Ballistic Theory, Progress report...Suitable for 5yo Kids
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From: bz on 2 Aug 2005 06:14 H@..(Henri Wilson) wrote in news:158te1ht09p39ckuj8amqdj5d6fo0rovbf(a)4ax.com: > Why don't you just accept that neither you nor anyone else has much of a > clue about light. Agreed. -- 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 2 Aug 2005 06:20 H@..(Henri Wilson) wrote in news:mc8te1p1jcju71a65e4t4q6nmn3abr170d(a)4ax.com: > On Mon, 1 Aug 2005 21:42:57 +0000 (UTC), bz <bz+sp(a)ch100-5.chem.lsu.edu> > wrote: > >>"Paul B. Andersen" <paul.b.andersen(a)deletethishia.no> wrote in >>news:dcm17g$9u5$1(a)dolly.uninett.no: >> >>> bz wrote: >>>> "Jeff Root" <jeff5(a)freemars.org> wrote in >>>> news:1122862205.456748.163740 @g44g2000cwa.googlegroups.com: >>>> >>>> >>>>>George replied to Bob: >>>>> >>>>> >>>>>>>The spectra seem to indicate that the single photons >>>>>>>have very narrow bandwidth [as I would expect]. >>>>>> >>>>>>If a photon has a specific energy and that is >>>>>>proportional to frequency, then a single photon >>>>>>has a unique frequency hence zero bandwidth and >>>>>>infinite duration >:-( >>>>>> >>>>>>At least it does with a semi-classical view. >>>>>> >>>>>>If you include Heisenberg, then the uncertainty >>>>>>in the measured energy relates to the uncertainty >>>>>>in the frequency which depends on the time over >>>>>>which the frequency is measured, hence the >>>>>>bandwidth is related to the method of measurement, >>>>>>and I don't need to point out the crucial role of >>>>>>measurement methods in QM. >>>>>> >>>>>>As a result, I don't think a photon has a specific >>>>>>length or duration, but the idea of it as a single >>>>>>cycle with hard ends at the zero crossings can be >>>>>>ruled out as too simplistic. >>>>> >>>>>The notion that a single photon can have a bandwidth seems >>>>>absurd to me. For reasons analogous to the notion that the >>>>>North Pole can have a longitude. It seems obvious that the >>>>>property of bandwidth only applies to statistical collections >>>>>of photons, or waves. >>>>> >>>>>I'm not sure it makes sense to talk about the frequency of a >>>>>single photon, either. Any photon has a particular, measurable >>>>>energy which is associated with a particular frequency, but >>>>>there is no way to measure that frequency. Only by analyzing >>>>>the behavior of a collection of photons does the property of >>>>>frequency become evident. The analysis shows that f = E/h, >>>>>so you can *know* the frequency of a single photon within the >>>>>limits of uncertainty, but you can't actually measure it. >>>>> >>>>>If you have enough photons to directly measure their frequency, >>>>>then you have enough photons to detect their bandwidth. >>>>> >>>> >>>> >>>> The question is 'how big'[long] is a photon. >>>> >>>> I can't see any reason that it should be more than one cycle in >>>> length. >>> >>> It doesn't make much sense to talk about the "length" of a photon. >>> A photon is a point particle. >> >>Something can be a point when seen from one direction and still have >>duration (length) along another axis. >> >>>> There is a paper >>>> http://jchemed.chem.wisc.edu/JCEWWW/Articles/DynaPub/DynaPub.html#ref1 >>>> 6 That I disagree with. They appear to believe that each photon >>>> consist of a wavetrain that is millions of cycles long. >>> >>> Remember that a "photon" is the particle aspect of the wave-particle >>> duality. >> >>A photon is the name we have given to the smallest possible 'bundle' of >>EM energy. In some experiments it looks like a wave, in some, it looks >>like a particle. Limitiations of our testing equipment. >> >>Some equations treat it like a wave, some like a probability function, >>some like a particle. >> >>None [that I know of] encompass all the photons observed properties. >> >>> It is true that you can make a classical (according to Maxwell) >>> "EM wave packet" which is limited in time and space, and which has >>> the energy of one photon. According to Fourier this "wave packet" >>> must have a certain relationship between the width of the spectrum >>> (spread of frequencies) and the extension in space. >>> The narrower the spectrum, the longer in space, and vice versa. >> >>I understand FT and FFT, modulation and what information theory says >>'must' happen. >> >>> But you cannot equate this wave packet to a photon - a particle. >>> You must consider it to be a probability function. >>> The width of the spectrum is then the uncertainty in the frequency >>> and thus the energy of the photon, and the extension in space >>> is the uncertainty in time (since the wave packet is propagating >>> the spatial extension can be interpreted as an uncertainty in time). >> >>I agree. I think there is an uncertainly in time for single photons. A >>small fraction of the time of one wavelength, a small phase uncertainty, >>should suffice. >> >>> The relationship mentioned above is thus in accordance >>> with the uncertainty principle. >>> >>>> Their theory seems to be falsified by femtosecond laser pulses. >>>> There are some that would be less than 2 cycles at the frequency of >>>> the laser. Also, the max keying speed of ELF transmission would seem >>>> to preclude any requirement for millions of cycled per photon. >>> >>> Quite. >>> If the pulses are very short and determined with high precision >>> in time (very short wave packet), the uncertainty in energy >>> must be high (Wave packet with very wide frequency spectrum.) >> >>Or there must be some uncertainly in the exact time the photon was >>emitted by the transmitting antenna. >> >>> But I will repeat: >>> It doesn't make sense to talk about the length of a photon. >> >>It would make an interesting experiment, if I had the equipment to do >>switching at zero crossing and sent 1 cycle at 160 meters [the 1.8 MHz >>amateur band], I think I should create a bunch of 160 meter photons. >>They would probably be spread out a bit in time. >> >>> Consider this: >>> We observe the H-alpha line from a very weak astronomical >>> source. With modern CCDs, we can literally count the photons >>> as they arrive, maybe only a very few photons per second. >> >>yes. >> >>> If we use a spectrometer, we can see that the spread in >>> frequency/energy is very small (it's a spectral line). >> >>yes. >> >>> But you can say just about nothing about _when_ the next >>> photon will be detected, they will appear to arrive randomly >>> (like radioactive radiation - Poisson distribution). >> >>yes. >> >>> So the "wave packet" of these photons must have a very >>> narrow frequency spectrum and must be very long in space. >> >>No. The packets are spread out in space, but each is very short. >> >>> Does it make sense to say that these photons are >>> light seconds long? :-) >> >>No. Only that they are light seconds apart. >> >>> Don't think so. >>> That the wave packet is long only means that we don't >>> know when the photon will be detected. >> >>We know when it is detected. If it is millions of cycles long, does >>detection take place at the beginning or the end of the millions of >>cycles? >> >>If it is millions of cycles long, what happens if a shutter is dropped >>into the focal plane in the middle of the wave train? >> >>> But yet it is detected at an instant - not gradually. >> >>That would indicate that it can NOT be millions of cycles 'long'. >> >>I see no reason for it to be more than 1 cycle 'long'. > > Ah! but what is a 'cycle'? > .....a cycle of what? A cycle of E <---> M energy transfer. Where the E and M fields exchange energy. A rotation of the energy magnitude vector in EM space. A cycle of the AC voltage in my transmitting antenna. A cycle of the AC voltage induced by the passing M field in my receiving antenna. A cycle of the current in my loop transmitting antenna [which produces an M field in space] A cycle of the current induced in my loop receiving antenna by the M field of the passing radio wave. .... -- 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 2 Aug 2005 07:10 bz wrote: > H@..(Henri Wilson) wrote in > news:mc8te1p1jcju71a65e4t4q6nmn3abr170d(a)4ax.com: > > > On Mon, 1 Aug 2005 21:42:57 +0000 (UTC), bz <bz+sp(a)ch100-5.chem.lsu.edu> > > wrote: > > > >>"Paul B. Andersen" <paul.b.andersen(a)deletethishia.no> wrote in > >>news:dcm17g$9u5$1(a)dolly.uninett.no: > >> > >>> bz wrote: > >>>> "Jeff Root" <jeff5(a)freemars.org> wrote in > >>>> news:1122862205.456748.163740 @g44g2000cwa.googlegroups.com: > >>>> > >>>> > >>>>>George replied to Bob: > >>>>> > >>>>> > >>>>>>>The spectra seem to indicate that the single photons > >>>>>>>have very narrow bandwidth [as I would expect]. > >>>>>> > >>>>>>If a photon has a specific energy and that is > >>>>>>proportional to frequency, then a single photon > >>>>>>has a unique frequency hence zero bandwidth and > >>>>>>infinite duration >:-( > >>>>>> > >>>>>>At least it does with a semi-classical view. > >>>>>> > >>>>>>If you include Heisenberg, then the uncertainty > >>>>>>in the measured energy relates to the uncertainty > >>>>>>in the frequency which depends on the time over > >>>>>>which the frequency is measured, hence the > >>>>>>bandwidth is related to the method of measurement, > >>>>>>and I don't need to point out the crucial role of > >>>>>>measurement methods in QM. > >>>>>> > >>>>>>As a result, I don't think a photon has a specific > >>>>>>length or duration, but the idea of it as a single > >>>>>>cycle with hard ends at the zero crossings can be > >>>>>>ruled out as too simplistic. > >>>>> > >>>>>The notion that a single photon can have a bandwidth seems > >>>>>absurd to me. For reasons analogous to the notion that the > >>>>>North Pole can have a longitude. It seems obvious that the > >>>>>property of bandwidth only applies to statistical collections > >>>>>of photons, or waves. > >>>>> > >>>>>I'm not sure it makes sense to talk about the frequency of a > >>>>>single photon, either. Any photon has a particular, measurable > >>>>>energy which is associated with a particular frequency, but > >>>>>there is no way to measure that frequency. Only by analyzing > >>>>>the behavior of a collection of photons does the property of > >>>>>frequency become evident. The analysis shows that f = E/h, > >>>>>so you can *know* the frequency of a single photon within the > >>>>>limits of uncertainty, but you can't actually measure it. > >>>>> > >>>>>If you have enough photons to directly measure their frequency, > >>>>>then you have enough photons to detect their bandwidth. > >>>>> > >>>> > >>>> > >>>> The question is 'how big'[long] is a photon. > >>>> > >>>> I can't see any reason that it should be more than one cycle in > >>>> length. > >>> > >>> It doesn't make much sense to talk about the "length" of a photon. > >>> A photon is a point particle. > >> > >>Something can be a point when seen from one direction and still have > >>duration (length) along another axis. > >> > >>>> There is a paper > >>>> http://jchemed.chem.wisc.edu/JCEWWW/Articles/DynaPub/DynaPub.html#ref1 > >>>> 6 That I disagree with. They appear to believe that each photon > >>>> consist of a wavetrain that is millions of cycles long. > >>> > >>> Remember that a "photon" is the particle aspect of the wave-particle > >>> duality. > >> > >>A photon is the name we have given to the smallest possible 'bundle' of > >>EM energy. In some experiments it looks like a wave, in some, it looks > >>like a particle. Limitiations of our testing equipment. > >> > >>Some equations treat it like a wave, some like a probability function, > >>some like a particle. > >> > >>None [that I know of] encompass all the photons observed properties. > >> > >>> It is true that you can make a classical (according to Maxwell) > >>> "EM wave packet" which is limited in time and space, and which has > >>> the energy of one photon. According to Fourier this "wave packet" > >>> must have a certain relationship between the width of the spectrum > >>> (spread of frequencies) and the extension in space. > >>> The narrower the spectrum, the longer in space, and vice versa. > >> > >>I understand FT and FFT, modulation and what information theory says > >>'must' happen. > >> > >>> But you cannot equate this wave packet to a photon - a particle. > >>> You must consider it to be a probability function. > >>> The width of the spectrum is then the uncertainty in the frequency > >>> and thus the energy of the photon, and the extension in space > >>> is the uncertainty in time (since the wave packet is propagating > >>> the spatial extension can be interpreted as an uncertainty in time). > >> > >>I agree. I think there is an uncertainly in time for single photons. A > >>small fraction of the time of one wavelength, a small phase uncertainty, > >>should suffice. > >> > >>> The relationship mentioned above is thus in accordance > >>> with the uncertainty principle. > >>> > >>>> Their theory seems to be falsified by femtosecond laser pulses. > >>>> There are some that would be less than 2 cycles at the frequency of > >>>> the laser. Also, the max keying speed of ELF transmission would seem > >>>> to preclude any requirement for millions of cycled per photon. > >>> > >>> Quite. > >>> If the pulses are very short and determined with high precision > >>> in time (very short wave packet), the uncertainty in energy > >>> must be high (Wave packet with very wide frequency spectrum.) > >> > >>Or there must be some uncertainly in the exact time the photon was > >>emitted by the transmitting antenna. > >> > >>> But I will repeat: > >>> It doesn't make sense to talk about the length of a photon. > >> > >>It would make an interesting experiment, if I had the equipment to do > >>switching at zero crossing and sent 1 cycle at 160 meters [the 1.8 MHz > >>amateur band], I think I should create a bunch of 160 meter photons. > >>They would probably be spread out a bit in time. > >> > >>> Consider this: > >>> We observe the H-alpha line from a very weak astronomical > >>> source. With modern CCDs, we can literally count the photons > >>> as they arrive, maybe only a very few photons per second. > >> > >>yes. > >> > >>> If we use a spectrometer, we can see that the spread in > >>> frequency/energy is very small (it's a spectral line). > >> > >>yes. > >> > >>> But you can say just about nothing about _when_ the next > >>> photon will be detected, they will appear to arrive randomly > >>> (like radioactive radiation - Poisson distribution). > >> > >>yes. > >> > >>> So the "wave packet" of these photons must have a very > >>> narrow frequency spectrum and must be very long in space. > >> > >>No. The packets are spread out in space, but each is very short. > >> > >>> Does it make sense to say that these photons are > >>> light seconds long? :-) > >> > >>No. Only that they are light seconds apart. > >> > >>> Don't think so. > >>> That the wave packet is long only means that we don't > >>> know when the photon will be detected. > >> > >>We know when it is detected. If it is millions of cycles long, does > >>detection take place at the beginning or the end of the millions of > >>cycles? > >> > >>If it is millions of cycles long, what happens if a shutter is dropped > >>into the focal plane in the middle of the wave train? > >> > >>> But yet it is detected at an instant - not gradually. > >> > >>That would indicate that it can NOT be millions of cycles 'long'. > >> > >>I see no reason for it to be more than 1 cycle 'long'. > > > > Ah! but what is a 'cycle'? > > .....a cycle of what? > > A cycle of E <---> M energy transfer. Where the E and M fields exchange > energy. > > A rotation of the energy magnitude vector in EM space. > > A cycle of the AC voltage in my transmitting antenna. > A cycle of the AC voltage induced by the passing M field in my receiving > antenna. > > A cycle of the current in my loop transmitting antenna [which produces an M > field in space] > A cycle of the current induced in my loop receiving antenna by the M field > of the passing radio wave. Nature can do this without taking a maths class: http://mathworld.wolfram.com/FourierTransform.html Sue... > ... > > > > > > > -- > 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 2 Aug 2005 08:20 jgreen(a)seol.net.au wrote in news:1122960081.759862.165870 @g14g2000cwa.googlegroups.com: > Jim Greenfield > c'=c+v > Jim, what about the c'=c-v photons from sources going away from us? Do you believe in the 'extinction' explanation for lack of evidence for c'=c+/-v photons? If so, how do the c'=c-v photons gain velocity so as to get up to c? -- 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: Paul B. Andersen on 2 Aug 2005 09:49
sue jahn skrev: > "Paul B. Andersen" <paul.b.andersen(a)deletethishia.no> wrote in message news:dclsna$41n$1(a)dolly.uninett.no... > > sue jahn wrote: > > > You are of course welcome to advance an opinion > > > about how an axel should behave if it were repeating > > > a geosynchronous clock to the ground or if it were > > > repeating a ground clock to a geosynchronous satellite. > > > Neither you nor Bz seem able to interpret what Einstein's > > > relativity say's the shaft should do. > > > > Why do you think I should have any problem with this? > > This is yet another old non paradox. > > > > Let there be a clock A on the ground at equator. > > Let there be a clock B in geostationary orbit. > > Let both clocks be on the same radius. > > > > Let A measure the proper duration of one Earth rotation to be T. > > Then, as you now know and have accepted is experimentally > > verified for clocks in GPS orbit, B will measure the proper > > duration of one Earth rotation to be longer, T + delta_T. > > > > Let there be an axle between the two clocks. > > Let this axle rotate in such a way that there is no > > mechanical stress in the axle. > > Let the axle rotate N times during one Earth rotation. > > > > A will measure the rotational frequency to be f_g = N/T > > while B will measure it to be f_s = N/(T + delta_T). > > > > So the ground clock will measure the axle to rotate > > faster than the satellite clock will, but both will > > agree that the axle rotates N times per Earth rotation. > > > > frequency * duration = number_of_rotations > > f_g*T = N > > f_s*(T + delta_T) = N > > > > Loosly said: > > "The satellite clock will see the axle rotate slower, > > but for a longer time." > > > > Paul > > <<geosynchronous satellite.>> > Neither will see the earth rotate. > So your experssion: > > <<N times per Earth rotation.>> > > Reduces to division by zero. Wasn't this response a bit too stupid even for you? :-) Paul, amused |