And just for a link cause I was basically recounting a textbook. https://www.google.com/search?clien...IABAIgBAJIBAJgBAKoBB2d3cy13aXo&sclient=psy-ab
Here are Einstein's own words, from his 1905 paper On the Electrodynamics of Moving Bodies link provided below: "If at the points A and B ... there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B..." https://www.fourmilab.ch/etexts/einstein/specrel/www/
I am working on it....Please Register or Log in to view the hidden image! Question: If time stands still @ "c", why does it take 1 second for a photon to cover 386,000 miles? What slows the photon down from "c" for time to not completely stop?
1. Time does not "stand still" at c. If you try and plug c into the time dilation formula, you get 1/0, which is undefined. 2. Even if this were not the case and you assumed that a clock moving at c "stopped". All this means is that for someone that the clock was moving at c with respect to, that clock would take an infinite amount of time to tick off any given amount of time ( for this observer, the clock hands would be frozen at one reading). But this has nothing to do with time it takes for this observer to measure the clock covering a given distance at c.
Write4U; After reading a few pages of your posts, I see a need for clarification concerning time dilation (td). Td is not just about clocks, but about specific em processes. The light clock is one example that is easy to understand due to it's simplicity, with light reflecting from a mirror and counting the cycles. If the clock moves, the light has to intercept a moving mirror. Since light speed is constant and independent of the speed of the emitter, it must move in 2 dimensions with a horizontal speed component that compensates for the clock motion. That means the vertical speed component is reduced, and requires more time on the clock to reach the mirror. A marksman shoots ahead of the moving target expecting the target and shot to collide. This describes the clock process. Biological/chemistry processes, include em transactions, thus biological processes also occur at a reduced rate when the life form moves at high speed. If the emitter and mirror are replaced with 2 particles, exchanging photons, as the pair move at high speed, their rate of interaction slows, showing td to apply all levels of physics. Radioactive decay is considered to be a process (understood or not), thus the rate of decay would be expected to slow for high speed particles, such as muons. Experiments from the 1960's on have verified this phenomena for various 'fundamental' particles. The point is, td relates to processes involving composite objects with a rate dependent on speed. The speed of light c, is constant in space/vacuum, and only varies in materials of varying density. Speed causes td, so td does not affect speed.
Thank you for your indulgence. I am getting a clearer picture, but I still have a question. From my earliest recollection of the "man in the elevator", this was not at all as represented by the example of a photon gun inside a moving elevator, shooting at a relatively stationary target, mirrors which will then reflect the photon and measure the flight of the photon while the elevator is accelerating and create a zig-zag pattern in spacetime? A wave function? From what POV is that phenomenon recorded. From the outside observer or the inside observer? To me that all sounds as a lot of smoke and mirrors. Surely this is not what Einstein had in mind when he tried to demonstrate the effects of gravity. I believe he presented the man in the elevator as 2 separate sub-experiments (1 stationary, 1 accelerating.) as I submitted with illustration. Let me try to use your marksman observer example. What I see in this thought experiment is, that the marksman (observer) is; a) outside the elevator and does not move at all. He is the marksman observer, relatively stationary to the spacetime coordinates of the stationary elevator as well as for the instant of the passing accelerating elevator. The gun is never adjusted and shoots at regular intervals from the same distance outside the elevator in both scenarios, at the measured shortest distance between the elevator walls @ 90 degree angle, regardless if it is stationary or accelerating. b) only relative to the reporter (observer) inside the accelerating elevator and be subject to all kinds of things happening because he is the one in motion and all his measurements are relative to the baseline stationary marksman and his firing of photons at any arbitrary regular interval and the spacetime coordinates at which all this is occurring (laboratory?), no? The photons never move at all, each shot is identical to all the other shots and all the photons follow the exact straight path to the opposite wall. The elevator and every thing in it, moves relative to the photons. My question is if the measurement made by the marksman (stationary baseline) from the outside are different from the measurements made by the reporter from the inside, and how ? The illustration I provided is the one I recall as the original Einstein thought experiment. All the other variations came later and I'll accept their conclusions. But as presented, it seems to me they disagree with Einstein's original model in several respects. As I understood it, the light beam always always hits the other side at exactly the same time regardless of the movement by the elevator, accelerating, or steady movement, or stationary. I believe this is a very different scenario as in the horizontal experiment involving mirrors
Write4U; The man in the box/elevator: On the left, an observer (square) in the box is propelled upward experiencing 1 g of acceleration. Simultaneously, light enters from the right wall moving horizontally to the left wall. The perception of the observer is, the light moves downward a distance y as it crosses the interior. On the right, Einstein then places the observer in a box resting on the ground experiencing 1 g from gravity. Since the observer has the same acceleration experience in each box, Einstein predicts that light should follow a curve in a g-field. I.e., the physics is the same regardless of the source of acceleration. The prediction was verified in the solar eclipse of 1919. Light speed was c for the duration of the experiment. The rule is: observer motion cannot alter distant events, but it does alter observer measurement and perception. Please Register or Log in to view the hidden image!
Questions; a) Was there a difference in time between the stationary and the moving experiments? b) Was there a red-shift for the curved portion of the light or was it the same as for the straight portion?
Write4U; If you research 'Pound-Rebka experiment', it will explain the doppler shift effects on light moving vertically in a g-field. The clock rate depends on its height above the earth surface, the higher the faster.
Yes. I have no quarrel with any variations . But I am only addressing Einstein's "man in the elevator" experiment. The Einstein man in the elevator experiment is not about doppler effect. It is all the variations which yield all these different results depending on the FoR. Yes, in all the other experiments. Einstein's thought experiment is performed in a vacuum, where the elevator is accelerating upwards. What I understand from the narratives, Einstein's experiment is based on the reporting by the person inside the elevator and demonstrates the relative effects of gravity as reported by the observer and not necessarily of time, which does not vary whether the line of sight is straight or curved. The photon gets to the other wall at the same time in both scenarios. It is the observer which experiences the relative effects.
This is an invalid statement. Since no clock can be present at both the light being emitted from one wall and being detected at the other, the elapsed time between those two events is frame dependent. The presence or absence of observers doesn't change this. From inside the box, there's not an obvious way to express the elapsed time.
I don't think you are ready for any thought experiment involving acceleration or gravity. In the light clock video that I had linked to in post #79, the moving clock moves at constant speed, it does not accelerate. That should be easier to understand than one involving acceleration. Yet you had considerable difficulty understanding the implications of that video. The first thing I think you should do is to come to terms with the idea of reference frames. We have to specify a reference frame when we ask how much time elapses between two events. In the video animation that I linked to in post #79, the reference frame that we are considering is the one in which the LEFT light clock has a velocity of zero. That is because the animation's video camera which is supposedly recording that video also has a velocity of zero in that frame. So we can measure how far something travels by how far it travels on the animation screen that we are watching. Now, using only the reference frame in which the animation's video camera has a velocity of zero, do you acknowledge the following are true? 1. The light inside the LEFT light clock travels a shorter distance per tick than the light in the RIGHT light clock does. 2. The shorter distance light path in the LEFT light clock will allow it to accumulate more ticks, while the longer distance light path in the RIGHT light clock will cause it to accumulate fewer ticks, for the duration of the animated video. (Bear in mind that the speed of light in both clocks is the same, unlike a bouncing ball on a moving train, which would 'inherit' the speed of the moving train, according to an observer watching the train pass by.)
I already have indicated my agreement with all variations of time measurement, but that is not what Einsteins man in the elevator addresses. Why don't you address the man in the elevator experiment exactly as it was devised? Why do you insist on pushing your version on me. I have no quarrel with that at all.
Sorry I must have missed the post where you agreed that the moving light-clock elapses fewer ticks than the stationary light-clock in the animation that I linked to. Immediately after I posted it, you started telling me it was wrong, and that both clocks must remain synchronised, and that the path of light in the moving clock was really up and down, not diagonal, etc. I'm glad to hear that you have come around now. I haven't addressed the elevator thought experiment because it involves acceleration, and is therefore more complicated than the one I posted about. I would rather make sure you understand the simpler thought experiment, rather than move on so quickly.
I'm new to this thread, but thought I'd comment on a few loose ends. That's incorrect. In the gunner's reference frame, the bullet has a velocity in, say, the x direction. In the target's reference frame, as he is stepping aside, the bullet has two components to its velocity: a velocity in the x direction and a velocity perpendicular to that (call it the y direction), with the y component being equal to the target's "stepping aside" speed. The total speed of the bullet is then $\sqrt{v_x^2+v_y^2}$, which is, of course, greater than $v_x$ alone. So, the bullet does have two speeds at the same time: a different speed in each frame of reference. But you already know this is possible. Drive along the highway in a car. The car driving along beside you in the lane next to you has zero speed relative to you, but it has a speed of 100 km/hr according to a guy standing on the roadside watching the two of you go past. So, that car has two different speeds "in reality" at the same time.
Yes. But realise that this is completely contrary to what you'd expect to see in a non-relativistic universe. In that case, to get the speed of the light in a different frame, you'd need to add (or subtract) the speed of that frame to c, just like in the gunner and car examples I discussed in the previous post.
The example of the muons in the box from the crank website is wrong, for a subtle reason. The idea is okay: start with equal numbers of muons in two boxes, then compare the numbers at some later time (e.g. when the sky box reaches the ground). Here's what happens: In the ground frame, the muons in the sky box decay more slowly, so when that box reaches the ground there are more muons in the sky box than in the ground box. It is also true that in the sky box frame, the ground muons decay more slowly than the sky muons, but it is still the case that when the two boxes meet at ground level (i.e. when the ground comes up to meet the sky box) the sky box observer will say there are fewer muons in the ground box than in the sky box. How can this be? The question that needs to be asked is this: when was the number of muons the same in each box? (This was the starting condition, remember.) The problem (and the solution to the apparent paradox) is that events that are simultaneous in the ground frame are not simultaneous in the sky box frame. In other words, if the ground observer says the number of muons in both boxes was the same when the sky box was at the height of Mount Everest, then the sky box observer will say that at the instant Mount Everest was flying upwards past the sky box, the ground box did not have the same number of muons in it as the sky box; in fact, at that time in the sky box frame, the ground box already had fewer muons in it than the sky box. The key term that solves this problem - the term that the writer of the crank website doesn't understand - is "relativity of simultaneity".
Thanks for that explanation. It makes sense, the way you present it. However I have one question. How many boxes are actually being measured simultaneously? If we start with only one box in the sky, it must contain the same muons for both observers, no? And when that box hits the ground, the number of muons is also the same for both observers, no? If I understand the experiment correctly, at no time are there two boxes with muons in them, which would allow for simultaneous observational comparison. I understood that the "expectation" of decay is not satisfied and appears to deliver an unexpected number when reaching the ground. And that might well be explainable in theory. Not trying to be difficult, but very interested in any "unexplained" phenomena.....Please Register or Log in to view the hidden image!
