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愛因斯坦 的 隔籬飯香

「隔籬飯香」的意思是「你睇我好,我睇你好。」 愛因斯坦的版本是「你睇我好慢,我睇你好慢。」

In special relativity theory, for two persons traveling at "constant velocity" relative to each other, the clock with the other person would always observed to be running slow. Consequently, the person with a slow clock would also observed to be acting sluggish and aging slow. You may be wondering how is it possible that each observes the other to be aging slow? Who actual ages slower?

Consider a 你睇我,我睇你「互睇」experiment with Abe and Bea. Abe and Bea are facing each other. One or both of them start stepping backward continuously. From Abe's view point, Bea is getting smaller. From Bea's view point, Abe is the one getting smaller. We intuitively accept the fact that they both can see the other person appears to be getting smaller without seeing themselves to be any different. We understand this to be a matter of "point of view and perspective."

發表於 Posted on: 2016-10-14 5:26

NocturnalCrawler
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In certain way, Einstein's time measurement is similar. "Point of view" in relativity theory is the "inertial frame" (慣性系). For a person within an inertial frame, everything would seem normal to that person. Size, time, aging, etc. When observing things situated in another inertial frame, things could appear different. Smaller, slower, etc. In the 互睇 experiment, the bigger the separation distance, the smaller the other person is seen to be. In relativity theory, the bigger the relative velocity, the slower the other clock is measured to be. So, the question "Who would age less in a year?" has no meaning because it depends on whose clock you use to define that one year.

Neither clock is right to the other, and neither clock is wrong to the owner. They are just different. Only by correlating for the spatial differences can one determines the true size of others. Only by correlating for relativity can one determines the true rate of progression of others.

發表於 Posted on: 2016-10-14 5:36

NocturnalCrawler
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For twins Jay and Kay, after Jay returns from a high speed round trip to a distance planet, he would be found to be younger than Kay. How is this different from Abe and Bea traveling at "constant velocity" relative to each other?

An "inertial frame" is a non-accelerating frame. Without acceleration, one feels nothing. With that, Abe and Bea see themselves to be stationary and their experiences are symmetrical. To make a round trip, Jay has to change his velocity to reverse back to earth. The moment Jay changes his velocity, he is changing his inertial frame. That is when Jay sees Kay's "present/現在/而家" accelerates ahead resulting in Kay not being observed by Jay to have aged less. Kay, without changing inertial frame throughout Jay's trip, observes Jay to have aged less.

Unfortunate for Jay, he wouldn't feel any younger. He only sees Kay to have gotten older. One does not see the peculiarity within oneself but is always keen on those of others.

發表於 Posted on: 2016-10-14 5:47

NocturnalCrawler
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