Re: is free-fall an inertial frame?

[Stefan Jeglinski <jeglin@4PI.COM>]

> A free-fall is not an inertial frame. Assuming a spacecraft, with two
> masless objects inside, free-falling to the center of the earth, one
> should see that the distance between this two objects is diminishing
> when time is elapsing.


Read SpaceTime Physics by Taylor and Wheeler for a more detailed
explanation. How effectively free-fall can actually be used as an
inertial frame of reference depends on the size of the region of
spacetime under consideration and the accuracy of the measuring
instruments used to determine distance, which directly relates to
whether one "sees" the distance diminishing. "A free-fall is not an
inertial frame" does not appear to be an absolute truth in a
practical sense. For an object the size of the space shuttle for
example, free-fall appears to be an excellent inertial frame of
reference. I am not quoting a quantitative measure of "excellent"
because I am lazy and I haven't crunched the numbers (but
Taylor/Wheeler do).


Stefan Jeglinski