Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Phil Hobbs Newsgroups: sci.electronics.design Subject: Re: Quantum mystics Date: Mon, 10 Jun 2024 18:26:49 -0000 (UTC) Organization: A noiseless patient Spider Lines: 65 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Mon, 10 Jun 2024 20:26:49 +0200 (CEST) Injection-Info: dont-email.me; posting-host="3f07d48eb33b83eb162af14468bab0e3"; logging-data="619302"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/ohrdbh80MGeGY1oUiYEBK" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:wfzD6QAEM++1YpaL5tVgeZ6BL60= sha1:4kMiQ5scryNQRq+qAf6CcmhwMg8= Bytes: 4106 Martin Brown <'''newspam'''@nonad.co.uk> wrote: > On 10/06/2024 17:25, Jeroen Belleman wrote: >> On 6/10/24 16:20, john larkin wrote: > >>> But photon entanglement can't be explained, or even thought about, in >>> classic-physics terms. >>> >>> Nor can single-photon interferance. >>> >>> Just accept and enjoy it. >> >> That's false! Entanglement and interference can easily be understood >> in terms of waves and quantized detectors. It's the QM view, with its >> imagined photon particle flying everywhere at once that is confusing. > > But that world view is backed up by experiments. > > Particles can behave as waves and waves can behave as particles > depending on the experiment. The particle isn't "everywhere at once" > either it is trapped in a spherical shell radius vt expanding around its > point of origin with the amplitude of the wavefunction representing the > chances of finding it at any particular position. > >> What size do you imagine a photon to be? > > Depends on the wavelength of the photon but to have a well defined > frequency the amplitude envelope has to be a good few wavelengths long > and to agree with causality the leading edge must be zero until > sufficient time has passed from its emission to reaching its target. I > expect that there is a canonical shape for a photon amplitude envelope > for given df/f but I don't know what it is or if it has ever been computed. > > This aspect of size of a photon always seemed very awkward to me when > working at 21cm neutral hydrogen and measuring what are essentially tiny > correlations in narrowband random noise from extremely remote mostly > point sources over a large number of different antenna pairs. What is > pretty clear is that the correlations of such signals are good enough > even on planetary dimensions for VLBI to work! Sticking with the semiclassical picture of photodetection is good, because it avoids almost all of the blunders made by the photons-as-billiard-balls folk, but it doesn’t get you out of the mystery. The really mysterious thing about photodetection is that a given photon (*) incident on a large lossless detector gives rise to exactly one detection event, with probability spatialy and temporally weighted by E**2. Doesn’t seem so bad yet, but consider this: If the detector is large compared with the pulse width/c, distant points on the detector are separated by a spacelike interval. That means that so when point A detects it, there is no way for the information reach point B before the end of the pulse, when E drops to zero, and yet experimentally point B doesn’t detect it. (*) a quantized excitation of a harmonic oscillator mode of the EM field in a given set of boundary conditions) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics