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Tir21

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With emphasis mine:

 

 

Not just "mainstream" but a simple fact: experiments that clearly use a one-way light path and find isotropy are inherently unable to rule out a large class of theories in which the one-way speed of light is anisotropic

- http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#one-way_tests

 

( Yes I'm back :) )

 

While that may be true, it's up to us to demonstrate that by means of scientific arguments. Mud throwing is particularly unscientific.

PS I read: "In 2010 the Telesio - Galilei Academy of Science awarded Professor Reg Cahill a Gold Medal for the development of Process Physics. The ceremony was held at the University of Pecs, Hungary."

- http://www.flinders.edu.au/science_engineering/caps/staff-postgrads/info/cahill-r/process-physics/

 

Not bad for a "crank"!

Sigh

 

The remark from the John Baez website is very poorly phrased. The class of theories he's talking about is the class of "test theories" "

 

-Edwards

-Robertson-Mansouri-Sexl

-Standard Model Extension

 

By virtue of being test theories, they inherently must ASSUME that light speed is anisotropic and they assign a set of parameters in order to model the said anisotropy. Experiments constrain these parameters to values that disprove the initial assumption of anisotropy.

 

As to Reg Cahill, a quick look at his publications and at "

" and at the Telesio-Galilei"academy" says it all. Edited by zztop
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Sigh

 

The remark from the John Baez website is very poorly phrased. The class of theories he's talking about is the class of "test theories" "

 

-Edwards

-Robertson-Mansouri-Sexl

-Standard Model Extension

 

By virtue of being test theories, they inherently must ASSUME that light speed is anisotropic and they assign a set of parameters in order to model the said anisotropy. Experiments constrain these parameters to values that disprove the initial assumption of anisotropy.

[..]

 

While the phrasing there could be better, I disagree that the physics FAQ there is "very poorly phrased". This concerns a fundamental point of SR, directly related with the topic at hand. The simultaneity convention is just that, a convention. Choose another convention and you "make" the speed of light anisotropic in your rest frame. You do not need to assume the light speed to be isotropic wrt your system of reference; it's merely convenient to do so.

 

Therefore, Einstein rephrased the second postulate as follows in 1907 (emphasis mine):

 

"We [...] assume that the clocks can be adjusted in such a way that the propagation velocity of every light ray in vacuum - measured by

means of these clocks - becomes everywhere equal to a universal constant c, provided that the coordinate system is not accelerated."

- http://www.soso.ch/wissen/hist/SRT/E-1907.pdf

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While the phrasing there could be better, I disagree that the physics FAQ there is "very poorly phrased". This concerns a fundamental point of SR, directly related with the topic at hand. The simultaneity convention is just that, a convention. Choose another convention and you "make" the speed of light anisotropic in your rest frame. You do not need to assume the light speed to be isotropic wrt your system of reference; it's merely convenient to do so.

 

Therefore, Einstein rephrased the second postulate as follows in 1907 (emphasis mine):

 

"We [...] assume that the clocks can be adjusted in such a way that the propagation velocity of every light ray in vacuum - measured by

means of these clocks - becomes everywhere equal to a universal constant c, provided that the coordinate system is not accelerated."

- http://www.soso.ch/wissen/hist/SRT/E-1907.pdf

Correction: it is the COORDINATE-dependent speed of light that "becomes anisotropic". PROPER speed of light is isotropic (and equal to "c" in vacuum).

PROPER light speed in a uniformly accelerated system as well as in a uniformly rotating system is also isotropic and equal to "c".

In other news , the Flinders University finally unloaded the Cahill embarrassment. They finally got the crank out.

Edited by zztop
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Correction: it is the COORDINATE-dependent speed of light that "becomes anisotropic". [..]

 

Good. :)

There are plenty of people who have done good, or even excellent Nobel Prize winning, work but are still cranks. Laithwaite, Hoyle, Andrulis, Tesla, Newton, Crick, ... I'm sure there are hundreds of others.

 

Newton and Tesla were cranks you say? Hmm, maybe - but how poor science would have been without them! :P

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Er, yeah. That was kind of my point....

 

More importantly, this is why an argument from authority is a fallacy.

 

Yes, exactly!

PS. did you notice that, apparently, for saying exactly the same things in perfect agreement, some forum participant gave me -1 point of appreciation and you +1 point? ... and I bet that that same individual will want to give me -2 points for exposing it! :P

Edited by Tim88
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zztop.

What is the news on Reg Cahill??

I see that he is now Emeritus. He must have retired (70yrs). But he still has a phone & office it seems.

I wonder what a free-range Reg Cahill will do. Lots of youtube, lots of seminars.

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zztop.

What is the news on Reg Cahill??

I see that he is now Emeritus. He must have retired (70yrs). But he still has a phone & office it seems.

I wonder what a free-range Reg Cahill will do. Lots of youtube, lots of seminars.

He has been retired by the faculty. Due to being an (in)famous crank.

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Tim88 post#50.

Thanx for the link to Tom Roberts' & Siegmar Schleif's website re What Is The Experimental Basis of Special Relativity.

I refer to their wording in their Section 3 re Einstein's second postulate......... Any speed of light moves in the "stationary" system of coordinates with determined velocity c, whether the ray be emitted by a stationary or by a moving body.

 

I like this wording (compared to other wordings that i have seen). It is of course itself made up of two postulates, hencely we should talk of three postulates not two, the third being that the velocity of the emitter does not affect the determined velocity c.

 

But i want to mention the second postulate -- which now becomes simply.......

Any speed of light moves in the "stationary" system of coordinates with determined velocity c.

 

Here it is clear to me that Einstein doesn't say that light moves with velocity c -- he says that light moves with determined velocity c.

That makes sense to me.

SR & GR are models, & in these models u have rules for determining the velocity of c (& other things). Then u continue to follow the rules & u determine other numbers. And u relate these numbers to numbers determined by others using the same model. And everyone lives happily ever after.

Re the real velocity of c -- who cares?? It is unlikely to worry anyone unless they have a very accurate clock.

Edited by madmac
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Here it is clear to me that Einstein doesn't say that light moves with velocity c -- he says that light moves with determined velocity c.

 

 

1. You mean "what Roberts and Schleif say"

 

2. What is the difference between "velocity" and "determined velocity"? Do you think light can move at a different speed than we measure?

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Strange.

Wiki says ....... "As measured in any inertial frame of reference..." etc.......... which is similar.

 

Yes, the velocity c must depend on the method of measuring (determining). If one uses a special method of measuring based on a special model then that might be ok for some applications.

But if it doesn't give true c then eventually a problem will arise, in which case science will investigate & discover new knowledge (benefiting mankind) , or, science will fudge & the fudge will be rewarded with a Nobel (benefiting one man).

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Tim88 post#50.

Thanx for the link to Tom Roberts' & Siegmar Schleif's website re What Is The Experimental Basis of Special Relativity.

I refer to their wording in their Section 3 re Einstein's second postulate......... Any speed of light moves in the "stationary" system of coordinates with determined velocity c, whether the ray be emitted by a stationary or by a moving body.

 

I like this wording (compared to other wordings that i have seen). It is of course itself made up of two postulates, hencely we should talk of three postulates not two, the third being that the velocity of the emitter does not affect the determined velocity c.

 

But i want to mention the second postulate -- which now becomes simply.......

Any speed of light moves in the "stationary" system of coordinates with determined velocity c.

 

Here it is clear to me that Einstein doesn't say that light moves with velocity c -- he says that light moves with determined velocity c.

That makes sense to me.

SR & GR are models, & in these models u have rules for determining the velocity of c (& other things). Then u continue to follow the rules & u determine other numbers. And u relate these numbers to numbers determined by others using the same model. And everyone lives happily ever after.

Re the real velocity of c -- who cares?? It is unlikely to worry anyone unless they have a very accurate clock.

 

First of all, their translation may make you read something in there that wasn't intended. The German word "bestimmten" merely means "certain" or "definite", as also so translated here: http://fourmilab.ch/etexts/einstein/specrel/www/ (in the intro)

Further, as you can also see in the intro of Einstein's paper, that whole phrase is the second postulate; it simply characterizes light as a wave. A wave has a certain or constant speed c, as it is independent of the speed of the source.

 

Nevertheless you are right that the "speed of light" as defined in SR, following Einstein's lead, is a "determined" speed based on a measurement convention - as specified in §1. And according to the theory, even accurate clocks cannot help to change that.

Edited by Tim88
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Strange.

Einstein doesn't need a true c. And, he has an infinite number of possible c's, or at least only limited by the number of observers. And Einsteinians obviously get goodish answers lots of the time.

If there is a true c (ie only one truly stationary frame) then SR & GR cannot be correct (as he knew), or not 100% correct, or only correct in certain instances (whatever).

We hear of lots of things that prove Einstein correct, forgetting that there is no limit to the number of theories that can accord with any experimental result.

 

Tim88.

Yes, i see that in the intro they don't use the word determined nor the word measured. Although i notice that in Section 2 the wording of the postulate (called principle at this stage) is similar or identical to the wording i mentioned earlier, ie using the word determined.

 

I see that the intro also says -- "The introduction of a "luminiferous ether" will prove to be superfluous....... " -- which accords with the statement i often make that Einstein didn't rule out an aether, he merely made it redundant. Which sort of resonates with my above comments to Strange.

 

Tim88.

U say..... A wave has a certain or constant speed c ......

This reminds me that i need to start a new thread in Speculations. Your statement depends on the definition of a wave.

I already knew of the problem (that i thought of, i didn't read it anywhere), but it surfaced again (i say again because i first saw it when i read Hicks' calibration of M&M)(1905) when i read an article using one of your links (or someone else's here), where it said that Einstein took Newton's 0.87 arcsec to 1.75 arcsec mainly by using the bending of light (as it passed the Sun) by virtue of redshift. But i wont go into it now. I am just flagging that your seemingly simple wave statement (& Einstein's redshift methodology) might not be so simple. And this has nothing to do with aether.

Edited by madmac
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And, he has an infinite number of possible c's, or at least only limited by the number of observers.

 

 

No. There is only one. That is the whole point.

 

 

 

Einsteinians

 

There is no such thing. Just because your worldview is dictated by your religious beliefs, doesn't mean that others are similarly gullible.

 

 

 

get goodish answers lots of the time.

 

In other words, the theory works.

 

 

 

If there is a true c (ie only one truly stationary frame)

 

There is no truly stationary frame. That is a complete non sequitur.

 

 

 

We hear of lots of things that prove Einstein correct

 

I don't think Einstein performed any experiments to test SR or GR.

 

And nothing is ever proved correct in science.

 

 

 

there is no limit to the number of theories that can accord with any experimental result.

 

Nonsense.

 

 

 

Einstein didn't rule out an aether, he merely made it redundant.

 

At which point Occam's Razor comes into play. Bye bye aether.

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