Speed of Light: A universal Constant?
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From: Bilge on 4 May 2005 13:49 bz: >dubious(a)radioactivex.lebesque-al.net (Bilge) wrote in >news:slrnd7d24q.7j2.dubious(a)radioactivex.lebesque-al.net: > >> bz: >> >dubious(a)radioactivex.lebesque-al.net (Bilge) wrote in >> >> >A simple op amp can square up the rise time on the pulses from the PM >> >tubes, if necessary. >> >> You can ``square up'' the signal that way, but the leading edge of >> the square pulse you create will not be suitable for a timing mark, >> since the position of the leading edge will depend upon the response >> of the op-amp to the rise-time of the input signal. I've exaggerated >> the scale, but this is the problem. >> >> Input: >> >> .. . . >> . . <- V_thresh --> . . >> . . . . >> >> | | >> t=0 t=0 >> >> Output: >> >> +--+ >> | | >> | | >> >> +--+ >> | | >> | | >> >> To obtain a decent timing signal that eliminates the rise-time >> dependence, > >So timing would really be dependent on pulse amplitude, right? >As we spin faster, pulses get narrower and have lower amplitude. This would >introduce a systematic bias. Right. More precisely, the timing depends upon the signal reaching some threshold value to generate a timing mark and the time it takes to reach that voltage depends upon the slope of signal. [...] >> >> If you're using a phototube, a 5mW laser will fry it. > >Thought I might start off with the power down a bit. >My original design was with an LED for a light source. :) Use the LED - preferably a blue one. Phototubes don't deal with bright light very well. Phototubes can see light at the level of single photons. The relevant specification is the quantum efficiency. For example, a quantum efficiency of 15% means that that, on average, 1 in 6 photons will produce a photoelectron. The gain can easily be a factor of 10^6, so blasting the photocathode with light is not a good idea. You might also look into PIN diodes, but those might not work at optical frequencies. I haven't checked. >Henri thought the pulses would be too weak to detect so I upped the power a >bit. Henry is batting a perfect 0.000. Just remember that you have a better chance of being right by flipping coin than by listening to henri. > >Yeah, I don't really care about the absolute time of flight, just relative, >as I change speed of the rotating source. You could also obtain twice the time difference by arranging to have light sources on opposite points of the wheel: -> [det] 0 -> [det] Using the scheme I drew earlier with the time-to-amplitude converter, what you'll get is a signal with an amplitude proprtional to the difference in the times the detectors are triggered. You don't need to null out the TAC, either and in fact, it's better if you don't. All you have to do is plot amplitude vs. velocity. Normally, one would run the TAC into an ADC and histogram the results.
From: bz on 4 May 2005 14:15 dubious(a)radioactivex.lebesque-al.net (Bilge) wrote in news:slrnd7i5h9.t2e.dubious(a)radioactivex.lebesque-al.net: > bz: > >dubious(a)radioactivex.lebesque-al.net (Bilge) wrote in > >news:slrnd7d24q.7j2.dubious(a)radioactivex.lebesque-al.net: > > > >> bz: > >> >dubious(a)radioactivex.lebesque-al.net (Bilge) wrote in > >> > >> >A simple op amp can square up the rise time on the pulses from the > >> >PM tubes, if necessary. > >> > >> You can ``square up'' the signal that way, but the leading edge of > >> the square pulse you create will not be suitable for a timing mark, > >> since the position of the leading edge will depend upon the response > >> of the op-amp to the rise-time of the input signal. I've exaggerated > >> the scale, but this is the problem. > >> > >> Input: > >> > >> .. . . > >> . . <- V_thresh --> . . > >> . . . . > >> > >> | | > >> t=0 t=0 > >> > >> Output: > >> > >> +--+ > >> | | > >> | | > >> > >> +--+ > >> | | > >> | | > >> > >> To obtain a decent timing signal that eliminates the rise-time > >> dependence, > > > >So timing would really be dependent on pulse amplitude, right? > >As we spin faster, pulses get narrower and have lower amplitude. This > >would introduce a systematic bias. > > > Right. More precisely, the timing depends upon the signal reaching > some threshold value to generate a timing mark and the time it takes > to reach that voltage depends upon the slope of signal. > > [...] > >> > >> If you're using a phototube, a 5mW laser will fry it. > > > >Thought I might start off with the power down a bit. > >My original design was with an LED for a light source. :) > > Use the LED - preferably a blue one. Phototubes don't deal with > bright light very well. Phototubes can see light at the level of > single photons. The relevant specification is the quantum efficiency. > For example, a quantum efficiency of 15% means that that, on average, > 1 in 6 photons will produce a photoelectron. The gain can easily > be a factor of 10^6, so blasting the photocathode with light is not > a good idea. You might also look into PIN diodes, but those might not > work at optical frequencies. I haven't checked. > > >Henri thought the pulses would be too weak to detect so I upped the > >power a bit. > > Henry is batting a perfect 0.000. Just remember that you have a better > chance of being right by flipping coin than by listening to henri. > > > > >Yeah, I don't really care about the absolute time of flight, just > >relative, as I change speed of the rotating source. > > You could also obtain twice the time difference by arranging to have > light sources on opposite points of the wheel: > > > -> [det] > 0 > -> [det] > I guess the two detectors can look down a tube toward the source so they don't see the other source. [or maybe use one detector] Henri suggested a similar experiment but he wants to use two mirrors. One source and one detector. I prefer moving the light sources and losing the factor of two due to the reflection. In both cases, I am not quite sure how the radial velocity as the light beams sweap across the detectors can be related to the time of flight of the photons. I am sure it can be done, but it seems SO much easier to just measure the time of flight between two points > > Using the scheme I drew earlier with the time-to-amplitude converter, > what you'll get is a signal with an amplitude proprtional to the > difference in the times the detectors are triggered. You don't > need to null out the TAC, either and in fact, it's better if > you don't. All you have to do is plot amplitude vs. velocity. > Normally, one would run the TAC into an ADC and histogram the > results. And wave the magic trig wand a bit. -- 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: Sue... on 4 May 2005 16:11 Just cause we love ya BZ Light explores all paths. http://farside.ph.utexas.edu/teaching/em1/lectures/node24.html http://spiff.rit.edu/classes/phys314/lectures/reste/reste.html http://www.physics.yorku.ca/undergrad_programme/highsch/Feynm4.html ------ Sue....
From: Henri Wilson on 4 May 2005 17:48 On Wed, 4 May 2005 10:08:08 +0000 (UTC), bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote: >H@..(Henri Wilson) wrote in >news:hdrg719ufum44asb0c92h0g90moh4d8nb7(a)4ax.com: > > >> Mass doesn't change with >> speed. That is obvious...nor does anything else. > >Now THAT is demonstrably false. A few minutes with a particle accelerator >will show you are wrong. Particles BEHAVE as though their mass becomes larger. But it doesn't. Particles become more difficult to accelerate as their speed increases wrt the accelerating fields. That is because the particles themselves surround themselves with a 'reverse field bubble' which reduces the effective 'driving field'. Not only that, it is probably that fields take time to operate. > >> Give a lump of rock a push and what happens? You increase its KE and its >> mass. > >> SR claims it gets heavier in half the frames in the universe and lighter >> in the other half. > >No. SR says that if you accelerate it[enough] wrt your frame of reference, >from rest wrt your frame of reference, you will observe an increase in >mass. 'observe?' > >SR says that if you (or the particle) are moving at high velocity wrt each >other and you match velocities, (slow the particle or speed yourself up) >then you will observe the particle has less mass. there you go. You prove my point. You agree that if I speed myself up the mass will appear to decrease. Obviously, my change in speed can have no effect on the mass itself. > >> So what is the obvious REAL answer. > >Reality is stranger than you think. SR is plain nonsense. >>>An optical illusion. >> >> More evidence of your indoctrination. > >I have an open mind. I do NOT have an emotional investment in SR. If it >falls, it falls. I will not be unhappy either way. That is not >indoctrination. You seem to have been blinded by the propaganda of hthe inbred physics establishment. >> They will try to wriggle out of anything that might disprove their >> 'religion'. > >There are times I wish I had faith in a theory. It would be so comforting >to live in a world of faith. Become a muslim then. > >>>>>Speed, spin (?), angular momentum, rest mass. Those are 'intrinsic' >>>>>properties. I don't know of any others. >>>> >>>> Bilgey will try to tell you that a photon is a point particle with no >>>> properties except energy. He claims all photons are identical. >>> >>>He could be right. Some say the same about electrons. >> >> Well what makes an electron an electron and not a photon? > >According to Wolff, it is the direction of the twist of the standing wave. An oversimplification. > >>> >>>Back when the earth was flat, anyone that thought it was round was an >>>idiot, right? >>> >>>It wasn't really flat? But everyone knew it was so it must have been. >>>(NOT) >> >> The trouble with SRians is that they think they have ALL the answers. >> They don't have any. >> >> I have made the point many times that physics has only scratched the >> surface when it comes to the really important questions. It is very >> primative. > >I don't know any scientist that are the kind of 'Srians' that you seem to >think exist. The scientists I know KNOW that they don't have all the >answers. They are always looking for data that will disprove theories. > >Finding data that would disprove SR is their quest. Such would be >publishable and revolutionary. > >You seem to think they have a reason to REJECT such data because it would >challenge their faith in SR. You only have to read the typical replies from the SRian lackeys we have on this NG. Half the time they don't even read the article. They condemn it out of principle. Their ultimate debating 'weapon' is the claim that '"you don't understand relativity". I can honestly say th I have never seen one original contribution from an SRian supporter here. All the controlled discussion and creative stuff comes from those of us who can see what is wrong with the theory > >Perhaps that is the way you approach science, but that is not the way >scientists approach science. You are obviously just starting out. You are in for a few rude shocks. Success in science depends on 1) who you know, 2) how good you are at writing up another person's ideas in a disguised way and 3) conforming to the views of the establishment. >>> >>>I can not assume WHAT? >>>That IF the concentration (mostly hydrogen in intersteller space) is 1 >>>molecule per cc, then the effect of traveling 1.4 million light years >>>would be the same as traveling through one meter of hydrogen at STP? >>> >>>On what basis do you challenge that assertion? Did I drop a decimal >>>place in my calculations? What is wrong with my 'IF...THEN'? >> >> Try doing the same with a cube of water molecules..... let the light >> arrive at an angle. > >A cube of water molecules [vapor]? >Why would I do that? The most common gas in interstellar space is >hydrogen, not water. > >Or do you mean a cube of liquid water? >Why would I do that? Water does not exist as a liquid in space. > >Your argument does not hold water. You are going to have to do better than >that if you want to challenge my 'IF...THEN'. I think my example showed perfectly well why you cannot make such assumptions. >>> >>>In science, one never proves anything. >>>If you are looking for proof, you are not a scientist. >> >> That is often claimed...very debatable. >> I think it is possible to prove things within certain axioms. > >Given certain assumptions, you can always 'prove' things. That is logic. >Logic is used in science. > >The job of science is to challenge the assumptions. > >> >> For instance it is pretty conclusively proved that lightning is caused >> by a flow of electric charge between clouds and the ground. > > >Scientists study lightning to understand it better. Your statement is >mostly observation, data, not a theory. > >However, the way you have stated it, it is wrong. Find the flaw in your >statement. I didn't go into details but the statement is basically correct. If charge DID NOT flow between clouds and ground there would be NO lightning. Agreed? > > >> The fact that we don't actually know what electricity is doesn't really >> matter. > >Oh it matters. We continue to try to find out what electricity is. that is an attempt to take the 'truth' to a higher level of 'proof'.. >>>> So does changing relative lightspeed. >>> >>>But changing relative lightspeed would populate our universe with >>>photons traveling at many different speeds. >> >> What's wrong with that? Stars and planets do it all the time. > >The thing that is wrong with it is that it is inconsistent with all our >observations. We have never observed a photon traveling in a vacuum at a >speed other than c, yet you would have almost all of them traveling at >different speeds. bz, how many times do I have to inform you that nobody has ever measured the OWLS of ANY photon. Are you inherently stubborn or just plain dumb? >>>>>Wrt its source. Wrt any target. >>>> >>>> Why should you think that. >>> >>>Because it is consistent with all observations. >> >> Bull. >> Nobody has ever measured it. > >No one has ever measured anything different. Lots of measurements have >been made. You claim that none count because they are not 'OWLS' >measurements. It tunrs out, according to the BaT, that for any TW light sl\peed experiment in which all components are at rest, OWLS = TWLS. TWLS is persistently measured via this type of experiment as having the value 'c' to high accuracy. That is even more evidence that the BaT is correct. >>>>>so m = (c^2 / sqrt(1 - v^2/c^2))/E >>>> >>>> The term 'gamma' is a myth based on Einstein's erroneous assumption >>>> that a vertical light beam in one frame becomes a diagonal beam in >>>> another. >>> >>>Are you on the level? Give me your slant on the subject. >>> >>>> >>>> My demo: www.users.bigpond.com/hewn/movingframe.exe shows why. >>> >>>I looked at it. >>> >>>It makes perfect sense to me that photons look different from different >>>reference frames. Their direction of travel looks different and their >>>energy looks different. >> >> What makes the green photons move at a different speed from the purple >> laser ones. > >Your program. My program simlates what happens....plain and simple. SR is based on a quite obvious fallacy that stemmed directly from aether theory. > >> SR is nonsense. It is rehashed aether theory. > >Even if it were, that is not the insult that you seem to think it is. > >> It claims that a vertical beam in one frame appears diagonal in another >> that is moving. However when you point a laser at that same angle in the >> moving frame, its photons clearly don't move at the same speed. > >I doubt that you have been able to make such an observation in reality. I don't have to. The stupidity of SR's very foundations are obvious. > >Your program does what you tell it to do. The photons don't care about >your program. So all the simulations used to desing engineering marvels don't work, either? > > >>>I also looked at the electron traveling wave picture. Why did you pick >>>that number of cycles? >> >> Just an illustration....not a quantitative example at all. > >I suspect that a photon is only one cycle. You suspect..... 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 4 May 2005 17:54
On Wed, 4 May 2005 18:15:22 +0000 (UTC), bz <bz+sp(a)ch100-5.chem.lsu.edu> wrote: >dubious(a)radioactivex.lebesque-al.net (Bilge) wrote in >news:slrnd7i5h9.t2e.dubious(a)radioactivex.lebesque-al.net: >> >Henri thought the pulses would be too weak to detect so I upped the >> >power a bit. >> >> Henry is batting a perfect 0.000. Just remember that you have a better >> chance of being right by flipping coin than by listening to henri. >> >> > >> >Yeah, I don't really care about the absolute time of flight, just >> >relative, as I change speed of the rotating source. >> >> You could also obtain twice the time difference by arranging to have >> light sources on opposite points of the wheel: >> >> >> -> [det] >> 0 >> -> [det] >> > >I guess the two detectors can look down a tube toward the source so they >don't see the other source. [or maybe use one detector] > >Henri suggested a similar experiment but he wants to use two mirrors. One >source and one detector. Note how Bilgey gets his good ideas from me. > >I prefer moving the light sources and losing the factor of two due to the >reflection. > >In both cases, I am not quite sure how the radial velocity as the light >beams sweap across the detectors can be related to the time of flight of >the photons. I am sure it can be done, but it seems SO much easier to just >measure the time of flight between two points It isn't. > Incidentally, bz, you seem to have missed my improved experiment that requires no CROs or expensive photodetectors. Here it is again: I have now devised an ingenious way of performing this experiment without the need for an expensive photodetector or CRO. Distance can be reduced to 300 metres or less. It uses my configuration with two mirror facing opposite ways on a rotating wheel. |m \m3 O S | |plate o |m shield As the wheel spins, light is reflected from the laser source back towards an observer, o, who is positioned behind an etched glass plate. A shield is positioned between this plate and the wheel to prevent direct light impinging on the plate. A third mirror is placed just in front and slightly to one side of this plate. During the experiment, this mirror is arranged to spin exactly in synch with the wheel. It is phased so that each reflected flash is deflected onto the optical plate and at the same time considerably narrowed. Thus, two reflected pulses that are NOT traveling at the same speed will NOT illuminate the same point on the plate. Instead the observer will see two bands of light, the separation between which should increase with rotation speed. Since the operation is continuous, the amount of energy striking the plate should be sufficient to be observed easily, if not visually then for instance with a line of cheap photodetectors. Synchronization of the mirror3 with the wheel can be achieved using a frequency source midway between them. 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. |