Is our universe a bubble in a multiverse? Test developed.

Upper left models a bump between bubbles and the
other three quadrants show how the bump signature might scatter
over billions of years, leaving traces we can find.

The theory that our universe is contained inside a bubble, and that multiple alternative universes exist inside their own bubbles -- making up the 'multiverse' -- is, for the first time, being tested by physicists.

Bubble interactions

The idea is that if there's a foam of universe bubbles out there, they should leave marks on each other when they bump.   Dr. Pieris' team at University College London are tackling the math.    The story gives me a tingle down my leg but you'll have to talk to experts to get it explained.