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Scientists Invent a Tractor Beam Made of Sound

Philip Marston
Philip Marston

Scientists have long been able to levitate small objects, like drops of water or plastic pellets, using only the power of sound. By sandwiching an object between two sets of speakers—or a speaker and a reflector—you can send precise, energetic blasts of ultrasonic noise to trap objects midair. But today, a fascinating new breakthrough can now accomplish this odd feat of levitation with a single array of speakers on just one side. It’s like using sonic tongs with just one side instead of two. » More …

The Puzzle of Planetary Protection

Dirk Schulze-Makuch
Dirk Schulze-Makuch

In the paper, called The Overprotection of Mars, co-authors Alberto G. Fairén of the Department of Astronomy, Cornell University and Dirk Schulze-Makuch of the School of the Environment, Washington State University argue that the level of planetary protection needed to go to ‘sensitive areas’ would be prohibitively expensive to achieve. » More …