X-Message-Number: 20994 From: "michaelprice" <> References: <> Subject: colours Date: Wed, 29 Jan 2003 00:08:30 -0000 Robert Ettinger hopes: > Maybe I'll outlive him. An ungenerous thought, but at least amenable to verification - eventually :-) > Anyway, Michael Price writes: > >> It is not our observations or degree of knowledge of the >> posited internal structure of electrons that tells two >> electrons to interfere but the fact that the two electrons >> are identical [that permits the interference.] > >> Open any text book on quantum theory and you will find >> realms of calculations regarding the different behaviour of >> identical and non-identical particles. > > This is just a way of saying that you DEFINE "identity" by > interference characteristics, as you have so far observed > them. Interference between particles is observed if and only if the particles are identical, yes. But a particle can also interfere with itself, so the two terms are not synonymous. > Sufficiency is not necessity, and interference is not the > only phenomenon. You have some other phenomenon in mind? > Can waves of different frequency interfere with each other? > Yes, although this is harder to observe than with waves of > the same frequency. If a "red" photon and an "orange" > photon interfere with each other, are they identical? A clever argument, but flawed. Two photons (= particles of light) of different frequency (= colour) will not interfere with each other, except to the extent that the photon detector (which detects the interference) disturbs the photons' frequencies. Your typical photon detector (e.g. photographic plate or film or photomultiplier tube or radio antennae) will disturb the photons' frequencies as it localises them, as a consequence of the Heisenberg uncertainty principle. In other words the attribute of "colour" is not stable as the photons are processed. (I am assuming that the photons in questions start off with definite frequencies and not with overlapping bandwidths. i.e. that the terms "red" and "orange" correspond to precise starting frequencies.) Cheers, Michael C Price ---------------------------------------- http://mcp.longevity-report.com http://www.hedweb.com/manworld.htm Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=20994