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RE: starship-design: Relativity



I was in Chapter 5, specifically, Figure 5-8. It seems illogical that the
worldline indicated could approach zero, but that does seem to be what is
represented.

Lee

> Is this in reference to a particular exercise or passage in _Spacetime
> Physics_?  If so, which one?  It would help me understand the context.
> I hope you have the second (1989) edition; otherwise it may be a bit
> hard to connect with the copy I have.
>
> It depends on what you mean by "the length of the worldline".  The
> definition that is invariant for all observers is that the "length" of
> the worldline (typically called the interval in _Spacetime
> Physics_) is
> is equal to the elapsed time experienced by the object that travels
> along that worldline between event A and event B.  Depending on their
> relative velocities to that object other observers will see
> event A and
> event B as being different distances from each other and the object as
> taking different amounts of their time to travel from event A to event
> B.  The ratio between the amount of time shown on a clock carried with
> the object and the amount of their time they measure for the passage
> from point A to point B goes to zero as the relative velocity of the
> object approaches c.