The Speed of Light is Not Constant

[Grumpy]

Farsight

And accepting that Einstein said the speed of light varies with position.

It varies only in it's coordinate speed, not it's actual speed through spacetime, just like Einstein said in GR. Again, the dishonest out of context(and corrected in Wiki)crap you think trumps the in context statements that he put in his Theory.

The speed of light in vacuum, c, is a universal physical constant important throughout physics. Its value is exactly 299,792,458 meters per second. This is 186,000 miles per second, or about 670 million miles per hour. According to special relativity, c is the maximum speed at which all energy, matter, and information in the universe can travel. It is the speed at which all massless particles and associated fields (including electromagnetic radiation such as light) travel in vacuum. It is also the speed of gravity (i.e. of gravitational waves) predicted by current theories. Such particles and waves travel at c regardless of the motion of the source or the inertial frame of reference of the observer. In the theory of relativity, c interrelates space and time, and also appears in the famous equation of mass–energy equivalence E = mc^2.

"... light is always propagated in empty space with a definite velocity [speed] c which is independent of the state of motion of the emitting body."

A. Einstein

Light itself does not vary, the coordinate speed of light DOES vary with position in a gravity field. Here's why...

Curved spacetime is a longer path than coordinate distance, simple as that.

Grumpy

 

[Read-Only]

We've already covered this with James R. Light does not go slower because the distance increases. If this was true distances at the black-hole event horizon would have to be infinite. Also note that only one-tenth of the Shapiro delay is down to the light taking a curved path. When one contrives a Shapiro-like delay wherein a light beam passes between two stars in close proximity, it doesn't curve at all. It's a straight-line path, and space isn't curved.

I understand these simple things. You don't, and it seems, you don't want to.

No, it's YOU who does not understand those simple things. You can deny it all you want - is just shows your HUGE arrogance and failure to even attempt to understand. I believe that is one definition of a fool and it fits you perfectly.

 

[OnlyMe]

You're 65?

Good point!

 

[OnlyMe]

Okay, OnlyMe. I understand where you're coming from now. You were cautioning BOTH 'sides' on that. My apologies for mistaking your implication.

So, are you also rejecting the validity of the 'moving light clock' depictions and illustrative device used by Grumpy in his 'mainstream SR arguments' based on assumptions/conclusions inherent in same, and what you call 'abstract not real' clocks/setups?

I have not seen the parallel mirror light box used exactly as Grumpy does, but as I said it has been a long time since I cracked open a text book using that kind of graphic example. Still Grumpy and I diverge in how we conceptually incorporate GR as a description of reality. Without intending to talk for Grumpy, he sees GR as an accurate description of reality such that gravity is caused by the real curvature of space and time. While I am uncertain of the mechanism from which gravitation emerges and understand GR as a predictive 4D geometric model, that accurately describes how objects we observe interact within the context of gravitation. For me GR remains an abstract theoretical model, or rather has returned to that status... From my perspective gravitation may look like curved spacetime, while it is in reality emergent from some non space/time related phenomena. But that was worked out in a discussion in another thread.

So though I have not seen parallel mirrors used as Grumpy does, what he describes is consistent with how I understand GR... Given an understanding of the conceptual shift described above...

 

[OnlyMe]

My red highlighting in your above quote.

Mate, to be fair to Farsight, I must point out that the NIST clock example was used in explanations as to the definition of the second per se, as a first/separate issue from how that initial 'standard defined' second is LATER observed/predicted to be affected by local differences in GR predicted effects on clocks. So your criticism there is based on conflation by you of the two separate aspects/issues involving NIST/second and the GR effects/using second etc etc as so far discussed already.

That's all I wanted to point out, mate! Cheers.

Farsight has more than once linked the NIST optical clocks and his mirror clock gif, in discussions where more than just a definition of the second was involved.

 

[OnlyMe]

The NIST optical clock runs slower when its lower.

This much has been experimentally demonstrated.

So will a quartz wristwatch. So will a mechanical clock. So will the gedanken parallel-mirror light clock used extensively in relativity.

None of the these clocks have been experimentally tested with respect to time dilation. So the conclusion remains an application of theory.., IOW theoretical.

The parallel mirror light clock is still an artifact of imagination. So what would happen in that case can only be thought of as theoretical, at best.

The exception is the grandfather clock, where the clock rate depends on the gradient in gravitational potential rather than on gravitational potential itself.

A grandfather clock functions differently than cesium and optical clocks, but then so do quartz and mechanical (spring wound) clocks. It is my position that while time dilation is supported by the from cesium and optical clocks, until it has been duplicated with other mechanisms of measuring time, perhaps quartz or spring wound clocks.., or some other form of change, the application of the optical clock conclusions remain to reality as a whole remains theoretical.

 

[Grumpy]

OnlyMe

The light clock as I used it is a comic book level explanation of what we see in the real Universe. These guys don't even understand at that level, evidently.

Maxwell showed that lightspeed is always measured the same, that led directly to Einstein's theory. It helps in conceptualizing the reality of the consequences of Relativity to a constant lightspeed, from whatever frame in whatever frame. SR only explained speed(among many other things), it was not a complete theory until Einstein showed constant lightspeed through local spacetime in a vacuum is always invariant under acceleration as well. The theory is a construct, it does not follow that it is therefore a faulty construct in describing reality. If the Universe behaves just like your theory predicts it will behave, that is as certain as you can be in science, where all theories are subject to comparison to reality, all error is in your construct, reality is as it is.

Grumpy

 

[paddoboy]

Thanks to Read Only, PhysBang, Grumpy, and Only Me, for reinforcing the common sense mainstream approach to this long and drawn out battle.
None [or more correctly neither] of our alternative theorist pushers have offered anything concrete to evidence that light/photons travel at anything other then "c".
I'm pretty satisfied now that anyone looking into this thread, will see the common sense, evidenced model of light speed being constant, as generally inferred, and never being observed any differently.
So I'll leave this now for our two antagonists to froth and carry on all they like....
One or both may now have me on ignore [I'm in good company] and I certainly don't want to be the cause of anymore emotional instability,
Plus the thread is obviously over the last couple of days or so, being dragged down into the mire.
I will though keep my eyes and ears open on the off "non zero" chance that this crazy alternative idea is finally peer reviewed and accepted.


Thank you linesman, thank you ballboys!

 

[Undefined]

Hi OnlyMe.

Wow, for someone who hasn't kept up with the experimental sciences, you still want to dictate to Farsight about what is or is not valid illustrative clock scenarios in GR? You want it both ways, don't you, mate?

When you and Grumpy et al actually take a moment to stop kneejerking from abstrcat/past SR views which are INVALID in GR local effects reality observable as predicted by Einstein/GR, and start to understand the difference between the 'constant c' (the TERM/SYMBOL for a 'c' usually set to '1' as a constant IN that equations) and the 'invariant c' (which is actual real value FOR lightspeed determined using the local in-frame CLOCK 'second' AS AFFECTED FROM any 'standard second' such that since the 'time' second interval has CHANGED then the actual lightspeed has also, hence the proportionate RESULTANT calculation in every frame is the 'invariant c' PROPORTIIONATE value, NOT actual lightspeed IN-frame where the 'time' dilation makes the measurement ALWAYS come out to that same 'proportionate 'invariant c').

Please stop kneejerking and insulting from your old 'comic book SR' views and 'understandings, and start listening and understanding the local REAL view as to what's happening for REAL, not abstractly.


OnlyMe, please also read on this 'constant c' and 'invariant c' difference, and especially note what I wrote about the LENGTH CONTRACTION abstraction not being reality, in my reply to you in the "Gravity Works Like THis" thread, post #477. Thanks.

Cheers.

 

[OnlyMe]

Hi OnlyMe.

Wow, for someone who hasn't kept up with the experimental sciences, you still want to dictate to Farsight about what is or is not valid illustrative clock scenarios in GR? You want it both ways, don't you, mate?

When you and Grumpy et al actually take a moment to stop kneejerking from abstrcat/past SR views which are INVALID in GR local effects reality observable as predicted by Einstein/GR, and start to understand the difference between the 'constant c' (the TERM/SYMBOL for a 'c' usually set to '1' as a constant IN that equations) and the 'invariant c' (which is actual real value FOR lightspeed determined using the local in-frame CLOCK 'second' AS AFFECTED FROM any 'standard second' such that since the 'time' second interval has CHANGED then the actual lightspeed has also, hence the proportionate RESULTANT calculation in every frame is the 'invariant c' PROPORTIIONATE value, NOT actual lightspeed IN-frame where the 'time' dilation makes the measurement ALWAYS come out to that same 'proportionate 'invariant c').

Please stop kneejerking and insulting from your old 'comic book SR' views and 'understandings, and start listening and understanding the local REAL view as to what's happening for REAL, not abstractly.


OnlyMe, please also read on this 'constant c' and 'invariant c' difference, and especially note what I wrote about the LENGTH CONTRACTION abstraction not being reality, in my reply to you in the "Gravity Works Like THis" thread, post #477. Thanks.

Cheers.

What?

Try it without all of the personal comment.

 

[Undefined]

What?

Try it without all of the personal comment.

You conveniently IGNORE all the personal comments made by the others, and just zero in on mine in response, all so you can evad actually acknowledging the information content that shows you and others have been talking out of your math/abstraction hats while missing the insights/import of consulting the GR clock effects local reality under your nose? What does it take to shake out all those 'cop out' EXCUSES and RATIONALIZATIONS for DENYING THE BLEEDING OBVIOUS when it's presented to you ON A PLATE, mate? Wow, stubborn ego much?

 

[Grumpy]

RC

Were you talking to yourself? Lots of people project, that's what every comment in you last appears to be. It is you that doesn't understand Relativity or reality, as evidenced by the meaningless word salad you keep using. Starting off your discussion by denying known facts, like the constant and invariant c, is not rational, neither is anything that follows that major error.

Grumpy

 

[OnlyMe]

You conveniently IGNORE all the personal comments made by the others, and just zero in on mine in response, all so you can evad actually acknowledging the information content that shows you and others have been talking out of your math/abstraction hats while missing the insights/import of consulting the GR clock effects local reality under your nose? What does it take to shake out all those 'cop out' EXCUSES and RATIONALIZATIONS for DENYING THE BLEEDING OBVIOUS when it's presented to you ON A PLATE, mate? Wow, stubborn ego much?

I don't ignore anyone or how they chose to post. You just happen to post comment, devoid of anything but personal comment or so entangled with personal comment, as reply to a post of mine. As I said earlier I don't comment on all posts I have some disagreement, or agreement with.

... Now re-read your own post quoted above and tell me where a discussion of fact or theory, is separated from personal comment...

To be certain, we all at one time or another, get drawn into similar discourse. A hazard of engaging in what amounts to an argument rather than discussion.

 

[Farsight]

None of the these clocks have been experimentally tested with respect to time dilation. So the conclusion remains an application of theory.., IOW theoretical.

We are confident that relativity is a good theory.

The parallel mirror light clock is still an artifact of imagination. So what would happen in that case can only be thought of as theoretical, at best.

We are confident in our use of the parallel mirror light clock in relativity. We are confident that were we to devise a working clock of this ilk, it would go slower when it was lower.

A grandfather clock functions differently...

Yes, the force of gravity makes the pendulum swing. The force of gravity relates to the gradient in potential. Other clocks' clock rates depend on gravitational potential rather than the gradient in gravitational potential.

than cesium and optical clocks, but then so do quartz and mechanical (spring wound) clocks. It is my position that while time dilation is supported by the from cesium and optical clocks, until it has been duplicated with other mechanisms of measuring time, perhaps quartz or spring wound clocks.., or some other form of change, the application of the optical clock conclusions remain to reality as a whole remains theoretical.

Then your position is that you are doubting relativity. Don't.

 

[OnlyMe]

We are confident that relativity is a good theory.


Then your position is that you are doubting relativity. Don't.

Since you agree that relativity is a theory, how is it that a prediction of that theory that has not yet been experimentally confirmed, is more than theoretical?

My comments were not doubts of relativity. They were as has been the case, an attempt to draw a line between what remains theory and theoretical interpretations and what has been experimentally proven.

Time dilation is a prediction that has universal implications. We have only experimentally confirmed it, in a limited sense. There is a significant difference between the mechanisms involved in the electron transition frequencies associated with cesium and similar optical frequency clocks and how change occurs in other types of clock mechanisms, as well as the complex mechanisms of aging.

There is a difference between the initial limited confirmation of time dilation, associated with cesium and optical clocks and how we project that initial confirmation to other mechanisms involving change.

 

[Undefined]

Hi Grumpy.

RC

Were you talking to yourself? Lots of people project, that's what every comment in you last appears to be. It is you that doesn't understand Relativity or reality, as evidenced by the meaningless word salad you keep using. Starting off your discussion by denying known facts, like the constant and invariant c, is not rational, neither is anything that follows that major error.

Grumpy

Read the latest posts across the threads to others also, Grumpy. It may be you are mistaken, not I. Possible, hey? Especially given the discussion so far. Anyway, Cheers and take care, mate. Bye for now.

 

[Undefined]

I don't ignore anyone or how they chose to post. You just happen to post comment, devoid of anything but personal comment or so entangled with personal comment, as reply to a post of mine. As I said earlier I don't comment on all posts I have some disagreement, or agreement with.

... Now re-read your own post quoted above and tell me where a discussion of fact or theory, is separated from personal comment...

To be certain, we all at one time or another, get drawn into similar discourse. A hazard of engaging in what amounts to an argument rather than discussion.

Wasn't it you just recently mentioned CONTEXT? I make the posts in the overall context of all the discussions in associated threads covering these matters. I expect you to have regard for that cross-thread discussions context. Thanks.

Anyway, I already and more than once posted Einstein's own words and insights/explanations re 'time'; his 2nd Postulate 'GR 'rider' stating SR 'constancy of light' view invalid in GR contexts; and his clear statement that he was ABSTRACTING from the reality via his 'spacetime' construct.

And also I explained the difference between the equations TERM 'constant c' and the real RESULTANT 'invariant c' measurement via affected clock and light propagation rates complementing in the GR-affected in-frame locally real GR effects/rates observation.

And all you have is more 'persona stuff' and opinions in reply? Ok. Good luck with that, mate.

 

[paddoboy]

Read the latest posts across the threads to others also, Grumpy. It may be you are mistaken, not I. Possible, hey? Especially given the discussion so far. Anyway, Cheers and take care, mate. Bye for now.

The discussions so far, plus the red herrings thrown in, have shown that the speed of light is constant.
Photons always travel at "c"
Deeper in a GR gravity well, they appear to travel slower, only because they have a longer distance to travel [space/time curvature] and higher in a gravity well, they "appear" to travel faster [less space/time curvature] because they have less distance to traverse.
But photons always travel at "c"

Anything with mass, can never reach the speed of light
Anything without rest mass [photons] can never travel at anything other then "c"

 

[Undefined]

The discussions so far, plus the red herrings thrown in, have shown that the speed of light is constant.
Photons always travel at "c"
Deeper in a GR gravity well, they appear to travel slower, only because they have a longer distance to travel [space/time curvature] and higher in a gravity well, they "appear" to travel faster [less space/time curvature] because they have less distance to traverse.
But photons always travel at "c"

Anything with mass, can never reach the speed of light
Anything without rest mass [photons] can never travel at anything other then "c"

You haven't understood any of it, let alone what you think you 'know' about it from mainstream. Mate, don't make yourself look a more silly ass than you already did in my "How can real energy 'permeate space-time'..." thread, ok? It's too excruciating painful (funny yes, but still painfully tragic) to watch you go on making yourself sillier looking with every silly clueless pretender post. Stop! Then go do/learn better, paddo,

 

[paddoboy]

You haven't understood any of it, let alone what you think you 'know' about it from mainstream. Mate, don't make yourself look a more silly ass than you already did in my "How can real energy 'permeate space-time'..." thread, ok? It's too excruciating painful (funny yes, but still painfully tragic) to watch you go on making yourself sillier looking with every silly clueless pretender post. Stop! Then go do/learn better, paddo,

Yes, I do understand a great deal of it and probably more then you as it appears we are both layman.

As I have mentioned...the Universe expands...An Unknown force mainstream call it DE is what we think is responsible for the acceleration in the expansion rate......then we have the Casimir effect.
The BB of course was an evolution of space and time [which we now call space/time] that came along with a "Superforce" permeating all of space/time. or a single force composing all of the four currently known forces.
As temperatures and pressures dropped, the superforce started to decouple....From there matter came into being as the pressures and temperatures dropped even further.
That's the most likely scenario, although the closer back to t=0 we get, the less certain the scenario is.
All in all, it is a logical backward extrapolation of what we now see.

Now getting back to the question in hand.....
the speed of light is constant.
Photons always travel at "c"
Deeper in a GR gravity well, they appear to travel slower, only because they have a longer distance to travel [space/time curvature] and higher in a gravity well, they "appear" to travel faster [less space/time curvature] because they have less distance to traverse.
But photons always travel at "c"

Anything with mass, can never reach the speed of light
Anything without rest mass [photons] can never travel at anything other then "c"


If you have any different thoughts, you know what to do.
Your unscientific words, your pseudoscientific claims, your personal insults, your bizzare behaviour, calling everyone trolls that disagree with you, does nothing for your demeanor.