Excellent work! Would be interesting if you made a video about Einstein's 1921 Sidelights lecture where he adds ether back into the equation in special circumstances.
so, the faster you move towards a stationary light emitting object, photons would hit your eye at a faster rate than if you stand still? does this make the objects brighter as you move towards them?
Yes, objects appear brighter the faster you move towards them. It's called the relativistic headlight effect. But it's more complicated then just photons hitting the eye at a faster rate. The angular spread of light rays gets ever more squeezed in a cone around the direction of motion as velocity increases, and gets compounded with time-dilation, plus there is Doppler blue shift.
its a fun thought experiment but its actually wrong. now her is the dilemma. if you have 2 mirrors perpendicuar to each other in perfection so the light keeps bouncing inn a straight line. if its standing still the light bounces between the mirrors (theoreticly as mirrors are not perfect). einsteins mirror clock then moves and the animation shows the light keeps between the mirrors traveling a longer distance. in reality if such a clock was possible. when you move the mirror the light should keep bouncing in the same location while you slide the mirrors sideways untill the light isnt in the center anymore and the mirrors move out of the lightbeam. there is no way a light beam would follow the center of the 2 mirrors. the mirror would just slide out of the way and the beam fies of into infinity. the only way the light moves with the mirrors as they travel is if the mirror would be slightly adjusted to direct the light ahead to where the opposing mirror will be next time its hit
So as a layman let me get this straight. An observer who is in motion at an arbitrary velocity with respect to an observer who is stationary would age more slowly relative to the stationary observer. Would it then be unreasonable to assert that the observer who ages more slowly must be travelling into the future of the other observer? Does this not mean then that the two observers cannot agree on each others " instant " of time " being the " same instant " of time...... or is that clocks just disagree? By this conjecture then are we not forced to deduce that each observer is living in either in the past or future of the other? If this was the case then how could they communicate? I am unaware of any mechanism which would allow me to contact directly, at this instant, with anyone in my past or future, whether it was a year into my past or present or even a nanosecond. I will leave you scientists to show me the error of my ways in the form of a logical explanation should you deem it worthy of a response.
Long story. Let's take it one step at a time. "Would it then be unreasonable to assert that the observer who ages more slowly must be traveling into the future of the other observer?" Well, I would put it a bit differently. Take one moment of the "stationary" observer's time and have him examine clocks co-moving with the moving observer and spread across space. His own clocks, wherever they are, are all synchronized and show the same time. But the moving clocks show different times, depending on their position along the direction of motion: those further back are more advanced then those further ahead. So yes, you can say that at any moment of his time the stationary observer sees across the time of the moving one, from way back in the past to way ahead in the future. Otoh when he follows any of the moving clocks as they travel along, he sees each one of them running slow, all at the same rate, but with different offsets depending on their position relative to the stationary frame. And the same holds for the point of view of the moving observer looking at the stationary one. "Does this not mean then that the two observers cannot agree on each others " instant " of time " being the " same instant " of time...... or is that clocks just disagree?" They do not agree on which events are simultaneous and which are not *when those events happen at distinct locations*. But they do agree on events that happen simultaneously *at the same location*: they always sees such events occurring at the same time and in one place. "By this conjecture then are we not forced to deduce that each observer is living in either in the past or future of the other?" In a way. But each sees the other coming from the past and going to the future, never the other way around. "If this was the case then how could they communicate?" Good question. It all comes down to how time works in conjunction with relativity of simultaneity. Say a recording station in the stationary frame is passed by the moving observer, but at some later time observes an important event at its location and wants to send a warning to the moving observer. The best it can do is send the message at light speed. Now, when the event occurs, the stationary frame observes that the event time on a moving clock over there is in the *future* of the time on a moving clock at the location of the moving observer. But, by the time the light signal catches up to the latter, the event time will already be in the local past of the moving observer. In other words, although running slow, time at the moving observer's location always passes faster than the time needed for the light signal to reach him. So no communication from the future to the past is ever possible in special relativity. "I am unaware of any mechanism which would allow me to contact directly, at this instant, with anyone in my past or future, whether it was a year into my past or present or even a nanosecond." As far as we know right now, there isn't any that works in reality.
Uncertainty Drive . Most grateful for your lengthy reply and explanation. It is refreshing not to be dismissed out of hand as a crank or be the recipient of some form of personal abuse. I will have to read you explanation more than once to take it all in. But if I may, let me put a similar conjecture to you. Using the usual example of the astronaut who travels at near light speed and is away for say ten years as perceived by those left behind on Earth. If the astronaut returns to find everyone on Earth is now ten years older than himself, then surely and by definition he must deduce that has been travelling through" time "with respect to those on Earth, and vice versa for the stationary observers on Earth. If either observer cannot agree on a common " present " whilst one has been in motion relative to the other then surely they couldn't have been in the same timeframe during this relative motion and therefore communication would not have been possible. Since the time dilation equation is valid for all T then any arbitrary velocity of one observer with respect to the other would forbid communication. I am a mathematics hobbyist at the moment although I studied for a year at university. Einstein's equations are really something else. My current understanding of differential geometry is insufficient for me to reach a full comprehension, particularly in respect of derivation and interpretation of the Christoffel symbols, but I'm working on it. Anyway thanks again for your kind reply.
Welcome. I hope things make a bit more sense. "If the astronaut returns to find everyone on Earth is now ten years older than himself, then surely and by definition he must deduce that has been travelling through" time "with respect to those on Earth, and vice versa for the stationary observers on Earth." Again, in a way. In any case, the difference between the times experienced by the two parties has to do not only with time dilation while moving uniformly, but also with that experienced during the acceleration and deceleration legs. Ignoring the latter two is not a good idea, because it leads to contradictions in certain details. You may want to take a look at the explanations in physics.stackexchange.com/questions/242043/what-is-the-proper-way-to-explain-the-twin-paradox. The 3rd answer down explains the pitfalls of the twin paradox "without acceleration". And Einstein's own take on the paradox is another interesting read, see en.wikisource.org/wiki/Translation:Dialog_about_Objections_against_the_Theory_of_Relativity. "If either observer cannot agree on a common " present " whilst one has been in motion relative to the other then surely they couldn't have been in the same timeframe during this relative motion and therefore communication would not have been possible." For *uniform motion* do not imagine the different "timeframes" as distinct separate entities that cannot communicate. They are just different viewpoints across the same space-time and communication is perfectly possible. For *accelerated motion* things are more complicated. The accelerated guy may indeed observe an event horizon beyond which he cannot communicate. In fact he may even outrun a light ray, see 4th answer down in the link I mentioned. As for the Christoffel symbols, they make a lot more sense if you start with curvilinear coordinates in 3D space, where you can really visualize things. see en.wikipedia.org/wiki/Curvilinear_coordinates.
4 года назад
Very nice animation, but has the length contraction already been measured?
Nice vid, however it assumes (as Einstein did) that the light beam inherits the velocity of the mirror of which it is reflected. Instead of moving upwards, it moves slightly sideways travelling a longer distance. Think in reality this would not happen, before the lightbeam is at the height of the second mirror, this mirror is already moved away.
Thanks and sorry for the late reply. No, the calculation doesn’t assume that the light beam inherits velocity from the mirror. It assumes that the beam moves at the same velocity in any direction, whatever the velocity of the mirror on which it reflects. The reason you find the sideways propagation disconcerting is probably because you think of the light beam as a particle beam: if a particle moves sideways after colliding with a surface, it must have acquired a velocity component from that surface. But light is not quite “particles”, even in terms of photons, and in this case it may be helpful to picture it instead in terms of wavefronts. What happens is that wavefronts that are parallel to the mirrors in one frame (say, the moving clock frame) appear tilted when observed from the other (stationary) frame, and conversely. That is, where the clock frame observes wavefronts parallel to its mirrors, the other frame observes tilted wavefronts propagating at an angle relative to the motion of the clock and therefore reflecting off the clock mirrors at an angle. The tilting of the wavefronts is a fundamental phenomenon and unfortunately it’s not emphasized enough. It is the simplest way to understand why the Maxwell equations governing light propagation are invariant under the relativistic Lorentz transformations, but not under the Galilei ones. If you are interested, there is a segment in my video on “Lorentz transformations” that visualizes the tilted wavefronts, although in a different context. It starts around the 2:45 mark.
Thanks for the reply, however, as I do understand what you mean, I think it is still false. You should try to imagine when your clock starts to move from standing still to moving sideways. The light will not follow the mirrors. Not saying that time dilation does not exist, just saying the light clock is a bad example and will not function in the real world, only as thought experiment (think Einstein said the same).
Late reply again. But, try the converse: leave the clock untouched in an inertial frame and imagine yourself accelerating away from it sideways. Clock still functions as it should, throughout your acceleration period until you reach final velocity and settle in a new inertial frame. it is obviously your perception of it that changes.
I understand it, just saying physically a lightclock is not possible, as imagined in yours and other people animations. The light will reflect at the same angle as it hit the surface, and when you start at a 90 degree angle, you can move the mirrors, but it still will reflect at a 90 degree angle, and missing the upper mirror. When the clock is not moving, but it is me that is moving, then indeed it seems that the light is moving at an angle, however, this also means that it will appear that it is travelling a longer way in the same time, so it would be quicker than the speed of the light, but that is only perception. The lightclock is just a bad example, which will leave many people with questions.
"physically a lightclock is not possible": No, it's perfectly possible, nothing physically wrong with the concept. “The light will reflect at the same angle as it hit the surface, and when you start at a 90 degree angle, you can move the mirrors, but it still will reflect at a 90 degree angle, and missing the upper mirror”: This is only true in the clock’s own rest frame. From another moving frame things are different, the reflection laws must take into account the orientation of the reflecting surface relative to the direction of motion. But for a surface parallel to the direction of motion they remain the same as in the rest frame. So you can safely apply them to a clock perpendicular to the direction of motion. “When the clock is not moving, but it is me that is moving, then indeed it seems that the light is moving at an angle, however, this also means that it will appear that it is traveling a longer way in the same time, so it would be quicker than the speed of the light, but that is only perception.”: No, the light beam travels at an angle, and a longer distance than just the length of the clock, but it always travels at the speed of light, that’s the whole crux of the matter. It’s also the thing that rattles our regular intuition. The beam "should" go at a different speed than the speed of light, but it doesn't.
Unfortunately this portrays light as travelling like something akin to a particle (as a vaguely defined "pulse") when in fact light always travels as a probability wave and is absorbed as a quantum/particle. That means that your "pulse" should instead be understood as the intersection of a wave-front (emitted from somewhere along the platform) with a line between top and bottom. A wave-front intersected in this way (with a moving line) will see the point of intersection moving slower than the speed of light (along the line) and not at the speed of light as is being wrongly assumed here. Understood correctly it would be obvious why the "clock" is ticking slower in a moving train. Time dilation is not required. If you adopt this idea please ensure you attribute it to this post.
You said, " in fact light always travels as a probability wave and is absorbed as a quantum/particle." but this is just a very wild guess about how light works. Actually as its based on the idea of Quantum mechanics, its obviously nonsense. But regardless, the illustration of the moving light clock is also totally wrong and BS, and everything about Einstein's theories are just nonsense too.
RUNNING LIGHT CLOCKS SHOW THE ABSOLUTE TIME FOR EACH POINT OF UNIVERSES WHICH I DEFINED BEFORE. For all light clocks ABSOLUTE TIME whether in motion or at rest. Do not worry, the light adjusts its paces velocity for all relative motions the light keep paces with the source’s or observators relative motions Once upon a time, the light was a ping pong ball that was running on the Pythagorean triangle, the wand which was named THE GAMMA born to fuse and to curve the space and the time in minds. Sometimes human beings' reasons lock themselves by using unquestioned complicated prejudices which are so basic in the root.
The relativist mainstream invented the “light clock” to show that, if the speed of light is constant in any reference frame, time dilation can be verified as a real physic effect. However, the imaginary light clock only can fit Einstein’s theory when it moves in a direction perpendicular to the light clock. In this case, the interval of time t (between two tics of the light clock) is measured as a longer interval T when the light clock is moving with respect to the observer, and therefore the interval of time between three tics would be measured as 2T by the same external observer. According to Relativity Theory, T is equal to t multiplied by the so-called gamma factor ... Now, if the light clock moves (with respect to the observer) in the same direction followed by the photon between the clock mirrors (for example, if both are moving in a vertical direction), the intervals measured between the tics of the clock would be very different: longer when both the clock and the photon move down and shorter when the photon moves up and the clock moves down. Therefore, the light clock would show time dilation (between the first tic and the second tic) and time contraction (between the second tic and the third tic). Although t1+t2=2T (the value predicted by Special Relativity), we also have in this case that t1+t2+t1>3T and t2+t1+t2
"the imaginary light clock only can fit Einstein’s theory when it moves in a direction perpendicular to the light clock." Not really. The light clock fits the theory of relativity regardless of its orientation relative to the direction of motion. The reason we use it in only two preferred orientations is to keep things simple and avoid having to explain relativistic shape distortions and modified reflection laws. "if the light clock moves (with respect to the observer) in the same direction followed by the photon between the clock mirrors (for example, if both are moving in a vertical direction), the intervals measured between the tics of the clock would be very different" Correct. As seen by the stationary observer, the intervals displayed by the moving clock are very different. But have you watched this entire video? Because the 3rd part is an extensive segment precisely on a light clock aligned along the direction of motion. It starts at around 5:30. "Therefore, the light clock would show time dilation (between the first tic and the second tic) and time contraction (between the second tic and the third tic)." No. You arrive at this conclusion because you don't account properly for relativity of simultaneity, or better say, how the proper time of the moving frame is observed in the stationary frame. This is usually explained with a bunch of math. But since you are probably annoyed by the intuitive schism, you may want to take a look at my videos on the Length Contraction Paradox, and especially on Lorentz transformations. The latter has a segment on plane lightfronts used to visualize planes of simultaneity, starting at about 2:45. Basically, a plane lightfront that synchronizes clocks along the direction of motion in one frame (and so parallel to that direction) is observed as tilted from the other frame. So the light pulse of a clock aligned along the direction of motion "chases after" its rest frame's planes of simultaneity when going in one direction, and runs against them in the opposite direction. But it always "bounces" between planes of simultaneity corresponding to equal intervals of time in the moving frame. And those intervals of time are always time dilated. "In conclusion, the interval of time measured between an even number of tics cannot be equal to the dilated time predicted by Einstein’s formula, and thus a light clock that moves in the same (vertical) direction which is followed by the photon does not fit the Relativity Theory" See above. Again, the intervals of proper time measured by a light clock are always equal and time dilated. Light clocks are just one way to visualize this, but the essence of time dilation and all that transcends them. It's about the nature of space-time itself. Literally.
The basic formula to calculate relativistic time dilation is the following one: the dilated interval of time (T) is equal to the interval of time (t) multiplied by the gamma factor. T and t are the intervals of time (measured by two different observers) between two tics of the light clock, that is, between two "bounces" of the photon. If the light clock moves in a direction perpendicular to the photon, we have T = t x gamma, 2T = 2t x gamma, 3T = 3t x gamma, 4T = 4t x gamma, 5T = 5t x gamma … The relativistic formula is always correct and (strangely enough) you have not considered the so-called "relativity of simultaneity" for this special case … However, if the light clock moves (with respect to an external observer) in the same direction followed by the photon between the clock mirrors, then we have T ≠ t x gamma, 2T = 2t x gamma, 3T ≠3t x gamma, 4T = 4t x gamma, 5T ≠ 5t x gamma. The relativistic formula fails in this case, seeing that the rate of the clock is variable for the external or "stationary" observer (slow - quick - slow - quick … ), and this means time dilation - time contraction - time dilation - time contraction … In my opinion, the last part of your video simply shows that something goes wrong in this case.It is absurd to argue that relativity of simultaneity solves the problem, because this hypothetic effect should be applied for every case. You cannot apply relativity of simultaneity in the measurement of some intervals (T, 3T, 5T …) and discard it in the measurement of other intervals (2T, 4T, 6T …). And you cannot avoid its application (for every interval of time) when the light clock moves in the direction that fits Special Relativity, that is, when the light clock moves in a direction perpendicular to the photon. This is not a consistent scientific method.
The physicist who created the first cesium atomic-clock, named Louis Essen, was a reputed expert in time measurement and in the measurement of light-speed. He lived until 1997 but he never believed in the relativity of time. He criticized the Special Relativity theory in several articles, and he also criticized the experiments made with atomic clocks in an attempt to prove it (i. e. the Hafele-Keating experiment). See www.ekkehard-friebe.de/Essen-L.htm
I see what you mean. And thank you for Lois Essen's story, I was not aware of it and it is so interesting. But the answer is still negative. "The basic formula to calculate relativistic time dilation is the following one: the dilated interval of time (T) is equal to the interval of time (t) multiplied by the gamma factor." If t is the clock's period in it's own rest frame and T is the period observed in the stationary frame, then yes, correct. With one very important observation: Time dilation only concerns durations t measured at *one single location along the direction of motion* in the clock's frame and the corresponding duration as observed (at two different locations) in another frame. It does NOT apply to durations between events taking place *at different coordinates* along the direction of motion in the clock's frame. And conversely. This is why the vertical clock is so simple: If the clock frame moves in the x direction, all its tics take place at the same coordinate x, albeit at different locations along its length. But if the clock lies along the x-axis, only durations between "round trip" tics at the same end, or any other location, will display time dilation. So, "If the light clock moves in a direction perpendicular to the photon, we have T = t x gamma, 2T = 2t x gamma, 3T = 3t x gamma, 4T = 4t x gamma, 5T = 5t x gamma … " Correct, as explained above. " However, if the light clock moves (with respect to an external observer) in the same direction followed by the photon between the clock mirrors, then we have T ≠ t x gamma, 2T = 2t x gamma, 3T ≠3t x gamma, 4T = 4t x gamma, 5T ≠ 5t x gamma." Partly correct, but the conclusion is wrong. If the sequence of events in the clock frame is (0,0), (ct, t), (0, 2t), (ct, 3t), etc., the corresponding sequence in the other frame is (0,0), ( gamma(1+beta)ct, gamma(1+beta)t ), (2 gamma beta ct, 2 gamma t), ( gamma(1+ 3 beta) ct, gamma (3 + beta) t ), etc. So the stationary frame observes the moving clock to beat time at 0, T, 2 gamma t, T + 2 gamma t, 4 gamma t, etc. In other words, the interval between successive beats *at the same end of the clock* is always 2 gamma t, and this is exactly what time dilation is about. The fact that T is different from (gamma t) does NOT invalidate time dilation, because it is a duration between events taking place at different locations along the x-axis. "In my opinion, the last part of your video simply shows that something goes wrong in this case." No. Nothing goes wrong. Just counter to everyday intuition. "It is absurd to argue that relativity of simultaneity solves the problem, because this hypothetic effect should be applied for every case." I beg to differ on the absurd bit. It always applies in the same way, that's the beauty of it. "You cannot apply relativity of simultaneity in the measurement of some intervals (T, 3T, 5T …) and discard it in the measurement of other intervals (2T, 4T, 6T …). And you cannot avoid its application (for every interval of time) when the light clock moves in the direction that fits Special Relativity, that is, when the light clock moves in a direction perpendicular to the photon." I didn't discard anything at any point. And I certainly did not *apply* relativity of simultaneity to any measurements or events. I simply showed how it *follows* from the speed of light postulate using the clock-along-the-direction-of-motion setup. It just doesn't work the way you assume. Likewise, it wasn't discarded for the vertical clock. It is still there very much, but it simply isn't necessary to invoke it - because 3D geometry still functions the good old way (and is so much easier to understand). As for Lois Essen, we can't deny that strange things happen even to the best of us. I see an intriguing parallel to Einstein himself, who was always at odds with quantum mechanics, although he had a serious hand in its beginnings. Essen never came to terms with relativity, but he gave us the currently accepted value of the speed-of-light, on which all measurements of relativistic effects rely.
Thank you for your long answer, but I still think that you play a "wild card" only when it is convenient for your arguments. This speculative theory is so elastic that it can be accommodated to nearly any fact. For example: You say that the constancy of light-speed in vacuo rely on "all measurements of relativistic effects", but when I discussed the gravitational effect of time dilation (with a theoretical physicist) he told me that, according to General Relativity, the speed of light is only measured as the constant c by a local observer, and not by the distant observers. Therefore, the Second Postulate of Special Relativity was modified by General Relativity, the second part of the same theory, only ten years later ... Maybe you are not aware of other important historical events. The true creator of Special Relativity (and some concepts of General Relativity) was the French Mathematician Jules-Henri Poincaré, basing on the previous studies by Larmor, FitzGerald and Lorentz. In fact, the original contribution of Albert Einstein (to the Special Relativity theory) was very small. See www.brera.unimi.it/sisfa/atti/1998/Giannetto.pdf
Can you explain why the stationary observer and the moving observer will see each others clock pulsing slower? This cannot be factual otherwise how can it be stated that time will slow down for the moving clock. If it was factual this would mean that the stationary observer will age slower as well and at the same rate. If it wasn't true then now you have to deal with the observation. Clearly the diagonal path of the light clock of the stationary ship will be a real observable and measurable event but again, how can that be dealt with rationally if this scenario is equally valid? Could you give your thoughts on the idea that what is actually observed is not a real time event occurrence but rather is a time delayed view, a ghost view of a past event?
On "why the stationary observer and the moving observer will see each others clock pulsing slower": This *is* factual after all, we do have experimental evidence that relatively moving observers do see each other's clocks running slower. The ultimate reason is the speed of light limit, since without it there would be no time dilation, length contraction, or relativity of simultaneity. But the trick to understanding the big picture of it all is to go beyond one single moving clock after we understand that it must run slower. Imagine instead a whole array of equally spaced clocks, all moving at the same velocity relative to you. Not only do they all run slower than your own clock, by the same factor, but they show *different times* (have different offsets) depending on where in the array they are. So what you observe as the state of the moving array at one of your moments in time, is in fact a "space-time cross-section" across the array's own time. That is, different locations in space show us different moments of the array's history. Likewise, an observer traveling with the array sees a "space-time cross-section" of your own frame's history. If you'd like, it is "as if" different observers "look sideways" across space-time, along "different directions". Unfortunately the scale on which we'd have to operate to actually "see" this effect for ourselves is astronomical, and barely in our technological reach right now. We are getting there, but in the meantime we still lack experiential exposure on which to form a working intuition about basic relativistic phenomena. You may want to watch my videos on length contraction, especially the 2nd part of the one on the length contraction paradox, for more details on this point of view.
On "the idea that what is actually observed is not a real time event occurrence but rather is a time delayed view, a ghost view of a past event?" Not quite. Slower rate does not mean "always stuck behind in the past". In fact, for the clock array mentioned before, a snapshot across all of space at one moment of your time captures array clocks showing both past times *and* future times. Yes, you could record the future of the array relative to your time. But being limited to transmitting that info at other points in space at most at light velocity makes the whole thing useless for cheating time: you can never communicate the future to other points in the array ahead of "array time".
To " UncertaintyDrive". I thank you for taking the time to give such an expansive reply to my questions .It is most appreciated. I fully grasp the concepts and explanations that you offer up and I think I can accept the troublesome 'Time' factors in understanding special relativity. I don't think you explained though why both clocks would run slow relative to each other. You seem to be accepting that only one of them is considered as moving.
"why both clocks would run slow relative to each other": Because of the principle of relativity, which is always fundamental. If inertial frame A observes inertial frame B's clock running slowly then it must also hold that frame B observes frame A's clock running just as slowly. Otherwise there would be some preferred inertial frame, and the principle of relativity would not hold. "only one of them is considered as moving": same as above. Whether you mean that one frame is distinguished because it observes a moving clock run slowly, or that one frame is distinguished because it is absolutely moving or, equivalently, absolutely stationary, the answer is the same. The principle of relativity requires that physical laws are the same for all inertial frames and means that there is no such thing as an absolutely stationary frame.
Thanks, I may try to put something together in the future, but don't have anything for the moment unfortunately :) In the meantime you may be interested in Cassiopeia Project videos on Quantum Mechanics, www.cassiopeiaproject.com/vid_courses3.php?Tape_Name=QM. Ch.6 deals with wave function collapse, entanglement, etc.
TIME-DILATION IS A FALLACY! At 2:12 the path of the light-beam is NOT a diagonal - it's actually identical to the stationary clock (UP and DOWN only). Your triangle/zig-zag illustration (as used by many) is incorrect and misleading because it shows the TRUE, VERTICAL position of the light beam plotted HORIZONTALLY, giving the impression that it's ANGLED, and hence, longer. In reality, there is NO difference in the distance the light-beam has to travel, or in the amount of elapsed time for BOTH clocks. Time dilation? What time dilation…?
Gents, a common misconception is that the proper lenght/trajectory is diagonal! That's false and relativity has nothing to do with this. Diagonal is the trajectory as seen by one other observer, the viceversa holds true either; the "statuionary" observer, stationary with respect to its frame, sees the beam UP and DOWN, so BOTH see light travel UP and DOWN. The same concept applies to length contraction. You CANNOT compare time pace and space extension as seen in differing frames and states that they are different. To do that, you have to "transport" quantities from one frame to the other. Actual the length of the light clock is the same, this is the proper length, a concept that relates to proper time. Bottom line is that both perceives the clock of the moving frame as ticking at a lower pace. But at the end of the day only the moving clock slows down! Moving with respect to what? what is the "absolute" reference to say a clock is moving faster than one other? It's the light cone, the array of the light cones as they materialized throughout the while space-time. I striogly recommeng this reading: “Close to the Speed of Light”: Dispersing Various Twin Paradox Related Confusions" by M. Arsenijevic, where the meaning of the misleading word "relativity" is physically addressed: the word relativity is actually a pitfall and nowadays used and abused like it was for the word incompleteness of the incompleteness theorem of the mathematics. Contrary to popular belief an absolute entity still exists even in relativity ... read and discover the clue to any apparent paradox.
UncertaintyDrive Mostly the off monotone and pronunciation. The video really did help me understand relativity. I have a couple of questions though. What happens when two objects pass each other faster than half the speed of light (say, 60% c). Relative to each other they should go 120% c but we both know that's impossible. What keeps that from happening? My second question is similar but for this one the two objects move away from each other at 60% c from a central point. Relative to each other the opposing object should be moving away at 120% c but that is impossible. Why and what would an observer on either of the objects see in this scenario?
THUNDERTURTLE Your two questions are actually a single one, since the objects go toward each other before they meet, and away from each other after that, all the while having the same velocities relative to the observing frame. In any case, in the frame that observes both objects going at ±0.6c, their apparent separation does decrease/increase at a rate of 1.2c. Just as you'd expect, the lower/upper limit for the rate of change of their separation is ±2c. But this rate is not a proper relative velocity. That is, it is not the velocity at which one object observes the other, neither is it a velocity relative to the observing frame. The true relative velocity of the two objects is given by the relativistic velocity addition formula, which unlike the Galilean one is nonlinear, and always gives a result less than c. The correct relative velocity of the 2 objects is (0.6c + 0.6c)/[1+(0.6c x 0.6c)/c^2] ~ 0.88c. The reason for this counterintuitive composition rule is ultimately relativity of simultaneity, because what one frame observes as simultaneous positions, appear as non-simultaneous positions in another frame. Since each frame defines distances and velocities by means of simultaneous positions, this means that different frames must use completely different events to evaluate relative velocities and the simple Galilean rule no longer applies.
So Einstein was wrong, there’s nothing distinct between either clock. Why would a person in movement age slower than his stationary twin if both brothers perceive the other moving?
silverrahul wait, how long ago was 3 week? I already figured out this problem. The reason is because for one twin to move in the first place, he had to accelerate which causes time dilation cuz of special relativity and stuff. Doesn’t an object in motion feel more drag than a stationary object. I imagine if there was a quantum mechanical explanation, it would have something to do with drag and slowing the motions of all particles in a person’s body, forcing them to physically age slower as their DNA would have trouble replicating, causing DNA replication and therefore aging of the person to slow down.
silverrahul No, I mean theoretically it could work like that. I mean technically speaking, we haven’t actually proven that a dimension of time even exists nor have we proven that time exists. Hell, it could just be an emergent property of our universe.
disagree. the closer you get to C, the light bends perpendicular to the motion. Light movement is unrelated to the movement of the source or target. faster than -.87 C, the light would bend such that it would not even reach the target. I can't believe these so-called explanations of relativity using a light clock. BTW no one has ever built an actual light clock.
If you can type in English then you can speak in English. I'm sorry but being able to speak to an audience / explain concepts to people is pretty basic and essential in life.
As an animator, I can see that the animation. Is cheated to make the example This cheat makes me doubt this explanation The cheat - if light bounce keyframes are every 30frames, it will bounce every 30 frames even if the mirror is moving
You haven't understood it. That is the whole point. Because the light must travel further and always does so at a constant speed it will bounce less often, in other words time ticks slower.
Excellent explanation. Very easy to understand. Thank you. It's a shame about some of the comments :-(
Great visuals, ver clear, thank you!
Brilliant video, cleared up some things I have been pondering for years.
Excellent work! Would be interesting if you made a video about Einstein's 1921 Sidelights lecture where he adds ether back into the equation in special circumstances.
so, the faster you move towards a stationary light emitting object, photons would hit your eye at a faster rate than if you stand still? does this make the objects brighter as you move towards them?
Yes, objects appear brighter the faster you move towards them. It's called the relativistic headlight effect. But it's more complicated then just photons hitting the eye at a faster rate. The angular spread of light rays gets ever more squeezed in a cone around the direction of motion as velocity increases, and gets compounded with time-dilation, plus there is Doppler blue shift.
its a fun thought experiment but its actually wrong.
now her is the dilemma. if you have 2 mirrors perpendicuar to each other in perfection so the light keeps bouncing inn a straight line.
if its standing still the light bounces between the mirrors (theoreticly as mirrors are not perfect).
einsteins mirror clock then moves and the animation shows the light keeps between the mirrors traveling a longer distance.
in reality if such a clock was possible. when you move the mirror the light should keep bouncing in the same location while you slide the mirrors sideways untill the light isnt in the center anymore and the mirrors move out of the lightbeam.
there is no way a light beam would follow the center of the 2 mirrors. the mirror would just slide out of the way and the beam fies of into infinity.
the only way the light moves with the mirrors as they travel is if the mirror would be slightly adjusted to direct the light ahead to where the opposing mirror will be next time its hit
So as a layman let me get this straight. An observer who is in motion at an arbitrary velocity with respect to an observer who is stationary would age more slowly relative to the stationary observer. Would it then be unreasonable to assert that the observer who ages more slowly must be travelling into the future of the other observer? Does this not mean then that the two observers cannot agree on each others " instant " of time " being the " same instant " of time...... or is that clocks just disagree? By this conjecture then are we not forced to deduce that each observer is living in either in the past or future of the other? If this was the case then how could they communicate? I am unaware of any mechanism which would allow me to contact directly, at this instant, with anyone in my past or future, whether it was a year into my past or present or even a nanosecond. I will leave you scientists to show me the error of my ways in the form of a logical explanation should you deem it worthy of a response.
Long story. Let's take it one step at a time.
"Would it then be unreasonable to assert that the observer who ages more slowly must be traveling into the future of the other observer?" Well, I would put it a bit differently. Take one moment of the "stationary" observer's time and have him examine clocks co-moving with the moving observer and spread across space. His own clocks, wherever they are, are all synchronized and show the same time. But the moving clocks show different times, depending on their position along the direction of motion: those further back are more advanced then those further ahead. So yes, you can say that at any moment of his time the stationary observer sees across the time of the moving one, from way back in the past to way ahead in the future. Otoh when he follows any of the moving clocks as they travel along, he sees each one of them running slow, all at the same rate, but with different offsets depending on their position relative to the stationary frame. And the same holds for the point of view of the moving observer looking at the stationary one.
"Does this not mean then that the two observers cannot agree on each others " instant " of time " being the " same instant " of time...... or is that clocks just disagree?" They do not agree on which events are simultaneous and which are not *when those events happen at distinct locations*. But they do agree on events that happen simultaneously *at the same location*: they always sees such events occurring at the same time and in one place.
"By this conjecture then are we not forced to deduce that each observer is living in either in the past or future of the other?" In a way. But each sees the other coming from the past and going to the future, never the other way around.
"If this was the case then how could they communicate?" Good question. It all comes down to how time works in conjunction with relativity of simultaneity. Say a recording station in the stationary frame is passed by the moving observer, but at some later time observes an important event at its location and wants to send a warning to the moving observer. The best it can do is send the message at light speed. Now, when the event occurs, the stationary frame observes that the event time on a moving clock over there is in the *future* of the time on a moving clock at the location of the moving observer. But, by the time the light signal catches up to the latter, the event time will already be in the local past of the moving observer. In other words, although running slow, time at the moving observer's location always passes faster than the time needed for the light signal to reach him. So no communication from the future to the past is ever possible in special relativity.
"I am unaware of any mechanism which would allow me to contact directly, at this instant, with anyone in my past or future, whether it was a year into my past or present or even a nanosecond." As far as we know right now, there isn't any that works in reality.
Uncertainty Drive . Most grateful for your lengthy reply and explanation. It is refreshing not to be dismissed out of hand as a crank or be the recipient of some form of personal abuse. I will have to read you explanation more than once to take it all in. But if I may, let me put a similar conjecture to you. Using the usual example of the astronaut who travels at near light speed and is away for say ten years as perceived by those left behind on Earth. If the astronaut returns to find everyone on Earth is now ten years older than himself, then surely and by definition he must deduce that has been travelling through" time "with respect to those on Earth, and vice versa for the stationary observers on Earth. If either observer cannot agree on a common " present " whilst one has been in motion relative to the other then surely they couldn't have been in the same timeframe during this relative motion and therefore communication would not have been possible. Since the time dilation equation is valid for all T then any arbitrary velocity of one observer with respect to the other would forbid communication. I am a mathematics hobbyist at the moment although I studied for a year at university. Einstein's equations are really something else. My current understanding of differential geometry is insufficient for me to reach a full comprehension, particularly in respect of derivation and interpretation of the Christoffel symbols, but I'm working on it. Anyway thanks again for your kind reply.
Welcome. I hope things make a bit more sense.
"If the astronaut returns to find everyone on Earth is now ten years older than himself, then surely and by definition he must deduce that has been travelling through" time "with respect to those on Earth, and vice versa for the stationary observers on Earth."
Again, in a way. In any case, the difference between the times experienced by the two parties has to do not only with time dilation while moving uniformly, but also with that experienced during the acceleration and deceleration legs. Ignoring the latter two is not a good idea, because it leads to contradictions in certain details. You may want to take a look at the explanations in physics.stackexchange.com/questions/242043/what-is-the-proper-way-to-explain-the-twin-paradox. The 3rd answer down explains the pitfalls of the twin paradox "without acceleration". And Einstein's own take on the paradox is another interesting read, see en.wikisource.org/wiki/Translation:Dialog_about_Objections_against_the_Theory_of_Relativity.
"If either observer cannot agree on a common " present " whilst one has been in motion relative to the other then surely they couldn't have been in the same timeframe during this relative motion and therefore communication would not have been possible."
For *uniform motion* do not imagine the different "timeframes" as distinct separate entities that cannot communicate. They are just different viewpoints across the same space-time and communication is perfectly possible. For *accelerated motion* things are more complicated. The accelerated guy may indeed observe an event horizon beyond which he cannot communicate. In fact he may even outrun a light ray, see 4th answer down in the link I mentioned.
As for the Christoffel symbols, they make a lot more sense if you start with curvilinear coordinates in 3D space, where you can really visualize things. see en.wikipedia.org/wiki/Curvilinear_coordinates.
Very nice animation, but has the length contraction already been measured?
Nice vid, however it assumes (as Einstein did) that the light beam inherits the velocity of the mirror of which it is reflected. Instead of moving upwards, it moves slightly sideways travelling a longer distance. Think in reality this would not happen, before the lightbeam is at the height of the second mirror, this mirror is already moved away.
Thanks and sorry for the late reply.
No, the calculation doesn’t assume that the light beam inherits velocity from the mirror. It assumes that the beam moves at the same velocity in any direction, whatever the velocity of the mirror on which it reflects. The reason you find the sideways propagation disconcerting is probably because you think of the light beam as a particle beam: if a particle moves sideways after colliding with a surface, it must have acquired a velocity component from that surface. But light is not quite “particles”, even in terms of photons, and in this case it may be helpful to picture it instead in terms of wavefronts.
What happens is that wavefronts that are parallel to the mirrors in one frame (say, the moving clock frame) appear tilted when observed from the other (stationary) frame, and conversely. That is, where the clock frame observes wavefronts parallel to its mirrors, the other frame observes tilted wavefronts propagating at an angle relative to the motion of the clock and therefore reflecting off the clock mirrors at an angle.
The tilting of the wavefronts is a fundamental phenomenon and unfortunately it’s not emphasized enough. It is the simplest way to understand why the Maxwell equations governing light propagation are invariant under the relativistic Lorentz transformations, but not under the Galilei ones.
If you are interested, there is a segment in my video on “Lorentz transformations” that visualizes the tilted wavefronts, although in a different context. It starts around the 2:45 mark.
Thanks for the reply, however, as I do understand what you mean, I think it is still false. You should try to imagine when your clock starts to move from standing still to moving sideways. The light will not follow the mirrors. Not saying that time dilation does not exist, just saying the light clock is a bad example and will not function in the real world, only as thought experiment (think Einstein said the same).
Late reply again. But, try the converse: leave the clock untouched in an inertial frame and imagine yourself accelerating away from it sideways. Clock still functions as it should, throughout your acceleration period until you reach final velocity and settle in a new inertial frame. it is obviously your perception of it that changes.
I understand it, just saying physically a lightclock is not possible, as imagined in yours and other people animations. The light will reflect at the same angle as it hit the surface, and when you start at a 90 degree angle, you can move the mirrors, but it still will reflect at a 90 degree angle, and missing the upper mirror. When the clock is not moving, but it is me that is moving, then indeed it seems that the light is moving at an angle, however, this also means that it will appear that it is travelling a longer way in the same time, so it would be quicker than the speed of the light, but that is only perception. The lightclock is just a bad example, which will leave many people with questions.
"physically a lightclock is not possible": No, it's perfectly possible, nothing physically wrong with the concept.
“The light will reflect at the same angle as it hit the surface, and when you start at a 90 degree angle, you can move the mirrors, but it still will reflect at a 90 degree angle, and missing the upper mirror”: This is only true in the clock’s own rest frame. From another moving frame things are different, the reflection laws must take into account the orientation of the reflecting surface relative to the direction of motion. But for a surface parallel to the direction of motion they remain the same as in the rest frame. So you can safely apply them to a clock perpendicular to the direction of motion.
“When the clock is not moving, but it is me that is moving, then indeed it seems that the light is moving at an angle, however, this also means that it will appear that it is traveling a longer way in the same time, so it would be quicker than the speed of the light, but that is only perception.”: No, the light beam travels at an angle, and a longer distance than just the length of the clock, but it always travels at the speed of light, that’s the whole crux of the matter. It’s also the thing that rattles our regular intuition. The beam "should" go at a different speed than the speed of light, but it doesn't.
Unfortunately this portrays light as travelling like something akin to a particle (as a vaguely defined "pulse") when in fact light always travels as a probability wave and is absorbed as a quantum/particle. That means that your "pulse" should instead be understood as the intersection of a wave-front (emitted from somewhere along the platform) with a line between top and bottom. A wave-front intersected in this way (with a moving line) will see the point of intersection moving slower than the speed of light (along the line) and not at the speed of light as is being wrongly assumed here. Understood correctly it would be obvious why the "clock" is ticking slower in a moving train. Time dilation is not required. If you adopt this idea please ensure you attribute it to this post.
You said, " in fact light always travels as a probability wave and is absorbed as a quantum/particle." but this is just a very wild guess about how light works. Actually as its based on the idea of Quantum mechanics, its obviously nonsense. But regardless, the illustration of the moving light clock is also totally wrong and BS, and everything about Einstein's theories are just nonsense too.
very well done
Indeed nice video. What software was used to create this nice animation>?
Thanks. All animations were made with Blender.
RUNNING LIGHT CLOCKS SHOW THE ABSOLUTE TIME FOR EACH POINT OF UNIVERSES WHICH I DEFINED BEFORE. For all light clocks ABSOLUTE TIME whether in motion or at rest. Do not worry, the light adjusts its paces velocity for all relative motions the light keep paces with the source’s or observators relative motions
Once upon a time, the light was a ping pong ball that was running on the Pythagorean triangle, the wand which was named THE GAMMA born to fuse and to curve the space and the time in minds. Sometimes human beings' reasons lock themselves by using unquestioned complicated prejudices which are so basic in the root.
The relativist mainstream invented the “light clock” to show that, if the speed of light is constant in any reference frame, time dilation can be verified as a real physic effect. However, the imaginary light clock only can fit Einstein’s theory when it moves in a direction perpendicular to the light clock. In this case, the interval of time t (between two tics of the light clock) is measured as a longer interval T when the light clock is moving with respect to the observer, and therefore the interval of time between three tics would be measured as 2T by the same external observer. According to Relativity Theory, T is equal to t multiplied by the so-called gamma factor ...
Now, if the light clock moves (with respect to the observer) in the same direction followed by the photon between the clock mirrors (for example, if both are moving in a vertical direction), the intervals measured between the tics of the clock would be very different: longer when both the clock and the photon move down and shorter when the photon moves up and the clock moves down. Therefore, the light clock would show time dilation (between the first tic and the second tic) and time contraction (between the second tic and the third tic). Although t1+t2=2T (the value predicted by Special Relativity), we also have in this case that t1+t2+t1>3T and t2+t1+t2
"the imaginary light clock only can fit Einstein’s theory when it moves in a direction perpendicular to the light clock." Not really. The light clock fits the theory of relativity regardless of its orientation relative to the direction of motion. The reason we use it in only two preferred orientations is to keep things simple and avoid having to explain relativistic shape distortions and modified reflection laws.
"if the light clock moves (with respect to the observer) in the same direction followed by the photon between the clock mirrors (for example, if both are moving in a vertical direction), the intervals measured between the tics of the clock would be very different" Correct. As seen by the stationary observer, the intervals displayed by the moving clock are very different. But have you watched this entire video? Because the 3rd part is an extensive segment precisely on a light clock aligned along the direction of motion. It starts at around 5:30.
"Therefore, the light clock would show time dilation (between the first tic and the second tic) and time contraction (between the second tic and the third tic)." No. You arrive at this conclusion because you don't account properly for relativity of simultaneity, or better say, how the proper time of the moving frame is observed in the stationary frame. This is usually explained with a bunch of math. But since you are probably annoyed by the intuitive schism, you may want to take a look at my videos on the Length Contraction Paradox, and especially on Lorentz transformations. The latter has a segment on plane lightfronts used to visualize planes of simultaneity, starting at about 2:45. Basically, a plane lightfront that synchronizes clocks along the direction of motion in one frame (and so parallel to that direction) is observed as tilted from the other frame. So the light pulse of a clock aligned along the direction of motion "chases after" its rest frame's planes of simultaneity when going in one direction, and runs against them in the opposite direction. But it always "bounces" between planes of simultaneity corresponding to equal intervals of time in the moving frame. And those intervals of time are always time dilated.
"In conclusion, the interval of time measured between an even number of tics cannot be equal to the dilated time predicted by Einstein’s formula, and thus a light clock that moves in the same (vertical) direction which is followed by the photon does not fit the Relativity Theory" See above. Again, the intervals of proper time measured by a light clock are always equal and time dilated. Light clocks are just one way to visualize this, but the essence of time dilation and all that transcends them. It's about the nature of space-time itself. Literally.
The basic formula to calculate relativistic time dilation is the following one: the dilated interval of time (T) is equal to the interval of time (t) multiplied by the gamma factor. T and t are the intervals of time (measured by two different observers) between two tics of the light clock, that is, between two "bounces" of the photon. If the light clock moves in a direction perpendicular to the photon, we have T = t x gamma, 2T = 2t x gamma, 3T = 3t x gamma, 4T = 4t x gamma, 5T = 5t x gamma … The relativistic formula is always correct and (strangely enough) you have not considered the so-called "relativity of simultaneity" for this special case … However, if the light clock moves (with respect to an external observer) in the same direction followed by the photon between the clock mirrors, then we have T ≠ t x gamma, 2T = 2t x gamma, 3T ≠3t x gamma, 4T = 4t x gamma, 5T ≠ 5t x gamma. The relativistic formula fails in this case, seeing that the rate of the clock is variable for the external or "stationary" observer (slow - quick - slow - quick … ), and this means time dilation - time contraction - time dilation - time contraction … In my opinion, the last part of your video simply shows that something goes wrong in this case.It is absurd to argue that relativity of simultaneity solves the problem, because this hypothetic effect should be applied for every case. You cannot apply relativity of simultaneity in the measurement of some intervals (T, 3T, 5T …) and discard it in the measurement of other intervals (2T, 4T, 6T …). And you cannot avoid its application (for every interval of time) when the light
clock moves in the direction that fits Special Relativity, that is, when the light clock moves in a direction perpendicular to the photon. This is not a consistent scientific method.
The physicist who created the first cesium atomic-clock, named Louis Essen, was a reputed expert in time measurement and in the measurement of light-speed. He lived until 1997 but he never believed in the relativity of time. He criticized the Special Relativity theory in several articles, and he also criticized the experiments made with atomic clocks in an attempt to prove it (i. e. the Hafele-Keating experiment). See www.ekkehard-friebe.de/Essen-L.htm
I see what you mean. And thank you for Lois Essen's story, I was not aware of it and it is so interesting. But the answer is still negative.
"The basic formula to calculate relativistic time dilation is the following one: the dilated interval of time (T) is equal to the interval of time (t) multiplied by the gamma factor." If t is the clock's period in it's own rest frame and T is the period observed in the stationary frame, then yes, correct. With one very important observation: Time dilation only concerns durations t measured at *one single location along the direction of motion* in the clock's frame and the corresponding duration as observed (at two different locations) in another frame. It does NOT apply to durations between events taking place *at different coordinates* along the direction of motion in the clock's frame. And conversely.
This is why the vertical clock is so simple: If the clock frame moves in the x direction, all its tics take place at the same coordinate x, albeit at different locations along its length. But if the clock lies along the x-axis, only durations between "round trip" tics at the same end, or any other location, will display time dilation. So,
"If the light clock moves in a direction perpendicular to the photon, we have T = t x gamma, 2T = 2t x gamma, 3T = 3t x gamma, 4T = 4t x gamma, 5T = 5t x gamma … " Correct, as explained above.
" However, if the light clock moves (with respect to an external observer) in the same direction followed by the photon between the clock mirrors, then we have T ≠ t x gamma, 2T = 2t x gamma, 3T ≠3t x gamma, 4T = 4t x gamma, 5T ≠ 5t x gamma." Partly correct, but the conclusion is wrong. If the sequence of events in the clock frame is (0,0), (ct, t), (0, 2t), (ct, 3t), etc., the corresponding sequence in the other frame is (0,0), ( gamma(1+beta)ct, gamma(1+beta)t ), (2 gamma beta ct, 2 gamma t), ( gamma(1+ 3 beta) ct, gamma (3 + beta) t ), etc. So the stationary frame observes the moving clock to beat time at 0, T, 2 gamma t, T + 2 gamma t, 4 gamma t, etc. In other words, the interval between successive beats *at the same end of the clock* is always 2 gamma t, and this is exactly what time dilation is about. The fact that T is different from (gamma t) does NOT invalidate time dilation, because it is a duration between events taking place at different locations along the x-axis.
"In my opinion, the last part of your video simply shows that something goes wrong in this case." No. Nothing goes wrong. Just counter to everyday intuition.
"It is absurd to argue that relativity of simultaneity solves the problem, because this hypothetic effect should be applied for every case." I beg to differ on the absurd bit. It always applies in the same way, that's the beauty of it.
"You cannot apply relativity of simultaneity in the measurement of some intervals (T, 3T, 5T …) and discard it in the measurement of other intervals (2T, 4T, 6T …). And you cannot avoid its application (for every interval of time) when the light clock moves in the direction that fits Special Relativity, that is, when the light clock moves in a direction perpendicular to the photon." I didn't discard anything at any point. And I certainly did not *apply* relativity of simultaneity to any measurements or events. I simply showed how it *follows* from the speed of light postulate using the clock-along-the-direction-of-motion setup. It just doesn't work the way you assume. Likewise, it wasn't discarded for the vertical clock. It is still there very much, but it simply isn't necessary to invoke it - because 3D geometry still functions the good old way (and is so much easier to understand).
As for Lois Essen, we can't deny that strange things happen even to the best of us. I see an intriguing parallel to Einstein himself, who was always at odds with quantum mechanics, although he had a serious hand in its beginnings. Essen never came to terms with relativity, but he gave us the currently accepted value of the speed-of-light, on which all measurements of relativistic effects rely.
Thank you for your long answer, but I still think that you play a "wild card" only when it is convenient for your arguments. This speculative theory is so elastic that it can be accommodated to nearly any fact. For example: You say that the constancy of light-speed in vacuo rely on "all measurements of relativistic effects", but when I discussed the gravitational effect of time dilation (with a theoretical physicist) he told me that, according to General Relativity, the speed of light is only measured as the constant c by a local observer, and not by the distant observers. Therefore, the Second Postulate of Special Relativity was modified by General Relativity, the second part of the same theory, only ten years later ... Maybe you are not aware of other important historical events. The true creator of Special Relativity (and some concepts of General Relativity) was the French Mathematician Jules-Henri Poincaré, basing on the previous studies by Larmor, FitzGerald and Lorentz. In fact, the original contribution of Albert Einstein (to the Special Relativity theory) was very small. See www.brera.unimi.it/sisfa/atti/1998/Giannetto.pdf
Can you explain why the stationary observer and the moving observer will see each others clock pulsing slower? This cannot be factual otherwise how can it be stated that time will slow down for the moving clock. If it was factual this would mean that the stationary observer will age slower as well and at the same rate. If it wasn't true then now you have to deal with the observation. Clearly the diagonal path of the light clock of the stationary ship will be a real observable and measurable event but again, how can that be dealt with rationally if this scenario is equally valid?
Could you give your thoughts on the idea that what is actually observed is not a real time event occurrence but rather is a time delayed view, a ghost view of a past event?
On "why the stationary observer and the moving observer will see each others clock pulsing slower": This *is* factual after all, we do have experimental evidence that relatively moving observers do see each other's clocks running slower. The ultimate reason is the speed of light limit, since without it there would be no time dilation, length contraction, or relativity of simultaneity. But the trick to understanding the big picture of it all is to go beyond one single moving clock after we understand that it must run slower. Imagine instead a whole array of equally spaced clocks, all moving at the same velocity relative to you. Not only do they all run slower than your own clock, by the same factor, but they show *different times* (have different offsets) depending on where in the array they are. So what you observe as the state of the moving array at one of your moments in time, is in fact a "space-time cross-section" across the array's own time. That is, different locations in space show us different moments of the array's history. Likewise, an observer traveling with the array sees a "space-time cross-section" of your own frame's history. If you'd like, it is "as if" different observers "look sideways" across space-time, along "different directions". Unfortunately the scale on which we'd have to operate to actually "see" this effect for ourselves is astronomical, and barely in our technological reach right now. We are getting there, but in the meantime we still lack experiential exposure on which to form a working intuition about basic relativistic phenomena. You may want to watch my videos on length contraction, especially the 2nd part of the one on the length contraction paradox, for more details on this point of view.
On "the idea that what is actually observed is not a real time event occurrence but rather is a time delayed view, a ghost view of a past event?" Not quite. Slower rate does not mean "always stuck behind in the past". In fact, for the clock array mentioned before, a snapshot across all of space at one moment of your time captures array clocks showing both past times *and* future times. Yes, you could record the future of the array relative to your time. But being limited to transmitting that info at other points in space at most at light velocity makes the whole thing useless for cheating time: you can never communicate the future to other points in the array ahead of "array time".
To " UncertaintyDrive".
I thank you for taking the time to give such an expansive reply to my questions .It is most appreciated. I fully grasp the concepts and explanations that you offer up and I think I can accept the troublesome 'Time' factors in understanding special relativity. I don't think you explained though why both clocks would run slow relative to each other. You seem to be accepting that only one of them is considered as moving.
"why both clocks would run slow relative to each other": Because of the principle of relativity, which is always fundamental. If inertial frame A observes inertial frame B's clock running slowly then it must also hold that frame B observes frame A's clock running just as slowly. Otherwise there would be some preferred inertial frame, and the principle of relativity would not hold.
"only one of them is considered as moving": same as above. Whether you mean that one frame is distinguished because it observes a moving clock run slowly, or that one frame is distinguished because it is absolutely moving or, equivalently, absolutely stationary, the answer is the same. The principle of relativity requires that physical laws are the same for all inertial frames and means that there is no such thing as an absolutely stationary frame.
If you search for explanations of the ''Twins Paradox' it will help to understand how this is possible.
Use a bloody normal voice and some better or no bg music next time
Can't you sound like a sane person not like a kidnapper calling for ransom
Can you explain the Wave function collapse in the same way? And explain why and how it happens? en.wikipedia.org/wiki/Wave_function_collapse
Thanks, I may try to put something together in the future, but don't have anything for the moment unfortunately :) In the meantime you may be interested in Cassiopeia Project videos on Quantum Mechanics, www.cassiopeiaproject.com/vid_courses3.php?Tape_Name=QM. Ch.6 deals with wave function collapse, entanglement, etc.
TIME-DILATION IS A FALLACY! At 2:12 the path of the light-beam is NOT a diagonal - it's actually identical to the stationary clock (UP and DOWN only). Your triangle/zig-zag illustration (as used by many) is incorrect and misleading because it shows the TRUE, VERTICAL position of the light beam plotted HORIZONTALLY, giving the impression that it's ANGLED, and hence, longer. In reality, there is NO difference in the distance the light-beam has to travel, or in the amount of elapsed time for BOTH clocks. Time dilation? What time dilation…?
If the vertical position is plotted horizontally then what's plotted vertically?
Also, isnt the speed of light, the speed of light, no matter what? Even if travelling in a light clock moving at the speed of light?
GPS satellites have faster running clocks because orbiting the earth makes their clocks run slower
@@adawg3032 Is that to keep them in sync with Real Time or, with global time-zones?
Gents, a common misconception is that the proper lenght/trajectory is diagonal! That's false and relativity has nothing to do with this. Diagonal is the trajectory as seen by one other observer, the viceversa holds true either; the "statuionary" observer, stationary with respect to its frame, sees the beam UP and DOWN, so BOTH see light travel UP and DOWN. The same concept applies to length contraction. You CANNOT compare time pace and space extension as seen in differing frames and states that they are different. To do that, you have to "transport" quantities from one frame to the other. Actual the length of the light clock is the same, this is the proper length, a concept that relates to proper time. Bottom line is that both perceives the clock of the moving frame as ticking at a lower pace. But at the end of the day only the moving clock slows down! Moving with respect to what? what is the "absolute" reference to say a clock is moving faster than one other? It's the light cone, the array of the light cones as they materialized throughout the while space-time. I striogly recommeng this reading: “Close to the Speed of Light”: Dispersing Various Twin Paradox Related Confusions" by M. Arsenijevic, where the meaning of the misleading word "relativity" is physically addressed: the word relativity is actually a pitfall and nowadays used and abused like it was for the word incompleteness of the incompleteness theorem of the mathematics. Contrary to popular belief an absolute entity still exists even in relativity ... read and discover the clue to any apparent paradox.
Cool video, but robo voice was very annoying.
Thanks. Sorry about the voice, but it's much better than mine, believe me. Is it the pitch, the tempo, the intonation?
UncertaintyDrive Mostly the off monotone and pronunciation. The video really did help me understand relativity.
I have a couple of questions though. What happens when two objects pass each other faster than half the speed of light (say, 60% c). Relative to each other they should go 120% c but we both know that's impossible. What keeps that from happening? My second question is similar but for this one the two objects move away from each other at 60% c from a central point. Relative to each other the opposing object should be moving away at 120% c but that is impossible. Why and what would an observer on either of the objects see in this scenario?
THUNDERTURTLE Your two questions are actually a single one, since the objects go toward each other before they meet, and away from each other after that, all the while having the same velocities relative to the observing frame.
In any case, in the frame that observes both objects going at ±0.6c, their apparent separation does decrease/increase at a rate of 1.2c. Just as you'd expect, the lower/upper limit for the rate of change of their separation is ±2c. But this rate is not a proper relative velocity. That is, it is not the velocity at which one object observes the other, neither is it a velocity relative to the observing frame. The true relative velocity of the two objects is given by the relativistic velocity addition formula, which unlike the Galilean one is nonlinear, and always gives a result less than c. The correct relative velocity of the 2 objects is (0.6c + 0.6c)/[1+(0.6c x 0.6c)/c^2] ~ 0.88c. The reason for this counterintuitive composition rule is ultimately relativity of simultaneity, because what one frame observes as simultaneous positions, appear as non-simultaneous positions in another frame. Since each frame defines distances and velocities by means of simultaneous positions, this means that different frames must use completely different events to evaluate relative velocities and the simple Galilean rule no longer applies.
I couldn't watch the entire video. The music is WAY too loud and and annoying.
So Einstein was wrong, there’s nothing distinct between either clock. Why would a person in movement age slower than his stationary twin if both brothers perceive the other moving?
silverrahul wait, how long ago was 3 week? I already figured out this problem. The reason is because for one twin to move in the first place, he had to accelerate which causes time dilation cuz of special relativity and stuff. Doesn’t an object in motion feel more drag than a stationary object. I imagine if there was a quantum mechanical explanation, it would have something to do with drag and slowing the motions of all particles in a person’s body, forcing them to physically age slower as their DNA would have trouble replicating, causing DNA replication and therefore aging of the person to slow down.
silverrahul No, I mean theoretically it could work like that. I mean technically speaking, we haven’t actually proven that a dimension of time even exists nor have we proven that time exists. Hell, it could just be an emergent property of our universe.
This narrator's voice is creepy as heck.
Oh, come on...
no good
disagree. the closer you get to C, the light bends perpendicular to the motion. Light movement is unrelated to the movement of the source or target. faster than -.87 C, the light would bend such that it would not even reach the target. I can't believe these so-called explanations of relativity using a light clock. BTW no one has ever built an actual light clock.
If you can type in English then you can speak in English. I'm sorry but being able to speak to an audience / explain concepts to people is pretty basic and essential in life.
As an animator, I can see that the animation. Is cheated to make the example
This cheat makes me doubt this explanation
The cheat - if light bounce keyframes are every 30frames, it will bounce every 30 frames even if the mirror is moving
As a non animator, I can see that too
You haven't understood it. That is the whole point. Because the light must travel further and always does so at a constant speed it will bounce less often, in other words time ticks slower.