Why physicists refuse to measure the one-way speed of light directly?
in [Physics]
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From: Ace0f_5pades on 13 Jan 2010 01:54 On Jan 12, 6:48 am, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > kenseto wrote: > > Why physicists refuse to measure the one-way speed of light directly? > > You confuse "refuse" with an inability to do so accurately enough to be useful. > > The problem with any one-way measurement is that the systematic errors are > large. So large that competing theories cannot be distinguished via this method. > > For round-trip measurements the situation is quite different. From pre-1983 > measurements it is known that the round-trip speed of light in vacuum in any > earthbound laboratory is within 1 meter/sec of the currently defined value. That > is, after all, the rationale behind the redefinition of the meter. > > > The answer: [...] > > Ken's "answer" is nonsense. But yes, today the International Standards > Organization defines the speed of light in vacuum to be constant, and they > define the meter in terms of the speed of light and their definition of the second. > > [You REALLY don't understand this, and like a hamster in a wheel > you keep re-tracing old steps without getting anywhere.. Don't > expect me to respond until you LEARN something about this.] > > Tom Roberts Hey Tom, read some of your outline in http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html will go over it in time. can I ask you to take part in the thought experiment too @ http://groups.google.com/group/sci.physics/browse_thread/thread/e01480c15e001830?hl=en# I'm not sure if it others have already determined the cahnge in Relative PE as outlined in the thought experiment, perhaps you'll know?
From: kenseto on 13 Jan 2010 09:43 On Jan 12, 9:20 pm, GogoJF <jfgog...(a)yahoo.com> wrote: > On Jan 11, 7:59 am, kenseto <kens...(a)erinet.com> wrote: > > > Why physicists refuse to measure the one-way speed of light directly? > > The answer: > > The one-way speed of light is physical distance dependent. > > BTW that's why they invented a new definition for a meter length: 1 > > meter=1/299,792,458 light second > > Using this definition the one-way speed of light is c by definition. > > > Ken Seto > > Ken: You keep going about your business, demanding why a one-way, > unidirectional measure of light should not be performed. So far, all > that I have heard is that- the isotropy of light automatically implies > a one-way measure of c, the fact that anisotropy does not exist (MM) > means that light is isotropic and that the two-way would average out, > that there is 2x in summation divided by 2, that a one way measure > would lead to errors beyond the usefulness of the experiment, that it > is not meaningful, that it is not possible to perform, and, last, but > not least, that it is not useful. Sure it is useful. The two way speed of light is measured with the current definition for a meter: 1 meter=1/299,792,458 light-second. This means that you don't have to measure the physical distance between the source and the reflecting mirror. All you need to do is measure the return time for the light pulse and divid that by 1/299,792,458 to get a guaranteed defined value for light speed. This is not a true measure for the two way speed of light because you are using light speed to measure light speed. A TRUE MEASURE FOR THE TWO WAY SPEED OF LIGHT IS AS FOLLOWS: 1. measure the physical distance between the source and the reflecting mirror with a physical ruler or tape....call this L_r. 2. Measure the time for the light pulse to return to the source....call this T_r 3. The two-way speed of light=L_r/T_r 4. Repeat these procedures for different physical distances between the source and the reflecting mirror. The above procedure will be able to determine if the two way speed of light is also distance dependent as predicted by any correct ether theory. Physicists refuse to measure the one-way speed of light because it is not possible to use the current defintion for a meter to make such a measurement. The one-way speed of light must be measured as follows: 1. Measure the physical distance between the clocks.....call this L_c. 2. measure the time needed for the light pulse from the source clock to arrive at the distant clock....call this T_c 3. The one-way speed of light=L_c/T_c. 4. Repeat these procedure for different physical distances between the two clocks The above procedure will be able to determine if the one-way speed of light is distance dependent as predicted by any correct aether theory. Ken Seto
From: Tom Roberts on 13 Jan 2010 11:06 GogoJF wrote: > Tom Roberts wrote >> Your paper chose to use one of Einstein's methods to synchronize >> the two "Omni light sources" A and B. That's a reasonable method, >> but it is not unique. > Could you please reference > Einstein method which is identical to mine. Sure would appreciate it. I have no specific reference, but it probably appears in: Einstein, _Relativity_. One of his methods to synchronize two clocks at rest in an inertial frame is to place a light source equidistant from both and use a light pulse emitted from the source to start the two clocks at the same value when the light pulse is received by each. Note that this assumes that the speed of the light pulse is isotropic in the inertial frame being used. That's what you did, re-naming the components. Tom Roberts
From: Da Do Ron Ron on 13 Jan 2010 16:12 eric gisse suggested: >I'd suggest reading about it. Look, if it were that damn simple, why would Andie panic & plonk, and why would Uncle Tom and PDiddy take the A train? I have read about it, extensively, which is precisely why I put the question to Tom. Perhaps you, Gisse, can help Tom answer? ~~RA~~
From: xxein on 13 Jan 2010 20:20
On Jan 11, 6:48 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > Sam Wormley wrote: > > On 1/11/10 12:01 PM, glird wrote: > >> On Jan 11, 11:22 am, Sam Wormley wrote: > >>> Physics FAQ: How is the speed of light > >> measured? > >> [snip] > >>> http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html > > >> I looked and found this written therein: > >> "At this time there are no direct tests of length contraction, as > >> measuring the length of a moving object to the precision required has > >> not been feasible. There is, however, a demonstration that it occurs: > >> "A current-carrying wire is observed to be electrically neutral in > >> its rest frame, and a nearby charged particle at rest in that frame is > >> unaffected by the current. A nearby charged particle that is moving > >> parallel to the wire, however, is subject to a magnetic force that is > >> related to its speed relative to the wire. If one considers the > >> situation in the rest frame of a charge moving with the drift velocity > >> of the electrons in the wire, the force is purely electrostatic due to > >> the different length contractions of the positive and negative charges > >> in the wire (the former are fixed relative to the wire, while the > >> latter are mobile with drift velocities of a few mm per second). This > >> approach gives the correct quantitative value of the magnetic force in > >> the wire frame. This is discussed in more detail in: Purcel, > >> Electricity and Magnetism. It is rather remarkable that relativistic > >> effects for such a tiny velocity explain the enormous magnetic forces > >> we observe." > > >> It is rather remarkable that DESPITE THIS EXPERIMENTAL confirmation > >> of Lorentz's length contraction, present physics still denies that it > >> really happens. > > >> glird > > > Depends on the observer! "Really Happening" is what one measures. > > And moreover, no matter what observers measure, this "length contraction" NEVER > affects the object itself. As that is what a "real contraction" would mean, it's > clear that this length contraction is not a real contraction OF THE OBJECT. > > So one must be careful in how one phrases statements about "length contraction". > There are too many possible meanings of "real" to be able to use that word > without saying what one means by it. > > Tom Roberts- Hide quoted text - > > - Show quoted text - xxein: You lose. |