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Mattius_
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Any thoughts on this?
You would absolutely notice if it varied.Originally posted by wimms
you wouldn't notice?
Originally posted by russ_watters
You would absolutely notice if it varied.
I'm not sure what you are asking. Should I list all of the ways the speed of light has been measured and every implication of Relativity that depends on a fixed speed of light?Originally posted by Mr. Robin Parsons
In long frame/form How?
Yes, I'd like to know all the way of measuring speed of light. I'm puzzled, how they measure something that is fundamental to spacetime itself, being source of both standards of time and distance. I've got impression that c is 'measured' the same always.. that leaves some options..Originally posted by russ_watters
I'm not sure what you are asking. Should I list all of the ways the speed of light has been measured and every implication of Relativity that depends on a fixed speed of light?
Originally posted by russ_watters
I'm not sure what you are asking. Should I list all of the ways the speed of light has been measured and every implication of Relativity that depends on a fixed speed of light?
Wimms, measurements are of course all we have to go by. Light has only recently become a standard on which to base measurements BECAUSE it is now known to be a universal constant. Not the other way around. The speed of light has been measured so many ways and under so many different conditions, not to mention the discovery that the speed of light is constant has been used for so many pracical applications, that if it were wrong, we'd know it.Originally posted by wimms
Yes, I'd like to know all the way of measuring speed of light. I'm puzzled, how they measure something that is fundamental to spacetime itself, being source of both standards of time and distance. I've got impression that c is 'measured' the same always.. that leaves some options..
Thats easy. Its the same as the MM experiment just using the sun as the reference point instead of the earth. Any gravitational effects on the speed of light would manifest themselves through measurements at right angles to a the sun. And of course if the Sun's gravity had an effect, so would Earth's.How can we have tested for that?
How do we get 'known distance'? measure time of light travel, right, heh?Originally posted by russ_watters
The easiest way to accurately measure the speed of light is bouncing a laser off a mirror of known distance and measuring the time. The first method I believe had to do with timing the motions of Jupiter's moons. GPS depends on the constant velocity of light. If the speed wasn't constant, GPS wouldn't work.
oh yeah, I want all of them I want to see what is the meterstick with which c is measured.There are more if you want more.
Originally posted by Mattius_
Any thoughts on this?
No, you measure the distance through another means. Like a tape measure.Originally posted by wimms
How do we get 'known distance'? measure time of light travel, right, heh?
Yeah - the time it takes for the signal to travel the distance at C. So you still need C.GPS depends on TIME, not c.
GPS is far too precise to depend on cancelling errors. Also, the error would vary greatly with the azmuth of the satellite.speed of light changes when signal enters atmosphere, doesn't it? This just cancels out.
I already addressed that. Reread my last post.If all this does depend on c, then how on Earth can we measure c itself? It simply must appear constant...
"The" meter is a bar of platinum in a case in England (I think) with two notches on it. But its precision is limited and its accuracy changes with atmospheric conditions.I want to see what is the meterstick with which c is measured.
What is tape measure? Platinum bar that depends on environmental conditions? What if tape length changes with variations of C? What if spacetime itself depends on C? Thats the reason why I asked what else depends on C?Originally posted by russ_watters
No, you measure the distance through another means. Like a tape measure.
You don't need C. You need locally uniform average velocity of signal. It could as well be 1/8 of C or sound, GPS would still work like a charm. And yes, GPS receivers are calculating all sorts of compensations. Of course errors cancel out, that's the point of triangulation and averaging.Yeah - the time it takes for the signal to travel the distance at C. So you still need C. GPS is far too precise to depend on cancelling errors. Also, the error would vary greatly with the azmuth of the satellite.
Not sure I got it. You simply assured me that we'd notice. I'm asking if we really would be capable of noticing, and you didn't address that imo.I already addressed that. Reread my last post.
Exactly. Velocity of light has been found to be 'more' stable than any bar, and instead of measuring c precisely, it was dropped and 'defined' from theory, and taken as standard. Big win, but at the same time make C defined through itself. Imo, best definition of C is c=1."The" meter is a bar of platinum in a case in England (I think) with two notches on it. But its precision is limited and its accuracy changes with atmospheric conditions.
No, argument was more like that we don't have any kind of independant from C reference to measure C. Fact that C is constant in any inertial frame, and that timeflow can differ for differing inertial frames, makes one think that length dilations compensate so that velocity of C is measured same, within the frame. Given that C isn't absolute, but only relative, its more like some sort of law of 'conservation of ratio' between spatial extent and time.The argument here seems to be that since we don't know everything maybe there is some effect not yet observed that makes the speed of light vary. Sorry, but science doesn't work that way. Everything we know about light tells us its speed is constant. Does anyone want to present some ACTUAL EVIDENCE that it is not constant?
If something gets in the way then it gets absorbed or reflected as usual. As far as the acceleration goes, photons have no mass.Originally posted by ddr
how do photons jump from zero speed into c or if ther seed is only c what if something gets in the way?
Again, all of the relevant effects are quite well understood.What is tape measure? Platinum bar that depends on environmental conditions? What if tape length changes with variations of C? What if spacetime itself depends on C? Thats the reason why I asked what else depends on C?
Certainly. But since satellites use radio waves, GPS uses C. Please remember that all of the satellites move independently and the Earth rotates. The relativistic effects of these motions *IS* considered when using GPS.You don't need C. You need locally uniform average velocity of signal.
I ugre you to read more about how GPS works. For that matter, read a little bit about the concept of "precision" ie significant digits in ANY calculation. Errors do NOT cancel out, they build up. You learned that in 8th grade science class (if you are an American). Remember the pictures of a target with groupings of arrows illustrating the difference between precision and accuracy? Same unit.Of course errors cancel out, that's the point of triangulation and averaging.
What are you looking for? I gave examples of situations where we would notice. Thats all I can really do for you. If you choose not to believe it, that's up to you.Not sure I got it. You simply assured me that we'd notice. I'm asking if we really would be capable of noticing, and you didn't address that imo.
Sure. But of course that only works if C really is constant. I guess I'll have to repeat it: this isn't an assumption used for convenience, its observed data. C is constant.Imo, best definition of C is c=1.
Given based on WHAT? You haven't given a shred of evidence that C isn't constant.Given that C isn't absolute, but only relative, its more like some sort of law of 'conservation of ratio' between spatial extent and time.
Which is exactly the point: there isn't any reference frame independent of C. Its constant in all frames. Are you suggesting we've never measured C in another reference frame? Again, I'll have to invoke GPS.No, argument was more like that we don't have any kind of independant from C reference to measure C.
We know that C is constant because we measure it and it is always constant. There is no simpler way to explain it than that. If you won't accept that fact, there really isn't any way for me to help you understand the implications of that fact.My point is that how do we know that C is truly constant, and not that whole spacetime fabric is vibrating causing local variance of C along with spatial and temporal deformations etc?
Really? I didn't know that. And that was salt of my this question. I haven't seen anyone describing what would it imply if C would change, fundamental as it is, and how would it be perceived. And not just change of C alone, but together with all that depends on it together with it.Originally posted by russ_watters
Again, all of the relevant effects are quite well understood.
Here we are. You called errors what I called variance of C due to entering atmosphere. I said this variance cancels out because same change in C occurs for signals from any satellite. I also implied they account for different distances C has to travel in atmosphere depending on azimuth. I was not talking about last digit precision errors. But they are canceled by averaging process.I ugre you to read more about how GPS works. For that matter, read a little bit about the concept of "precision" ie significant digits in ANY calculation. Errors do NOT cancel out, they build up.
Russ, I'm not arguing that we measure C as constant, so its not issue of me believing. We can notice variance of C IF we have something given, like spatial extent that is independant from C, or time measure. But do we have that? For eg. if C would speedup, then time to moon should decrease. But if together with speedup of C, timeflow would slow down, then our clock measure of time would be same. In effect, we can't measure change in time to moon, it would produce same time as with constant C. You say we would notice variance of C, but seems to me you assume that there exists space independant from C. Does it? Afaik whole sense of spacetime is that its intimately relating space with time through C.What are you looking for? I gave examples of situations where we would notice. Thats all I can really do for you. If you choose not to believe it, that's up to you.
I'm not in position to give evidence. I ask questions. C is same within any inertial frame. C is same between any inertial frames. What is it? Perception of reality or alice in wonderland?Given based on WHAT? You haven't given a shred of evidence that C isn't constant.
No. My point is that together with change in C our whole reference frame would change. If that includes timeflow, we have very hard time in detecting changes in C.Which is exactly the point: there isn't any reference frame independent of C. Its constant in all frames. Are you suggesting we've never measured C in another reference frame?
I know that Russ. I'm asking myself, WHY is C constant in all inertial frames or interframe comms? 'Its just so' is only one answer. That its fundamental limit due to Planck length per Planck time is another, but here I suggest that perhaps its so because we wouldn't have any reference frame to notice changes in C, and being restricted to measure C in measures of frame that depends on C itself, what else can we detect?We know that C is constant because we measure it and it is always constant.
Special Relativity is the theory that explains why the speed of light is constant. General Relativity is an extension of Special Relativity to explain gravity. If the speed of light were found to be varialbe, then both theories would be proven wrong and all of their implications (which are vast) would be called into question. Besides just the nature of light, that's all we know about time and gravity as well. We'd need to find another explanation for why the rate of the passage of time is variable for example. Gravitational lensing. Gravitational red shift. The "light barrier": (if the speed of light changes, would this "barrier" change too? Matter/energy relationship. The behavior of particle accelerators.Originally posted by wimms
Really? I didn't know that. And that was salt of my this question. I haven't seen anyone describing what would it imply if C would change, fundamental as it is, and how would it be perceived. And not just change of C alone, but together with all that depends on it together with it.
Can you explain to me or point to, what would be implications of it changing? What would change together with C, especially that which we'd have to use as 'meterstick' to measure C itself.
Actually, YOU brought up errors in GPS. And C DOES change (on average) when it passes through the atmosphere as it does when passing through any medium. But the effect of that is different for each satellite because the signal passes through different parts/amounts of the atmosphere. Thats yet another part of the calculations done in GPS recievers. Since its a known effect taken into account in calculations, its not an error and its certainly not offsetting errors.You called errors what I called variance of C due to entering atmosphere. I said this variance cancels out because same change in C occurs for signals from any satellite.
You mean step outside of the universe? Not really an option, is it? And not really relevant either.We can notice variance of C IF we have something given, like spatial extent that is independant from C, or time measure.
Are you saying that you can't measure the speed of a car while inside the car? Why not? Also, relativity talks about different reference frames, not different universes. According to classical mechanics, measuring the speed of anything including light in different reference frames will not necessarily produce the same result. So all you need to do to prove that is to measure the speed of light in different reference frames. And we have.You say we would notice variance of C, but seems to me you assume that there exists space independant from C. Does it? Afaik whole sense of spacetime is that its intimately relating space with time through C.
Except of course this would affect GRAVITY among other things.Suppose C was 1billion times faster. Then objects 1B lyrs away would seem like 1 lyr away, and completely other stuff would appear 1b lyrs away. Does it matter what the actual C is? Nope, only relation between space and time is what matters.
Then you shouldn't use the word "given." And questions on reality are philosophical, not scientific.I'm not in position to give evidence. I ask questions. C is same within any inertial frame. C is same between any inertial frames. What is it? Perception of reality or alice in wonderland?
Again, "why" is a philosophical question. For the purpose of explaining HOW it works, "why" really doesn't matter. Science doesn't answer why. I submit to you that the question is irrelevant for understanding how it works. The universe is the way it is and this is the only universe that's relevant to us. How things would work in another universe doesn't really matter.I know that Russ. I'm asking myself, WHY is C constant in all inertial frames or interframe comms? 'Its just so' is only one answer. That its fundamental limit due to Planck length per Planck time is another, but here I suggest that perhaps its so because we wouldn't have any reference frame to notice changes in C, and being restricted to measure C in measures of frame that depends on C itself, what else can we detect?
My point is that how do we know that C is truly constant, and not that whole spacetime fabric is vibrating causing local variance of C along with spatial and temporal deformations etc?
Special Relativity is the theory that explains why the speed of light is constant.
Fundamental postulate 'explains'?Originally posted by russ_watters
Special Relativity is the theory that explains why the speed of light is constant.
We need to find that out anyway. Why you think we'd need to throw all out of window? Who said that C can change 'freely' and independant from anything else?General Relativity is an extension of Special Relativity to explain gravity. If the speed of light were found to be varialbe, then both theories would be proven wrong and all of their implications (which are vast) would be called into question. Besides just the nature of light, that's all we know about time and gravity as well. We'd need to find another explanation for why the rate of the passage of time is variable for example.
I have read books. But nowhere have I seen coherent approach to what would change in C imply to all of the physics. Only bits here and there, but no complete picture. I wonder if we even can have such picture before we have complete understanding of all underlying fundamentals.This is starting to get big. Have you read any books on this? "A Brief History of Time" would be a good start. I can't give you a 150 page book in one post.
sigh. Please reread posts. I was talking about C variance due to entering atm and that it cancels out for usable satellites. I didn't call that errors. There is no way to account for fluctuations in atm due to weather, and these are canceled out by averaging samples over time.Actually, YOU brought up errors in GPS. And C DOES change (on average) when it passes through the atmosphere as it does when passing through any medium. But the effect of that is different for each satellite because the signal passes through different parts/amounts of the atmosphere. Thats yet another part of the calculations done in GPS recievers.
Are you chasing ghosts? That was precisely my point! We can't step outside, thus all we can measure is relations between what we observe. And if C underlies all of what we observe, we have hard time to measure its variance. And why isn't this relevant?You mean step outside of the universe? Not really an option, is it? And not really relevant either.
Are you saying that speed of car affects space around it, gravity, timeflow, physical processes to same extent as C does? IF together with car speedup exactly proportional time speedup occured, what speed change could you measure from inside a car?Are you saying that you can't measure the speed of a car while inside the car? Why not?
Is that end of story? Have we reached the 'finish'? As I've understood, relativity put things into correlation so we can compute, not explained 'why'.After relativity explained why, and tecnology provided the means, it became possible to measure TIME in different reference frames.
Of course. It would affect everything. And if it would affect everything in such a way that all would change proportionally, how would we go for detecting such C change? And if we can't detect it directly, doesn't it make you wonder that it might manifest itself as something else, eg GRAVITY? I'm asking, I'm curious how we'd observe it manifesting itself.Except of course this would affect GRAVITY among other things.
Whats wrong with word 'given'? Do you attribute some special meaning to 'given' that I as nonenglish person don't get? For me, what SR says is given.Then you shouldn't use the word "given."
nah. "Why" is the driving question. Without it, science has no purpose and no function. "How" is substitute until we get to the "why". Question is relevant, because to answer it we'd need to have deeper insight into how things work.Again, "why" is a philosophical question. For the purpose of explaining HOW it works, "why" really doesn't matter. Science doesn't answer why. I submit to you that the question is irrelevant for understanding how it works.
Noo. I'm not asking the question in that sense. I'm inquiring what fixes C to appear constant in any inertial frame? Is there possibly a reason for that to seek? And so I ask, would we notice change in C at all if it affected all that we can observe? Or would we notice only indirect effects of that, like time variance or gravity, or matter?And what you are describing is a chicken vs egg scenario.
I'm not arguing this. There is tiny detail though, our theories say that C appears constant for any frame by any measurements. This is different than saying that it IS constant. This difference leaves some room to ponder what would be indirect evidence if C changed in such a way that our direct measurements wouldn't detect it.Originally posted by Hurkyl
That's when we apply Occham's Razor. If the whole of spacetime is conspiring to make any variation in c unmeasurable, then we can get no wrong answers by presuming c does not vary in our theories.
"The fact that the speed of light is a constant in nature is DUE ONLY TO THE FACT THAT FREE SPACE HAPPENS TO HAVE A SPECIFIC PERMEABILITY & PERMITTIVITY. We do not know why this is. Maxwell's equations do not know why this is. The only thing that Maxwell's equations say is: "given this fact that the permeability and permittivity seem to be constant, the speed of light will be constant too." In regions where the permeability and permittivity is NOT constant, the speed of light is also not constant (such as in layered dielectric materials in modern fiber-optic cables). I assure you that the Maxwell equations can very happily accommodate a light-speed that is not constant!"Just to be picky, it was Maxwell's electrodynamics that explained "why" the speed of light is constant; Special Relativity just dealt with the consequences of that constancy.
The word "given" is followed by an accepted fact. If what follows is not an accepted fact, then the word "given" doesn't apply. Yeah, its an English thing.Originally posted by wimms
Whats wrong with word 'given'? Do you attribute some special meaning to 'given' that I as nonenglish person don't get? For me, what SR says is given.
Hello, when did I say anything about experiment? Are you confusing me with someone? I'm asking what would be implications of C changing? And is there a possibility that we wouldn't detect changes in C by direct measurements but instead as some other phenomena?Originally posted by russ_watters
1. The expierment you want done has already been done, or at the very least covered by other experiments.
Strings. 10+ dimensions. what the heck are they doing then? Why are they wondering about 10+ dimensions if "universe is conspiring against us"? Go bash them out of waters.2. As Hurkyl so eloquently put it, if the laws of the universe are "conspiring against us" to make it unobservable, then there is no possible experiment that will ever be able to show a VSL even if it exists.
Who says it can never be observed? What I meant is that it might prove difficult to detect by straightforward means, what macroscopic measurements are. Let me think of one effect that doesn't change how the laws of the universe work: uniform motion. Let's ignore it? If not light and "windows", you'd do this?3. If the effect can never be observed and it doesn't change how the laws of the universe work, you can (and should) ignore it.
Apologies. Wisp/wimms - simlilar names, similar threads.Originally posted by wimms
Hello, when did I say anything about experiment? Are you confusing me with someone?
repost: Special Relativity is the theory that explains why the speed of light is constant. General Relativity is an extension of Special Relativity to explain gravity. If the speed of light were found to be varialbe, then both theories would be proven wrong and all of their implications (which are vast) would be called into question. Besides just the nature of light, that's all we know about time and gravity as well. We'd need to find another explanation for why the rate of the passage of time is variable for example. Gravitational lensing. Gravitational red shift. The "light barrier": (if the speed of light changes, would this "barrier" change too? Matter/energy relationship. The behavior of particle accelerators.And is there a possibility that we wouldn't detect changes in C by direct measurements but instead as some other phenomena?
Maybe I shouldn't have ignored this. Relativity isn't a postulate, its a theory and all of its implications are theories. You're still looking at the issue backwards - relativity depends on the speed of light being constant, not the other way around. Maybe this is the key.Fundamental postulate 'explains'?
No, Einstein already found that out. Or rather he PREDICTED it and later experiments verified it (at the time, clocks weren't accurate enough to detect it).We need to find that out anyway [re: variable time].
Time dilation results directly from a constant C. If C were found to not be constant, time dilation would have to have another cause.Why you think we'd need to throw all out of window?
Relativity is the underlying fundamental and its implications are the big picture.I have read books. But nowhere have I seen coherent approach to what would change in C imply to all of the physics. Only bits here and there, but no complete picture. I wonder if we even can have such picture before we have complete understanding of all underlying fundamentals.
You certainly implied it:Who says it can never be observed?
My point is that how do we know that C is truly constant, and not that whole spacetime fabric is vibrating causing local variance of C along with spatial and temporal deformations etc?
The answer to your question is now and always has been SR. You ARE trying to refute it whether you know it or not.My very question IS how would it change the laws of universe? Do YOU know? Or are you just 'ignoring' questions? Somehow, without me ever giving reason, you started to defend SR as if I was refuting it.
String theory is an attempt to unify Relativity and QM. It does not change my point #2. Or rather, point 2 does not change string theory.Strings. 10+ dimensions. what the heck are they doing then? Why are they wondering about 10+ dimensions if "universe is conspiring against us"? Go bash them out of waters.
Fundamental postulate thing addressed above: this isn't one. But maybe we're getting somewhere now: you're now saying there IS evidence that C is not constant. Could you be more specific? Specifically changes in C that "are called something else." You're saying we have observed C to not be constant? Are you talking about refraction? Clarify.You asked what's the evidence that C changes. There's plenty, it changes in presence of matter, in BEC. Does TIME flow differently there? Vacuum isn't exactly empty, its full of EM and G fields. Does this change C? There are changes in C, but they are called something else. And I still don't understand why its 'stupid' to seek for reasons why C appears constant in any frame, instead of just endlessly repeating conclusions derivered from fundamental postulate.
Right. If you see I'm off, please don't ignore. Let me get this straight: fundamental postulate of SR is that speed of C is constant (relative to any frame, not some absolute space), and from this and other assumptions it works out a theory that is in amazing correlation to observable. That makes this model very viable in that it explains 'how' things relate. So we basically go ahead and assume that C IS constant. From there, we bend space fabric and timeflow that SR initially assumes to have independant existence. Our point of reference becomes C, not space, not time.Originally posted by russ_watters
Maybe I shouldn't have ignored this. Relativity isn't a postulate, its a theory and all of its implications are theories. You're still looking at the issue backwards - relativity depends on the speed of light being constant, not the other way around. Maybe this is the key.
Exactly. He 'modeled' how to predict it. He didn't explain 'WHY' it happens, or even mechanism of 'HOW' it happens. Thats left to be found.No, Einstein already found that out. Or rather he PREDICTED it and later experiments verified it (at the time, clocks weren't accurate enough to detect it).
All-or-nothing. Is world black&white? Maybe time dilation that goes in pair with space dilation always results in same velocity C for observer?Time dilation results directly from a constant C. If C were found to not be constant, time dilation would have to have another cause.
No. I implied that we can't observe it NOW because we have no theory that predicts that and offers means to detect it. My stress was on word 'never'.(Who says it can never be observed?)
You certainly implied it:
SR is NOT and answer. In QM they even question existence of space that SR takes for granted. Nature of time is mystery. I'm not trying to refute SR. SR is in the end a bunch of equations that interconnects space, time and motion of energy. At best you might say I'm wondering if SR could be expanded or perhaps rephrased from different ground.The answer to your question is now and always has been SR. You ARE trying to refute it whether you know it or not.
Whats the point of #2 then?String theory is an attempt to unify Relativity and QM. It does not change my point #2. Or rather, point 2 does not change string theory.
I'm about permittivity and permeability. I quoted for Hurkyl claims about Maxwell equations that underlie constancy of C. Could you comment? Obviously in presence of matter things change. One can explain it with other theories and debunk me, but just consider, if its not matter that 'resists' C in matter, but infact that matter IS manifestation of changes in C. c2[mu]0ε0 = 1Fundamental postulate thing addressed above: this isn't one. But maybe we're getting somewhere now: you're now saying there IS evidence that C is not constant. Could you be more specific? Specifically changes in C that "are called something else." You're saying we have observed C to not be constant? Are you talking about refraction? Clarify.
My point is to get things into perspective for myself.It certainly appears to me that you have a point to your questions. But you are trying very hard to not argue it. Make your point. If it has some validity, we will accept it. If it doesn't we well tell you why and YOU must accept it. But running from a discussion of your point won't help you prove it.
Thats a different issue, but an interesting theory nonetheless.Originally posted by SamBuckler
Just finished reading Faster Than The Speed of Light by Joao Magueijo ISBN 0-434-00948-2 (if you're curious)...
You keep using those words. I don't know where you are getting them and I don't know how else to say it: The fact that C is constant in all reference frames is IMPERICAL DATA. Its not a postulate, assumption, stipulation, or other baseline position made for mathematical convenience. You're still looking at Relativity backwards.fundamental postulate of SR is that speed of C is constant...So we basically go ahead and assume that C IS constant.
"Why?" is a philosophical/religious question. But Einstein most certainly did explain "HOW?" it happens. "HOW?" is the mathematical derivation itself. And the question of whether a mathematical model is a real extension of a physical reality is an interesting one, but it is also largely philosophical. As far as scientists are concerned, if it makes an accurate prediction, its a real extension of physical reality.He 'modeled' how to predict it. He didn't explain 'WHY' it happens, or even mechanism of 'HOW' it happens.
I'm going to have to invoke Occam's razor again. It makes more sense to conclude from observing through imperical data that shows C is a constant and T is a variable, that C is a constant and T is a varible. You're going back to 'the universe is conspiring against us' position again.Maybe time dilation that goes in pair with space dilation always results in same velocity C for observer?
You have it almost exactly backwards. You don't need a theory to know how to observe something. And generally, before you can have a theory, you need the data. You're putting the cart before the horse. Example: The MM experiment confused the hell out of M&M, but it was data and they accepted it. It was years later that a theory was constructed that adequately explained their data. The exception is theories that are built on other theories.I implied that we can't observe it NOW because we have no theory that predicts that and offers means to detect it.
Discarding the theory completely can hardly be called "rephras[ing]" it. It can of course be expanded - and that's not even close to the same as what you are proposing. Example: Newton vs Einstein's gravity.At best you might say I'm wondering if SR could be expanded or perhaps rephrased from different ground.
String theory is an example of expansion - but it doesn't change the fundamental principles of relativity. It does not claim VSL. Just like the above, you're confusing expanding on a theory with discarding it completely. There is a huge difference.Whats the point of #2 then?
Sounds like you already know that scientists have a different explanation from what you prefer.Obviously in presence of matter things change. One can explain it with other theories and debunk me [re: evidence that C isn't constant]
Sure. Those quotes display a lack of understanding of the mechanism behind refraction. Or to be nice, the variability of C is a mathematical convenience, used in refraction calculations, which leads to a very common misunderstanding of the mechanism behind refraction. I'd bet my last paycheck that quote came from a site who'se purpose is to try to refute relativity.I quoted for Hurkyl claims about Maxwell equations that underlie constancy of C. Could you comment?
bs. constant C is very first sentence of SR. its literally postulate. That the ideas to create SR came from empirical data is irrelevant. And value for c isn't even part of SR. And that it matches empirical data is the only reason its accepted.Originally posted by russ_watters
You keep using those words. I don't know where you are getting them and I don't know how else to say it: The fact that C is constant in all reference frames is IMPERICAL DATA. Its not a postulate, assumption, stipulation, or other baseline position made for mathematical convenience. You're still looking at Relativity backwards.
Are you saying that all scientists as positivists? I see two-sided razor here, on one side this is nice way to be open for unexpected ideas, but on other hand this is nice way to close you eyes on possibilities."Why?" is a philosophical/religious question. But Einstein most certainly did explain "HOW?" it happens. "HOW?" is the mathematical derivation itself. And the question of whether a mathematical model is a real extension of a physical reality is an interesting one, but it is also largely philosophical. As far as scientists are concerned, if it makes an accurate prediction, its a real extension of physical reality.
Exactly about this I am talking. Is there a possible mechanism due which we observe C always as constant.Also, mechanisms are unnecessary here and are somewhat linked to the "why?". What is the mechanism by which C stays constant? Dunno - maybe a later theory will answer that. Maybe its just something God decided. Either way, it doesn't change the fact that C is constant and it doesn't change the theories that use the fact that C is constant.
I'm not about conspiring. I'm about possiblity that variations cancel out for us. 10 spatial dimensions that no one can ever detect is consipiring. Go apply your razor on strings.I'm going to have to invoke Occam's razor again. It makes more sense to conclude from observing through imperical data that shows C is a constant and T is a variable, that C is a constant and T is a varible. You're going back to 'the universe is conspiring against us' position again.
bs again. Whole criteria for being theory is requirement to offer predictions that can falsify theory. I've never heard of empirical data about strings. Have you?You have it almost exactly backwards. You don't need a theory to know how to observe something. And generally, before you can have a theory, you need the data. You're putting the cart before the horse. Example: The MM experiment confused the hell out of M&M, but it was data and they accepted it. It was years later that a theory was constructed that adequately explained their data. The exception is theories that are built on other theories.
Whats the bloody matter with you? What makes you say I'm discarding it? I've never said C is observable as VSL. I repeat: I'm ASKING if variations of C could manifest itself as some other phenomena.Discarding the theory completely can hardly be called "rephras[ing]" it. It can of course be expanded - and that's not even close to the same as what you are proposing. Example: Newton vs Einstein's gravity.
Er, what does fundamental principles of relativity has to do with precise value of C in specific point of universe?String theory is an example of expansion - but it doesn't change the fundamental principles of relativity. It does not claim VSL. Just like the above, you're confusing expanding on a theory with discarding it completely. There is a huge difference.
I don't prefer anything. I'm inquiring of possibility. If I'll need to compute, I'll use methods that scientists have accepted. This doesn't forbid me from inquiring unconventional ideas. AND this doesn't forbid you from explaining why they'd be ruled out.Sounds like you already know that scientists have a different explanation from what you prefer.
Could you please explain in simple way, what do you mean? Are you saying that c is same inside water, air, fiber?Sure. Those quotes display a lack of understanding of the mechanism behind refraction. Or to be nice, the variability of C is a mathematical convenience, used in refraction calculations, which leads to a very common misunderstanding of the mechanism behind refraction. I'd bet my last paycheck that quote came from a site who'se purpose is to try to refute relativity.
I just looked it up. You're right. I stand corrected. It is a postulate. However, the fact that it is based on imperical evidence is to me very important. You say its the "only reason its accepted" and that's fine. Its a damn good reason.Originally posted by wimms
bs. constant C is very first sentence of SR. its literally postulate. That the ideas to create SR came from empirical data is irrelevant... And that it matches empirical data is the only reason its accepted.
Certainly possibilities exist. Possibilites ALWAYS exist. But without any evidence to support the existence, "possibility" isn't enough to build a new theory or challenge an existing one.You say these components do not exist. I'm not saying they do, I'm asking if the possibility exists that they might.
Thats your point, not mine, so you tell me. I'm sticking to the obvious answer: we observe C to be constant becaus C is constant.. Is there a possible mechanism due which we observe C always as constant. Any theory that will answer that must explain why we observe C as a constant.
I know significantly less about string theory than I do about relativity. But this discusion is about relativity and relativity *IS* falsifiable.Whole criteria for being theory is requirement to offer predictions that can falsify theory. I've never heard of empirical data about strings.
The implications of the "yes" answer (if verified) that you appear to desire are that relativity and other major theories would need to be discarded. Its a loaded question. The answer is of course yes because of the word "could." Could I grow wings and fly? Yes, but its not likely.Whats the bloody matter with you? What makes you say I'm discarding it? I've never said C is observable as VSL. I repeat: I'm ASKING if variations of C could manifest itself as some other phenomena.
...and it does.then we must accept that meaning of distance must vary accordingly
YES. The principle of refraction is dependent on AVERAGE speed through a medium. The mechanism is that when light hits an atom, it gets absorbed and re-emitted. The delay associated with this causes a change in the APPARENT speed of light through that medium. When moving from one atom to another inside a medium (and anywhere else for that matter), light is traveling through a vacuum and travels at C.Are you saying that c is same inside water, air, fiber?
Sure it is. Thats why its called theory not fancy idea. But notice how things went, first they measured c by approx means. People assumed ether existed and c depends on it (LET). Then Maxwell equations predicted that c is constant, and offered way to calculate c precisely. By then there were questions about invariance of c. Then MM made their experiment, and bummer. Then came SR to turn over the world.Originally posted by russ_watters
However, the fact that it is based on imperical evidence is to me very important. You say its the "only reason its accepted" and that's fine. Its a damn good reason.
Thats interesting, because in other thread you went quite far to show that possibilities do NOT always exist. I'm not challeging existing SR. As to "possibility", if it exists to build a theory that explains "more" than existing ones, then this is "enough" to go for it. This is not to say that I offer some new theory, but to merely justify 'what if' thinking as an excercise.Certainly possibilities exist. Possibilites ALWAYS exist. But without any evidence to support the existence, "possibility" isn't enough to build a new theory or challenge an existing one.
Russ, don't challenge me to offer consistent theory, you realize well that I'm not equipped to do that in form you'd ever accept as truth. I AM sticking with same answer as you if it comes to betting your last check.Thats your point, not mine, so you tell me. I'm sticking to the obvious answer: we observe C to be constant becaus C is constant.
NO. I do not agree that implications are what you think. Any theory has "Domain of Applicability". For SR, one of its components is postulate of const C, for variable C it simply wouldn't be applicable. This doesn't mean SR is wrong, it only means that variations of C are outside scope of SR. Its a loaded questions yes, but not in the sense you wish to imply.The implications of the "yes" answer (if verified) that you appear to desire are that relativity and other major theories would need to be discarded. Its a loaded question.
Exactly. And this means that rulers change. Now question is: what are we measuring, and with what rulers, if rulers themselves aren't absolute? The only answer is that relationship between the rulers is constant C. And that too with restriction to equivalent frames.re: then we must accept that meaning of distance must vary accordingly
...and it does.
Really? Where can I find a source to back this up? Anything I've seen claims c itself differs in medium.YES. The principle of refraction is dependent on AVERAGE speed through a medium. The mechanism is that when light hits an atom, it gets absorbed and re-emitted. The delay associated with this causes a change in the APPARENT speed of light through that medium. When moving from one atom to another inside a medium (and anywhere else for that matter), light is traveling through a vacuum and travels at C.
Right. C is observed constant. Length and time varies. The very dimensions of velocity.Originally posted by Integral
With this understanding you must understand why the main body of Phyiscs pretty much distains the chriping of the crackpots who doubt the constancy of c. It has withstood a centruy and a half of intense scrunity and it will continue to stand as a fundamental constant.
I do make my sincere effort. Its damn frustrating to see that every thinking attempts of nonauthorty is bashed to a crackpot category. Yes, I'm not able to express myself as clear as you'd wish. I Can't express more clearly than I've already have: I DO respect SR. Thats why I'm ASKING, not making statements.My advise to the naysayers is to make an effort to understand the current state of knowledge,
Refraction angle can't be explained by particle behaviour.
Heh, yeah or the history of physics. Thanks though.Originally posted by Integral
Russ,
You are doing an execellent job defending the correct positon, but as a ME it is clear that you have not been exposed to a full blown course in E&M.
Anywhwere you care to look, wimms. Any book or site that explains the mechanism and not just the usage of refraction. Start with google.Really? Where can I find a source to back this up? re: refraction
Obviously, as I said, I did. Everywhere I look, they say c is lower in medium.Originally posted by russ_watters
Anywhwere you care to look, wimms. Any book or site that explains the mechanism and not just the usage of refraction. Start with google.
[?] [?] There is another thread on this board about it. You've posted in it. But could you post some links that you looked at that confirm your belief? I suspect the sites are all high school physics type sites that only talk about refraction in a Newtonian sense.Originally posted by wimms
Obviously, as I said, I did. Everywhere I look, they say c is lower in medium.
http://www.glenbrook.k12.il.us/gbssci/phys/Class/refrn/u14l1d.htmlWhen the wave impinges upon a particle of matter, the energy is absorbed and sets electrons within the atoms into vibrational motion. If the frequency of the electromagnetic wave does not match the resonant frequency of vibration of the electron, then the energy is reemitted in the form of an electromagnetic wave. This new electromagnetic wave has the same frequency as the original wave and it too will travel at a speed of c through the empty space between atoms. The newly emitted light wave continues to move through the interatomic space until it impinges upon a neighboring particle. The energy is absorbed by this new particle and sets the electrons of its atoms into vibration motion. And once more, if there is no match between the frequency of the electromagnetic wave and the resonant frequency of the electron, the energy is reemitted in the form of a new electromagnetic wave. The cycle of absorption and reemission continues as the energy is transported from particle to particle through the bulk of a medium. Every photon (bundle of electromagnetic energy) travels between the interatomic void at a speed of c; yet time delay involve in the process of being absorbed and reemitted by the atoms of the matter lowers the net speed of transport from one end of the medium to the other. Subsequently, the net speed of an electromagnetic wave in any medium is somewhat less than its speed in a vacuum - c (3 x 108 m/s).
Looks like another "why" question to me. But I'm not sure I'd use the same concepts in a vacuum that you'd apply to a medium. A vacuum isn't a medium per se.Even if we say that retardation of light in such fields is only apparent slowdown of c, this doesn't say anything about reason vacuum itself has specific permittivity/permeability