Speed of Light: A universal Constant?
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From: bz on 8 Apr 2005 09:03 RP <no_mail_no_spam(a)yahoo.com> wrote in news:s-udnaukW7_fksvfRVn- ug(a)centurytel.net: > Now here's another thought for the day. Suppose I have a very tight > laser beam, 850nm. If a spaceship is moving away from the source > sufficiently fast that wrt it the wavelength is 10 meters, then how is > it that I see the beam incident on an area of the ship of, oh, about > 1mm, while he sees it as completely enveloping him? Hmmm. How in the > hell does a 10meter beam focus to a spot 1mm diameter? Cool indeed, so > cool that I think I'll have to pass on it if you don't mind. :) > since the photons 'look like a point when seen "end on"', but like waves when seen from the side. By the way, in order for me to recieve that laser beam on 10 meters, you will have to put as many photons into it as a normal 10 meter transmission would have created. Lets say I can detect a .1 micro volt signal(a good receiver can do better than this) at 29.98 MHz (10 meters). That is about 2e-16 watts. I need a certain number of photons to detect your signal. Each 10 meter photon carries 2e-26 Joules. Each 850 nm (3.5e8 MHz) photon carries 2.3e-19 Joules. You are going to need to transmit with 1.1e7 times the power you would have needed to use to cover the same distance, had I not been moving. If a one watt would have covered the distance, were I not moving, you will need to transmit with 11,000,000 watts. -- 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: kenseto on 8 Apr 2005 08:59 "Sam Wormley" <swormley1(a)mchsi.com> wrote in message news:YRg5e.12636$g65.6136(a)attbi_s52... > kenseto wrote: > > > ROTFLOL....you and SR reject the notion of a light carrying medium and now > > you want to use the properties of a light medium to explain the diffraction > > phenomenon? > > Seto--I want you to read this http://scienceworld.wolfram.com/physics/Diffraction.html > and the associated links and references and tell us how diffraction requires a > medium! Hey idiot runt....PD uses water waves to explain the diffraction phenomenon for light. Since water waves are waves in the medium water so I naturally conclude that light must also have a medium to give the effect of water waves. Ken Seto > > Here's your chance to learn something, Seto! >
From: kenseto on 8 Apr 2005 09:13 "PD" <pdraper(a)yahoo.com> wrote in message news:1112907541.166733.303640(a)z14g2000cwz.googlegroups.com... > > kenseto wrote: > > "PD" <pdraper(a)yahoo.com> wrote in message > > news:1112887032.405849.87520(a)l41g2000cwc.googlegroups.com... > > > > > > kenseto wrote: > > > > "PD" <pdraper(a)yahoo.com> wrote in message > > > > news:1112798512.354764.174830(a)l41g2000cwc.googlegroups.com... > > > > > > > > > > kenseto wrote: > > > > > > "PD" <pdraper(a)yahoo.com> wrote in message > > > > > > news:1112731023.977565.318940(a)z14g2000cwz.googlegroups.com... > > > > > > > > > > > > > > Jim Greenfield wrote: > > > > > > > > The Ghost In The Machine > <ewill(a)sirius.athghost7038suus.net> > > > > > wrote in > > > > > > > message > news:<l9a9i2-f6i.ln1(a)sirius.athghost7038suus.net>... > > > > > > > > > In sci.physics, H@..(Henri Wilson) > > > > > > > > > <H@> > > > > > > > > > wrote > > > > > > > > > on Mon, 04 Apr 2005 21:31:29 GMT > > > > > > > > > <u6c351du1rm845dlvhj309smegtid0gnm9(a)4ax.com>: > > > > > > > > > > On Mon, 4 Apr 2005 12:09:32 +0000 (UTC), bz > > > > > > > <bz+sp(a)ch100-5.chem.lsu.edu> wrote: > > > > > > > > > > > > > > > > > > > >>H@..(Henri Wilson) wrote in > > > > > > > news:gh4251dpkork18r2kknvn2gu6lt979b8m3@ > > > > > > > > > >>4ax.com: > > > > > > > > > >> > > > > > > > > > >>> Ghost, is not velocity always specified relative to > > > > > something? > > > > > > > > > >>> > > > > > > > > > >>> Is not the speed of light always 'c' wrt its > source? > > > > > > > > > >>> > > > > > > > > > >>> > > > > > > > > > >> > > > > > > > > > >>The velocity of light is always c with respect to the > > > > > observer. > > > > > > > > > > > > > > > > > > > > Proof please! > > > > > > > > > > > > > > > > > > No proof available. At best, there are several > experiments > > > > > > > > > that show evidence for this statement, a number of > indirect > > > > > > > > > experiments that show evidence for related concepts, > and > > > > > > > > > a number of observations of astrophysical phenomena > that > > > > > > > > > show evidence for other related concepts given certain > > > > > > > > > assumptions. > > > > > > > > > > > > > > > > Primary assumption that has mired physics / astronomy for > > > decades > > > > > > > > being that > > > > > > > > Doppler is falsely attributed to a magical wavelength > > > alteration, > > > > > > > thus > > > > > > > > skewing > > > > > > > > many measurements as to distance, velocity and > composition > > > > > (spectra) > > > > > > > > > > > > > > And this shows you know nothing about how light's > wavelength is > > > > > > > measured. One approach that's been around for years is the > > > > > diffraction > > > > > > > grating. With a diffraction grating, light of a particular > > > > > wavelength > > > > > > > is scattered and shows constructive interference at an > angle > > > that > > > > > is a > > > > > > > function of the ratio of the light's wavelength and the > spacing > > > of > > > > > the > > > > > > > etching in the grating. Nothing else -- no c's, no > frequencies, > > > no > > > > > > > other buried physics -- just the ratio of the light's > > > wavelength to > > > > > the > > > > > > > spacing of the etching the grating, a ratio of two > distances. > > > > > > > > > > > > You are wrong. the observed fringe pattern is not due to > > > constructive > > > > > > interference. It is due to the absolute motion of the grating > wrt > > > the > > > > > light > > > > > > rays. See the explanation for the double-slit experiment in > my > > > > > > website.....click on to the section entitled "Past > Experiments > > > > > Detecting > > > > > > Absolute Motion" > > > > > > http://www.erinet.com/kenseto/book.html > > > > > > > > > > Uh-huh. And the observed fringe pattern that occurs with sound > > > waves or > > > > > water waves in a ripple tank, also using a diffraction grating, > is > > > also > > > > > not due to constructive interference, but is due to the > absolution > > > > > motion of the grating with respect to the sound or water waves? > > > > > > > > > > So light's wave behavior and observed wavelike phenomona, stem > from > > > > > completely different origins than what is seen in other wave > > > phenomena? > > > > > Is that really what you want to maintain? > > > > > > > > ROTFLOL....you and SR reject the notion of a light carrying > medium > > > and now > > > > you want to use the properties of a light medium to explain the > > > diffraction > > > > phenomenon? > > > > > > > > Ken Seto > > > > > > > > > Medium, schmedium. There is nothing in the explanation of > diffraction > > > and interference that is based on the presence of the medium, nor > on > > > the velocity of the wave transmission. > > > > You wer the one who uses water wave to explain the interference of > light. So > > are you backing off that assertion? > > Not at all. But the presence of the medium is not essential to the > interference in that case, either. The fact that there IS a medium with > a water wave is irrelevant. Then why did you use the properties of water wave to explain interference of light?? >Your argument is akin to saying that > gravity acting on an apple falling from a tree cannot be linked to > gravity acting on the moon, because the apple is surrounded by air and > the moon is not. The air is irrelevant to the force of gravity acting > on the apple. ROTFLOL....this is so stupid not worth commenting. Ken Seto > > Here's a visual "derivation" of interference: > http://galileoandeinstein.physics.virginia.edu/more_stuff/flashlets/youngexp t4.htm > Click Play, and then after a bit click Pause. Then click Show Path > Difference. The only thing that determines whether there is > constructive or destructive interference is the ratio of the path > difference to the wavelength. Note that there is NO mention of medium > in this derivation, nor is there any need of any velocity appearing in > that ratio -- only path difference and wavelength. > > > PD > > > > > >You are apparently unaware of > > > that explanation or the derivation of relationship between the > > > wavelength, diffraction grating spacing, and the angle of the > > > diffracted light, since you continue to insist that it depends on > > > things that do not pertain. > > > > All these are assertions. the correct interpretation is in my > website: > > http://www.erinet.com/kenseto/book.html > > > > Ken seto > > > > > > > > PD > > > >
From: George Dishman on 8 Apr 2005 09:48 "Henri Wilson" <H@..> wrote in message news:ajnb51dd873nu01pibt29747tlc58ahk04(a)4ax.com... > On Fri, 8 Apr 2005 00:20:38 +0100, "George Dishman" > <george(a)briar.demon.co.uk> > wrote: > >> >>"Henri Wilson" <H@..> wrote in message >>news:gvbb519mnbu1f2gkf04fe92nhkuhson1ui(a)4ax.com... >>> On 7 Apr 2005 05:43:16 -0700, "Dishman" <george(a)briar.demon.co.uk> >>> wrote: <snip all areas agreed> >>> I will also try to incorporate the c+v factor at the source and each >>> mirror. >> >>Think carefully about that. c+v from the source >>hitting a mirror moving at v means a relative >>incident speed of c, hence a reflected speed of >>c relative to the mirror or c+v in the lab frame >>again. > > Not so George. > You forget the mirrors rotate slightly as the light is traveling between > them. > So each mirror is moving at slightly off 90 deg wrt to the previous > one...... > that complicates the issue somewhat. Not so Henry, I have not forgotten that at all. I should add the mirror orientations at the time of reflection to make this clearer but if you check my applet, you will find the angles are such that the mirrors are not at 90 degrees except when the source and detector are co-located, i.e. the table is not moving. A subtle point: when you adjust the slider, it does not represent the speed of the table but the angle through which it will have turned when the light reaches the detector. Given the angle and the fact that the light of interest is that which reaches the detector, simple trig will calculate the path length. Divide that by the speed of light (whatever you choose) and that tells you the time of flight. Divide the angle by the time of flight and you get the table speed. The situation has been simplified by a number of assumptions we made, in particular that all the mirrors are at equal radius, all are perpendicular to a radius and the table turns at constant speed. The basic rule for the mirrors is of course that the angle of incidence equals the angle of reflection so a little geometry will show that each leg of the path plus the two end radii must form similar triangles. That means the legs take equal time so the table turns through equal angles, quarter of the total per leg in the case of three mirrors. Knowing that, it becomes easy to plot the path and you can then work back to speeds and times if you want. Trying to work forward is much harder. George
From: Sam Wormley on 8 Apr 2005 10:11
kenseto wrote: > > Hey idiot runt....PD uses water waves to explain the diffraction phenomenon > for light. Since water waves are waves in the medium water so I naturally > conclude that light must also have a medium to give the effect of water > waves. > Seto should learn http://dictionary.reference.com/search?q=analogy |