Smellsniffsniff,
It's not an easy concept, it was difficult for me to grasp at first as well. Light is unaffected by relativity and therefore moves at a speed of C in every reference frame. In your statement above, you contradict yourself, at first you say Light is constant then you say that the moving ant sees light moving at "C+V", it can't be both.
Almost. Remember, when dealing with relativity, we don't know for certain which object is actually in motion. Since special relativity only deals with objects in constant motion, we can't use acceleration to fix this little relativity problem (in order to determine which object is actually in motion and which one is at rest).
Therefore the best thing we can say with your example is that the ant is moving at V relative to the meterstick while the meterstick is moving at V relative to the ant. In other words, in the ant's frame of reference, the meterstick is the thing that's moving and the ant is at rest. Therefore the ant sees Light moving away at him at a speed of C.
In the meterstick's frame of reference its the ant that's moving and the meterstick's at rest. Therefore the meterstick sees light moving away from it at a speed of C.
Clearly, as you stated, there's something wrong with this...one of the objects is in motion therefore the velocity of light should increase from C in some frame of reference...but it doesn't (that is special relativity).
The videos below discuss what, and how things like length contraction and time dilation can fix that problem so that Light moves at C in all reference frame and how light will speed off at C no matter what speed you're going.
Relativistic effects are frame defendant.
http://www.youtube.com/watch?v=KYWM2oZgi4E&feature=related
This is a pretty good video. Its not apparent but it switches between the reference frame of an observer watching the spacecraft, to the frame of the person inside the spacecraft.
http://www.youtube.com/watch?v=C2VMO7pcWhg&feature=related
Another nice depiction, but harder to follow.
It's not an easy concept, it was difficult for me to grasp at first as well. Light is unaffected by relativity and therefore moves at a speed of C in every reference frame. In your statement above, you contradict yourself, at first you say Light is constant then you say that the moving ant sees light moving at "C+V", it can't be both.
But it's allready moving in velocity v so the movement on the meterstick for light measured by the moving ant is c + v. That is why the speed it escapes the ant with is c
Almost. Remember, when dealing with relativity, we don't know for certain which object is actually in motion. Since special relativity only deals with objects in constant motion, we can't use acceleration to fix this little relativity problem (in order to determine which object is actually in motion and which one is at rest).
Therefore the best thing we can say with your example is that the ant is moving at V relative to the meterstick while the meterstick is moving at V relative to the ant. In other words, in the ant's frame of reference, the meterstick is the thing that's moving and the ant is at rest. Therefore the ant sees Light moving away at him at a speed of C.
In the meterstick's frame of reference its the ant that's moving and the meterstick's at rest. Therefore the meterstick sees light moving away from it at a speed of C.
Clearly, as you stated, there's something wrong with this...one of the objects is in motion therefore the velocity of light should increase from C in some frame of reference...but it doesn't (that is special relativity).
The videos below discuss what, and how things like length contraction and time dilation can fix that problem so that Light moves at C in all reference frame and how light will speed off at C no matter what speed you're going.
Relativistic effects are frame defendant.
http://www.youtube.com/watch?v=KYWM2oZgi4E&feature=related
This is a pretty good video. Its not apparent but it switches between the reference frame of an observer watching the spacecraft, to the frame of the person inside the spacecraft.
http://www.youtube.com/watch?v=C2VMO7pcWhg&feature=related
Another nice depiction, but harder to follow.
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