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Photons at same place at the same time

by bassplayer142
Tags: photons, time
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bassplayer142
#1
Dec17-07, 03:21 PM
P: 422
I have a friend who told me about a tv show he just watched that claimed to do just this. I can't find any information and we don't have a name so I don't have much to go by. If anyone know of recent advances or if this is nothing new I wouldn't mind a few links or something. I guess they also said something about the proof of parallel universes because of it. thanks.
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Flyin G
#2
Dec17-07, 06:42 PM
P: 2
has anyone put forth this notion of relativity applying to photons in the slit test......saying that photons are existing relative to space and time seperately (and simultaneously) and that we as observers can only observe the photon relative to spacetime. could the interference pattern of photons travelling through the two slits be explained by saying the photon we send, we observe existing in spacetime (one photon)....the photon relative to time would travel through one slot, the photon relative to space can only travel through the other one (or perhaps with the notion that both time and space are infinite, the photon exists everywhere relative to space, and also exists infinitely relative to time, allowing each slot to be travelled through)...once on the other side we observe the spacetime photon which has interfered with itself , one relative to time, one relative to space. space and time interfering to be observed as a wave in spacetime.
Flyin G
#3
Dec17-07, 07:10 PM
P: 2
Bassplayer....youtube.com , search quantum physics, there are a few cartoons that illustrate these ideas simply.........then try the books "einstein for beginners", "the elegant universe", and "warped passages" they may offer some insight before attending a university.

reilly
#4
Dec18-07, 11:15 AM
Sci Advisor
P: 1,082
Photons at same place at the same time

Quote Quote by bassplayer142 View Post
I have a friend who told me about a tv show he just watched that claimed to do just this. I can't find any information and we don't have a name so I don't have much to go by. If anyone know of recent advances or if this is nothing new I wouldn't mind a few links or something. I guess they also said something about the proof of parallel universes because of it. thanks.
Yes, many photons can be at the same place at the same time -- this follows from the invariance of Bose states under interchange of particles. Look up Bose Condensation and Superfluidity, both of which involve lots of zero-momentum bosons -- same place can apply equally well to configuration and momentum spaces.
Regards,
Reilly Atkinson
jnorman
#5
Dec18-07, 11:58 AM
P: 308
you cannot really say anything about a photon, including its location, in between the time it is emitted and the time it is absorbed.
reilly
#6
Dec19-07, 09:42 AM
Sci Advisor
P: 1,082
Quote Quote by jnorman View Post
you cannot really say anything about a photon, including its location, in between the time it is emitted and the time it is absorbed.
If what you say is true, then the entire apparatus of the path-integral approach would be incorrect.
Regards,
Reilly Atkinson
jnorman
#7
Dec19-07, 05:03 PM
P: 308
hi reilly - i stand by my comment. do you wish to further illuminate your position on this?
reilly
#8
Dec21-07, 03:41 PM
Sci Advisor
P: 1,082
Basic QM says a wave function defines a probability density in its defining space. This holds for photons as well as for massive particles. A probability density in configuration space, suitably integrated, gives the probability to find a photon anyplace you want. Indeed, there are some tricky points -- photons cannot be localized, but they can be almost localized. This and other subtle points can be found, extensively discussed, in Optical Coherence and Quantum Optics, Mandel and Wolf. That is, we know the in-between for a photon in terms of probability.

Regards,
Reilly Atkinson
jnorman
#9
Dec22-07, 03:37 PM
P: 308
hi reilly - i guess i would dispute the comment that they can almost be localized. my understanding is that photons travel by all possible paths, and it certainly seems intuitive considering that since they "travel" at C, where distance and time have no meaning, that once emitted, a photon occupies all of space time until it is again absorbed. feynman's path integral based on probablility is a reasonable way of predicting where a photon might end up, but really says nothing about which path it actually took to get there. i used to argue your side of this myself, but have been beaten down by others who i consider more knowlegdeable than me.


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