Anything. It's said with regularity that that's exactly what's possible, but is it?
Is peace between every nation—and person—on earth doable? What're the odds that every belly goes to sleep quiet and satisfied sometime soon? Or that every mouth enjoys clean water to gulp? What about universal endorsement that humans have a hand in the warming of our planet?
The list of possibilities to list goes on.
If anything truly were possible, what would it look like? Would we know it if we saw it staring back at us in the mirror?