The most quiescent environment ever engineered by humans exists some 1.5 million kilometers from Earth, scientists announced Tuesday.
There, shielded inside a European Space Agency spacecraft called LISA Pathfinder, two 4.6-centimeter gold-platinum cubes have reached an almost-perfect state of stillness, subject to scarcely more than the pure force of gravity as they orbit around the sun. All other influences that could cause the cubes to move—jostling molecules, impinging cosmic rays and wavering electromagnetic fields—only impart a collective force roughly equivalent to the weight of a single virus held in your hand. The feat, detailed in Physical Review Letters, is a major milestone in the quest to study the cosmic ripples called gravitational waves, and it paves the way for future gravitational-wave observatories in deep space.
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