The Beatles sing “Yesterday, all my troubles seemed so far away, now it looks as though they’re here to stay….”. Lennon and McCartney capture the essence of our relationship with time in just a few words. The singer was happy, things happen and he is no longer happy. From the point of view of the now, he looks back on the past and reflects on the unfortunate changes, and looks forward to a future which is less appealing than it was when, in the now that he was in then, he was happy.
In Lennon and McCartney’s words is encapsulated the feeling that the past is fixed and the future only partially knowable. Also it contains the idea that things change – the singer WAS happy, at some time in the past, and is no longer happy in the now.
Actually, since the singer is reflecting on his unfortunate position in the now, the change must have happened in the past. There was some past now when the change happened. Words begin to get a little tricky at this point.
From the point of view of the current now (tricky!) it is evident that change happens, but it is also apparent that barring time travel and the consequential paradoxes, the past is not changeable. How does that happen? How can it both be true that the past is fixed and that changes have happened in the past?
This issue is related to the issue of the now. Evidently every point in time is a now point. If you consider what you were thinking or doing 10 minutes ago, you will realise that you considered that point then to be the now, not the current now.
However, if you consider that the past is unchangeable, you could consider some future now and you will realise that from that future now, the future from the current now to the future now is the past from that future now and therefore unchangeable. So it appears that the future is also unchangeable. This leads logically to a strict determinism.
A certain change happens at some time or other, a particular now. It is possible, though unlikely in my opinion that mind, either of man or animal, may affect things after all. If that is so, then for consistency the change must propagate into the future and into the past.
If space is represented by one dimension for simplicity and time is represented by another dimension, then space-time can be represented by a sheet. A change would distort the sheet a little. It would be as if a single point on the sheet moved sideways pulling the sheet with it, and in doing so neighbouring points would be moved as well, including points on time axis before and after the point where the change happened.
However as I say, I don’t think that the mind can affect things in this way. After all the state of the mind, and hence the choices that the mind makes are predetermined, so no choice can actually change anything.
There’s a saying – “Today is the tomorrow you worried about yesterday”. This phrase also encapsulates one way that we think about time. It has a tinge of inevitably about it, as it implies that tomorrow always comes whether you like it or not. It depends on the situation as to whether or not this is a hopeful saying or a statement of inevitability.
However the main idea that this saying conveys is similar to the idea that the Beatles’ quote above – tomorrow always comes, from the moment one is born until one dies. Well, actually, tomorrow always comes, whether or not one is alive.
Both sayings have a sense of the now moving towards the future. One concept of the now is as a sort of “cursor” travelling over the time dimension from the past into the future, but I can’t see that this is a helpful analogy. Each and every instant is a now and appears to a person as the unique now when they are experiencing it.
Another problem is that a rate of flow of time (or the rate of movement of the cursor) is logically suspect. The time dimension is used to measure rates of change so to have a measure of a rate of movement in the time dimension requires a further time-like dimension to measure the rate in. It reminds me of the apocryphal scientists who commented that we all travel through time at one second per second.
Our view of time is the now, sandwiched between the behemoth of the past and the behemoth of the future. We rarely “live in the now”, but spend a lot of our time looking towards the future or reflecting on the past. Yesterday is the source of our plans and the future is the target of our plans and aspirations.
We view the past and see how things happen, then we use that knowledge to set our plans with the intent of increasing the possibility that things happen in ways that are beneficial to us. This is a form of inductive reasoning which, while it doesn’t always work, works reliably enough for us most of the time.
The past is a burden on us as we cannot change it. All our mistakes are set in the concrete of the past, as are all our successes for that matter. In the now we try to determine what happens in the future by using the lessons of the past. We want things to be better in the future, and we project all our hopes and fears on to it.
The now is a sliver of time between the monoliths of past and future, representing, if we believe in choice, a chance to improve the future for ourselves. If we are determinists, the now is an illusion that occurs in our brain that merely serves to separate the past from the future at that instant in time in our consciousness. It is not unique, like a cursor sweeping over the timeline, but is a timeless experience at every point in time.