The Speed of Light is Not Constant

[Farsight]

Przyk, I must correct this:

The infinitesimal local gravitational field doesn't have any effect on a local measurement of the speed of light. Tangent to every point on the riemann manifold the spacetime is flat. Same as at boundary. Flat...

Spacetime is not what space is. It's an abstract thing, a mathematical model in which motion does not occur. The "Riemann manifold" is similarly abstract. Here's a depiction of it:

GNUFDL image by Johnstone, see wikipedia

It isn't flat, just as a mountain isn't flat. Yes, this "rubber-sheet" depiction isn't ideal, but it isn’t totally wrong. Imagine you’ve placed a whole lot of parallel-mirror light-clocks in an equatorial slice through the Earth and the surrounding space. When you plot all the clock rates, your plot looks like the picture above. It's from the Wikipedia Riemann curvature tensor article. And the crucial point is this: The "Riemann manifold" is curved because the speed of light is not constant. If it was constant throughout the room you're in, those NIST optical clocks would stay synchronised, and your pencil wouldn't fall down. Light wouldn't curve down either, because "a curvature of rays of light can only occur when the speed of light varies with position". Look again at Ned Wright's deflection and delay of light: "In a very real sense, the delay experienced by light passing a massive object is responsible for the deflection of the light". Light doesn't curve because spacetime is curved. Light curves because the speed of light varies with position. Spacetime is curved because the speed of light varies with position. Because a concentration of energy in the guise of a star "conditions" the surrounding space. It doesn't curve it, it renders it inhomogenous. See Baez: "Note: not the curvature of space, but of spacetime. The distinction is crucial". Space isn't curved in the room you're in, it's "neither homogeneous nor isotropic".

 

[nimbus]

Farsight, I think we all know a free falling particle describes a goedesic in spacetime.

Here's Baez explaining the distinction between space and spacetime.Your link.
Baez

Similarly, in general relativity gravity is not really a `force', but just a manifestation of the curvature of spacetime. Note: not the curvature of space, but of spacetime. The distinction is crucial. If you toss a ball, it follows a parabolic path. This is far from being a geodesic in space: space is curved by the Earth's gravitational field, but it is certainly not so curved as all that!

My bold

So, after baez has taken this trouble of explaining the difference between just space and spacetime, and that space alone can be curved by the Earth's gravitational field, where does that leave your...

Spacetime is curved because the speed of light varies with position

How come Baez has explained we can have curvature in space alone and not just in spacetime?

 

[Farsight]

Space isn't curved by the Earth's gravitational field. It's curved by an electromagnetic field variation. Think of it like this: when a seismic wave travels through the ground, the ground waves. When an ocean wave travels through the sea, the sea waves. Where an electromagnetic wave travels through space, space waves. And where it waves it curves. Have a google on electromagnetic geometry. However when you combine a whole lot of out-of-phase photons, the curvatures cancel one another out, and you're left with space that's inhomogeneous rather than curved. Then you have a gravitational field rather than an electromagnetic field. Light curves because space is inhomogeneous, and we model it as curved spacetime. See http://cpl.iphy.ac.cn/EN/Y2008/V25/I5/1571.

 

[Dr_Toad]

Insane.

 

[wellwisher]

t's not false. Conservation of energy applies. There is no magical mysterious mechanism via which a photon loses energy as it ascends, or gains energy as it descends. When you direct a 511keV photon into a black hole, the black hole mass increases by 511kev/c². Or are you saying it increases by a greater amount. Or an infinite amount?

According to GR, light will blue shift as it goes down a space-time well because space-time gets more contracted. The opposite is true of the universal red shift where the energy value of photons are decreasing as space-time expands. This is observed. The irony is dark energy which is assumed to be responsible for the expansion of the universe, causes photons to lose energy via red shift.

 

[danshawen]

According to GR, light will blue shift as it goes down a space-time well because space-time gets more contracted. The opposite is true of the universal red shift where the energy value of photons are decreasing as space-time expands. This is observed. The irony is dark energy which is assumed to be responsible for the expansion of the universe, causes photons to lose energy via red shift.

Sure, as viewed by someone already trapped in the gravity well of a BH, other luminous objects approaching the EH will appear to be blue shifted. But this is not a unique situation.

The stars in the entire Andromeda Galaxy are blue shifted from our vantage point because it is headed in the direction of our own Milky Way galaxy at a rate of several hundred km/h, including our relative velocity. It will begin to arrive (or we will) in about 4 billion years. It is true that the vast majority of the cosmos is red shifted, and that the shift is greater with increasing distance.

In addition, there are important relativistic corrections to Doppler shift data that guarantee that the expansion of the universe in all directions will not result in the geometric conclusion that mutually orthogonal expansion yields any velocities in any direction that is greater than c.

If DE is responsible for a portion of the red shifts, I can't think of any good way to separate that out of the calculations previously done for the expansion of the universe and the Hubble constant. Perhaps it is time to give up on using these methods for cosmology because of such insurmountable uncertainties.

 

[PhysBang]

Yes. The maths of special relativity in particular is pretty trivial.

That is an interesting and deceptive way to answer the question. In the past, Farsight, you admitted that you could not do the math of GR. By your answer here it seems tat you still can't do that math. This is a problem, since you are making claims about GR and you clearly can't understand it. So when you talk about optical clocks, you can't make any predictions about how much a clock will slow down, so we can't have any evidence from these clocks for Farsight Relativity.

You totally misunderstood. You have two stars close to one another. You shine a light beam through the gap between them. That light beam doesn't veer towards either star, it goes straight as an arrow.

I suppose that you can't explain this with math, you merely take this on faith.

I give the argument, supported by the references and the evidence,

You did not give us the mathematical evidence: you are making vague predictions that you cannot compare to evidence because you don't know the math.

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.

This is something that arose after and because of GR. It is something that we continue to test for its applicability.

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

By the definitions of GR, something 30cm away is remote. If you would bother to learn the math, you would know this. You should know this from reading your favorite Baez source. So if we believe that you can read, we should believe that you know differently but you say false things anyway.

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

Welcome to calculus. You will need to learn it in order to learn physics.

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. Einstein said it, Don Koks says it, Joao Magueijo and John Moffat says it, I say it, and more importantly the evidence says it. And to evade all that, you've put yourself in a reductio ad absurdum situation.

Your lie here is that you say that these people agree with you, but they do not. They all say that the speed of light varies because of changes in spacetime, whereas you claim the reverse. Until we can see your math, we have no reason to believe you.

You painted yourself into a corner and hoist yourself with your own petard, then ran away, and you refused to discuss the matter further on your own forum, deleting my posts.

You post insults to people all over the internet: these posts get removed. If you posted some math, that post would never be removed.

Space isn't curved by the Earth's gravitational field. It's curved by an electromagnetic field variation.

Please show us the math. You are making extreme, outside-of-mainstream claims. If you have evidence, then let's compare your predictions of how much electromagnetic field variation curves space with some measurements.

 

[Farsight]

According to GR, light will blue shift as it goes down a space-time well because space-time gets more contracted.

That's what people say. But the descending photon doesn't actually gain any energy. Hence if you direct a 511keV photon into a black hole its mass increases by 511keV/c², not by some other amount. Conservation of energy applies.

The opposite is true of the universal red shift where the energy value of photons are decreasing as space-time expands. This is observed. The irony is dark energy which is assumed to be responsible for the expansion of the universe, causes photons to lose energy via red shift.

Again, that's what people say. There's all sorts of issue in cosmology.

 

[Farsight]

Sure, as viewed by someone already trapped in the gravity well of a BH, other luminous objects approaching the EH will appear to be blue shifted.

They appear to be blue-shifted. Think what happens when I drop you. You start to fall at 9.8 m/s/s. Potential energy is converted into kinetic energy. And this potential energy isn't in some magical mysterious place, it's your mass-energy. When you land on the ground the kinetic energy is dissipated and your mass is now reduced. Check out the mass deficit. Because you now comprise less energy the photon appears to have gained energy. It hasn't. You lost it. The photon didn't change, you did.

But this is not a unique situation. The stars in the entire Andromeda Galaxy are blue shifted from our vantage point because it is headed in the direction of our own Milky Way galaxy at a rate of several hundred km/h...

Exactly. If you were to race towards the Andromeda Galaxy you'd see the photons as being blue-shifted. But the photons didn't change, you did.

In addition, there are important relativistic corrections to Doppler shift data that guarantee that the expansion of the universe in all directions will not result in the geometric conclusion that mutually orthogonal expansion yields any velocities in any direction that is greater than c.

Check out http://arxiv.org/abs/astro-ph/0310808 :

"We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light..."

If DE is responsible for a portion of the red shifts, I can't think of any good way to separate that out of the calculations previously done for the expansion of the universe and the Hubble constant. Perhaps it is time to give up on using these methods for cosmology because of such insurmountable uncertainties.

IMHO with a few tweaks here and there it's all pretty simple. But you have to go back to the beginning and get the relativity right.

 

[Farsight]

That is an interesting and deceptive way to answer the question. In the past, Farsight, you admitted that you could not do the math of GR.

No I haven't.

By your answer here it seems that you still can't do that math. This is a problem, since you are making claims about GR and you clearly can't understand it. So when you talk about optical clocks, you can't make any predictions about how much a clock will slow down, so we can't have any evidence from these clocks for Farsight Relativity.

We know how much a clock will slow down:

$$t_0 = t_f \sqrt{1 - \frac{2GM}{rc^2}} = t_f \sqrt{1 - \frac{r_0}{r}} $$

And we know that NIST optical clocks demonstrate a measurable slowdown when you move it 30cm lower. See this David Wineland Interview.

I suppose that you can't explain this with math, you merely take this on faith...

You did not give us the mathematical evidence...

By the definitions of GR, something 30cm away is remote. If you would bother to learn the math, you would know this...

Maths doesn't provide explanation, maths isn't evidence, and something 30cm away is not remote.

Your lie here is that you say that these people agree with you, but they do not. They all say that the speed of light varies because of changes in spacetime

No they don't. I'm not lying. But see this post where you said the speed of light is only constant if you're measuring it in a region of infinitesimal spatial extent. A region the size of a point. So it isn't constant in the room you're in, now is it?

whereas you claim the reverse. Until we can see your math, we have no reason to believe you.

You have every reason to believe me when Einstein and the evidence along with Don Koks and Jo Magueijo and John Moffat back me up.

You post insults to people all over the internet: these posts get removed. If you posted some math, that post would never be removed.

I don't post insults all over the internet, you do.

Please show us the math. You are making extreme, outside-of-mainstream claims. If you have evidence, then let's compare your predictions of how much electromagnetic field variation curves space with some measurements.

Go and look at the role of the potentials in electromagnetism by Percy Hammond. I'm not making extreme outside-of-mainstream claims. Again, go and look at electromagnetic geometry. I'm not some my-theory guy who makes things up, I just tell you about stuff you don't know about.

 

[PhysBang]

No I haven't.

You once wrote that you never got past page 30. If you can do the math of GR, then show us the math of FR. So far, when asked about where your ideas show up in GR, you have been forced to admit that they do not show up, that nobody, including Einstein, used your ideas in their calculations. If you've learned how to do the math in the last month, then show us.

We know how much a clock will slow down:

$$t_0 = t_f \sqrt{1 - \frac{2GM}{rc^2}} = t_f \sqrt{1 - \frac{r_0}{r}} $$

Show us from your principles your prediction of how much light will slow down. Do not jsut cut-and-paste from someone else's work.

Maths doesn't provide explanation,

When physics regard numerical measurement, like it does for pretty much every physics application, then the math is required to do the physics and to even make a description of a physical system.

maths isn't evidence,

Unless we retreat to your fantasy or dogma, we require a mathematical statement to compare your predictions and descriptions with observation.

and something 30cm away is not remote.

It is by definition of "remote", as discussed in the Baez article.

No they don't. I'm not lying.

You are clearly lying here, because you know that these people think that spacetime changes produce changes in the (pseudo)speed of light, not the other way around as you claim (without showing your work).

But see this post where you said the speed of light is only constant if you're measuring it in a region of infinitesimal spatial extent. A region the size of a point.

That post is you cherry-picking a quotation and telling a lie about what I wrote. Good of you to point out another lie. And good of you for pointing out your ignorance. 1) One cannot measure an infinitesimal distance. 2) The speed of light is also constant over distances in certain kinds of systems of coordinates (read the Baez article that you cite so often without reading, comprehending, or telling the truth about). 3) An infinitesimal region is not the size of a point.

So it isn't constant in the room you're in, now is it?

Of course not, since there are significant spacetime differences over the distant points of the room.

You have every reason to believe me when Einstein and the evidence along with Don Koks and Jo Magueijo and John Moffat back me up.

Except that you lie about what they say. They all say that spacetime curvature causes physical changes, you say that the changing speed of light, even at infinitesimal distances, causes physical changes. They know math, you do not.

Go and look at the role of the potentials in electromagnetism by Percy Hammond. I'm not making extreme outside-of-mainstream claims. Again, go and look at electromagnetic geometry. I'm not some my-theory guy who makes things up, I just tell you about stuff you don't know about.

This is another attempt by you to dodge the question. Let's see FR's predictions. Let's see FR's description of anything. So far, you can't even describe how a pencil falls, even though you claim that pencils fall because of the changing speed of light.

 

[brucep]

According to GR, light will blue shift as it goes down a space-time well because space-time gets more contracted. The opposite is true of the universal red shift where the energy value of photons are decreasing as space-time expands. This is observed. The irony is dark energy which is assumed to be responsible for the expansion of the universe, causes photons to lose energy via red shift.

According to your wellwisher bullshit interpretation of GR.

Gravitational redshift is frame dependent natural phenomena. So what kind of redshift will you measure when you try to measure it in a local invariant frame where the light is being emitted or just passing through? Nada because light never gets tired.

wellwisher probably interprets the gravitational redshift as tired light bullshit phenomena. IE: he probably thinks light gives up energy to the gravitational field as it follows the natural path. Idiot wind wellwisher post.

 

[krash661]

i'm just curious but,
the ones who spew against GR, realize the three eclipse involved be tween 1907 and 1917 ?

 

[brucep]

You once wrote that you never got past page 30. If you can do the math of GR, then show us the math of FR. So far, when asked about where your ideas show up in GR, you have been forced to admit that they do not show up, that nobody, including Einstein, used your ideas in their calculations. If you've learned how to do the math in the last month, then show us.


Show us from your principles your prediction of how much light will slow down. Do not jsut cut-and-paste from someone else's work.

When physics regard numerical measurement, like it does for pretty much every physics application, then the math is required to do the physics and to even make a description of a physical system.

Unless we retreat to your fantasy or dogma, we require a mathematical statement to compare your predictions and descriptions with observation.

It is by definition of "remote", as discussed in the Baez article.

You are clearly lying here, because you know that these people think that spacetime changes produce changes in the (pseudo)speed of light, not the other way around as you claim (without showing your work).

That post is you cherry-picking a quotation and telling a lie about what I wrote. Good of you to point out another lie. And good of you for pointing out your ignorance. 1) One cannot measure an infinitesimal distance. 2) The speed of light is also constant over distances in certain kinds of systems of coordinates (read the Baez article that you cite so often without reading, comprehending, or telling the truth about). 3) An infinitesimal region is not the size of a point.


Of course not, since there are significant spacetime differences over the distant points of the room.

Except that you lie about what they say. They all say that spacetime curvature causes physical changes, you say that the changing speed of light, even at infinitesimal distances, causes physical changes. They know math, you do not.

This is another attempt by you to dodge the question. Let's see FR's predictions. Let's see FR's description of anything. So far, you can't even describe how a pencil falls, even though you claim that pencils fall because of the changing speed of light.

Farsight makes so many undocumented comments about physics that its become a monumental waste of time to continue to read anything he writes down [copied and paste]. Par for this forum.

 

[lpetrich]

You compare them with the evidence. And the evidence is that an optical clock goes slower when its lower.

And a non-optical clock?

Then when you open up that clock, you see that there isn't any time flowing through it.

That's childish. Abysmally childish. Like saying that clouds and rainbows are solid objects. They look like solid objects, so does that mean that they are solid objects?

The maths of special relativity in particular is pretty trivial.

Why don't you demonstrate it to us? Do the following:

Show that the distance invariant
S = x[sup]2[/sup] + y[sup]2[/sup] + z[sup]2[/sup] - c[sup]2[/sup]*t[sup]2[/sup]
is rotation-invariant, Lorentz-invariant, and reflection-invariant in space coordinates x,y,z and time coordinate t. All you need to do for rotation and Lorentz boosts is to do them in two dimensions each: two space dimensions, and one space dimension and time.

Show why Lorentz boosts are sometimes called hyperbolic rotations. You will have to do some analytic continuation here and there, multiplying some variables by i = sqrt(-1).

Show that the relativistic momentum p and the relativistic energy E satisfy the differential relation dE = v.dp, derived from the work expression dE/dt = F.v.

Lorentz-boost the trajectory of a stationary particle: t = τ, x = y = z = 0. Divide the resulting t,x,y,z by τ. Multiply by the particle's mass. Compare the resulting expressions to the relativistic momentum and energy of that particle. What do you find?

Farsight, you must do it with mathematics only. I repeat, mathematics only. No quoting from your heroes, and no trying to make excuses for not doing it. If you are truly capable of doing professional-quality work in relativity, then you must be capable of doing all this by yourself.

(Martin Gardner's crackpottery criteria...)

Looks like I'm seeing book-thumping. Talk physics, lpetrich.

On the contrary, some of your theories satisfy #4, and your descriptions of your physics capabilities satisfy #1.

 

[nimbus]

Space isn't curved by the Earth's gravitational field.

So, now Baez has it wrong? your link...Baez

space is curved by the Earth's gravitational field, but it is certainly not so curved as all that!

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

Farsigth, if you want to know what Baez means by space alone being curved, can I suggest the book 'Exploring Black Holes'. You will find it has nothing to do with your ''electromagnetic waves and space waves''.

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

 

[danshawen]

Check out http://arxiv.org/abs/astro-ph/0310808 :

be sure to also check out:

http://www.scribd.com/doc/236522943...-reading-Davis-Lineweaver-Expanding-Confusion

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, and the wavelength becomes infinite, you have a VIRTUAL photon. A photon is never emitted because no electron ever accelerates. This paper is nonsense. Was it ever peer reviewed by someone competent to do so?

The only way to observe a virtual energy photon from a source outside of our light cone or "teardrop" would be to exceed the speed of light. Allow me to demonstrate this locally.

Pick up a flashlight and hold the back end of it to the back of your head with the business end pointing directly away from anything you can see. Go outside to a location where nothing will interfere with the light of the flashlight reaching the sky. Look down (the flashlight points up). Turn the flashlight on. Turn it off. Assume a normal position and think about what you would need to do if you ever wished to see any of the photons from the flashlight you just turned off. Assume that although they spread out, they never illuminate anything in their path, and so they can never return.

For a galaxy that at about double cosmologically observable distances, assume someone just performed the experiment you did locally and that you would have the means to detect a photon if it ever arrived from there. Sure enough, it would be redshifted so that the frequency was zero, and the wavelength infinite. Do you really expect to be able to detect that photon? The electron that would have produced it can't even move from your perspective. 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.

 

[lpetrich]

Space isn't curved by the Earth's gravitational field. It's curved by an electromagnetic field variation.

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

Think of it like this: when a seismic wave travels through the ground, the ground waves. When an ocean wave travels through the sea, the sea waves. Where an electromagnetic wave travels through space, space waves.

It doesn't, except indirectly through gravity.

And where it waves it curves. Have a google on electromagnetic geometry.

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.

 

[Aqueous Id]

Originally Posted by Farsight
Space isn't curved by the Earth's gravitational field. It's curved by an electromagnetic field variation.

:roflmao:



This just in:

HOUSTON TX - Farsight Opinionated Editorials (F.O.E.), a wholly owned subsidiary of FAUX News:

Amateur Disproves Maxwell's Equations
Gravity Probe B Was A Failure After All, NASA Laments

:roflmao:​

 

[Farsight]

And a non-optical clock?

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.

That's childish. Abysmally childish.

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.

Why don't you demonstrate it to us?

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

Show that the distance invariant S = x[sup]2[/sup] + y[sup]2[/sup] + z[sup]2[/sup] - c[sup]2[/sup]*t[sup]2[/sup] is rotation-invariant, Lorentz-invariant, and reflection-invariant in space coordinates x,y,z and time coordinate t. All you need to do for rotation and Lorentz boosts is to do them in two dimensions each: two space dimensions, and one space dimension and time.

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.

Show why Lorentz boosts are sometimes called hyperbolic rotations. You will have to do some analytic continuation here and there, multiplying some variables by i = sqrt(-1).

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.

Show that the relativistic momentum p and the relativistic energy E satisfy the differential relation dE = v.dp, derived from the work expression dE/dt = F.v.

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.

Lorentz-boost the trajectory of a stationary particle: t = τ, x = y = z = 0. Divide the resulting t,x,y,z by τ. Multiply by the particle's mass. Compare the resulting expressions to the relativistic momentum and energy of that particle. What do you find?

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

Farsight, you must do it with mathematics only. I repeat, mathematics only. No quoting from your heroes, and no trying to make excuses for not doing it. If you are truly capable of doing professional-quality work in relativity, then you must be capable of doing all this by yourself.

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

(Martin Gardner's crackpottery criteria...) On the contrary, some of your theories satisfy #4, and your descriptions of your physics capabilities satisfy #1.

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.