Ballistic Theory, Progress report...Suitable for 5yo Kids
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From: George Dishman on 11 Sep 2005 10:40 <jgreen(a)seol.net.au> wrote in message news:1126405408.815651.120520(a)f14g2000cwb.googlegroups.com... > > Jeff Root wrote: >> Jim Greenfield replied to Jeff Root: .... I was really just going to ask about the comment to me at the bottom but since this is rehashing an old conversation with Jim, I'll refresh his memory. >> >> > when train is in motion, by ANY analysis, the ray's direction >> >> > is ALTERED- it no longer strikes center. >> >> >> >> Relative to the world outside the railcar, the ray's >> >> direction is altered. Of course, to a person on the >> >> railcar, not knowing whether the car is moving, or in >> >> which direction or at what speed, the ray's direction >> >> is not altered-- it is still going from the ceiling >> >> straight down to the floor. .... and the Earth is moving sideways (whether he knows it or not). >> > Hooray!!!!!!This is what I have been saying on this group >> > forever; that the observers MAKE MISTAKES!!!!!! Because the >> > train rider is denied the information about the REAL situation >> > (being able to know that he is moving), he is MISTAKEN/TRICKED >> > as to the true situation. >> >> What gives you the idea that the person on the train has >> been tricked or is mistaken about the true situation? >> He sees the light go from the ceiling straight down to the >> floor, and that is exactly what happens. > > Rubbish! Read above again to realise that he IS mistaken- and I can > prove it! Cut a hole in the floor, and where before the train rider was > SURE that the beam is vertical, he actually finds out that he was > mistaken/WRONG, when he sees the beam MISS the eaths centre (flat > earth) We went over this many times Jim but you seem to have forgotten it all. In the scenario where the train is moving, the Earth is moving sideways (inertial motion) with the centre directly below at the moment the light is emitted so he also expects the light to miss the centre. >> If he doesn't know whether or how the railcar is moving >> relative to the Earth, then he doesn't know where the light >> beam will go relative to Earth's center. He will only be >> mistaken if he *thinks* he knows how the railcar is moving >> relative to the Earth, but is wrong. I'm sure that isn't >> the scenario you're interested in. > > It certainly is! The passenger thinks he is ststionary ref the line at > all times, and THAT is why he thinks the beam is VERTICAL at all times. > Give him the true situation/information, and he deducts the truth. He IS stationary and the light IS vertical as measured by him, it it the Earth that is moving. That is his "truth". > NB that I don't make claim as to what he SEES; ... All of us I hope are correcting for illusions that would be caused by the finite light travel time, we really should be past that sort of diversion. >> >> > FYI, this is a CHANGE IN VELOCITY; not only in direction, >> >> > which is integral to velocity, >> >> >> >> Yes the velocity has changed, but only in direction. >> >> The magnitude of the velocity (speed) is unchanged. > > Then it will take longer to reach the floor, as it is travelling a > LONGER path. Or doesn't v=d/t?? "d" and "t" as measured by the passenger gives v=c. > When I have more time, I will get back to George with his animation, > and see what he can come up with if his clocks tick together, rather > than assuming that one WILL do more ticks (no offence George) I don't know why you think I would take offence when the work I had done was correct, merely unfinished. However, which graphic are you talking about, the one in which the clocks tick simultaneously illustrates Galilean relativity so the speed of the light is not c, while the other illustrates SR, the clocks do not tick at the same coordinate rates and the speed of light is c on all frames as we observe. George
From: Jeff Root on 11 Sep 2005 11:02 Jim Greenfield replied to Jeff Root: >> >> > With train stationary, ray from ceiling would strike earth >> >> > center; >> >> >> >> OK-- You're talking about a light ray going from the ceiling >> >> of a railcar straight down to the floor, and beyond. >> >> >> >> > when train is in motion, by ANY analysis, the ray's direction >> >> > is ALTERED- it no longer strikes center. >> >> >> >> Relative to the world outside the railcar, the ray's >> >> direction is altered. Of course, to a person on the >> >> railcar, not knowing whether the car is moving, or in >> >> which direction or at what speed, the ray's direction >> >> is not altered-- it is still going from the ceiling >> >> straight down to the floor. >> > >> > Hooray!!!!!!This is what I have been saying on this group >> > forever; that the observers MAKE MISTAKES!!!!!! Because the >> > train rider is denied the information about the REAL situation >> > (being able to know that he is moving), he is MISTAKEN/TRICKED >> > as to the true situation. >> >> What gives you the idea that the person on the train has >> been tricked or is mistaken about the true situation? >> He sees the light go from the ceiling straight down to the >> floor, and that is exactly what happens. > > Rubbish! Read above again to realise that he IS mistaken- and > I can prove it! Cut a hole in the floor, and where before the > train rider was SURE that the beam is vertical, he actually > finds out that he was mistaken/WRONG, when he sees the beam > MISS the earth's centre (flat earth) You are still failing to think the problem through. I know that because you are leaving out several key pieces of your argument. Without those pieces, your argument doesn't have any conclusion. It isn't an argument at all-- just a set of statements about a scenario, which don't make any point. Let me start with the least important bits, mainly to show that you are in fact leaving things out. You suggest parenthetically that Earth can be considered flat for this thought experiment. I'm pretty sure that the reason you suggest it is the fact that on a spherical Earth, the train has to move in a circle, so the direction of "down" changes constantly, and you wanted to avoid that complication. Obviously, a flat Earth has no center, so your scenario would be lost. But all of that is irrelevant to your problem. The only function of Earth's center in this thought experiment is as a reference point separate from the train. The Earth itself is irrelevant to your thought experiment. The train could be replaced by a spacecraft, and Earth's center replaced by a lost sock flying through space at some distance from the spacecraft. That scenario is completely equivalent to yours. However, I'll stick with your train scenario. Rather than suggesting a flat Earth, you could specify that the experiment takes place over a short distance, so Earth's curvature isn't a factor. We can still presume that Earth's center is a mathematical point, so any motion of the train will cause the light beam to miss it. The second relatively unimportant bit is the business about cutting a hole in the floor. You never say why the hole is made. You never say how the hole is used. You never say that the observer looks through the hole or makes some measurement through it, and you never say what he sees or measures. It is a gaping hole in your argument. It forces me to make part of your argument *for* you! Now something more important you left out. You claim that "the train rider was SURE that the beam is vertical". Apparently you meant vertical relative to Earth. You didn't say that, so I have to do your work for you and guess. The experimenatal setup specifies that the light beam goes straight "down" from the ceiling to the floor, so, relative to the railcar, the beam obviously *is* vertical. So you must mean relative to the Earth. Next, WHY was the train rider sure the beam was vertical relative to the Earth? You didn't say. What observation was his belief based on? You didn't say. If the rider could not see outside the car, and had no knowledge of whether it was moving or not, then surely he would know that he could *not* know whether the beam was vertical relative to the Earth. Do you agree? If the rider *could* see outside the car, and measure its motion relative to the earth, then he would be able to correctly determine whether the beam was vertical relative to the Earth. Do you agree? >> If he doesn't know whether or how the railcar is moving >> relative to the Earth, then he doesn't know where the light >> beam will go relative to Earth's center. He will only be >> mistaken if he *thinks* he knows how the railcar is moving >> relative to the Earth, but is wrong. I'm sure that isn't >> the scenario you're interested in. > > It certainly is! The passenger thinks he is ststionary ref the > line at all times, and THAT is why he thinks the beam is VERTICAL > at all times. What "line"? This is the first mention of a "line". If by "line" you mean the light beam, then the passenger *is* stationary wrt the light beam at all times. If by "line" you mean a line from the light source to the center of the Earth, then, again, the passenger *is* stationary wrt that line at all times, if the train follows the curve of the Earth. But you imply (without saying) that the passenger thinks the line is stationary wrt the Earth. Why would he think that? You didn't say. I see no reason for him to think that the line is stationary wrt Earth. > Give him the true situation/information, and he deducts the truth. I agree with that! > NB that I don't make claim as to what he SEES; the ray NEVER > strikes the eye of any observer in this dendanken- To determine whether the beam hits Earth's center, just put a photocell down there. That's no problem. > the whole idea is based on the assumption that c=c+v BEFORE > the clocks are started (they are not ticking in sync) As you pointed out at the start (September 6), there are NO clocks in this thought experiment. So this comment appears to be completely irrelevant. If it has any relevance, you didn't say what it is. >> > He can easily get it right by drilling a hole in the floor, >> > and coming back later to see where the ray ACTUALLY was headed >> > when the train was in motion. >> >> Or by looking out the window and seeing how the train is >> moving relative to the Earth. He's smart enough to realize >> that if he doesn't know how the train is moving relative >> to the Earth, he can't determine where the light will go >> relative to the Earth. Duh. >> >> > Must we be condemned to believe a falsehood about light >> > propagation forever, because the passenger has the WRONG >> > information, and reaches the WRONG conclusion???????/ >> > Not yours t! >> >> You need to think about the scenario more carefully. >> >> >> > FYI, this is a CHANGE IN VELOCITY; not only in direction, >> >> > which is integral to velocity, >> >> >> >> Yes the velocity has changed, but only in direction. >> >> The magnitude of the velocity (speed) is unchanged. > > Then it will take longer to reach the floor, as it is > travelling a LONGER path. Or doesn't v=d/t?? The passenger, stationary wrt the light beam, finds that the light takes the same amount of time to reach the floor nomatter how the train is moving relative to the Earth, since it is always travelling the same path: from the ceiling to the floor. An observer stationary wrt the Earth finds that the light takes longer to reach the floor when the train is moving, because the light travels a longer path, as you say. You think that the observer on the Earth is right, and the observer on the train is wrong. Imagine that the train is on a planet orbiting a distant star. The train is stopped in the station, but the planet is moving with enormous speed relative to Earth. Using the SuperMegaHyperTelescope at the top of Mount Everest to view inside the train, we see the light beam travel from ceiling to floor on a long diagonal path. It takes the light ten nanoseconds to cover that distance. Yet to the person on the train, it takes only seven nanoseconds, since it is going straight down from ceiling to floor. Which observer is right, and which is wrong? Think about it. >> > Yep! That amazing bulb again, which gives each and every >> > emitted photon instruction on which 'speed' to leave at, >> > according to whether it is headed forward, down, or >> > otherwise. haha >> >> >> >> > but geometry (pythag) will give the conversion to the >> >> > changed photon propagation. >> >> >> >> I'll let you explain what you had in mind when you wrote >> >> that, rather than trying to guess. >> > >> > A photon emitted directly forward will have velocity c+v >> > Others will be subject to vector calculations. Get it now? >> >> No. Show the geometry and the numbers. Say what you have >> in mind instead of just making vague allusions to what you >> have in mind. >> >> >> > NB: no clocks here! or do you wish to call on the photon's >> >> > inate sense of the train's speed, and alter it's expulsion >> >> > speed from the globe? (Which must be different from those >> >> > directed in each different direction lol ) >> >> >> >> Again, I'll let you explain what you are talking about. >> > >> > Done and dusted to those who escaped the AE brainwash >> >> My hope was that you would explain why you think the light >> must be moving at different speeds in different directions. >> It seems obvious that it must move at different speeds-- >> until you try to explain it. You haven't done that. > > The hypotenuse ceiling to floor is LONGER than the vertical. Relative to the Earth, but *not* relative to a person on the train. > Therfore, unless the photon is moving at different d/t along > those paths, they wouldn't hit floor simultaneously. You say "the photon is moving" (singular), and "they wouldn't hit... simultaneously" (plural). I can't tell what things "they" refers to. You clearly are talking about multiple things, but what? If you mean that the observer in the moving train and an observer stationary on the ground could not see a light pulse from the ceiling of the train hit the floor at the same time, that depends on where the stationary observer is located. If he is right beside the train when the light reaches the floor, then both observers will see the light hit the floor simultaneously. If he is anywhere else, he will see it hit the floor later than the person on the train. However, I don't think the time lag is what you are interested in. You are interested in the length of time it takes the light to go from ceiling to floor. The observer on the ground sees the light travel a greater distance, and therefore take a longer time to reach the floor. > This is too repetitive- you either get it or not. I get it. You need to think about it more. Here is an important question: What do you think Einstein's special theory of relativity is about? Equivalently, why do you think it exists? Why did Einstein work it out, and why was it accepted by other physicists? You may have an answer to that question which is different from mine, so here is an even more important question, which I really hope you will answer: What do George and I think Einstein's special theory of relativity is about? Equivalently, what reason would George and I give to the question of why it exists? How would George and I answer the question of why Einstein worked it out and why it was accepted by other physicists? > When I have more time, I will get back to George with his > animation, and see what he can come up with if his clocks > tick together, rather than assuming that one WILL do more > ticks (no offence George) You don't understand what the animation shows. If you did understand *what* it shows, you would understand *why* it shows what it does. -- Jeff, in Minneapolis
From: Henri Wilson on 11 Sep 2005 17:39 On Sat, 10 Sep 2005 14:03:20 +0100, "George Dishman" <george(a)briar.demon.co.uk> wrote: > >"Jeff Root" <jeff5(a)freemars.org> wrote in message >news:1126290183.817714.111790(a)z14g2000cwz.googlegroups.com... >> Henri Wilson replied to Jeff Root: >> > >>>>>>>> The Sagnac experiment shows that the BaT is wrong. >>>>>>> >>>>>>> Dishman told you that. >>>>>> >>>>>> No, George *showed* *you* that. I followed the entire >>>>>> discussion between the two of you. I followed George's >>>>>> explanations and arguments. I understood them, and what >>>>>> they imply. >>>>> >>>>> George is wrong. In a four mirror sagnac, the source and >>>>> mirrors are moving at 90deg wrt the frame of next mirror. >>>> >>>> The source and mirrors are not moving at all relative to the >>>> frame of the next mirror. >>> >>> No wonder you are not a physicist..... >> >> I responded to what you said. What you said was not what >> you meant. >> >> What you *meant* was: In a four mirror Sagnac, the source >> and mirrors are moving at 90deg wrt the next mirror, in the >> frame of the lab. >> >> In the frame of the next mirror, the source and other >> mirrors are not moving at all. Galilean relativity, pure >> and simple. > >In a frame whose origin is the next mirror and >which is rotating with the table, Jeff is correct. > >In a frame whose origin is the next mirror but >which is not rotating, i.e. the origin is merely >translating with the mirror, then the source is >moving in a circle about the mirror. Why anyone >would want to use either of those frames is not >apparent to me but as we know, all frames must >give the same predicted measurables so Henri can >try those if he wishes. The analyses will be more >complex because a lot of symmetry is lost. > >>>>> It certainly does NOT disprove the BaT. >>>> >>>> George showed exactly how and why it disproves the BaT. >>>> You didn't like the result; You rejected the result; You >>>> speculated about some problems you think it must have. >>>> But those speculations have no basis in fact. Their only >>>> basis is in your dislike of the experimental results. >>> >>> George was wrong. >>> He thought that during rotation, the source moves towards the >>> next mirror. It doesn't. It moves at right angles to it. >> >> I'll let George respond to that, if he wants to. > >I thought no such thing, I have no idea how Henri >came to that conclusion. There are only two frames >I have ever used in serious analysis, an inertial >"lab" frame with origin at the centre of the table >and the non-inertial "co-rotating" frame which also >has the origin at the centre of the turntable but >is rotating at the same speed as the table. It is >obviously the speed of the light that affects the >time taken, not the speed of the mirror. > >In the former frame, for v<<c and a square setup >(three mirrors and the source/detector), the speed >of the light according to Ritz would be: > > v' = c +/- v/sqrt(2) Consider a single photon. When it is emitted, it has the above component velocity in the direction of the next mirror AT THAT INSTANT. However the next mirror will move before the photon reaches it. The component in the direction of the mirror WHEN THE PHOTON ARRIVES is not described by the above equation. >where v is the tangential speed of the source and >mirrors, v' is the speed of the light and c is the >usual constant. The "+/-" factor accounts for the >two beam directions. The factor of 1/sqrt(2) is >because the light is launched at 45 degrees to the >motion of the source. In general for an N point >path (N-1 mirrors), the formula is: > > v' = c +/- v * cos(pi / N) > >You can't give a single value for the speed in the >frames Henri is discussing because it varies as the >light progresses around the path. > >Again, it is perhaps more informative to turn it >around. Comparing the output signal with the known >speed of the turntable allows the speed of the light >beams to be measured (assuming only that the speed >increment is symmetrical) and the result is v' = c, >not as shown above. > >I think the reason Henri keeps tossing in these vague >hand-waving arguments is that he has come to realise >that every quantitative analysis gives the same null >result under the Ritzian model. Turning a blind eye >is all he can do now. It is not related to light speed at all. The sagnac effect is caused by the fact photons have an 'axis' and that axis wants to remain in the same direction. When a photon is deflected from a moving mirror, the axis rotates slightly. Two meeting beams whose axes are not aligned can produce interference fringes in much the same way as two beams of unequal path lengths. > >George > HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: Henri Wilson on 11 Sep 2005 17:43 On Sat, 10 Sep 2005 10:47:58 +0100, "George Dishman" <george(a)briar.demon.co.uk> wrote: > >"Henri Wilson" <H@..> wrote in message >news:ekv3i1t1db9sqkpui1oj6082v1norhgdu4(a)4ax.com... >> On Fri, 9 Sep 2005 10:16:12 +0200, "Harry" <harald.vanlintel(a)epfl.ch> >> wrote: >> >>> >>>"Henri Wilson" <H@..> wrote in message >>>news:jcd1i11abmioioqoc2ccunab9n2pubil28(a)4ax.com... >>>> On Thu, 8 Sep 2005 09:54:55 +0200, "Harry" <harald.vanlintel(a)epfl.ch> >>>wrote: >>>> >>>> > >> >>>> >at all. Thus ballistic light should move with constant speed wrt the >>>> >fibre - >>>> >if not, why not? >>>> >>>> Forget the fibre version. ...It's like integrating 0/0. >>> >>>It's the most simple and straightforward according to me, and your >>>argument >>>sounds blurry... > >When we started talking about Sagnac, Henri said >using fibre was simply a case of total internal >reflection like a standard table but with an >infinite number of mirrors and he was right of >course. The only reason he is backtracking is >because the analysis in the rotating frame is >trivial as you say and unarguably shows Ritzian >theory to be untenable. only when the wrong equation is used..... > >> It's too hard for you. > >What Henri means is that he wants everybody to >"forget the fibre version" because he has no >argument against it. My attitude is that the fringes are not casued by path length difference at all. They are a consequence of the fact that the two beams are not parallel when they meet. > >George > HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: Jeff Root on 11 Sep 2005 18:16
Jim Greenfield wrote: > Cut a hole in the floor, and where before the train rider was > SURE that the beam is vertical, he actually finds out that he > was mistaken/WRONG, when he sees the beam MISS the eaths > centre (flat earth) My apologies. I said that you hadn't specified what the person on the train would do with the hole in the floor, but you *did* say that he sees the beam miss the Earth's center. We already knew that, though, so it added nothing to the thought experiment. -- Jeff, in Minneapolis |