- "There is only one universe. For lots of folks, this might seem like a no-brainer.
The "uni" in universe is supposed to mean "everything there is." Over the last few decades, however, multiverse cosmologies have gained acceptance via both inflationary Big Bang models and the "landscape" of string theory, which appears to predict 10500 possible universes. Unger and Smolin push back against these developments saying the proper field of study for cosmology is the one universe to which we have access. As Unger puts it: "We have reason to believe in the existence of only one universe at a time, the universe in which we find ourselves. Nothing science has discovered up to now justifies the belief that our universe is only one of many... The multiplication of universes in contemporary cosmology ... has been the outcome of an attempt to convert ... an explanatory failure into an explanatory success." - "Time is real. This might also fall into the "duh" category for people unfamiliar with the current frontiers of theoretical physics. But there were some good reasons why some physicists began thinking time might not be fundamental to reality. Instead, they began to explore how time might be emergent. That would mean time comes out of some deeper level of structure that exists entirely without anything like duration, past or future. But for Unger and Smolin, denying the reality of time allows physicists to skirt the nature of change on its deepest level."
- "Mathematics is selectively real. We physicists love our equations. They are so powerful that we often become convinced they are real in themselves. It is that way that we become platonists making mathematics a kind of skeleton on which the flesh of the world is hung. But for Unger and Smolin, this reification of mathematics can lead physicists into dangerous territory where mathematical "beauty" and "elegance" get substituted for real information about the real world. As they put it: "Our mathematical inventions offer us no shortcut to timeless truth... They never replace the work of scientific discovery and of imagination. The effectiveness of mathematics in natural science is reasonable because it is limited and relative."