Thank you! I have spent three years searching the Internet and RUclips to find a video that combines the multiple components of Relativity so beautifully. Your video is 1000x better than the dozens of others I've looked at. It should have two million views, not just two thousand.
Wonderful graphical depiction of a complex relativistic phenomena. The plashing circle is a nice visual aid to show: time dilation, length contraction and simultaneity
The basic reason is relativity of simultaneity: for any two points on a moving object, the proper time for the foremost one in the direction of motion lags behind the proper time of the rear one. So given two events with the same proper time, the rear one shows up first. Equivalently, in a Minkovski diagram the plane of simultaneity of the moving object is at an angle to that of the observing frame. The second part of the video tries to visualize how this tilted plane of simultaneity generates the real-time view.
The ultimate reason is the speed-of-light law: what propagates at the speed of light in one inertial frame must propagate at the speed of light in any other frame. Now take the arrangement of Einstein's famous train: A device emits 2 light flashes in opposite directions from the middle of the train. From the train's p.o.v. the flashes propagate at the speed of light and reach the train's front and rear simultaneously, at the same instance of the train's proper time. From the p.o.v. of another observer watching the train pass by, the flashes still propagate at the speed of light, but the one going against the train's direction of motion meets the rear faster, while the other one has to chase the front a longer time. So for this observer the proper time at the train's rear is ahead compared to the proper time at the front. And this wouldn't happen without the speed-of-light law.
Thank you! I have spent three years searching the Internet and RUclips to find a video that combines the multiple components of Relativity so beautifully. Your video is 1000x better than the dozens of others I've looked at. It should have two million views, not just two thousand.
That was mind blowing and brilliant . Please make more videos. Wow you have changed the way I look at relativity. 💞💞💞💞💞🙋🙋🙋🙋
Nicely done! The illustration using a flashing circle -> lights along the rim of an ellipse is a great teaching device
+Behfar Bastani Glad you like it, thank you!
Wonderful graphical depiction of a complex relativistic phenomena. The plashing circle is a nice visual aid to show: time dilation, length contraction and simultaneity
+Walid Nouh Thank you, much appreciated!
Why would you see the flash starting at the rear of the disc?
The basic reason is relativity of simultaneity: for any two points on a moving object, the proper time for the foremost one in the direction of motion lags behind the proper time of the rear one. So given two events with the same proper time, the rear one shows up first. Equivalently, in a Minkovski diagram the plane of simultaneity of the moving object is at an angle to that of the observing frame. The second part of the video tries to visualize how this tilted plane of simultaneity generates the real-time view.
Hmm, K. Is there some sensible reason why the forward point's proper time would lag behind the rear's?
The ultimate reason is the speed-of-light law: what propagates at the speed of light in one inertial frame must propagate at the speed of light in any other frame. Now take the arrangement of Einstein's famous train: A device emits 2 light flashes in opposite directions from the middle of the train. From the train's p.o.v. the flashes propagate at the speed of light and reach the train's front and rear simultaneously, at the same instance of the train's proper time. From the p.o.v. of another observer watching the train pass by, the flashes still propagate at the speed of light, but the one going against the train's direction of motion meets the rear faster, while the other one has to chase the front a longer time. So for this observer the proper time at the train's rear is ahead compared to the proper time at the front. And this wouldn't happen without the speed-of-light law.
Thank you.
Chris Frisella Welcome.