> because we can't create the yesterday in the lab either. We have access to memories of the past which are physical. Records in the rock strata of Earth's for

> because we can't create the yesterday in the lab either. We have access to memories of the past which are physical. Records in the rock strata of Earth's formation, neuronal connections in our brain of Grandma's barbecue and who was in attendance, red-shifted EM signals traveling since a few seconds after the big bang. The information of these processes and events is never lost. "The present is the key to the past" and such. Even every causal relation since t=0 could be worked back to arbitrary accuracy from t=n for a near-omnipotent civilization. One still following all laws of physics, just very advanced and capable. QM creates a novel situation imo where nothing, not even near-omnipotence, allows one to probe "pre-measurement". The very act of measuring causes something to occur. Scattering a photon or electron or proton with something is the smallest tool in quantum field theory, probably the most well studied near-fundamental theory in physics. There is no way in principle to ever probe pre-measurement because there is no disturbance-free way to observe. There is no sub-photon. There's nothing besides particles and fields to investigate with. There's no tool to build to improve things. The type of knowing in knowing the superposition of states pre-measumrent is not the same as knowing the past. We can arbitrarily improve tech to investigate the past to arbitrary degrees. The information of the past is out there, physically accessible to some kind of observer. In QM, there is no way to improve that lack of knowledge. It is forever inaccessible to any type of observer. If this still all exists for you, then what about the past? Why doesn't that exist? What notion of "exists" could you thread that denies the past's existence yet asserts the existence other inaccessibles? Surely there are kinds of existence in each of these ideas. (To be clear absolute size isn't the only motivator for QM, just one aspect of it).