Path: ...!2.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: sci.physics.relativity Subject: Re: Sync two clocks Date: Fri, 23 Aug 2024 11:51:42 +0300 Organization: - Lines: 64 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 23 Aug 2024 10:51:42 +0200 (CEST) Injection-Info: dont-email.me; posting-host="26b8411c2e56db26e0b6475430bba58d"; logging-data="913260"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/mn+GHgQ2poQPoiMaMx5WA" User-Agent: Unison/2.2 Cancel-Lock: sha1:ctFON1Lgl/cEw4ue9RUG9yS85VI= Bytes: 3703 On 2024-08-22 07:02:47 +0000, Thomas Heger said: > Am Mittwoch000021, 21.08.2024 um 20:42 schrieb Paul.B.Andersen: >> Den 20.08.2024 17:12, skrev Richard Hachel: >>> Le 20/08/2024 à 15:39, Python a écrit : >>> >>>> Hachel now pretends that tB − tA = t'A − tB can be true or false >>>> depending on the observer. >>> >>> You are lying. >>> >>> I do not claim it "now". This is what I have always said for at least 40 years. >>> >>> Now, yes, obviously I assume it. >>> >>> The value (tA'-tA) = 2AB/c is the same not only for A and B, but also >>> for all the stationary points of the inertial frame of reference of A >>> and B. >>> >>> Better, if I change frame of reference it will remain true, by >>> invariance of the transverse speed of light in any frame of reference. >>> >>> On the other hand the value tB-tA (go) will vary for most observers in >>> R (where A and B are stationary), as will the value tA'-tB (return). >>> >>> But you cannot understand this, because 1. You are stupid and because >>> 2. because you are tied up with relativistic thoughts all learned, but >>> false. >>> >>> R.H. >> >> Richard, read your watch NOW. Write down the time nn:nn:nn. >> The time nn:nn:nn is a proper time (read off a clock), it is >> invariant, not depending on frame of reference. >> >> Nobody can have another opinion of what time YOU read of YOUR watch. >> >> How is it possible to fail to understand this? >> >> If we have two stationary clocks in an inertial frame, >>  and clock A shows tA = t1 when it emits light, >>  and clock B shows tB = t1 + td when the light hits it, >>  and clock A shows tA'= t1 + 2⋅td when it is hit by the reflected light, >> >> then tA, tB, tA', t1 and td are all proper times which are frame >> independent (invariants) and "the same for all". >> >>  tB − tA = t'A − tB = td >> >> The transit time td is a frame independent invariant and >> the same in both directions, which means that the clocks according >> to Einstein's _definition_ are synchronous in the inertial frame. > > You introduced t_d or 'transit time' (aka 'delay'), while Einstein > didn't use any of these terms. Einstein used tB - tA and similar expressions. Nothing else needs be said about delays. The equation tB − tA = t'A − tB and the text that describes the situation and defines what tA, t'A and tB mean define clearly and unambiguously what simultaneity and synchronity mean. -- Mikko