The Speed of Light is Not Constant

[OnlyMe]

See the OP where I refer to David Wineland talking about the NIST optical clock. An optical clock is like the NIST Caesium atomic clock, but it uses optical frequencies instead of microwave frequencies. The NIST Caesium clock is used to define the second as the duration of 9,192,631,770 periods of radiation. It's like you're sitting in a canoe counting waves passing you by. If those waves are coming at you slower, your second is bigger. But because you count 9,192,631,770 waves before you declare that a second has elapsed, the frequency is then 9,192,631,770 Hertz by definition regardless of how fast the waves are moving. Also see gravitational time dilation on wiki and note where it says electromagnetic radiation and matter may be equally affected, since they are made of the same essence.

I was not asking for a description of NIST optical clocks. I was asking for a reference that describes a real light clock. It has been implied (to be kind in interpretation) that light clocks, as in your gif exist.

Also note my bold emphasis in your above quoted post.

The first, "may" is not the same as "is". It only suggests a possibility not a certainty!

The second in red/bold, is a judgement based on a particular theoretical interpretation.

I raise these issues not as a challenge to the possible accuracy of their description of what may be. Instead I once again, point out that you seem to lack an understanding of the difference between what is known to be, and what remains a theoretical conclusion or statement.

 

[Grumpy]

Russ_Watters

An additional observation is that Einstein stated that any time dependent natural process behaves in a manner that it serves as defining it's own time. It does not matter if it is the radiation frequency of Cesium under certain conditions, the beats of the frequency of a laser beam, the orbital dynamics of three rapidly rotating neutron stars in a extremely close double/single or the imaginary lightclock, they all are valid. It's the lightclock that illustrates relativity best at a comic book level. And we really are dealing with the misunderstanding of Farsight that is at the comic book level.

These diagrams illustrate how the coordinate distance between the two grey triangles stays fixed as the time it takes a photon at lightspeed to transit that coordinate distance increases with speed(in the top two) and acceleration(in the bottom two). The bottom left one is the one pertaining to a clock sitting on or above the Earth's surface, the direction of the ground is to the left. Since this is a stationary frame we see the dotted line as the trajectory of the photon(IE a curved path for the photon back and forth between the mirrors).

Interestingly, Farsight's misleading animation would be accurate for a stationary view in line with the direction of travel/acceleration, 90 degrees through rotation(Hmm, where have I heard that word?)from the side view in my illustration. But the cause of the apparent slower speed is perspective, the cause is what I have presented.

Grumpy

 

[arfa brane]

Also please refer to same posts where I explained that in THIS specific case the only thing we wanted to establish is that GR prediction of effects on light clocks was REAL. That can be accomplished as described SIMPLY and DIRECTLY. You use a PLumb Bob to determine the above/below if you are so pedantic and so incapable of telling that self-evident fact for yourself in the same room as the clocks.

Therefore you are referring to a system of coordinates, in which "up" and "down" are defined by the plumb line. You insist that coordinates are an abstraction that isn't needed, but then demonstrate that this is not true.

What you are talking about is UNREAL co-ordinate overlays on REAL self-evident GR situation. No such overlays are needed to spot that GR effects DO affect the clocks as predicted by GR. The quantification and/or abstract explanations from 'frames' etc is MOOT if we have what we wanted

But you have what you wanted because the clocks are in a coordinate system. You say "no such overlays are needed", then contradict this by saying a plumb line is needed. Why can't you see that you're contradicting yourself?

That you can say, "the plumb bob points in the same up/down direction as gravity", means you are abstracting directions, and as I've said, you can't avoid doing this. Would your life make much sense if you couldn't tell where you are or which direction you were heading in? I think not, and I also think you can do both because you use abstract coordinates constantly, maybe not precisely, but that's irrelevant.

 

[Undefined]

Hi Russ, everyone.

What is the value of the "constant c" and what is the value of the "invariant c"?

The 'constant c' is the TERM in the equations. It has 'c' always put to value '1'.

The 'invariant c' is a measurement-related real lightspeed-and-real-clock-variations based proportionate result when both the frame's clock/riming values and the same frame's actual light propagation rate within that frame 'cancel' out automatically because the VERY SAME physical effects which slows clock 'tick/timing' rate also effect the slower light propagation rate in that same frame conditions which affects the clock.

So whatever the light propagation rate (unknowable directly) in a frame, it is the 'measured speed' BASED on the COMPLEMENTARILY AFFECTED CLOCK TIMING values used FOR that 'measurement' resultant in that frame.

Any complementarity/proportionality RESULTANT 'measurement' value 'output' IN ONE PARTICULAR FRAME'S in-frame 'measurement' using a a frame-affected clock/timing, would ALSO be the SAME (invariant) complementarity/proportionality RESULTANT 'measurement' value 'output' IN ALL OTHER FRAMES' in-frame 'measurements' because there respective frames' clock/timing is accordingly affected/vary in different frame respective conditions.

Hence the 'invariant c' is a REAL same-across-frames RESULTANT 'measurement' value based on respective clock/timing effects involved and used in the 'measurements'.....only it is always output from the complementarity/proportionality frames/effects as alway the same 'c'.

The question therefore arises:

Just because a resultant 'invariant output value' is the same in every frame measurement, does that justify 'putting the EQUATIONs TERM 'c' to ALWAYS equal '1' without reference to the real conditions being 'treated/theorized' VIA the EQUATIONS having a 'constant c' TERM that is INDISCRIMINATELY and AUTOMATICALLY 'put equal to 1' and just forgetting about it and moving on to the treatment/manipulation of the other terms?

Is that a good idea? Is that a good analytical practice? To ignore the reality 'invariant c' aspect where light propagation rate may vary along with clock/timing rate, and so making the automatic ASSUMPTIVE SETTING of the TERM 'c' in the equations to '1' without actually knowing WHAT the light propagation rate actually WAS in a FRAME where both the clock/timing AND the light propagation rate may be affected in reality so the real propagation may have been slower than the 'constant c' UNITARY value/term in the equations later?

That's all the time I have for this at this time, Russ, everyone.

I will leave you all to calmly and carefully ponder the subtle but important differences/implications for yourselves for now. Cheers!

 

[Undefined]

Yes, again with the argument that abstractions lead to problems. Here though, this difference you're talking about exists because the clocks are in different positions, hence it relates (abstractly) the difference in position to the difference in time measured by each clock.

Once again it seems you can't avoid referring to positions and times = a coordinate system. You keep saying you can, but then can only demonstrate that you have to refer to some "difference" that can be measured (so you must be referring to a space in which two abstract distances can be compared), so you haven't done this thing you say you can do, at least not yet.
Whereas I insist that you cannot make any meaningful "physical" statement about clocks or time rates without referring to coordinates. It just doesn't have legs.

Who wants to 'avoid it", mate. It's only IRRELEVANT in this specific setup. Period. Why can't you 'get' that and stop your 'one groove' concern for an IRRELEVANCE in this setup, as already explained more than once? Please stop, arfa. You've been answered and you should understand not kneejerk back again with that patently 'irrelevant bee in your bonnet' as explained already. Thanks. Cheers.

 

[paddoboy]

SR has two main postulates....
[1] The laws of physics are the same in any and all inertial FoR's.

[2] The speed of light "c" in a vacuum is constant.

Hope that helps.

 

[Undefined]

Hi OnlyMe.

Unless you can provide a credible reference to a real light clock, the above seems to be a case of you having convinced yourself that a hypothetical object is real, just by saying so over and over.

In a few words, and a link, exactly what are you referring to as a light clock above?

Mate, why the double standards? No-one is using anything different that the SAME light clock illustrative device which is used by MAINSTREAM physicists illustrating their theoretical MOVING LIGHT CLOCK 'explanations' in SR context.

Only now we are considering the REAL EFFECTS locally of GR (as predicted) on real light clock counterparts that are NOT in abstract reciprocal-equality-perspective 'moving/SR' contexts, but in REAL LOCAL GR STATES predicted by Einstein and REALLY OBSERVED, irrespective of the 'quantitative differences involved in any one two-clock separation case in different GR altitudes.

Why is it that what's good for the goose is NOW all of a sudden NOT good for the gander, mate? How about you all drop these inane/irrelevant DISTRACTION 'objections' and just LOOK at the REALITY in front of you for a change. Sheesh! You lot are so far removed from reality 'by inculcation' that you can't even find your way back to reality even when it's right UNDER YOUR NOSE.b Get real. Stop with the inane excuses/rationalizations/distractions from the REAL THING and discuss the REAL THING and not just your 'preferred fanntasy version/analysis' of same. OK? Thanks.

In a rush again today, and might be very busy again over the next few days. So I will be reading-only for a while after I log out today, so apologies if I miss replying to anyone. Cheers!

 

[Undefined]

SR has two main postulates....
[1] The laws of physics are the same in any and all inertial FoR's.

[2] The speed of light "c" in a vacuum is constant.

Hope that helps.

You forgot the 'rider' Einstein put on the 2nd postulate that makes it valid in SR but NOT valid anymore in GR contexts.

Why persist in your 'comic book version' facile and INCOMPLETE 'hash of a handle' you keep getting on both the orthodoxy and alternatives discussed?

How obtuse and ego-driven are you, anyway, mate, that you miss all the evidence of your 'hash of a handle' way of dictating to others is EMBARRASSING everyone, including those whom you would 'me-too' cheerlead and yourself?

Cool it, dude. You are way below the requisite pay/comprehension grade in these discussions, obviously. No basis at all for you to be making all this 'paddo noise' as if it mattered either way to anyone except your fellow trolls and disrupters. Take a break and re-think your role/agenda here, because you ain't doin so hot up to now. Good luck.

 

[paddoboy]

Cool it, dude. You are way below the requisite pay/comprehension grade in these discussions, obviously. No basis at all for you to be making all this 'paddo noise' as if it mattered either way to anyone except your fellow trolls and disrupters. Take a break and re-think your role/agenda here, because you ain't doin so hot up to now. Good luck.

Really undefined, stop the sickening [uke:] pretense.
I'll refute your rubbish as long as you keep posting rubbish. Got that?

And I'm certainly getting far less criticism than your own trash.
Now again, stop the over the top pretense.

 

[Undefined]

Really undefined, stop the sickening [uke:] pretense.
I'll refute your rubbish as long as you keep posting rubbish. Got that?

And I'm certainly getting far less criticism than your own trash.
Now again, stop the over the top pretense.

You 'refute' anything? Hilarious!

Just more 'paddo noise' from a science-empty troll agenda. Sad.

 

[paddoboy]

For example, in explaining the Shapiro delay, mentioned above, we note that if we assume a flat spacetime then the speed of light seems to slow as the light passes near the Sun. However, if we take the general relativistic description seriously, then the explanation for the apparent slowing of the speed of light is that there is actually more space near the Sun than there would be if the spacetime there was flat, because in fact the spacetime is curved. The light therefore has further to travel, which takes longer, even though its speed through the vacuum remains constant.

And there we have it Ladies and Gentlemen, Boys and Girls.....
The actual speed of light remains constant.

 

[paddoboy]

You 'refute' anything? Hilarious!

Just more 'paddo noise' from a science-empty troll agenda. Sad.

I've successfully refuted you many times...But that was easy.

ps: I thought you were going?
What about the ToE? "nudge, nudge, wink, wink"

 

[PhysBang]

You forgot the 'rider' Einstein put on the 2nd postulate that makes it valid in SR but NOT valid anymore in GR contexts.

But that isn't what Einstein did. He said that its application was restricted.

You are free to use the subtleties of Einstein's claims, but not a gross misinterpretation that turns into a lie.

 

[Undefined]

But that isn't what Einstein did. He said that its application was restricted.

You are free to use the subtleties of Einstein's claims, but not a gross misinterpretation that turns into a lie.

Yes, restricted to SR contexts. Einstein explicitly states that the SR validity of 'constancy of speed of light' view does NOT EXTEND to GR contexts. Period. Any more lame semantics from you on this to evade the bleedin obvious implications so you can troll some more?

 

[Undefined]

And there we have it Ladies and Gentlemen, Boys and Girls.....
The actual speed of light remains constant.

Note James' conditional 'qualifier' covering everything that followed:

...if we take the general relativistic description seriously,

See? ONLY if we take THAT 'interpretation' as 'gospel'. Which we DON'T for the reasons already made clear about both the clock/timing AND the light propagating rate MAY be varying, as per Einstein's 'rider' on his 2nd Postulate IMPLIED/PREDICTED was the case!

paddo, do you even know how to parse/read/comprehend anything written here by anyone at all? You seem to jump to 'me too' cheerleading of stuff that you haven't the first clue about what it is actually saying/assuming/implying/qualifying etc etc. How is that good for you OR the forum discussions, if you just make MORE 'paddo noise' at every turn with mindless regularity irrespective of what you link/quote? Give it a rest, mate! You're scaring the neighbours with all that incessant loudmouthed 'racket' you're making.

 

[paddoboy]

Note James' conditional 'qualifier' covering everything that followed:

All physicists/cosmologist, and I take GR seriously...It's an overwhelmingly successfully supported theory about space/time/Universe/gravity.

You still seem to be copping plenty of flack from most reputable quarters undefined.....and you still seem to manically carry on with your meaningless rants, but like the Gentleman I am, I won't comment on....

 

[PhysBang]

Yes, restricted to SR contexts. Einstein explicitly states that the SR validity of 'constancy of speed of light' view does NOT EXTEND to GR contexts. Period. Any more lame semantics from you on this to evade the bleedin obvious implications so you can troll some more?

Please provide us with your citation.

 

[Russ_Watters]

Russ_Watters

An additional observation is that Einstein stated that any time dependent natural process behaves in a manner that it serves as defining it's own time. It does not matter if it is the radiation frequency of Cesium under certain conditions, the beats of the frequency of a laser beam, the orbital dynamics of three rapidly rotating neutron stars in a extremely close double/single or the imaginary lightclock, they all are valid. It's the lightclock that illustrates relativity best at a comic book level. And we really are dealing with the misunderstanding of Farsight that is at the comic book level.

Yes. And that's what's so bizarre about this: Farsight agrees to the physical reality of time dilation when you beat it out of him. He admits there is no way to distinguish clock differences from actual time dilation because all processes show these differences. So his argument really is completely void. He's arguing nothing.

Interestingly, Farsight's misleading animation would be accurate for a stationary view in line with the direction of travel/acceleration, 90 degrees through rotation(Hmm, where have I heard that word?)from the side view in my illustration. But the cause of the apparent slower speed is perspective, the cause is what I have presented.

Since Farsight has chosen never to define his thought experiment, we can choose the definitions ourselves. Yours indeed could work, but mine is simpler and I think more likely what Farsight intends:

The second clock is using the locally measured distance (which is equal to the first), but the coordinate time (which is longer). It isn't representative of anything you can actually see in reality, but you could construct it via calculation.

 

[paddoboy]

____________________________________________________________________________________________________________________
Originally Posted by James R View Post

For example, in explaining the Shapiro delay, mentioned above, we note that if we assume a flat spacetime then the speed of light seems to slow as the light passes near the Sun. However, if we take the general relativistic description seriously, then the explanation for the apparent slowing of the speed of light is that there is actually more space near the Sun than there would be if the spacetime there was flat, because in fact the spacetime is curved. The light therefore has further to travel, which takes longer, even though its speed through the vacuum remains constant.
______________________________________________________________________________________________________________________

And there we have it Ladies and Gentlemen, Boys and Girls.....
The actual speed of light remains constant.

Since this thread has been labeled to get a rise out of the mainstream quarters, let me add what I just said in another thread of purposeful provocation.....

the speed of light remains constant because it has no mass...If that speed varied at all, then we would need to asign some mass to it....and as far as we know, it is massless.


To further extend a helping hand to the confused, and in relation to the above, it should also be said that if you tried to imagine something that had some rest mass and was then traveling at ''c", it would have infinite "mass"
So logically it follows that anything with zero mass will always be at "c", and anything with any rest mass, will never be able to reach "c"
But I'm sure I have said just as much earlier in one of these threads.

 

[Russ_Watters]

I'm shocked you've decided to answer an actual question:

The 'constant c' is the TERM in the equations. It has 'c' always put to value '1'.

The first sentence is correct, the second is wrong. It is often true that natural units can be used, it most certainly isn't always. For example, the GR time dilation equation that Farsight provided:

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

http://en.wikipedia.org/wiki/Gravitational_time_dilation#Outside_a_non-rotating_sphere

You plug the actual value into that, not the natural units value of 1.

The 'invariant c' is a measurement-related real lightspeed-and-real-clock-variations...

Yes, but that doesn't answer the question.

So. You answered, but only sorta. I asked what is the value? You gave one wrong answer and one non-answer. Do you need a hint or would you like to try again?