YuanShenhao Posted January 30, 2018 Share Posted January 30, 2018 (edited) Let‘s see the essence of things. What is speed? Firstly speed is a relative value which can only be described by reference to something. For example: Tom and jerry run race, TOM faster than JERRY 2 m / sec. How does this figure come up? TOM speed-JERRY speed = 2 m / sec, their speed reference is runway. If the race field is in space without any other reference point, including space itself. TOM's reference is only JERRY .Then you will never know how fast TOM JERRY is. Because you don't know their speed, you don't know how much time they expand relative to our planet, and you don't know who TOM and JERRY are fast or slow, you can only observe them away from them. At this point you want to analyze them whose time is slower and it's just a joke. There is no comparison without space. Edited January 30, 2018 by YuanShenhao Link to comment Share on other sites More sharing options...
Sensei Posted January 30, 2018 Share Posted January 30, 2018 (edited) In the real Universe example, in cosmic space you can observe that photons from stars are redshifted or blueshifted. https://en.wikipedia.org/wiki/Redshift https://en.wikipedia.org/wiki/Blueshift ps. Velocity is not the same as speed. Velocity is vector, speed is scalar. Edited January 30, 2018 by Sensei Link to comment Share on other sites More sharing options...
YuanShenhao Posted January 30, 2018 Author Share Posted January 30, 2018 (edited) 32 minutes ago, Sensei said: In the real Universe example, in cosmic space you can observe that photons from stars are redshifted or blueshifted. ps. Velocity is not the same as speed. Velocity is vector, speed is scalar. Ok, thanks. I mean speed here. My English is not very good. You can observe the red-shifted and blue-shifted of light, which is because the speed of light is constant. They can only show that they are close to each other, or are they far away from each other. But it doesn't know who is moving, who is faster. Edited January 30, 2018 by YuanShenhao Link to comment Share on other sites More sharing options...
Strange Posted January 30, 2018 Share Posted January 30, 2018 1 hour ago, YuanShenhao said: you want to analyze them whose time is slower and it's just a joke. It’s not a joke. The only thing that matters is their speed relative to each other. It doesn’t matter how fast they are relative to a track, the moon or Alpha Centauri. 1 hour ago, YuanShenhao said: They can only show that they are close to each other, or are they far away from each other. But it doesn't know who is moving, who is faster. Faster is, by definition, their speed relative to some third reference. So without that third reference “faster” is meant less. But why does that matter? You can say one is stationary and the other is moving. Or you can say the first one is moving and the other one is stationary. It makes no difference. https://en.m.wikipedia.org/wiki/Galilean_invariance Link to comment Share on other sites More sharing options...
YuanShenhao Posted January 30, 2018 Author Share Posted January 30, 2018 30 minutes ago, Strange said: It’s not a joke. The only thing that matters is their speed relative to each other. It doesn’t matter how fast they are relative to a track, the moon or Alpha Centauri. Faster is, by definition, their speed relative to some third reference. So without that third reference “faster” is meant less. But why does that matter? You can say one is stationary and the other is moving. Or you can say the first one is moving and the other one is stationary. It makes no difference. https://en.m.wikipedia.org/wiki/Galilean_invariance The theory of relativity has been played out. You can continue your AB dead cycle. In front of physics, there is a difficult problem to be faced: why is the speed of light not changing? Let's go on. “you can only observe them away from them” need to be modified: You can only observe that they are far away from each other. General relativity has revealed how important space-time is. The distorted space-time is a kind of geometric effect, and we must attach importance to the existence of space. Let us continue, and my next topic will be general relativity. Link to comment Share on other sites More sharing options...
Strange Posted January 30, 2018 Share Posted January 30, 2018 1 hour ago, YuanShenhao said: The theory of relativity has been played out. I don’t think your lack of understanding is going to affect the science. 1 Link to comment Share on other sites More sharing options...
swansont Posted January 30, 2018 Share Posted January 30, 2018 3 hours ago, YuanShenhao said: The theory of relativity has been played out. You can continue your AB dead cycle. ! Moderator Note Stop posting this nonsense in the mainstream sections. If you have a beef with some theory, present it in speculations. And you need to present more than your misunderstanding of the science. Link to comment Share on other sites More sharing options...
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