# Relativistic Rocket-Men and Foreshortened Chicken Feathers

*
This problem was first related to me in 1997 by Hu Zhou. I don’t know
where he got it. I may have elaborated on it somewhat.*

##
The set-up

A rocket moving at great speed, and a chicken barn with doors on
either end. A pilot with insecurities that bring on annoying
and dangerous displays, and a chicken farmer losing his patience just
as dangerously.

The resting length of the rocket is equal to that of the barn,
but from the rocket pilot’s perspective, the barn is foreshortened by
speed to be much shorter than the rocket, and similarly,
to the chicken farmer, the rocket is so foreshortened by
speed to be much shorter than the barn.

The pilot decides to buzz the chickens by flying through the barn,
but as he does so, the farmer teaches him a lesson.
The farmer closes both barn doors while the rocket is in the
barn (foreshortened as the rocket is, from his perspective), briefly trapping
the pilot, then opens the doors just in time to let the pilot out.

##
The punch line

But from the point of view of the pilot, the barn is shorter than his rocket.
The rocket simply would not fit inside the barn.

##
What is the solution?

In relativistic discussions, one should always be on the lookout for
hidden assumptions of simultaneity. Here, one lurks in the closure
of the barn doors: it seems they are closed at the same time, although
they are separated spatially.

While from the chicken farmer’s perspective, the barn doors may have closed
simultaneously, from the pilots perspective, first the back doors close, then
open in front of him (he is suitably alarmed by this), but then behind him
the front doors close and then open.

The chicken farmer achieves his aim, but not quite the way he may have
imagined. The rocket ship escapes the barn unscathed, chicken feathers
fluttering behind.