The idea that the cosmos constantly splits into parallel universes ~ in which every conceivable outcome of every event happens ~ has been unified with the idea that our universe is part of a larger multiverse. While solving a bizarre but fundamental problem in cosmology, the concept and has set physics circles buzzing with both excitement and bewilderment.
The problem is the observability of our universe. While most of us simply take it for granted that we should be able to observe our universe, it is a different story for cosmologists. When they apply quantum mechanics - which successfully describes the behavior of very small objects like atoms - to the entire cosmos, the equations imply that it must exist in many different states simultaneously, a phenomenon called a superposition. Yet that is clearly not what we observe.
Cosmologists reconcile this seeming contradiction by assuming that the superposition eventually "collapses" to a single state. But they tend to ignore the problem of how or why such a collapse might occur, says cosmologist Raphael Bousso at the University of California, Berkeley. "We've no right to assume that it collapses. We've been lying to ourselves about this," he says.
In an attempt to find a more satisfying way to explain the universe's observability, Bousso, together with Leonard Susskind at Stanford University in California, turned to the work of physicists who have puzzled over the same problem but on a much smaller scale: why tiny objects such as electrons and photons exist in a superposition of states but larger objects like footballs and planets apparently do not.
Click here for the complete article.