They figured out how to cloak objects from detection... if they're underwater....
https://phys.org/new...ek-anymore.html
The gist: they have materials that can deflect sound waves around the object without distorting the waves... so the sonar guy thinks nothing's there...
If the Navy's not paying for this work already, they will be soon... I think it means the life expectancy of aircraft carriers in future war time just went way down...
