That means that an object under the stack - in the team's experiments, a block of wood about 10cm long - would not "hear" the sound, and any attempts to locate the object using sound waves would not find it.

BBC: Acoustic 'cloaking device' shields objects from sound

The Near Earth Object (NEO) database is working to do that, but it is very difficult to locate all of the objects either closer to the sun or behind it.

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