From 15 years of RUclips, I still have this guy at the top of the true quality list. Many people don't like the halting problem one because they don't understand the implications of the simply proof. It's actually one of my favorite, though. I am glad he redid this one, for sure, because the 15 year old version of this video was one of my favorite videos, for usefulness, of all time.
This was a topic that took me longer than I'd like to admit to understand the first time I was learning it, and this video makes spacetime diagrams so easy to comprehend. 10/10
One thing i would recommend to videos like this with slow stable panning animations is to render it at 120fps and encode the video as 60fps to avoid jitter and trembling. It's hard to watch certain parts of it at low framerate. Since this is all simple 3D renders i don't think i changes anything about the workflow other than having to wait a bit longer for the video to export.
I just don't understand why noone in my school can explain things like this, and i have to figure out everything by myself. Thank you for this amazing visualization!!
Understanding and Teaching are two very different skill set. Some people can have gold medal in teaching but are unfortunately not in teaching profession maybe because some claim Teachers should do work out of charity or maybe because teachers can’t have incentives to improve based on the ‘views and likes’.
Back again. Now that I'm deeper into SR at uni, I realise how good this explanation is. At 2:42, the way the animation is used to describe length contraction and time dilation AND relative simultenaity is frankly perfection
I am so glad that you redid this video in HD! Your old one was actually still my "go to" for explaining SR to people and I found this while looking it up. Great!!
Awesome. A static spacetime diagram is so hard to wrap your head around, but this animation makes it feel obvious. Wish this was included in every video I had watched on the matter before..
Also notice that from the ground's frame of reference, over time, the amount of photons reaching both detectors is the same. Is the same to throw more balls at lower speed, & throw less balls at higher speeds. These videos are hidden gems of the internet, & we should treasure them as such :D
I’m gonna take Modern Physics this coming semester, so I started to watch a lecture video on RUclips and leaned about special relativity. This video is very helpful! Thank you so much! Waiting for more! This is the first channel I found in the first morning of 2023! Happy new year!🎉🎉🎉
This is SR. Time actually runs at 2 speeds in the same frame. The Time t is the same everywhere, but the time t' on a relatively moving object [ also known as clock t' ] is Different everywhere ( see t'=k [ t - vx/cc ] ). So time in one frame ticks at 2 different rates, but each frame has its own time associated directly statically with it where t = time on any objects that don't move relative to that frame - and t' is the time on objects that DO move. ie Einstein's special relativity is more complicated than he thought it was.. hence the confusion
Yaaaas it's cool this broke thru for so many (like myself). And unfortunate other RUclips explanations haven't built on this (focused on Lorentz xform). I have definitely heard reference to the notion of "rotating into the time dimension" when approaching the speed of light, which seems to pump intuition well once you get the geometry. Still, there's this uncanny feeling of yet how much simpler/clearer it can get.
I don't think the skewed comparisons at the end are right, because merely skewing the frame of reference doesn't preserve the speed of light. skewing the whole frame of reference is equivalent to the galilean transformation as opposed to the lorentz transformation you spoke about earlier. You can see the paths of light marked in yellow 'sliding' along the surface of the diagram as you switch between the frames of reference.
Yes, and the entire thing is visually... _confusing_ . I don't see the bulk of comments' praise for the outcome; it's far below my satisfaction level for their introduction to Tensors.
It's because of the way the diagram is scaled. It's common to scale these diagrams such that 1 space unit is equal to the distance light travels in 1 time unit. So for example we can think of the time units as seconds, and the space units as light-second. A 45 degree line means the particle is travelling 1 unit of space per 1 unit of time, which is light speed in this case.
Wait, did I just watch a 4.5 minute video sumarising perfectly what books and maths have been trying to explain to me for years. I got the "oh, yes, got it now!" moment
Classical physics still works if you take into accout the fact that you can only measure 2C, and never C directly. Which means speed of light can go faster in one direction and slower in the other direction to compensate. So If you take that into account and you assume that speed of light is the speed of information (ie: it applies to all forces), then you also have slowing and speeding up clocks in classical physics
Isn't this incorrect? During the final animation at 3:36, the Ground's frame of reference depicts the photons traveling right as going slower and left as going faster - but the whole point is that every observer should be seeing photons travel at the same speed no mater what. There should be no view where some photons look faster than the other.
They're moving at the same speed. It looks like the right ones are going slower because we tend to compare them with the nearest object which is the cart. Check the same scene at 3:14, where we also draw a diagram. It shows the world lines are both slanted by 45 degrees.
@@udiprod Ahhh okay I think if I stare at the ground during 3:36 i can kinda see it. I might recommend that there's an example where the cart moves a bit slower, or that there's a brief "stopwatch"+"distance" measurement in that portion - to an untrained eye, it does first like it goes against the explanation of the constant speed of light.
If the author of the video has to go and explain the meaning of a video, then something went wrong. I've gone back and forth through the thing and it has the fatal "going over the visual pedagogical cliff at" around point 2:40.
This gets confusing, though. Say that you've connected a circuit to both detectors. The circuit will light up a green light if both detect light at the same time, and a red one otherwise. Would the ground observer see a red light and the cart one, a green one? If the light remains active and the cannon stops shooting once it's lighted up, what if the cart stops moving and the observers check what color it is? It can't be red AND green, it must be one of the two. So what exactly happens?
This is a fantastic thought experiment! I'll start with the answer: both reference frames will see green (ignoring red/blue shift of course as that's clearly not your point). Why? The circuit theory you used to predict the behavior of your device is an inherently _non-relativistic_ theory, and is a simplification of Maxwell's equations applied to a rest frame. In other words, once your circuit is observed from a different relativistic frame, the rules you followed to make it work in your rest frame no longer apply. Instead, you would have to now predict its behavior by re-solving Maxwell's equations (not circuit theory) in the new frame, and you would find that the new predicted behavior conveniently differs in just such a way that it preserves the end result. Electric and magnetic fields interchange depending on your reference frame, and so the _circuit itself_ changes when observed in different reference frames.
@@OilyLagrunge oh, i think i get it. It could be explained because the voltage isn't applied instantaneously to the whole circuit, but at the speed of light. At the ground reference frame, it would be equivalent to the photons being reflected off the detectors and reaching the circuit's light, at least in simple terms. And in complex terms, it's what you said, the way electromagnetic fields form is different, thus both referentials have the same result. Thank you for explaining!
@@jakistam1000 Just learn the matrix format of Lorentz Transformation, and just see how that transforms the coordinate system. That's what special relativity encapsulates.
@@Diaming787 Yeah, but that's not the point. The original commenter asked how did this video explain the topic, and I pointed out that it didn't. It showed some useful intuition, but this video alone doesn't teach anyone to perform Lorentz transformation.
@@C4pt41nN3m0 What you're saying is true, and I'm not saying that this video is bad. But the original comment was about explaining the concept " in 4½ minutes [when] my teachers couldn’t [explain it] in ¼ year". These types of comments very often appear under educational RUclips videos, but they're just not a fair comparison. The task of the teacher is not just to explain the general concept, but to also teach their students the math behind it, and how to apply it. In good courses, it often includes the derivation of Lorentz transformation from the assumption of constant speed of light, which takes time. And then, once the math is there, you need to do many examples to actually get comfortable with using the concepts you just learned in a correct way. Additionally, the video can be stopped, pondered upon, and played back multiple times. During the lecture, you can't re-wind time; if something needs repeating, the teacher actually needs to spend time repeating that. Also, the class is presented to multiple students, which means that some of them might have follow-up questions and/or require the concept to be explained again, in a different way. This video might actually not be a great explanation to some people, but those people are much less likely to leave a comment (or follow this channel in the first place), so we're dealing with selection bias here. On top of all that, in university courses, you're learning multiple different subjects at the same time; and you have lots of time off. This "4½ minutes vs ¼ year" comparison would, when interpreted in a naive way, suggest that the teaches spends 30000 times as much time on the subject as the video; but realistically, it would only be 100-200 times as much time; which, when paired with other problems mentioned before, isn't as unbelievable. I am aware of the fact that bad teachers exist. But the direct comparison of RUclips demonstration video with a proper course in the subject is just not appropriate. There are actual videos that explain this and other complex subjects in detail, including the mathematics (on RUclips and elsewhere), but their total length is comparable to the length of the lectures, and they still require pausing and working through examples for full comprehension.
Seem fun! When the speed of the car reaches that of the light, the Lorentz transformation quadrilateral region in the grid becomes a slanted line with 45 degrees. Does it suggest the left detector always receives the photon without any delay and the right one receives nothing all the time if we stand at the ground frame?
"Experimental evidence" we did once. yeh, I remember that trip to Paris we made at the speed of light and this is exactly what happened... Atomic clocks utilize a piezo-electric resonator that enters new space as it moves, experiencing field alterations that a stationary one doesn't. The results showed "approximations" to significant values, not precise ones . If you mean those "experiments", overruled.
What people don't understand about light is that it's speed might be constant but it's frequency changes. Foe objects in motion to keep rhe same timing, you just have to adjust the frequency of light. This is what GPS clocks do. They are initially calibrated to measure X distance and are now measuring Y distance. Adjust the frequency of light to match the new speed and 'time-dilation' goes away. The problem arises when you apply the change in force due to a change in distance traveled in the space frame to the time frame of reference. E=mc. Biological clocks automatically adjust frequencies to account for the change in force. Mechanical clocks don't. In this example, if you imcrease the distance the photon has to travel, decrease the photon's wavelength so it doesn't have to travel as far. You need to quit marketing SR as time-dilation because it's not. It's just a change in force which can be easily compensated for by recalibration.
I don't understand why, in the classical physics example, the photons have a different speed when the cart is moving. If I fire a gun while I am standing on a moving cart, then from the ground's perspective, the bullet will move at the same speed as it would if the cart was standing still.
think about a car driving at 120mph, then you throw a tennis ball forward. The tennis ball will be moving at 120mph + some extra, which is much faster than you could normally throw it while standing still
There's not a single phenomenon of the three--distance, time, and simultaneity, skewing--that this video has helped my to understand. After around 2:46 I'm hopelessly lost. Perhaps it would have been better to have selected a more modest fraction of c for our (relativistically) 'moving' cart; with the photon path absurdly lengthened to the point of passing below the video boundary itself, the thing totally lost me, and no amount of verbal commentary was helping. The length contraction comes the closest to visual explanation, but only in terms of the what. The how and why of the compression of the time-line boundaries just isn't there. I'm wondering now if the visual paradigm itself is flawed.
There are very clearly photon paths that are not cut off by the screen, it's kind of the whole point of the visualization to show how much the transformation warps the movement, and thus gives us context as to why the other frame of reference makes us see what appears to be incorrect movement. This isn't a lecture on the mechanics of the transformation, it's a 4 minute visualization.
So... you forgot dimensions stretching. For each point of view photons moving with the same speed of light, but the distances changes (this is true only for photons). For another objects changes space + time. Relativity theory is some mix with space, time and speed. If you are looking for photons than speed = const, and changes space + time. It's more harder to understand than it looks like in the video.
Wait, so this means that it's impossible for two people to have the exqct same perspective of one object, at exactly the same time? This makes me wonder about the true perspective that lets you see all possible human perspectives of one object at the exact same time. To do so, you'd have to travel up dimensions, same way you made a cart on a one dimensional plane into a 2d representation with time on the y axis
Which law of classical physics would say that a massless photon would move according to the speed of the speed of the device that generated it? That makes sense if you're shooting an object, since the object already exists and its mass is moving at the same speed of the device in which it is contained. But a photon? Light doest care about the speed or direction of the device at all. Assuming it would care is a wrong assumption in classical physics, if such an assumption actually exists.
If we take into acount that a there is a central observer then everything makes more sence, since the ligth have to travel from the ligthgun to the sensors and fron the sensors to the observer, in both frames of referencie, the observer will not see the photons traveling from the bun to the sensors or traveling fron the sensors to the observer but the ligth tha te observer recives, finally, a photton travelling towards the sensor and then backwars to the observer have the same distance to travel than a pgoton travelling backwards to the sensor and then foward to the observer, with this: a+b=b+a
its the same with sound waves through a medium. speed can NEVER change time, the only thing that could is acceleration force. please everyone do your homework correctly
![BLACK BAG - Official Trailer [HD] - Only in Theaters March 14](http://i.ytimg.com/vi/Du0Xp8WX_7I/mqdefault.jpg)
This is great!
nice to see a great youtuber watching another fellow great youtuber
Can you perform the fizeau experiment to verify that light travels at a finite speed?
From 15 years of RUclips, I still have this guy at the top of the true quality list. Many people don't like the halting problem one because they don't understand the implications of the simply proof. It's actually one of my favorite, though. I am glad he redid this one, for sure, because the 15 year old version of this video was one of my favorite videos, for usefulness, of all time.
babe wake up udiprod posted
Fax😹😹
Bruh honestly
New to this. Fantastic
I've never been more excited to see a 14 year old video, now in HD
This was a topic that took me longer than I'd like to admit to understand the first time I was learning it, and this video makes spacetime diagrams so easy to comprehend. 10/10
I never expected anyone to visualise special relativity in such concise way and you have blown my mind away !
This is just a remake of his 15 year old video, but in higher quality resolution. I'm not sure if there are other minor changes.
One thing i would recommend to videos like this with slow stable panning animations is to render it at 120fps and encode the video as 60fps to avoid jitter and trembling. It's hard to watch certain parts of it at low framerate. Since this is all simple 3D renders i don't think i changes anything about the workflow other than having to wait a bit longer for the video to export.
Only true udiprod fans know that this video is a remastered version of one they uploaded almost 15 years ago! Amazing work guys, keep it up ❤
I just don't understand why noone in my school can explain things like this, and i have to figure out everything by myself. Thank you for this amazing visualization!!
Understanding and Teaching are two very different skill set.
Some people can have gold medal in teaching but are unfortunately not in teaching profession maybe because some claim Teachers should do work out of charity or maybe because teachers can’t have incentives to improve based on the ‘views and likes’.
Back again. Now that I'm deeper into SR at uni, I realise how good this explanation is. At 2:42, the way the animation is used to describe length contraction and time dilation AND relative simultenaity is frankly perfection
Was wondering about something similar before, can't stress enough how thankful I am for you posting this video!!
I am so glad that you redid this video in HD! Your old one was actually still my "go to" for explaining SR to people and I found this while looking it up. Great!!
i dont care about science at all, but i just find a lot of joy in these videos.
This was one of my favorite videos of yours, I'm glad you guys did a remake!
This channel is crazy bruh how do you make such complicated concepts so simple. Amazing
Awesome. A static spacetime diagram is so hard to wrap your head around, but this animation makes it feel obvious. Wish this was included in every video I had watched on the matter before..
Also notice that from the ground's frame of reference, over time, the amount of photons reaching both detectors is the same. Is the same to throw more balls at lower speed, & throw less balls at higher speeds. These videos are hidden gems of the internet, & we should treasure them as such :D
Very clear explaination. Thank you!
Oh man, It's been a long time since I saw this! Glad you got to clean it up a bit.
Nicely done! This fascinates me not only about the topic itself, but how this channel easily breaks down meticulous topics.
I’m gonna take Modern Physics this coming semester, so I started to watch a lecture video on RUclips and leaned about special relativity. This video is very helpful! Thank you so much! Waiting for more! This is the first channel I found in the first morning of 2023! Happy new year!🎉🎉🎉
awesome stuff, only the last overlayed animation was a little hard to look at
The best visualisation I have seen!
The Rocker Spaniels have been wandering for nearly 15 years now...
I wonder if the drummer is getting tired of carrying that drum kit yet.
babe wake up new udiprod video
Fascinating channel just come across. To the 9yr old merge sort animation, its really good.
This hurt my brain more than normal from your videos. Thank you
Fantastic visualization
absolutely fantastic, this should be shown to all physics students
Thanks, this is great. Can't wait to see your next demonstration.
What a great video
From a ground observer’s point of view of course
so, basically, the ground sees the past and the present at the same time. Cool!
This is SR. Time actually runs at 2 speeds in the same frame. The Time t is the same everywhere, but the time t' on a relatively moving object [ also known as clock t' ] is Different everywhere ( see t'=k [ t - vx/cc ] ). So time in one frame ticks at 2 different rates, but each frame has its own time associated directly statically with it where t = time on any objects that don't move relative to that frame - and t' is the time on objects that DO move.
ie Einstein's special relativity is more complicated than he thought it was.. hence the confusion
Yaaaas it's cool this broke thru for so many (like myself). And unfortunate other RUclips explanations haven't built on this (focused on Lorentz xform). I have definitely heard reference to the notion of "rotating into the time dimension" when approaching the speed of light, which seems to pump intuition well once you get the geometry. Still, there's this uncanny feeling of yet how much simpler/clearer it can get.
Can you explain a bit more about it? I'm struggling to get the intuition for Lorentz transformation
I hate to say this but you need more subs
The best part in this video was the Rocker Spaniels walking at the end
This explains everything so well! Thanks for this video
wow, beautiful visualization.
I don't think the skewed comparisons at the end are right, because merely skewing the frame of reference doesn't preserve the speed of light. skewing the whole frame of reference is equivalent to the galilean transformation as opposed to the lorentz transformation you spoke about earlier. You can see the paths of light marked in yellow 'sliding' along the surface of the diagram as you switch between the frames of reference.
Yes, and the entire thing is visually... _confusing_ . I don't see the bulk of comments' praise for the outcome; it's far below my satisfaction level for their introduction to Tensors.
That's a wonderful demostration
Help me please! I don’t understand why the 45 degree lines at 1:41 indicate the photons are moving at speed of light
It's because of the way the diagram is scaled. It's common to scale these diagrams such that 1 space unit is equal to the distance light travels in 1 time unit.
So for example we can think of the time units as seconds, and the space units as light-second.
A 45 degree line means the particle is travelling 1 unit of space per 1 unit of time, which is light speed in this case.
Wait, did I just watch a 4.5 minute video sumarising perfectly what books and maths have been trying to explain to me for years. I got the "oh, yes, got it now!" moment
great visualization! Thank you!
New Einstein lore just dropped
I very much enjoy the marching band at the end
Fantastic explanation!
If the photon moves at the speed of light, the detectors have to be 300,000 km away, because it detects it in one second...
Wow ! This video is awesome . Thank you !
Classical physics still works if you take into accout the fact that you can only measure 2C, and never C directly. Which means speed of light can go faster in one direction and slower in the other direction to compensate.
So If you take that into account and you assume that speed of light is the speed of information (ie: it applies to all forces), then you also have slowing and speeding up clocks in classical physics
Loved it. Thank you so much!
awesome video. thanks so much
Isn't this incorrect? During the final animation at 3:36, the Ground's frame of reference depicts the photons traveling right as going slower and left as going faster - but the whole point is that every observer should be seeing photons travel at the same speed no mater what. There should be no view where some photons look faster than the other.
They're moving at the same speed. It looks like the right ones are going slower because we tend to compare them with the nearest object which is the cart. Check the same scene at 3:14, where we also draw a diagram. It shows the world lines are both slanted by 45 degrees.
@@udiprod Ahhh okay I think if I stare at the ground during 3:36 i can kinda see it. I might recommend that there's an example where the cart moves a bit slower, or that there's a brief "stopwatch"+"distance" measurement in that portion - to an untrained eye, it does first like it goes against the explanation of the constant speed of light.
If the author of the video has to go and explain the meaning of a video, then something went wrong. I've gone back and forth through the thing and it has the fatal "going over the visual pedagogical cliff at" around point 2:40.
Fantastic video
Un video perfecto, otra vez. Gracias! (-una pirata de turquia)
Absolutely stunning❤
What happened to The Rocker Spaniels? It’s been 8 years! (2014)
This is excellent thank you so much
Nifty ! As always
This gets confusing, though. Say that you've connected a circuit to both detectors. The circuit will light up a green light if both detect light at the same time, and a red one otherwise. Would the ground observer see a red light and the cart one, a green one? If the light remains active and the cannon stops shooting once it's lighted up, what if the cart stops moving and the observers check what color it is? It can't be red AND green, it must be one of the two. So what exactly happens?
This is a fantastic thought experiment! I'll start with the answer: both reference frames will see green (ignoring red/blue shift of course as that's clearly not your point). Why? The circuit theory you used to predict the behavior of your device is an inherently _non-relativistic_ theory, and is a simplification of Maxwell's equations applied to a rest frame. In other words, once your circuit is observed from a different relativistic frame, the rules you followed to make it work in your rest frame no longer apply. Instead, you would have to now predict its behavior by re-solving Maxwell's equations (not circuit theory) in the new frame, and you would find that the new predicted behavior conveniently differs in just such a way that it preserves the end result. Electric and magnetic fields interchange depending on your reference frame, and so the _circuit itself_ changes when observed in different reference frames.
@@OilyLagrunge oh, i think i get it. It could be explained because the voltage isn't applied instantaneously to the whole circuit, but at the speed of light. At the ground reference frame, it would be equivalent to the photons being reflected off the detectors and reaching the circuit's light, at least in simple terms. And in complex terms, it's what you said, the way electromagnetic fields form is different, thus both referentials have the same result. Thank you for explaining!
@@hello-hb1ll Exactly! You summed it up even better lol. Glad I could help, it's a cool thought experiment that I don't think I've heard before.
How can it be that you explained something to me in 4½ minutes my teachers couldn’t in ¼ year?
Partially because it's not a full explanation? Just by watching this video, you won't learn how to apply the Lorentz transformation.
@@jakistam1000 Just learn the matrix format of Lorentz Transformation, and just see how that transforms the coordinate system. That's what special relativity encapsulates.
@@Diaming787 Yeah, but that's not the point. The original commenter asked how did this video explain the topic, and I pointed out that it didn't. It showed some useful intuition, but this video alone doesn't teach anyone to perform Lorentz transformation.
@@C4pt41nN3m0 What you're saying is true, and I'm not saying that this video is bad.
But the original comment was about explaining the concept " in 4½ minutes [when] my teachers couldn’t [explain it] in ¼ year". These types of comments very often appear under educational RUclips videos, but they're just not a fair comparison.
The task of the teacher is not just to explain the general concept, but to also teach their students the math behind it, and how to apply it. In good courses, it often includes the derivation of Lorentz transformation from the assumption of constant speed of light, which takes time. And then, once the math is there, you need to do many examples to actually get comfortable with using the concepts you just learned in a correct way.
Additionally, the video can be stopped, pondered upon, and played back multiple times. During the lecture, you can't re-wind time; if something needs repeating, the teacher actually needs to spend time repeating that. Also, the class is presented to multiple students, which means that some of them might have follow-up questions and/or require the concept to be explained again, in a different way. This video might actually not be a great explanation to some people, but those people are much less likely to leave a comment (or follow this channel in the first place), so we're dealing with selection bias here.
On top of all that, in university courses, you're learning multiple different subjects at the same time; and you have lots of time off. This "4½ minutes vs ¼ year" comparison would, when interpreted in a naive way, suggest that the teaches spends 30000 times as much time on the subject as the video; but realistically, it would only be 100-200 times as much time; which, when paired with other problems mentioned before, isn't as unbelievable.
I am aware of the fact that bad teachers exist. But the direct comparison of RUclips demonstration video with a proper course in the subject is just not appropriate. There are actual videos that explain this and other complex subjects in detail, including the mathematics (on RUclips and elsewhere), but their total length is comparable to the length of the lectures, and they still require pausing and working through examples for full comprehension.
What happened to the rocker spaniels though?
Why was I never taught this in highschool and now I'm leaning things 7 years later
Amazing stuff!
Seem fun! When the speed of the car reaches that of the light, the Lorentz transformation quadrilateral region in the grid becomes a slanted line with 45 degrees.
Does it suggest the left detector always receives the photon without any delay and the right one receives nothing all the time if we stand at the ground frame?
Thanks, congratulations,very interesting,greetens from México City👍🇲🇽🌈
babe wake up new udiprod video just dropped
So CxC=C² is each square in space-time diagram, that square(surface)xMess(height)=Energy(a 3D box in the space-time diagram)?
"Experimental evidence" we did once. yeh, I remember that trip to Paris we made at the speed of light and this is exactly what happened... Atomic clocks utilize a piezo-electric resonator that enters new space as it moves, experiencing field alterations that a stationary one doesn't. The results showed "approximations" to significant values, not precise ones . If you mean those "experiments", overruled.
1:03 dash pad from sonic?
Nice, the transformation appears to be correct for a Lorentz factor of 1.666_.
Are the Galilean and Lorentz transformations linear?
New video yay
What people don't understand about light is that it's speed might be constant but it's frequency changes. Foe objects in motion to keep rhe same timing, you just have to adjust the frequency of light. This is what GPS clocks do. They are initially calibrated to measure X distance and are now measuring Y distance. Adjust the frequency of light to match the new speed and 'time-dilation' goes away.
The problem arises when you apply the change in force due to a change in distance traveled in the space frame to the time frame of reference. E=mc. Biological clocks automatically adjust frequencies to account for the change in force. Mechanical clocks don't.
In this example, if you imcrease the distance the photon has to travel, decrease the photon's wavelength so it doesn't have to travel as far.
You need to quit marketing SR as time-dilation because it's not. It's just a change in force which can be easily compensated for by recalibration.
So, to a non-moving viewer, would the cart look elongated?
Contracted. A viewer in the ground sees the cart as shorter. And a viewr in the cart would see everything on the ground contracted.
Thanks for the explanation and for leaving me even more confused
This is unrelated to the video, but did you get my follow-up email to the email you sent me?
Wait never mind, you did reply, although it was in June.
Guess I can stay awake for a few more minutes
What experiments are you referring ?
I don't understand why, in the classical physics example, the photons have a different speed when the cart is moving. If I fire a gun while I am standing on a moving cart, then from the ground's perspective, the bullet will move at the same speed as it would if the cart was standing still.
think about a car driving at 120mph, then you throw a tennis ball forward. The tennis ball will be moving at 120mph + some extra, which is much faster than you could normally throw it while standing still
@@dabs4270 Makes sense! Thank you for your answer.
A certified classic
Somehow I think just blind faith in the numbers is the only way that I can understand it
I swear I saw this 10 years ago.
You probably did. He cleaned up his old video and added better narration.
There's not a single phenomenon of the three--distance, time, and simultaneity, skewing--that this video has helped my to understand. After around 2:46 I'm hopelessly lost. Perhaps it would have been better to have selected a more modest fraction of c for our (relativistically) 'moving' cart; with the photon path absurdly lengthened to the point of passing below the video boundary itself, the thing totally lost me, and no amount of verbal commentary was helping.
The length contraction comes the closest to visual explanation, but only in terms of the what. The how and why of the compression of the time-line boundaries just isn't there. I'm wondering now if the visual paradigm itself is flawed.
There are very clearly photon paths that are not cut off by the screen, it's kind of the whole point of the visualization to show how much the transformation warps the movement, and thus gives us context as to why the other frame of reference makes us see what appears to be incorrect movement. This isn't a lecture on the mechanics of the transformation, it's a 4 minute visualization.
Well done.
So... you forgot dimensions stretching.
For each point of view photons moving with the same speed of light, but the distances changes (this is true only for photons). For another objects changes space + time.
Relativity theory is some mix with space, time and speed. If you are looking for photons than speed = const, and changes space + time. It's more harder to understand than it looks like in the video.
so ground observer can predict the future?
Is this a repost?
@Hypothermic Dysrhythmia ohhh
Udiprod posted!
So we’re all just gonna ignore the fact that the cart’s width is twice the distance between Earth and the moon, are we?
We assume speed of light is very slow
Wait, so this means that it's impossible for two people to have the exqct same perspective of one object, at exactly the same time?
This makes me wonder about the true perspective that lets you see all possible human perspectives of one object at the exact same time. To do so, you'd have to travel up dimensions, same way you made a cart on a one dimensional plane into a 2d representation with time on the y axis
Nice!
Admit I never understood it before I came here.
Which law of classical physics would say that a massless photon would move according to the speed of the speed of the device that generated it?
That makes sense if you're shooting an object, since the object already exists and its mass is moving at the same speed of the device in which it is contained. But a photon? Light doest care about the speed or direction of the device at all. Assuming it would care is a wrong assumption in classical physics, if such an assumption actually exists.
Brilliant!!!
Muy bueno!!
Hey you forgot the problem with the unmeasurability of the one-way speed of light. Without that nothing you say would be true.
If we take into acount that a there is a central observer then everything makes more sence, since the ligth have to travel from the ligthgun to the sensors and fron the sensors to the observer, in both frames of referencie, the observer will not see the photons traveling from the bun to the sensors or traveling fron the sensors to the observer but the ligth tha te observer recives, finally, a photton travelling towards the sensor and then backwars to the observer have the same distance to travel than a pgoton travelling backwards to the sensor and then foward to the observer, with this: a+b=b+a
its the same with sound waves through a medium. speed can NEVER change time, the only thing that could is acceleration force. please everyone do your homework correctly
Stellar
thats real good
To answer that, we need to talk about parallel univer- … wait.
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