And I'm a dick. — Banno

Does that mean it would be fun to play with you, but not in public? :joke:

Of course. But I am very selective of my playmates.

I wonder... Could the laws of physics not be such that the outcomes are not fixed; and yet, since in your thought experiment we are re-running time, the outcome stay the same?

Put differently, we've pretty much concluded that events in the future are not fixed by the state of the universe now. Does that invalidate the notion of block time?

But I am very selective of my playmates. — Banno

As you should be!

Put differently, we've pretty much concluded that events in the future are not fixed by the state of the universe now. Does that invalidate the notion of block time? — Banno

I’d say it requires multidimensional time.

The universal wavefunction does evolve deterministically, but that wavefunction is itself a multidimensional construct containing an ensemble of possible states of the universe. So that kind of gets you to quantum block time in a more conventional way there.

But my preferred way to think of it is to envision time as a path through the configuration space of the universe, which I take to mean a different kind of modal realism. Other possible worlds (in a Kripkean sense but not a Lewisian sense) are the exact same thing as other times; futures and pasts are just other possible worlds that bear a particular kind of relationship to this present actual world.

Interesting, and a whole new kettle of salmon. I'm agin just equating modal possibilities with quantum possibilities - at least not without a conversation, and maybe flowers.

Modal possible worlds are created by an explicit act of "what if...". that's quite different from a collapsing wave function...

You are asserting that determinism is the case. I am not asserting that it is not the case, but that we have no way of knowing either way — Janus

Because you failed to explain consciousness and measurements properly, both of which are a causal processes.

What determines that we cant know either way?

Can't we have both? Some things are deterministic, some aren't. — jorndoe

This is basically dualism and all the problems it brings, like how deterministic and indeterministic things interact - deterministically or indeterministically?

Put differently, we've pretty much concluded that events in the future are not fixed by the state of the universe now. Does that invalidate the notion of block time? — Banno

Depends on what you mean.

1. Events in the future are (not) fixed by the state of the universe now. I read this as implying that there is a uniquely correct theory (not necessarily known to us) that describes events in the past and in the future, and that the theory is (in)deterministic.

2. Block time. This is often taken to mean that events in the past and the future exist in some sense.

Setting aside the truth of (1) and the meaningfulness of (2), it is clear that (1) has no implication on (2). One can be a determinist and a presentist, i.e. believe that although future events are fixed by the present, they do not have the same ontological status. Or one can be indeterminist and yet subscribe to block time. The fact that no correct theory fixes the future given the present does not imply anything about the future's ontological status.

Note that I only talk about these positions as actual positions that some people hold. Personally I am very skeptical about the meaningfulness of presentism/eternalism debate, and somewhat skeptical about determinism/indeterminism.

So, where would we start? Rocks are deterministic, and human beings are not? How about a mosquito? — Metaphysician Undercover

We go by evidence. Say, findings like planetary orbits, quantumatics, ..., whatever. The world doesn't care about our metaphysics or whatever we think. Rather, our beliefs are the adjustable parts.

We go by evidence. Say, findings like planetary orbits, quantumatics, ..., whatever. The world doesn't care about our metaphysics or whatever we think. Rather, our beliefs are the adjustable parts. — jorndoe

So our beliefs are determined by evidence? If not, then what determines what you believe? If I asked you why you believe in something, wouldn't you provide me reasons for what you believe, and those reasons would determine what you believe, no?

We go by evidence. Say, findings like planetary orbits, quantumatics, ..., whatever. The world doesn't care about our metaphysics or whatever we think. Rather, our beliefs are the adjustable parts. — jorndoe

OK, so the evidence as I see it, indicates that rocks are deterministic, and human beings are not. It appears to me that mosquitoes are not deterministic either. Nor do plants appear to be deterministic. So I think that inanimate things are deterministic, and living things are not. Do you agree?

What determines that we cant know either way? — Harry Hindu

We cannot examine microphysical processes such as to be able to decide if they are truly uncaused or not. The consensus among the experts seems to be that they are uncaused. If you can outline a method whereby we could do that examination, down to ever-smaller scales, I'm prepared to listen.

The other thing is that if, for example, radioactive decay turned out to be caused, if we discovered and were able to observe the cause, then we would still be left with the question as to what caused that cause...and so on ad infinitum. We could never know whether we had arrived at the "first cause", and if we had it, logically, would have to be uncaused in any case.

We cannot examine microphysical processes such as to be able to decide if they are truly uncaused or not. The consensus among the experts seems to be that they are uncaused. — Janus

But the microphysical is really the same reality as the macrophysical, just from a different view, and the macrophysical is deterministic and includes humans and their thoughts, beliefs and views. So, as I've been saying, I think that a proper explanation of consciousness could help to unify the different views into a consistent whole. We are missing crucial information to make sense of these contradictory views.

We could never know whether we had arrived at the "first cause", and if we had it, logically, would have to be uncaused in any case. — Janus

Or that there is a causal loop. Think about the causal relationship between predators and prey.

But the microphysical is really the same reality as the macrophysical, just from a different view, and the macrophysical is deterministic and includes humans and their thoughts, beliefs and views. So, as I've been saying, I think that a proper explanation of consciousness could help to unify the different views into a consistent whole. We are missing crucial information to make sense of these contradictory views. — Harry Hindu

Sure we could come up with better explanations, but no matter how good any explanation is it could never prove "rigidly" or absolutely deterministic causation, even in regard to the "macro'.

Or that there is a causal loop. — Harry Hindu

How would that would work? Take the example of radioactive decay; when the particle is emitted either it is uncaused or it is the result of something else acting on it to make it happen. If something else acts on it to make it happen, are you suggesting that "something else" could be acted upon by the radioactive particle itself in order to make the unknown agent in turn act upon the particle?

Maybe this was already discussed in this thread - but why do people seem to think that free will and determinism are incompatible.

It is only the assumption that free will comes from outside of the natural universe which is incompatible with determinism. Who you are, your pattern still has agency and makes decisions its just that they are predictable to a perfect predictor, which is normative...

Sure we could come up with better explanations, but no matter how good any explanation is it could never prove "rigidly" or absolutely deterministic causation, even in regard to the "macro'. — Janus

What would proof of determinism or indeterminism look like? It seems to me that if the latter were true, our posts wouldn't continue to exist in the original state long enough to have a conversation, much less be able to make any predictions, except by luck and our success rate using the theories we have is much higher than 50% - that smart phones wouldn't work so well for so many. If indeterminism were true, why would we ever have any evidence for determinism?

It seems to me that if the former were true then we can have meaningful conversations, predict events whose success depends on our level of understanding of the event in question. You have to acknowledge the fact that understanding and ignorance seem to go hand in hand with determinism and randomness - and that the understanding of some event can be carried over to similar events, not dissimilar events. So, while we may not be able to prove determinism, we seem to have a good amount of evidence for it. If indeterminism were true, what use is an explanation? It seems to me that determinism can be true and we can also be ignorant, which would look like what we have now - predictable patterns that we have to learn before being able to predict, and that ignorance of some pattern can make the pattern appear unpredictable, or random.

How would that would work? Take the example of radioactive decay; when the particle is emitted either it is uncaused or it is the result of something else acting on it to make it happen. If something else acts on it to make it happen, are you suggesting that "something else" could be acted upon by the radioactive particle itself in order to make the unknown agent in turn act upon the particle? — Janus

Sure, ever heard of the observer effect? And it doesn't have to be that simple of a loop. There could be other processes involved that make it more complex where there is more than the radioactive decay and a "something else" involved.

True backward causation introduces true randomness (even if the universe was otherwise deterministic, the moment that information from the future arrives introduces a fork in the timeline, and from the perspective of someone living through that moment it’s random which timeline they “end up in”). So it seems that something that seems to approximate backward causation (ordinary prediction) would in turn introduce something that looks approximately like randomness, i.e. chaos, even if everything was technically strictly deterministic. — Pfhorrest

Actually not quite. In fact, one of my preferred interpretations of QM has precisely this backward causality, along with normal forward causality. The condition that stops what you expect is self-consistency. The question remains then as to what laws of physics guarantee this self-consistency.

An example is matter-antimatter pair creation and annihilation. A photon excites the electron field temporarily, leading to an electron and positron being created which then attract one another and annihilate. If the photon is energetic enough, the electron and positron can be created with sufficient kinetic energy that they escape one another's attraction and become 'real'. But there is a charge-parity-time symmetry in the universe that is obeyed in this phenomenon: a spin-down positron is just a spin-up electron moving backwards in time. (This is true of all antimatter.) Taking the electron's PoV where energy is insufficient to become real, it is excited from the vacuum, then spontaneously emits a photon of twice its own energy and reverses direction in time to conserve energy. It then does it again to change direction to our normal forward direction in time, and it follows this causal loop for an infinite number of iterations. From the outside, a pair is created then annihilated, and that's that.

The transactional interpretation of quantum mechanics interprets the complex conjugate of the wavefunction to be a wavefunction going backwards in time. (Which is not unreasonable: the wavefunction has an exponent proportional to i*t -- the imaginary number multiplied by time. Taking the complex conjugate [i*t --> (-i)*t] and reversing the direction of time the wave travels through [i*t --> i*(-t)] are mathematically identical, and therefore equally valid.)

Self-consistency is easier to arrive at in this case because the wavefunction itself is not measurable, but the probability density (via the Born rule) is. A photon being emitted from an atom, for instance, will deterministically spread outwards in all or many directions at once. Where that wavefunction encounters other atoms that can absorb it, those atoms emit photons whose wavefunctions move backwards in time (photons are their own antiparticles: a backwards emission is identically an absorption). The only "cause" consistent with the "effect" is the original atom that emitted the forwards photon. This self-consistency is maintained by the requirement that real phenomena have wavefunctions that are not orthogonal to each other. It is the same process of elimination that stops the cat being in a state of dead when radioactive decay has not occurred.

In principle, this back-and-forth could evolve over an infinite number of iterations, with certain paths initially tried by the original photon ironed out (sum over histories) until we're left with a single set of trajectories with the same cause and the same effect(s). Not knowing the future, we can only consider the forward propagation and cannot explain the decisiveness of the effect (the measurement problem).

If you mean macroscopically, like the grandfather paradox, I would suggest that the above, if true, would be subject to the same classical limit as all quantum effects. A person is, while technically a wave, not wave-like, period being inversely proportional to mass. Any back and forth jiggery-poker would have to occur at insanely, maybe impossibly small timescales.

a spin-down positron is just a spin-up electron moving backwards in time. (This is true of all antimatter.) — Kenosha Kid

Nice commentary, Kid. In 1954 I wrote a short paper on this for my physics class in high school. At the time I loved reading science fiction. Of course, the technical details were beyond me, but my teacher, an elderly lady we all loved was impressed. :cool:

Nice commentary, Kid. In 1954 I wrote a short paper on this for my physics class in high school. At the time I loved reading science fiction. Of course, the technical details were beyond me, but my teacher, an elderly lady we all loved was impressed. — jgill

Thanks! Yeah I ended up doing a physics simply because I couldn't get past the mathematics of the physics books I wanted to read. For the love of gawd, someone needs to invent an easier way to do physics than maths! Glad your teacher liked it, she sounds like a cool old lady.

That the macro world seems deterministic to us is, according to QM, most likely because countless stochastic micro-physical processes by purely chance statistically add up to seem deterministic and are thus predictable.

Sure, ever heard of the observer effect? And it doesn't have to be that simple of a loop. There could be other processes involved that make it more complex where there is more than the radioactive decay and a "something else" involved. — Harry Hindu

The problem with this is that we are discussing a single microphysical event, and you are claiming that every simple event has a proximate and rigidly determining cause. If the cause were just the general global or local conditions, then that would not be saying anything other than that the particular lump of radioactive matter in its particular conditions caused the particle to emit, which tells us pretty much nothing except that the conditions were the conditions.

I can't see what the observer has to do with it. Are you saying the observer causes the particle to emit? How would that work?

That the macro world seems deterministic to us is, according to QM, most likely because countless stochastic micro-physical processes by purely chance statistically add up to seem deterministic and are thus predictable. — Janus

I don't understand how countless stochastic micro-physical processes could produce an entity in the macro world which perceives a world that is inherently stochastic, as non-stochastic, by chance. It requires mental gymnastics that my mind isn't capable of performing.

But there is a charge-parity-time symmetry in the universe that is obeyed in this phenomenon: a spin-down positron is just a spin-up electron moving backwards in time. — Kenosha Kid

This is a strange concept. How does some part of the universe move backwards in time while another part moves forward? I thought time was really just a change, and that change relative so some other change is how we measure change/time. So any change some positron undertakes is always a move forward in time. How can something in the universe change "backward" while the rest of the universe is changing "forwards", or is this concept of time inaccurate, or inapplicable in QM?


,,
Also, about the "observer effect", when observing the behavior of electrons and protons, how do we know that the changes we observe are actually changes in the states of what we are looking at rather than something more to do with how consciousness works and perceives/measures quantum-sized processes? It seems to me that if observing these tiny processes changes them, rather than the change we perceive has more to do with how our minds perceive and model quantum processes, then the old model of explaining vision as shooting beams from your eyes to see would more accurate. Either that or these quantum processes "know" when they are being looked at, which seems to indicate some sort of panpsychism.

Are you claiming that looking at a lump of uranium could cause a particle to be emitted? How do you imagine that could work?

I wasnt claiming anything at all. I was asking you and Kenosha if the observer effect has more to do with how observations/consciousness behaves rather than how quantum particles behave when being observed.

The observer effect is a theory of QM. I find the fact that you are now thinking QM theories are incredulous when you have been promoting QM as a means of discrediting determinism, yet you think that observing, thinking entities can emerge from uncaused processes to observe causation, by chance..

In her conclusion, Anscombe wrote: "it ought not to have mattered whether the laws of nature were or were not deterministic"
Because Anscombe uses the words determine, determinate, determined, determinism and deterministic without prior explanation, it sometimes makes it difficult to follow her argument.
For example, if the path of one ball (in the Galton Board) is determined by its initial state and the laws of nature (such as cause and effect), then nature is deterministic, not the laws of nature.
Cause and effect is a law of nature. If an effect is determined by a cause, then determinism is a law of nature.
Therefore, contrary to Anscombe, the laws of nature are not deterministic.

Hence my point that QM and classical physics need to be unified - kind of like how genetics and the theory of evolution by natural selection are unified micro and macro theories that support each other, not contradict each other like QM and classic physics. The glue to unify them, IMO, would be a proper theory of consciousness. — Harry Hindu

Why consciouness, of all things?

The so-called observer effect or problem in QM has nothing specifically to do with the idea that the microphysical is indeterministic, other than the fact that both ideas occur in QM.

Anscombe uses the words determine, determinate, determined, determinism and deterministic without prior explanation, — RussellA

The whole of the article is a discussion of the use of these terms. You would have her explain the article prior to beginning it?

I was asking you and Kenosha if the observer effect has more to do with how observations/consciousness behaves rather than how quantum particles behave when being observed. — Harry Hindu

In a double slit experiment, there's "a setup" where you see an interference pattern and "another setup" where you do not. So (a) conscious observers can tell the difference between seeing an interference pattern and not seeing interference patterns. Suppose then that consciousness had something to do with QM; one would then think one could (b) create a setup such that if an observer (subject) was conscious, the (conscious) experimenter would see no interference pattern, but if the observer (subject) had no consciousness, the (conscious) experimenter would see one.

(b) is actually quite a powerful result; it is tantamount to a test for consciousness. We don't actually have (b) though; if we did, it would be a lot more powerful than simply making a strange theory few people understood... we'd be putting everything from tardigrades to puppies in the thing testing which entities had consciousness.

I believe that Anscombe's use of the word "deterministic" is different to common usage.

Throughout her article, Anscombe states that the laws of nature are deterministic, not that nature is deterministic, e.g., "It ought not to have mattered whether the laws of nature were or were not deterministic".

In mathematics, computer science and physics, it is the system that is a deterministic, i.e., its initial state plus the physical laws as described by equations.

Similarly, it is nature that is deterministic, i.e., its initial state plus the laws of nature. The laws of nature by themselves cannot determine anything. The laws of nature by themselves are not deterministic.

It may well be that given Anscombe's particular usage of the word deterministic, her argument is logical and her conclusion sound

However, the general reader who believes that they know the common usage of the word deterministic may find her argument unclear.

In such a case, where the author uses a word in a way that is different to common usage, then the author should explain what they mean by the word at the beginning of their article.