The problem with the past is that while the events occurred, most of the information is rapidly lost and part of the confusion is assuming there to be some objective course of events, when everything, including and especially memory, is extremely fragmentary. The “past” might not change, but our ability to understand and perceive it is constantly rapidly changing.
The very fact our remembering it even changes it, as this evidence is arranged and stored. The mound of sand is constantly shifting and this is what creates change and thus time.
Which goes to the point that only the present is physically real.
The idea of time as a dimension means that the events are more real than the present. Physics likes this because the events are what is measured, as duration, yet it is in the context of the present that they are measured. It’s not really that we travel along this dimension of time, like we might travel along a linear dimension of space, but that the events are being created and destroyed by the process. Going future to past.
The reason time is asymmetric is because what is actually measured, action, is inertial. The earth only turns one direction. The assumption of it being symmetric is based on this dimensional modeling, that a unit of time is like a unit of space, where it doesn’t matter if we go left/right, or right/left, the unit is the same. So assuming time as a dimension, rather than a process, then the unit is the same, whether you measure event A to event B, or event B, to event A. Entropy, the relative order of the system is not what is directly measured as time. When we measure time, it is a specific, predictable action and that presumes inertia.
Consider the argument for the dimensionality of time tries to dismiss the simultaneity of the present by observing that different events will be observed in different order from different locations, as though this means all events actually exist out on the time dimension. Yet this is no more consequential than seeing the moon as it was a moment ago, simultaneous with seeing stars as they were years ago. It is the energy that is conserved, not the information/form! Remember the event of that star radiating the energy you are now seeing cannot still exist, because the energy is no longer there, if it’s entering your eye. Conservation of energy is incompatible with time as a literal dimension.
The present is not so much a dimensionless point between past and future, as it is the configuration of the energy. Though as much of this energy is light, it seems pretty dimensionless.
Another point made is that different clocks will run at different rates in different gravitational fields, or under acceleration. Yet clocks can run at different rates simply because they are separate actions. Think metabolism, or frequencies. That different situations will affect the rate of change is not that strange. People might assume there is some universal, Newtonian time, which Einstein presumably disproved, but there isn’t. Every cell in your body is its own clock. Though they do tend to be synchronized, as a function of you being a single organism. Just as society requires everyone to use the same measures, play by the same rules, speak the same language, etc, as a function of being a community. It’s a further example of our mistaking our experiences as universal, rather than an effect of our experience.
Consider that epicycles were brilliant math, as a modeling of our view of the cosmos, but lousy physics, because the assumption that we are at the center is wrong. It took awhile to work out an effective heliocentric model, because we don’t have the benefit of being able to look out from the point of view of the sun. We are the center of our point of view, both as a species and as individuals.
Similarly Spacetime models our narrative experience as foundational, not as an effect of our sequential process of perception. It is very difficult to see everything around us happening at once, because our minds don’t work that way.
