Speed of Light: A universal Constant?
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From: The Ghost In The Machine on 2 Apr 2005 20:00 In sci.physics.relativity, H@..(Henri Wilson) <H@> wrote on Sat, 02 Apr 2005 23:21:50 GMT <f5au41p1m4h5pjacaresa5e6082hcuro8q(a)4ax.com>: > On Sat, 2 Apr 2005 12:45:15 +0000 (UTC), > bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote: > >>H@..(Henri Wilson) wrote in >>news:m7js41592c9au3a6sm78losoh02h5knpho(a)4ax.com: >> >>> Bz assumes the signals travel at the same speed through the (identical) >>> cables irrespective of their direction of travel. >>> >> >>I assume no such thing. >> >>First of all, the signals are traveling in ONLY ONE DIRECTION, from the >>detector to the oscilliscope. A quibble: I for one don't see exactly how to characterize this properly, but an AC signal at, say, 20,000 Hz will presumably wiggle the electrons through a spread of no longer than 15 km if the cable is long enough. >> >>I have signals from two different detectors >>I have those signals travel down different cables to my scope. >>I measure the difference in arrival time of the two signals >> >>I then swap the cables around so that signal 1 travels down cable 2 and >>signal 2 travels down cable 1, I will be able to accurately determine the >>difference in time between signal 1 and signal 2 by averaging the times. This would have to be done somewhat carefully as swapping the signals involves twisting the cables and/or changing (slightly) the delta-y (assuming the cables are parallel along the x-axis of a hypothetical coordinate system), leading to very minor issues. If we assume perfect cables under infinite tension (an impossibility, obviously!), lightspeed signal propagation, and a cable distance of 10 m and a separation of 1 cm, the cables would be required to lengthen by about 5 microns. The error in lightspeed measurement would therefore be 5 microns / 300,000 km/s = 1.67 * 10^-14 s, out of an approximate time measurement of 3.33 * 10^-8 s. This indicates a relative error of approximately 500 parts per billion. Rotating the equipment 180 degrees introduces issues as well, because of the Earth's gravitational field distorting space. If the equipment requires anything on the z-axis (which for this hypothetical experiment might be affected by gravity), inversion might change the measurement by a miniscule amount. If the equipment does not require anything on the z-axis inversion may be acceptable, and of course cables aren't under infinite tension anyway; the main issue is then the bending required by the 180 degree twist, and the effect that would have on the measurement -- which is probably even less than 500 parts per billion, though there might be minor issues with brehmsstrahlung. >> >>Have you ever used an oscilliscope? > > I was using CROs before you were born. > > You are a fool. You understand nothing about this subject. > > HOW DO YOU KNOW THAT THE SPEED OF YOUR SIGNALS IS NOT DEPENDENT > ON DIRECTION OF THE CABLES? > > TRY USING AN OPTIC FIBRE. Optical fibre would suffer the same signal-speed anisotropy as electrical cabling. That is not a solution. Of course, it turns out signal-speed anisotropy is not really a problem, either. :-) OLWS lightspeed is isotropic to a few parts per billion, if my memory is correct regarding certain experiments thereon. (My memory also tells me that the experiments did not measure OLWS directly.) [.sigsnip] -- #191, ewill3(a)earthlink.net It's still legal to go .sigless.
From: bz on 3 Apr 2005 00:55 The Ghost In The Machine <ewill(a)sirius.athghost7038suus.net> wrote in news:qsp3i2-88h.ln1(a)sirius.athghost7038suus.net: > In sci.physics.relativity, H@..(Henri Wilson) > <H@> > wrote > on Sat, 02 Apr 2005 23:21:50 GMT > <f5au41p1m4h5pjacaresa5e6082hcuro8q(a)4ax.com>: >> On Sat, 2 Apr 2005 12:45:15 +0000 (UTC), >> bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote: >> >>>H@..(Henri Wilson) wrote in >>>news:m7js41592c9au3a6sm78losoh02h5knpho(a)4ax.com: >>> >>>> Bz assumes the signals travel at the same speed through the >>>> (identical) cables irrespective of their direction of travel. >>>> >>> >>>I assume no such thing. >>> >>>First of all, the signals are traveling in ONLY ONE DIRECTION, from the >>>detector to the oscilliscope. > > A quibble: I for one don't see exactly how to characterize this > properly, but an AC signal at, say, 20,000 Hz will presumably wiggle > the electrons through a spread of no longer than 15 km if the cable > is long enough. Thanks for the analysis. I am sure you realize that the cable acts like a transmission line and will conduct pulses that contain much higher frequencies than 20kHz. Properly terminated transmission lines appear to be infinite in length as far as the signal is concerned. The main question is the loss factor and the cable length. Loss goes up with frequency. At 144 MHz some typical figures are [quote http://www.catfleet21.org/rigging/June.htm] Cable Diameter Loss Per Length Per Type (Inches) 100' 3 dB Loss RG-58 .195 6.1 dB 49' RG-8X .245 4.5 dB 66' RG-8U .410 2.7 dB 111' [unquote] This will affect the pulse hight and shape IF the cables were very long. I don't contemplate anywhere near 15 km. > >>> >>>I have signals from two different detectors >>>I have those signals travel down different cables to my scope. >>>I measure the difference in arrival time of the two signals >>> >>>I then swap the cables around so that signal 1 travels down cable 2 and >>>signal 2 travels down cable 1, I will be able to accurately determine >>>the difference in time between signal 1 and signal 2 by averaging the >>>times. > > This would have to be done somewhat carefully as swapping > the signals involves twisting the cables The cable runs would be carefully marked, the swap would mean disconnecting BNC connectors at each end of both cables and swapping their physical locations, reconnecting the BNC connectors. Any changes in cable dress would be very slight. > and/or changing > (slightly) the delta-y (assuming the cables are parallel During part of their runs they would probably be parallel. We might assume the cables are minimum length and the scope is located midway between the two detector, in which case the cables would NOT be parallel. We could make the cables as long as the distance between the detectors, in which case the system would look like an equalateral triangle. As long as the time delay for the signal propagation is [close to] identical in both cables, it should not matter how long the cables are, as long as the signal pulse can be detected and the rise time is identical in both. Swapping detectors as well as cables would eliminate possible rise time asymetry effects. > along the x-axis of a hypothetical coordinate system), > leading to very minor issues. If we assume perfect cables > under infinite tension (an impossibility, obviously!), Not sure why the coaxial cable transmission line needs to be under tension. My transmission lines are usually NOT under physical tension. > lightspeed signal propagation, and a cable distance of 10 > m and a separation of 1 cm, the cables would be required > to lengthen by about 5 microns. > The error in lightspeed > measurement would therefore be 5 microns / 300,000 km/s = > 1.67 * 10^-14 s, out of an approximate time measurement > of 3.33 * 10^-8 s. This indicates a relative error of > approximately 500 parts per billion. > > Rotating the equipment 180 degrees introduces issues I am not contemplating rotating the entire apparatus. Just the disk that has the LED mounted on it. > as > well, because of the Earth's gravitational field distorting > space. If the equipment requires anything on the z-axis > (which for this hypothetical experiment might be affected > by gravity), inversion might change the measurement by > a miniscule amount. If the equipment does not require > anything on the z-axis inversion may be acceptable, and > of course cables aren't under infinite tension anyway; the > main issue is then the bending required by the 180 degree > twist, No 180 degree twists are needed. > and the effect that would have on the measurement -- > which is probably even less than 500 parts per billion, > though there might be minor issues with brehmsstrahlung. ..... >> TRY USING AN OPTIC FIBRE. > > Optical fibre would suffer the same signal-speed anisotropy > as electrical cabling. That is not a solution. > > Of course, it turns out signal-speed anisotropy is not > really a problem, either. :-) OLWS lightspeed is isotropic > to a few parts per billion, if my memory is correct > regarding certain experiments thereon. (My memory also > tells me that the experiments did not measure OLWS directly.) -- 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: Henri Wilson on 3 Apr 2005 04:45 On Sun, 03 Apr 2005 01:00:07 GMT, The Ghost In The Machine <ewill(a)sirius.athghost7038suus.net> wrote: >In sci.physics.relativity, H@..(Henri Wilson) ><H@> > wrote >on Sat, 02 Apr 2005 23:21:50 GMT ><f5au41p1m4h5pjacaresa5e6082hcuro8q(a)4ax.com>: >> On Sat, 2 Apr 2005 12:45:15 +0000 (UTC), >> bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote: >> >>>H@..(Henri Wilson) wrote in >>>news:m7js41592c9au3a6sm78losoh02h5knpho(a)4ax.com: >>> >>>> Bz assumes the signals travel at the same speed through the (identical) >>>> cables irrespective of their direction of travel. >>>> >>> >>>I assume no such thing. >>> >>>First of all, the signals are traveling in ONLY ONE DIRECTION, from the >>>detector to the oscilliscope. > >A quibble: I for one don't see exactly how to characterize this >properly, but an AC signal at, say, 20,000 Hz will presumably wiggle >the electrons through a spread of no longer than 15 km if the cable >is long enough. > >>> >>>I have signals from two different detectors >>>I have those signals travel down different cables to my scope. >>>I measure the difference in arrival time of the two signals >>> >>>I then swap the cables around so that signal 1 travels down cable 2 and >>>signal 2 travels down cable 1, I will be able to accurately determine the >>>difference in time between signal 1 and signal 2 by averaging the times. > >This would have to be done somewhat carefully as swapping >the signals involves twisting the cables and/or changing >(slightly) the delta-y (assuming the cables are parallel >along the x-axis of a hypothetical coordinate system), >leading to very minor issues. If we assume perfect cables >under infinite tension (an impossibility, obviously!), >lightspeed signal propagation, and a cable distance of 10 >m and a separation of 1 cm, the cables would be required >to lengthen by about 5 microns. The error in lightspeed >measurement would therefore be 5 microns / 300,000 km/s = >1.67 * 10^-14 s, out of an approximate time measurement >of 3.33 * 10^-8 s. This indicates a relative error of >approximately 500 parts per billion. > >Rotating the equipment 180 degrees introduces issues as >well, because of the Earth's gravitational field distorting >space. If the equipment requires anything on the z-axis >(which for this hypothetical experiment might be affected >by gravity), inversion might change the measurement by >a miniscule amount. If the equipment does not require >anything on the z-axis inversion may be acceptable, and >of course cables aren't under infinite tension anyway; the >main issue is then the bending required by the 180 degree >twist, and the effect that would have on the measurement -- >which is probably even less than 500 parts per billion, >though there might be minor issues with brehmsstrahlung. > >>> >>>Have you ever used an oscilliscope? >> >> I was using CROs before you were born. >> >> You are a fool. You understand nothing about this subject. >> >> HOW DO YOU KNOW THAT THE SPEED OF YOUR SIGNALS IS NOT DEPENDENT >> ON DIRECTION OF THE CABLES? >> >> TRY USING AN OPTIC FIBRE. > >Optical fibre would suffer the same signal-speed anisotropy >as electrical cabling. That is not a solution. > >Of course, it turns out signal-speed anisotropy is not >really a problem, either. :-) OLWS lightspeed is isotropic >to a few parts per billion, if my memory is correct >regarding certain experiments thereon. (My memory also >tells me that the experiments did not measure OLWS directly.) Well Ghost, I was trying to keep that a secret It is true because light speed is source dependent. > >[.sigsnip] HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: Henri Wilson on 3 Apr 2005 05:15 On Sun, 3 Apr 2005 00:22:05 +0000 (UTC), bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote: >H@..(Henri Wilson) wrote in >news:f5au41p1m4h5pjacaresa5e6082hcuro8q(a)4ax.com: > >>>Have you ever used an oscilliscope? >> >> I was using CROs before you were born. > >Sorry Henry, I confused you with kenseto. I have asked him several times >the same question and he never answered it. I was born in 1945. >Are you sure you were using a CRO before I was born. It is very bad to have been born in 1945. Was your father a draft dodger? >I have been playing with electronics since I was 8. I built a scope when I >was 16. Got my ham license the same year. Tried to build a Ne laser in the >60's but couldn't get it to lase. Worked with YAG and CO2 lasers in the >70's while I was designing and building resistors and capacitors for >Sprague. But you still don't undestand why it is so haerd to measure OWLS. > >> >> You are a fool. You understand nothing about this subject. > >I understand that name calling is the refuge of those who have no good >arguments to make. All right, I will explain. The problem really stems from aether theory, of which SR is a subset. In aether theory, there is ONE absolute reference frame and light moves at c in all directions wrt that frame. It should not be difficult for you to see that if an observer is moving through that aether, his measurement of OWLS would be direction dependent and an indication of his absolute speed wrt that aether. But according to Lorenzt's ideas, the clocks and rods of a moving observer would change so that he would always get the answer 'c' for OWLS even if it wasn't true (or something like that). In your experiment, you have this setup: Light pulse->________D1_________CRO_________D2 When the pulse reaches D1, it sends an electrical pulse to the CRO via the cable. When it reaches D2, another electrical signal is sent to the CRO. It would be much more sensible to use a light signal rather than an electirc one and that is how this experiment is usually configured. You can see that in that case, the light signal from D1 reaches the CRO at the same time as the original light pulse. The pulse from D2, on the other hand is traveling in the oposite direction and you cannot assume it is traveling at the same speed. The time taken for each pulse might differ, even if the path lengths are identical. It is this very factor that you are trying to measure. > >> >> HOW DO YOU KNOW THAT THE SPEED OF YOUR SIGNALS IS NOT DEPENDENT ON >> DIRECTION OF THE CABLES? >> > >No need to shout. As for the direction of the cables, it doesnt matter. That is the whole point of the exercise....to prove that it is the same in both directions. > >> TRY USING AN OPTIC FIBRE. > >So that someone can say 'how do you know that the speed of your signals is >not dependent on the direction of the fiber optics?' > >Here is my suggest set up: >moving source of photons second > detector > >>-----------------------|-----------------------------| > << first > detector > >above is a diagram of the test set up. On the left is a disk that can be >spun. It has an LED at one point on the disk. In the center is a half >silvered mirror that deflects half the passing photons to a detector, >on the right is a second detector that detects the rest of the >photons. > >in between the LED and the first detector there are a couple of pin >holes to make sure that we only see photon that are emitted when the >LED is travelling straight toward the detectors. > >We are measuring time it takes the light to pass from the first >detector to the second detector. >We are using one clock to do this. >The light travels only one direction. >This is the one way speed of light. > >There is a coax cable from first detector to channel 1 of the scope >There is a coax cable from second detector to channel 2 of the scope > >These cables are identical in length and construction. TDR (time domain >reflectometer) shows them identical in length. > >First we trigger on channel 1 and measure time delay to signal on channel >2. Then we swap coax cables and trigger on channel 2 and measure time >delay to signal on channel 1. > >In each case we are measuring the time that it takes light to go from >first to second detector. Swapping cables shouldnt make any difference >because the cables are the same length. But if it does, we average the >times and correct for any extra delay in one cable. > >Then we spin the disk with the LED and measure the one way speed of light >from a moving source. We can do this with many different speeds, if we >want. You wouldn't have a hope. Do the sums. > >I am certain that I can show that the doppler shift is NOT due to changes in >the speed of the photons with this set up. kenseto keeps saying that I can't >measure the owls with the setup and talking about signals going both ways on >the coax cables, and talking about two clocks and the need to syncronize >them. I don't have two clocks. My cables are the same length. Ken is a dedicated aetehrist and is correct in what he says. Even SRians will assure you that two clocks are needed for an OWLS experiment. Both will argue that it is impossible to synch the separated clocks adequately. > >Tell me why I can't measure the one way speed of light with my set up. You think about it. In actual fact, according to the ballistic theory, it is perfectly easy to absolutely synch two separated clocks using Einstein's clock synch definition. If you don't understand that, you should read up on it because it underlies the whole theory. The main difficulty in measuring OWLS from a moving source is that the experiment must be carried out over huge distances and with source speeds around .001c. It is now just possible to do this. HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: bz on 3 Apr 2005 07:41
H@..(Henri Wilson) wrote in news:kibv411vh5nvp2rce21ts3l95ollnp5o0d@ 4ax.com: > It is very bad to have been born in 1945. It seems like a good year to me, not that I had any choice. > > Was your father a draft dodger? What a strange question. Why would such a question pop into anyones mind? He was a 1st Lt. in the Army. As for the light speed measurement, since my experiment is aimed at testing to see if the speed of the source (doppler shift) changes the speed of the photons; even if, as you say, I am not measuring the true OWLS, I am still measuring the speed of light and as there is no change in any of the distances involved as I change the speed of the source, my experiment should suffice to demonstrate that the speed of the source changes ONLY the wavelength of the photons. Thanks for the discussion and have the best of all possible days. -- 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 |