Special Relativity: Train/Lightning Paradox and Simultaneity
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- Опубликовано: 16 мар 2018
- In this video, I resolve one of the common special relativity paradoxes relating to simultaneity.
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Wait...what?
Really well explained sir.....much needed it was thank you
Sir , Thanks. Because of this Paradox Enistein deduced that time slows down.. is that correct...
Please help make complete video how Einstein deduced that to explain this paradox.
Good efforts.Really enjoyed !!!
A person is 10 m apart the right glad and another 90 m apart the first so the first person sees flag on left first while the one at 90 sees 2nd flash first here too time dilates am I right the no motion how can this be possible
Man,it is awesome
How fast is the train moving? Is it close to speed of light? I mean if the train move at a speed
That is why Newtonian mechanics is a great approximation of Relativity at speeds much smaller than c.
This implies that the presence of the moving train it the cause of the apparent non-simultaneity for the person on the ground.
Sir Einstein deduced General Theory of relativity to answer another paradox as below. Please explain this in another video if possible... this goes above my head
"General relativity is a theory of gravitation developed by Einstein in the years 1907-1915. The development of general relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example, when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion: an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics. This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so. To resolve this difficulty Einstein first proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and any momentum within it. "
The person on the ground says a light strike happens before the other one. OK, but what is the difference with the classical (Newtonian) mechanics explanation ?
@@maxwellfazio5265n the Newtonian explanation, the person on the ground will see the front light strike happening before the back one TOO. There is no paradox in classical Newtonian mechanics, as it can be explained in this (short) video: ruclips.net/video/g-ZfLpeOlKY/видео.html (English subtitles available)
@ But according to Maxwell, speed of light is constant for all observers at all positions, the inconsistencies between Newtonian mechanics and Maxwell's laws of electromagnetism actually led to to give the figure out the postulates of general relativity,
See in the above experiment Einstein gave the essential postulate of time dilation , which can also be explained mathematically,
So let speed of light be C.
Now let the distance between back lighting strike of train and observer on train = 3x
Let distance between front lighting strike and observer on train = x
So since speed of light is constant, and since lighting strikes are seen simultaneously, so time is also same = t(say)
So C = C ( speed of light being constant)
-> 3x/ t = x/t( speed =distance/time)
But we know the above is not possible, as distance 3x is obviously greater than x.
Here Einstein, being the genius he is, realised that it is possible if time slowed down by a little.
So
3x/t = x/t is possible if time in second case( on right side) gets divided by three, that is time gets slowed down three times,
3x/t = x/t/3
3x/t = 3x/t
So essentially time dilated, time goes slower for the man on train, whereas for the man on ground, time remains same as he observes both lighting strikes simultaneously and he is also standing at equal distances from them, this is an important point of special relativity, the faster we move, time slows down, it becomes 0 when we reach speed of light ( which is impossible to achieve btw). I hope I have been clear enough.Thanks
@@shreshroop Thank you for your comment. You quote 2 arguments:
- the Einstein's train. It's just a "thought experiment" = a nice storytelling, but it's NOT an experience with measurements, For 100 years it has never been verified with a train, or even a rocket, why ?
- Maxwell's equations. They are confirmed only up to measurement uncertainties. If the speed of the light varies very very little (for example by 1 mm/second), you will have the impression that the speed is constant, but not. And if photon celerity varies very few (in water, it already varies a lot, why not a little in a motion frame?), this is explicable by the New-Newtonian Mechanics.
To know it, it would be necessary to repeat the Fizeau's experience with more precise measures, as explained in this video: ruclips.net/video/eNZKe-WYeYs/видео.html