einstein. See Einstein talking about the history of field theory in 1929 and pay attention to the "structures in space". See bits like this:

"The two types of field are causally linked in this theory, but still not fused to an identity. It can, however, scarcely be imagined that empty space has conditions or states of two essentially different kinds, and it is natural to suspect that this only appears to be so because the structure of the physical continuum is not completely described by the Riemannian metric".

But anyway, we aren't talking about me. We're talking about black holes, and how the patent scientific evidence for the variable speed of light, which was advocated by Einstein, favours the original "frozen star" interpretation rather than the "point singularity" interpretation.

I'm talking specifically about the claims you have made in this thread, and the fact that you cannot point to a single piece of relevant experimental evidence that contradicts "MTW" GR while simultaneously supporting FGR.

 

[Tubbythin]

This reminds me of the "discussion" we had with MM, on the Casimir effect, and the definition of pressure.

We had several of these conversations.

 

[ctamblyn]

(...snip...)
That I may have failed to understand your ideas is entirely possible; after all, in ~five years' of posting, it would seem very few (if any) others do understand your ideas.

Most people in such a situation would take that as pretty strong evidence that either their ideas were incoherent, or their presentation style was flawed. Unfortunately, Farsight/Mr. Duffield does not appear to have reached the same conclusion, presenting the same ideas in the same way as far back as you care to google.

But let's do a little test, shall we?

What do other readers of this thread make of my Gedankenexperiment (part I, part II, part III; you may need to click a few arrows to get all of it, especially the context)?

Specifically:
1) where, exactly, is it inconsistent with what Farsight has posted, so far?
2) irrespective of what Farsight may think, are there any flaws in it?
(...snip...)

Regarding question (1): Without more constructive participation and detail from Farsight it is hard to be certain. I think your Gedankenexperiment is consistent with what Farsight has posted so far on pulsar clocks. Then again, as sol invictus pointed out, Farsight has contradicted himself at least once in this thread, making attempts to understand his model especially difficult.

As for question (2): At higher elevations there would be a greater number of pulsar ticks between the emission of a photon at that elevation and its subsequent detection a centimetre (say) away - i.e. one tick of a P-MLC would take longer in terms of pulsar ticks. If c_Farsight is some setup-dependent constant divided by the number of pulsar ticks, c_Farsight should decrease with height. However, the diagrams you posted here suggested the opposite, unless I read them wrong or misunderstood something about the set-up (which is not unlikely). Those diagrams aside, the text itself looked alright to me.

 

[ctamblyn]

I'm not quite saying that every physical process can be reduced to electromagnetism. I have already said that nuclear clocks might show some discrepancy as compared to electromagnetic clocks. I don't think they will, but let's see what experimentation tells us.

Imagine we do a careful and rigorous series of experiments to test the synchronisation of nuclear and electromagnetic clocks at various altitudes. Now imagine these two possible outcomes: In the first, nuclear clocks are found to consistently lose synchronisation with electromagnetic ones. In the second, nuclear clocks are not found to go out-of-synch with electromagnetic ones.

In one possible future, your confidence in your position is strengthened. In the other, it is weakened.

Which is which?

IMHO it's better to say that all physical processes are affected because there is an underlying "unification" of the forces.

It is clear that FGR relies on unsupported hypotheses about the properties of fundamental particles in order to account for why weak and strong processes are affected by gravitation in the same way as electromagnetic ones. Standard GR, on the other hand, requires no such assumptions. Regardless of the correctness of either theory as applied to the physical world, it follows that FGR is not standard GR (whether according to Einstein in 1916 or Misner, Thorne and Wheeler in 1973).

 

[Reality Check]

You said outwards. See post #609. Touché.

Yes he said outwards from the (black) hole. I think that anyone can realize that outwards is the same as upwards (ETA in this case!).
A rocket launched on the Earth goes both upward from the ground) and outward from the center of the Earth.

 

[Reality Check]

Farsight, Show your math in FGR for the anomalous perihelion advance of Mercuty

Enough. I cannot respond adequately to somebody who says it's constant because I say it's constant and moreover is abusive and untruthful whilst dismissing scientific evidence and what Einstein actually said.

Enough. I canot respond adequately to somebody who is so ignorant of GR that they do not know the basics:

• The local speed of light c is the local speed of light in vacuum. It is constant.
• The coordinate speed of light depends on the coordinates used.
  In KS coordinates it is constant. In S coordinates it varies.

This person is "abusive and untruthful whilst dismissing scientific evidence and what Einstein actually said"!

I have never dismissed the scientific evidence. That evidence is that GR is correct.
I have dismissed you using that evidence for a fantasy of FGR.

So now all you have to do is produce the mathematics behind your idea, generate predictions, e.g. for the anomalous perihelion advance of Mercury, and show that the observations do not invalidate your theory.

Farsight, Show your calculations in FGR for the anomalous perihelion advance of Mercury.
This should be simple to do since it was the first thing that Einstein did even before the full publication of GR.

I have never dismissed what he said. I am dismissing your crackpot argument by authority because that is a logical fallacy.
I am also pointing out the several of the quotes you are obsessed with are from the period in which he was formulating GR.

The fact remains that GR is a coordinate free theory.


The fact remains that when you introduce coordinates then you get measurements that are for those coordinates. Thus the science that we (not you Farsight ) see explained in many GR textbooks:

• In Schwarzschild coordinates the coordinate speed of light is zero at the event horizon (there is a coordinate singularity there).
• In Kruskal–Szekeres coordinates the coordinate speed of light is the same everywhere (there is no coordinate singularity at the event horizon).

 

[Farsight]

LOL. We've got sol misunderstanding the principle of equivalence and trying to say we really do accelerate upwards, still fighting shy of saying what his expression describes, and offering to provide a circular "proof". We've got Zig calling me a crank whilst clinging to his risible negative carpet, and wilfully ignoring the Schwarzschild blowup and getting all pompous about temperature. We got Dopa accusing me of "fundamental misunderstanding of the relationship between physics and reality" whilst proposing a tedious gedankenexperiment that tries to subvert what I said into multiple speeds for the object of your choice. We've got ben telling us the sun goes round the earth because all coordinate systems are equally valid. We've got Clinger still hiding behind maths and doubtless wittering on about homework. We've got ct wilfully ignoring the scientific evidence and Einstein and trying to play the "your theory" card. Oh, and dishonestly backing Dopa's and getting gravitational time dilation back to front. And last and least we've got RC asking me about the perihelion advance of Mercury when I've repeatedly pointed out the Gerber controversy.

And still nobody will address the hard scientific evidence of the Shapiro delay and light clocks losing synchronisation at different elevations:

|------------------|
|------------------|

Nobody will concede that this demonstrates with crystal clarity that the speed of light is not constant. And nobody will concede that that's what Einstein said:

1911: If we call the velocity of light at the origin of co-ordinates co, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation c = co(1 + Φ/c²).

1912: On the other hand I am of the view that the principle of the constancy of the velocity of light can be maintained only insofar as one restricts oneself to spatio-temporal regions of constant gravitational potential.

1913: I arrived at the result that the velocity of light is not to be regarded as independent of the gravitational potential. Thus the principle of the constancy of the velocity of light is incompatible with the equivalence hypothesis.

1915: the writer of these lines is of the opinion that the theory of relativity is still in need of generalization, in the sense that the principle of the constancy of the velocity of light is to be abandoned.

1916: In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when die Ausbreitungs-geschwindigkeit des Lichtes mit dem Orte variiert [=the speed of light varies with the locality]. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust.

And you'd rather believe the sky's falling in rather than the evidence that proves that the original frozen star black hole interpetation is correct. Sheesh. I'm sure now that readers can appreciate why in Clifford M Will's paper we can read this:

"Although special relativity itself never benefited from the kind of 'crucial' experiments, such as the perihelion advance of Mercury and the deflection of light, that contributed so much to the initial acceptance of GR and to the fame of Einstein, the steady accumulation of experimental support, together with the successful merger of special relativity with quantum mechanics, led to its being accepted by mainstream physicists by the late 1920s"

And why in the golden age we can read this:

"The golden age of general relativity is the period roughly from 1960 to 1975 during which the study of general relativity,[1] which had previously been regarded as something of a curiosity, entered the mainstream of theoretical physics..."

Poor old Einstein. He must have had decades of "scepticism" from posturing quacks whose physics knowledge was scant. Bah. That's a wrap guys. You won't address the evidence, you have no counterargument, and you have no integrity. I win by a knockout. What do you want to talk about next?

 

[ben m]

LOL. We've got sol misunderstanding the principle of equivalence and trying to say we really do accelerate upwards, still fighting shy of saying what his expression describes,

HIS EXPRESSION DESCRIBES GEOMETRICALLY FLAT SPACETIME. Not in the coordinates you're used to, but in an alternative set of coordinates. He gives you a metric that tells you BOTH (a) that the spacetime is flat (as several better-educated posters derived on their own) and (b) how the coordinate-labels (x,y,z,t) are laid down in that spacetime.

Flat spacetime, Farsight. Like he told you five times. What else are you waiting for?

Well, I know what you're waiting for. You don't know enough about coordinates, geometry, or math to know whether or not Sol has given you enough information. You don't know enough about coordinates, geometry, or math to know whether his "it's flat spacetime" is a simple fact or a confusing bluff. So you're trying to stall until he says something you've heard before.

I have one memory from when I was in school, maybe 6th/7th grade, and learning algebra. My youngest sister, who must have been just learning to add or something, came up to me and said "I want to learn algebra too. What's x?" "x isn't one particular thing, it means something different in every problem," I said. "OK, what's a?" That's you, Farsight. You don't know what a metric is or what you can (or can't) do with it.

 

[W.D.Clinger]

what Farsight says about math: a compendium

In fact, any time a poster has to start resorting to "math isn't real", well, that's pretty much a guarantee that the poster is a crank. We see it time and time again, and it usually arises from people who can't even do the math.

The weird and entertaining thing about Farsight's argument is that his main argument here is almost entirely mathematical:

The Schwarzschild mathematics tells you something important, and when you disregard it you end up with a non-real solution.

And I repeat: take a look at this page from Misner/Thorne/Wheeler's Gravitation posted by a guy called Jesse. On the diagram on the left, the curve peaks to infinity at the event horizon. That's the gravitational time dilation tending to infinity, and coordinate time tending to forever. At the top of the peak, is the end of time, so there is no top to it. But it's "transformed away" using Kruskal-Szekeres coordinates. A mathematical conjuring trick is employed to do a hop skip and a jump over the end of time, by pretending that a stopped observer sitting in front of a stopped clock sees it ticking merrily away.

Farsight says he understands the mathematics of general relativity, and says he's willing to discuss that math:

What tosh, Mashuna. The expression is straightforward, I understand the mathematics, I've given the numbers, and I've supplied rock-solid scientific evidence. If you'd like me to repeat anything or explain it another way I'll only be too happy to do so.

Farsight says he accepts the relevance of mathematics to general relativity:

Not me, Clinger. I'm on record as saying mathematics is a vital tool for physics, and I have responded on mathematical points, as per this example. Yes I'm an iconoclast destroying dogma, but I'm doing it by pointing out the issues with the mathematics and giving scientific evidence to back that up.

Farsight has enough confidence in his own mathematical skills to say everyone else is getting the math wrong:

Your calculation is wrong. Whether you're at the event horizon or not, the speed of light is zero in all respects. Your "calculation" omits the undefined result at R=2M, it features a stopped observer and a stopped light-clock, and you mistakenly think that this observer sees the clock ticking normally. He does not. Light is stopped. He doesn't see anything.

The two situations are not the same. You're misinterpreting the mathematics used to describe a black hole because you're ignoring the undefined result at R=2M. Then you're claiming that the mathematics supports your description when it doesn't.

Change the record, Clinger. Taking refuge behind you don't understand the mathematics just isn't good enough.

...snip...

I'm right. Sol's wrong.

All: as ever Clinger has no argument, does not respond to the issue I raised, and tries to bury the discussion with mathematics that most readers don't follow. Don't buy it. It's smoke and mirrors, it's Emperor's New Clothes.

Your mathematical fact is fiction.

...snip...

Spare me your "mathematical fact", I deal in scientific fact. And I'm not seeing downward sunbeams travelling faster than their upward reflections.
I understand what you're saying. I understand why it's wrong.

...snip...

Your calculations are wrong from the off. Your axioms are flawed.

On the other hand, when people have challenged his math, Farsight has responded as though talking about math is a distraction or some kind of rhetorical trick:

When I come along with scientific evidence and a sound argument to challenge the hogwash, the fallback position is "you don't understand the mathematics". It's bull. Don't fall for it.

There you go hiding behind mathematics again. It cuts no ice, sol. You need to be able to support your case using plain English supported by scientific evidence. If you cannot, then people will conclude that you have no case.

If someone says you're wrong John, and here's the scientific evidence and the clearly-understandable explanation that says why you're wrong, I like to think I will examine it, discuss it sincerely, and then be man enough to eat humble pie. What I won't do is roll over when somebody like Clinger tries to pull the you don't understand the maths trick. IMHO it's the modern equivalent of you don't speak Latin.

Learn to see what's there instead of refusing to see it because your head is fog full of mathematical abstraction and artefact.

I'm presenting evidence for the original frozen star black hole interpretation, backed up by Einstein references and a solid argument. Clinger has no counter argument, and is trying blind you with maths and diss me instead.

Obscure maths questions are no substitute for addressing the scientific evidence, sol. You won't fool anybody with that. I don't speak Latin either.

What event horizon is that? I said I didn't know what this expression described. Care to enlighten me or are we all going to ignore reality and get lost in maths?

I understand it, and your mystery expression is no substitute for addressing scientific evidence. You can't blind 'em with maths. It isn't going to work any more.

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.

You're still hiding behind mathematics instead of addressing the evidence. And now you're hiding behind abuse? That's one way to end an argument I suppose. Especially when you've lost it.

But when you look at Farsight's alleged math, it's just a repetition of Farsight's bare assertions, with no actual math to back it up. Farsight knows his main assertions are refuted by the standard literature. He has no answer to those refutations. He apparently does not even understand those refutations. Nevertheless, he demands that we believe him instead of Einstein or Lemaître or Hawking or Misner/Thorne/Wheeler or Wald, apparently because he is John Duffield and lives in Poole, England:

I've told you umpteen times already. KS coordinates do a hop skippety jump over the end of time. They employ a stopped observer to fool you into thinking a stopped clock carries on merrily tick-tocking away in cloud-cuckoo land.

...snip...

Don't believe everything in your good book, RC.

Although Farsight's argument is based upon denial of Einstein's equivalence principle, he believes he is the only one here who has remained true to Einstein's original teachings:

Yes. Those textbooks are wrong in some respects. Have a read of the Golden age of general relativity and note the "paradigm shifts". I'm shifting them back to Einstein's original. Hacking through the thicket to the sleeping beauty and all that.

I tend to post here to correct some of the pseudoscience bandied about. There's a degree of "Emperors New Clothes" to it, wherein there's no supporting evidence, and if anybody probes deeper they essentially get told you don't understand the maths dear boy.

This isn't my model, it's Einstein's....

Again, it isn't my model. What we have here is patent scientific evidence along with the Einstein quotes. You dismiss it all. I've previously explained the signficance of the Schwarzschild "coordinate singularity" and why it cannot be transformed away, but this has been similarly dismissed. Asking for mathematical details of "my model" is not relevant, it's a deliberate distraction.

And Clinger, who has totally evaded the scientific evidence and everything Einstein ever said, who has absolutely no counterargument and who hides behind maths, still thinks that in a gravitational field, space is falling inwards. Like the black hole is some cosmic vacuum cleaner that sucks in space. Groan.

When Farsight says I have "totally evaded...everything Einstein ever said", Farsight means he's going to continue to ignore everything Einstein said about coordinate transformations. He seems to think he can make my quotations of Einstein go away by saying I'm the one who's ignoring Einstein.

When Farsight says I have "absolutely no counterargument", Farsight means he has absolutely no answer to the mathematical and scientific arguments I've made. It's the same with sol invictus, or Ziggurat, or ben m, or DeiRenDopa, or ctamblyn, or Vorpal. Farsight thinks their arguments will go away when he says they have no argument.

After all, "ton of bricks" Farsight is John Duffield of Poole. He's "like a cage-fighter working out toddlers", because he judges his own fights:

That's a wrap guys. You won't address the evidence, you have no counterargument, and you have no integrity. I win by a knockout. What do you want to talk about next?

 

[Reality Check]

LOL.
...usual Farsight rant snipped...
That's a wrap guys. You won't address the evidence, you have no counterargument, and you have no integrity. I win by a knockout. What do you want to talk about next?

That is a wrap, Farsight.
You ignore the science and remain obsessed with some old quotes by Einstein.
You continue to display ignorance about GR.
You won't address or even present the evidence for your theory.
You cannot even state your theory and so there is nothing to counter and so you have no integrity.
Science wins by a knockout.

 

[Ziggurat]

And still nobody will address the hard scientific evidence of the Shapiro delay and light clocks losing synchronisation at different elevations:

|------------------|
|------------------|

What's to address? That matches exactly with standard predictions of modern textbook general relativity, as taught. The conflict you imagine is entirely that: imagined.

Nobody will concede that this demonstrates with crystal clarity that the speed of light is not constant.

In the reference frame you have chosen where both clocks are stationary, this is quite true. And it agrees with standard GR. Hell, it agrees with the calculations of GR done in Kruskal coordinates too.

And you'd rather believe the sky's falling in rather than the evidence that proves that the original frozen star black hole interpetation is correct.

You keep using that word. I do not think it means what you think it means.

First off, scientific theories can never be proven correct, they can only be proven accurate. Secondly, this interpretation (meaning it doesn't even rise to the level of scientific theory) gives exactly the same testable predictions as modern general relativity. Logically, then, there is no reason to prefer you interpretation over the standard interpretation, at least not on the basis of any evidence you have presented, since it all agrees with the standard theory. Third, you're the one balking at the advancement of science, not us. If Einstein said it once, for you it becomes immutable truth. Not even Einstein had such faith in his own words. Except your faith is selective. When Einstein says that any reference frame is valid, you ignore him, and accuse me of idiocy when I agree.

 

[Brian-M]

Yes it does. But we can't say what the frequency of that radiation is before we've defined the second.

You still haven't given any logical reason why not. Once again, your argument amounts to nothing more than asserting "You just can't".

If we can:

1. Arbitrarily define the second as having a specific duration
2. Use this to calculate the frequency of a reference signal​

Why not:

1. Arbitrarily define a reference signal as having a specific frequency
2. Use this to calculate the duration of the second.​

What possible difference does it make? In both cases we end up with our newly defined second and the frequency of the reference signal in cycles per new second.

Exactly. When we have said that S=XY, then we can say 1/Y=X/S. But not before.

I was hoping that putting it this way would make it obvious to you why your objection is nonsensical. Saying S=XY is exactly the same thing as saying 1/Y=X/S.

Why do you believe that we can't simply begin by saying 1/Y=X/S, or simply f=X/S (given that f=1/y)?

No. It ticks slower.

First you claim that it's gravitational potential, not gravitational force, which determines the rate at which the clocks tick.

Then I give you a situation where the potential is the same, but the force is different, and then you claim that the clocks wouldn't tick at the same rate.

Yet you still think the rate is determined by potential, not force. Don't you see how that's inconsistent?

Although, at the risk of completely undermining my point, I'm not sure that an object located in a hypothetical cavity at the exact gravitational center of the earth would have a gravitational potential of zero. If it's knocked slightly out of position, it would "fall" towards the nearest wall of the cavity.

So it'd have a potential closer to zero than an object on the surface, but further from zero than an object infinitely distant (which would have a potential of exactly zero).

But even by that logic, if potential is what's important and an infinitely distant clock (having a potential of zero) ticks faster than a clock on the surface of the earth, then logically a clock at the center of the earth should tick faster than an identical clock on the surface of the earth (but not as fast as the infinitely distant one). Is that what you believe would happen?

No. Generally speaking, potential is "more fundamental" than force, which is the result of a non-uniform potential.

Generally speaking, force is "more fundamental" than potential, which is the result of force combined with distance.

(Just paraphrasing you to emphasize my point. I'm not sure that it's possible for either to be "more fundamental" than the other, or even that the phrase "more fundamental" has any logical meaning.)

it isn't false, but the spaceship scenario isn't exactly the same as a real gravitational field. There's a slight difference in the way the force of gravity diminishes with altitude, it's 1/r rather than 1/r², but it isn't much of an issue.

With the "gravity" produced by accelerating a spacecraft, r is effectively infinity. It doesn't diminish with distance.

But clearly you're thinking of a rotating space-station, where acceleration would be proportional to 1/r. That's okay by me, for the thought experiment we can assume that we're in a rotating ringworld type environment, only the ring is the size of a galaxy and the experienced "gravity" is completely caused by rotation. As long as the gradient of acceleration is small enough not to make a difference, we can continue.

Now compare that to living on the outside of a Dyson sphere built around a black hole with the mass of several gravities.

Inhabitants of both the ring and the sphere measure acceleration as exactly 1g. But you're locked in very well equipped laboratory the size of a football stadium, with no knowledge of whether you're on the sphere or on the ring.

The difference in acceleration between the floor and ceiling is too small for any practical experiment to measure, as is the angle at which an object falls in a vacuum. (In a small sized rotating ring, objects would appear to fall at an angle opposite to the direction of rotation, but the bigger the ring the smaller the angle, and this ring is the size of a galaxy.)

Is there any experiment you could do to distinguish between gravitation the gravitational force you'd experience on the outside of a Dyson sphere around a black hole from non-gravitational acceleration (whether on a space-ship or a galaxy sized rotating ring)?

They're all experiencing the same acceleration, so would the light clock on the surface of the Dyson sphere tick at exactly the same rate as the light clocks on the ring and spaceship?

The light clock on the ring is moving very fast (at constant speed), but has very little gravitational potential (there's nothing in the universe except the ring), the clock on the spaceship is moving faster all the time, while the light clock on the Dyson sphere has a very large gravitational potential, but isn't moving.

If anybody is still reading Dopa's posts, my advice is: don't. He hasn't conducted the gedankenexperiment using clocks calibrated against a distant pulsar, and he's ended up trying to tell you the equivalent of a train is running at two speeds at the same time. It's nonsense sophistry. Don't fall for it. Take note though of anybody who doesn't point it.

A train might be running at only one speed, but what that speed is will be determined entirely by the frame of reference of the observer. If you have a million observers, each moving at a different velocity or experiencing a different rate of acceleration, you'll get a million different answers to the question of how fast the train is moving. And every single answer would be correct... from that observer's frame of reference.

What?? I've told you literally five times now precisely what it represents - flat, empty, spacetime. Is this some sort of cognitive dissonance so extreme you can't read what I'm writing?

I could be wrong, but I think what he actually wants to know is what r, r₀ and dr represent, not what the entire formula represents, but doesn't realize that you're not interpreting his question the way he intended it to be interpreted, and so it never occurs to him to phrase it more clearly.

That's the only sane explanation I can think of, since everything else about the formula you gave was identical to the one he gave.

 

[edd]

Bah. That's a wrap guys. You won't address the evidence, you have no counterargument, and you have no integrity. I win by a knockout. What do you want to talk about next?

I was going to jokingly compare you to a certain fictional character here, but then I realised he at least admitted to a flesh wound and then called it a draw.

 

[ctamblyn]

(...rantsnip...)

We've got ct wilfully ignoring the scientific evidence and Einstein and trying to play the "your theory" card.

(...rantsnip...)

All I am asking for is emprical evidence that favours FGR over "MTW" GR. Any progress on that? Because so far, the stuff you have cited has been entirely consistent with "MTW" GR.

 

[ctamblyn]

I was going to jokingly compare you to a certain fictional character here, but then I realised he at least admitted to a flesh wound and then called it a draw.

Indeed.

 

[DeiRenDopa]

So, another question, specifically for those do have a better grasp of physics than I do: am I out of my depth, as Farsight claims?

I don't think so. In truth, I don't know if your understanding of GR is better or worse than mine, so take that for what it's worth. But I know that Sol's understanding is better than mine, I suspect WD's may be as well, and I know that Farsight's is worse than all of ours.

Thanks Zig.

It may well be that Farsight honestly, genuinely believes that I am "out of [my] depth on the physics, [and that my] gedankenexperiment is an abject failure", but it seems highly likely that his belief is not well founded, and may perhaps be quite unreasonable.

In fact, any time a poster has to start resorting to "math isn't real", well, that's pretty much a guarantee that the poster is a crank. We see it time and time again, and it usually arises from people who can't even do the math. It's also not what real scientists say when debating a theory. They'll say that the math is wrong (if it is) or the theory is wrong. Or they might say that the theory is untested under some conditions, and its accuracy under those conditions is unknown. That's even defensible in regards to black holes: we haven't actually seen any up close, so we haven't actually tested GR under such strong fields.

But "math isn't real"? That's an argument for losers.

That does seem to be a remarkably effective method of distinguishing between a crank-based approach and a science-based one.

I think it goes even deeper; I think the sorts of approaches we've seen from Farsight and MM go beyond mere stubbornness and ignorance (even if the ignorance is willful).

I think these sorts of approaches have a lot in common with those of creationists.

On the surface there are similarities such as proclaiming the inerrancy of certain documents or texts (the cherry-picked words of Einstein, from the first decade or two of the 20th century, for Farsight, for example), but the deeper similarity (or similarities) concerns the almost total inability of proponents (of crackpot ideas) to enter into meaningful discussions with critics of those ideas.

You, a critic, point to a (possible) inconsistency? The crackpot idea proponent doesn't respond, or changes the subject, or repeats word-for-word what's he's already said, or ... anything except try to engage you in a substantive discussion.

You, a skeptic, ask an excellent question, based on a serious attempt to understand the idea, as presented? The crackpot idea proponent doesn't respond, or changes the subject, or repeats word-for-word what's he's already said, or ... anything except try to actually answer the question.

You, an interested bystander, ask for clarifications concerning definitions, points of commonality with textbook physics, etc? The crackpot idea proponent doesn't respond, or changes the subject, or repeats word-for-word what's he's already said, or ... anything except try to provide any clarity.

And so on.

So what the MMs and Farsights are doing is not engaging in a science-based discussion, with the aim of deeper understanding, refining an idea, devising tests, etc (even allowing that your idea of science and theirs is not quite the same); rather, their participation is a form or marketing, or of satisfying a narcissistic tendency, or of 'spreading the Word', or ...

(By the way, W.D.Clinger has presented - in this very thread - a devastating exposé of the 'math-free' nature of Farsight's actual posts, cf his often vehement protestations to the contrary)

In the end, though, I'm left with this question: why the apparent, deep, attachment to sterility?

I mean, if what really motivates you is a desire to go to the lab to do some experiments, or head to a telescope to make some observations, or to glom onto a fascinating problem*, ... whatever it is, the MMs and Farsights leave you utterly frustrated! There is nothing, absolutely nothing, for your inquiring mind get engaged in!!

* or whatever it is that truly motivates most mathematicians (sorry, I am not close enough to your passion to do justice to it)