Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Sylvia Else Newsgroups: sci.physics.relativity Subject: Re: Question For Relativity 'Experts'. Date: Wed, 19 Oct 2016 17:57:58 +1100 Lines: 32 Message-ID: References: <239a6125-63d1-4ae8-8762-4db0850f55c6@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: individual.net h56WWVRrbM54+EwPzl9BBAYiIICeQQR0o/StT3/q/c0IRYZGCd Cancel-Lock: sha1:ciL8L3wTCLwSkASG3ncVwtn99D4= User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 In-Reply-To: <239a6125-63d1-4ae8-8762-4db0850f55c6@googlegroups.com> Xref: csiph.com sci.physics.relativity:396096 On 9/10/2016 12:28 AM, alsor@interia.pl wrote: > W dniu piątek, 7 października 2016 05:46:08 UTC+2 użytkownik Sylvia Else > >> I take it, then, that you haven't done such an experiment. You're just >> assuming the result. >> >> Sylvia. > > An experiment which measures the one-way speed is very simple: > just use a radar. > > But you must first to calibrate your instrument correctly, > so you should measure two times, two different speeds... at least. > The difficulty with measuring the one way speed is that to do it one needs to make time measurements at the start and end, and subtract one from the other to determine the transit time. But subtracting one from the other only makes sense if the clocks are synchronised. There are essentially two ways of synchronising clocks - keeping them apart and sending signals between them, or bringing them together and then moving them apart. In the first case, it begs the question of how fast the signals propagate, and whether they propagate at the same speed in both directions. In the second case, the question is whether the clocks will remain synchronised when they are moved apart. Sylvia.