tag:blogger.com,1999:blog-8148573551417578681.post3701207240975830228..comments2024-03-27T19:47:13.475-07:00Comments on Dark Buzz: Defending a physical FitzGerald contractionRogerhttp://www.blogger.com/profile/03474078324293158376noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-8148573551417578681.post-77118852386503314622014-10-24T06:41:57.539-07:002014-10-24T06:41:57.539-07:00I agree with you that Lorentzian relativity has so...I agree with you that Lorentzian relativity has some explanatory advantages, and is a legitimate view. I tried to <a href="http://en.wikipedia.org/w/index.php?title=Length_contraction&diff=576500043&oldid=576215637" rel="nofollow">add a sentence last year</a> saying that to the Wikipedia article on <a href="http://en.wikipedia.org/wiki/Length_contraction" rel="nofollow">length contraction</a>, but I was overruled by other editors.<br /><br />I am puzzled as to why you would say that GR gives a comprehensible geometrical understanding, but not SR. After all, SR is just GR with the flat metric. Any GR explanation applying to flat spacetime should also be an explanation under the geometrical view of SR.<br /><br />I will address your main point, maybe in a subsequent blog post.Rogerhttps://www.blogger.com/profile/03474078324293158376noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-35575711248542966272014-10-24T04:43:41.624-07:002014-10-24T04:43:41.624-07:00“The impression that the LT involves some physical... “The impression that the LT involves some physical transmutation of "spacetime" might seem consistent with the change of that nature contemplated in general relativity (GR). But in GR that change affects in like manner all that occupies the region of space in question. In SR it is necessary to distinguish what actually changes from what is merely "observed" to change.<br /><br /> Consider two explorers, who we will call Buzz and Mary. They had been travelling, in separate space ships, side by side, in the same direction. But Buzz has veered away to explore a distant asteroid. Mary concludes from her knowledge of the LT that time must now be running more slowly for Buzz and that he and his ship have become foreshortened in the direction that Buzz is travelling relative to her. Buzz observes no such changes either in himself or in his ship. To Buzz, it is in Mary and her ship that these changes have occurred. Buzz is also aware that events that he might previously have regarded as simultaneous are no longer so. <br /><br /> But what has actually changed? No relevant physical change has occurred in Mary or her spacecraft. She has not accelerated. She is in the same inertial frame as before. Nor (ignoring gravitational effects, in this case negligible) has any actual, as distinct from observed, change occurred in the space through which the travelers are moving. To suggest otherwise would be to suppose that space is able to contract in one way for one particle and in a different way for another moving relatively to the first, albeit that the two (or at least their correspondingly contracted fields) could be occupying the very same piece of space. Even Buzz will have realized, as he observed the constellations contracting as he accelerated, that the stars were not in fact closing ranks around him.<br /><br /> A change of inertial frame has occurred for Buzz and his spacecraft. It must be this change that is the source of the changes that the two explorers are observing. It is not difficult to understand that Buzz's change of velocity may have caused a change in him that has affected how he is perceived by Mary. But it must also be the case, since nothing else has changed, that it is this same change in Buzz that has caused him to consider the (in fact unchanged) Mary in a different light. <br /><br /> Buzz will not sense that he has changed. After all everything in his inertial frame will have changed in like manner. Unlike the carousel rider who sees the fairground whirling about her, but is under no illusion as to what is really happening, Buzz has suffered relativistic changes in his vital processes, and lost the means of discernment. For Buzz the LT will describe very well his altered perspective. But it would be as inappropriate to explain length contraction, time dilation and loss of simultaneity as resulting from a physical transformation of space or spacetime as it would be to describe the rotation of an object in 3-space as a rotation of space rather than a rotation in space. <br /><br /> While one might wish to elevate the discussion by reference to differential manifolds, the spacetime continuum, or the Minkowski metric, the curious effects described by the LT must be explained by a change that occurs in matter as it suffers a "boost" from one inertial frame to another. Indeed the Minkowski metric should itself be seen as a kind of illusion, and as a consequence rather than the cause of this change in matter.”<br /><br /><br /><br />Dan Shanahanhttps://www.blogger.com/profile/11240342697478880476noreply@blogger.comtag:blogger.com,1999:blog-8148573551417578681.post-86733690531001804362014-10-24T04:41:13.896-07:002014-10-24T04:41:13.896-07:00Hi Roger,
I enjoy your blog, and appreciate the ...Hi Roger,<br /> <br />I enjoy your blog, and appreciate the attention you have given my recent argument for a Lorentzian relativity. I do also see the sense of some of your criticisms of my potted history of special relativity (SR).<br /><br />But we disagree fundamentally on the important issue – the physical origin of the Lorentz transformation (LT) - and it would help my understanding of how you understand the conventional spacetime approach if I could follow some comments you make regarding the Minkowski metric. <br /><br />You say:<br /><br />"In the preferred (Minkowski) view, the LT is not really a transmutation of space and time. Minkowski spacetime has a geometry that is not affected by motion. The LT is just a way to get from one set of artificial coordinates to another."<br /><br />and later:<br /><br />"The physics is all built into the geometry, and the contraction seems funny only because we are not used to the non-Euclidean geometry."<br /><br /><br />I would understand, and could accept, both passages if you were describing the non-Euclidean metric of the gravitational equation where we have the intuitive picture of a curved spacetime. But I cannot see what changes could actually be occurring in flat spacetime in consequence of the rotation described by the LT. You say that ”Minkowski spacetime has a geometry that is not affected by motion” and it is here in particular that I am not sure of your meaning. <br /><br /> I would say myself that whatever space might be, neither it nor its geometry could be affected (except in the sense described by general relativity) either by the motion through it of an observer or other object, or (and this is the important point) by changes in that motion. But that cannot be what you are saying for that is the Lorentzian constructive approach.<br /><br />The question I pose in my paper is this: how are we to comprehend that space is able to contract in one way for one particle and in a different way for another moving relatively to the first, albeit that the two (or at least their correspondingly contracted fields) could be occupying the very same piece of space? <br /><br />If you are suggesting that space does not in fact contract, then we need to ask why it appears that the particle occupying that space is observed to contract. Lorentzian relativity has a simple explanation for this, but in SR there seems a sleight of hand beyond easy comprehension.<br /><br />I tried to raise this problem in a simple way via the “Buzz and Mary” thought experiment in the introduction to my paper. I now ask your forbearance to allow me to include that passage here and would certainly be grateful if you (or anybody else) could explain, as one might in a patient way to a colleague with a less than impressive intellect, where I am in error. <br /><br />Due to size limitations on posts passage follows in new post<br /><br />I then go on to explain how matter would change so as to create this effect, and how this Lorentzian approach brings explanatory advantages, including in particular the provision of a physically reasonable origin for the de Broglie wave.<br /><br />Dan Shanahan<br /><br /><br />Dan Shanahanhttps://www.blogger.com/profile/11240342697478880476noreply@blogger.com