How can the MMx math be corrected?
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From: Tom Roberts on 4 May 2010 11:57 harald wrote: > On May 2, 7:00 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: >> In SR you can select ANY inertial frame. There is no need to select one frame >> and use it throughout the year. > > when you change inertial frame, you also declare > your earlier measurement as having been done in a "moving" frame. So what??? Who cares??? From the standpoint of SR this is irrelevant. The point at issue is: do the fringes move as the interferometer is rotated? NOTHING else matters. The simplest and easiest way to apply SR to the physical situation is to use the inertial frame of the interferometer's center [#], and using that frame it's clear that SR predicts the fringes do not move as the interferometer is rotated. NOTHING else matters -- it does not matter if you think that is a "moving frame" or not, because "frames" are not part of the experimental observation -- ALL that matters is the motion of the fringes as the interferometer is rotated. [#] From the structure of SR, we KNOW that the same conclusion will result from an analysis in any other inertial frame, in which the interferometer is moving. But using any such frame for the analysis is MUCH more complicated.... > It's reassuring that you understand that the variation of velocity of > the Earth is relevant for stellar aberration. But that makes it even > more amazing that you cannot (or refuse to) understand that the > variation in velocity is equally relevant for Lorentz contraction in > SRT (which the OP called "SRT math"). You, too, are confused about what "Lorentz contraction" means in SR -- the arms themselves are COMPLETELY UNAFFECTED by "Lorentz contraction". What matters is whether the prediction of the theory corresponds to the experimental observation. Michelson and Morley made observations at different times of the year. SR predicts no fringe motion at any time of the year, which is consistent with what they observed. YOU may think the motion around the sun is "relevant", and in other theories it certainly is relevant, but in SR it is not. All that matters for the SR analysis I outlined earlier is: a) the arms' proper lengths remain constant, and b) non-inertial motions are small enough so the interferometer can be considered to be at rest in some inertial frame during a single measurement (observation of fringe position at a single orientation). Earlier I considered a "measurement" to be one full rotation of the apparatus. It is cleaner and simpler to consider each observation of fringe position separately. Because of the structure of SR, it does not matter that different measurements are analyzed in different inertial frames (whether separated by a few seconds or a fraction of a year). > the OP (DDRR) obviously meant that it is "physically > impossible" to get a null result with a *moving* interferometer > without a modified length of at least one of the arms, assuming that > the speed of light is completely unaffected by the speed of the Earth. Again, this is just plain not true -- that statement is implicitly adding unstated conditions that erroneously limit what can be considered, and they exclude SR inappropriately. SR is a counterexample: in SR the length of the arms does not change (even for a *moving* interferometer), the speed of light is unaffected by the speed of the earth, and yet SR predicts a null result. Note carefully the meanings of the words used: "length of the arms" relates to THE ARMS THEMSELVES, and does NOT refer to the distance some observer moving relative to the arms might happen to measure between their endpoints. At base, this discussion hinges on the meanings of the words used; you, Paul, and DDRR all use unacknowledged PUNS on the meaning of "length" -- the word has different meanings at different places in your statements. DON'T DO THAT! If you guys were careful about the meanings of the words you use, you would not be confused, and would not need this discussion. At base this is due to the implicit and unquestioned assumptions that you carry, many of which are wrong. You MUST learn to discard this baggage, or you will never be able to understand modern physics. Just like Paul you need to learn how to read, write, and think more accurately. Ditto for DDRR. Unacknowledged PUNs like that will destroy any argument you attempt to make. In particular: when an embankment observer marks the endpoints of a moving train simultaneously on the embankment (with pre- positioned assistants), and then measures the distance between marks, he cannot call that distance the "length of the train" because it does not relate to JUST the train. He could call it "the length I measured for the train", or "the length of the train in the embankment frame". If you guys were similarly careful in phrasing your statements, your confusions would evaporate. (Well, you also need to pick one theoretical context and stick to it.) Tom Roberts
From: harald on 4 May 2010 12:46 On May 4, 5:57 pm, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > harald wrote: > > On May 2, 7:00 am, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > >> In SR you can select ANY inertial frame. There is no need to select one frame > >> and use it throughout the year. > > > when you change inertial frame, you also declare > > your earlier measurement as having been done in a "moving" frame. > > So what??? Who cares??? From the standpoint of SR this is irrelevant. It would be irrelevant for SR if SR wasn't meant to also apply to moving objects; and it would be irrelevant for this thread if the topic concerned objects that are all the time in the same state of motion. > The point at issue is: do the fringes move as the interferometer is rotated? No, that is definitely NOT the topic of this thread... > NOTHING else matters. That says it all: you are incapable of considering the topic that the OP discusses. Worse, you insist on making inconsistent statements. [..] > > It's reassuring that you understand that the variation of velocity of > > the Earth is relevant for stellar aberration. But that makes it even > > more amazing that you cannot (or refuse to) understand that the > > variation in velocity is equally relevant for Lorentz > > contraction in SRT (which the OP called "SRT math"). > > You, too, are confused about what "Lorentz contraction" means in SR -- the arms > themselves are COMPLETELY UNAFFECTED by "Lorentz contraction". > [...] > > the OP (DDRR) obviously meant that it is "physically > > impossible" to get a null result with a *moving* interferometer > > without a modified length of at least one of the arms, assuming that > > the speed of light is completely unaffected by the speed of the Earth. > > Again, this is just plain not true -- that statement is implicitly adding > unstated conditions that erroneously limit what can be considered, and they > exclude SR inappropriately. SR is a counterexample: in SR the length of the arms > does not change (even for a *moving* interferometer), the speed of light is > unaffected by the speed of the earth, and yet SR predicts a null result. > Note carefully the meanings of the words used: "length of the > arms" relates to THE ARMS THEMSELVES, and does NOT refer to the > distance some observer moving relative to the arms might happen > to measure between their endpoints. The meanings of your words are inconsistent: either one discusses an observation from a system in which the interferometer is moving, or one discusses it from a system in which it is in rest. You flip-flop from one system to another in a single description. SR predicts a null result for a moving interferometer (which is by *definition* of the word "moving" *not* measured relative to a co- moving or "proper" coordinate system), and you know very well that the length in the direction of motion is shortened in the same system which was used to define it as "moving". > At base, this discussion hinges on the meanings of the words used; you, Paul, > and DDRR all use unacknowledged PUNS on the meaning of "length" -- the word has > different meanings at different places in your statements. No, it is you - as shown here above. Length (in contrast to "proper length") means in this context always the length as *measured* in the same reference system as to which the word "moving" refers. It is better to be specific, but an intelligent reader should be able to understand a consistent use of references! If you answer to a newcomer such as DDRR it requires a minimal effort to follow what he is thinking, without imposing *your* way of formulating things on him and then giving replies that are completely besides the point. > DON'T DO THAT! If you > guys were careful about the meanings of the words you use, you > would not be confused, and would not need this discussion. I'm not confused, while you risk to confuse people with your stubborn flip-flopping between references without any concern for the topic that they discuss. > At base this is due to the > implicit and unquestioned assumptions that you carry, many of which are wrong. > You MUST learn to discard this baggage, or you will never be able > to understand modern physics. > Just like Paul you need to learn how to read, write, and > think more accurately. Here you gave me good laugh Tom. :-) Did you publish any paper on SRT and length contraction in a quality peer reviewed journal? [..] (Well, you also need to pick one theoretical context > and stick to it.) Tom, the theoretical context of this thread is to consider a *moving* Michelson interferometer, and the therewith consistent length of the *moving* arms (which implies that the lengths are *not* described in rest!). If your brain had not lost its flexibility, you could have had a constructive discussion with the OP by now. Ciao, Harald
From: whoever on 4 May 2010 18:51 "harald" <hvan(a)swissonline.ch> wrote in message news:e74170c7-7abf-4d1f-b2d9-c7c15ff109b1(a)e2g2000yqn.googlegroups.com... [snip] > No, that is definitely NOT the topic of this thread... What IS the topic? Why does anyone think that the MMX math needs to be corrected? In what was is it incorrect? --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Paul Stowe on 4 May 2010 20:45 On May 4, 12:28 am, harald <h...(a)swissonline.ch> wrote: > On May 3, 5:19 pm, PaulStowe<theaether...(a)gmail.com> wrote: > > > Not one of its arms Harald, both of its arms, since the apparatus is > > rotated. > > Right - at least we both seem to understand now what the OP was > talking about. ;-) > > > Further, it makes no difference that Earth's speed varies > > with the seasons, the magnitude of the physical field distortion > > (Contraction in the direction of motion) is solely a result of the > > instantaneous velocity affecting the field at any given moment. > > Sure - but here you miss two subtle points which I tried to make > clear, but here once more: > > 1. M-M tested at different seasons to guarantee that at least at one > time the "absolute speed" would be significantly different from > zero. > 2. when discussing SRT, we may choose a frame in which the Earth is > momentarily in rest; the fact that MMX is performed with the same > result in different seasons is therefore pertinent for the topic of > this thread. I don't think I missed anything. The main point (and central to SRT working properly) is that fields constantly adjust themselves to the velocity they are experiencing. However, any change in velocity results in a non-inertial situation. Thus as Tom well knows, the Earth's surface isn't a inertial frame, it very close to one however. > > When > > the fields constituting the material arms of an interferometer are > > rotated they maintain their physical orientation wrt to the motion, > > thus the overall length changes as the angle to the motion does. That > > is, specifically, what I was referring to with the equation Sqrt(1 - > > [v'/c]^2) and v' = v Cos t. Let angle t be zero in the direction of > > motion and you'll see that v' disappears at 90 & 270 degrees and > > becomes -v at 180. This is a necessary physical aspect of the system > > which maintains continuity of the field wrt to all of its elements, > > given the actual invariance and source independence of c. > > > Yes, it is physically impossible to get a null result without this > > effect and I don't think Tom disputes this. So, what, exactly, is > > your point? > > My point was what I stated that it was: Tom misunderstood what DDRR > was talking about and you next jumped in with more confusion, as I > explained; that is not helpful for him. But as he is clearly gone now, > we're talking to nobody. End of effort! He doesn't 'misunderstand', he denies it occurs when a FOR is 'locally' at rest. > Cheers, > Harald
From: Tom Roberts on 4 May 2010 22:03
Paul Stowe wrote: > I don't think I missed anything. You, you mist LOTS of things. For instance, this: > The main point (and central to SRT > working properly) is that fields constantly adjust themselves to the > velocity they are experiencing. Nonsense. I assume you mean the electromagnetic fields. In SR and the related theory of classical electrodynamics, the electromagnetic field is a 2-form that is INVARIANT [#]. In particular, the field cannot "experience velocity", because it is a function on the manifold (which is the relevant definition of "field"). And because it _IS_ a field, it cannot "adjust itself", either -- it is INVARIANT (under coordinate transforms). [#] In QED, the field is also invariant, but it is a quantum field which goes well beyond the scope of this discussion. You REALLY need to learn what SR _ACTUALLY_ says. But be sure to read ACCURATELY, and discard all your incorrect baggage before attempting to study it -- that baggage has quite clearly invalidated what you think you know about SR. Tom Roberts |