Mechanics 2: Linear and Rotational Dynamics - 3D Math Primer for Graphics and Game Development - page 559

Figure 12.2. An alien watching the elevator fall as Earth moves past will not see anything to
contradict Newton's three laws, assuming the time period is short enough so that
Earth's rotation and curved path are not significant factors.
A viewer on the ground would not see any need to invent a fictitious
force to explain the sandwich's behavior. Using a reference frame with the
origin fixed at the bottom of the building, the viewer sees the sandwich as
accelerating downward, and has no reason to think anything is amiss. 3 The
person driving by in a car also doesn't see any problems. In the reference
frame of the car, the sandwich appears to travel in a parabolic motion.
But the relation f = m a seems to hold, and so the driver observes that
Newton's laws are valid in her reference frame. Likewise for the advanced
alien civilization watching from their cloaked spaceship as Earth whizzes
past (see Figure 12.2). From their 4 perspective, everything seems to be
obeying Newton's laws. To the alien, Earth is moving with a constant
linear velocity and the elevator's trajectory is parabolic, just as we would
predict using the projectile equations developed in Section 11.6. (Actually,
we are ignoring some finer points, such as Earth's rotation, the curved path
it takes as it orbits the sun, and the do-si-do it does with the moon. These
deviations from constant linear velocity are the exceptions that prove the
3 Aside from a falling elevator that is about to crash to the ground.
4 His/her/its. . . since aliens are just as likely to have three genders as two, the limita-
tions of the English language are not up to the demands of interstellar political correct-
ness. If there are any aliens reading this topic, please note that we tried, and therefore
do not atomize our planet. We are quite fond of it.