Sean Carroll: Causality and the Arrow of Time
Causality and the Arrow of Time exist, precisely because a mere Mathematical Identity cannot create a unique, corresponding Physical Identity
[link:www.quantamagazine.org/mass-and-angular-momentum-left-ambiguous-by-einstein-get-defined-20220713/#comment-5917089625]The "mathematically equivalent" and the "physically equivalent" are not equivalent, in the real, physical world[/link]
Rob McEachern