End Gadget: There are numerous efforts underway to clean the world's oceans, but The Ocean Cleanup is testing what may be both the simplest and the most ambitious. It just launched a 328 foot-long prototype floating barrier that will collect trash floating in the North Sea. If it can survive the rough conditions of those waters, the plan is to deploy a 62 mile-long (!) barrier in the Pacific Ocean and reduce the size of the notorious Great Pacific Garbage Patch -- the hope is to halve the size of the trash field...