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Link to thread of next article. Re: Do we sing in phase? Date: 1998/09/07
In article <6t03ah$unj$1@glencoe.hw.ac.uk> b.h.jarvis@hw.ac.uk writes: > When a singer subconsciously hits the right note, alongside the backing, > is it a sort of phase-lock loop happening? Does the singer end up in > phase with the note-giver, and remain "coherent"? > > I cannot believe that instruments played by hand and mouth could be > brought into phase, merely to the same note, so I am asking about the > human voice.
My guess is that for two singers, singing very nearly the same note they would phase lock if the coupling were strong enough. Maybe if both singers mouth's were inches from each other you might record an effect with an accurate microphone? Seems as phase lock should be a function of coupling strength and the difference in frequency?
Re: Do we sing in phase? Date: 1998/09/08
In article <6t13ri$307$5@supernews.com> "Mark Folsom" <folsomman@redshift.com> writes:
> As mentioned by Roy Everett, the frequency matching is probably not perfect
That is the whole point, the frequencies of the two oscillators do not have to be exactly the same if there is a coupling between them for them to phase lock. Granted, for the case being considered the coupling may be too weak for an effect even if the frequencies are very close and the coupling is maximum. But then, as the frequencies cross each other there should be momentary "phase drag".
Who was the scientist who noticed that two pendulum clocks on the same flimsy shelf kept the exact same time? Read it in an article in Scientific American. In this case you have two oscillators each with slowly varying phase but when coupled to each other are phase locked.
> so phase matching probably isn't remotely likely, even without the problems > I raised.
Maybe.
Re: Do we sing in phase? Date: 1998/09/08
In article <6t2c1d$1j3s@r02n01.cac.psu.edu> ale2@NOSPAMpsu.edu (ale2) writes:
> Who was the scientist who noticed that two pendulum clocks on > the same flimsy shelf kept the exact same time? Read it in an > article in Scientific American.
No you did not! You read something in Science News, April 13, 1996 vol. 14, page 236-237 and the article by Ivars Peterson was titled "Keeping the Beat". From page 236:
"Late in the winter of 1665, an ailing Christiaan Huygens was confined to his room for a few days. The Dutch physicist whiled away the hours of his confinement by closely observing and pondering the remarkable behavior of two pendulum clocks he had recently constructed. Huygens noticed that the pendulums of the two suspended clocks, hanging side by side from a common support, were swing in perfect synchronic. When one pendulum swung to the left, the other went to the right. The pendulums remained precisely in opposite phase for as long as he cared to watch. His curiosity piqued, Huygens began to experiment. ..."
Variations of the game Paper, Scissors, Rock? Date: 1998/09/16
Do you know of any interesting variations of the game Paper, Scissors, Rock played between two people?
How about this game between two people, the game of Even or Odd. Two players decide who will be even and who will be odd. Each player then makes a fist and on the count of three both players display 0,1,2,3,4, or 5 fingers. The sum is either even or odd. Score a point for odd if the sum is odd or a point for even if the sum is even.
This must be played by math students world wide?
Does the universe play a game like this at each point in spacetime?
Electrons viewed from a merry-go-round? Date: 1998/09/16
At the center of a merry-go-round an apparatus (at rest wrt the merry-go-round) contains an electron in a spin state that is just as likely to be spin up as spin down.
? Will a person riding on the merry-go-round and making measurements on such a state still find it to be an equal mixture of spin up and spin down? My guess is they will not based on classical reasoning. An object at rest (at rest wrt the merry-go-round) and at the center of a merry-go-round will appear to be spinning to a person riding on the merry-go-round.
I can find the transformations for spinors in different frames just not spinning frames. Any help or suggestions would be greatly welcome!
Link to thread of next article. Each particle "connected" to the other 10^80 in our universe? Date: 1998/09/16
In what sense, if any , is each particle in the universe connected to the other 10^80 particles in our universe?
I picture the 10^80 point particles with a string (or a pair of strings) (or other objects) running from all pairs of the 10^80 particles (and then maybe letting the point particles get fuzzy). I know this idea sucks but maybe it is a foundation upon which to build, ..., nah! %^(
See:
An overview of the transactional interpretation of quantum mechanics. by John G. Cramer, Internation Journal of Theoretical Physics, Vol. 27, No. 2 1988
and by the same author:
The transactional interpretation of quantum mechanics, in Reviews of Modern Physics, Vol. 58, No 3, July 1986
Re: Each particle "connected" to the other 10^80 in our universe? Author: Barbara Messner <barmess@mediaone.net> Date: 1998/09/17Forum: sci.physics.particle
ale2 wrote in message <6touti$pra@r02n01.cac.psu.edu>... >In what sense, if any , is each particle in the universe >connected to the other 10^80 particles in our universe? > >I picture the 10^80 point particles with a string (or a pair of >strings) (or other objects) running from all pairs of the 10^80 > The distance r of the line between each pair of charged particles, gives the potential energy V = +/- 13.6ev/r. r is in angstroms. This is by classical mechanics and also quantum mechanics. The Virial theorem and sawf say that the kinetic energy of the pair is T = -1/2 V. The sum of the energy Eij = Tij + Vij for all pairs is the eigenvalue of the eigenstate of the universe and is the total energy of the universe except for composite neutral particles such as photons, neutrons, neutrinos, etc.
Jim Goodman
Link to thread of next article. Where is the noise when I tune to a FM station. Date: 1998/09/26
My radio was on and tuned to a local FM station before it turned on. There was noise that went away as soon as ( presumably) the transmitter was turned on but nothing was being broadcast (but the carrier signal). Why did the radio get silent all of a sudden? Does it have anything to do with some kind of automatic gain?
Link to thread of next article. Ever notice this effect while singing to your computer? Date: 1998/10/06
While my computer was coming to life I let out a loud yawn while looking at my lit up computer screen (Macintosh Classic, B&W screen, 40 meg HD, 4meg RAM). An interesting (to me) effect was observed, the output of the computer screen appeared to be modulated in brightness in the following manner. What I saw were about 14 alternating horizontal bands of over brightness and under brightness. Hope that makes sense.
My curiosity somewhat aroused, I was able to quickly reproduce the effect by "singing" (humming) to my computer. It was found (using an electronic piano for calibration) that a frequency of about 495(?) Hertz (the B note above middle C) produced a maximum effect and at such a frequency there were about 7 darkish and about 7 lightish horizontal bands.
Thinking at first that my singing was effecting the computer I called my wife to look at the computer while I "sung". She could not see what I did, but when she sung along with me (and by herself), in perfect harmony, see could see the effect.
By humming at a low frequency and slowly raising the frequency one could get the bands to move up, stop, and then shift down the screen. Also this process would change the number of bands observed.
If one plays with the numbers 495 and 7 one finds that 496/7=70.71... or roughly 60 Hertz. Question, what is the vertical sweep rate on a Macintosh.
Did you ever notice this?
Link to thread of next article. References to the scattering of light off light experiment? Date: 1998/10/18 Anyone know of a reference to the experimental observation of the scattering of light off light? Jackson talks about the process but gives no reference to actual experimental results.
Has it been observed, the scattering of light off light? Date: 1998/11/12
Sorry for this repost.
My copy of Sakurai (Advanced QM, 1987) says that the cross section for light to scatter off of light is 4x10E-31cm^2 for roughly half MeV photons, which he states is too small to be observed experimentally.
Has anything changed in 13 years? Has light been observed to scatter off light (at any wavelength)?
Roughly how should the scattering cross section change as a function of photon energy? For example, what should be the cross section for visible light to scatter off visible light?
I am only interested in any process where charged matter is not present.
Re: Has it been observed, the scattering of light off light? Date: 1998/11/19
In article <72vic3$683$1@pravda.ucr.edu> baez@galaxy.ucr.edu (john baez) writes:
> Eh? The electron beam only serves to produce photons at GeV energies.
And these photons then go on to scatter off of the laser via electron positron pair production, but what is important to me is what is the distance from the point the virtual gamma photon is produced by the high energy electron to the point where the virtual gamma photon goes on to produce a virtual electron positron pair.
> There is no charged matter - except for *virtual* particles - involved > in the actual scattering process. In this process, the photons at GeV > energies scatter off the photons in a laser beam. Presumably they do > this by the following sort of process, which is the process everyone > talks about when discussing light-on-light scattering: > > ~~~~~------~~~~~~ > | | > | | > ~~~~-------~~~~~~ > > The wiggles are photons and the straight lines form a loop of > virtual charged particles, e.g. electron/positrons. (Draw arrows > going around the loop.)
ale2 wrote
> >The idea that all charged particles are somehow > >"connected" to each other and that the electromagnetic field is > >just a disturbance of these connections seems to forbid such > >photon photon scattering when no matter is present. > > I don't really understand this remark, which is a bit vague [....]
It was a bit vague so I could get past the overly wrong clause of sci.physics.research charter, if its vague how can it be wrong? %^)
The idea is: suppose each charged electron (considered as a point particle) is "connected" to every proton (each proton considered as a group of three point particles, quarks) in the universe. It makes an interesting picture even if completely incorrect, take the roughly 10^80 electrons and protons of the universe and make connections between each pair:
electron_i proton_j i, j = 1 to 10^80
Let the connections be very fine sewing string for concreteness. Also imagine that particles are then places where strings come or go and photons are somehow disturbances in these strings.
> and seems to contradict your previous sentence. Anyway, there > doesn't need to be any actual matter around; *virtual* particles > are sufficient, and virtual particles are everywhere.
Virtual particles are everywhere, but in some sense without matter present you would never know? Every experimental result which involves virtual particles in calculations also has matter (fields) present. I would question you as to why you feel so sure of these virtual particles "actually" being everywhere (only because I would learn something %^). What experiments involve virtual particles far from matter?
ale2 wrote
> >And to date > >I don't think any photons have been observed to directly scatter > >off of other photons (the interaction "far" from other charged > >matter). > > The above experiment is, I believe, the recent famous experiment > in which photon-photon scattering was observed. This is as good > as it gets. You can argue the semantics of what "far" from other > charged matter means, but the point is, we have a Feynman diagram > with only photons coming in, and only photons with different momenta > coming out.
Yes but again, how "virtual" is the gamma photon produced from the electron beam laser beam interaction.
Thanks for your thoughts!
I'm also looking for a Devil's advocate, any of you for hire %^)
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