Flow of time in a block universe

Question

On asking how there could be a flow of time in a block universe one user said

"In the block universe concept there is no physical flow of time. The flow of time is a purely mental sensation that does not depict reality. This mental sensation occurs at the events on a human’s worldline where the human is conscious"

according to above statement a human is concious of events along his wordline say $(X_1,y_1,Z_1,t_1)$, $(X_2,y_2,Z_2,t_2)$, $(X_3,y_3,Z_3,t_3)$, ... $(X_n,y_n,Z_n,t_n)$ If this were true our brain at each such event is only conciousness of that event not the subsequent or prior event and there's nothing that is connecting them to form a sequentially ordered subjective experience from birth to death ( since there is no physical flow or motion of any kind ) and this would also mean that brain at an event say $(X_3,y_3,Z_3,t_3)$ has the same experience again and again forever since nothing is changing in a block universe and no physical flow of time as well.

How does all of this explain flow of time?

And even if all of it were true how could there be any sensations/conciousness in brain if everything is frozen in time?

Answer 1

If this were true our brain at each such event is only conciousness of that event not the subsequent or prior event and there's nothing that is connecting them to form a sequentially ordered subjective experience from birth to death [emphasis added]

This is not correct. While we do not have a full mechanical theory of consciousness there is nothing in a sequential ordering that is inconsistent with the block universe. This is also consistent with our standard formulations of the laws of physics.

Specifically, the laws of physics are written as differential equations, for example, the heat equation is: $$\frac{\partial u}{\partial t}=\frac{\partial^2 u}{\partial x}$$ This differential equation involves derivatives in both time and space, meaning that the value of $u$ at one point in time and space is connected to its value at other points in time and space. This differential equation is the connection referred to above.

Note, that we can either consider $u$ to be a multitude of one dimensional functions which are evolving over time or a single two dimensional function of both space and time. The math is identical, the experimental outcomes are identical, all that differs is the philosophical interpretation. Nothing physical required one interpretation or the other.

Similarly, although we do not have a mechanistic theory of consciousness, we would expect such a theory to be expressed as a differential equation. That would provide the necessary connection of our subjective experience. Solutions to that differential equation could then be interpreted either as a multitude of psychological states evolving over time or as a single higher dimensional function of time.

The block universe is consistent with our psychological experience of time. It is merely an arbitrary philosophical interpretation of the standard form of the equations describing physics.

Answer 2

The block universe concept might be compared to thinking about a movie from the point of view of one who has the entire movie on a film. Imagine the film laid out in a big stack, one frame on top of another. When a character in the film decides to go one way or another, the video frames show which way they actually decided to go. When a car in the film is zooming along a road in a sequence of frames, then in the next frames you can expect that the car will be shown further along that same road.

The question raised here about conscious experience relates to this as follows. The most natural assumption is that our conscious experience is a reflection of what our brains and bodies are doing. So if we imagine such a video film with frames showing the detail right down to the level of cells and molecules, then from one frame to the next the film shows the molecules going through their various interactions. Those very interactions are the physical support of the conscious experience of the people having the experiences. So the conscious experience is simply another way of referring to the molecular interactions: it is those same interactions but viewed from the inside, as it were, rather than the outside.

Let's use the term "the subject" to refer to a person having a conscious experience.

The above picture is consistent with the view that at each moment such a subject experiences just that moment and no other. But it does not imply that the subject experiences only that moment. It implies rather that at each moment they experience the experiences relevant to that moment.

I don't think this removes all the puzzles associated with our experience of time, and indeed I think we do not know enough yet to be able to sustain the claim that the universe can be captured in full by such a model. But it is a good working model to have in ones toolbox. Maybe it cannot undo all nuts and bolts, but it can be applied to a good many.