“Copenhagen.” The play is about the changing relationship of Bohr and Heisenberg before and during the Second World War, when they found themselves working for opposite sides. (Heisenberg was involved in the Nazi nuclear fission program—but the court of history has not rendered a verdict on whether he helped or hindered it.) One of the themes of the drama is that quantum uncertainty allows for simultaneous alternative realities—such as Bohr and Heisenberg being friends (because of their long-standing collaboration) and foes (because of the war) at the same time. At least in some productions a few members of the audience are seated in a “jury box” on stage—presumably to render a verdict on Heisenberg’s intentions. Thus, we found ourselves on the same panel, watching and judging the show. Tegmark appeared to enjoy seeing these alternative realities play out—like parallel realms in the multiverse of history.

Indeed, confined to our small enclave of space, we are all jurors, rendering a verdict on the unfolding cosmic drama. Like any jury, our varied prejudices and perspectives affect the outcome of our conclusions. Each of us decides what seems to be “crazy stuff” and what appears to be mainstream.

No measurement we make is wholly independent of our human experiences. Because we filter all information through our perceptions, in some sense we generate our own parallel universes—each a different facet of a multifarious prism. Hence, as Eddington pointed out, even if there is a true reality, it could well be lost in the mirror maze of subjectivity.


From the lowly vantage point of Earth, our instruments and intuitions have propelled us billions of light-years into the void and eons back in time. Questions unanswered for millennia have finally found credible answers. The ancient philosopher’s quest for the age of the

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