- #1
A Dhingra
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relative velocity of light in special theory of realtivity??
hello everyone..
as per the theory of special relativity,
Postulate2:Any ray of light moves in the 'stationary' system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body.
In other words, the speed c of light is constant as seen from any and every inertial frame of reference.
But let us suppose we have a train that is presently at rest. Let there be a source of light on the top end of the train with a photosensitive screen straight at the bottom of the source. At time t=0, the train starts to move with velocity v (high velocity) in +ve x-direction, and the source is switched on for a short period of time. As seen by an observer inside the train the photosensitive screen will have mark made by light, and the path traveled by light as perceived by this observer is a straight vertical line. The same event is observed by an observer at rest with respect to he ground, will find that light struck the screen but it traveled a slant path and not a straight line. So as seen by the observer at rest the path traveled by light is slant, which could be possible only if the vector addition of velocities was done, thus making the velocity of light not the same.
Further to set this velocity same as c length and time are subject to differ in two different frames, leading to length contraction and time dilation. But this whole idea is based on basic vector addition resultant observed by the rest observer.
So how is c invariant when it gets subjected to (relative) vector addition?
Further, let's assume instead of a normal source we have a very high resolution laser beam. Here we have two possibilities, first being laser is adjusted to fall straight at the photosensitive screen as per the rest frame. In this case the moving observer should not see light falling(because laser will fall straight down and by the time it will reach the lower end of the train, the screen and the train would have got displaced from their initial position, thus no contact) or making any impact on the screen but the rest observer should as the light is falling straight. Other case being laser adjusted as per the moving frame. (This situation has turned pretty confusing! i can't explain the outcomes, but looks like they seem to show light having relative velocity...)
So please explain how is c invariant in these circumstances?
(To ensure light is unaffected by the motion of the source, i considered laser moving straight even though the source is moving..)
hello everyone..
as per the theory of special relativity,
Postulate2:Any ray of light moves in the 'stationary' system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body.
In other words, the speed c of light is constant as seen from any and every inertial frame of reference.
But let us suppose we have a train that is presently at rest. Let there be a source of light on the top end of the train with a photosensitive screen straight at the bottom of the source. At time t=0, the train starts to move with velocity v (high velocity) in +ve x-direction, and the source is switched on for a short period of time. As seen by an observer inside the train the photosensitive screen will have mark made by light, and the path traveled by light as perceived by this observer is a straight vertical line. The same event is observed by an observer at rest with respect to he ground, will find that light struck the screen but it traveled a slant path and not a straight line. So as seen by the observer at rest the path traveled by light is slant, which could be possible only if the vector addition of velocities was done, thus making the velocity of light not the same.
Further to set this velocity same as c length and time are subject to differ in two different frames, leading to length contraction and time dilation. But this whole idea is based on basic vector addition resultant observed by the rest observer.
So how is c invariant when it gets subjected to (relative) vector addition?
Further, let's assume instead of a normal source we have a very high resolution laser beam. Here we have two possibilities, first being laser is adjusted to fall straight at the photosensitive screen as per the rest frame. In this case the moving observer should not see light falling(because laser will fall straight down and by the time it will reach the lower end of the train, the screen and the train would have got displaced from their initial position, thus no contact) or making any impact on the screen but the rest observer should as the light is falling straight. Other case being laser adjusted as per the moving frame. (This situation has turned pretty confusing! i can't explain the outcomes, but looks like they seem to show light having relative velocity...)
So please explain how is c invariant in these circumstances?
(To ensure light is unaffected by the motion of the source, i considered laser moving straight even though the source is moving..)