I’ve been interested in physics since I was a kid, and read many books on the topic. The thought experiments of Einstein that led to his theories of relativity were some of the earliest topics I encountered. If you have not read of that, do so . . . I will wait.
So we come to the EPR paradox. The new field of quantum mechanics in the 1920s presented this conundrum - that particles could have entangled properties but that those properties would not become determined until a measurement event, at least according to Bohr. But upon one measurement, both particles states would be determined even if they were separated, and this determination would be instantaneous - faster than light.
The EPR paradox received further attention in the 1950s and led to the Bell’s Inequalities - describing the paradox in some detail. Bell proposed solutions to the paradox which are each a bitter pill in their own way. Some have received greater press, but there is nothing yet known to choose among them. Two that are most conspicuous are 1) a multiverse - all the outcomes exist in separate parallel universes, and 2) hard determinism - the paradox arises from quantum mechanics being predictive, but spacetime is complete and only one outcome actually exists - always has and always will.
The more I have thought on these options, the less possibility I can grasp for matters spiritual. The multiverse scenario seems ridiculously uneconomical to my admittedly-Calvinist upbringing, but if all outcomes exist, what judgement can there be for how a person lives (i.e. we live in ALL the ways we can). The hard determinism scenario is crystalline. We do not actually have any free will whatsoever - not even the free will to take advantage of being completely inculpable for our actions.
I think there may be a more mystical way of thinking of hard determinism though - a koan, if you will. We are agents of causality within a complete four-dimensional spacetime. We bring the crystalline structure of the universe into existence by virtue of our own existence in some way. <further mumbo-jumbo here>
Right, I was saying a quantum 90%/10% coin as shorthand for something like “arrange a magnetic field in z+ direction, shoot electrons through it, collecting those that deflect in direction consistent with spin up, then, without disturbing the electrons otherwise, shoot them through a second magnetic field inclined 28.8° away from z+ and count the number spin-up vs. spin-down”. Specifically to avoid getting distracted by questions like whether a cointoss is quantum-random or merely mechanically-random. Sorry if that wasn’t clear.
in your quantum multiverse, there is an important distinction to be made between mechanically-random and quantum-random; but in my hard-deterministic universe, the distinction, while maybe of some metaphysical interest - is immaterial, since both mechanisms are striving to predict an inescapable outcome. ;)
Ok, so why did you even bring up quantum in the first place? I thought you wanted to talk about EPR and Bell inequalities, but you were just focused on hard determinism?
Forget the quantum coin. Let’s use a regular 6-sided die. No quantum woohoo. You pick: sixes or not sixes? We roll the die, if you guess right I give you a dollar, if you guess wrong you give me a dollar. We’ll keep rolling until you run out of money or I grow bored.
You say you are living in block time and all rolls, past present and future, are already predetermined and nothing you can do or choose will change that. Whatever you pick, it doesn’t affect your probability of winning, because there is no probability - either you were already destined to win on the next roll, or you were destined to lose. Indeed your pick itself was pre-determined and you have no free will to consider one choice over another.
So here, I’ll make the choice for you. Before we start our game, I’ll give you one dollar for free if you make a commitment to always pick sixes. This is a strict advantage for you, because regardless of your future wins and loses (which you can’t influence), you’ll always at least have this extra dollar.
Ready to play?
This is what I find so interesting about the topic! Hard determinism is constrained by causality. Although the future is fixed, the events that transpire are causally linked to the past, and we seem like active agents of decisions. So since I am not a gambler, I never participate in wagers even though the outcomes are predetermined (or in my case the lack of wagers is predetermined). We are having this discussion in the context of the atheism community, so I think it is worth mentioning that there seems to not be much space in either hard determinism or a multiverse for the sort of spiritual-guidance and enforcement mechanisms proposed by religions. And yet, there may be a kind of mysticism to ponder whether we consider ourselves a more or less thick outcome slice, or whether we are agents of cause in a predetermined block time.
Did I bring up quantum? Well, if I did it was in the context of explaining Bell’s “solutions” to the EPR paradox. He thought there were three, as I recall, and he ruled one of those out. He ruled out hidden variable. So multiverse or hard determinism were all he had left. He did not care for hard determinism but he did not say why, as far as I know.
So since I am not a gambler, I never participate in wagers even though the outcomes are predetermined
I knew you were going to say this!
Do you know how I know? Because that’s the problem with hard-determinists - deep down you don’t really believe it. In your mind you have calculated the probabilities you claim don’t exist, and in your heart you fear I would clean you out. And you are damn right I would! That’s why I sweetened the deal by paying you one dollar up front. This way, choosing to play the game is a dominant strategy… for you. I’m not a gambler myself, never have gambled in my life, but if some crazy-but-honest hard-determinist millionaire offered me this sixes game, and paid me on top of that to commit to not-sixes, I would jump into it in a heartbeat. If you truly believed, you would have no fear.
In real life you don’t get the privilege not to gamble. You gamble every time you take an umbrella (or not) when going outside. You gamble every time you cross the street. Every action you take is guided by frequentist thinking. And this one time you just completely arbitrarily in a pre-determined way “decided” not to play my game? Ha! I have predicted this. So much for the future being determined but unpredictable!
There was a time we thought Earth was the only terra firma, then we discovered that the wandering stars were actually planets, some bigger than ours.
There was a time we thought the Sun was singular, then we discovered that every star in the sky is a sun, a galaxy full of them, some bigger than ours.
There was a time we thought that our galaxy was the whole universe, then we discovered that most every fuzzy nebula is a distant galaxy, some bigger than ours.
A hundred billion galaxies, each with a hundred billion stars - and those are just the ones we can see within our horizon! - all to support a bunch of hairless apes? Turns out the universe has no care for economy of stuff. At every step in history of science you could have made an argument of economy, and you would have been wrong. The universe seemingly only cares for economy of rules. Four forces, twelve fields - enough to describe everything that is.
Is it that great of a leap to take one more step and accept that our experience is but one branch of a mind-breaking multitude of the many-worlds branching tree? There is exactly one rule that controls them all - the Born Rule - that’s the kind of economy the universe likes.
I think it IS that great a leap - all the steps before have been steps of magnitudes - we kept finding it was way bigger. But the multiverse idea is one of parallelism - that our universe is one of infinitely many; each way bigger that we could imagine. There IS an economy of stuff in at least THIS universe - a finite quantity, albeit mind numbingly much. My ancestors mutter “enough is enough!” lolz
There IS an economy of stuff in at least THIS universe - a finite quantity
If it helps assuage your sentiment: the Born Rule enforces a finite quantity of total probability - namely 1. The branching does not create new universes, it merely splits the existing universe thinner, each given 50% (or however much) amplitude. That probability cannot be created or destroyed is a mathematical consequence of the Schrodinger equation.
The you and me here is one small blob of probability, one 10999…999th part of the original universe, but NOT an infinitesmall part - merely finitely small.
each way bigger that we could imagine
You misspoke here - every slice is exactly as big in extent of space as every other, namely one Hubble volume. That probably IS bigger than we could imagine, but that’s not related to quantum mechanics.
hmm . . . the existing universe; thinner in what respect? the total probability of all outcomes is 1, but in each individual spacetime, there is also an outcome probability of 1 for the future that actually transpires . . . much to contemplate here.
thinner in what respect?
“Thinner” with respect to the Born rule :) It’s like if time were a reel of movie film, except that the film had noticeable thickness, say 1cm. Every point in the movie where there is a macroscopic divergence due to a quantum effect is like shearing the film in half, so now you have two ribbons of film each 5mm thick. Like the movie begins with you setting up a machine to measure the spin of an electron along a fixed axis, then the film splits and one movie ribbon continues showing where the dial on your instrument points “up” and in another half-thickness movie ribbon the dial points down. You can conduct more experiments and get more and more shears down to 2.5mm, 1.25mm, etc. Or, if the experiment is set up in such a way that outcomes are not 50/50 but say 90/10, then the first shear is into 9mm and 1mm, the second shear is 8.1mm, 0.9mm, 0.9mm, and 0.1mm, etc - a crazy medusa head of split hairs.
It is not yet clear what this “thickness” or, in another sense, “reality fluid” really is. All we know is that it obeys the Schrodinger equation and that its amplitude[1] we get at the end of our calculation is exactly equal to the probability of our outcomes. As in, if we look backwards at our film’s history, we have ended up in the thicker ribbon of film more often than in the thinner one. And remember, the outcomes don’t need to be 50/50, you could set them up to be 90/10. This can’t be explained by something like the binomial distribution of a pachinko machine - the 90% outcome really carries some weight to it, some extra thickness of reality.
Or more specifically and even more oddly, the square absolute magnitude of the amplitude, which itself is a complex number ↩︎
OK, but if I am put in a box with a radioisotope, a sensor, a hammer and a vial of poison; and I survive the ordeal; my reality will be as real to me and my wife as the other reality where she goes to my funeral too early. Each of those realities - those universes will be equally whole and complete; except for this aspect of thin-ness? If an outcome has a very low probability, in a quantum event, so that it would be remarkably “thin”, it will still be a whole separate universe with all the rights and privileges, etc.? So is thin-ness perceptible from within a universe or only a property observable from some higher vantage?
The thin-ness is directly observable retrospectively. We look at our past history and see that we find ourselves in a branch that is much thicker than many of the other possible branches. If we look backwards in time at all the experiments we have ever done, we always mostly end up in the thicker branches than in the more numerous branches. There are versions of us in the thin branches, yes, but we are not them.
For example, imagine you had a weighted quantum 90/10 coin that landed heads 9 times out of 10 on average, and you flipped it 1000 times. If you were just counting distinct universes (thinking that “each universe will be equally whole and complete”), you have 2^1000 distinct branches. Of those, using the binomial theorem, you’d expect that in 99.8% of them the number of heads you see will be between 450 and 550. However, you will most likely not see that. There is a 99.8% chance that you will see at least 870 heads.
If you think that each branch is whole and complete, you cannot explain this. You’d expect to find yourself equally in every branch since they are “all equally distinct”, but in practice you do not. You might claim you were just super-lucky that time, but most every time you repeat the experiment you will end up with the same lopsided result. It is as if there is some additional variable you are missing, some value to assign to each branch to describe how “real” it is! That variable is the amplitude, the Schrodinger equation is how you calculate its evolution in time, and the Born rule tells you how to square it to calculate the probability value you need.
This is why I think of probability as “thickness” of the universe. We are just too fixated on counting distinct options, it’s hard to think in any another way. So I imagine this thick reel of film, where all the ribbons are identical and stuck together up to the point where some quantum measurement happens, and then some of the ribbons peel off into diverging plotlines. This way you can still count individual “ribbons”, it’s just that a bunch of ribbons in a thick bundle all carry an identical movie. After some time you may finally stop caring about counting individual ribbons and just take a thickness measurement instead.
I find my hard determinism so much more comforting - there was always a 100% chance I would end up right here! I am right where I am supposed to be, where I *must * be. All those other outcomes, probable or improbably though they may have seemed, they had zero chance! Mere figments of my imagination.
I haven’t given this a lot of thought, but here are some things that spring to mind – I’m open to a more in depth conversation around this.
I think it’s a stretch to apply anything which happens on a quantum level to larger particles or collections of particles. It’s difficult enough to keep multiple qubits in sync under tightly controlled conditions in a quantum computer – extrapolating quantum behavior to a human being running loose in the universe seems to missing a step or two in the middle.
Sure, photons go through both slits in the double-slit experiment, but when I try to walk through both the enter and exit doors of the supermarket, I usually bump into the wall between them, whether or not someone else is looking at me.
At the risk of being simplistic (and I’m aware this argument is not rigorous at all), does a flock of birds act like a single bird? A school of fish? A group of people? One electron is just there – billions of electrons can light up a room.
Again, I haven’t delved deep into this, but I think what we casually perceive as reality – the classic Newtonian universe with solid things moving around and falling onto people’s heads – is the average of all these little quantum things going on down at Planck scale. All these entanglements and tunnels and spontaneous particle creations average out to give us something that looks like an electron or a proton, and put enough of those together and you’ve got a gaseous cloud that behaves differently than the individual quantum elements.
Anyway, just my US$0.02. Your mileage may vary, void where prohibited by law, terms and conditions apply, close cover before striking, and I may be completely wrong.
the things which happen on quantum level can affect the larger outcomes - a photon is emitted or it isn’t and we can choose actions based on that outcome. In a lot of situations, large numbers of quantum events contribute to the outcome - and I believe they refer to that as “quantum degeneracy”, basically it does not matter which quantum event(s) contribute; the outcome will be the same. So a rock behaves in ways that belie its quantum composition. But we do not know where the dividing line is; where quantum degeneracy ceases. It might happen in the nerve system that single quantum events cause bifurcations in outcome chances.
