I do not have enough evidence to make more sense of this, but if the photon becomes an x-ray because of length contraction, 2 things occur to me.
Firstly if the electron is not passing by enough magnets to gain the required frequency as far as the Lab frame is concerned, then even if the wavelength could seem to be shortened by length contraction (possibly not the SR version either) it still would not explain the frequency. This is however a very complex issue. More clearly, if the electron is emitting a photon at high relativistic velocities, then there should be red/blue shifting depending on if the photon is detected ahead or behind in much the same way that a horn of a car changes pitch depending of if it is receding or approaching. (Doppler) The Doppler effect is funny actually, since it causes an optical illusion of making an approaching object look longer, yet raises frequency of the same, a wavelength could 'look' longer (if we could see wavelengths like objects) as it approaches but have a higher frequency. So if length contraction can explain this, Special Relativity's version would only be applicable in the electron frame since in the lab frame the electron is not moving fast enough and the magnets are too far apart, but clearly the x-ray detector isn't moving relativistically. If it was an x-ray in the Lab frame without the Doppler effect blue shifting, then it should be an even higher frequency in the electrons frame where time dilation and length contraction should make short wavelength and high frequency (of the lab frame) seem shorter and higher still. Of course that becomes circular reasoning where all motion (other than Doppler) should make a photon appear to be at a higher frequency, since this is non-nonsensical we end up with the conclusion that each photon has a lowest frequency which is when the observer inhabits the frame it was created in, which is fine, but then the photon has a preferred (discoverable) frame! John On Sat, Mar 8, 2014 at 5:43 AM, David Roberson <[email protected]> wrote: > There has been a continuous discussion on the list about the reality of SR > time dilation and length contraction. Most of the commenters accept the > time dilation concept since it is relatively easy to measure. Some among > the group point out the paradox that they perceive as existing, but for now > I want divert attention to evidence of length contraction that seems highly > relevant. > > I found an article in Wikipedia about the free electron laser. There is a > technique for generating very high energy tunable x rays which strongly > depends upon the length contraction due to electron velocities near light > speed. The frequency and wavelength of the emitted radiation can be > directly calculated by using the Lorentz factor. Read the article found at > the following link: http://en.wikipedia.org/wiki/Free_electron_laser to > see how well the mathematics works. > > The process uses an alternating series of magnets that are clearly spaced > a large distance apart when compared to the the emitted wavelength of the > synchronous radiation. If you accept that the electrons are moving at very > nearly the speed of light, then the wavelength should be approximately > equal to the spacing between alternate magnets unless that distance is > effectively shortened by the Lorentz contraction as seen by the electrons > in motion. The shortening factor directly enters into the determination of > the radiation frequency. A radio wavelength structure of magnets is > employed to achieve an x-ray length emission due to Lorentz contraction. > > Harry, this might help to explain the behavior of your train on the track > questions. Think of the distance between the magnets as being similar to > the space between the rail ties. > > Dave > >
