Speed of Light: A universal Constant?
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From: bz on 12 Apr 2005 04:07 The Ghost In The Machine <ewill(a)sirius.athghost7038suus.net> wrote in news:e5sri2-jfv.ln1(a)sirius.athghost7038suus.net: > In sci.physics, bz > <bz+sp(a)ch100-5.chem.lsu.edu> > wrote > on Tue, 12 Apr 2005 02:17:20 +0000 (UTC) > <Xns9635D890BE10AWQAHBGMXSZHVspammote(a)130.39.198.139>: >> H@..(Henri Wilson) wrote in >> news:583m51h8hhu0g8ajo90b41hkplnu33b21m(a)4ax.com: >> >>> On Mon, 11 Apr 2005 14:33:40 +0000 (UTC), bz >>> <bz+sp(a)ch100-5.chem.lsu.edu> wrote: >>> >>>>H@..(Henri Wilson) wrote in >>>>news:crgk51phu180c3v483f93pfgaeccvl9dlt(a)4ax.com: >>>> >>> >>>>>> >>>>>>Once the photon has been detected and converted to electric impulses >>>>>>traveling down the scope leads, we need not fear that some >>>>>>mysterious effect will nullify any effect due changes in the speed >>>>>>of light. You are not going to tell me that the electronical impulse >>>>>>travel at different speeds down the wire and THAT speed is dependent >>>>>>on the speed of the photons that generated the impulse, are you?? >>>>> >>>>> Listen idiot, you know nothing about physics. Do a few calculations >>>>> and you will see that your 'experiment'; is totally useless. >>>>> >>>> >>>>worlds fastest oscilloscope [circa 2002] had 6GHz bandwidth, 20GHz >>>>sampling rate. http://www.engineeringtalk.com/news/tek/tek129.html >>>>6 GHz is 1e-10 seconds. >>>> >>>>a 10000m/s doppler shift, if it changed the speed of the photons, >>>>would result in a 3.33e-5 shift in speed. >>> >>> What the hell are you trying to say. Doppler shift doesn't 'cause' a >>> light speed change. You have it back to front. >> >> I don't think that the velocity of the source changes the velocity of >> the photons. I don't think that doppler shift changes the speed of >> light. > > The issue is easy to calculate if one can budge gamma enough. > > If one has a spinning disk with edge velocity v towards > the OWLS measurement device as you propose, the energy of > each photon, which presumably can be easily measured by > some sort of applied-voltage electron liberation detector > (taking advantage of Einstein's photoelectric effect), > would be expressible as a ratio as follows: > > BaT: (c+v)^2/c^2 > SR: 1/sqrt(1-v^2/c^2) > > For v << c SR predicts an amount roughly 1/4th the amount > of BaT, and should easily be detectable, given known v > and known laser characteristics. right. > > One minor problem with the spinning disk is that GR gets > involved, slowing down time for the laser. This may > double the effect, somehow -- but that's still only > 1/2 of BaT. > > Another minor problem is that photons from the spinning > disk will spray all over the place. :-) You probably want some kind of housing around the disk, anyway, for safty, with a hole for the light to exit in the desired direction. > > This may also be done in tandem with a long lighttube and another > identical (except that it's stationary) laser diode, setting up > a "race condition". Perhaps. Hard to get identical frequency and phase. A variable speed motor is enough, for the purpose of this experiment. > It's a pity we cannot use the moon (the > detectors aren't sensitive enough to pick up the returning > photons from a spinning laser diode, throwing rays at the moon). Not unless we used some humongous laser diodes! Of course we could just run the experiment ON the moon. > However, if we can resolve things to the nearest picosecond We can. > and > have an edge velocity of 300 m/s, we can use a mirrorless lighttube > of length 1 microsecond -- about 300 m. Right! > (It has to be mirrorless, > mostly so that one cannot ask the dumb question "but what if the > mirrors are treated as light re-emitters?". :-) Ideally it would > be evacuated and cooled to below the temperature of liquid air > as well Cool! But in this case, I suspect it would be overkill. > -- and of course it has to be arrow-straight.) Right. Has to be laser straight. > > SR of course predicts a null result; BaT predicts a differential > of about 1 picosecond. Should be relatively easy. Of course cyclotrons have light emitters that are moving at much higher velocities. If the velocity of the photon was influenced by the velocity of the source, I suspect that the effect would have already been detected. I imagine that some 'time of flight' experiments have already been run on such photons. -- 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 12 Apr 2005 05:35 "N:dlzc D:aol T:com \(dlzc\)" <N: dlzc1 D:cox T:net(a)nospam.com> wrote in news:tHH6e.6720$EX4.4837(a)fed1read01: > Dear bz: > > "bz" <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message > news:Xns9634AF3039C6CWQAHBGMXSZHVspammote(a)130.39.198.139... >> "N:dlzc D:aol T:com \(dlzc\)" <N: dlzc1 D:cox T:net(a)nospam.com> >> wrote in >> news:wIf6e.6563$EX4.3962(a)fed1read01: ..... >> I know it was indiscrete of me, but I couldn't resist the pun. > > ;>) I hung up those spurs a long time ago... :) >>>> All of the quantities can be measured under >>>> certain circumstances. >>> >>> I disagree. The ones I claim are model >>> dependent are inferred from observation, >>> not the result of direct observation. >> >> Diffraction gatings infer the wavelength > > Correct. You need slit geometry, distance from detector to > slits, and a *model* to get wavelength. > >> while photo-electric ejected >> photons are direct observables? > > Yes. Current flow (or lack thereof) indicates cutoff. I see a Model here too. > >> Momentum is observable? > > Yes. A change in state of an orbital electron... > Definitely a model here. >> I don't think ANY of them are DIRECTLY >> observable. We infer there is quantification, >> momentum, energy, frequency, and >> wavelength from the effects. > > Frequency and wavelength are *much* further from being an > observable. I think something is coloring your outlook on the situation. >> I don't know of ANY direct way to measure >> any of them. The diffraction grating is the >> closest to a direct measure of any of them, >> AFAIK. Emission, absorbtion spectra give >> us information from which we can calculate >> energy and infer quantification. > > You can think of many ways to measure energy (bolometer for one). Models, one and all. > A radiometer (if tiny enough, and truly evacuated) can get close > to measuring momentum. Once again a model sits in the middle. ..... >> >> I don't think ALL polarizers rotate the plane >> of polarization. > > They all do, if they select polarization. Just as all light > mediums affect a c_medium < c if light is transmitted. Maybe polaroid filters take plane polarized light and make it slightly eliptical, IF the plane of polarization is not co-incident. > >> For example, reflections from non metalic >> surfaces tend to be plane polarized, so you >> can use such reflections to polarize a beam. > > All reflection is in fact absorption and re-emission. Sounds like a model to me. > >> Icelandspar separates photons based on >> polarization as does calcite. > > But they do this during *transmission* where the medium already > moderates a great deal of what happens to the light. agreed. ..... >>> So "information" belongs to the host? Is >>> "wavelength" information? >> >> wavelength, phase, path, many other things >> are all information. > > But not the blow of a fist (a single photon absoption, to be less > cryptic)? That requires "context" to convey information, right? Understanding requires context. ..... >>> Water waves can exactly cancel at such an >>> interface. >> >> but only at certain points, on the wave fronts. > > anechoic chambers. Think again. Divide and conquer... Divide and absorb. Build a pseudo anechoic chamber with reflective surfaces and you divide but do NOT conquer. ..... >>> Self-interference simply shows >>> quantum behavior, not wave behavior. >> >> This is easy to believe when we talk >> about visible light. It is harder to swallow >> when we talk about 10 meters RF. Yet >> they are both part of the same continuum. > > Agreed. But the size of the laboratory necessary to express all > the same effects for 10m RF is what I call "provincial thinking". > Imagine you had eternity, and all the money in the world, you > could duplicate for 1Hz, what you can to for THz, right? > My grant proposal for a 1 Hz MMX device was turned down. .... >> Host? > > The multitude. The population (or a statistically significant > sample thereof). AH... I thought you were talking about the Mass. ..... >>> Only the model >>> provides the wavelength. >> >> I can measure the wavelength of a 440 MHz >> transmitter (0.68 meters, 2.9e-25 Joules) with a >> section of HO guage MODEL train track and a >> 6 volt dial lamp by measuring the distance >> between voltage peaks on the standing wave. >> So, in a way I am using a model, but it sure >> looks like a direct measurement to me. I >> realize I am working with many photons in >> this case. > > Can't do this very will with infrared. But then, provincial > thinking... > > By the way, how does this method of "direct measurement" of > wavelength handle c_medium in the conductor of the train track The velocity factor of open wire feed line is well known. http://www.astrosurf.org/lombry/qsl-transmission-line.htm > , > and how do you know you have a half- or quarter- wave or full > wave? The open end of the line is a high impedence point. The next point of max voltage is 1/2 wave from the open end. The next point of max voltage is 2/2 waves from the open end, etc. > Are you *sure* you don't need a model to get to > wavelength? I usually use a light bulb. I take the model off the track before I use it to measure wavelength. :) And you are right, there is a model. There are models involved in everything. We each carry our own model of the world around in our mind. ..... >>> Does a photon change because I am moving >>> wrt the source of the photons? >> >> That depends on whether or not we are looking >> at the photon from your framework or the >> sources frame work or my framework. >> >> As someone pointed out to me, if a 10 meter >> transmitter was sending a signal, and you >> were approaching at a high velocity so that >> the 10 meter signal was doppler shifted >> enought, it would knock electrons from your >> photocathode. > > And are the photons different, or is my detector different? Neither. The interaction between them is different. Long photons explain this kind of interaction better. The rate of change of the E and B fields is faster because the moving detector 'sees' it change faster. ..... >>> MMX performed in a frame (using visible >>> light in that frame) that has a gamma of >>> 1000 wrt to you, has done this experiment. >>> They can also do the rotating drum >>> experiment, and they will find no different >>> results than you do. They will find the size >>> of the photon, photons you will decide are >>> "too long", to be inclusive of zero size too. >> >> They will measure different sizes than I will >> [for the same photons]. > > They will measure size "inclusive of zero", to within the > precision of measurement. The laws of physics don't change... "inclusive of zero" is due to limitations of the experiment. [quote] The invariant mass Wýýý can sometimes be well measured, if all the final state particles are caught by the detector. But in multihadron final states some of the particles are often missed, which means that both Wýýý and the Bjorken scaling variable ... will be badly measured, and biased. There is no alternative way of determining Wýýý from the initial state kinematics, as can be done for Wýýp in electron-proton scattering at HERA, because both virtual ýýs are drawn from broad bremsstrahlung-like spectra. [unquote] Inclusive of zero doesn't mean 'must be zero'. ..... >> perhaps I am provincial. > > We all are. Our common sense is raised on lack. > ... >>>> I see no reason to doubt that frequency and >>>> wavelength also apply to individual members >>>> of the population. >>> >>> The *model* that invokes these terms can be >>> applied. It has no meaning to an individual >>> member. >> >> But it CAN be applied? >> It does have meaning to me. > > The answer is no. The reason is that a model involving knowing > more about a single particle than can be known is involved. You > can claim your credit limit is the national average, but it > doesn't mean it is so. The national dept does influence my credit limit. ..... >> It may require I readjust my model [when it >> fails to describe what happens]. >> It doesn't do anything to photons behavior. > > So at least yoru eyes are open. Good. > >>>> I don't think that a photon, when >>>> separated from the crowd, behaves >>>> differently than it did in the crowd. >>> >>> I am not claiming that they do. I am >>> claiming it is like applying "median >>> age" to describe a first-grader. It is >>> meaningless at that level to do so. >> >> Not if you are a year younger than the >> median age. > > Tell little Timmy he is median age in his first grade class. Little Timmy is over 2 sigma from the median age as he is repeating the class. >>>>> Experimentally, this is the case. An electron >>>>> is "demoted" or "promoted" (as far as we can >>>>> tell) instantly between bound states (or >>>>> unbound states). A photon is very much like >>>>> an impulse function. >>>> >>>> There is apparently a small delay, unlike >>>> stimulated emission. >>> >>> There is NO delay. Classically it is >>> expected, experimentally there is no delay. >> >> Then speed transiting a media should be >> equal to c, since the speed between >> absorbtion/emission is c. > > The duration is between absoprtion and re-emission. *That* is a > function of the medium. You're calling it a 'duration'. I am calling it a 'delay'. ..... >> how? Where is the delay centered? What >> causes the delay? > > Permittivity and permeability. In the medium. Finding the right > "place" to release the absobed momentum. If the place is the important point, then the delay will vary but there should be no scattering. If the time is important [or at least the half life] then there should be scattering. Perhaps BOTH mechanisms occur, to varying degrees, depending on the medium. >>>> Right. The small delay mentioned above. >>> >>> And contrary to your "finite photon length" >>> model, the delay is longer for shorter >>> wavelengths. >> >> That is a problem, but doesn't quite defeat >> me yet. More thinking is called for. > > OK. Just do a little research on the index of refraction for > different wavelengths. We have higher energy [pressure], it takes LONGER to store all of it in a vessel--when the filling/emptying must take place through a critical oriface. [A critical oriface is a flow limiting device. Once the pressure is above a certain value, the flow rate is constant and independent of pressure.] ..... .... >>>> How does it know what the frequency/energy/ >>>> wavelength is going to be? >>> >>> The charge is accelerated. The acceleration >>> describes the emission. >> >> When does the emission take place. How does >> the photon know what energy it carries. > > Only two "things" attribute energy to a photon. The emitter, and > the absorber. Given that transmission mediums also (briefly) > absorb... The photon neither knows nor cares. .... >>> How did you resolve this, by the way? .... > I meant "nuts and bolts". Was it a faulty component, and bird on > the wire, or what? Do you remember, or do you use a hand grenade > like I do ("fix" a lot of things hoping on of them will do it). The tuning of the transmitter had been incorrect. The antenna was a random length of wire. I really don't remember the exact details now. This was in 1961. I will have to dig out my log books and see if the details are there. .... >>>>> There is some emission associated with >>>>> cable length to antenna tip. >>>> >>>> Most of the emission comes from the >>>> bottom 1/3 of the antenna. >>> >>> Makes sense, since current flow near the >>> tip is always "near zero", so is >>> acceleration of charge there. Funny how >>> the sweet spot on a bat is 1/3 of the way >>> down from the tip... >> >> For not too disimilar reasons, I suspect. > > Ever corked an antenna? ;>) You can 'base load' an antenna, or center load it. This lets you resonant the antenna at a longer wave length by adding a lumped inductance rather than using distributed inductance. ..... > So what do you think of "broadcast power"? Not sure if you have > any interest in Nikola Tesla, but: > URL:http://www.abelian.demon.co.uk/tesla-notes/030802.html > ... giant microwave? Interesting article. Still reading it. Apparently Tesla was wrong about some things. Would be nice if 'Broadcast power' really worked. -- 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: Dishman on 12 Apr 2005 08:37 Henri Wilson wrote: > On Mon, 11 Apr 2005 20:33:31 +0100, "George Dishman" <george(a)briar.demon.co.uk> > wrote: > > > > >"Henri Wilson" <H@..> wrote in message > >news:3e7j51pufhl884iav96einhf6ee09n7aq0(a)4ax.com... > >> On Sun, 10 Apr 2005 10:37:46 +0100, "George Dishman" > >> <george(a)briar.demon.co.uk> > >> wrote: > >>>"Henri Wilson" <H@..> wrote in message > >>>news:o7lg51h09o1qrva29p3mqp5r5prdacbq0j(a)4ax.com... > >>>> On Sat, 9 Apr 2005 08:53:31 +0100, "George Dishman" > >> > >>>> Yes that works nicely. > >>>> > >>>> It shows the standard explanation of ring gyros. It appears > >>>> on the surface to be perfectly sound. > >>> > >>>Then help me here Henri, I'm puzzled. You clearly > >>>understand my explanation, it's nothing new as you > >>>say, but a few posts back you said: > >>> > >>>>> I cannot see that any theory other than some kind of > >>>>> 'local aether' one can account for this. > >>>>> > >>>>> SR certainly doesn't and I cannot yet see how it fits > >>>>> in with the ballistic theory. > >>> > >>>The description I have illustrated is basic SR, > >>>the speed of the light in the lab frame is c, so > >>>what do you mean when you say SR doesn't explain > >>>the effect? > >> > >> I cannot see any connection with SR. > > > >I think it is obvious. The the speed of the light > >is c in the lab frame, a simple deduction from > >the postulates of SR. To emphasise the point, > >consider two such experimental setups in the same > >lab. One is fixed to the floor while the other > >moves through the lab on rails at constant speed. > >My analysis holds good for both because the speed > >is c in an inertial (non-rotating) frame > >referenced to the centre point of _either_ table. > > But you don't know if the number of fringes moved is the same in both cases for > the same rotation! > > To show that you will have to move one setup at a very high speed. Hold on Henri, let's finish the point before looking at another. We were discussing the basis of the explanation I gave, not experimental results. That can come later. You said that you couldn't see the connection between the standard explanation as shown in my animation and SR. The link is that it uses the fact that the speed of light is the same in all inertial frames to determine the behaviour of the light. Do you now follow that part? You also said: > >> It is based on an aether concept that > >> there is an absolute frame. That is not true because the spee would be c in the aether frame in that case. Do you see that? Here are the details: > >Whether some other aether-based theory might look > >similar is irrelevant, the explanation is valid > >for an SR analysis. > > > >That said, you should also note that what I posted > >is _not_ a valid analysis for most absolute frame > >theories where the speed of light is c in that > >frame and you have to consider the speed of the > >lab with respect to the preferred-frame to find > >the speed of the light at any point. > > > >The simplest example might be a Galilean aether > >with the lab moving through the aether in a > >directon that lies in the plane of the turntable. > >The speed of the light when moving round the table > >in the same direction as the lab is moving wrt. > >the aether is c-V while on the other side of the > >table is it c+V. Of course this mostly cancels out > >as both beams traverse almost one full turn but > >the beam going the same way as the table rotation > >covers the section between the emission point and > >where it hits the detector twice while the other > >beam never travels that part. The result is that > >the speed in that section varies depending on the > >alignment of that part with the direction of > >aether flow and as it varies slightly round the > >table, there would be a slight modulation of the > >signal with orientation. That would be tiny and > >unmeasurable in reality but it is there > >theoretically. Clearly that is a quite different > >approach and a slightly different result. > > > >With a Lorentz-invariant aether, we know it gives > >the same results as SR so it could borrow the > >analysis I gave. Still, from first principles, you > >should start as I did for the Galilean aether to > >find the speed at any point round the path but > >taking account of length contraction which turns > >the table into an ellipse instead of a circle. > >Then note that the frequency of the light emitted > >will be altered by the Lorentzian equivalent of > >"time dilation" depending on the speed of the > >source through the aether at the time of emission. > >Then find the phase difference between the delayed > >version of this that reaches the detector by the > >two paths. > > > >I'll say good luck if you want to try that > >approach, I don't like the look of it at all, but > >it must end up giving the same result as SR. > > > >Anyway, the point is that any preferred-frame > >analysis must take account of the motion of the > >table centre in the preferred-frame and that > >factor does not appear in what we have done so > >far so you cannot mistake the analysis for an > >absolute-frame theory, and as I said at the top, > >even if some aether theory did by chance coincide, > >it doesn't prevent this being a valid SR analysis. > > It might be an analysis but is it correct? The SR one certainly is. It has been around for over 90 years, ever since Sagnac did the experiment, and has been examined by hundreds of students and experimeners. It has been peer reviewed more times than you and I have had hot dinners! The aether analyses above are just outlines to make the point that they would have to take the speed of the lab wrt the aether into account hence my analysis is obviously not aether-based. f you now understand those points and can see that my animation is SR-based, we can move on. > >>>> I accept that rotation CAN be detected absolutely but I don't > >>>> agree with that explanation because it ignores the fact that > >>>> light is actually being internallyreflected an infinite number > >>>> of times by and infinitesimal amount. > >>> > >>>That is dealt with by the more thorough analysis > >>>that shows the effect is proportional to the area > >>>eclosed by the light path. See for example this > >>>page where it is calculated for an arbitrary > >>>polynomial after the circular version: > >>> > >>>http://www.mathpages.com/rr/s2-07/2-07.htm > >>> > >>>> I only want to analyse the four mirror system. Your demo > >>>> would have to consider a few other factors then. > >>> > >>>Ok, but you will need to tell me what other > >>>factors you want to consider. AFAIK, we have > >>>covered all the areas of uncertainty you > >>>brought up last time and eliminated any effect > >>>from them. > >> > >> Incidentally, in a ring gyro, is a hollow fibre used or a solid one? > > > >Solid, follow the link to the e-core material on > >the KVH site. Those I have seen so far have used > >internal reflection rather than graded index but > >much of the technical spec. for the materials is > >over my head. > > > >BTW, I haven't mentioned refractive index as I > >assumed you would realise it cancels out in both > >theories. > > Does it? I'll have to think about that. The easy way is again in the rotating frame. Both beams move at c/n instead of c in the Ritzian analysis so acts like a scaling factor on the output. The SR version would be more complex but it can be treated as a drag (ref. Fresnel's experiments with water in u-tubes) so would again produce just a scale factor. > It certainly complicates the animation. If you are doing the version with mirrors, just assume the apparatus is in vacuum. > Mine is well uinderr way...but is going to take some time. > My apparatus will have arms that are 1 light second long to make the effect > more apparent. OK. I'm looking forward to seeing it. > >It is actually one of the nice feaures of using > >these devices as a test of Ritz because any > >thoughts of the speed changing due to interaction > >with the air in the lab in the normal experiment > >is removed since the fibre rotates with the > >table. I know you dislike thinking in the table > >frame but when you realise there are no moving > >parts at all when viewed that way yet the speed > >of the light appears to change, I think it > >brings home the problem for Ritz. Centrifugal > >force on the photons is the only thing that could > >have an effect and that applies equally to both > >paths. > > I think there is a lot more to this. The standard explanation > is 'inadequate'. The standard SR explanation covers all it needs to. If you think something is missed, say what it is because nobody else has spotted it in 90 years, you could be famous ;-) For your Ritzian model, as I say, I have been waiting several years for someone to resolve the problem and I haven't seen any credible suggestions of what might be missed. Still, perhaps you will be the one to solve the problem. > ><snip> > >>>What did you have in mind, something like the > >>>circular one but with the wavefronts moving > >>>along the straight paths of the previous > >>>static beam diagram? That would take some time > >>>and I'm not sure it would prove much. The key > >>>I suspect is what extra you want to take into > >>>account. > >> > >> In the four mirror system, the light is reflected at an > >> angle that is not 90 (during rotation) > > > >The angles are illustrated in the simple path- > >drawing applet but it doesn't affect the time > >taken along the path so there is nothing to > >put into the animation. > > It DOES affect the time. Why do you claim it doesn't? Because the time is determined fully by the length of the path. Unless you are suggesting some sort of delay due to absorption and subsequent re-emission during the reflection process, I don't see how it can add anything to the path-length time. > >> There is also a quite complex velocity change to consider > >> at each reflection. > > > >No, we covered that last year. In SR of course the > >speed is c on each leg of the path regardless of > >the speed of the mirror. In Ritz, it could be more > >complex as there is a difference between a model > >involving absorbtion and re-emission versus a > >billiard-ball model, both of which could be > >compatible with the basic concept of ballistic > >primary emission. However, for paths that are a > >regular polygon, the symmetry means that the light > >approaches each mirror at c relative to the mirror > >so the question becomes moot, both models say the > >reflected light will move away from the mirror at > >c. Remember this? > > > >http://www.briar.demon.co.uk/Henri/speed.gif > > I don't understand that diagram. > > Why are the green lines sloping? The purple and green lines are the vectors, not the path of the light. The actual path is the red line and the sloping green line shows the direction the light must be emitted such that it adds to the motion of the mirror (shown by the purple vector arrow) to produce the resultant motion necessary for it to hit the second mirror. It is doing standard vector addition graphically, nothing fancy. > I will use the non-rotating frame in my animation.. OK, as long as you use the rule of reflection there shouldn't be any problem. We can use huygens to resolve any disputes. > >So again there is nothing to add to the animation. > > > >Can you think of any other possibilities? I have > >asked about half a dozen Ritz supporters including > >yourself over about six years and so far nobody > >has found anything I have missed. I guess you haven't spotted anything else yet. George
From: "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox on 12 Apr 2005 09:22 Dear bz: "bz" <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message news:Xns96362ECB28843WQAHBGMXSZHVspammote(a)130.39.198.139... > "N:dlzc D:aol T:com \(dlzc\)" <N: dlzc1 D:cox T:net(a)nospam.com> > wrote in > news:tHH6e.6720$EX4.4837(a)fed1read01: > >> Dear bz: >> >> "bz" <bz+sp(a)ch100-5.chem.lsu.edu> wrote in message >> news:Xns9634AF3039C6CWQAHBGMXSZHVspammote(a)130.39.198.139... >>> "N:dlzc D:aol T:com \(dlzc\)" <N: dlzc1 D:cox >>> T:net(a)nospam.com> >>> wrote in >>> news:wIf6e.6563$EX4.3962(a)fed1read01: > .... >>> I know it was indiscrete of me, but I couldn't resist the >>> pun. >> >> ;>) I hung up those spurs a long time ago... > > :) > >>>>> All of the quantities can be measured under >>>>> certain circumstances. >>>> >>>> I disagree. The ones I claim are model >>>> dependent are inferred from observation, >>>> not the result of direct observation. >>> >>> Diffraction gatings infer the wavelength >> >> Correct. You need slit geometry, distance >> from detector to slits, and a *model* to >> get wavelength. >> >>> while photo-electric ejected >>> photons are direct observables? >> >> Yes. Current flow (or lack thereof) >> indicates cutoff. > > I see a Model here too. Photoelectric current flow is proportional to intensity. Photoelectric bias voltage establishes energy of individual members (note that voltage has units of work). A LOT less model than inferring wavelength from a diffraction pattern. >>> Momentum is observable? >> >> Yes. A change in state of an orbital electron... > > Definitely a model here. But not with a radiometer. An atom could be a "radiometer vane". >>> I don't think ANY of them are DIRECTLY >>> observable. We infer there is quantification, >>> momentum, energy, frequency, and >>> wavelength from the effects. >> >> Frequency and wavelength are *much* >> further from being an observable. > > I think something is coloring your > outlook on the situation. Lets see: wavelength inference requires at least three measurements. bias or cutoff voltage requires 1. Who is wearing rose colored glasses? >>> I don't know of ANY direct way to measure >>> any of them. The diffraction grating is the >>> closest to a direct measure of any of them, >>> AFAIK. Emission, absorbtion spectra give >>> us information from which we can calculate >>> energy and infer quantification. >> >> You can think of many ways to measure energy (bolometer for >> one). > > Models, one and all. > >> A radiometer (if tiny enough, and truly evacuated) can get >> close >> to measuring momentum. > > Once again a model sits in the middle. Look, reality is moderated by our models. We don't get direct access to reality. The wave model requires more meausrements to infer wavelength, than the photoelectric emission model requires to get photon energy. You are getting hung up in minutae. >>> I don't think ALL polarizers rotate the plane >>> of polarization. >> >> They all do, if they select polarization. Just >> as all light mediums affect a c_medium < c >> if light is transmitted. > > Maybe polaroid filters take plane polarized > light and make it slightly eliptical, IF the plane > of polarization is not co-incident. Do your experiment. You'll find a filter alters all light that it polarizes. >>> For example, reflections from non metalic >>> surfaces tend to be plane polarized, so you >>> can use such reflections to polarize a beam. >> >> All reflection is in fact absorption and re-emission. > > Sounds like a model to me. OK. Done. David A. Smith
From: bz on 12 Apr 2005 11:14
"N:dlzc D:aol T:com \(dlzc\)" <N: dlzc1 D:cox T:net(a)nospam.com> wrote in news:iYP6e.6759$EX4.644(a)fed1read01: >>>> I don't think ALL polarizers rotate the plane >>>> of polarization. >>> >>> They all do, if they select polarization. Just >>> as all light mediums affect a c_medium < c >>> if light is transmitted. >> >> Maybe polaroid filters take plane polarized >> light and make it slightly eliptical, IF the plane >> of polarization is not co-incident. > > Do your experiment. You'll find a filter alters all light that > it polarizes. > I just sliced some segments off the edge of my polaroid sun glasses. IF I start with white light, from a white LED (shows no intensity varisation due to changes in polarization in the output light, when viewed through one filter.) The 'three filter experiment' 'works' as advertised. when I use my laser pointer, which is plane polarized [I can get a good null with one filter]; >>>--------filter1------filter2 o o o o o If filter 2 is adjusted for null output without filter 1 in place, THEN putting filter1 in place and rotating it through all possible orientations does NOT cause 'significant' output from filter 2. It does appears to rotate the null by a small amount, about 5 degrees, at most, but this is independent of the orientation of filter1 and is most likely due to the plastic carrier that surrounds the actual polaroid material. It would be nice to repeat the experiment with better polarizers, and with other kinds, such as icelandspar, but, to a first approximation, I would say that your contention is NOT supported by my experiment. Second experiment: Light reflected at the brewster angle from a surface is e-horizontally polarized. http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polar.html#c2 there is nothing to indicate that the polarization is rotated. e-horizontal light reflects, other angles of polarization pass into the material. So when I orient my pointer at the right angle and have the e-field vertical I get no reflection from the surface. Polaroid sun glasses are designed to absorb e-horizontal light when worn normally. A '45 degree incident angle' reflection experiment, using the surface of the gatoraid in the clear container on my desk. When the laser pointer is oriented for minimum reflection intensity, the polarization is orthogonal to the minimum intensity orientation of polaroid sunglasses, as normally worn. -- 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 |