The Speed of Light is Not Constant

[Farsight]

That's contrary to general relativity, Farsight, because an essential feature of GR is that gravity is space-time curvature.

Spacetime curvature isn't spatial curvature and/or temporal curvature. There's no spatial curvature at all. The temporal curvature is merely a curvature in your plot of optical clock readings. See what I said above about what clocks do. The temporal curvature is merely a curvature in your plot of the speed of light in inhomogeneous space.

It doesn't, except indirectly through gravity.

It does. See The Role of Potentials in Electromagnetism by Percy Hammond and look at the sentence near the end-note: “We conclude that the field describes the curvature that characterizes the electromagnetic interaction".

Farsight, I'm not going on a wild link chase. You must tell us what electromagnetic geometry is, and work it out mathematically. If you don't, you will make baby Maxwell cry, and baby Einstein and baby Minkowski and baby Feynman also.

What you mean is that you will emotionally dismiss anything that challenges what you think you know, even Einstein and the evidence.

Hmmn. I see przyk and rpenner have given up on their "non local" petard. And no comments about redshift and blueshift wherein conservation of energy applies. Maybe one or two people have learned a thing or two.

 

[Farsight]

So, now Baez has it wrong?

It's more like Baez has an omission. See what I said to lpetrich above about Percy Hammond and electromagnetic curvature.

There's no mention by baez there of your ''space waves''.

I know. But take a look at displacement current where Maxwell said light consists of transverse undulations in the same medium that is the cause of electric and magnetic phenomena.

Farsight, if you want to know what Baez means by space alone being curved, can I suggest the book 'Exploring Black Holes'.

It's by Taylor and Wheeler. It's wrong. See this online intro. it says Albert Einstein told us that a star or other massive object distorts spacetime in its vicinity. He didn't. Einstein told us that the star conditions the surrounding space, rendering it inhomogeneous. Taylor and Wheeler are responsible for a great deal of confusion.

I don't need to read your second link to that... 'An Alternative Interpretation of Curved Spacetime.' Where are you going??

I'm telling you that it's space around the Earth not spacetime, and it's inhomogeneous, not curved. See Einstein's 1920 Leyden Address and pay careful attention to this:

"According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that "empty space" in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμv), has, I think, finally disposed of the view that space is physically empty."

You may also want to have a look at this essay by Pete Brown: http://arxiv.org/abs/physics/0204044

"The interpretation of gravity as a curvature in space-time is an interpretation Einstein did not agree with. "

See the OP, you will find Einstein saying light curves because the speed of light varies with position. But nowhere will you find him saying light curves because spacetime is curved. That something that confuses cause and effect. A concentration of energy alters the surrounding space. As a result it's inhomogeneous. If you plot this inhomogeneity you will find that your plot is curved. And because this inhomogeneity is there, the motion of light is curved and matter falls down. We model all this using curved spacetime. But spacetime is an abstract mathematical model, it isn't what space is. Only Wheeler thought that matter tells space how to curve. It's a totally schoolboy misunderstanding, it's been taught for decades, but it's wrong.

 

[Farsight]

Now I understand what some of the fuss here is all about.

Allow me to point out that if there were events or even galaxies receding from us at velocities > c, something inevitable happens to that observation besides "the red shift becomes infinite". When frequency shifts to ZERO cycles per second...

Sorry dan, that just isn't true. Check out the ant on the rubber rope.

Electrons, you see, get their inertial masses from the Higgs mechanism. Please stop thinking like it's still the 20th century. The discovery of the Higgs boson was something that changes science and enhances our understanding of relativity because it explains why nothing made of energy or matter can ever exceed c in a vacuum. When anyone says that something exceeds the speed of light, like that 2003 paper, for instance, well, if you really can't tell the difference between real astrophysics and someone like this, or the Bogdan brothers, you probably deserved the delusion.

http://arxiv.org/abs/astro-ph/0310808 is real astrophysics. And the Higgs boson gets its mass from the kinetic energy of the LHC protons. Because the mass of a body is a measure of its energy-content.

 

[danshawen]

Sorry dan, that just isn't true. Check out the ant on the rubber rope.

http://arxiv.org/abs/astro-ph/0310808 is real astrophysics. And the Higgs boson gets its mass from the kinetic energy of the LHC protons. Because the mass of a body is a measure of its energy-content.

Why in the name of all that is cosmological would anyone worry about whether something as distant as 2 X the end of the observable universe ever gets to where we are in the first place?

It's like looking for the lowest and most massive turtle (Russell's heckler's turtles) on the stack, isn't it? Hypothetically, when that information arrived (and not red-shifted to oblivion) it would tell you information about another universe so distant that no event in it could affect ours, unless you are buying into the Perimeter Institute's latest journey of imagination, that is. Why not be content to observe whatever you can observe, and only explain that? This is how string theory went wrong on the other end of scales, isn't it?

True, the Higgs briefly gets its own mass from the QUARKS in the LHC protons, and then decays, and then trillions more Higgs bosons come out of the vacuum and exchange energy from a seemingly inexhaustible field of them. But electrons get their smaller masses, theoretically at least, from the same mechanism, even if those are not part of what is accelerated in that particular collider. You actually have a good point there. We'll need a much higher energy electron collider design before we can see something like that. There's a lot of work to do observing real, actual stuff that has nothing to do with whether or not God's underpants or socks got lost in some cosmic dryer. My suggestion is, we stop paying for idle speculation, whether it has supporting fictional math to go with it or not.

The speed of light is the constant that assures that atomic matter exists and keeps its structure, that energy propagates, accelerates and is able to behave the way it does, instead of just dissipating into empty space until it reaches another one of those other universes I could care less about. All of this works as well for matter standing still relative to us as it does for a pair of proton pancakes counterrotating in the LHC. Until we knock the Higgs out of them, that is.

 

[PhysBang]

Just about all clocks go slower when they're lower. The exception is the grandfather clock, where the clock rate depends on the local slope of potential rather than the potential itself.

Can you show us the equations that govern a grandfather clock that show that it does not go slower?

No lpetrich, that's being empirical. Now go and read Time travel is science fiction to understand this point. A clock doesn't literally measure the flow of time like some cosmic gas meter. There is no time flowing through it. Instead a clock "clocks up" some kind of regular cyclical motion and shows you some kind of cumulative display that you call the time. So when a clock goes slower, it's because that regular cyclical motion is going slower. Even when it's an optical clock.

Can you please show us how to describe a physical system without using time?

Because it would take me a long time and distract us from the point of discussion.

Right. Another excuse to hide your inability to do physics. If your points are important, then you should be able to support them. So let's see some physics.

You've missed the squared off the s,

The square is not required.

and it isn't a distance, it's an interval which is said to be zero for a photon.

It's a distance by the definition of distance in geometry and topology. Again you show that you do not understand the basic mathematics of the field in which you claim to be an expert.

It's Lorentz invariant because time is just a measure of motion, and if you're the twin on the out-and-back trip, the light-path length in your parallel-mirror light-clock is the same as mine.

That's an interesting claim. Now can you do the mathematics to do what lpetrich has asked or will you continue to dodge the question?

No. Energy and momentum are merely two aspects of energy-momentum. One is a time-based measure, the other is a distance-based measure, and the divide by c to convert from one to the other. Think about a cannonball in space coming at you at 10m/s. You catch it to slow it down. The energy measure relates to the stopping distance, the momentum measure relates to the stopping time. And you can't reduce the energy without reducing the momentum.

That's some interesting dogma you have there. Can you show us how to describe a physical system using this dogma? Otherwise, we'll keep using a physics that works.

I don't know. Dividing by τ doesn't make much sense.

At last some truth!

It's all easy stuff lpetrich, especially when you understand why the maths applies.

But you have just demonstrated that you do not know. You have just shown that not only can't you do the math, you can't understand the basics!

Because I'm with Einstein, and you're the one trying to dismiss him. You're on the wrong side of the crackpot fence, not me.

You are the person denying that Einstein was correct to claim that the speed of light is invariant for infinitesimal regions. You also deny all of Einstein's cosmological models. How do you pick and choose from Einstein if not from your dogma?

It's more like Baez has an omission. See what I said to lpetrich above about Percy Hammond and electromagnetic curvature.

You have said nothing about electromagnetic curvature other than to show that you dogmatically believe in it. Please show us how you would describe a physical system using electromagnetic curvature. You are the expert, aren't you?

I know. But take a look at displacement current where Maxwell said light consists of transverse undulations in the same medium that is the cause of electric and magnetic phenomena.

While it might be interesting, it seems at odd with Einstein's claims. Can you show us a physical description where one uses this medium?

It's by Taylor and Wheeler. It's wrong. See this online intro. it says Albert Einstein told us that a star or other massive object distorts spacetime in its vicinity. He didn't. Einstein told us that the star conditions the surrounding space, rendering it inhomogeneous. Taylor and Wheeler are responsible for a great deal of confusion.

Can you show us a single example of where inhomogeneous space can be used to describe the fall of an object? Even a reference where a falling object is described with inhomogeneous space.

It's a totally schoolboy misunderstanding, it's been taught for decades, but it's wrong.

So show us how to do physics the Farsight way. For at least ten years you have said people were wrong but you have shown no replacement physics.

 

[lpetrich]

Just about all clocks go slower when they're lower. The exception is the grandfather clock, where the clock rate depends on the local slope of potential rather than the potential itself.

Whatever is supposed to make a difference for a grandfather clock.

A clock doesn't literally measure the flow of time like some cosmic gas meter. There is no time flowing through it.

What illiterate childish nonsense. It suggests a VERY limited imagination, and it seems like literal-mindedness that would embarrass a fundie. Yes, embarrass a fundie.

A clock's action is a *function* of time.

(Me about the math of special relativity: Why don't you demonstrate it to us?)

Because it would take me a long time and distract us from the point of discussion.

Irrelevant. It's a way of showing that you have a professional-level understanding of special relativity, as opposed to the appearance of understanding from scriptural exegesis. Don't you want to demonstrate to everybody that you can go head-to-head with Einstein himself in math???

(Minkowskian distance invariant)

You've missed the squared off the s, and it isn't a distance, it's an interval which is said to be zero for a photon. It's Lorentz invariant because time is just a measure of motion, and if you're the twin on the out-and-back trip, the light-path length in your parallel-mirror light-clock is the same as mine.

Fail. You failed to use math. Instead you used word-drool. If you had used math, you might even have been able to show why the Lorentz boost has the form that it does.

(Lorentz boosts as hyperbolic rotations by analytic continuation...)

No. It's because the angle of the light in your parallel-mirror light-clock reduces from 90 degrees towards 0 degrees as you go faster.

Fail again. You failed to use math. Use it instead of word-drool.

(Energy from momentum...)

No. Energy and momentum are merely two aspects of energy-momentum. One is a time-based measure, the other is a distance-based measure, and the divide by c to convert from one to the other. Think about a cannonball in space coming at you at 10m/s. You catch it to slow it down. The energy measure relates to the stopping distance, the momentum measure relates to the stopping time. And you can't reduce the energy without reducing the momentum.

Fail again. More word-drool instead of math.

(Lorentz-boost (τ,0,0,0), then divide by τ and multiply by mass, and then compare to momemtum and energy...)

I don't know. Dividing by τ doesn't make much sense.

Fail yet again. But thank you, Farsight, for showing some humility for once.

It's all easy stuff lpetrich, especially when you understand why the maths applies.

Then you should have done the math. Instead, you spouted yet more of your usual word-drool.

(Martin Gardner's criteria...)

Talk physics, lpetrich. Your repeated references to your crackpot bible does you no credit. Because I'm with Einstein, and you're the one trying to dismiss him. You're on the wrong side of the crackpot fence, not me.

As Martin Gardner noted about inverted theories,

Mathematicians prove the angle cannot be trisected. So the crank trisects it. A perpetual motion machine cannot be built. He builds one. There are many eccentric theories in which the "pull" of gravity is replaced by a "push." Germs do not cause disease, some modern cranks insist. Disease produces the germs. Glasses do not help the eyes, said Dr. Bates. They make them worse. In our next chapter we shall learn how Cyrus Teed literally turned the entire cosmos inside-out, compressing it within the confines of a hollow earth, inhabited only on the inside.

 

[danshawen]

With apologies to Martin Gardiner, whose writings I usually agree with:

Angles cannot be trisected WITH ONLY A COMPASS AND A STRAIGHT EDGE, because these tools are not capable of cubic operations (necessary to trisect), only quadratic ones. They can be trisected using another tool such as a Tomahawk trisector, which is neither a compass nor a straight edge, nor can a TH trisector be produced using only these tools. However, I have seen teenage cranks (and stupidity culls these nicely, the way nature intended) demonstrating trisection with the wrong tools. I was never one of those, but forums like this one tend to attract them.

Perpetual motion machines cannot be built according to conservation of energy and the laws of thermodynamics. But because E=mc^2, who really cares? Free energy rains down on us from a nuclear furnace, and that's just one place to get almost free energy without a lot of tinkering and expecting to get something for nothing.

Disease may not produce germs, but cures like antibiotics sometimes change harmful germs into even more virulent ones. Evolution just works, sometimes with a vengeance.

The wrong prescription glasses can make your eyesight much worse in a hurry, and not just when you are wearing them. I have personal experience to back that one up, unfortunately.

I don't see Farsight as a crank, with or without my improved prescription eyeglasses; far from it. But thanks for quoting Martin Gardiner. That's one of his many books I haven't read, but I will.

 

[lpetrich]

Spacetime curvature isn't spatial curvature and/or temporal curvature. There's no spatial curvature at all. The temporal curvature is merely a curvature in your plot of optical clock readings. See what I said above about what clocks do. The temporal curvature is merely a curvature in your plot of the speed of light in inhomogeneous space.

Empty word-drool.

It does. See The Role of Potentials in Electromagnetism by Percy Hammond and look at the sentence near the end-note: “We conclude that the field describes the curvature that characterizes the electromagnetic interaction".

I read it, and it's a curvature in an abstract mathematical sort of sense, not a curvature of space-time. So your scriptural exegesis fails.

Here's how it works.

If you wish to define a gradient in a space (like space-time) with a metric, you add a term that depends on the metric, the "connection coefficients", to improve is transformation properties:

(metric-covariant derivative) = (ordinary partial derivative) + (connection coefficients)

Electromagnetism and other elementary-particle gauge theories work in much the same way:

(gauge-covariant derivative) = (ordinary partial derivative) + (charge * potential)

If one goes around in a small loop, one finds (commutator of different directions of covariant derivative) . (loop area with directions)

Commutator: (apply second direction, then apply first direction) - (apply first direction, then apply second direction)

In a space with a metric, one gets the Riemann curvature tensor, while in a gauge theory, one gets (charge * field).

I note in passing that metric-covariant and gauge-covariant derivatives are not mutually exclusive, that it's possible for a covariant derivative to have both metric and gauge correction terms.

(Me: "Farsight, I'm not going on a wild link chase. You must tell us what electromagnetic geometry is, and work it out mathematically. If you don't, you will make baby Maxwell cry, and baby Einstein and baby Minkowski and baby Feynman also.")

What you mean is that you will emotionally dismiss anything that challenges what you think you know, even Einstein and the evidence.

Einstein??? That's a scriptural percussionist's argument.

But take a look at displacement current where Maxwell said light consists of transverse undulations in the same medium that is the cause of electric and magnetic phenomena.

Scriptural percussion again. Present-day physicists are not bound by anything that Maxwell or Einstein or whoever had said. Farsight, you seem to have a very theology-like view of science where theories are revealed truths, never to be challenged.

But Maxwell didn't get his equations by climbing Ben Nevis, Einstein didn't get relativity by climbing Mount Blanc or the Matterhorn. Minkowski didn't get space-time unification by climbing some hill on the Baltic-Sea coast, and Feynman didn't get quantum electrodynamics by climbing Mount Whitney.

It's by Taylor and Wheeler. It's wrong. See this online intro. it says Albert Einstein told us that a star or other massive object distorts spacetime in its vicinity.

So Taylor and Wheeler are heretics?

He didn't. Einstein told us that the star conditions the surrounding space, rendering it inhomogeneous. Taylor and Wheeler are responsible for a great deal of confusion.

I'm sure that Einstein would have agreed with Taylor and Wheeler. Farsight, that's the problem with your scriptural-exegesis method. It fails to capture important details of theories. You seize on some quotes and make very far-reaching interpretations of them, interpretations often not justified by the quotes themselves.

(some theologian-like Einstein-thumping snipped)

 

[nimbus]

Einstein's 1920 Leyden Address.

"According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that "empty space" in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gµv), has, I think, finally disposed of the view that space is physically empty."

My bold

Farsight, do you understand what’s that telling us?
It’s telling us, that the spatial geometrical properties far away from mass are flat throughout or homogeneous throughout or Euclidean.

As against, the altered geometrical properties of space near a massive object. In other words, near mass, space is not homogeneous throughout in its geometrical properties.

Nowhere have I seen in a GR textbook, and that includes two of Einstein’s own, reference to this ‘electromagnetic waves and space waves’ as the conditioner of space and that includes...
Einstein's 1920 Leyden Address.

conditioned by the matter

I read that as old fashioned talk for mass/energy alters space.The ‘’electromagnetic waves and space waves’’ are your personal add-on.
As I said before... if you want to know what Baez meant by curved space alone, then see 'Exploring Black Holes'.

 

[przyk]

Only we define the metre as the length of the path travelled by light in vacuum during a time interval of 1/299,792,458th of a second. And it isn't approximate.

Yes, at least in inertial conditions. And? Like you say, that's a definition, not a measurement.

And nor is something 1m away remote, just as something 30cm isn't remote.

Whatever you want to call it, the ambiguity in defining quantities a finite distance away that the physics FAQ was talking about still applies for a distance of 30cm in GR.

You are reduced to saying local means a region of zero extent. No region. It's absurd.

No, the limit of zero distance, or "infinitesimal" distance, if you prefer. That's not the same thing and there's nothing absurd about it.

That's not the issue. The issue is a curvature of rays of light can only occur when the speed of light varies with position.

I already understand GR too well to be able to learn anything useful from simplified slogans like this.

That's not dismissing Einstein, by the way. Einstein had a lot more to say about how GR is structured and what depends on what, including the trajectories of light rays. That's why he published a research paper explaining the theory. Even as condensed as it is (he wrote it as a physicist for a target audience of other physicists, assuming all the prior education that that should imply), it's over 50 pages long and most of that is just laying out the foundations. Summarising GR in a few canned slogans just doesn't work and isn't useful to anybody.

What you're saying is nothing is local. So the local speed of light is meaningless.

No, that's not what I'm saying. Limits and infinitesimals? Most interactions in modern theories in physics are formulated this way, including GR. I wouldn't call that "nothing".

 

[Farsight]

Farsight, do you understand what’s that telling us?

Yes, it's quite clear. Where a gravitational field is, space isn't homogeneous, and it isn't isotropic.

It’s telling us, that the spatial geometrical properties far away from mass are flat throughout or homogeneous throughout or Euclidean. As against, the altered geometrical properties of space near a massive object. In other words, near mass, space is not homogeneous throughout in its geometrical properties.

He isn't telling us that. He doesn't use the word geometrical.

Nowhere have I seen in a GR textbook, and that includes two of Einstein’s own, reference to this ‘electromagnetic waves and space waves’ as the conditioner of space and that includes... Einstein's 1920 Leyden Address. [conditioned by the matter]. I read that as old fashioned talk for mass/energy alters space. The ‘’electromagnetic waves and space waves’’ are your personal add-on.

See the Doc30 Foundation of the General Theory of Relativity and look at page 185 where Einstein says "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". It’s energy that causes gravity, not matter per se. Yes, Einstein said matter in his Leyden Address, but he identified electromagnetism with matter elsewhere* and Maxwell did talk of transverse undulations. My "add-on" isn't something I've dreamt up.

As I said before... if you want to know what Baez meant by curved space alone, then see 'Exploring Black Holes'.

Nimbus, appreciate this: Taylor and Wheeler got some things wrong. That's essentially what this thread is all about.

* I couldn't find it, I'll have a dig around.

 

[Farsight]

Empty word-drool...

You're dismissing Einstein with epithets. It's no substitute for physics.

True, the Higgs briefly gets its own mass from the QUARKS in the LHC protons

No it doesn't. Dan, if you want to talk about the Higgs particle or mechanism or field, please start a new thread. Meanwhile have a read of Matt Strassler's article.

You are the person denying that Einstein was correct to claim that the speed of light

I'm the person saying Einstein said the speed of light varies with position. You're the person saying the speed of light is only constant in an infinitesimal region. And not much else.

Yes, at least in inertial conditions. And? Like you say, that's a definition, not a measurement...

Whatever you want to call it, the ambiguity in defining quantities a finite distance away that the physics FAQ was talking about still applies for a distance of 30cm in GR...

No, the limit of zero distance, or "infinitesimal" distance, if you prefer. That's not the same thing and there's nothing absurd about it...

No, that's not what I'm saying. Limits and infinitesimals? Most interactions in modern theories in physics are formulated this way, including GR. I wouldn't call that "nothing"...

It's absurd to claim the speed of light is constant but only in an infinitesimal region. End of story.

I already understand GR too well to be able to learn anything useful from simplified slogans like this.

No, you don't understand it. You've never read the original material by Einstein. If you had you would have spotted the differences between current GR teaching and what Einstein actually said.

That's not dismissing Einstein, by the way. Einstein had a lot more to say about how GR is structured and what depends on what, including the trajectories of light rays. That's why he published a research paper explaining the theory. Even as condensed as it is (he wrote it as a physicist for a target audience of other physicists, assuming all the prior education that that should imply), it's over 50 pages long and most of that is just laying out the foundations. Summarising GR in a few canned slogans just doesn't work and isn't useful to anybody.

You absolutely are dismissing Einstein. Einstein said light curves because the speed of light varies with position. Nowhere did he say light curves because spacetime is curved. He didn't confuse space with spacetime like Taylor and Wheeler.

Now again, look at the gif. Yes the mirrors could be shown tilted back a little and the light could be arcing a little. But tidal force is not detectable so it's the same tilt and arc, so it doesn't matter. Is there any time flowing between those parallel-mirrors? No. Are they measuring the flow of time? No. But like the NIST optical clocks, the lower clock goes slower. OK, is the light going slower when it's lower? Here's the deal przyk: you would have to be crazy to say no.

It isn't only Einstein on my side, it's Koks at Baez, and Magueijo and Moffat, and PhysBang (even though he now won't admit it), and the evidence you can see with your own eyes. Right in front of your face. In the room you're in, 30cm apart. It isn't remote at all, there's no escaping it, and I'm not some "my theory" guy. I'm just the guy who told you something that corrected what you were taught. Who told you about something you were taught wrong. And when you finally appreciate that you were taught wrong, remember this: you heard it here first.

 

[paddoboy]

And when you finally appreciate that you were taught wrong, remember this: you heard it here first.

In actual fact, it is you who are wrong.
For all intents and purposes, the speed of light is constant.
The next fact you need to learn, is that in a gravitational field [curved spacetime] light obviously has slightly further to travel.
And the third fact you should be aware of, is that light is not seen to stop at a BH's EH, in any FoR.
External frames sees the light red shifted further and further to infinity, but never stopping and never crossing the EH.....From a local FoR, of someone falling into the BH, everything within that frame proceeds as per normal...he crosses the EH, and finds himself on a one way trip in a finite amount of time to the Singularity.

If you see things any differently, then you need to supply evidence of those views, and get them properly peer reviewed.

 

[PhysBang]

My "add-on" isn't something I've dreamt up.

And yet you cannot point to a single place in any scientific use of GR where your "add-on" shows up. That should demonstrate to you, as it does to everyone else, that you did dream it up.

Nimbus, appreciate this: Taylor and Wheeler got some things wrong. That's essentially what this thread is all about.

And yet you are unable to point to what they got wrong, how what they said conflicts with observations, or how anything you dreamt up matches observations.

I'm the person saying Einstein said the speed of light varies with position. You're the person saying the speed of light is only constant in an infinitesimal region. And not much else.

Einstein clearly used a constant speed of light in infinitesimal regions. Just look at the equations you post when you cut and paste from his work.

And besides noting things Einstein wrote, I also ask you to show us how your physics works. So far, you seem completely unable to do any physics.

It's absurd to claim the speed of light is constant but only in an infinitesimal region. End of story.

If you can show us how your physics does better than Einstein's, please do so.

No, you don't understand it. You've never read the original material by Einstein. If you had you would have spotted the differences between current GR teaching and what Einstein actually said.

You haven't yet demonstrated a significant difference. I actually have read much of original Einstein, including things where he got things grossly wrong. In the end, if it's going to be physics it has to match up with observations. Contemporary GR does it, but not contemporary Farsight-Relativity. So far, you have failed to show any difference between how someone should describe a physical system and how it is done. Despite the fact that you regularly malign scientists for doing things incorrectly.

You absolutely are dismissing Einstein. Einstein said light curves because the speed of light varies with position.

No, that is a fantasy that you cling to. You have twisted his words; even you should know that he said things in a different word order than that and with different logical implications.

Nowhere did he say light curves because spacetime is curved.

Except in all of his equations. You know, the real physics that is tested.

If you want to defend this fantasy Einstein of yours, you need to test your physics. However, we know that you can't do physics.

Now again, look at the gif.

That might fool the weak-minded, but we will need you to show us the relevant equations. You need to show why that gif is relevant and how it might match a real scenario.

It isn't only Einstein on my side, it's Koks at Baez, and Magueijo and Moffat, and PhysBang (even though he now won't admit it),

See, there is you lying again. I find it quite pleasing for the person who I call a liar to so clearly lie.

and the evidence you can see with your own eyes. Right in front of your face. In the room you're in, 30cm apart. It isn't remote at all, there's no escaping it, and I'm not some "my theory" guy. I'm just the guy who told you something that corrected what you were taught. Who told you about something you were taught wrong. And when you finally appreciate that you were taught wrong, remember this: you heard it here first.

If you can show us how your physics works, then we'll believe it. Until then, you are just a sad man so trapped in his fantasy that he will lie in order to protect it.

 

[przyk]

You've never read the original material by Einstein.

Nope. I've read Einstein's 1916 research paper. As far as I am concerned, in every important respect it's the same theory of gravity I learned in university. You can't keep using that escape.

Now again, look at the gif.

You're mistaking your gif for the territory.

It isn't only Einstein on my side, it's Koks at Baez, and Magueijo and Moffat, and PhysBang

One of those people is here to speak for himself and he vehemently disagrees with you.

 

[lpetrich]

Yes, it's quite clear. Where a gravitational field is, space isn't homogeneous, and it isn't isotropic.

I want to see the math behind that assertion. Yes, the math. The sort of math that Einstein had done.

See the Doc30 Foundation of the General Theory of Relativity and look at page 185 where Einstein says "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy".

Argument by scriptural exegesis, sacred-book interpretation. Farsight, when I read your posts, I sometimes get the impression that I'm reading theology.

I'm not saying that I consider Einstein wrong about gravitational self-energy having the same gravity as other sorts of mass/energy. I'm pointing out that it's the wrong sort of argument.

Nimbus, appreciate this: Taylor and Wheeler got some things wrong.

Another theologian-like argument. That Taylor and Wheeler were heretics who had strayed from Einstein's revealed truth.

I'm the person saying Einstein said the speed of light varies with position.

Treating Einstein's words as revealed truth. A theologian's sort of argument.

It's absurd to claim the speed of light is constant but only in an infinitesimal region. End of story.

Not at all. It's a limiting case. Farsight, you ought to learn some calculus some time.

You've never read the original material by Einstein.

Have you ever tried to understand his math and work it out for yourself?

If you had you would have spotted the differences between current GR teaching and what Einstein actually said.

Implying that Einstein's statements are revealed truth and that present-day GR theorists have gone astray. So like a theologian.

You absolutely are dismissing Einstein.

So Farsight's interpretations are Einstein's revealed truth. More theologian-like argument.

And when you finally appreciate that you were taught wrong, remember this: you heard it here first.

Martin Gardner crackpot criterion #1: "He considers himself a genius"

 

[lpetrich]

With apologies to Martin Gardiner, whose writings I usually agree with:

Angles cannot be trisected WITH ONLY A COMPASS AND A STRAIGHT EDGE, because these tools are not capable of cubic operations (necessary to trisect), only quadratic ones. They can be trisected using another tool such as a Tomahawk trisector, which is neither a compass nor a straight edge, nor can a TH trisector be produced using only these tools. However, I have seen teenage cranks (and stupidity culls these nicely, the way nature intended) demonstrating trisection with the wrong tools. I was never one of those, but forums like this one tend to attract them.

About that one, some mathematicians in antiquity were able to trisect angles with an extra tool: the neusis. It is a marked ruler that can slide past a point and pivot around it. However, the neusis seemed like an inelegant add-on to some other mathematicians back then.

 

[Farsight]

Nope. I've read Einstein's 1916 research paper. As far as I am concerned, in every important respect it's the same theory of gravity I learned in university.

No it isn't. Show me where Einstein says light curves because spacetime is curved. Whilst the The Foundation of the Generalised Theory of Relativity doesn't include anything with the outright clarity of the OP quotes, Einstein does say "we see immediately that the principle of the constancy of light-velocity must be modified". The context suggests he's talking about vector-quantity velocity, but the other quotes and "the principle" should tell you he meant speed.

One of those people is here to speak for himself and he vehemently disagrees with you.

He can disagree all he likes, but he got caught out. Because he said this:

"In a sense, this was done in 1905, when Einstein developed special relativity. This constancy of the speed of light is a postulate of the theory, so it is "shown" through the effectiveness and practicality of the theory. The same is true for general relativity, developed in 1915, which holds that the speed of light is constant at any infinitesimal region of a coordinate system".

The speed of light is only constant in an infinitesimal region. A region of zero extent. Not the room you're in. So "a curvature of rays of light can only occur when the speed of light varies with position".

See, there is you lying again. I find it quite pleasing for the person who I call a liar to so clearly lie.

See above. That's what you said. I'm not the liar here. Now am I?

I want to see the math behind that assertion. Yes, the math. The sort of math that Einstein had done.

There isn't any math behind it. It's an Einstein quote from his Leyden Address: "This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that “empty space” in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν), has, I think, finally disposed of the view that space is physically empty." You should also know this from the Baez website. Space isn't curved where a gravitational field is. So what is it? It's inhomogeneous.

Argument by scriptural exegesis, sacred-book interpretation.

lpetrich, if you're going to dismiss not only what I say, but what Einstein said, and the hard scientific evidence, there really isn't much point in me talking to you any more. I mean, look at your post. It's all dismissal and denial. Not physics. You're the one clinging to a bible here.

 

[OnlyMe]

No it isn't. Show me where Einstein says light curves because spacetime is curved. Whilst the The Foundation of the Generalised Theory of Relativity doesn't include anything with the outright clarity of the OP quotes, Einstein does say "we see immediately that the principle of the constancy of light-velocity must be modified". The context suggests he's talking about vector-quantity velocity, but the other quotes and "the principle" should tell you he meant speed.

The above and discussion generally is confusing separate issues of interpretation. Yes, spacetime as the source of gravity is a modern conceptual interpretation. As far as I have read Einstein, he never presented GR as the mechanism of gravitation only as a description of how objects interact as a result of gravitation... The only possible justification for believing that Einstein meant speed instead of velocity, is because that supports your misinterpretation of his intent. Again, Einstein was expanding on and improving on the mechanics of Newton's earlier conclusions.., and neither Newton nor Einstein were attempting to describe the underlying mechanism... Spacetime curvature, as the cause of gravity is a modern interpretation and one of the major issues that divide GR and attempts to develop a fully function model of quantum gravity.

You continually read, almost everything you read wearing your own special pair of colored glasses, such that you see what you are looking for rather than what is right there in front of you. We all do that to some extent, but you seem to carry it to an extreme, such that you raise belief and theory to a claimed state of fact.

He can disagree all he likes, but he got caught out. Because he said this:

"In a sense, this was done in 1905, when Einstein developed special relativity. This constancy of the speed of light is a postulate of the theory, so it is "shown" through the effectiveness and practicality of the theory. The same is true for general relativity, developed in 1915, which holds that the speed of light is constant at any infinitesimal region of a coordinate system".

The speed of light is only constant in an infinitesimal region. A region of zero extent. Not the room you're in. So "a curvature of rays of light can only occur when the speed of light varies with position".

I assume here your are quoting przyk? There is nothing in the above statement that is in conflict with Einstein or any modern interpretation of GR. All that is being said is that the constancy of the speed of light is a postulate of SR that has been supported by experiment and holds true within the context of GR where SR holds true. GR did not overthrow SR or Newtonian gravity. It retains both as valid within the context of the weak field limit.., where spacetime can be treated as flat... This includes most of the volume of our solar system, where variation from Newton's predictions are so insignificant that NASA still relies largely on Newton's field equation and historical data. IOW it is easier to get to Mars and other distant locations using Newton's understanding of gravity with in flight corrections as needed than to even attempt to plot a course to the same locations using Einstein's field equations. There are just too many variables involved for the later to be practical.
========

You keep raising the issue of the NIST optical clocks and their separation... The clocks were separated by far more than 30 cm. they were in separate labs and even if they were in the same lab their size would result in a separation of more that 30 cm. The 30 cm references a difference in elevation not separation. And yes it does support the predictions of GR with respect to the operation of clocks in a gravitational field.., but it does not prove anything about the speed of light, nor does it prove anything about what is a local or remote measurement. Both clocks represent local time, as defined by their locations. There have been enough local measurements of the speed of light in vacuum, carried out in different locations and elevations within the earth's gravitational field, which agree on the speed of light, to support the SR postulate that the speed of light is universally constant, when measured in inertial frames of reference... At least to the extent that we have been able to experimentally confirm, with present technology and funding.

If you are measuring the speed of light at the floor of a lab with the accuracy of the clocks available today, the ceiling of that lab is a remote location, just as the floor would be a remote location from the ceiling under those conditions. This is true for speed of light measurements and clock rates. Reference any experiment that measures the speed of light in any two inertial locations with the same degree of accuracy, where the results do not agree on the constancy of speed of light.

 

[lpetrich]

No it isn't. Show me where Einstein says light curves because spacetime is curved. ...

As if his writings are Holy Writ.

In that 1916 paper, Einstein did not explicitly state that space-time is curved, though he did state that its geometry is non-Euclidean. He did not even state that the Riemann tensor is related to space-time curvature. But in his 1921 book The Meaning of Relativity, he called it the "Riemann curvature tensor", though he did not seem to have stated that space-time is curved. It's almost as if Einstein had originally thought of curvature as extrinsic only and not intrinsic, something that results from the embedding of a space in a higher-dimensional space. That's rather obvious for a line, whose curvature is entirely extrinsic. A line is a 1D space, but with more dimensions, a space can have intrinsic as well as extrinsic curvature. Starting with a surface, which is a 2D space.

I checked Charles Misner's, Kip Thorne's and John Archibald Wheeler's 1973 book Gravitation, Steven Weinberg's 1971 book Gravitation and Cosmology, and Wikipedia's article on general relativity, and they all state that space-time is curved.

The speed of light is only constant in an infinitesimal region. A region of zero extent. Not the room you're in. So "a curvature of rays of light can only occur when the speed of light varies with position".

That's still nonlocal. Furthermore, as I'd showed, attempting to measure the speed of light over curved space-time depends on the points that one chooses for one's measurements. I'd earlier calculated the speed discrepancy that results from space-time curvature in the small-size limit, and it's easy to correct for. Its overall size is (Riemann tensor) * (distance or time)[sup]2[/sup]. In distance units, the Riemann tensor due to gravity is (G*M)/(r[sup]3[/sup]*c[sup]2[/sup]) for a distance r away from an object with mass M. For a distance of 1 m on the Earth's surface, that makes a discrepancy of about 10[sup]-23[/sup].

(Me: where's the math?)

There isn't any math behind it. It's an Einstein quote from his Leyden Address: "This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that “empty space” in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν), has, I think, finally disposed of the view that space is physically empty."

So your argument is not based on the math of the theory, but on your interpretation of one Einstein quote.

lpetrich, if you're going to dismiss not only what I say, but what Einstein said, ...

Treating Einstein's words as revealed truth.