Black holes

[sol invictus]

I'm off to paint the laundry room.

Try not to paint yourself into a corner.

 

[DeiRenDopa]

Here is the next post containing the Farsight signature diagram; the 13th in this thread:

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:

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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.

I ended my last post with this: "... and backed it all up with some simple calculations."

Remember that Farsight's many-year attempt to communicate his ideas has failed, spectacularly, in the sense that no one (it seems) even understands what one of those ideas is (the one this signature diagram he has used to try to explain), let alone is convinced of its validity.

This particular diagram is quite different from the others posted to this point; while the two strings of (displayed) minus signs still differ by just one, the bottom string now contains just two (vs ~11-14 in earlier posts). What is Farsight trying to convey, with this dramatic change? Is it important, or was he just in a hurry (or lazy)?

By this point in the thread, Farsight certainly knows he's, once again, failing to communicate ... so it would have been better to not introduce possible confusion by such a dramatic, unexplained change.

Worse, however, is the simple appeal to naive intuition ("If [the two light beams were moving at the same speed], the two clocks would remain synchronised, contrary to Einstein's GR prediction which has been verified repeatedly").

Many readers will have heard, or read, that clock synchronization is not a trivial, intuitively obvious thing in SR, let alone in GR. To communicate his idea better, Farsight should have spent the extra few minutes at least alluding to this, but preferably describing the process clearly and succinctly.

Better yet, start with an account of clock synchronization, and apply it to synchronizing a pair of parallel-light clocks. Why better? Well, at least it avoids the strong smell of circular logic in this particular Farsight presentation, and lays out (or should lay out) the steps in the logic chain clearly.

But what about my "... and backed it all up with some simple calculations"? Well, according to the source Farsight cites, in his 7th post containing his signature diagram, "The two logic clocks exhibit virtually identical “tick” rates—differences don't show up until measurements are extended to 17 decimal places"! If you "think for yourself", as Farsight urges, it is immediately obvious that his diagram is grotesquely inaccurate (e.g. there would need to be ~10^16 minus signs - "units" - for the difference to amount to 1 unit; if each "tick" or unit were the size of an atom, ~0.1 nm say, the light beams would each need to be ~1,000 km in length), and how this pair of parallel-mirror light clocks gets to be unsynchronized becomes far from intuitively obvious, or easy to grasp.

In his next post using his signature diagram, Farsight simply adds to the confusion and lack of clarity:

Wow guys, I've just read through to the end of the thread and frankly I'm amazed. You're showing the most awful groupthink here. You still can't see the obvious. Let's try it another way. Let's say we've got two trains on parallel tracks. They start off at the same time, and one reaches the end before the other. Like this:

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Which train is going faster? Easy. The top one.

Now repeat this with two light beams in parallel-mirror clocks:

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Which one's going faster?

It's that simple, it really is.

(bold added)

Not only does he reinforce all the lack of clarity in his "racehorse" analogy, by using "two trains on parallel tracks", but he omits any mention of synchronization, and makes an even bolder appeal to your naive intuition. That's a definite no-no in Communications 101 (i.e. if you are clearly failing to get your message understood, you do NOT simply repeat it).

However, here Farsight himself becomes an impediment to communication.

There are some people who do well, in terms of learning, by being challenged so bluntly, even insulted (see the first lot of bolding); most people, however, are turned off. If your aim is to get others to understand, and accept, your idea, and if you already know it's going to be a hard slog, then you should try - very hard - to find a way to establish a firm, common basis from which to start; you should ensure that your audience is, indeed, 'with you', before moving on to the next step.

Ironically, Farsight received a pretty clear suggestion very similar to this, much earlier in the thread, from Hellbound:

To Farsight:

Don't take this the wrong way, but the boring part is your repeated assertions without anything additional in the way of evidence or even explanation. You seem to take any request for aditional information as some sort of insult or as set up for a trap. People here are trying to udnerstand what you're saying, but you haven't really made it clear at all. You keep saying the same things repeatedly without ever clarifying questions. I believe it would improve all sides of the coversation if you could slow down, put aside the animosity for a bit, and try to answer the questions...nto with generalities but with specifics. Science isn't a shotgun, it's a sniper rifle. Precision counts.

In my next post I'll illustrate how Farsight continued to be his 'own worst enemy', in terms of communication.

 

[DeiRenDopa]

Here are the 15th and 22nd posts in this thread in which Farsight uses his signature diagram:

And at the event horizon c is zero! Hence the gravitational time dilation goes infinite at the event horizon. Take the lower clock down to the event horizon, and this is what you've got:

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And that reflects what we can see with our parallel-mirror light clocks losing synchronisation at different elevations, just like those super-accurate optical clocks.

You can conduct the experiment when you and your two-parallel-mirror light clocks are in free fall. At all times the lower clock is below the upper clock, so you continue to see that the light beam in the lower clock goes slower than the light beam in the upper clock:

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(bold added)

Whatever understanding any reader who had been still trying to follow Farsight had at this point, it would surely be blown away!

By relying so heavily on naive intuition, and by simply repeating the same diagram over and over (without changing the narrative accompanying it in any significant way), Farsight has set almost everyone up for an epic failure of communication (two such failures, actually).

Most readers of this thread will have heard of, or read about, black hole event horizons; many will have also read that if you fall into a black hole (a sufficiently massive one, so you don't get spaghettified) you don't notice anything special, locally, as you pass through the event horizon. Imagine the shock, then, to read "at the event horizon c is zero!" After trying, and failing, to understand Farsight, this is a claim too far; the way this message is received - at this point in the thread - is almost certainly, universally, "the guy's nuts". If you are trying to communicate, you definitely DON'T want your audience to lose confidence in you!

How to avoid such a highly undesirable fate? Well, I'm pretty sure most of you, readers, could suggest better ways for Farsight to have worded this post.

Farsight's communication failure is surely complete by the 22nd post, where he springs "are in free fall" on his unsuspecting readers. If only he had made it clear that every previous post in which he used his signature diagram he meant the two parallel-mirror light clocks were NOT in free fall*; if only he'd taken the time to explain how being in free fall differed from being stuck on the ground (or on a bench in a lab); if only he had ...

Instead, he left all his readers - especially those who think for themselves - open to the thought that perhaps they'd misunderstood his previous posts; perhaps Farsight had meant that all the parallel-mirror light clocks (and trains, and racehorses) were in free fall, or perhaps only some (but which ones?), or ...

Quick conclusion: if Farsight's use of his signature diagram is at all typical of how he has explained his left-field ideas, in this forum and elsewhere, it's clear that some pretty basic - but entirely avoidable - communications failures may be an important reason for his half-decade failure to get others to even understand his ideas, let alone accept their validity.

Comments, anyone?

* hard to do, of course, in the 15th post; a reader who thought for herself may well have realized that Farsight was being quite inconsistent in that post

 

[Brian-M]

They don't, they airbrush over the way the speed of light varies with gravitational potential. You don't need to be a distant observer to see this, you can do it within the confines of a room.

"Distant" in this context doesn't refer to large distance, but different reference frames (which would almost always require some distance). A "distant" observer in this context would include an observer at a different velocity or rate of acceleration to that which is being observed, regardless of how far away they are.

If the two light-clocks are at different gravities they are experiencing different acceleration.

They are "distant" despite being only a few feet apart (a few feet distant). And if you are at the same "gravitational potential" as one of the clocks, this would make you a distant observer to the other.

What you can't see is time. Don't allow something you can't see to blind you to something you can.

I can't see air. But I can see a feather fall slower than a rock. So if I'm not going to allow something I can't see to "blind" me to something I can, I must conclude that the rate at which objects fall is proportional to mass. That a 10 pound bowling ball will fall at half the rate of a 20 pound bowling ball.

Which is nonsense (despite people actually believing it at one time).

I can't see air, but I can observe and measure the effects of air.
I can't see time, but I can observe and measure the effects of time.

(To be pedantic, lighter objects actually do fall slower than heavier objects, even in a vacuum. But the difference is normally too small to measure.)

In exactly what way does if fail to match the observed behavior of the universe? Where's the flaw?

In whether the mathematics provides a real solution. There's nothing wrong with the mathematics that tells you that the square root of 16 is either 4 or -4. But if you then assert that a carpet measuring -4m by -4m is something real, you've got a problem.

Okaaaaay....

So you implicitly agree that the commonly accepted math describes the observed behavior of the universe perfectly, but your objection is based on the fact that it's incompatible with your personal opinion as to the underlying behavior of the universe.

So instead you want us to different concepts of the way the universe behaves than those underlying the usual math. These concepts would produce the exact same observations to the usual math... however you can't provide us with any math that shows these concepts would produce the same observations?

(Plus you seem to have completely ignored the deconstruction of your carpet example by other posters.)

I can. I can see that optical clocks lose synchronisation when separated by only a foot of vertical distance. From that I know that parallel-mirror light clocks will do the same. So I know that this is what's happening:

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These clocks are distant to each-other (displaced by a foot in a varying gravitational field, causing them to experience different acceleration). And light can appear to travel at different speeds to a distant observer.

That's perfectly consistent with standard physics.

All you know is that the two beams of light have not traveled the same distance, but you don't know why. You can only conjecture, conclude and assume the possible reasons for the difference.

Distance = Velocity * Time

You're insisting that it must be a difference in velocity. We're saying that it could just as easily be a difference in elapsed time.

If the difference in acceleration is causing the clocks to become displaced in time, then the lower clock is lagging because the light has had less time to cover the same distance.

You've yet to provide any coherent argument for why this difference could not be caused by a variance in time. You just keep repeating "you can't see time" as if this banality were somehow significant.

There's no appears about it. One light beam is going faster than the other and that's that.

Simply insisting that something is so isn't enough to convince us. You also need to provide us with a rational reason for believing it.

Why must it be a result of variation in velocity rather than a variation in time?

For some things yes, but when we start talking about time travel and black holes you start to see differences.

We've never seen time travel or the event horizon of a black hole. How can we see differences in something we haven't seen?

But I've said that it's indistinguishable from what we regard as time traveling slower, so exactly how would your concept of light traveling slower be observably different from our concept of time traveling slower in these circumstances?

I can see light moving. I can't see time passing.

Distance = Velocity * Time
Velocity = Distance / Time

If you can perceive light moving, you're also perceiving time elapsing. Light cannot move without time elapsing.

I've shown you the maths of the Lorentz interval and how SR time dilation is based on the motion of light and Pythagoras' theorem. The interval is invariant for the twins with their parallel-mirror light clocks because their two light paths are the same length. And the empirical evidence does not support the time passes slower description.

It's only the same length in 3D Newtonian space. Different lengths in 4D relativistic space-time.

(And what empirical evidence do you have that does not support the time passes slower description?)

I've told you why. The vacuum impedance of space Z0 = √(μ0/ε0) is increasing, and c = √(1/ε0μ0).

You've been questioned about this before and completely failed to provide any coherent explanation.

From your previous "explanations" the only reason that the vacuum impedance changes is because the value of C has changed. Which leaves us with C changes because Z has changed because C has changed.

This does not explain why C (or Z) has changed.

ETA: You did also claim that Z changes because of gravitational potential, but this is no different than claiming C changes because of gravitational potential. No mechanism for this is described.

Why? The horses are side by side. Racetracks are flat. Just accept what you see. One horse lags behind the other. So the other horse is going faster.

You could make up anything to try to explain away the obvious. Don't.

It's two horses on a level track!

I'm beginning to suspect that you don't really "get" analogies. Something about the concept seems to elude you.

I'm not talking about real racetracks here. I'm talking about an imaginary racetrack symbolizing spacetime.

On this imaginary racetrack, one lane is flat and the other one curves up and down, meaning the the horse on this track has a much larger distance to cover.

But since we can't perceive the dimension in which the track curves on our TV screen, it appears as if the horse on this track is moving slower than the horse on the other track, even though they're really going the same speed.

This extra dimension we can't see on the TV screen symbolizes the extra (time) dimension we can't see in 3D space.

 

[Brian-M]

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I was sick of seeing that tired old uninteresting diagram since long before DeiRenDopa started reposting it. To liven things up a little, I've made an animated GIF version that comes with an explanation...

I hope you appreciate it Farsight. Just right click on it and select "Save Image As" to save it to your computer. Then you can upload it to your own JREF photo album like I did and link to it in your posts like I did here. Or stick it on a web-page. Or add it to posts as an attachment. Whatever you want.

ETA: I thought you might like to know that the reason for the background gradient is to represent close proximity to a black hole by means of darker shades.

 

[Brian-M]

Looking at the animation again, I suddenly realize that it looks a game of pong.

 

[Brian-M]

Farsight, I was looking through Six not-so-easy Pieces by Richard Feynman, and I found something in the article on Special Relativity that has me wondering how your "speed of light changes" theory would apply.

(This is dealing with constant velocity rather than the gravity/acceleration that's been argued about in this thread, but seems to touch on many of the same ideas that have been brought up, which I thought was interesting.)

I'd like your thoughts about it. Here's the relevant text, typed in exactly as it is in the book...

This slowing of the clocks in a moving system is a very peculiar phenomenon, and is worth an explanation. In order to understand this, we have to watch the machinery of the clock and see what happens when it is moving. Since that is rather difficult, we shall take a very simple kind of clock. The one we choose is rather a silly kind of clock, but it will work in principle: it is a rod (meter stick) with a mirror at each end, and when we start a light signal between the mirrors, the light keeps going up and down, making a click every time it comes down, like a standard clicking clock. We build two such clocks, with exactly the same length, and light always travels with speed c. We give one of these clocks to the man to take along in his space ship, and he mounts the rod perpendicular to the motion of the ship; then the length of the rod will not change. How do we know that perpendicular lengths do not change? The men can agree to make marks on each other's y-meter stick as they pass each-other. By symmetry, the two marks must come at the same y- and y'-coordinates, since otherwise, when they get together to compare results, one mark will be above or below the other, and so we could tell who was really moving.

Now let us see what happens to the moving clock. Before the man took it aboard, he agreed that it was a nice, standard clock, and when he goes along in the space ship he will not see anything peculiar. If he did, he would know he was moving—if anything at all changed because of the motion he could tell he was moving. But the principle of relativity says this is impossible in a uniformly moving system, so nothing has changed. On the other hand, when the external observer looks at the clock going by, he sees that the light, in going from mirror to mirror, is "really" taking a zig-zag path, since the rod is moving all the while. We have already analyzed such a zig-zag motion in connection with the Michelson-Morley experiment. If in a given time the rod moves forward a distance proportional to u in Figure 3-3, the distance the light travels in the same time is proportional to c, and the vertical distance is proportional to √(c² - u²).

That is, it takes a longer time for light to go from end to end in the moving clock than the stationary clock. Therefore the apparent time between the clicks is longer for the moving clock, in the same proportion as shown in the hypotenuse of the triangle (that is the source of the square root expressions in our equations). From the figure it is also apparent that the greater u is, the more slowly the clock appears to run. Not only does this particular kind of clock run more slowly, but if the theory of relativity is correct, any other clock, operating on any principle whatsoever, would also appear to run slower, and in the same proportion—we can say this without further analysis. Why is this so?

To answer the above question, suppose we had two other clocks made exactly alike with wheels and gears, or perhaps based on radioactive decay, or something else. Then we adjust these clocks so they both run in precise synchronism with our first clocks. When light goes up and back in the first clocks and announces it's arrival with a click, the new models also complete some sort of cycle, which they simultaneously announce by some doubly coincident flash, or bong, or other signal. One of these clocks is taken into the space ship, along with the first kind. Perhaps this clock will not run slower, but will continue to keep the same time as it's stationary counterpart, and thus disagree with the other moving clock. Ah no, if that should happen, the man on the ship could use this mismatch between the two clocks to determine the speed of his ship, which we have been supposing is impossible. We need not know anything about the machinery of this new clock that might cause this effect—we simply know that whatever the reason, it will appear to run slow, just like the first one.

Now if all moving clocks run slower, if no way of measuring time gives anything but a slower rate, we shall just have to say, in a certain sense, that time itself appears to be slower in a space ship. All the phenomena there—the man's pulse rate, his thought processes, the time he takes to light a cigar, how long it takes to grow up and get old—all these things must be slowed down in the same proportion, because he cannot tell he is moving.

I'd like your thoughts about the speed of light on the moving space ship. Has it slowed down or not? Also, what do you think of that final paragraph?

 

[Farsight]

...Never once have you actually addressed the substance of what I've said.

That's absolutely untrue, I've addressed your posts at length and in great detail. Since you take that line I will not address your post #720. Let's call it a day Zig.

 

[grmcdorman]

I was sick of seeing that tired old uninteresting diagram since long before DeiRenDopa started reposting it. To liven things up a little, I've made an animated GIF version that comes with an explanation...

[qimg]http://www.internationalskeptics.com/forums/picture.php?albumid=721&pictureid=5752[/qimg]​

[lurker off]Cute. You've got a spelling error in the image, though: "beteen".

I've been enjoying the discussion here, although some of the explanations are over my head. Still, though, I don't understand what Farsight is getting at: how does this effect, which is completely congruent with relativity theory, disprove relativity? It seems it's central to his complaint. Why is it so important?

[/lurker on]

 

[DeiRenDopa]

I was sick of seeing that tired old uninteresting diagram since long before DeiRenDopa started reposting it.

Well, for what it's worth, I was pretty sick of seeing it used, over and over again, too.

To liven things up a little, I've made an animated GIF version that comes with an explanation...

[qimg]http://www.internationalskeptics.com/forums/picture.php?albumid=721&pictureid=5752[/qimg]​

I hope you appreciate it Farsight. Just right click on it and select "Save Image As" to save it to your computer. Then you can upload it to your own JREF photo album like I did and link to it in your posts like I did here. Or stick it on a web-page. Or add it to posts as an attachment. Whatever you want.

ETA: I thought you might like to know that the reason for the background gradient is to represent close proximity to a black hole by means of darker shades.

That's pretty cool, thanks!

But are you sure that's what Farsight intended? In every instance where he posted his signature diagram?

Oh, and perhaps the caption could do with some editing? Locally, "time passes " (or however you want to say it) just the same as it always has, had, and does; the relative 'speed' of the clocks is a non-local phenomenon ...

 

[DeiRenDopa]

That's absolutely untrue, I've addressed your posts at length and in great detail. Since you take that line I will not address your post #720. Let's call it a day Zig.

So, once again, you have failed, Farsight, to communicate your ideas.

Like, what?, every other time in the last five+ years?

Farsight, if you and Ziggurat were exchanging emails, and no one else ever got to read them, your stance would make sense. However, you chose to respond to Ziggurat's posts (and he to yours) here, on an internet forum. Where there are many readers.

If you are not interested in trying to explain your ideas to others, so that they at least understand them*, why waste your time by posting here in the first place?

And if you are interested in trying to explain your ideas to others, so that they at least understand them, why don't you at least reflect on why you have been, apparently, so spectacularly unsuccessful at doing so? For many years??

* accepting their validity is a different matter

 

[Farsight]

"Distant" in this context doesn't refer to large distance, but different reference frames (which would almost always require some distance). A "distant" observer in this context would include an observer at a different velocity or rate of acceleration to that which is being observed, regardless of how far away they are.

What different reference frames? It's just two beams of light moving through space. It's misty or smoky so you can see them. You can't see the reference frames. They're just abstract things that you derive using the motion of light.

They are "distant" despite being only a few feet apart (a few feet distant). And if you are at the same "gravitational potential" as one of the clocks, this would make you a distant observer to the other.

It doesn't matter where I am, the lower beam gets to the end faster than the upper beam.

I can't see air. But I can see a feather fall slower than a rock. So if I'm not going to allow something I can't see to "blind" me to something I can, I must conclude that the rate at which objects fall is proportional to mass. That a 10 pound bowling ball will fall at half the rate of a 20 pound bowling ball.

Don't clutch at straws. You know what air is. You breath it. You can feel it when the wind blows on your face. On a hot day it shimmers.

I can't see air, but I can observe and measure the effects of air.
I can't see time, but I can observe and measure the effects of time.

But what you can see is one light beam moving faster than the other. Don't kid yourself that it isn't because of something you can't see.

So you implicitly agree that the commonly accepted math describes the observed behavior of the universe perfectly, but your objection is based on the fact that it's incompatible with your personal opinion as to the underlying behavior of the universe.

Flip that around. The maths describes the observed behaviour, but that's incompatible with what people say it describes. You see light moving slower, not time passing slower.

So instead you want us to different concepts of the way the universe behaves than those underlying the usual math.

No, I want you to correct your concept to match what you can see.

These concepts would produce the exact same observations to the usual math... however you can't provide us with any math that shows these concepts would produce the same observations?

I told you about the invariant interval and how it employs Pythagoras' theorem. That's simple enough. The maths is the same maths. I can't give you any new maths. All I can do is point to the evidence and tell you to look at what you see and try to give you a better understanding of what the terms actually represent.

(Plus you seem to have completely ignored the deconstruction of your carpet example by other posters.)

My negative carpet example was good. Zig was being dishonest when he tried to conflate distance with displacement. I have only so much patience for that kind of thing.

These clocks are distant to each-other (displaced by a foot in a varying gravitational field, causing them to experience different acceleration). And light can appear to travel at different speeds to a distant observer.

It doesn't appear to travel at a different speed. It travels at a different speed. The gedanken scenario is where you replace the light beams with trains. When one train hits the buffer the other train explodes. All observers see the lower train explode.

All you know is that the two beams of light have not traveled the same distance, but you don't know why. You can only conjecture, conclude and assume the possible reasons for the difference.

I know that they have because I used the motion of light to define the metre, and that doesn't change. The bigger second and the slower light cancel each other out.

You're insisting that it must be a difference in velocity. We're saying that it could just as easily be a difference in elapsed time.

But I'm with Einstein on this.

If the difference in acceleration is causing the clocks to become displaced in time, then the lower clock is lagging because the light has had less time to cover the same distance.

There is no such thing as "displaced in time". You have no freedom of motion in the time "dimension". It isn't the same kind of dimension as the spatial dimensions. And clocks don't clock up the flow of time. They clock up some kind of regular cyclic motion. That's all they do. That's what they all do.

You've yet to provide any coherent argument for why this difference could not be caused by a variance in time. You just keep repeating "you can't see time" as if this banality were somehow significant.

On the contrary. I've told you what clocks do, I've explained the definition of the second and the metre, I've told you what Einstien said, I've pointed you at the Godel/Einstein book, I've told you about the Shapiro delay, and I've shown you one light beam moving faster than another. The boot is on the other foot Brian. You continue to insist that the light beams are travelling at the same speed and that "time is flowing" slower where the lower beam is. And yet there is no time flowing between those mirrors. It's just light moving.

Simply insisting that something is so isn't enough to convince us. You also need to provide us with a rational reason for believing it.

I have done. Now trust the evidence of your own eyes and look. Do you see time flowing? No. What you see is light moving.

Why must it be a result of variation in velocity rather than a variation in time?

Because you need motion to have time. Not the other way around. You must have seen some science-fiction movie where somebody "stops time". What actually stops is motion. When you freeze the frame or stop the clock you stop motion not time.

We've never seen time travel or the event horizon of a black hole. How can we see differences in something we haven't seen?

The differences are in your understanding, and we do physics to understand the universe. It matters.

But I've said that it's indistinguishable from what we regard as time traveling slower, so exactly how would your concept of light traveling slower be observably different from our concept of time traveling slower in these circumstances?

You can observe the light travelling slower. You can't observe time travelling slower.

Distance = Velocity * Time
Velocity = Distance / Time

Best to say speed because velocity is a vector quantity comprised of speed and direction, but nevermind.

If you can perceive light moving, you're also perceiving time elapsing. Light cannot move without time elapsing.

You're seeing light moving. You aren't actually seeing time elapsing. That's just what you call it.

It's only the same length in 3D Newtonian space. Different lengths in 4D relativistic space-time.

No, the light-path lengths have the same length in flat 3D Newtonian space. That's why the interval is invariant.

(And what empirical evidence doyou have that does not support the time passes slower description?)

The evidence I can see. You don't have any evidence for time passes slower. Again, I can show you light moving, you can't show me time passing.

You've been questioned about this before and completely failed to provide any coherent explanation.

It's coherent. A concentration of energy (usually in the form of matter such as a star) "conditions" the surrounding space. That's what Einstein said.

From your previous "explanations" the only reason that the vacuum impedance changes is because the value of C has changed. Which leaves us with C changes because Z has changed because C has changed.

It isn't like that. The concentration of energy imparts a gradient in Z within the surrounding space, and as a result of that you also have a gradient in c.

This does not explain why C (or Z) has changed.
ETA: You did also claim that Z changes because of gravitational potential, but this is no different than claiming C changes because of gravitational potential. No mechanism for this is described.

I have to get into electromagnetism and describe the photon to explain that. And even then all I can really say is that this is how photons are.

I'm beginning to suspect that you don't really "get" analogies. Something about the concept seems to elude you.

Not so. I use them a lot. But I use the right analogies.

I'm not talking about real racetracks here. I'm talking about an imaginary racetrack symbolizing spacetime.

You can't move through spacetime. No kidding. You can move through space and plot a worldline in spacetime, but you can't move through spacetime.

On this imaginary racetrack, one lane is flat and the other one curves up and down, meaning the the horse on this track has a much larger distance to cover.

It doesn't. See what I said about the metre.

But since we can't perceive the dimension in which the track curves on our TV screen, it appears as if the horse on this track is moving slower than the horse on the other track, even though they're really going the same speed.

Don't try to explain away what you can see with something you can't.

I've got to go I'm afraid. But yes I like your GIF. Just look at it. Take the evidence at face value. Which light pulse is moving faster?

 

[edd]

It really does matter where the 'distant observer' is, Farsight. The information about the clock ticking has to leave the clock and reach that location, and that's where the difference lies. Those of us who agree with the textbooks think an infalling object passes through the horizon in finite proper time, but the time for photons from that object to escape diverges. You think that the infalling object freezes because the photons from that object take longer to escape.

It's not just about what the clock is doing - what the signal from the clock is doing and how long it takes to get to the observer is crucial to the whole discussion and glossing over this is a very dangerous thing to do.

 

[DeiRenDopa]

Using the 'parallel-mirror light clock as a game of pong' illustration in Brian-M's post, it may be possible to show more clearly that Farsight's claim of a variable speed of light is somewhat more radical than he has stated.

Use the upper ("low gravity") clock to time the packets of light (may we call them photons? ) in the lower ("high gravity") one. Apply Farsight's method for calculating the speed of light, c, in the lower clock. c, as measured this way, will be different than c, calculated by someone co-located with the lower clock (details later).

Now image another pair of games of pong parallel-mirror light clocks, located above the upper one; call these the "lower gravity" (the bottom one of the new pair) and the "even lower gravity" clocks (the top one).

Again apply Farsight's method for calculating the speed of light, c, in the original, lower clock (the "high gravity" one), only this time use as our standard clock the "lower gravity" one. c, as measured this way, will be different than c, calculated by someone co-located with the "high gravity" clock.

And it will also be different from the value for c calculated using the "low gravity" clock!

That's three different values for c.

Now repeat, using as our standard clock the "even lower gravity" one. Once again, a different c. We're up to four now.

Now image another pair of games of pong parallel-mirror light clocks, located ...

Conclusion: using the Farsight method, the speed of light at any location can have many different values, simultaneously. It all depends on which clock you choose as your standard ...

 

[Ziggurat]

My negative carpet example was good. Zig was being dishonest when he tried to conflate distance with displacement. I have only so much patience for that kind of thing.

I didn't conflate distance and displacement, you did. You said it was a square carpet. But how can you know it's square unless you also know the direction of each length? How can you know anything at all about its shape, or its area, with only a length? Obviously, you cannot. You need a displacement, or you won't get a square. Never once have you tried to explain how you can get a square without a displacement. That's the real dishonesty here: your refusal to actually engage in debate.

But that prospect was pretty obviously doomed once you started claiming "math isn't real". That's the sine qua non of the physics crank.

 

[anglolawyer]

Excuse me for butting in but I have a question. Sorry if it's a stupid one. Say you are observer A. At 10 o'clock and at 2 o'clock, some distance away, are B and C. They are travelling away from each other at 51% of the speed of light each. Cumulatively 102% of the speed of light. I have two questions about this:

1 from A's vantage point, how does this differ from B being stationary and C travelling at 102% of the speed of light (which I understand is not allowed)? and
2 from B's vantage point, is C a black hole and vice versa (regardless of mass)?

Sorry, three questions)

3 is there a better thread than this one for dumb questions about physics?

 

[DeiRenDopa]

These clocks are distant to each-other (displaced by a foot in a varying gravitational field, causing them to experience different acceleration). And light can appear to travel at different speeds to a distant observer.

It doesn't appear to travel at a different speed. It travels at a different speed. The gedanken scenario is where you replace the light beams with trains. When one train hits the buffer the other train explodes. All observers see the lower train explode.

Somewhat like this, right ("*" means the train explodes)?

|-*-*-*-*-*-*-*-*-*-*-*-*-|
|-*-*-*-*-*-*-*-*-*-*-*-*-|

But what if this happens?

|-*-*-*-*-*-*-*-*-*-*-*-*-|
|-*-*-*-*-*-*-*-*-*-*-*-*-|

How could that possibly happen?!?

Well, the train had two bombs on it, one tied to the buffer of the upper track (the one you were watching); the other tied to the buffer of a different track, one that you weren't aware of. Sorta like this:

|-*-*-*-*-*-*-*-*-*-*-*-*-|
|-*-*-*-*-*-*-*-*-*-*-*-*-|
|-*-*-*-*-*-*-*-*-*-*-*-*-|

So the speed of the doomed train depends on which buffer contains the trigger.

Or, saying this another way, the Farsight speed of light depends upon which distant clock you use; if you have a million distant clocks, the Farsight speed of light could have up to a million different values ...

 

[sol invictus]

Excuse me for butting in but I have a question. Sorry if it's a stupid one. Say you are observer A. At 10 o'clock and at 2 o'clock, some distance away, are B and C. They are travelling away from each other at 51% of the speed of light each. Cumulatively 102% of the speed of light. I have two questions about this:

1 from A's vantage point, how does this differ from B being stationary and C travelling at 102% of the speed of light (which I understand is not allowed)? and

Regarding A and B: in the latter scenario, light signals bounced back and forth between A and B will arrive at regular intervals. In the former, they will take longer and longer to complete a round-trip, and they will be Doppler (red) shifted.

Regarding A and C: In the latter scenario, light signals sent by A will reach C and can be sent back to A, although with significant Doppler shift. Therefore C cannot be moving at 1.02c. In fact, no matter how much C (or A) accelerates, light signals can always be exchanged between them.

2 from B's vantage point, is C a black hole and vice versa (regardless of mass)?

No.

However, if B and C were to collide at very high velocity, they might form a black hole.

3 is there a better thread than this one for dumb questions about physics?

Not at all - this is supposed to be about black holes (rather than crackpot physics), and your questions have significantly raised its level.

 

[anglolawyer]

sol-invictus

Thank you. I may have more stupid questions anon.

 

[catsmate]

Two years ago? That's nothing, Farsight's view hasn't changed since at least 2008.

The funny thing about 2008? It's about 4 years ago. An 18-year-old high school graduate could have entered college in 2008, learned vector calculus, learned mechanics, learned differential equations, learned special relativity, learned differential geometry, learned general relativity, and (preparing to graduate in a few months) actually become a physicist. (And, simultaneously: learned a language, learned critical theory, played Ultimate, worked nights and weekends, took summers off, etc..)

Not to forget; found out they didn't understand the universe/world/women, fell in love, built a siege catapult, read books, fell out of love, built a laser¹, made friends they'd still know twenty years later, organise a conference, read more books, make DDT, participate in a riot, found the love of their life..........




¹ Not related to the previous item. At all.