As a sort of therapy for the uncertainty and burden of living with the past and future in a present mind, I both pleasantly and presently present a cognitive method for addressing these with determinism. Determinism could be defined as: things can obey one universal law per universe and so can follow only one path, despite other possibilities within that universe…. as far as we can tell.
Cognizance of determinism forces mindfulness and reduces anxiety for other life paths via letting you see the current situation as the only situation you can have. We can only live in one instance of reality. So, when you are stuck thinking about the what-ifs or shoulda-coulda-wouldas, know that there is one path for you. This can help you stop worrying about other life paths you didn’t take or could take and just be in the life that is real to you here and now. Worry not for the non-real life you could have lived or should or might live. You just have this present bit and that is all.
The physics of it can be confusing with talk of parallel dimensions or alternate realities. All this is irrelevant from our perspective because past-change-talk and future-talk seeds no manifestation of multiple lives, just rumination of what is not here or now. No matter how physical theories are interpreted, the practical theory is we live one life with one outcome in one place and one time. There very well could be other dimensions or universes that invoke other possibilities into reality but we don’t see them or know anything about them; and we likely can’t and thus never will know them. As far as we can tell we manifest human experience in a single life in a single universe. The same would be if we manifested infinite times. If you can’t see it, then it might as well not exist.
To accept we are bound to the present and so assume we are bound to our reality comes a peace when anxiously thinking of how to change the past or change the future. Determinism tells us one physical reality is what we have despite probability of something else. No matter the probability or the foresight, one thing will occur 100% of the time and we only know it in the present. Sure, we can’t do anything but be what we’re determined to do, but we must interact with and engage life to follow the determined path. The critical factor is that we do not know the outcome of our present actions until a future present manifests in the now. We are bound to the now as the universe as we know it is bound to a deterministic present. Be grateful, the universe has made it easy for us; you wouldn’t want to be stuck chasing or ducking multiple lives in multiple times in multiple universes.
We can’t change the past and future as much as we can’t stop being present.
See Freewill to explore more about humans and determinism.