Nathan123 said:
Thanks for your help. But we will have to close this. Some of the points being made are currently beyond what I have learned about SR, and some of the points I am making are not comming across. So it makes no sense to take this further.
One parting point to think about. If i see something moving, I will see it contracted. I do not need a second frame of reference for this phenomena. This is not analogous to time dilation where I need to include a second frame of reference. This is the basis for the difference I was trying to offer. I may be wrong about what I said, but I am not sure.
I know that you have decided to drop things here, but I'm going to add one more post anyway. (mainly because I went to the trouble of creating the following animations, and I don't want to feel like I wasted my time entirely.)
We have the Earth (blue sphere) and the ship (green cone). The white lines are 6/10 of a light year apart as measured by the Earth. Both Earth and ship have a clock, and I've added a third clock at the right white line.
In the first animation, we show events according to the Earth rest frame. As the nose of the ship touches the right line, its clock reads zero, as does both the Earth clock and the right line clock. (I paused the animation here so make this clear)
The ship moves from right to left at 0.6c.
This takes 1 yr in this frame as shown by the times ticking off on the Earth and right line clocks. The ship clock is time dilated, ticks 0.8 as fast, and thus reads 0.8 years upon reaching Earth. The animation is paused again before repeating so the final clock values can be easily noted.
The same events according to the ship:
Now it is the Earth, and right line moving to the left. The ship still starts at the right line, reading zero, while the clock at the right line also reads zero.
The right line and Earth are however now 0.8 x .6 = 0.48 ly apart. At 0.6 c, it will take 0.8 yrs for the Earth to reach the ship, and thus the ship clock reads 0.8 yrs when they meet.
During that time, the ship will measure both the Earth and right line clocks as ticking at a rate of 0.8 as fast as his own, and accumulating 0.8 x 0.8 = 0.64 yr. (if the right line didn't leave the animation, you would see it reading 0.64 yr when the Earth reaches the ship.) Even though the Earth clock only accumulates 0.64 yr between the time the right line leaves the ship's vicinity and the Earth arrives, its clock still reads 1 yr upon arrival. This because, due to the relativity of simultaneity, It does not read 0 when the ship and right line are adjacent to each other, but already reads 0.36 yrs.
In the Earth rest frame, the events of the Earth clock reading zero and the right line clock reading zero are simultaneous, while in the rest frame of the ship, they are not. The Earth clock reads 0.36 yr ahead of the right line clock.*
* we will assume that the ship and Earth had a constant 0.6c relative velocity even before the events shown here. In other words, in the Earth frame, the ship comes in from the right edge of the animation at 0.6 c, and then starts its clock from zero when it passes the right line. The Earth clock also starts running from zero at this moment according to this frame. In the ship frame, the ship still starts its clock from zero when passing the right line, but the Earth clock will have already been running, having started at zero some time before that moment.
