How time dilation is possible?

[jijeesh]

How time dilation is possible, when the light velocity (and/or its direction) is independent of its source?

 

Just made a simple opengl/cpp visualization to figure this out. please correct me if I am wrong.

 

[Janus]

The velocity of light is not independent of the source, only its speed.   Velocity involves both speed and direction.   The fact that the direction the light travels does depend on the relative motion of the source is demonstrated by the phenomenon known as aberration.  In the frame in which the source is moving aberration causes it to follow a path that causes it to arrive at the mirror exactly opposite the source.   For the source, the light just appears to go straight up and straight down again.  

But each frame measures the light as traveling at c relative to itself. Thus for the frame in which the source is moving, the light  travels a longer path and takes longer to complete one circuit than it does fro someone moving with the source. 

Light doesn't require a medium.  In a vacuum there is no medium which light travels with respect to.  

[jijeesh]

thank you!, lets consider the classic example

https://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Time-dilation-002-mod.svg/660px-Time-dilation-002-mod.svg.png

assume that the distance between 2 mirror (L) is 300,000 kms, and at time = 0, the light packet start its journey, as per the diagram, after 2 seconds, the light should reach center of mirror A, by traveling 2 times D instead of L.

But,what if, the light is following the same straight vertical path for the stationary and moving observer, it should reach at a point in space where it is originated. ie, the location of mirror A when time = 0 , (the mirrors may have been moved - to the direction of its motion)

Edited January 20, 2018 by jijeesh
image

[Janus]

18 hours ago, jijeesh said:

thank you!, lets consider the classic example

https://upload.wikimedia.org/wikipedia/commons/thumb/8/8e/Time-dilation-002-mod.svg/660px-Time-dilation-002-mod.svg.png

assume that the distance between 2 mirror (L) is 300,000 kms, and at time = 0, the light packet start its journey, as per the diagram, after 2 seconds, the light should reach center of mirror A, by traveling 2 times D instead of L.

But,what if, the light is following the same straight vertical path for the stationary and moving observer, it should reach at a point in space where it is originated. ie, the location of mirror A when time = 0 , (the mirrors may have been moved - to the direction of its motion)

If light behaved as you suggest, then there would be an easy test for absolute motion.  No experiment or observation made concurs with this. 

[swansont]

On 1/20/2018 at 2:55 AM, jijeesh said:

 But,what if, the light is following the same straight vertical path for the stationary and moving observer, it should reach at a point in space where it is originated. ie, the location of mirror A when time = 0 , (the mirrors may have been moved - to the direction of its motion)

I align laser light into an optical fiber, which is roughly 1 micron in diameter (and requires alignment to a small fraction of that size, i.e. the beam must overlap the fiber port quite well), over a beam path that is perhaps a meter long. The earth is moving and rotating, so the relative alignment changes over the course of a day (i.e. moving one direction at noon, but another at midnight). But the light remains aligned into the fiber.

Light does not behave the way you suggest.