Speed of Light: A universal Constant?
in [Relativity]
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From: bz on 26 Apr 2005 21:02 jgreen(a)seol.net.au (Jim Greenfield) wrote in news:e7b5cc5d.0504261558.5dfdc8c2(a)posting.google.com: > bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message > news:<Xns96314A7BC2DA3WQAHBGMXSZHVspammote(a)130.39.198.139>... >> jgreen(a)seol.net.au (Jim Greenfield) wrote in >> news:e7b5cc5d.0504062211.6957dcb5(a)posting.google.com: >> >> > ertain crystals emmit light of a fixed frequency. What is the >> > chemical reaction within the crystal, which causes it to alter its >> > emmitted wavelength, according as to how it is observed??? >> > Hint: the wavelength emmitted by the crystal does NOT alter from its >> > point of view; the Doppler shift noted by the observer is due to the >> > change in VELOCITY. >> > >> >> The relative velocity between source and observer. >> NOT the velocity of the photons. > > DHR's claim c invariant > c= fu > We know u is invariant, because the ruby does NOT change into a > sapphire. > We know that SOMETHING changes due to the motion, as we observe the > doppler. > A little grade seven algebra tells YOU, and even Wormey, that in a > three part equation, when one changes (in this case f) then another > MUST change----- > it is NOT u because the ruby remained a ruby, so it IIIIIISSSSSSSSSS > c!!!!!!!!! Buy yourself a police lidar. stand by the road and take the doppler speed reading of an approaching car. ride in a car and take the doppler speed reading of an approaching sign. ride in a car and take the doppler speed reading of an approaching car. stand by the road, have someone with the lidar ride in a car and YOU measure the doppler shift of the lidar as it approaches you. In all cases, the lidar frequency remains a constant, as far as the lidar is concerned. In all cases, the results are consistent with the lidar photons traveling at a constant speed of c with relation to the source, with relation to the detector and with relation to any observers. The shifts in frequency/wavelenght observed are simply due to changes in distance between source and detector as the waves are being emitted and detected. If you have sufficiently sensitive equipment to measure the time-of-flight of the photons from the lidar, you will find that it does NOT change as the speed of the source or detector changes. Or try it with sound. Buy yourself a tone generator. Radio shack sells some small tone generators. Turn it on. Put it on the end of a string. Have someone swing it around their head. You will hear the tone change as it approaches and goes away from you. The tone generator frequency is not changing. Swing it around YOUR head so that it maintains a constant distance from one of your ears. That ear will hear a constant tone. The doppler shift in sound is due to changes in distance between source and detector, NOT ballistic changes in the speed of sound. You can mount the tone generator on a spinning wheel, you can use a pulse generator to turn on and off the tone generator at a specific point during the rotation of the wheel. You can position a couple of microphones at different distances from the source. You can observe the transit time between mike 1 and mike 2. You will find it is independent of the rotation speed of the tone source. If you look at the wavelength/frequency of the tone detected by the microphones, you will see that it DOES change with the speed. Both sound and light travel through specific media at constant speeds irrespective of the speed of the source or detector. -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. bz+sp(a)ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
From: bz on 26 Apr 2005 21:06 H@..(Henri Wilson) wrote in news:klmt619ss22uufd5eeffv4kgeivds3ji1q(a)4ax.com: > There is not one iota of evidence that light from distant stars is ever > traveling at c wrt planet Earth. Why the hell should it? > There is not one iota of evidence that light from any source travels at a speed different from c with respect to source, detector or any other observer, in a vacuum. > Are you one of those religious cranks who still believes that Earth is > the focal point of the universe? No. Buy yourself a police lidar. stand by the road and take the doppler speed reading of an approaching car. ride in a car and take the doppler speed reading of an approaching sign. ride in a car and take the doppler speed reading of an approaching car. stand by the road, have someone with the lidar ride in a car and YOU measure the doppler shift of the lidar as it approaches you. In all cases, the lidar frequency remains a constant, as far as the lidar is concerned. In all cases, the results are consistent with the lidar photons traveling at a constant speed of c with relation to the source, with relation to the detector and with relation to any observers. The shifts in frequency/wavelenght observed are simply due to changes in distance between source and detector as the waves are being emitted and detected. If you have sufficiently sensitive equipment to measure the time-of-flight of the photons from the lidar, you will find that it does NOT change as the speed of the source or detector changes. Or try it with sound. Buy yourself a tone generator. Radio shack sells some small tone generators. Turn it on. Put it on the end of a string. Have someone swing it around their head. You will hear the tone change as it approaches and goes away from you. The tone generator frequency is not changing. Swing it around YOUR head so that it maintains a constant distance from one of your ears. That ear will hear a constant tone. The doppler shift in sound is due to changes in distance between source and detector, NOT ballistic changes in the speed of sound. You can mount the tone generator on a spinning wheel, you can use a pulse generator to turn on and off the tone generator at a specific point during the rotation of the wheel. You can position a couple of microphones at different distances from the source. You can observe the transit time between mike 1 and mike 2. You will find it is independent of the rotation speed of the tone source. If you look at the wavelength/frequency of the tone detected by the microphones, you will see that it DOES change with the speed. Both sound and light travel through specific media at constant speeds irrespective of the speed of the source or detector. -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. bz+nanae(a)ch100-5.chem.lsu.edu
From: bz on 26 Apr 2005 21:18 jgreen(a)seol.net.au (Jim Greenfield) wrote in news:e7b5cc5d.0504261624.556d6a17(a)posting.google.com: > bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message > news:<Xns9631E0BE0500FWQAHBGMXSZHVspammote(a)130.39.198.139>... >> jgreen(a)seol.net.au (Jim Greenfield) wrote in >> news:e7b5cc5d.0504071818.32282c6b(a)posting.google.com: >> >> > bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message >> > news:<Xns96314B27BA908WQAHBGMXSZHVspammote(a)130.39.198.139>... >> >> jgreen(a)seol.net.au (Jim Greenfield) wrote in >> >> news:e7b5cc5d.0504062211.6957dcb5(a)posting.google.com: ..... >> > >> > Any that produces a "fixed" signal. >> > I assume that you agree with Paul D, in that film records the rate of >> > impingement of light waves (sic photons). >> >> Nope. The film responds to the ENERGY of the photon. > > *********See below >> >> > We agree that the wavelength emitted by the crystal doesn't alter. >> >> agreed. >> >> > By the simplist algebra, that leaves only ONE possibility for the >> > motion of the crystal ref the source showing a different colour on >> > the film-- >> > "c" in c=fu has CHANGED >> >> nope. the relative velocity has added changed the >> frequency/energy/wavelength that the film sees. > > ****** Above we have the claim that the photon's energy has been > changed by the motion of the reciever (lol), and here the converse, > although the "relative velocity" is obviously between the film and the > photon; NOT the film and the SOURCE of the photon the relative velocity between source and detector influences the detected energy of the photon. The relative velocity between source and photon is c The relative velocity between detector and photon is c The ENERGY/frequency/wavelength is dependent on the relative velocity between source and detector. >> >> >> >> >> What makes you think it will not exhibit the color that would be >> >> represented by the doppler shifted emission? Said doppler shift >> >> being due to relative velocity of source and film. > > So HOW did the photon's ENERGY change???????????? > Hint: because it is going FASTER! no, because the alternations in E and M field are passing more rapidly but the photon itself is traveling at c. Picture the photon as a ~ traveling ----> If the source is moving ---> when the photon is emitted, the photon will be compressed along its axis of travel. But it still travels at the same speed. If the detector is moving toward the source, the photon is encountered in a compressed form and again, its frequency/energy is higher and the wavelength is shorter. It is still travling at c with respect to source, c with respect to detector and c with respect to any observers. Each may see a different frequency/enery/wavelength, however. >> > >> > Nope! As above, this should read "relative velocity of PHOTONS and >> > film." >> >> the relative velocity of photons and film is c. >> Do you think the dopplar shift in sound is due to changes in the speed >> of sound? > > And do you think that the propagation of a pressure front through a > gas has ANYTHING to do with photons traversing a vacuum?? Yes, both phenomina involve a wave like energy that travels at a constant velocity through the media in question. Both display doppler shifts. Neither changes velocity with the velocity of the source. -- bz please pardon my infinite ignorance, the set-of-things-I-do-not-know is an infinite set. bz+sp(a)ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
From: "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox on 26 Apr 2005 22:19 Dear G: "G" <gehan(a)dialog.lk> wrote in message news:1114496604.017531.211310(a)g14g2000cwa.googlegroups.com... > David > > So basically in laymans terms we can say the > speed of light is s/t where s is the distance > between source and target and t is the time > between elapsed between switching on the > light source and the illumination of the target? > (all in the same frame) No. The speed of light is an established contant. By convention, it is a fixed value. The time is the measurement. The distance is the inference. > I thought the metre was defined in terms of > wavelenght It was from ~1963 until 1983. Wavelengths (and counters) are still used to measure things very accurately. But not "correctly". David A. Smith
From: G on 26 Apr 2005 23:48
Henri But given the sameness (if we can assume it I think its called Isotropy) or constant expansion of the universe we can assume that the average for a subset of the stars of the universe will be close to the average for the entire universe, corrected for galalctive expansion.Surely there must be someone with the data and brains to do this sort of calucation. At NASA maybe? G |