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Path: ...!weretis.net!feeder8.news.weretis.net!pasdenom.info!from-devjntp Message-ID: <dMbLnMKAldhrBIqwK02iVir2F64@jntp> JNTP-Route: news2.nemoweb.net JNTP-DataType: Article Subject: Re: "Time" vs "physical time" References: <17e914f508c7a9cf$96455$546728$c2565adb@news.newsdemon.com> <dwvnP-SoKZPwHpz6HgPhxwtG7e4@jntp> <v92ugo$4cam$1@dont-email.me> <XhF-ilyxW2WRkQK5uYxoOVgm1rU@jntp> <v98g6k$srl7$1@dont-email.me> <DXGSZoOy8NKrDPHyCw-4Caf7a64@jntp> <v9asjr$2qc1e$1@dont-email.me> Newsgroups: sci.physics.relativity JNTP-HashClient: yVwBpQtNmdwN5Q8sFmaKVa1YQG4 JNTP-ThreadID: 17e914f508c7a9cf$96455$546728$c2565adb@news.newsdemon.com JNTP-Uri: http://news2.nemoweb.net/?DataID=dMbLnMKAldhrBIqwK02iVir2F64@jntp User-Agent: Nemo/0.999a JNTP-OriginServer: news2.nemoweb.net Date: Sun, 11 Aug 24 19:05:59 +0000 Organization: Nemoweb JNTP-Browser: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36 Injection-Info: news2.nemoweb.net; posting-host="e8cbf2474b472b9bb79db3dccb6a856bc1d05409"; logging-data="2024-08-11T19:05:59Z/8983192"; posting-account="4@news2.nemoweb.net"; mail-complaints-to="julien.arlandis@gmail.com" JNTP-ProtocolVersion: 0.21.1 JNTP-Server: PhpNemoServer/0.94.5 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-JNTP-JsonNewsGateway: 0.96 From: Richard Hachel <r.hachel@jesauspu.fr> Bytes: 4867 Lines: 91 Le 11/08/2024 à 19:32, "Paul.B.Andersen" a écrit : > Den 10.08.2024 23:35, skrev Richard Hachel: >> Le 10/08/2024 à 21:48, "Paul.B.Andersen" a écrit : >>> Den 08.08.2024 19:55, skrev Richard Hachel: >>>> Can you reformulate your question using a vast underground tunnel between Paris >>>> and Oslo, in which we could launch particles at high speed from Paris to Oslo and >>>> vice versa? >>>> >>>> We assume that the length of the tunnel would be 1320 kms. > >>> OK, let's assume that the length of the tunnel is exactly 1320 km. >>> We are using two clocks showing UTC+2h. But they have to be >>> more precisely synchronised than the clocks on the airports >>> which can not be expected to be synchronous to much better than >>> within a second. >>> >>> So we will use two atomic clocks which are synchronised >>> by GPS to show UTC+2h to within 1 ns. >>> >>> The particle we will use is a photon. >>> >>> A photon is sent from Oslo at the time 12.00.000000000 ± 1ns >>> and is detected in Paris at the time 12.00.004403046 ± 1ns >>> The measured speed of the photon is 299792461 ± 68 m/s >>> >>> A photon is sent from Paris at the time 13.00.000000000 ± 1ns >>> and is detected in Oslo at the time 13.00.004403046 ± 1ns >>> The measured speed of the photon is 299792461 ± 68 m/s >>> >>> Any problem with this? > >> >> No. >> >> Absolutely not. >> >> All you said is correct. >> >> R.H. >> > > OK. So you have realised that it is possible to synchronise > a clock in Oslo and a clock in Paris to within 1 ns if > we use the GPS. > > But have you realised that the clocks on the wall in > Oslo Airport and Paris Airport are synchronous to within > few seconds (probably better)? > > Please answer the question below, and don't flee yet again. > > Clocks in Oslo and Paris are showing the time UTC+2h. > > I leave Oslo Airport (Gardemoen Airport) when the watch on the airport > shows 12.00.00 > I arrive at Paris Airport (Charles De Gaulle Airport) when the watch > on the airport shows 13.30.32. > > The difference is T = 1h 30m 32s > > Question #1: > ============ > Is it possible to calculate the duration of the journey (measured > in the ground frame) by comparing the reading of the clock in Oslo > at the departure and the reading of the clock in Paris at arrival? > > Yes or no, please. > > > The distance in the ground frame between the airports is L = 1358.03 km. > > Question #2: > ============ > Is the real speed of the plane in the ground frame v = L/T = 900 km/h, > or is it impossible to know the real speed of the plane because > of the universal anisochrony? > > Yes or no, please. The principles of relativity do not apply to your example because the time measurements you use are of the order of seconds, and the speeds you use are far too low (airliners) to have consistent measurements. Can you take more classical examples of RR where we go faster or measure smaller quantities of time?The principles of relativity do not apply to your example because the time measurements you use are of the order of seconds, and the speeds you use are far too low (airliners) to have consistent measurements. Can you take more classical examples of RR where we go faster or measure smaller quantities of time? R.H.