Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Sylvia Else Newsgroups: sci.physics.relativity Subject: Re: Michelson got his mirrors wrong Date: Mon, 24 Oct 2016 14:24:46 +1100 Lines: 69 Message-ID: References: <74d02e12-cae5-494d-a598-051c1afd5de1@googlegroups.com> <954ac900-f947-46a2-aede-e3af424b719a@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net lv6iyc5y/m8vYXKqQi1ZqQ10HLvrbjkc5vSH6VamM7qtqgmWah Cancel-Lock: sha1:8hnfmPQF//KTeecpGYPzqZbowTg= User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 In-Reply-To: <954ac900-f947-46a2-aede-e3af424b719a@googlegroups.com> Xref: csiph.com sci.physics.relativity:396589 On 24/10/2016 2:00 PM, Peter Riedt wrote: > On Monday, October 24, 2016 at 9:46:22 AM UTC+8, Sylvia Else wrote: >> On 24/10/2016 12:06 PM, Peter Riedt wrote: >>> On Monday, October 24, 2016 at 8:42:14 AM UTC+8, Sylvia Else >>> wrote: >>>> On 23/10/2016 10:31 AM, Peter Riedt wrote: >>>> >>>>> However, every mirror, not only the mirrors of his >>>>> interferometer apparatus, partakes in the two motions of the >>>>> earth; rotation and orbit around the sun. The laws of >>>>> reflection have been established under these circumstances >>>>> and are the same for every mirror on earth and regardless of >>>>> their alignment with East, West, North and South and every >>>>> compass point in between. >>>>> >>>> Whether this is exactly true was not something that had been >>>> tested. >>>> >>>> If one takes seriously the proposition that light is a wave >>>> propagating through the aether, then the behaviour of mirrors >>>> follows directly from wave theory, and from the point of view >>>> of an observer moving through the aether, mirrors would not >>>> exactly obey that laws of reflection. >>>> >>>> In the end, it doesn't matter how much double-think you engage >>>> in - if you do the math right, you'll end up with the Lorentz >>>> transformation, regardless of what you believe is the cause. >>>> >>>> Sylvia. >>> >>> But Einstein said contraction is not real for comoving observers. >>> Was he wrong? >>> >> >> I'm sure this point has been made before - but I'll make it again. >> "Real" is a difficult word. You need a precise definition if you >> want to use it in such a question. >> >> But it's irrelevant here. You get the same mathematical result >> regardless. >> >> Sylvia. > > Yes, the usual defence of SR is that the term 'real' is not what it > means in English. That's not the case, it's just that in everyday usage, people are not so fixated on having an exact single meaning. Is a mirage real? Well, the thing apparently seen does not exist, or at least not where it appears to be, so in that sense it's not. But the physical processes that cause a mirage are well understood, and in that sense a mirage is real. No one loses any sleep over the distinction. I will definitely measure the length of a moving object as being less than will a co-moving observer. So if by length contraction, one means the results of measurement, then length contraction is real. On the other hand, different observers moving at different speeds will get different results, and they can't all be the true contracted length of the object, and in that sense the length contraction is not real. So it's only when you refuse to qualify your meaning of real in situations where it needs qualifying do you run into problems. Getting into arguments about the meaning of words is a completely pointless and time-wasting exercise. Pretending that a word has one meaning when it actually has many, and using that in an argument, is intellectually dishonest. Sylvia.