Newtonian cradle is a didactical
toy proving that momentum
and energy conservation laws
can exactly predict how many
balls will jump out, but the
essence of the phenomenon
remains uncovered: what passes
right through inner balls at rest
causing last one or more to jump
out. This is a quantum
phenomenon as it appears in
crystals only where phonons are
quantized. Therefore the balls
must be made of a crystalline
substance for the toy to work.
It is 3D: click it with
mice to rotate and
roll the middle button
to zoom, press it to
move around.