Interference and Many Worlds

In the Everett multiverse theory, I understand that very similar universes are able to briefly interact before diverging, e.g. In the double slit experiment. Is it not the case though that two universes may continue to be identical following divergence, except for the one incident that caused the split? In that case, can't they continue to interact indefinitely ?
- Simon TWEDDLE (age 52)
Brisbane Australia

In the two-slit experiment, interference can continue until some large-scale objects (flashing lights, computers, brains,...) get involved in a way that makes them do different things depending on which slit the particle went through. That makes a quantum state that consists of two really different pieces, is different that there's in effect no way to get them back together to interfere. At that point, the Many Worlds interpretation say that two different worlds have emerged from what had been one. So, by definition, so long as there's some possibility of interference between different parts of the state, we say that those parts represent parts of the same world. 

You may wonder if this loss of interference is just a practical matter, making the distinction between worlds fuzzy. Susskind and Bousso (http://arxiv.org/pdf/1105.3796.pdf) argue that when cosmological horizons are considered there may be true irreversible loss of interference.

Mike W.

(published on 02/15/2016)