If you observe the formation of cloud chamber tracks, it appears that
the track "grows" in the direction of motion of the charged particle
that caused it. Here's my question: Since these are high speed
particles and traverse the cloud chamber in what must be microseconds
or less, why doesn't the entire track appear simultaneously? Why
does it (at least appear to) get seeded at one end and grow in the
direction of the particle motion on a time scale of milliseconds or
longer? Wolfgang