I’ll try and be brief and will have to leave out argument from modern experiments. My point is not to be right, but about argument. Philosophers have reason to be vitally concerned with what appears at first blush to be a purely physical question (and a rather simple one at that): can we-and if so, how - measure the speed of light on a one- way trip? If classical physics were correct, we could readily give an affirmative answer to the question about the possibility of ascertaining the one-way speed of light, and methods which would be feasible for doing so could easily be devised. Classical physics is not acceptable; it has been superseded by Einstein's special theory of relativity. In his analysis of simultaneity, Einstein considers a situation in which a light ray is sent (in vacuo) from point A to point B where it is then reflected back to A. He remarks that by definition we set the time required for the light to travel from A to B equal to the time required for the light to make the return trip from B to A. This is an astonishing move to make. He says, in effect, that we are free to stipulate, as a definition, that the speed of light on the trip out is equal to the speed of light on the return trip. From the standpoint of classical physics, as well as simple common sense, it would seem that the equality (or inequality) of the speeds in the two opposite directions is a fact of nature. If it is a fact of nature, it must be ascertained empirically, not laid down in the form of a definition. This controversy over the one-way speed of light is an excellent testing-ground for a number of philosophical doctrines concerning conventionality. I’m not questioning the science per se and lack the grok to do so. There is an important tradition-associated with Mach, Poincare, Einstein, and many others-which considers as in-dispensable to physical understanding the careful philosophical analysis of such concepts as mass, distance, space, time, and motion (Georges, unless I’m very wrong, makes much of this). An investigation of the status of the one-way speed of light (or whatever query we can come up with), as fact or convention, can be pursued in the same spirit. How deeply can we claim to understand the physical, even if we are using this word as short-hand, if this concept suffers central logical unclarity? Current scientific developments suggest a further reason for concern about the speed of light. As science progresses, it sometimes becomes advisable to adopt new conventions regarding fundamental physical magnitudes. The wave-length of light in an atomic spectral line has replaced the standard meter bar as the basic standard of length, and atomic frequencies have replaced astronomic time standards. Further changes have no doubt occurred – I’m out of date. An attractive alternative is to give up length as a fundamental physical magnitude, replacing it with the speed of light as a defined quantity. A distance, a meter for example, would then be a derived magnitude - the distance traversed by light in a given amount of time. Time and velocity would thus replace the traditional basic quantities of time and distance. If such a change is made in the foundations of physics - the physics used by real-life physicists who make actual measurements in the laboratory and the world - it would be good to know whether this new fundamental constant is a one-way or a round-trip speed. The basic defined quantity would be the average round-trip speed of light. An additional definition would equate the two one-way speeds. My physics is poor – just what a poor chemist gleans from chats with colleagues, perhaps leading to revisions of his dumb experiments with matter in his common sense on realising if they worked the radiation energies would kill everyone in the lab. This is not my point, nor do I expect to undermine a subject I barely grasp. I’m simply trying to say that some of our reasoning is not about certainty and that recognising and shaking conventions about can help us learn. My applications of this would be in the dumb world of soaked-up idiocy and skilled incompetence masquerading as sense. An example like this might be used to improve someone's grok of SR, something like it might undermine the same. There was enough in this example for experiments to be designed and conducted. There is learning in the thinking and too much learning is prevented by those who discourage daring, impudence or do not have the time to explain why a daft question can be shown to be so.
On 1 Jan, 09:24, Georges Metanomski <[email protected]> wrote: > --- On Fri,measuring the one way> speed of light 1/1/10, archytas > <[email protected]> wrote: > ... > > The point is whether other explorations are possible, as I > > suggest > > they are through reasonable thought even where great minds > > have > > produced theory such as SR which has had great empirical > > confirmation. Thinking about measuring the one way > > speed of light in > > vacuum is one such example. > > =========== > G: > 1.SR is an approximation of GR, like Newton was of SR. > 2."measuring the one way speed of light" is misunderstanding of SR and > silly falling back on Galilean Relativity and Aether. > Or, maybe I got it wrong? You mentioned it, so please, explain what you > mean by it and what new, if anything at all, does it bring. > Cheers, > Georges. -- You received this message because you are subscribed to the Google Groups "Epistemology" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/epistemology?hl=en.
