If it seems too good to be true ...

At the end of July news sites offered many breathless articles about a new space drive. And three weeks later? Not so much.

This, from Wired on July 31, was typical: "Nasa validates 'impossible' space drive." Or this, from ExtremeTech on August 1, "NASA tests ‘impossible’ no-fuel quantum space engine – and it actually works."

The (supposed) space drive at issue bounces microwaves around a specially shaped chamber, and in the process is said (somehow) to produce a net thrust in one direction. Th...