The “block universe theory” is that the universe, all of space and time, is like one big unchangeable “block,” with time as one of its dimensions

that each moment is like an infinitely thin slice of the whole. infinitely wide in all dimensions of space, including that moment’s version of all that exists. and there are infinite slices, one for every moment in time

And that what we call “time passing” is combined of all those infinitesimal moments just existing together.

I did not learn the term “block universe theory” until a short while ago (relatively, in terms of my life).

Until then, I had not thought there was a word for it, because I had just assumed this was the completely obvious fact of what time was.

I’m pretty sure I had held that view ever since I first heard time described as a “dimension"… and/or ever since I first learned how animation works.

…time isn’t really a "dimension,” at least not in quite the same sense as spatial dimensions like length and width and height. But a comparison to those dimensions has always seemed to me like the only way visualizing time can make any sense at all.

My own visualization had been less like a “block,” and more like an animation, with moments being frames. And with time being the additional “dimension” that comes with being a movie (instead of a 2-D still picture with only width and height.)

When I first heard someone say that the “block universe theory” would imply that “time is an illusion,” this made no sense to me.

of course time isn’t an illusion. a universe with time is clearly, demonstrably different from a universe without time.

In a universe without time, nothing could ever change! Nothing could ever happen! Literally everything that happens takes time. If you had a portal that could take you into other universes, and you opened it into a universe that didn’t have time, you wouldn’t even be able to use it. Because… even just sticking your hand into the portal would take time. Even just looking through the portal to see that universe would require time, because light would have to travel within it. The portal to the timeless universe is just an impenetrable wall, and inside it is just one single unchanging moment. Of course that’s not the universe you live in!

and, if the block universe idea would imply time being an “illusion"… then what were people even imagining "real” time would be?

nothing I could try to imagine even made any logical sense.

someone tried to explain that the block universe portrayed time like a big unmoving tree, with each slice across the trunk yielding a slightly different inner picture, but the top and bottom of the tree still exist.

my response was… okay, but this is a spatial analogy trying to illustrate a temporal phenomenon. and, if you were talking about this spatial example the way you talk about time, you would be claiming that this view of a tree would imply that “height is an illusion.”

which wouldn’t make any sense either.

“but the example implies that the past and the future both exist simultaneously!” …no it doesn’t. that would be like saying “the tree’s branches and its roots both exist in the same place.”

different moments in time don’t exist “simultaneously,” because that’s the opposite of what “simultaneously” means.

the problem is …I think we don’t have words for what it seems like you’re trying to say.

our words, at least in English, are bound by time tenses. Only the present “exists.” The past doesn’t “exist,” it “existed.” the future doesn’t “exist,” it “will exist.” But that doesn’t seem to be what you’re saying either.

if you’re asking whether the future is “pre-determined” …what would that even mean.

That there’s only one future that’s gonna happen? (…well yeah, of course we’re only going to have one future. Or at least, one version of every future moment, though there are infinitely many of those. Sure– maybe, if there are other universes, different versions of our future selves will experience different things? but none of them will experience multiple universes at once. that’s just common knowledge.)

That it’s already certain which future that’ll be? That it’s already decided? (…what do you mean, certain? what do you mean, decided? are you asking if someone in the present or past decided what the future is going to be? or if someone can be certain what it’ll be? …no, I don’t think that’s what you’re asking, either.)

That we can’t affect the future? (what? of course we affect it! Everything we do is a cause for countless effects on the future. Even visualizing time like the arrangement of frames in an animation, “cause and effect” means the absolutely obvious fact that every frame contains details that relate to details in other frames in a specific way, following specific rules.)

(for example. if earlier frames show animated characters getting or making new things–possessions, physical conditions, circumstances, memories, differences in personality or appearance– then later frames will show them having those things. Until such time as they’re shown losing them, and not having them anymore from then on. And yes, in real life, the same is true for the connection of every moment to its past and future. Of course everything we do fits into that same framework.)

That we can’t “change the future”? (i.e. set it on a course other than its “predetermined destiny”?) …well, that seems like a question totally irrelevant to anything.

To even know whether we “changed” the future, we’d have to know both how it turns out, AND how it “was originally supposed to” turn out. And having that knowledge is completely impossible… and also so abstract I can’t imagine why people would ever CARE about that distinction.

(we care about whether an event was good or bad for us, of course! but… why care specifically about how it relates to a particular alternate version of the event that didn’t happen. Why.)

I guess this is connected to the idea of “free will.”

the concern many people seem to have over whether we’ve got “control” over what we do to ourselves, and each other, and our world, and our future.

and maybe it’s related to the other argument about whether this “free will” is “an illusion.”

…which I find silly in a similar, but also different, way to how I find it silly to argue about time being an illusion.

in the case of “free will,” I find the argument silly because 1. nobody in the argument can even agree on what they mean by free will, and 2. the argument always just seems to be about whether people should be punished or blamed for doing bad things.

Which can be a useful question, if it’s about the effectiveness of punishment and blame as societal decisions!

But not really useful in connection to a cosmological discussion of time and the phenomenon of cause and effect.

anyway. I have always thought it was obvious that “people” are combinations of moments over time, countless past selves at countless levels of the past, countless future selves at countless levels of the future.

and the “present” self isn’t really a thing. the present moment contains zero time; any experience that can take place “in the present” also includes part of the past and future.

the idea of “now” is like the spatial idea of “here.” And “here” is also a zero-dimensional exact location, and pretty much all of your self exists around that point, not in it.

and likewise, all “past selves” and “future selves” are also combinations of moments

and they aren’t separated from each other by any clear border or anything. your whole life is a series of moments. there are themes that usually persist throughout, but there isn’t one “self” that “travels” through all that time

anyway, if you ask me about people’s control over their choices, I will approach the question the way I approach any question about cause and effect.

Why do you make a choice?
Because your earlier self wanted to.

Is it possible to make a choice to do something you don’t want to do?
No. Or at least, it’s only possible to do that as a means toward something you do want.

(do a tiresome household chore? …because having it done is better than not.)
(do a job because you’ll be fired otherwise? …because you want to keep your job.)
(do a task because someone’s threatening you at gunpoint? …because you want to live.)
(give your life to save someone else’s life? …because you want that person to live.)
(do something completely pointless that gains you nothing, just to prove you can? …because you want to prove it.)
(do something you 100% don’t want to do because you totally can’t control it, like fall on your face because someone tripped you? …that isn’t a choice.)

your choices always follow the thing that your self in that moment considered preferable to the alternatives. That is the definition of making a choice.

there is, of course, a spectrum of how much control you have over an action, and how much conscious thought you gave it at the time. The less control and the less thought, the less it can be considered a “choice.”

But everything that was a definite choice was done because you had a reason to– and reasons come from preferences at the time.

Might not be the same thing that your current self, or your future self, or your past self at other times would have preferred. Might not be something that’s good for any version of you, or good for any version of anyone.

But it has to follow the rule that you did it for a reason based on preferring that choice over others. Again, that’s the definition of a choice.

And the next step back in the cause-and-effect is “why did your previous self have that preference?”

…which will always ultimately lead to causes outside the control of any version of you.

there’s no point at which any version of you can choose to set that chain of cause-and-effect onto a course that doesn’t follow those rules.

so, is that free will?

Sure! in the sense that “people do what they want.” That’s basically the whole essence of what I’ve just described.

Which is the most free will you can possibly hope for, really! It’s as free as you could ever want to be! Why would you wish for an ability to do things you have no reason to do?

It doesn’t mean you have to just give up and stop trying to do anything because you have no control over what you’ll do. That’s practically the opposite of the point!

“trying to do things,” and “succeeding in doing things,” are part of your nature! You’re gonna keep making choices based on what you feel you have a reason to do in the moment. And your choices and actions are going to keep having effects on the future. Even if your action is to choose inaction! It will succeed in accomplishing something, no matter what!

You don’t know what the “something” will be. But that’s no reason to try to stop doing the things you want to do.

…still, when people hear an analysis like this, sometimes they don’t want to accept it.

and often, that’s because they feel like it would mean they weren’t justified in being angry about what other people have done.

because it would mean those other people also had no ability to do things they didn’t want to… and those other people also had no ability to choose their wants… so they could never have had a chance to do anything different.

and (the way some people see it) this would mean you don’t get to be mad at others for what they’ve done. or punish others for what they’ve done.

and this feels intolerable, so they can’t bring themselves to accept this analysis.

…This, I think, is a symptom of being raised in a society that treats “punitive justice” and “revenge” and “deserving” as if they were self-evident facts.

And treats emotions as something you have to earn a right to.

when really, the question of whether you’re “justified in feeling” anger at someone who hurt you… is as ridiculous as the question of whether you’re “justified” in feeling physical pain from the same injury.

Feelings, physical or emotional, are simply things you feel, they don’t need justification.

And, of course, acting on your feelings about another person will have consequences that you’ll probably want to plan for before you act. But that’s not as closely tied to “why did someone do something” as people tend to think it is.

for instance, if someone hurt you, and you feel like cutting them out of your life entirely, the only relevant points are things like:
Do you think this person would be likely to hurt you again, if you stay in contact with them?
Do you think you’d ever be able to feel comfortable or happy around them again?
Do you think it would improve your life, and/or anyone else’s, to live the rest of it without this person?

those things don’t have to be connected to existential questions of “free will” at all.

and the same is true for similar questions about how justice and law enforcement should be carried out.

really, the same is true for all decisions about whatever you’re gonna do in life.

So, I guess my view of how we should act in this world is exactly the same, irrelevant to whether Time and the Universe are the way I visualize it, or the way other people visualize it.

I… just can’t quite model in my head what other people ARE visualizing.

…But that’s okay.