Why is the speed of light the same relative to any frame of reference?

[jdavel]

metachristi said: "Still it (the ether) is a fruitful theoretical construct from which, in conjunction with the principle of equivalence of the laws of physics in all inertial frames, we can deduce the standard Lorentz transfomations, supported by empirically known facts, making also new predictions."

How do you get from an ether and the principle of equivalence to the "Lorentz transformations supported by empirically known facts"?

Is this what you're saying?: Assume an ether, and the principle of equivalence. Then observe length contraction and time dilation. Then deduce the Lorentz transformations where c is constant relative to the ether?

If so, why is that a better theory than this (SR)?: Assume the principle of equivalence. Then deduce the Lorentz transformations. Then verify by measuring length contraction and time dilation.

 

[metacristi]

How do you get from an ether and the principle of equivalence to the "Lorentz transformations supported by empirically known facts"?

When I said iIt' I was talking about the invariance of the speed of light in all inertial frames.No aether involved there.As for the rest here is another try (I am aware that my english profficiency is not very good).Einstein's postulates are based on observational data but they are not the only ones which could lead to roughly the same observed facts (experimentally confirmed).Basically there could exist an infinity of explanations for the same observational evidence,we cannot deduce explanations from facts.As I've already said there is even possible to obtain from the assumptions of the invariance of the speed of light+accepting only the dilation of time as experimental evidence (the contraction of length is not proved experimentally) some variants for the Lorenz transformations for which we have perfect synchronization for all inertial frames (which is compatible with the existence of an aether,let's say Bohm's quantum potential).This is why we cannot say that Bohm's interpretation of QM cannot be Lorenz invariant.This is still possible,of course with the expense of changing the form of Lorenz transformations.Still since there are no reasons for the existence of an aether (be it in the form of a quantum potential) there are no good reasons also to prefer such transformations.If we could somehow find sufficient reasons,experimentally based,that the aether exist then things would change dramatically.Not the case as of now.The principle of sufficient reason and empirical evidence (the number of empirical confirmations of a hypothesis) are at the base of science,since Bacon at least,they assured the privilege of science and the actual method of the scientific method over other systems of beliefs.Otherwise we should accept everything as being equally valid (as irrationalists claim) clearly not the best approach.They still have to prove why do we have the science as we know it and not a science based on Homer's Gods for example.

 

[selfAdjoint]

This is why we cannot say that Bohm's interpretation of QM cannot be Lorenz invariant.This is still possible,of course with the expense of changing the form of Lorenz transformations.

Don't raise the bridge, lower the river?

 

[metacristi]

This is why we cannot say that Bohm's interpretation of QM cannot be Lorenz invariant.This is still possible,of course with the expense of changing the form of Lorenz transformations.

Don't raise the bridge, lower the river?

Well from all I know there is very serious work now attempting to construct a relativistic form of Bohm's Interpretation of QM (though some other physicists,the majority in fact,think it's impossible).Nothing is set in stone,since we can only obtain sufficient reasons backed by observed facts,not prove or deduce our enunciations from observations.Even those assumptions accepted intially with sufficient reasons (from all what we know at a certain moment) are still fallible knowledge,open to revise.for example now we have no good reason to think that an aether exist due to Michelson Morley's negative result indeed still some new data could change things dramatically (as I've argued before) by potentially providing sufficient reasons supporting the existence of the aether.

 

[metacristi]

How does it do that?

We always start from natural explanations,according with the principle of sufficient reason,but over time facts make the difference.In neurological field for example currently there is absolutely no reason to suppose that consciousness involves something more than the functioning of the neural netwotrk of the brain,virtually all neurologists will not accept qualia as being a 'hard problem' as many philosophers propose (ask those who have been at Tucson conference this year).Still some new direct/indirect evidence or at least if qualia could be introduced in our scientific theories by making potentially testable predictions would dramatically change things.

They can? Would you care to try?

Tycho Brahe's data was compatible in Kepler's time either with a very complicated variant of Ptolemy's hypothesis and the Copernican view as modified by Kepler,the copernican system had evolved empirically and theoretically (at some time before it was even inferior).Now they were equally valid on empirical grounds indeed so scientists preferred one or another on other criterions (the majority preferred tradition,I wouldn't say because of religious pressures in science).The relative simplicity of Kepler's proposals did not convince many to accept it,only some mavericks did.Kepler for example invoqued some mystical causes for his preference.Still on longer term it was the considerable empirical success of Newtonian physics (Kepler's laws can be deduced from it) which convinced scientists to switch.It was fully visible now the ad hoc status of Ptolemy's system.More or less the same pattern happened later with Einstein when he first saw Kaufmann's results.He acknowledged that Abraham's and Bucherer's models were favorized by those data,still he considered his model 'confirmed' (hope you understood I do not mean proved or made more probable) by that experiement for the differences were extremely small.He explained that he did so because whilst his theory was able to encompass a wide range of phenomena,the alternative models were extremely ad hoc.Further empirical confirmations gave sufficient reasons to reject those ad hoc alternatives.There might not exist instant rationality but on long term,as in the lakatosian model,definitely there is a method assuring the rationality of scientific changes,the primacy of the scientific method.Irrationalists still have to prove the success of induction (based on the principle of sufficient reason in majority,for example when inferring the causes of an observed effect) and why do we have currently the actual scientific body of knowledge and not a system based on the Greek Gods for example (if this really is possible,I do not think it could be made viable).Finally,contrary to what some might object,the bayesian view is a strong 'tool',widely used in science,there are even underway very serious efforts to back the stronger form of Occam's Razor/principle of parsimony (the simpler hypothesis is more likely to be true).

 

[Hugo Holbling]

Now they were equally valid on empirical grounds indeed so scientists preferred one or another on other criterions (the majority preferred tradition,I wouldn't say because of religious pressures in science).

This is quite false: Kepler and Copernicus both had religious reasons for adopting their ideas as well as those based on neoplatonic and hermetic ideas, particularly from Philolaus. It was because of these that Copernicus insisted that orbits must be spherical and it took Kepler so long to arrive at the ellipse.

Kepler for example invoqued some mystical causes for his preference.

Indeed he did, as did most others of that time and plenty since. Your faith in Lakatos ignores more recent philosophy of science such as the work of Holton.

Still on longer term it was the considerable empirical success of Newtonian physics (Kepler's laws can be deduced from it) which convinced scientists to switch.It was fully visible now the ad hoc status of Ptolemy's system.

This is also false, while your use of the term "scientist" is anachronistic. I suggest you actually read the Principia (in Cohen's translation) and try to factor in something other than "empirical success", since you'll find that for those like Newton and Einstein the belief came first and the "empirical success" second. That brings us to:

He explained that he did so because whilst his theory was able to encompass a wide range of phenomena,the alternative models were extremely ad hoc.Further empirical confirmations gave sufficient reasons to reject those ad hoc alternatives.

On that contrary, Einstein's approach and epistemology are far more complex. These reasons are philosophical in the first place, but he also discounted Kaufman from a faith in his ideas that could not be shaken (indeed, it seems he didn't respond at all when asked to comment on D.C. Miller's later falsification of his theory). Holton's studies have amply demonstrated this additional "dimension" (as he puts it), but a story i like goes thusly:

When asked by one of his students how he felt about the correct predictions for Eddington's expedition to measure the eclipse in 1919, he replied "but i knew that the theory is correct." When the student asked how he would have felt if the prediction had not been confirmed, he answered "then i would have been sorry for the dear Lord - the theory is correct."

There might not exist instant rationality but on long term,as in the lakatosian model,definitely there is a method assuring the rationality of scientific changes,the primacy of the scientific method.

What is this method that you merely assert?

Irrationalists still have to prove the success of induction (based on the principle of sufficient reason in majority,for example when inferring the causes of an observed effect) and why do we have currently the actual scientific body of knowledge and not a system based on the Greek Gods for example

Why do they have to do that? This is a rather massive non sequitur, but i might ask if you can "prove the success of induction" (whatever that means)?

Finally,contrary to what some might object,the bayesian view is a strong 'tool',widely used in science,there are even underway very serious efforts to back the stronger form of Occam's Razor/principle of parsimony (the simpler hypothesis is more likely to be true).

Instead, Bayesian theory is anything but taken for granted and subject to significant critique. Of course, i needn't explain why because it seems we deal here only in assertions. Parsimony is likewise problematic and it's doubtful that verisimilitude applies, even before we get to the Bohr's objection that the consequences of additional hypotheses are never clear a priori and can only be evaluated after the fact.

What i was wondering, in asking my questions before, was if you have any reasons for your assertions or if they are indeed just that?

Edited to add: on second thought, forget it. I give up.