The discussion revolves around the implications of traveling 10 light-years at 75% the speed of light, focusing on the perceived time experienced by passengers aboard the spaceship and the average speed from different reference frames. Participants explore concepts from special relativity, including time dilation, proper time, and the Lorentz factor.
Participants express differing views on whether the traveler would perceive their journey as faster than light. Some assert that it would not appear so, while others highlight the complexities of how time and distance are measured in different frames, indicating that the discussion remains unresolved.
Participants note the limitations of using measurements from different reference frames to calculate speed, emphasizing the need for clarity in definitions and the implications of special relativity.
RandallB said:shamphys
I assume you mean the statement in wiki:
" ... a constant 1 g acceleration would permit humans to travel as far as light has been able to travel since the big bang (some 13.7 billion light years) in one human lifetime. "
Would "appear" as a FTL speed or "change in location" - just remember that in SR the traveler still does not see a local FTL event at any time - and you will begin to understand what Einstein was saying with SR.
In relativity when physicists talk about an object's "point of view" they mean what's happening in the object's inertial rest frame, but light doesn't have an inertial rest frame of its own. Inertial frames are supposed to be defined by networks of rulers and synchronized clocks at rest in that frame, but it's impossible for rulers and clocks to be accelerated to the speed of light, and even if you consider the limit as they approach the speed of light, the rulers' length would approach zero due to Lorentz contraction and the clocks would approach being completely frozen due to time dilation, so you couldn't construct a sensible coordinate system out of them. One more reason that light can't have its own inertial rest frame is that one of the fundamental postulates of relativity is that the laws of physics should be the same in every inertial frame, but light can never be at rest in the rest frame of any object moving slower than light, so giving light its own rest frame would violate this postulate.shamphys said:also any chance of answer for my question about how long it takes for a pulse of light to travel 10 lyrs ,from the pulse of lights point of view