A superselection rule is a special limitation on what is observable in the quantum world. For example, we can never seem to observe interference from the relative phases between a…
Read moreWhat is a superselection rule?
Philosophy and Physics in the Kadison-Singer Conjecture
A promising proof of the so-called Kadison-Singer conjecture was announced yesterday. Mathematicians are excited, because this conjecture is equivalent to a remarkable number of open problems in other fields. And…
Read moreWriting a book on time reversal
So, I’m writing a book on the foundations of time reversal. I’ve decided to bring back the Soul Physics blog to talk about the book as it’s being written, and…
Read moreBeyond the CPT theorem
Virtually all known laws of physics are invariant under the CPT transformation — that is, the combined operations of Charge conjugation (C), Parity or “mirror flipping” (P), and Time reversal…
Read moreFour 1975 Lectures by Paul Dirac
Slobodan Perovic (via Chris Joas) pointed this gem out to me. Four wonderful lectures given by Paul Dirac in 1975, on various topics in the foundations of quantum theory and…
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