Recent content by Sean Pan

Thanks a lot and I have a clearer understand of this problem now. I actually knew that if there were FTL particles, causality would be violated. My opinion is that FTL observers can never actually traveling backwards. And thanks for all above that I now understand what other physicsts mean when...

Thanks for all of you above. When treating FTL particles, does Lorentz Boost still make sense? Anyone have studied that?

Can you show me how can an observer travel to its past when its speed is over the speed of light? As mathematics fails here ,I prefer using space-time diagram to discribe this kind of situation. In this way, in a certain reference system the world line of the object moving with its speed over c...

Could you please explain why this comes out of the geometry of relativity. I think exceding the speed of light can only "observe" events happened in the past as can be easily found by drawing a space-time diagram, but it seemed that they still can't return to the past.

Your opinion on"exceeding the speed of light means the ability to return to the past" I personally think this assertion is absurd, so I'm wondering why so many people(including physicists) think this is true.

The presence of dark matter halo is detected through gravitational lensening effect of a galaxy, whose luminous portion are robbed away by another galaxy . So the idea of dark matter becomes more prevailing than theories modifying the expression of Newtonian gravity on large scales.

Hope so, as the sample of exoplanets goes larger, more details about planets can be revealed. If your idea is reasonable, there may be more similarities between stars having planets possible of forming life.

Thanks a lot for your very detailed analysis!

Thanks, but there are many processes in the forming of stars that can reduce the angular momentun of the centural stars. Maybe I should have paid more attention to its initial angular momentum, but other factors should also be considered. Since star forming last a very long time, I think the...

It is said that massive stars spin faster than less massive ones and I am always wondering why.Could someone please tell me the reason? Thanks a lot.