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In this image, the light trail left by traffic illustrates an idea central to the growing block universe theory of time, that the past, present, and future coexist. |
By Keith Tidman
The block universe is already filled with every event that ever happens. It is where what are traditionally dubbed the past, present, and future exist simultaneously, not as classically flowing linearly from one to the other. As such, these three distinct aspects to time, which by definition exclude the notion of tense, are equally real. None is in any way advantaged over the others.
The orthodox model of a ‘block universe’ describes a four-dimensional universe, resembling a cube, which merges the three dimensions of space and one of time, along the lines that Albert Einstein theorised in his special relativity.
Might this tell us something about the possibility of free will in such a universe? Before we try to answer, let’s explore more particulars about the block universe itself.
If observed from outside, the block would appear to hold all of space and time. The spacetime coordinates of someone’s birth and death — and every occurrence bracketed in between — accordingly exist concurrently somewhere within the block. The occurrences are inalterably and forever in the block. This portrayal of foreverness is sometimes referred to as ‘eternalism’, defined as a complete history of all possible events.
Conventionally, the block is considered static. But maybe it’s not. What if, for example, what we ordinarily call ‘time’ is better called change? After all, the second law of thermodynamics tells us that the state of entropy of the entire universe — meaning the presence of disorder — will always result in a net increase. It never decreases. Until, that is, the universe ultimately ends. Demonstrating how change, as in the case of entropy, moves inexorably in one direction. The inevitability of such change has a special place for humankind, as reality transforms.
Entropy is thus consummate change, on a cosmic scale, which is how the illusion of something we call ‘the arrow of time’ manifests itself in our conscious minds. As such, change, not time, is what is truly fundamental in nature. Change defines our world. Which, in turn, means that what the block universe comprises is necessarily dynamical and fluid, rather than frozen and still. By extension, the block universe challenges the concept of eternalism.
This also means that cause and effect exist (as do correlation and effect) as fundamental features of a universe in which ‘becoming’, in the form of change, is rooted. Despite past, present, and future coexisting within the block universe, causes still necessarily precede and can never follow the effects of what appears as relentless change. Such change serves, in place of illusory time, as one axis matched up with three-dimensional space. The traditional picture of the block universe comprising nondynamical events would contradict the role of cause in making things happen.
So, let’s return to the issue of free will within the block universe.
First off, the block universe has typically been described as deterministic. That is, if every event within the universe happens simultaneously according to the precise space and time coordinates the model calls for, then everything has been inescapably preordained, or predetermined. It all just is. Free will in such a situation becomes every bit as much an illusion as time.
But there’s a caveat pushing back against that last point. In the absence of freewill, humans would resemble automatons. We would be contraption-like assemblages of parts that move but lack agency, and would be devoid of meaningful identity and true humanity. We, and events, could be seen as two-dimensional set pieces on a stage, deterministically scripted. With no stage direction or audience — and worse, no meaning. Some might proclaim that our sense of autonomy is yet another illusion, along with time. But I believe, given our species’ active role within this dynamical cosmos, that reality is otherwise.
Further, determinism would take us off the hook of accountability and consequences. Fate, bubbling up from the capriciousness of nature’s supposed mechanistic forces, would situate us in a world stripped of responsibility. A world in which our lives are pointlessly set to automatic. Where the distinction between good and evil becomes fuzzy. In this world, ethical norms are arbitrary and fickle — a mere stage prop, giving the appearance of consequences to actions.
And yet, the blueprint above replacing the concept of time with that of change puts free will back into play, allowing a universe in which our conscious minds freely make decisions and behave accordingly. Or, at least, seemingly so. In particular, for there to be events at the space-change coordinates of the block universe, there must be something capable of driving (causing) change. The events aren’t simply fated. That ‘something’ can only be choice associated with truly libertarian free will.
There’s one other aspect to free will that should be mentioned. Given that motion within the three-dimensional space of the block universe can occur, not only the what but also the where of events can be changed. Again, agency is required to freely choose. It’s like shuffling cards: the cards remain the same, but their ‘coordinates’ (location) change.
In refutation of determinism, the nature of change as described above allows that what decisions we make and actions we take within the block universe are expressions of libertarian free will. Our choices become new threads woven through the block universe’s fabric — threads that prove dissoluble, however, through the ceaselessness of change.
