Is there a way to concisely define the modular automorphism group of a von Neumann algebra $M$ for a "lay" person?
I have little more than a vague fuzzy overview of Tomita Takesaki Theory and I'm unsure if it would be wise in my situation to get buried too deeply in it. But any mention of the modular automorphism group which I encounter tends to refer me to a rather intimidating multi-volume series or more advanced (at least to me) research level papers.
