RE: Travelling at the speed of light?[Question]
October 20, 2015 at 7:15 am
(This post was last modified: October 20, 2015 at 7:18 am by Alex K.)
@Rob,
Seen from your perspective, two objects can of course move with a relative speed of near or at 2*c, for example two light rays approaching each other. It is only when you go into the reference frame ("travel with") of one of the objects, that you suddenly realize that the other object, from this vantage point, does not approach you with the same, naively expected, near 2*c, but with only near 1*c.
This is because when you move with one of the objects, the distance travelled by the other object gets length-contracted, and you measure with a different time as well. The details are confusing even when you are doing the maths. Without the maths, it is almost hopeless not to run into contradictions. This is why I recommend Mermin, he manages to get as close to a consistent and correct intuitive picture of these things as I know.
p.s.
Of course you know how to do the math, but I think this is a less stressful way to get an idea how it works.
Seen from your perspective, two objects can of course move with a relative speed of near or at 2*c, for example two light rays approaching each other. It is only when you go into the reference frame ("travel with") of one of the objects, that you suddenly realize that the other object, from this vantage point, does not approach you with the same, naively expected, near 2*c, but with only near 1*c.
This is because when you move with one of the objects, the distance travelled by the other object gets length-contracted, and you measure with a different time as well. The details are confusing even when you are doing the maths. Without the maths, it is almost hopeless not to run into contradictions. This is why I recommend Mermin, he manages to get as close to a consistent and correct intuitive picture of these things as I know.
p.s.
Of course you know how to do the math, but I think this is a less stressful way to get an idea how it works.
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
Psalm 14, KJV revised edition
