https://www.theguardian.com/science/202 ... -interview
This part was an absolute bombshell for me:
When the process of separation [of universes] happens, that’s the point when the cosmic microwave background (CMB) is created. So all the inflation fluctuations will leave scarring or dents as a result of this entanglement, and those will be imprinted on our [universe’s] CMB. That was something that we could calculate. So I calculated the strength of entanglement between the different branches and how quickly that entanglement gets washed out. That allowed me to find out how much denting or scarring that entanglement would leave on our sky as it was being created during inflation, and then fast-forward to the present day, to make predictions on how those very large-scale anomalies would look. One of the key predictions of cosmic inflation is that everything is sprinkled uniformly throughout the sky. But now the scarring coming from entanglement with the other universes is modifying or denting that uniformity, violating it at very mild scales. We predicted those, and they were seen by the Planck satellite [in 2013].
Wanna weigh in on this, Rommie?
The idea that prior entanglement could leave detectable traces is also new to me TBH, but then a) I don't know jack about quantum mechanics beyond the surface level layperson stuff, and b) the entanglement cases I have heard about are mostly with... photons, various fermions, maybe the odd whole atom or little cloud of Bose-Einstein condensate. Nothing like entire infant universes stuffed with > 10^53 kg of hot particles.
