LIGO Pathfinder: The Freest Fall

A key component of a future gravitational wave observatory passed a series of tests with flying colors, while coming closer to experiencing true free fall than any other human-made object ever has.  At the heart of the experiment is a two-kilogram cube of a high-purity gold and platinum alloy that is currently sailing through space almost completely free of any force other than gravity.  The LISA Pathfinder test mass is made of high purity gold-platinum alloy. At current prices, the raw materi...