Links for Episode 30
Physics Courses
Quantum Mechanics for Everyone from EdX. (In the episode, I said this was from Coursera, EdX’s competitor. Sorry!)
Sean Carroll’s Biggest Ideas in the Universe
For very serious learners, Hoffman recommended Nima Arkani-Hamed’s graduate class from Harvard
Hoffman’s argument as presented in recent papers
Objects of Consciousness (Hoffman et al. 2014)
Fusions of Consciousness (Hoffman et al. 2023a)
Award-winning Project Proposal (Hoffman et al. 2023b)
Is spacetime “doomed”?
Nima-Arkani Hamed thinks so
David Gross talked about this after winning the Nobel prize in 2004. However, I cannot find the exact citation. It is common to find these words online:
“Everyone in string theory is convinced…that spacetime is doomed. But we don’t know what it’s replaced by. We have an enormous amount of evidence that space is doomed. We even have examples, mathematically well-defined examples, where space is an emergent concept…. But in my opinion the tough problem that has not yet been faced up to at all is, “How do we imagine a dynamical theory of physics in which time is emergent?” …All the examples we have do not have an emergent time. They have emergent space but not time. It is very hard for me to imagine a formulation of physics without time as a primary concept because physics is typically thought of as predicting the future given the past. We have unitary time evolution. How could we have a theory of physics where we start with something in which time is never mentioned?”
Not everyone agrees, though.
Needless to say, one can also say that spacetime is doomed, but take a very different direction than Hoffman and colleagues. According to Hoffman, this is what Sean Carroll does.