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RAGORDON2010

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About RAGORDON2010

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  1. When I joined this forum, I was hoping for the chance to engage in an intelligent conversation about issues in Special Relativity that have confused new students for decades. Instead, I have found myself talking to walls. So I will be exiting from this forum, but I want to leave three parting thoughts: Thought 1 - Despite how many people say it for other people to hear, despite how many people write it for other people to read, despite how many people key it for other people to link to - The Fact of Nature that the speed of light is the same in all inertial frames plays NO role in explaining the successful application of Special Relatively to solving physical problems! It is a Red Herring! There is another Fact of Nature at work here. What other Fact of Nature? Well, I’ve hidden it in plain sight in Thought 2. Thought 2 - "Slip slidin' away. Slip slidin' away. The nearer your destination, The more you're slip slidin' away." - Paul Simon I've been hoping to offer some thoughts on "relativistic mass" - the notion that mass increases with increasing speed. It's common to come across the statement that accelerating a particle becomes more difficult as particle speed approaches c because "particle mass approaches infinity". I prefer to state the issue differently. I would say that accelerating a particle becomes more difficult as particle speed approaches c because the external field responsible for the acceleration loses effectiveness as the particle speed approaches the speed at which the field mechanisms function. This, of course, offers an explanation for why light speed forms a limiting speed in nature. An old boot can travel no faster through the water than the maximum speed at which the fisherman can reel in the line. Whenever I think about this phenomenon, Paul Simon's song comes to mind. The speeding particle slips and slides away from the grasp of the external field. Thought 3 - I can’t leave this forum without saying something about time dilation. It has always puzzled me that while the physics community easily accepts that time dilation effects in General Relativity relate in some way to the interaction between the time-keeping system and the surrounding gravitational field, the analogous time dilation effects in Special Relativity are viewed as “just so”. Well, I have never cared much for a “just so” story. But I do hold the view that Nature does not care at all for a “just so” story. Something is going on out there! In the most dominant example - the retarded decays of unstable particles moving at speeds close to light speed - I again must fall back on my belief that these effects are in some way a consequence, in ways not at all understood, of the rapid motion of the particles through surrounding electric and magnetic fields. I hold (and this is where Special Relativity exhibits its most severe vulnerability as it is commonly described) that no physical effect can occur as a consequence of merely moving at a uniform speed in an inertial frame of reference. And now, from sunny Alabama (a state in the USA, refer Rand McNally maps, circa 1934), I happily say GOODBYE, Y’ALL!! ROLL TIDE!!
  2. Studiot, I appreciate your attempt to educate me on the history of Special Relativity. We all need occasionally to fill in gaps in our knowledge. However, I have been delving among the ins and outs of SR for maybe 5 decades now, and I'm afraid me ideas are pretty well set. There is a comment of yours, though, that I do wish to expand upon, to wit: [If you only have one frame of reference than you have the difficulty that Fitzgerald (and Lorenz) faced with the results of practical measurements on the propagation of light. This was that the Lorenz-Fitzgerald contraction was introduced as a mathematical formula which accounted for but did not explain the results of these experiments (in particular the Michelson and Michelson -Morley ones) Length contraction of the apparatus arms was a pretty heretical explanation. Einstein on the other hand, deduced the selfsame formulae from purely geometrical considerations of observing the same sequence of events in two frames.] Studiot, I have been "looking over Einstein's shoulder", in a manner of speaking, for some time now, and I want to call your attention to the manner in which he introduces the Lorentz transformations in his1905 original paper. (I have found the English translations of his 1905 papers in the book "Einstein's Miraculous Year - Five Papers That Changed the Face of Physics", Edited by John Stachel and Published by Princeton University Press, 1998, to be particularly helpful.) One almost has to read between the lines, but it soon becomes clear that Einstein is working with a central device consisting of two sticks joined at the ends to form a right angle, one vertical and the other horizontal, with a mirror at the free end of each stick. He also needs a source of light, say, a match. (Please note that there is more than a passing similarity here to Michelson's interferometer.) Einstein imagines that the device is placed in a "moving" frame labeled Frame k with the horizontal stick pointing in the direction of motion. The device is accelerated up to a speed v on the order of light speed and allowed to pass an observer in a "rest" frame, Frame K. When the vertex of the device comes up even with the Frame K observer, the match is struck. The observers in Frame k and Frame K, let's label them Observer k and Observer K, must then measure the times for the light rays emanating from the match to reach the two mirrors and the times for the reflected beams to return to the vertex of the device. As Einstein describes events, it appears that Observer k has the easier task. It is as if she struck the match. In fact, it's as if she is not moving at all. As she perceives the rays, one travels straight up to the vertical mirror and the reflected ray returns straight down to the vertex, the other ray travels in a straight line to the horizontal mirror and the reflected ray exactly retraces the path and returns to the vertex. Observer K has the more difficult task. It is as if he struck the match. As he perceives the rays, they must catch up to the moving mirrors, and the reflected rays must then meet up with the moving vertex. Einstein now sets out to demonstrate that the data obtained by the two observers satisfies the Lorentz transformations. In other writings, I have described Einstein's analysis as "unnecessarily and uncharacteristically opaque". After plunging into the depths of an argument that I have never been able to parse, he finally breaks through the surface of the water proudly holding in his hand a Lorentz-Fitzgerald contracted horizontal stick as perceived only by Observer K. I have often wondered why the editors of the journal where this work was published didn't insist that he take a clearer approach in his analysis. I do intend to suggest one possibility in a future post, but there is no avoiding his conclusion that the horizontal stick as perceived by Observer K is Lorentz-Fitzgerald contracted. This is Michelson-Morley all over again! Nothing new here! That Einstein was able to proceed from this point and create his magnificent Special Relativity Theory is a tribute to his genius.
  3. I too have been a teacher at various points in my life and, if on any given day, I found that I had held the attention of my students, prodded their curiosity, and possibly stimulated their imagination, I went home that night feeling that I had a very good day. I would imagine you have had days like that also. Teaching is not easy, particularly as the ideas become more abstract and removed from the students' day-to-day experiences. That's one reason I feel there is value in giving students alternative ways to view a problem. and the conceptual problems posed by Special Relativity definitely could use an alternative viewpoint. And if this viewpoint is grounded in their sense of two separate experiments conducted in the same laboratory, I believe a that good number of students would benefit from this viewpoint and find that they would be more open to arguments drawn from the conventional viewpoint of one experiment and two laboratories moving uniformly relative to each other at near-light speeds.
  4. Lately, I’ve been using “Special Relativity and Classical Field Theory”, Leonard Susskind and Art Friedman, Basic Books, 2017, as a desk reference. They state on p.57 that “proper time” and “spacetime interval” are negatives of each other, each referencing spacetime distance. I have no citation I can give you regarding the Einstein-Minkowski story. It may be apocryphal.
  5. Studiot, you are becoming one of my favorite responders because you seem to have a knack for leading me into areas I very much want to address. I am aware that Hermann Minkowski first dealt with the problems of the 4-space of t,x,y,z, i.e. "spacetime", circa 1908. His concern was how to specify a "distance" or separation between two spacetime events by building on Einstein's special relativity theory. This separation we now refer to as "proper time". I will have much more to say on Minkowski's contribution in later posts. It is worth noting here that, as the story goes, when Einstein first became of aware of Minkowski's paper, he mumbled something about mathematics muddling up good physics. (Hmm.) By "change of viewpoint" in the context of Special Relativity, I am working at a higher level of abstraction than simply relative velocities as seen by moving observers. This is what I am talking about - "We have, on one hand, the conventional scenario consisting of a single experiment and two inertial frames of reference in uniform relative motion and, on the other hand, an alternative scenario consisting of a single frame of reference and two separate but related experiments". (And, please, forget I ever mentioned the Earth and the Moon.)
  6. I apologize for confusing you with my initial remarks. I hope you will see that I've tried to be more specific in my later posts. The Earth to Moon imagery was just a way of letting the readers know that I was going to present a change of viewpoint.
  7. Thanks to all of you who have taken time to respond to my posts. The subject of Special Relativity deserves all the attention it gets. I think I’ve stumbled onto some sort of DNA test among followers of SR. We have, on one hand, the conventional scenario consisting of a single experiment and two inertial frames of reference in uniform relative motion and, on the other hand, an alternative scenario consisting of a single frame of reference and two separate but related experiments. I hold the view that both scenarios should be introduced and discussed in high school junior and senior science classes and also at the freshman university level. Let the students choose their preference according to their natural inclinations. Obviously I have my own preference but, particularly with the advent of General Relativity, the question of relationships across multiple reference frames becomes significant and must be introduced and discussed. Which brings me to the subject of scenario equivalence. Let me give an example. I pose the following question - Without invoking the mathematics of the the Lorentz transformations, is there a way to match an observation by observers in one reference frame with an observation by observers in the other reference frame? I believe Einstein wrestled with this question because he introduced the notion of the “mutually observed light flash” - a match is struck and the light flash is observed instantly by observers in both frames. Beginning with the conventional scenario, let’s not just talk about it - let’s do it, at least in thought. Let’s go back to the situation where I stand on the platform and you are on the speeding train along with the charged ball. This time, however, I want to insert a small firecracker inside the ball. Then, once the ball starts looping as I perceive it, and hopping as you perceive it, I zap the ball with a laser beam and set off the firecracker. Pow!!! The ball explodes at an object point (t,x,y,z) in my frame and at the corresponding image point (t’,x’,y’,z’) in your frame, where the object-image coordinates satisfy the Lorentz transformations. Obviously, I cannot reproduce this match-up in the related experiments scenario. I think what we have here might be what theoretical physicists refer to as a “broken symmetry”. It certainly looks like a broken symmetry to me. (Actually after re-reading the above text, I did indeed find a way to match up observations across related experiments, and I’ll describe it in a future post. In my next post, however, I want to discuss time dilation and “slow clocks”.)
  8. Hi. Thanks for your post. You're right - all inertial reference frames are equivalent for illustrating physical laws. However for a long time, I have believed that the train stories cloud the importance of Special Relativity for our young high school juniors and seniors and college freshmen struggling to understand how physics challenges their intuitive understanding of how Nature works. That's why I have long advocated for the related experiments approach to teaching the subject - one fixed frame of reference and two separate but related experiments, as opposed to a single experiment and two frames of reference in uniform relative velocity (moving at speeds close to the speed of light, no less). Just a cursory review of questions students ask about slow clocks and shrinking meter sticks illustrate the depth of the confusion. In the related experiments approach, there are only one set of clocks, one set of meter sticks and, of course, one set of whatever additional laboratory apparatus is needed. My clocks do not run fast or slow or whatever, my meter sticks do not shrink or grow or whatever, etc. In my Monday/Tuesday imagery, I only flip a page on the calendar. Let me give you an example of how confusing things have gotten: Given a pair of spacetime coordinates (t,x,y,z) and (t’,x’,y’,z’) connected to each other by a Lorentz transformation - The conventional view: Two reference frames, Frame O and Frame O’, moving uniformly relative to each other, locate the SAME point in spacetime, where the first set of coordinates are specified by the clocks and meter sticks belonging to observers in Frame O and the second set of coordinates are specified by the clocks and meter sticks belonging to observers in Frame O’. The related experiments view: There is a SINGLE frame of reference in which a pair of related experiments are carried out - the first, say, on Monday, and the second on Tuesday - and where the two sets of coordinates identify SEPARATE points in spacetime. These points appear on the separate world lines produced by the experiments, or, in 3-space, on the separate paths of motion. Look, Einstein was fully aware of the fact that Maxwell's equations hold their form under a Lorentz transformation. Had he built on that observation and created a related experiments picture along the lines discussed here, we would stiil have Einstein's Theory of Special Relativity, but without the nonsense. As things stand today, the conventional view offers a weird, confused, unintuitive and abstract reach for reality. In contrast, the related experiments view is reality.
  9. At the risk of wandering into the dreaded realm of Speculation, I wish to offer the following insight into Special Relativity. To help put you in a proper frame of mind for this offering, imagine standing on the earth and looking UP at the moon. Now imagine standing on the moon and looking DOWN at the earth. It's just a difference in viewpoint. To begin, we will go earth to moon: Imagine I am standing on a platform next to a train track, and you are on a train speeding past me at 0.8c. I apply a magnetic field across the track, and a charged object, say a ball, riding with you in your train gets caught up in this field. What happens? I will see the ball looping in a vertical plane. You will see the ball undergoing a serious of weird pogo stick hops and until it hops out the back door of your train. The Lorentz time and space transformations relate my measurements of the path of motion (t,x,y,z) for the looping ball to your measurements of the path of motion (t',x',y',z') for the hopping ball. Now let's go moon to earth: Imagine I set up the following experiment in my laboratory on a Monday - I accelerate the charged ball up to 0.8c, and expose it to the same magnetic field. I will see the ball undergo the same looping motion that I observed in the train situation. On Tuesday, I place the ball at rest on a table and apply the combination of electric and magnetic fields that your equipment measured in the train situation (i.e. the image fields produced by applying the Special Relativity field transformations to the magnetic field I applied across the track). In this case, I will see the ball undergo the same hopping motion you observed in the train. My observations (t,x,y,z) of the path of motion of the ball in Monday's experiment will map over to my observations (t'x'y'z') of the path of motion of the ball in Tuesday's experiment via the same set of Lorentz transformations, only here the initial velocity of the ball in the Monday experiment is playing the role of the relative velocity between train and platform. What we have shown here are pairs of object-image observations arising from a pair of object-image "related experiments". Nothing new here. Object-Image experiments are useful for illustrating symmetries in natural laws.
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