I was recently invited on Brett Hall's podcast to talk about physics – specifically, the physics of time. In modern physics, various theories have the property that they do not require time as something fundamental. The main takeaway is that, in timeless views of physics, each moment exists together with all others in a kind of ‘block’. This block is timeless and doesn't change, but if we look at slices of the block, there appears to be time. If you want to hear the entire conversation, the recording is up on Brett’s channel (here’s a link).
In response to the podcast, some listeners have argued that time must be fundamental due to our personal experience of time passing, a phenomenon they believe cannot be explained unless time truly flows. For instance, one person replied to the podcast that,
’One cannot explain [the] experience of [the] passage of time in a static universe and any metaphysical claim that we live in a static universe is falsified by our experience of passage of time.’
The explanation for the experience of the flow of time is that we have memories of the past and anticipate a future. We have these memories throughout our entire existence, so even if all moments exist at once, there is an account for why a particular version of you living in a particular moment would think that time appears to 'flow'. It's similar to how physics tells us that the Earth moves, despite our experience suggesting it doesn't.
Another related criticism from the same listener is,
'There is an experience and I honestly cannot and have not ever been able to make sense of experience in a timeless view.'
Here, the listener specifically asks about how there can be conscious experience, not just the experience of the flow of time. We do not have a theory of consciousness, so the question, 'why is it that we experience anything at all?' currently has no answer, regardless of one's particular views on the physics of time.
This is why the criticism works equally well (that is, not at all) in response to other theories of time. For instance, for the sake of argument, assume that we live in a world in which only the present moment exists; this view of time is called 'presentism'. According to presentism, the world is a continuous series of moments, with each moment coming into existence and then immediately ceasing to exist as it is replaced by the next one. In this view, only the 'now' is real, as the past has already ceased to exist, and the future is yet to come into existence.
If only the present exists, how could we have experiences? How can a series of moments, each one infinitesimally short, leave enough room for conscious experience? We don't know, so clearly, presentism is no better than the timeless view on account of this.
One plausible solution is that we have 'experiences' (whatever those may be) in each infinitesimally short moment. I find this a plausible solution, partly because it works well with both presentism and the timeless view. That is, if we have experiences in each moment and if each moment in time exists together with all others in some larger, timeless structure, then there would still be experiences. In fact, there would be a lot of experiences in the timeless structure because each moment exists 'forever'. For instance, I remember having an ice cream last summer in Lugano. According to the timeless view of physics, last summer still exists and will always exist; it's just in the past. So, in some sense, I'll be 'forever' enjoying the ice cream last summer. This idea that the past will forever exist is charmingly captured by a song from one of my favourite TV shows (the full song can be found here):
Time is an illusion that helps things make sense
So we are always living in the present tense
It seems unforgiving when a good thing ends
But you and I will always be back then
You and I will always be back then
And all these sweet moments remain inaccessible. For now.
Thanks for the song 😊