Monday, April 1, 2024

Waterfalling down the Staircase

(Reposted from Groups.io extremeprogramming group)


For those who haven't been watching 3 Body Problem on Netflix, the last episode of Season 1 includes a resounding lesson about the difference between Waterfall and Agile.   (It would be great if someone with more video savvy than me were to capture the clip and link to it here.)

The Staircase Project is the old Project Orion concept reimagined to send a probe to recon an alien enemy fleet many light years away. Without going into spoilers, the basic idea is to accelerate a probe with an EM sail to near light speed by shooting it past 300 nuclear bombs, each to be exploded at just the right moment to blast it with radiation.  This is a purely ballistic launch: the probe has no power or steering capabilities, so the explosions have to be timed perfectly and the trajectory is locked in.

Sounding familiar? 

Early on, the shock of an explosion disconnects one of the tethers connecting the probe to the sail, the probe goes off course, and the entire project is lost - a world-threatening catastrophe.

It would not have been rocket science to give the probe the minimal intelligence and power to adjust its trajectory, perhaps by "trimming" the sail with a tug on one of its many tethers.  But no: the finest minds on earth agree it's necessary to lock the trajectory in up front.

(Disclaimer - I've read only the first book in the trilogy on which the series is based, which ends before the probe project is undertaken, so I don't know if the author, Liu Cixin, is responsible for the waterfall.)