Remember when you partied and it was 1999? As the clocks ticked inexorably towards midnight, so too imminent doom approached in the form of the so-called Millennium Bug. Who knew what catastrophes would ensue as the new century began and computers all over the world went into meltdown, unable to cope with a quadruple-digit date change?
In the event, no nuclear reactors went critical, planes remained in the sky, supermarket doors opened on time, and humanity rubbed its collective head and got on with the traditional January 1 business of clearing out the empties, setting resolutions, and praying for a decent James Bond film in the afternoon. In the public consciousness, the abortive apocalypse was filed away as a pointless (if highly lucrative) beano for the IT industry. Nothing more to see here.
But absence of evidence doesn't equate to evidence of absence. The threat was real, and it took months (and in some cases years) of detailed toil and planning as well as huge investment to achieve the net result - so far as the general public was concerned - of no noticeable change.