The longer you live with the block universe in mind, the more you get used to it. So what follows below is only half tongue-in-cheek. It’s a set of design options you can apply to create the block universe you feel most comfy with, or that best fits the audience you’re talking to. Or that matches some obscure data-points of yours.
The Soft Block
First of all you will have to explain the odd status of past and future in a block universe. To some people you will quite cautiously speak about how the past in some way still exists, and how the future somehow is already there. The rationale may include dropping the name of Einstein, pointing out the time-independency of the laws of physics, and evoking the deterministic nature of the universe.
Listen to how Caltech physicist Sean Carroll does it:
The prime stratagem is to embrace a strong (capital D) Determinism. Causality can have no wiggle room here, which guarantees for the computability of all past and future states of the universe.
There remains, however, an ontological uncertainty regarding the existential status of those past and future states of the universe. Which is why proponents of this derivation usually shy away from making definite statements about them. Past and future are there somehow.
While the deterministic part certainly feels a bit tight, the blurry ontological outlook is a true relief for starters and the faint of heart. We can call this gentle approach to the block universe the soft version, and its subject the Soft Block. It’s a bit like a block universe light. Speak of the Laplace Block, if you want to go with it.
Well, the obvious downside of this module is its vulnerability to the following questions:
How can a physically pre-determined universe, a universe that is physically settled in advance, also be a socially and mentally pre-determined universe? How can something fickle as thought or social interaction be written in stone long before it ever happens? Isn’t that the most gross reductionism imaginable?
And how, and where, does the universe re-calculate its past and pre-calculate its future? Is there a cosmic server-farm somewhere?
For the moment the most promising response is to hint at some cutting-edge work that suggests that the universe and the brain are actually quantum computers. This kinda solves the issues. Somehow.
The Hard Block
True Blockers (Blokkers, even) don’t shy away from answering the ontological question. There is no need to re-calculate the past, and no need to pre-calculate the future. Gosh. You can simply go there!
When technology is finally up to the task, that is. But that’s the kind of real we are talking here. Everything at every point in time is manifest and happening right now. Your personal Now does not cut spacetime into an objective past and an objective future. What belongs to the future for you is part of the Now for somebody else, the same way a region of your past will be in the Now for another observer.
There is no privileged Now, as they like to say. And since no one’s Now makes the objective cut between past and future, there simply is no such thing as an objective past, present and future. This view is sometimes called ‘Eternalism.’ Some people speak of the ‘Tenseless Model of Time.’ The rationale behind it has to do with the way we cut bread, I believe.
I refer you to Brian Green & Friends in what’s probably the briefest introduction to the block universe ever:
The tangible reality of the future and the past certainly is a strong claim, and it takes a bold heart to really give it a try. Thus we can call this the strong version of the block universe, and its subject the Hard Block. It surely is the block universe proper. And Minkowski Block is a fitting name, for Minkowski’s geometric representation of special relativity got the whole thing going.
However, this module will raise one very simple question:
Will there ever be more than argumentative or diagrammatic “proof” that cosmic now-slices equate to ontological realities?
To extrapolate from something that is well-proven (special relativity, in this case) is no proof in and of itself. And arguments or diagrams are just epistemic crutches.
But here is the thing: While the Minkowski Block is not exactly science, it is at least good science fiction. Good science fiction in the sense of hard science fiction. It’s a reasonable extension beyond hard science. And in the same way we want serious science fiction to give us a look into what might be coming, we should be open to the picture the block universe draws of reality. It might well be that it enables us to see things coming we otherwise would be missing. It might indeed enable us to look into the future.
Okay. You will have to look whether the Minkowski Block allows you to make testable predictions that are suited to falsify or consolidate its claims. Since you like it scientific.
The Many Worlds Block
The next question you really want to have settled is how the deterministic nature of the block universe goes along with the bizarre behavior the quantum realm exhibits.
The most popular answer to this is the many worlds interpretation. And, contrary to other multiverse theories, the many worlds interpretation describes a perfectly deterministic block universe.
It is a block universe in which every possibility that occurs in the quantum world splits off into an own world-line. Every possibility is an actuality right away. It spreads into an own world with a truly deterministic one hundred percent certainty. No probabilities anywhere.
And the quantum realm is not simply a micro-world underneath our macro-world. No, everything is quantum without exception. It’s no longer a macro-world observer looking at a micro-world experiment. It’s all entangled quantum systems.
Here’s the pitch for the many worlds interpretation:
It is not by accident that this is the same Sean Carroll as with the Laplace Block. Space-time* has no foundation on the quantum level; there is no variable for space in the Schrödinger equation. So if you are going to draw a deterministic universe exclusively by means of quantum mechanics you cannot reason with special relativity to explain its determinism. It’s deterministic because it’s a Laplace Block based on the many worlds interpretation of quantum mechanics. Every possibility is true. Every world line exists.
Somehow. In a superposition. As a part of the wave-function of the universe.
MIT physicist Max Tegmark classifies the many worlds interpretation of quantum mechanics as a Level 3 Multiverse**. Nonetheless it would be misleading to call the subject of this module a multiverse block. It is a Many Worlds Block, and we can call it by the name Everett Block, for it was Hugh Everett who came up with the many worlds interpretation back in the 1950s.
The most obvious objection you will encounter with this module is:
If every minute possibility splits off into another world you will end up with way to many worlds. The amount of worlds would be insane! Is the universe even big enough to house such a mess?
I’ve seen this answered in two ways. The first answer points out that Hilbert space has plenty of room to offer, and the second insists that there are no new worlds created. All the possibilities and their world lines already exist within the wave-function of the universe. The universe just gets more differentiated with every division.
Don’t know what a Hilbert space is? Me neither. Go look it up!
The Two-Time Block
Many worlds is such a sweet and simple solution. But what is the alternative to branching off into innumerable independent worlds? How to get back from this to something that is closer to our everyday experience? To something that happens solely in our beloved, single universe?
Yeah, that’s the question of questions of quantum mechanics. What do we have to add to the nicely deterministic Schrödinger equation to avoid its literal, i.e. the many worlds interpretation? How do we trim away this excess of branches and convince ourselves that they were dead ends anyway?
The problem is that every quantum interaction, including every measurement, yields a plurality of possible outcomes. You’ve certainly heard of their superposition, or them somehow inhabiting the wave-function. But a plurality is not what’s being measured, or rather, it’s not what’s showing up in the measurement. What shows up, mediated by a whole epistemological snake pit of its own, is a single distinct outcome. That’s the famous collapse of the wave-function.
Now, what’s the problem with that? The problem is that, empirically, the singled out outcome comes out within a certain range of probability. That means it might as well have not come out; even if the probability of that was very low. It’s nonetheless given. And that breaks the classical deterministic view of the universe.
“God doesn’t play dice!” Remember? That’s the way to convince your physicist colleagues. So, how do we fix this?
Thank God, we are constructing a block universe here. This means that the initial conditions of an interaction are no longer the sole contender for all the heavy lifting in the determinism department. Since the whole history is already played out in a block universe, why not assume that everything ahead of us is not just passively hanging around there?
What if the outcome of a measurement is a product of two interacting wave-functions, one coming from the past, and the other coming from the future?
Only possibilities that support the future outcomes would survive; all the others were cancelled out; say by destructive interference, if you like your wave-functions literal. Problem solved:
Remember, in a block universe the future is already there. So it’s perfectly possible that events, at least on the quantum level, are determined by two time-arrows; one from the past and one from the future.
Note also that this solution for quantum madness is not taken out of thin mathematical air. It’s based on real experimental findings that are undisputed, even if their interpretation, of course, is not. A very, very much abridged extra super-short version goes like this:
If you shoot particles through an arrangement of different measurement-pathways in order to collect data about different quantum properties, and then just focus on one specific property and ignore the rest, the signal for this exact property will turn out to have been significantly amplified.
The well documented miracle here is, that the final state of the measurement conditions the midway states that lead to it. The intentional manipulation of this final state is called post-selection. You basically focus on a special subset of the collected outcome and throw the rest away.
Turns out, this miracle seems to be really useful for quantum computing. It’s not just an experimental finding, but it has actual practical applications. So much so, that its serious interpretation is given a comfortable backseat for now. –It works! So who cares?
Well, Yakir Aharonov does, and he takes what is given straight up at face-value. Why sneaking around it? Special Relativity says we live in a block universe; so be a man about it. The future influences the past, as the past influences the future. Simple as that.
His Two-Time Interpretation of Quantum Physics further extrapolates on the post-selection part by postulating a final boundary condition for the whole universe, similar to the event horizon of black holes. (And to the wave-function of the universe in the many worlds interpretation.) This Two-Time Interpretation is why we term the subject of this module the Two-Time Block.
And since Aharonov introduced the physics community to the weak measurements* that you need to perform the said miracle, and the whole “weak measurements plus post-selection” thing is pretty much his baby, it’s only fair to call this take on the block universe the Aharonov Block.
Well, the most obvious problem then:
Isn’t this an unnecessarily overblown interpretation of one single type of experiment? – It is not even clear how to come to terms with the experiment, so why straight away shooting for the whole universe?
The only answer I can think of is: Why not? It might as well turn out to be the right shot.
The Dark Block
To be confronted with serious hints that we might live in a universe that is pre-determined from start to finish can be quite the shock. Especially in our day and age, when everyone is told that true living is to conquer your life. Overcome the obstacles! Strive! Achieve! Look how this guy did it! Look how she made it!
We revere agency. And along comes the block universe and cancels agency: It’s all predetermined, stupid! You are an illusion! Free will is an illusion! You’re nil. Deal with it.
Especially for the smart and capable people that must come like a stroke. Out of nothing and you’re disabled. A mere shadow of yourself. Someone who does no longer play a role in one’s life. That’s grim.
The father of the Bell Theorem, John Bell, certainly a smart and capable man, once admitted that he was unable to seriously look into a certain solution for the quarrel about quantum entanglement versus the speed of light. That’s the very problem his famous theorem is all about, but he simply couldn’t stand that solution. Because it does entertain the notion of retro-causation, of influences going backwards in time, implying a pre-determined, a block universe.
Here’s Cambridge professor Huw Price presenting Bell’s admission:
So if you want to bring someone bright down, convince her that we live in a block universe. She will fall prey to fatalism and probably end up as a drunkard. Congratulations!
If you, on the other hand, have someone who is already down, you might actually cheer him up by explaining that it is not his fault. It’s the */%& block universe that is shit, and he could never have done something about it anyway. Cheers!
Seems in both cases we end up with a drinking habit. But while in the first case it is nihilistic self-medication, in the second it’s clearly happy drinking!
In an absolutely determined block that is indeed pre-determined everything behaves like on rails, or like a script that is played out one scene after another. This is the most dull and boring version of the block universe, and probably the one we usually meet first.
The only thing you can do here is to give in to what is unfolding, to what is the plan. To be the puppet you are supposed to be.
The thing is, the very idea of giving in suggests that there is a paradoxical freedom in this totalitarian block:
If everything were on fixed rails there would be no need to give in. The need to surrender occurs only when there’s freedom to misbehave. When you can have a position to the block, instead of simply having a position in the block.
The same applies to the idea that the block universe cannot allow certain things to happen and therefore will prevent them. There would be no need to prevent something if there were no room to do things that are to be prevented.
But we should not talk this way, because we are facing a totalitarian block that probably kills aberrations. An Archon’s block where the Dark Overlords of Time erase all resistance.
I’d rather not give someone’s name to this block. A Dark Block it certainly is.
The Smart Block
When I tried to explain the block universe to my ten year old lately, his mother came in, grumbling: “If everything is pre-destined anyway, then why bother? Next subject, please!”
She’s kind of right about this. In some way it doesn’t matter whether we live in a block universe, or not.
For one thing, the block universe is a mere theoretical conclusion, not an empirical finding. And beyond its value as an intellectual reassurance that time-bending phenomena are within the range of rational integrity, it offers no practical guidance of any kind. It doesn’t add anything to the insight that you could take your own precognitive fine-tuning a bit more seriously, if that is your jam.
And it doesn’t set any ethical standards or rules about what to do or what to refrain from. Even more: The block universe doesn’t set any limits to what you can do in the world!
Think about it: – The only thing it does is to state that it already knew before. And it seems to be right about that. But, why bother?
You’re just a bit ahead of yourself.
If you sport a certain mental big-picture capacity, the block universe is a serious mindfuck. But you will realize very quickly that life goes on as usual, no time police anywhere: The block is all in your head!
That’s good news, isn’t it? You can be as revolutionary, or surprising, or original as it gets! Or as easy going, or as low key, as you want. Free your mind! A block universe worth its salt will have no problem at all with your free will. And it will have known before, no matter what.
A perfect mystery.
But here comes the dark voice invading the bliss:
It is exactly the future part of determination that makes actions look unique and surprising. Since we don’t know the future, the flattering impression of creative genius occurs; an appearance of inspired individuality that shapes the future, instead of being shaped by it.
But what looks like an open playground for individual genius is in fact already criss-crossed by future vectors. What gives the impression of ‘Agency’ and ‘Free Will’ and ‘Creative License’ is really our inability to remember the future, and thus to conceive of the force of retro-causation.
If you want to entertain the Smart Block you better have a serious counter move up your sleeve now. Maybe you want to play a mind-over-matter card. Or defeat space-time with an imaginal mind-matter Joker. Maybe you have to do a Socrates impression, subtly accusing your opponent of hubris by demonstrating your epistemological humbleness: I know that I don’t know what I don’t know.
We are calling the subject of this module a Smart Block to emphasize the possibility that the actual block universe may be a more intricate thing than our current reconstructions of it. If you have a name in mind, go ahead, attache a name to it.
As you have certainly realized, the blocks are not as independent or mutually exclusive of each other, as they are presented. We already encountered the necessity for the Many Worlds Block to team up with the Laplace Block, since it cannot rely on a Space-Time Block. But the Space-Time Block, on the other hand, may be a perfect Laplace Block, streaky as it is with all its sneaky world lines.
And while one would think that the Two-Time Aharonov Block goes best with the Minkowski Space-Time Block, there’s actually a successful bastard with the Many Worlds Block*, which is pure Laplace of course. But then, there are efforts to reconstruct space out of the quantum realm, and with space Minkowski could be in on the Laplace-side as well.**
So there occurs the question, whether you could potentially collapse all this distinctions into one and the same block universe.
Well, the way I see it is that we are using these distinctions as probes; driving lines of investigation into a mystery that we label the Block Universe. So, of course you have the right to collapse and regain these distinctions, to refine and change, to dismiss and replace them.
Do what you have to do! This construction kit is fully customizable!
But, wait! What about the existential blocks? Do the Dark Block and the Smart Block show some affiliations, too?
Okay, I will say this: For me the Minkowski Space-Time Block feels more open, since it seems to sport a more holistic approach. You don’t have to explain how and why people and language and thoughts are made of the tiniest wavicles and are consistently determined throughout all time with the help of a compulsive demon.
People and language and thoughts are already there, and I’m not sure whether there really has to be a Laplacian determination at play in a Minkowski Block. The whole thing is too strange, with its every moment taking place forever, and a looping connectivity that’s mirroring the past into the future and the future into the past. That’s plus Aharonov, then; right.
However, for me that smacks of holistic determination beyond the particular determination vectors. And while this does not exactly feel like freedom, for some reason it does feel less narrow. Less fixed, even. In other words: Maybe there’s a potential Smart Block hiding in the Minkowski/Aharonov Block.
But hey, I’m out anyway. Not for one second do I believe that we live in a block universe. There is no way to determine a self-referential system externally, apart from destroying it.
That said, the cosmological scope and quantum depth of field of the block concept is impressive. I had a lot of fun with it and am grateful for the lesson in 20th century physics. It is the best model for temporally anomalous phenomena so far.
Respect for that, block universe.
The Soft Block
Audio-clip taken from: https://youtu.be/FVINOl0Ctfk
The Hard Block
Audio-clip taken from: https://youtu.be/idsw99SSwKc
The Many Worlds Block
Audio-clip taken from: https://youtu.be/gpEvv349Pyk
*I know, it’s usually spacetime, but that’s ugly. Worse: Compound words have their emphasis on their last term, and that’s exactly not what is meant here. Maybe that’s why it’s ugly for me. Grammar interferes with semantics.
** Love those guys: https://youtu.be/w3TDO1AA1Sw
The Two-Time Block
No articulate advocators yet. My sources:
Yakir Aharonov Two-time interpretation of quantum mechanics (2005)
Yakir Aharonov The Two-Time Interpretation and Makroscopic Time-Reversibility (2017)
*On weak measurements: https://youtu.be/aKR0ADUhjNE
The Dark Block
Sound-clip taken from: https://youtu.be/rK4Dq8Wwsd8
The Smart Block
Or the Non-Trivial Block, if you will.
*Lev Vaidman argues that the Many Worlds Interpretation is the natural companion for the Two-State Vector Formalism: Time Symmetry and the Many-Worlds Interpretation (2009)
** Sean Caroll gives an introduction about 37:00 of the video you already encountered as the source for the Many Worlds audio-clip: https://youtu.be/gpEvv349Pyk
For the frozen-in-time bird picture I ruined an image by a guy named Benjamin DeYoung.
The diagrams I drew myself.