florescent_beige writes "Gulfstream's Supersonic Business Jet work continues. Last fall, Gulfstream tested it's extendible spike sonic boom mitigating technology. Unfortunately, instead of calling it the Boom Boom, Gulfstream chose the name "Quiet Spike". The idea is patented. Gulfstream believes they can get the boom magnitude down to that of a "slamming car door". Whether or not that is low enough might be debatable, but it still is a big improvement."