Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Martin Brown <'''newspam'''@nonad.co.uk> Newsgroups: sci.electronics.design Subject: Re: Quantum mystics Date: Mon, 10 Jun 2024 18:28:06 +0100 Organization: A noiseless patient Spider Lines: 41 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Mon, 10 Jun 2024 19:28:07 +0200 (CEST) Injection-Info: dont-email.me; posting-host="151e811e6e95cd7b2ea8a77b54b302ce"; logging-data="581107"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/nO/tXELin4XIe2xxUDb0C4yjd6pEslpMTYOhboawGnQ==" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:f0+d/VH/B822EVmBZ3U9YF469RQ= Content-Language: en-GB In-Reply-To: Bytes: 2908 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! -- Martin Brown