Saturday, February 27, 2021

Schrödinger’s Cat – Still Not Dead

[This is a transcript of the video embedded below.]

The internet, as we all know, was invented so we can spend our days watching cat videos, which is why this video is about the most famous of all science cats, Schrödinger’s cat. It is really both dead and alive? If so, what does that mean? And what has recent research to say about it? That’s what we’ll talk about today.

Quantum mechanics has struck physicists as weird ever since its discovery, more than a century ago. One especially peculiar aspect of quantum mechanics is that it forces you to accept the existence of superpositions. That are systems which can be in two states at the same time, until you make a measurement, which suddenly “collapses” the superposition into one definite measurement outcome.

The system here could be a single particle, like a photon, but it could also be a big object made of many particles. The thing is that in quantum mechanics, if two states exist separately, like an object being here and being there, then the superposition – that is the same object both here and there – must also exist. We know this experimentally, and I explained the mathematics behind this in an earlier video.

Now, you may think that being in a quantum superposition is something that only tiny particles can do. But these superpositions for large objects can’t be easily ignored, because you can take the tiny ones and amplify them to macroscopic size.

This amplification is what Erwin Schrödinger wanted to illustrate with a hypothetical experiment he came up with in 1935. In this experiment, a cat is in a box, together with a vial of poison, a trigger mechanism, and a radioactive atom. The nucleus of the atom has a fifty percent chance of decaying in a certain amount of time. If it decays, the trigger breaks the vial of poison, which kills the cat.

But the decay follows the laws of quantum physics. Before you measure it, the nucleus is both decayed and not decayed, and so, it seems that before one opens the box, the cat is both dead and alive. Or is it?

Well, depends on your interpretation of quantum mechanics, that is, what you think the mathematics means. In the most widely taught interpretation, the Copenhagen interpretation, the question what state the cat is in before you measure it is just meaningless. You’re not supposed to ask. The same is the case in all interpretations according to which quantum mechanics is a theory about the knowledge we have about a system, and not about the system itself.

In the many-worlds interpretation, in contrast, each possible measurement outcome happens in a separate universe. So, there’s a universe where the cat lives and one where the cat dies. When someone opens the box, that decides which universe they’re in. But for what observations are concerned, the result is exactly the same as in the Copenhagen interpretation.

Pilot wave-theory, which we talked about earlier, says that the cat is really always in only one state, you just don’t know which one it is until you look. The same is the case for spontaneous collapse models. In these models, the collapse of the wave-function is not merely an update when you open the box, but it’s a physical process.

It’s no secret that I myself am signed up to superdeterminism, which means that the measurement outcome is partly determined by the measurement settings. In this case, the cat may start out in a superposition, but by the time you measure it, it has reached the state which you actually observe. So, there is no sudden collapse in superdeterminism, it’s a smooth, deterministic, and local process.

Now, one cannot experimentally tell apart interpretations of mathematics, but collapse models, superdeterminism, and, under certain circumstances, pilot wave theory, make different predictions than Copenhagen or many worlds. So, clearly, one wants to do the experiment!

But. As you have undoubtedly noticed, cats are usually either dead or alive, not both. The reason is that even tiny interactions with a quantum system have the same effect as a measurement, and large objects, like cats, just constantly interact with something, like air or the cosmic background radiation. And that’s already sufficient to destroy a quantum superposition of a cat so quickly we’d never observe it. But physicists are trying to push the experimental boundary for bringing large objects into quantum states.

For example, in 2013, a team of physicists from the University of Calgary in Canada amplified a quantum superposition of a single photon. They first fired the photon at a partially silvered mirror, called a beam splitter, so that it became a superposition of two states: it passed through the mirror and also reflected back off it. Then they used one part of this superposition to trigger a laser pulse, which contains a whole lot of photons. Finally, they showed that the pulse was still in a superposition with the single photon. In another 2019 experiment, they amplified both parts of this superposition, and again they found that the quantum effects survived, for up to about 100 million photons.

Now, a group of 100 million photons not a cat, but it is bigger than your standard quantum particle. So, some headlines referred to this as the “Schrödinger's kitten” experiment.

But just in case you think a laser pulse is a poor approximation for a cat, how about this. In 2017, scientists at the University of Sheffield put bacteria in a cavity between two mirrors and they bounced light between the mirrors. The bacteria absorbed, emitted, and re-absorbed the light multiple times. The researchers could demonstrate that this way, some of the bacterias’ molecules became entangled with the cavity, so that is a special case of a quantum superposition.

However, a paper published the following year by scientists at Oxford University argued that the observations on the bacteria could also be explained without quantum effects. Now, this doesn’t mean that this is the correct explanation. Indeed, it doesn’t make much sense because we already know that molecules have quantum effects and they couple to light in certain quantum ways. However, this criticism demonstrates that it can be difficult to prove that something you observe is really a quantum effect, and the bacteria experiment isn’t quite there yet.

Let us then talk about a variant of Schrödinger’s cat that Eugene Wigner came up with in the nineteen-sixties. Imagine that this guy Wigner is outside the laboratory in which his friend just opens the box with the cat. In this case, not only would the cat be both dead and alive before the friend observes it, the friend would also both see a dead cat and see a live cat, until Wigner opens the door to the room where the experiment took place.

This sounds both completely nuts as well as an unnecessary complication, but bear with me for a moment, because this is a really important twist on Schrödinger’s cat experiment. Because if you think that the first measurement, so the friend observing the cat, actually resulted in a definite outcome, just that the friend outside the lab doesn’t know it, then, as long as the door is closed, you effectively have a deterministic hidden variable model for the second measurement. The result is clear already, you just don’t know what it is. But we know that deterministic hidden variable models cannot produce the results of quantum mechanics, unless they are also superdeterministic.

Now, again, of course, you can’t actually do the experiment with cats and friends and so on because their quantum effects would get destroyed too quickly to observe anything. But recently a team at Griffith University in Brisbane, Australia, created a version of this experiment with several devices that measure, or observe, pairs of photons. As anticipated, the measurement result agrees with the predictions of quantum mechanics.

What this means is that one of the following three assumptions must be wrong:

1. No Superdeterminism.
2. Measurements have definite outcomes.
3. No spooky action at a distance.

The absence of superdeterminism is sometimes called “Free choice” or “Free will”, but really it has nothing to do with free will. Needless to say, I think what’s wrong is rejecting superdeterminism. But I am afraid most physicists presently would rather throw out objective reality. Which one are you willing to give up? Let me know in the comments.

As of now, scientists remain hard at work trying to unravel the mysteries of Schrödinger's cat. For example, a promising line of investigation that’s still in its infancy is to measure the heat of a large system to determine whether quantum superpositions can influence its behavior. You find references to that as well as to the other papers that I mentioned in the info below the video. Schrödinger, by the way, didn’t have a cat, but a dog. His name was Burschie.


  1. Schrödinger, Heisenberg, and Ohm are riding in a car. It is stopped by a policeman for going to fast. He says that they were going precisely 182.7 km/h. Heisenberg replies that he now has absolutely no idea where they are. The policeman, suspicious, searches the car, opens the boot, and tells them that they have a dead cat in there. NOW we do is Schrödinger’s reply. Due to their strange behaviour, the policeman arrests them. Ohm resists.

    More seriously, Schrödinger’s cat was used by Schrödinger as an example of the absurdities the Copenhagen interpretation leads to. Like Einstein, Schrödinger didn’t believe in an inherently indeterminate quantum mechanics. In his later years, like Einstein, he concentrated on unified field theories. (They also both had a thing for young female groupies.)

    1. Regarding Schrodinger and Einstein's behaviour, I wonder if there's an equation to show a causative correlation between how brilliant and eccentric one is, how ground-breaking and influential their ideas are, the adulation they receive, and how 'skeezy' they become.

    2. Schrödinger didn't use it in that way. He used his cat to warn against a particularly bad early idea of what the quantum state represents:

      It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naively accepting as valid a “blurred model” for representing reality.

      And 'the' CI doesn't lead to [such] absurdities. In the same paper - the famous Cat paper - he established what the (Bohr) CI does take the quantum state to represent: “the momentarily-attained sum of theoretically based future expectations, somewhat as laid down in a catalog…. It is the determinacy bridge between measurements and measurements”.

  2. One of the two celebrity idols of physics, presumably, said that “philosophy ... is about as useful to scientists as ornithology is to birds.”

    1. This comment has been removed by the author.

  3. But I am afraid most physicists presently would rather throw out objective reality.

    According to Wikipedia, the principle of charity "requires interpreting a speaker's statements in the most rational way possible and, in the case of any argument, considering its best, strongest possible interpretation". In that awful 'discussion' with yourself and others in the comments below your "A Philosopher Tries to Understand the Black Hole Information Paradox" blog article, I pointed out that "throwing out objective reality" is a gross distortion; a silly caricature. It's well known, at least among the quantum foundations-literate, that there has never been a need, let alone a desire, to "throw out objective reality". As I said there repeatedly, for (Bohr) Copenhagenists and neo-Copenhagenists (QBists, RIers etc.), and especially for those of us aware that there is more to probability theory than classical probability theory, what's (necessarily) rejected is a naive realism - "Realism_2", as R. F. Werner put it. I've no problem with your advocacy of superdeterminism but please stop misrepresenting the broadly "QM is just probabilistic mechanics" camp(s) as advocating, or being forced into accepting, an ostensibly absurd position.

    1. Paul, excuse me to interrupt you with my comment, but I will be brief: more and more cases of the so-called 'quantum paradoxes' was found being treated according to classical probabilistic interpretation. Einstein was once confused with 'remote action', but now we understand that this fact in itself is not surprising and explained well both in classic and quantum probability case. There are many cases of similar 'insights' along the way of developing our understanding of quantum nature. Until now, it is believed that the experiment with a delayed choice quantum eraser is of a purely quantum nature, and is not reproducible by classical emulation. But that's not entirely true, check out my blog for further explanation.

    2. Igor, it simply isn't the case that both, interpreted as probability, are capable of resolving the more interesting phenomena without resort to "spookiness". Quantum probability is, classical isn't.

      What we now understand is that "remote action" is a matter of interpretation rather than fact, but if all you have in your mathematical and philosophical toolbox is classical probability you won't be able to explain Bell inequality violations etc. without embracing some kind of weirdness on the mechanical side. [And it's not necessary to resort to elaborate experiments to see this.]

  4. If there is an objective reality and it is knowable I would have to know it through my sensory and cognitive apparatus. That apparatus evolved with a survival bias, not a "knowing" bias. More likely, what I am able to know is some sort of representation of an objective reality. The brain has crafted that representation, so now we descend into cognitive neuroscience issues. What we are able to know has been likened to an icon we can manipulate on our computers. The reality behind that icon is quite complex. So to what extent is that icon a good representation of an objective reality linked to it? If I understand the uses of that icon, what I can do with it by clicking it, to what extent do I know anything about the objective reality behind it?

  5. Sabine, if we look at what is taking place in the interim space between the slitted wall and the phosphorescent screen in the double slit experiment, where one electron is shot through the setup, allegedly (at least according to the Copenhagen Interpretation), the electron exists in a superpositioned state of what Heisenberg called a ghostly raw "potentia."

    in which case, it is the phosphorescent screen (the "measuring" part of the system) that instigates the collapse of the electron's wavefunction, thus promoting the electron from its "ghostly" (superpositioned) state and into something that we call "real" (a spot on the screen).

    However, as a thought experiment, if we could somehow stage the double slit experiment in an absolute vacuum and simply remove the phosphorescent screen, wouldn't the superpositioned wavefunction of the electron simply propagate forever (as a wave) until a measurement is made?

    And if so, wouldn't that be a clear indication that "measurements have definite outcomes"?

    1. Sabine wrote:
      "...As you have undoubtedly noticed, cats are usually either dead or alive, not both. The reason is that even tiny interactions with a quantum system have the same effect as a measurement, and large objects, like cats, just constantly interact with something, like air or the cosmic background radiation. And that’s already sufficient to destroy a quantum superposition of a cat so quickly we’d never observe it..."

      Sabine, you have taught me to never make any assumptions about the things you say.  Nevertheless, out of curiosity, are you alluding to "decoherence" in the above quote?

      If not, then please say so.  But if you are, then according to Wiki:
      "Decoherence was first introduced in 1970 by the German physicist H Dieter Zeh and has been a subject of active research since the 1980s.  Decoherence has been developed into a complete framework, but it does not solve the measurement problem, as the founders of decoherence theory admit in their seminal papers....Decoherence does not generate actual wave-function collapse...."

      Now you may have had something else in mind, but does the fact that the Wiki quote states that decoherence...

      "...does not generate actual wave-function collapse..." thus, "...does not solve the measurement problem..."

      ...have any bearing on what you said about the alleged collapse that occurs simply by cats interacting with "air" or "cosmic radiation"?

      After all, isn't it a fact that certain interpretations of quantum mechanics suggest that the "unmeasured" cosmic background radiation would itself exist in a state of superposition that would, in theory, be entangled with the "unmeasured" cat's superposition, and thus simply form a larger and more complex wavefunction that contains no inherent means for collapsing itself?

      Again, decoherence "...does not generate actual wave-function collapse..."

    2. Yes, it refers to decoherence. It is correct that decoherence does not collapse the wave-function. I didn't say it does.

  6. Paradoxes arise when the mental model with which we analyze a situation contains one or more elements that do not correspond to physically realizable situations in the physical universe. An example is asking what happens when an irresistible force encounters an immovable object, which requires the postulation of two entities for which there is no experimental evidence that they can exist. The paradox’s proper reconciliation recognizes that the properties of “irresistible” and “immobile” are both the organic equivalent of programs running in your neurons. This forces both to operate in resource-limited causal time rather than as “absolute” concepts in some more Platonic space in which hypothetically “perfect” concepts exist. The finite constraints of such execution mean that any attempt to compare them leads either to deadlock — which is the most accurate realization of the two programs’ logical incompatibility — or to the domination of one program over the other. The latter produces the apparent “paradox” of one of the claimed properties not meeting its specification.

    A reliable sign that you are getting into such a modeling paradox is when the model enters into an infinite loop, e.g., “it moves, it resists, it moves, it resists, …” or “I’m lying about lying, therefore I’m telling the truth, therefore I’m lying, …” The emergence of such infinite loops is a pretty good indicator that your model has assumed properties that do not correspond to physically realizable situations.

    So this leads to an interesting question: What, exactly, is an observer?

    If an observer is only a conscious being capable of self-examination, then the Wigner though problem unavoidably creates a modeling-level paradox loop by assuming two observers’ simultaneous dominance.

    An alternative definition of an observer that avoids modeling-level loop paradox is this: An observer is any unit of matter, typically thermal matter, whose internal complexity is sufficiently high to make time reversal of a wave function that becomes entangled with it statistically improbable, though never wholly impossible.

    The result, as is often the case with non-paradoxical modeling, more nuanced.

    Observation becomes a ubiquitous micro and nano process closely linked if not identical to entropy expansion. Wigner’s inside observer causes such a complex entanglement that her impact on the cat is utterly irreversible in the classical universe; the cat does indeed either live or die, quite regardless of the other observer. The result is a quantum isolated classical subsystem, which one could, I guess, call a hidden variable. But that oversimplifies the situation since the variable itself is no longer quantum, just isolated. The outside room, if mobile and isolated from the universe, could, for example, still be subject to diffraction through a cosmic double-slit experiment. But the cat would remain dead or alive even as the spaceship room interferes through both slits.

    I would note that this idea of classical internal variables within still-quantum units should be testable using diffraction of molecules large enough to self-collapse one or more internal states. Might be interesting.

    The other vital nuance in using micro-scale thermal observers — hmm, they need a name: Boltzmann observers, perhaps? — is that if you keep the number of states of the internal observer low enough, you can still reverse the death of the cat. It won’t happen with human observers, ever. But suppose you are using well-isolated sets of coherent photons. In that case, temporal reversibility can still happen, and the internal quantum state (e.g., of one of those large molecules) can remain quantum even as the outside state (e.g., of diffraction) becomes irreversibly complex (“observed”).

    As I said: Remove the paradox, and in its place, you get nuance.

    I have no idea how any of the above classifies in traditional terminology. I don’t care much since even inadvertent use of paradoxes tends to undermine the discussion’s semantics.

  7. In answer to the question in the video, I'd get rid of Superposition as it irks me.
    Dr Hossenfelder, I've read and watched some of your scientific explanations (but failed to grasp it due to lack of prerequisite knowledge) since I'm also intrigued by Superposition on an intellectiual level. I take it as given there's no reason to doubt your science, so no 'just wondering' from here.
    I've wanted to argue with you about it since I watched your video on Free Will, with respect (and awe. And the assumption I won't get to actually argue with you). Superdeterminism from your point of view seems to negate human religious faith, spirituality and searches for meaning in life; that's what irks me.
    On further reflection perhaps humans subconsciously are at the affect of Superdeterminism. the Christian view seems to sort-of agree insofar as God knows and can direct everthing that happens on Earth. Another manifestation might be people's desires to know and predict the future and the myriad methods devised by different cultures over time.
    I am quite interested in understanding fully so I'm going to look at the links you've provided.
    I'm interested in what others think about Superdeterminism too.

    1. Every quantum state is a superposition of something. I explained this in my earlier video. (Link's in post.)

    2. I mean, I watched your explanation of why there's no free will and was like, 'screw that!', so wanted to see what the underpinnings of it all are, but I don't understand much at a PhD. level. I need to take myself through everything from scratch; I've learned some from your earlier videos already - thank you.
      So I watched and listened to you presenting on the topic. I get that one needs a small, cold, quiet space to run experiments. That Elvis Presley was unlikely to be killed via poisoning by wormhole-travelling aliens, but even more unlikely to be hit by a bus. Then there's the Q&A, and seasoned physicists are asking questions. I'm sitting there like the proverbial 'stunned mullet', realising that you understand more about physics and the Universe than I'll probably ever know about anything (not to piss on what I do know).
      The implications of what I do understand are what I want to delve into, so I'll posit my philosophical ramblings to science-minded acquaintances on Facebook instead. I do think that 'Hossenfelder's Elvis' is a good subject for an explanatory video though.

    3. Postscript: I probably should've read 'Superdeterminism: A Guide for the Perplexed', it seems the best starting point.

    4. Dr Hossenfelder,I wrote 'superposition' instead of Superdeterminism, which was probably a predictive text fail. I just understood your reply. I feel a bit foolish.

    5. C Thompson,

      Thanks for the clarification, now your question makes much more sense...

      You write

      "Superdeterminism from your point of view seems to negate human religious faith, spirituality and searches for meaning in life; that's what irks me."

      Well, that's definitely not the case from my point of view, but it's arguably what most people think. Why they think so, I don't know.

      Look, for what free will and meaning and religion and so on is concerned, superdeterminism is no different from plain old determinism.

      The only thing different about superdeterminism is a specific type of correlation in systems where entanglement can get large, but that's not something we'd even notice in every day life for the same reason we don't normally notice entanglement. The effects are just too darn tiny.

    6. Dr Hossenfelder, thanks for elucidating your position. I used to be a Christian but became an atheist around mid-last decade. Christians hold that God gave people free will so they'd choose to follow Him but free will can't exist in Superdeterminism - I apologise if you didn't need me to tell you that.
      I have been thinking about what you've said from an ontological perspective (even though it's actually epistemic!) so I'm likely pretty off-track.
      Can I blame Superdeterminism for catching the wrong train this morning and getting to work late? (half-joking. I need to pay more attention).

    7. Free will doesn't make sense to begin with and it isn't compatible with determinism. As I said, this has nothing whatsoever to do with the "super" in superdeterminism. Also, lots of philosophers have tried to redefine will so that it is compatible with determinism. This compatibabilism works exactly the same way for superdeterminism. (Or doesn't work, depending on your perspective.)

      Yeah, that's a problem for Christians, but not a new one.

      We usually assign blame to something or someone if that entity was a major cause and we might come to the conclusion that something should be done about it. I have no idea what sense it makes to assign "blame" to a law of nature, unless by way of joking.

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    9. It is indeed absurd to blame a law of nature for my own actions, I may as well be upset that gravity exists.

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    11. (I deleted my comments because they didn't add anything worthwhile to the comments for this post)

    12. Dr Hossenfelder, I think I understand better what Superdeterminism is scientifically after going through others' blog posts and reading more. I appreciate you commenting to clarify for me.

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    1. Mr Tompson, greetings, I think you have made unnecessary extrapolations, for example, there are quantum equations for the interaction of an electron with another elementary particle; But when the electrons on the tip of my finger collide with the electrons in a hammer, they go straight into my mouth, skipping the whole theory. I mean, the initial object that produced the universe could not contain all the physical-mathematical equations to reproduce everything that we see including consciousness. You cannot skip the entire evolutionary process, until consciousness appears, free aldebrium does not appear.It's just my opinion.

    2. Luis, I'm Ms. Thompson, thanks. I'm still only toe-deep in all this. I was trying to describe something I understand at a basic level and reconcile that with my personal reaction and subsequent ideas, so there's likely several erroneous extrapolations in my thoughts. If I use the word 'fate' instead of Superdeterminism, then all the energy, particles, etc. from the beginning of the Universe are fated to create creatures that in turn have their fates set by the continued paths of all this energy and matter. We're fated to develop consciousness but can't access true free will and choices. This removes the need for any mathematical equations to reproduce anything, in my conception.
      I imagine physicists and people who know about physics might find my explanation ridiculous, but that's how I currently conceive of it.
      As for fingers and hammers, you're right, not much goes via our will.

  9. For what it's not worth, since you asked:

    Gravity was objected to as a form of spooky action at a distance when Newton proposed his theory of it. Einstein removed that objection with his theory in which gravity starts locally and spreads at the speed of light. So there seems to be some sort of valid physical intuition behind the objection. What worked in the past may not always work in new cases, but that is the way to bet, so I tend to accept 3, leaving the choice between 1 and 2.

    Which are tough choices for me. "Reality" certainly seems real, but so do a lot of things, like continuous motion in a movie. I understand that superdeterminism is not a conspiracy per se, and should be the subject of more carefully-controlled experiments, but off hand it seems difficult for choice of measurement settings to produce seemingly random quantum results over so many experiments over so long a time without anyone noticing any determinism.

    I also wonder if there could be combination effects of the three choices: a little unreality here, a little super-determinism there. That is well above my pay-grade though.

    What I would really prefer is a mixture of determinism and randomness. Is randomness what is meant by unreality? Just that fact that it is not deterministic, not completely controlled by past events? That is fine with me. Games with a bit of randomness--not too much--tend to be more fun than those without. Also, perhaps counter-intuitively, I have found some algorithms are more stabile and productive with a bit of randomness (usually but not always pseudo-randomness).

    1. The best explanation-of-sorts I can come up with is God/Laplace's Demon (not to be confused with Maxwell's Demon ;) ) has seen the whole thing through already in the future, so nothing's actually random from that viewpoint. As far as we the humans experiencing all this are concerned, it *is* random.
      My beef with Hossenfelder's superdeterminism is that it argues against us playing games and making choices etc., but the reconciliation I have is that there's a series of multiverses within which our other choices happen too, but that's been nixed too. 'Unreality' might just be an artifact of our squishy analogue brains, that we can come up with concepts that mash up and re-invent what we know of reality. But that's not random either, apparantly. Maybe we blank out the process of making deterministic calculations for our actions (as in playing games and in general life) so we don't seize up with a sense of pointlessness.
      It's all throwing me for a bit of a loop.

    2. "My beef with Hossenfelder's superdeterminism is that it argues against us playing games and making choices etc."

      CT, thanks for the reply.

      I don't think what Dr. H proposes actually does argue against us making choices. I would argue that determinism (including super-determinism) is what allows us to make choices that are not just random, but determined. That is, we can evaluate the options and choose the one that seems best based on our selection criteria. Without determinism, how could we do this? Without determinism, choices do not have any effect on future results--by definition.

      If there were such a thing as the effect of human will on reality (which there does not seem to be; we cannot will water to turn into wine), that would just be another determined property of our universe. There would still have to be a determined link between what we "will" and what happens as a result.

      Personally, in my experience, a little bit of randomness is actually a good way to run a universe. It means that if you are in a rut, there is a tiny chance you may find a way out of it (or in deeper) without any effect of your own choices. But without any determinism, I don't see how I could exist, much less make choices.

    3. I over-simplified. this is a better analogy: We can still set up a fun game, say a card game, but that event is pre-set in our timelines even as we organise the event. The cards may be shuffled and dealt at random but despite us thinking through how we play our hands, the outcome has already determined. We're having fun, but we're not cognizant of the fact we didn't, indeed could not, actually determine the course of the game itself.
      That doesn't mean it's not enjoyable.
      I don't think at all Dr. Hossenfelder believes Superdeterminism cancels out fun.

    4. Also, JimV, Hossenfelder Herself has commented on my comments above, so you can read some more of what she reckons. I also read back through some of her posts on 'no free will'. I like this one:

      I take it for granted that we live in a deterministic Universe and think even for any paranormal or psychic phenomena that there may be, there is some sort of practical explanation to be found but there isn't the
      I like my Universe to consist of random weirdness, joy, fun and Chaos - to me Chaos pulls everything together and sprinkles some randomness out there.

    5. Yes, if there is no randomness then given all the same conditions (including no memory of having made the same decision under the same conditions before) we make the decisions we were able to determine to make, but why should that bother you? A) there is no way to go back in time and make a different decision so worrying about it is meaningless; B) that is the price of doing business--if there were no determinism, no effects determined by causes, how could you make any decisions? Seriously, if effects aren't determined by all their causes, what is the alternative? Pure randomness, it seems to me.

      Jack Vance wrote a short story about that. The Earth passes into a "Negative Probability Zone" or some such thing, and all events become random. You could eat a piece of bread and have it turn into a stone in your stomach, or (if lucky) bite a stone and have it turn into bread in your mouth. You could take a step forwards and travel 1000 miles backward, and so on. That's what you get without determinism. I prefer determinism. (With a small amount of randomness.)

      You make your choices as best you can, and are responsible for them. If you make mistakes, you can learn from them and do better next time--thanks to determinism, you know that doing the same thing and expecting a different result is crazy.

      Free will has a good legal meaning, that you aren't being coerced or forced to make a decision you didn't want to make. That's all it is good for, as a concept.

    6. P.S. I don't actually have much of a problem with the religious concept of free will, because I can interpret it as meaning that we are entities which can make decisions, good or bad, whereas a rock can't. There are two (or more) requirements to make decisions: 1) determinism; 2) ability to do computations, which implies the ability to do logic computations. Evolution gave us the ability to do the latter, not a god, in my opinion, but we do have it. (For decisions to have any power, we need other capabilities also, such as senses and muscles.) Dogs have some decision-making capabilities also (about 500 million neurons worth, compared to our 70-100 billion).

    7. After reading more, seeing what Sabine thought of my comments, and thinking on the subject more, I tend to agree with your 2 last comments. Since I've become an atheist, I feel less disagreeable about other faiths/religious beliefs. People believe in all sorts of things. As I said above, the explanation for Christian free will is that God gave people that ability so that they can choose to put their faith in Him. In a previous blog post, Hossenfelder mentions in the comments that decisions can still be made, so I can accept decision-making ability is still present without free will, and given we think we're using free will, it may as well be. We can still learn from events and act on their consequences. And, we can create new art and appreciate what we sense. It's all part of what gives us experiences far beyond merely being alive.
      Without randomness or even pseudo-randomness, we'd be sentient machines. I enjoy watching sunrises, sunsets and rainbows, and conversations, etc, because each one is different from all the others.
      Lack of free will a la Hossenfelder was quite confronting to think about more closely, I felt my concept of self and what it means to have beliefs about life and the Universe in conflict with the implications of Superdeterminism, but I think I've resolved that conflict.
      That story sounds interesting, I'll try to track it down to read.

    8. C.T., thanks for your reply. I have enjoyed discussing issues here with you. I don't think we agree exactly on all the fine shades of meaning involved but that is okay with me. In a way, it illustrates that point that determinism does not mean we all move in lock-step in pre-determined courses. (We create those courses ourselves, using determinism to do so.)

      I have the Jack Vance anthology with that story somewhere within about 20 feet of me but that doesn't mean I could track it down easily, because it lies amidst about 3000 other books. Anyway, the most enjoyable way to find it will be to go to the library and read through the Jack Vance collection there, because even if you don't find it the effort will be enjoyable, in my opinion. I rarely laugh aloud while reading, but on the few occasions that happens it is usually due to a Jack Vance phrase. (The "Green Pearl" series is one of his best.) (Maybe your predilections won't be as good a fit with Jack Vance as mine, though. That's determinism for you--different causes lead to different effects.) Good luck (if there is any real randomness--on reflection, your simulated, chaotic randomness might work just as well, though.)

    9. I moved in December and I'm now unpacking and finding all the sci-fi books I'd bought and am yet to read, lol.
      I'm hoping to find a PDF online but I'll keep an eye out for Jack Vance books, sounds like an author I'll enjoy.
      I've been enjoying our discussion too. As for randomness within determinism, it occurred to me today that earlier this week I got to chat briefly online with one of my favourite music performers (who is also a renowned physicist) about religion and free will whilst hanging out on a science blog... not an experience I was expecting, lol.
      Have a good weekend.

  10. What I think being happened in measurements is a choice of antipodes. As measuring signals from opposite directions you cannot measure them both at the same time (you have to "choose" one or other) it's similar measuring entangled states - the spacetime conserves antipodes; measurement is the one or the other. When the furst guy measured the other can be only in the opposite state in the causal continuum of the initial conditions.

    1. Forgive me if this is a stupid question, but is this related to Heisenberg's Uncertainty Principle?

    2. Is quantum states related to spatial uncertainty in measurements based always ultimately on light-like interactions? That's a good question - any other good questions?

    3. Maybe when I finish reading 'Superdeterminism: A Guide for the Perplexed' :)

    4. @Dr Hossenfelder: Can you give us any answers please?

    5. C Thompson,

      The commenter by name "Eusa" has been here for quite a long time, and I generally cannot make sense of his or her comments. They tend to be polite and unobtrusive, so I usually approve them, but I am afraid I cannot help to unravel their meaning.

    6. I'm studying the planckian antipodal rhythm as spacetime "cellular" automata. Of course there is uncertainty present but imho the uncertainty is all about measurement. When we consider the measurement as part of phenomenon it's not correctly argumented that uncertainty have any physical meaning. Just like statistical quantum eigenstate is no physical until it's measured to be 100% observed.

      When we wonder what can be hidden variables i'm focusing the spacetime conserving entanglement info via antipodes - maybe as sort of distance parity.

    7. Eusa, thanks for explaining that.

  11. Dr. Hossenfelder;

    A topic after my own heart. If I may offer a thought experiment; Say we run ‘n’ number of particles through the double slits of the double slit experiment, measuring them in order to see what slit they go through and verify that they are acting as simple particles at the final screen. But with some n+1 particle the instant we measure the particle to determine which slit it went through, but before it can reach the final screen, we move the screen an infinite distance away or simply move the screen at some speed such that the particle cannot reach the final screen. Don’t these conditions create a situation where there is no longer a particle with a waveform traveling through the universe? We collapsed the wave at the double slit and then did not stop the particle.

    One step further, what if we make this now no waveform particle a neutron, which we know will most likely decay in around 10 minutes. Would this decay result in a virgin (no waveform) proton?

    As for which of the 3 choices I would rather give up, I do not believe that we have sufficient information to give up any of them. I believe there are far too many unanswered questions associated with the basics we already know. A quick example, there are so many unanswered questions associated with the standard model. Yet SUSY is going to increase the standard model three-fold. Doesn't this also increase the questions and complication three-fold rather than answer the initial question?

    Thanks Dr. Hossenfelder for making us all think.

  12. The state 'the cat is alive' means that the situation is such that in an arbitrarily large number of uniform experiments with exactly uniform cats, we will find cats alive. The 'cat is dead' state means that in an arbitrarily large number of uniform experiments with exactly the same cats, we will find cats dead. The superposition of the states 'cat is alive' and 'cat is dead' only means that the situation is such that in a sufficiently large number of uniform experiments with the same cats, we will find both dead and living cats. What is surprising in such a collapse of the wave function, I do not understand. In my opinion, this is a pseudo problem. Indeed, even if one cat in a box is found definitely alive while the entire system is in a superposition of the states 'alive' and 'dead', this does not disprove the fact of superposition of states, since one single case is not able to refute the statistics.

  13. Sabine, I heard somewhere that you plan to construct (and publish) a better superdeterministic model than the one you published with Sandro Donadi in "A Superdeterministic Toy Model". Any news on this?

    1. No, no news, sorry. Sandro is moving to a new job and my funding's running out. It's really difficult to do any research under such circumstances.

    2. Interesting. I would have though that Sandro's new job is at the Frankfurt Institute for Advanced Studies, and that it would make your research easier rather than more difficult.

      Funding ... of course it adds noise and stress to everything ... but in case it has negative effects it might also be related to missing trust. But it is easier to point to the money than to talk about disappointed or missing trust.

    3. That's his present job. He's leaving next month. I have no idea what your "trust" comment is referring to. If research funding was given out to researchers based on who can be trusted to deliver, both of us would be well off. But that's not how it works. To have a chance to get funding or a job, you have to work on something that's currently popular. That's how it works. And that's clearly not a criterion which superdeterminism scores highly on.

    4. Well, the "trust" comment was about my own experiences with the noise and stress related to founding. A positive example was the MAsk less lithoGraphy for IC manufacturing (MAGIC) EU project. During the project, IMS Nanofabrication AG demonstrated to project partners that it was a trustworthy company, with very open communication. So after the project ended, they continued with the partners whose trust they earned already, without additional EU (or other government) funding. Even before the end of the project, they did adjust their goal to a realistic target (a mask writer instead of a high throughput direct write system), demonstrating trust in the funding agency that it would not be held against them. Today, their multibeam mask writers found their place in leading edge semiconductor manufacturing.

      I was also thinking about negative examples, where funding was rejected. You do something else, no problem. Still it did hurt, but not because of the money. Part of what hurts is that you lose trust in the project. But part is also to admit that maybe the trust between the project partners was not high enough, and that you could have continued without the funding, if the trust would have been there.

    5. Of course we will try to continue the research, but I think you are missing the point. I have never had funding for myself for this research. I have been working on this in my free time, which doesn't work well for starters because not much of my time is free. My only collaborator will in the soon future move on to work on a different project just because he needs an income. This isn't going to help. You asked for news. The news is it's unlikely there'll be any news on this unless someone or some institution puts money into it. And let me be clear that I am NOT talking about money for myself. I'll be fine. This isn't the issue. The issue is that this research doesn't get done.

    6. Thanks for being open about the sad news. You are right that I thought you were talking about funding for yourself.
      Even with money, it will be hard to find someone who will construct the better superdetermistic model you and Sandro had in mind, because nobody else can really know what you two had in mind.

      I also dream of finding a model, but I don't care about whether it will be deterministic or local. What I have in mind is something along the lines of Jarek Duda's maximum entropy random walk or Arial Caticha's entropic dynamics (or even Wetterich's unfinished ...). The fascinating point for me is that accepting superdeterminism opens the prospect of finding an actual "low dimensional" model whose statistical behavior gets described by the mathematics of quantum mechanics.

    7. Hi Jakito,

      Thanks for your understanding. I actually think in the end it'll turn out to be some kind of entropy maximization principle. The question is "just" to find the right measure. I wish you good luck with your research,


    8. Why don't you apply for some funding from the Templeton Foundation, Dr. H.?
      It'd be more worthwhile if some of the money were diverted to your project and away from Luke Barnes' booming local pie shop.

      I mean think about it. They've given that numbhead over half a million dollars to play on his computer and eat pizza.

  14. According to superdeterminism, is the meassurement settings what determines the interference pattern in the doble slit experiment and in the delayed-choice quantum eraser?

    1. The measurement setting at the time of measurement, yes.

    2. David, the interference pattern is a consequence of the interaction between the incoming particle and the experimental setup (slitted barrier, screen, etc.). In the case of electrons or photons it will be an electromagnetic interaction.

      The EM interaction is long-ranged so it always takes place, not only when a "direct contact" is realized.

      Superdeterminism is a natural consequence of this fact. The instrument state is part of the experiment and it is to be expected to influence the outcome.

  15. Why is the cat not an observer?

    1. I think because it's the 'particle' in the experiment, and that there's nothing it can do to change the setup or how the experiment plays out.

    2. Or another way of looking at it is that the thought experiment is not concerned with what the cat observes but what an external observer observes.

      For instance, in the Many Worlds Interpretation, in some worlds the cat is alive and in some it is dead; the external observer is in those worlds also but doesn't know which one. The cat has no conundrum, if it is observing anything it is still alive. The external observer does. In some interpretations the position the external observer is in is considered a quantum superposition of different realities at the same time, and the math that was developed to predict quantum events implies that. However, there might be better math, yet to be developed, which could get the interpretation back to one reality at a time, which people might prefer. One might consider Dr. S's thought experiment as a challenge: don't like to think of the cat as a superposition of dead and alive? Then come up with a another theory that works better; or else stop worrying about it and accept the math for government work and assume there's a loophole somewhere.

  16. In the cat/box experiment, a process is defined that is comprised of multiple steps. If each of these steps has the potential of producing consequences to the observer, such as being poisoned when the poison was released or being killed by a massive amount of radiation when the radioactive trigger was activated then when the observer opens the box and sees the dead cat, the observer might reject the results of the experiment as unrealistic
    and invalid because the poison and the radiation effects have been dissipated when the box was in the state of superposition. In that state, the poison or the radiation cannot affect the observer.

    The observer must understand that any dissipative process that occurs and completes under the state of superposition does not impact reality. It is as if the poison and the radiation never existed. The only observed result of the experiment is the dead cat.

  17. Superdeterminism as a local hidden variable theory does seem to force us to abandon the idea that measurement outcome do objectively refer to the state of the natural world. If there are local HVs then we are forced to give up on the idea of objective measurements. Two observers, Wigner's friends who are observers that happen to obey the Schrodinger equation, can for an EPR pair report different outcomes to the outside observer who is "Wigner."

    I doubt it is at all decidable whether nature has a preference here. The superdeterminism may be something not that nature imposes, but rather what the analyst chooses.

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    2. The superdeterminism has the outcome entirely based on the set up. The problem is that the outcome(s) is or are ambiguous. The two Wigner friends report different results. This has the effect of at least weakening any definition of reality or objectivity.

      As I see it quantum interpretations have the effect of gathering the "dirt" of unknowing in different places. You can hide it here or there, but ultimately it is under some carpet. I sometime like Bohm's pilot wave analogue, where this is a sort of fluid. True to a fluid it is incompressible; squish it "here" and it squeezes out "there."

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    6. Sorry, all my above comments are inherently wrong on more than just stupidity level. Not sure why this question caught up and how to lead it to the closure now (keeps bugging!). So removed all that nonsense.

      The main import that I attempted to convey was that I didn't catch an inconsistency in QM and SD for combining states in particular. But that says nothing.

      Also checked Sabine's paper and it mentions:
      "Superdeterministic theories are not classical in any meaningful sense of the word. They can, and frequently do, employ the mathematical apparatus of quantum theory, as with states of the system being vectors in Hilbert spaces and observables being defined by hermitian operators acting on the states, some of which are non-commuting. Importantly, this means that superdeterministic theories can contain entangled states the same way that quantum mechanics does, and they also reproduce the uncertainty principle for conjugated variables."
      "...In particular, θ might describe the settings of multiple, spacially separated, detectors, as we commonly have in EPR-type experiments."

      But no further specific details about that. More of interesting excerpts.

      "Superdeterminism, therefore, is not an interpretation of quantum mechanics. It is a more fundamental description of nature, and Psi-epistemic not because it is non-realist, but because the wave-function (“Psi”) of quantum mechanics is an average description, hence epistemic and not ontic."

      "I have also repeatedly encountered physicists who either praise superdeterminism for being a realist interpretation of quantum mechanics or who belittle it for the same reason. As someone who is not a realist themselves, I am offended by both positions. Superdeterminism is an approach to scientific modeling. We use it to describe observations. (Or at least we try to.) Whether you believe that there is something called “reality” which truly is this way or another is irrelevant for the model’s scientific success.
      Realism is a philosophical stance. There is nothing in science itself that can tell you whether the mathematical structures in our models are real or whether they merely describe observations. It also doesn’t matter."

      "If one does not know the hidden variables, then one can merely make a probabilistic prediction based on the measurement settings. This probabilistic description is the one we normally get in quantum mechanics.
      It must be emphasized that λ is not necessarily a property of the prepared state. It is not even necessarily localized in any meaningful sense. It is really any kind of information that allows one to make a prediction. The term “hidden” merely means that these variables do not explicitly appear in standard quantum mechanics. There is no reason why these variables should be per se unmeasurable. In fact, since they determine the measurement outcome, one can use the measurement outcome to make inferences about the hidden variables, at least if they are computable."

      Ok, now it's reached some closure and I can relax :-)
      Have a nice day!

    7. Reality just means that what a measurement produces is a report on the state of a system. When the two friends make conflicting reports the is a violation of the reality principle.

    8. But that is so irrespective of the context. SD just describes the context (attempts to), or how the outcomes were received.
      It doesn't guarantee that the outcomes will be perfectly known, unless we can perfectly know the settings (and the rest). So, it's like shifting the perspective what to work with, or where to look for the 'dirt'. But I may not understand what you mean.

  18. Addendum: In my last comment, I asserted that if nano-scale “Boltzmann observers” exist, they should enable causal time flow and classical states within otherwise quantum systems. Such systems would maintain and evolve internal states even while temporarily isolated from the universe’s overall classical causality network.

    The most straightforward test for quantum-isolated time flows would be unstable molecules that display matter-wave interference even while reconfiguring internally. The reconfigurations would need to be sufficiently stable to qualify as classical and would need to occur without radiating photons that break quantum isolation. The decay rate would need to be consequential over the matter-wave travel time in the interferometer.

    Recent methods have demonstrated matter-wave interference for organic molecules containing thousands of atoms [1], making it likely that a molecule capable of such self-contained instabilities could be found or designed. The trick would be to use a sufficiently large molecule for these two states to appear as distinct classical states instead of as a quantum superposition.

    Stereoisomers, bonding isomers, and rotational isomers are possibilities. One of the simplest possibilities I can think of offhand (no numeric analysis) would be ethane with two substitutions on one carbon and one on the other, launched with the single substitution on the first atom nestled between the substitution pair on the other atom. Bulky substitution atoms would then favor decay by rotation of the single substitution ±120° to make it adjacent to only one of the pair on the other carbon. I am myself fond of Peierls instabilities in carbon loops — think of losing benzene bonding hybridization if the rings get too large — but those are likely too high in energy barriers and require unnecessarily large molecules to make classical.

    The goal is simple: Show that even if a molecule reconfigures itself classically while undergoing interferometry, it still interferes.

    [1] Fein, Y. Y.; Geyer, P.; Zwick, P.; Kiałka, F.; Pedalino, S.; Mayor, M.; Gerlich, S. & Arndt, M. Quantum superposition of molecules beyond 25 kDa. Nature Physics, 2019, 15, 1242-1245.

  19. OT: Sabine, I would be highly interested in a book review of "SHELL BEACH: The search for the final theory" by Jesper Møller Grimstrup. Also, I would be very eager to hear your comments on the Quantum Holonomy Theory, partly developed by the author.

    Keep up the great work, thanks for making physics understandable for the non-physicist!

    Best greetings from Rheinland, Jonas

  20. Well, I lean to superdeterminism. I see no physics evidence that rules it out and using some kind of argument from free will or other mental models just doesn't cut it for me. That's mixing levels of level of explanation really wildly. Superdeterminism just seems more likely to me in some way (aesthetic or metaphysical perhaps?) but I'm happy to be proved wrong with actual evidence. I think we need better basic physics to resolve this question so we will probably wondering what is behind the curtain for some time.

    1. I quite agree. Superdeterminism deserves far more funding for experiments than it presently gets.

  21. Sabine,determinism is not local.Chance is local. Free will is local.

  22. ... one of the following three assumptions must be wrong:

    1. No Superdeterminism.
    2. Measurements have definite outcomes.
    3. No spooky action at a distance.

    I find it acceptable if both 1. and 3. are wrong. However, I interpret "action at a distance" merely as "any nonlocal effect, including nonlocal randomness" and "Superdeterminism" merely as "violate Statistical Independence". So I don't insist on determinism. Not sure how Sabine intents those to be interpreted, especially since she wrote the following:

    A super deterministic theory is a hidden variables theory that solves the measurement problem and

    a) reproduces quantum mechanics on the average (“psi-epistemic”)
    b) is deterministic
    c) is local in the sense of not having “spooky action at a distance”

    It follows from this that the theory must violate Statistical Independence and be non-linear. (Need I say it follows that it reproduces quantum mechanics on the average?)

  23. And how would quantum physics describe the fact that the cat dies of a heart attack before the quantum effect that supposedly kills the cat occurs?

  24. Sabine,

    Schrodinger’s cat and Wigner’s friend thought experiments are based on the assumption that it is possible, in principle, to isolate a macroscopic object from the external world using some sort of a box. This is absurd, because such a box would effectively “delete” the inside from the universe. A charge placed inside would not interact with the outside charges and a mass placed inside would not interact with the outside masses. Such a box would violate the mass and charge conservation laws, so, without a fundamental change in the accepted laws of physics, it cannot exist.

    Let’s assume that a dead cat does not move, while a live cat does. There is no box that can stop you from detecting this by a measurement of cat’s gravitational field from outside. The only uncertainty regarding cat’s position/momentum is the one given by Heisenberg’s principle. The large mass of the cat makes the uncertainty practically 0. So, the cat cannot be isolated from outside, there is no uncertainty regarding what the cat is doing, hence no superposition. Box or no box, the state of the cat is an objective fact.

    The simple argument above shows that there will never be a superposition of macroscopic objects. It’s a fundamental limitation, not a technological one. The interference of large molecules is still based on the uncertainty relations, not on magical insulating boxes, so those experiments are not a counterexample for my argument.

    1. Andrei, hello, the trillions of particles that make up the Cat are what determine the fundamental state of the cat; even if he is totally isolated from the world; the carbon atom that is in a protein inside the nucleus of a cell of a hind paw of the cat is not at the same time in the paw or in the ear; It is trapped in a biomolecular system to which all the molecules of the system are subordinate, call that mutual interference or bound states or whatever, but the classical world is to be the final result of quantum physics, in other words, there is millions of known or unknown quantum equations in the system called cat, we do not know how to solve those equations; but we are sure that the end result is a cat and meow and the property called life belongs to a biological macrosystem; Right now you and I are being bombarded by tons of radiation from different sources and it does not cause our death; a quantum event by itself does not directly cause the death of anything; you need another organized macroscopic system to amplify it, which breaks the purity of the proposition.

    2. Luis,

      "Andrei, hello, the trillions of particles that make up the Cat are what determine the fundamental state of the cat; even if he is totally isolated from the world;"

      Can we stop here from a moment? Do you agree with my argument that it is impossible to isolate the cat from the world?

    3. Hello Andrei, I see the cat experiment in a didactic way, and from that point of view it is not very different from the particle that travels with two states that coexist and only when we observe it one of them is defined, but in the classical world those Two states exclude themselves, if I insist on imposing quantum reality in all its expression on classical reality, it would fall into contradictions.

    4. Luis,

      I think we need to be careful here. QM does not assert that a particle can have " two states that coexist". In general, QM does not make any claim in regards to what exist. As far as we know superposed states could represent just a mathematical way to arrive at correct predictions. The particle could still be in only one state, we just do not know that state.

      So, there is no explicit contradiction between classical and quantum physics.

    5. The main idea is the two friends obey schrodinger equation. The box just means their quantum states are coherent and unobserved until the box is opened.

    6. Lawrence Crowell,

      "The box just means their quantum states are coherent and unobserved until the box is opened."

      My argument above proves that such a box cannot possibly exist, their quantum states cannot remain unobserved so they will not obey schrodinger equation. It's as simple as that.

      All objects in the universe are "measured" continuously because of their long-range EM and gravitational interactions with each other. The only uncertainty is given by Heisenberg's principle. That means that you cannot put macroscopic objects like cats, humans or moons in superposed states that differ in any significant ways. Yes, you can have superposed cats that are different in position by some fraction of a Planck unit or so, as predicted by the uncertainty principle for such a big object, but this is all you will ever get. Live/dead cat superpositions cannot possibly be prepared, not even in principle.

      The Moon is there when you don't look, because your body feels its gravity. You measure the position of the Moon by simply existing in this universe and having a non-zero mass. The only way to not measure the Moon is to make its mass vanish. This cannot be done because mass/energy is conserved. Einstein was right. Bohr was wrong.

      A box that makes the mass inside vanish is an absurd concept. Cat/Wigner experiments are nonsense.

  25. Hello Sabine,

    I need about 2ms to drop 3rd, to delete the 3rd point.

    If I drop the 2nd point, then I can stop scientific work too.
    To me it sounds like this.

    Superdeterminism sounds to me like a rescue mission for locale thinking, for local theories. Hmm.
    When you look at the night sky, you see stars and planets.
    Since they are so far away, they appear to us as points.
    And they move continuously, not making jumps.
    With these two assumptions Newton (and Leibniz) could develop the
    differential and integral calculus.
    And with these again one can calculate very well the future position of the planets in the solar system.
    More than the position is also not necessary. A planet always remains a planet, it does not change for example its mass.
    One can explain this - I think - to a 12 year old boy or girl very well.

    In microphysics things are different.
    With the annihilation of electron and positron one has before two objects with
    - mass
    - electric charge
    - spin 1/2
    - a velocity v < c
    After the annihilation one has 2 or 3 photons with
    - no mass
    - no electric charge
    - spin 1
    - a velocity v = c
    And although everything changes here, we use a mathematics and a way of thinking, which was developed 350 years ago,
    to calculate the position of planets.

    That's why I prefere to drop the third point.

    In "catching light" you cite Einstein with his
    "striving for clear understanding".
    I like him too, but more this:
    "We cannot solve our problems with the same thinking we used when we created them."

    best regards

  26. Sabine: Do ya mean, that exactly one or at least one of the three statements must be wrong`?

  27. Addendum #2: Regarding candidate organic molecules for quantum-isolated classical causality experiments, please note that the rotational ethane substitution example is incomplete because it does not include a Boltzmann observer region.

    By definition, a Boltzmann observer region must have sufficient thermal-like configuration complexity to accept and statistically shred one component of an otherwise simple wave function, such as half of a phonon-mediated linear momentum pair. Without that, the system remains statistically reversible and thus quantum. A simple ethane substitution molecule such as C[H,Cl2]-C[H2,Cl] lacks such a region and remains quantum.

    I previously mentioned Peierls instability [1] in large polyacetylene rings (note that benzene is a 3-polyacetylene ring) because it is the most straightforward and best-analyzed molecular self-observing mechanism of which I am aware. The cumulative effects of lattice periodicity plus electron fermionic repulsion in momentum space create a statistical incentive for the electron band-charge concentrations to collapse into alternating charge densities that mimic the double bonds of simpler molecules. The resulting bond isomers (e.g., think of the two possible drawings of benzene without hybridization) then persist in a quite classical fashion. This is molecular self-observation, just by a different name! And it was beautifully quantified by the remarkable Peierls almost 90 years ago.

    Another approach to including a Boltzmann observer in a molecule is to add a side group with high configuration complexity and easy transitions between those configurations. Such a Boltzman observer group would then stabilize quantum states in other regions of the same molecule by almost-thermally shredding subsets of quantum number wave functions conveyed from those regions. Such observer groups must be messy enough to exhibit thermal-like complexity and close enough to interact by exchanging quantum numbers.

    Many biologically active proteins appear to possess such domains. Borgia et al. [2] note, for example, that “it has become increasingly clear that many proteins involved in cellular interactions are fully or partially unstructured under physiological conditions.”

    The existence of experimentally proven examples of built-in protein randomness raises an intriguing possibility: Are chemically active proteins such as enzymes configured to include Boltzmann observers? Such observer groups might help explain how enzymes convert reactants into new molecules via reaction paths that are otherwise astronomically unlikely.

    Perhaps the real trick in biology is not quantum computation but quantum observation. Enzymes enable desirable low-probability classical outcomes by first energetically encouraging those outcomes with their hand-and-glove template subregions. But more subtly, they may also then lock in that result by using a nearby Boltzmann observer region to shred less desirable quantum outcomes. The Boltzmann observer group would require some physical separation from the template groups since its randomness would otherwise disrupt the template. All that is needed is for the observer group to be close enough to “see” the reactants via one or more quantum numbers (e.g., phonon momentum) conveyed intra-molecule from the quantum reactants.

    If that is what is going on, Boltzmann observation likely plays a similar role in ribosomal protein folding. As long as the ribosomes are close enough to “watch over” the protein as it self-folds, they would behave as large, independent Boltzmann observers that help lock in the desired folding outcomes.


    [2] Borgia, A.; Borgia, M. B.; Bugge, K.; Kissling, V. M.; Heidarsson, P. O.; Fernandes, C. B.; Sottini, A.; Soranno, A.; Buholzer, K. J.; Nettels, D. & others. Extreme disorder in an ultrahigh-affinity protein complex. Nature, 2018.

  28. I would give up option 2. Measurements can have outcomes predicted by QM, before the measurement has been taken, but they are not assured to be accurate. The math is solid but the answer is variable.

  29. May one possibly be able to be aware of mental calculations one makes if one is aware of what processes underlie our ways of interacting with and reacting to people and circumstances to a higher degree than we usually engage in, thus getting glimpses of our brains making calculations? I've done a fair few personal development courses delving into the machinery/programming that drives us, and how to act and react more effectively with improved self-awareness.

  30. Researching super-determinism seems impossible if super-determinism were true.

    1. I wouldn't go that far, however I find it pretty bizarre that the person telling us this also doesn't have free will nor access to the inner workings of their own neurons, but they've managed to work Superdeterminism out and here we are. :)


      Superdeterminism is a type of physical theory where certain objects that we happen to call "sources" and "detectors" have correlated states.

      Physics is full of examples where different objects have correlated states. Orbiting stars have correlated states, planets in a planetary system have correlated states, stars in a galaxy have correlated states, electrons in an atom have correlated states, synchronized clocks have correlated states. There is nothing peculiar about it. Such correlations are caused by long-ranged interactions between those objects.

      Particle sources and particle detectors are made of charged, massive particles so one would expect, given the laws of physics we have (gravity and electromagnetism), some degree of correlation between their states.

      There is nothing impossible about studying the degree of correlation between the states of such objects. It has been done for other systems before.

  31. Thanks for the shout out to Calgary!!
    Our city is between the prairies and the Rocky Mountains.
    I've always felt it is a Super Position to be in!

  32. I need someone to explain this to me- in the EPR experiment when the spin of a particle is measured, the other is inverted, it is said the two states coexist until it is measured, however, the same happens with the electric charge, I do not see if it is a positron or an electron until I measure it; but I don't know anyone who says that the particle is positron and electron at the same time until it is measured. It seems to me that the two properties are self-exclusive just like the dead cat and the live cat. It seems that the whole universe, including the space that surrounds the particles, knows which is positron and which is electron.

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    2. Jay10:36 AM, March 03, 2021

      And superdeterminism allows the possibility of compelled, infrequent sapient life, thus trivially refuting SAP.

      A trivial refutation that you won't accept because you are a liar.

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    5. Jay,

      What comment? Steven's? What's he done now, called you a liar? Steven, come here, apologize to Jay. Now please play nicely.

    6. Jay10:24 PM, March 03, 2021

      You stated very clearly that if infrequent sapient life is observed then it follows that life is not compelled to exist in a homogeneous universe. But that is not necessarily the case as infrequent sapient life could be observed in a superdeterministic universe based on current empirical evidence. Every single event is "compelled" to happen in a superdeterministic universe, so to suggest there is some question mark as to whether we can consider infrequent sapient life to have been compelled in a superdeterministic universe is, a fortiori, nonsense.

      You are trying to deny that synonymous terms are synonymous.

      You also stated very clearly that you are the kind of person who admits when you are wrong, and suggested that though I considered myself to be such a person I was possibly deluding myself.

      And yet, here we are. You have been proved wrong trivially, and instead of admitting you are wrong, you are trying to suggest that if something is superdetermined it may not be compelled.

      Thus,you have been proven trivially wrong and a liar.

      It is not an insult, it is a fact. You are a liar.

    7. Jay1:13 PM, March 03, 2021

      "@SH, is that the kind of comment you want on your blog?"

      No,Dr. H, wants the blog comments filled with lies from people like you.
      Explain how life being superdetermined to happen does not constitute life being "compelled" to happen (Christ, what nonsense we get dragged into discussing when talking to people who have studied some "philosophy") or apologise for your lies like an adult and then we can move on.

    8. Steven,

      I don't think most of these people are deliberately lying. They have just managed to convince themselves of something that's internally inconsistent and don't notice. The accusation of lying assumes an intent of deceit and I don't think that's what's going on, so I think it would be appropriate if you could tone it down a little.

    9. Sabine Hossenfelder3:37 AM, March 04, 2021

      Dr. H., you know as well as I do Jay would rather lie about seeing a distinction between "compelled" life and "superdetermined" life than admit he is trivially wrong. And now he cries to teacher about how his delicate sensibilities have been hurt at accusations of lying? That itself is a dishonest stance.

      If people don't want to be accused of being liars they shouldn't lie. Jay is over 12 years old. He needs to learn to admit when he's wrong. You've done it on here. I've done it. Now it's Jay's time to be an adult.

    10. Luis,

      "in the EPR experiment when the spin of a particle is measured, the other is inverted, it is said the two states coexist until it is measured"

      Some physicists say that, some do not. However, if one wants to have a local theory one needs to accept that the particles' spins have been decided at the time of emission. If particle A was measured as spin up on Z, it was spin up on Z even before measurement, while the particle B was spin down on Z even before measurement.

      If you want the particles to be in a mixtures of states, whatever that might mean, you need a non-local (instantaneous) signal traveling from one detector to the other. Without such a signal there is no way to reproduce the experimentally observed perfect anticorrelation.

      For some reason most physicists to not grasp this simple argument and continue to make the false claim that a fundamental indeterminism can save locality. In fact it's exactly the opposite. Only determinism can save locality.

      So, if you want locality, which is an established principle of physics, you need to interpret superpositions as reflecting our uncertainty in regards to the true, objective state of the particles, not as a real combination of incompatible states. The cat is either dead or alive, the charge is either positive or negative and the spin is either up or down.

    11. Hi Andrei, my question is why the same question is not asked about the electric charge in the same experiment?

    12. Luis,

      To be honest I didn't hear about experiments with electron-positron pairs being done. It's not easy to prepare such pairs. Can you provide some context here? Who is not asking about electric charge? What experiment are we speaking about?

    13. Hello Luis,
      In electron positron pair creation, one gets an electron and a positron from birth. This can be seen by the rotation of the spiral with a vertical magnetic field.
      But with two entangled photons the polarization is undetermined until the measurement. And this can be many km away from the point of creation.
      The same happens for particles and spin.
      Many greetings Stefan

    14. Stefan Freundt,

      "with two entangled photons the polarization is undetermined until the measurement"

      If physics is local it has to be determined since the emission, prior to measurement, as the EPR argument proves.

      Sure, you might have undetermined polarizations and have a real, non-local collapse "create" the correlated outcomes but it is by no means the most reasonable interpretation. Locality is pretty well established at both theoretical and experimental level.


    15. ok Stefan, a gamma quantum decomposes into a positron and an electron, if you measure the spin of the electron and it is upwards, then that of the positron is downwards, or vice versa, that's what they say, they also say that until it is not make the measurement the orientation of the spin is not known and also the two orientations are linked; But the same thing happens with the electric charge, it is not known what it is until it interacts with the meter, but nobody believes that the electric charge is undefined until it is measured, it is assumed that it is given from the moment it decomposes .

    16. As I vaguely understand it, the force due to charge is due to the emission and absorption of photons, so charged particles are interacting with other charged particles constantly (trading photons), which I suppose acts as a measurement (of charge polarity).

      We don't really know if gravitons exist or in what frequency they are emitted and absorbed if they do exist, or what information aside from mass they might transfer, so it is not clear (to me, at least) that they could act as measurements in the same way.

    17. Luis,
      electric charge interacts with photons and because there are photons everywhere, there is also immediately an interaction and therefore a measurement. So it is determined right at the beginning who is electron and who is positron.

    18. Andrei,
      interesting argumentation. You say something like, "Because local theories have proven themselves in the macroscopic world it is good to apply this way of thinking to the microscopic world as well."
      If the polarization of entangled photons is already fixed at emission, then you need superdeterminism.
      (Sabine - correct me if I am wrong at this point).
      I don't like superdeterminism. In my opinion, superdeterminism is too complicated for the objects.
      That's why I prefer "non-local" thinking and spooky remote action.
      I am well aware of the difficulties with remote action.
      By the way: for me the main question is: how to create objects that are stable and flexible at the same time....

    19. HiStefan, then if the electric charge is always determined, and the charge in turn is an important part of that framework that makes up the whole system called cat; Why is the quantum state more determining than the electric charge in the state of the cat ?; That is, can I take a quantum condition of a particle to subordinate a whole system of trillions of particles to this, overlooking all the energy and dynamics of the system itself? My position is that there is a limit to do that, after that limit enters to dominate other properties; so the propositions must be within those limits; Otherwise, you could take a nervous function of an ant and determine with it all human behavior, or, skip all evolution and "give birth" directly from the big bang a human brain

    20. The thought experiment postulates that radioactive decay, or some other phenomenon involving a single atom, triggers the device which kills the cat. So that quantum superposition of that single quantum event results in a macroscopic superposition. (Nobody is saying the cat disappears, all its particles are still there, but either alive or dead.)

    21. Hello Luis,

      I probably don't really understand your question very well.
      But I can tell you some little stories.
      Then know how I resolve all the weirdness of quantum mechanics
      and with some luck it will answer your question.

      1. Logic
      Many years ago I attended a school with extended mathematics classes.
      In the 9th grade we had logic. For half a year we had logic.
      It was boring. There is nothing more boring than mathematical logic.
      There is one point that is interesting:
      It is possible to start with wrong assumptions and after absolutely correct transformations you get a correct, true result.

      2. Our planetary system
      Some years ago scientists were convinced
      the earth would be in the center of the world and everything would
      revolve around the earth. If you spend some time observing the night sky with the naked eye, you can confirm this. you can confirm this. For example the Mars stands after about 2 years again at the same position - compared with the fixed stars.
      This idea of the world is easy to convey and agrees well with the observations.
      That is why scientists followed it for about 1500 years.
      All difficulties could be solved quickly.
      For example, Mars slows down its movement around the Earth,
      then moves in the opposite direction for a few weeks,
      to stop again and move back in the original direction.
      You can find very nice pictures on the internet with the keyword "retrograde Mars".
      1000 years ago a student may have asked why Mars changes its motion.
      Well, the answer is simple, "Angels keep Mars on its orbit with their flapping wings."

      Well, since Copernicus, we know better. Everything revolves around the sun.
      The retrograde motion of Mars is an illusory motion.
      And the student's question simply disappears, the question decays.

      3. Micro physics
      Modern physics with quantum theory always reminds me of the Ptolemaic planetary system (see above).
      One can calculate many things with impressive accuracy.
      But one cannot say how the objects make this happen.
      At that time one could not answer why Mars is retrograde for some weeks.
      And today one cannot answer many questions of quantum mechanics.
      Or in short:
      Microphysics is a feast for engineers
      and a nightmare for scientists.

      For me quantum mechanics is so suitable to understand small objects,
      as the Ptolemaic world system is for the motion of the planets.

      Everything depends on a better theory.

      Many greetings

    22. Ok Stefan, I'm going to put it this way; suppose that instead of releasing a poison, the system releases the virus Covid 19, in what state is the cat now? He may have Covid and not die and even not have it and die from the stress caused by being locked in the box. I mean, the system called Cat and Poisoning Device is more complex than a binary quantum system; I accept that until the first stage, before there is amplification, there is a correlation with the quantum phenomenon; but after that the system has a very complex evolution, and there is not even another quantum process that can reverse it or return it to the initial state. You say, why so careful? , if the classical world comes from the quantum; so this experiment instead of explaining it distorts it

  33. It's embarrassing and depressing that Schrödinger's infamous cat is still causing debates. For Schrödinger the idea of a cat that is both dead and alive was clearly ridiculous. Unfortunately he didn't carry this reductio ad absurdum to its logical conclusion. He just couldn't give up the idea that his time-dependent equation was the full story, and that the wave function describes an individual system. (Interestingly the cat paradox arose from correspondence with Einstein, who favoured a statistical interpretation.)

    The wave function acquires physical meaning for example in the theory of the Josephson effect, where it describes the collective behaviour of Cooper pairs. (See the last chapter of the Feynman lectures.) Or in superfluid helium. Or in the more familiar context of a beam of polarized light. The Stokes parameters describe correlations between the electric field components, and it is just a manner of speaking to confer these statistical regularities to individual "photons". It is for a reason that the orthodox interpretation insists that the polarization of a photon is undefined until measured. The essence of a tsunami is not expressed in a molecule of water.

    > "One especially peculiar aspect of quantum mechanics is that it forces you to accept the existence of superpositions."

    > "We know this experimentally."

    Not only quantum theory requires interpretation. Experiments even more so. You ought to step back far enough to see that many implicit assumptions are made already in describing the experiments, when we talk about "quantum systems" having "properties"or not (or only in "uncertain" ways). That the double slit experiment "proves" that an electron passes through both slits is an over-interpretation. Bohmian mechanics provides a counter-example.

    Regarding the three hypotheses of which one must be given up, I would add that there are many more that were left out and left implicit. But if you are interested in my position, I'd choose no. 3 ("No spooky action at a distance") as the easiest one to give up. Although action needn't be spooky if you allow particles/waves to travel backwards as well as forwards in time (as is the case in QFT).

    1. A part of what causes people to go into fits is that in quantum mechanics the logical operations AND and OR are not distributive. They do not obey the distributive property of Boolean logic. So while a cat may be alive and dead this AND is a quantum form of AND. The fate of the cat is equivalently alive or dead, for OR a classical meaning of OR.

  34. Since it is aphoristically well known that a cat has 9 lives, why is Schrodinger's cat even interesting?

    1. Chris, what about the superposition of dead/alive states? Chris, it's interesting because it's thought-provoking, and raises interesting questions as people encounter it. If the cat has 9 lives, does the pre-unboxing superposition of dead/alive states use up one or two lives at once, therefore rendering a cat useless after four or five iterations of the experiment?

    2. Ignore second 'Chris', I didn't catch that before posting.

  35. A new way to have fun at parties: tell people "Free Will doesn't exist!", attempt to explain why, then watch people's heads explode.

  36. Random thought: Could 'spooky action at a distance' possibly come from particles being correlated together superdeterministically during the Big Bang or afterwards?

  37. Andrei,

    That correlation better be 100%. Else what's the point of superdeterminism? And if all two objects are 100% correlated, then everything is 100% correlated including the researcher and the test equipment. Hence the impossibility of research.

    1. Nonlin.org1:50 AM, March 05, 2021

      How do you know research that uncovers the superdeterministic nature of the universe cannot be superdetermined? I fail to follow your logic. Maybe physicists were bound to happen, like gravity.


    "That correlation better be 100%"


    " if all two objects are 100% correlated..."

    Correlations exist between certain physical parameters. The accelerations of 2 orbiting stars are 100% correlated (they point to their common center of mass) but their emission spectra could be completely uncorrelated. So, it's not that everything is 100% correlated, but some physical quantities are.

    Let's make a more detailed analysis. All objects involved in an EPR/Bell test are ultimately just groups of charged, massive particles (electrons and nuclei). All those particles interact according to the laws of electromagnetism and general relativity. The simple fact that they have to obey those laws means that the evolution is not random. If the laws of EM and gravity are fundamentally deterministic (as the classical theories are) it follows that the motion of those particles is 100% correlated to each other in the sense that no particle could move differently than it does.

    Now, we do not observe, nor can we observe (because of the uncertainty principle) the individual motion of those particles. Even if we could, we could not solve all those equations for 10^26 particles or so, so it's practically impossible to observe those correlations at the microscopic level. What we can observe is the macroscopic behavior, which is an emergent, statistical one.

    In order to test superdeterminism one should come up with a correct statistical treatment of the experiment. This has never been done. Bell theorem simply assumes that the microscopic correlations cancel out at the macroscopic level. That's an unproven hypothesis and there is no reason to take it seriously.

    In conclusion there is nothing peculiar about superdeterminism. It's just the correct way of analyzing an experiment. If you notice some macroscopic correlations you need to investigate their origin in terms of the known laws of physics at microscopic level. Nobody is doing that.

  39. Classical determinism is dead. QM killed it. If you disagree, here's the experiment that proves it: we have a double slit experiment with single photon emissions and the target area separated in 10 different sections labeled 0 to 9. Once a section is hit, it stays on (cannot detect multiple hits) Determine the output sequence? Is it 017...9? Is it 875...6? What is it?

    Given this, superdeterminism seems to me just a doubling down on that which was disproven. And, if microscopic correlations do not cancel out at the macroscopic level, then that's exactly my point. Setup and researcher are caught up in the same network of perfect correlations. Basically, everything is preordained, in which case no research is possible. Come to think of it, that was the case with classical determinism as well.

    If you disagree, you should start by explaining what's different in superdeterminism from the old determinism.


      "Classical determinism is dead. QM killed it."

      This is false.

      "If you disagree, here's the experiment that proves it: we have a double slit experiment with single photon emissions and the target area separated in 10 different sections labeled 0 to 9. Once a section is hit, it stays on (cannot detect multiple hits) Determine the output sequence? Is it 017...9? Is it 875...6? What is it? "

      Give me the position, momenta, EM field configuration and charge distribution for the source, slitted barrier and screen and a computer good enough to solve the corresponding equations of a 10^26 body system and I'll give you the prediction you want.

      Determinism implies that IF you know the initial state and the laws governing the system you could predict the state in the future. In practice we do not know the initial state, we may not know the fundamental laws describing the system (we have no consistent theory of EM classical or quantum) and we have no way to perform the calculations.

      Your experiment proves nothing.

      "Basically, everything is preordained, in which case no research is possible."

      Why? I see no contradiction between determinism and reason. In fact, reason presupposes determinism.

      "If you disagree, you should start by explaining what's different in superdeterminism from the old determinism."

      Superdeterminism is a particular type of determinism. And determinism is perfectly compatible with the ability to make research.

    2. The idea that research isn't possible if the laws of nature are deterministic is complete rubbish. The idea that you can "disprove" determinism because you were not able to predict a sequence of numbers is likewise nonsense. Both of these statements are trivially wrong, document that you have not thought much about the matter and have never bothered to look at the relevant literature.

    3. It's not that I or someone else cannot predict that outcome, but that the outcome is FUNDAMENTALLY undetermined even with an ideal computer. Where the next photon hits is unknowable except statistically.

      You say: "Give me the position, momenta, EM field configuration and charge distribution for the source, slitted barrier and screen and a computer good enough to solve the corresponding equations of a 10^26 body system and I'll give you the prediction you want."

      How? What about the uncertainty principle? And as much as you control the inputs, the interference pattern remains the same. This is totally different than the deterministic systems (hereby invalidated!) where the normal distribution of outputs can be narrowed by tightening the inputs / set-up with the theoretical conclusion that perfect inputs / set-up will result in perfect outputs (determinism).

      Determinism doesn't mean that output is SOMEWHAT determined by inputs (reason is possible) but that output is 100% determined by inputs (reason is impossible).

      You say: "Superdeterminism is a particular type of determinism."

      This is not an explanation.

      Sabine, can you link to the "relevant literature" that you claim unambiguously disproves my points? I can’t find any.

    4. "It's not that I or someone else cannot predict that outcome, but that the outcome is FUNDAMENTALLY undetermined even with an ideal computer."

      That's the case in standard quantum mechanics, yes. But you missed my point. I was saying you'll not ever be able to figure out whether it's indeed fundamentally random or whether you just were not able to make the correct predictions because you had the wrong theory.

      "Sabine, can you link to the "relevant literature" that you claim unambiguously disproves my points? I can’t find any."

      Your "argument" is trivially wrong. No one would bother writing a paper to spell out that you can't prove something is fundamentally random.

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      "It's not that I or someone else cannot predict that outcome, but that the outcome is FUNDAMENTALLY undetermined even with an ideal computer."

      You assert that the outcome is "FUNDAMENTALLY undetermined". Assertion does not equal proof. In your previous post you claimed to have a proof. I don't see it.

      "Where the next photon hits is unknowable except statistically."

      It might be unknowable but this does not mean is not deterministic. If the initial state is unknowable so it is the final one, even if the system evolves deterministically.

      "What about the uncertainty principle?"

      Well, that's your problem. You cannot ask me to predict the outcome without giving me the initial state.

      "And as much as you control the inputs, the interference pattern remains the same."

      I think I would disagree here. If the incoming particles are perfectly focused on slit A no interference would be observed.

      "This is totally different than the deterministic systems (hereby invalidated!) where the normal distribution of outputs can be narrowed by tightening the inputs / set-up with the theoretical conclusion that perfect inputs / set-up will result in perfect outputs (determinism)."

      Nonsense. You do not control the charged particles in the barrier, so you do not control the EM fields acting on the incoming electron. If you shoot bullets toward a forest moving in the wind you will not be able to predict if the bullet will hit a branch just by increasing the accuracy of the rifle. You need to know where the branches are when the bullet is shot. Likewise, in order to calculate the trajectory of the electron you need to know the EM fields (produced by the electrons and nuclei in the barrier) acting on it.

      "Determinism doesn't mean that output is SOMEWHAT determined by inputs (reason is possible) but that output is 100% determined by inputs (reason is impossible)."

      Except from the "reason" part I agree. Determinism implies that for any initial state the evolution is unique.

      "You say: "Superdeterminism is a particular type of determinism."

      This is not an explanation."

      Superdeterminism is only defined in relation to Bell tests. A superdetermintic theory implies a correlation between the hidden variable and the states of the detectors. It has nothing to do with ones' ability to reason. Reason does not depend on Bell tests.

  40. As I have committed previously, without some determinism, research or any kind of reasoned process would be impossible, since the opposite of determinism is pure randomness in which coherent thought itself would be impossible. That seems ironclad to me. Saying that determinism makes research impossible would then rule out any possibility of research. This is not true, in my opinion.

    Research is a search process, an elimination of the impossible, or what doesn't work, until what works is found. (Edison famously remarked that he had discovered about ten thousand things that did not work.) If a solution exists, and you search long enough without going in circles, you will find it. Nothing about determinism rules that out.

    I also think there may be a logical fallacy lurking in the concept that under determinism, everything is preordained, having to do with the semantics of ordainment. It has the semantics of compulsion, forcing things to be done in a certain way regardless of the input of those involved. In fact, under determinism we are largely doing what we want to do, following our natures, making choices without necessarily feeling any compulsion. Only in hindsight, when it is too late to change the past, can we say what we did was bound to happen. It seems to me just as true to say that we choose our actions in the present moment, rather than that they were chosen for us by initial conditions at the Big Bang.The result turns out the same either way, but I for one see myself making deterministic choices (as best I can) rather than acting as a puppet, and learning from my mistakes. With that attitude, at least, we can do research and make progress.

    At the end of a long ride, horses head for the barn without compulsion, knowing hay and oats are there, not with a feeling of preordainment.

    1. JimV, I give this comment a 'like'. there's a novel, 'Traveller In Black' by John Brunner, that describes a realm that's in the clutches of chaos and operates in pre-science, beings and events are magical and consequences bizarre, and the Traveller helps to bring this realm to a more stable state that resembles our world. To agree with your previous words, Determinism gives us a sensible world we can operate efficietly in.

  41. Regarding: "Schrödinger's Cat: Still Not Dead"

    The certainty that both hidden processes and variables can exist under the state of superposition in a way that these hidden processes and variables cannot be observed in the real world opens up the possibility that inside the box the laws of nature are different than those that exist outside the box. The state of that voluum of space inside the box can be completely disconnected from the world outside the box.

    Yet the universe that develops inside the box can impose permanent consequences within our reality when the state of superposition inside the box eventually terminates but the transient effects that have occured in the universe of the box effectively did not occur.

    The situation that I am interested in is the development of negative energy inside a state of superposition. This situation is represented by the development of negative energy inside the box that has appeared as a hidden variable. As a hidden variable, any process catalyzed by it would not be observable while the process was ongoing and when the box was opened the unobservable process would terminate, but the permanent effects that this hidden variable had on the cat would still be realized upon observation.

    It is now accepted by science that the development of negative energy in our universe would start a destructive process called the Higgs catastrophe. But this universe ending process does not apply if the development of negative energy occurs under a state of superposition.

    In total, this set of hidden and actualized causes and effects leads to the results of negative energy appearing in the universe yet not the realization and the recognition of negative energy itself.

  42. The Exotic Vacuum Object (EVO) is a bubble of Anti-de Sitter space (AdS space) that is formed through the condensation of tachyons made available within a superconducting seeded environment. Inside the bubble of AdS space (EVO), there exists another universe that is incompatible with our universe (De Sitter space)

    When matter in our universe encounters AdS space inside the EVO, it decomposes into pure energy. Most of this energy is lost through a superposition effect produced by superconductivity of the tachyon condensate. But some survive the termination of the EVO to produce newly formed elements that form in De Sitter space from this excess energy residue. This we call transmutation of elements.

    In more detail, at the center of the EVO there exists a black string which is a zone of nothingness. It is this core that deconstructs matter from De Sitter space that enters the zone of nothingness into pure energy.

    In a recent paper - Nothing really matters

    Our unstable universe is described, but the process of total matter destruction throughout the universe as described in the paper is not totally correct as we have found through our recent experimentation with EVOs (these bubbles of nothing). The process of distruction does not seem to spread from the EVO into De Sitter space. Fortunately, the zone of nothing seems to remain confined within the bubble of Anti-de Sitter space.

    Sometimes superposition does not immediately set in for a second or two and a lot of subatomic particles and gamma radiation is produced. But when the engineering is right, this disruptive and unpleasant process is eliminated.

  43. Would a universe that's random cool down faster than one that's deterministic?

  44. Regarding: The characterization of the Bosenova as follows:

    "A bosenova is a very small, supernova-like explosion, which can be induced in a Bose–Einstein condensate (BEC) by changing the magnetic field in which the BEC is located, so that the BEC quantum wavefunction's self-interaction becomes attractive.

    In the particular experiment when a bosenova was first detected, this procedure caused the BEC to implode and shrink beyond detection, and then suddenly explode. In this explosion, about half of the atoms in the condensate seem to have disappeared from the experiment altogether, remaining undetected either in the cold particle remnants or in the expanding gas cloud produced.

    Under current quantum theory, this characteristic of Bose–Einstein condensate remains unexplained, because the energy state of an atom near absolute zero appears to be insufficient to cause the observed implosion. However, subsequent mean-field theories have been proposed to explain the phenomenon.

    Although the total energy of the explosion is very small, it appears very similar to a tiny supernova, hence the term 'bosenova'"

    I posit that those missing atoms disappear without a trace because the Bose condensate is still coherent when the condensate explodes and it is superposition that causes the atoms to vanish to some unknown place outside of our current reality.

    1. What might happen with them there?

    2. They might be teleported to another place and another time.

  45. "That's the case in standard quantum mechanics, yes. But you missed my point. I was saying you'll not ever be able to figure out whether it's indeed fundamentally random or whether you just were not able to make the correct predictions because you had the wrong theory."

    Yes, one cannot prove a negative. Then what about free-will-is-dead-lets-bury-it post? Furthermore, on the here and now basis, determinism is experimentally incorrect as the double slit shows. Let’s bury it! I will personally unbury determinism when we’ll have the right theory.

    “If the initial state is unknowable so it is the final one, even if the system evolves deterministically.”

    “If the incoming particles are perfectly focused on slit A no interference would be observed.”

    That’s not it. QM is fundamentally different than classical mechanics.

    “If you shoot bullets toward a forest moving in the wind you will not be able to predict if the bullet will hit a branch just by increasing the accuracy of the rifle. “

    Not what I said. Read again. Fact: in classical mechanics you WILL increase the accuracy of the output if you increase the accuracy of any of the independent inputs. As long as the rifle is independent of the wind, increasing the rifle’s accuracy does absolutely improve the accuracy of the shot. Even if dwarfed by the wind input.

    “Superdeterminism is only defined in relation to Bell tests. A superdetermintic theory implies a correlation between the hidden variable and the states of the detectors.”

    Bell test tells us about the nature of the universe so, if true, there’s nothing limited about superdeterminism. “Hidden variables” are not science. Not yet at least.

    1. "Yes, one cannot prove a negative. Then what about free-will-is-dead-lets-bury-it post? "

      As I have repeated a seemingly endless number of times, my arguments are always based on science "for all we currently know". For all we currently know, free will doesn't exist. It's a statement about the currently accepted laws of nature, no more and not less.

      "Bell test tells us about the nature of the universe so, if true, there’s nothing limited about superdeterminism."

      Superdeterminism is a modification (or, you may say, completion) of quantum mechanics that replaces the wave-function collapse with a physical process. These effects are obviously limited to the cases where we now think a wave-function collapse happens. Bell tests tell us about systems on which you can do Bell tests.

    2. Sorry to insist:
      Nothing in the "for all we currently know" forbids free will. Not when you stop presupposing determinism.
      Something in the "for all we currently know" (the experiment I propose) invalidates determinism. There is no way anyone can forecast - even theoretically - the number sequence. Again, "for all we currently know".

      As far as Bells test, a wave-function collapse seems to be happening all the time and everywhere. You might want to consider a post on superdeterminism explaining its assumptions, reach, and limitations.

    3. "There is no way anyone can forecast - even theoretically - the number sequence. Again, "for all we currently know"."

      Right, but as I have explained countless times, if it's random it's no will. Atoms decay randomly but we don't assign them free will because of this, do we?

      Look, this isn't a new argument. Free will is a logically incoherent idea. You can't have it both ways, either it's not free or it's not a will. Or, as Nietzsche put it "the best self-contradiction that has been conceived so far".

    4. You don't know that atom decay is 100% random. You just know that it's not forecastable, hence not determinism "for all we currently know". That tells you absolutely nothing about free will.

      Regarding "logically incoherent idea" and Nietzsche, that is pure philosophy of the unscientific kind. Which of course anyone is entitled to. Let's just be clear that said argument has nothing to do with science or the scientific method.


      That it's not deterministic for all we currently know is exactly what I am saying, thank you. But you are missing the point, free will would be an inconsistent and meaningless idea whether it's deterministic or not. Nietzsche's argument is unscientific insofar as that it doesn't depend on the science, but that only makes it a stronger argument.

    6. As far as we know, there is either determinism (cause and effect) or randomness, or some combination. If "free will" is meant to suggest that there is a third way for things to happen, perhaps a magic way for our "will" to overcome the laws of nature, that sort of free will is ... inconsistent with what we know of nature.

      Where I think the struggle is, is to understand that while determinism implies that, like everything else which isn't just random, our choices themselves are effects which were caused by previous events, that doesn't mean we are puppets. at least, not in my view. We make those choices, of course based on previous experience and how the various chemicals in our bodies make us feel at the moment and how many functioning neurons we have. How else could we make them, and why would we want to them to be independent of all past events? Don't we want our choices to be determined by evidence and reason? That is what determinism, to the extent it exists, allows us to do.

      I think of "free will" as the legal meaning, that our choices are not being compelled by other entities, not forced upon us against our own desires and own reason. In that sense, determinism is what gives us the opportunity for will (free or otherwise), to make choices and to learn from how they turn out. Determinism is what motivated Einstein to remark that insanity is doing the same thing (cause) and expecting a different result (effect). So I like the legal definition and don't really see what all the fuss is about, unless, as I started with, some people believe there is also magic.

      Probably we should start with the definition of "will". I take it to mean the capability to make decisions which influence future events. A branch in water goes where the current takes it, a fish can make choices, but a fish with a hook in its flesh does not have free will. (Those must not be the definitions which the people who argue about free will use.) (I am okay with the operation of "will" being a mechanical process which ultimately is analogous to a branch in current because I still see a useful distinction between the branch and the fish; the fish uses much more information from its environment. Differences in degree can amount to differences in kind.)

    7. Hmm! The more I've thought about the whole no-free-will thing, the more it makes sense for me. This comment further expands on Superdeterminism means in practical terms. (I've come to the conclusion to fully understand Superdeterminism, I'll just have to become a physicist; that's on my 'bucket list' now :) )

    8. For what it is worth (which is what you paid for it), I currently think that probably the key point of super-determinism as a theory is that there is no actual quantum randomness (or perhaps a variation would be, less randomness than seems to exist) but total determinism instead; whereas the current consensus is that things seem deterministic on the macroscopic level of our lives, but are very random at the sub-microscopic level. (Statistically predictable, though.)

      Personally I think either situation is a workable way to operate a universe (as long as super-determinism produces pseudo-randomness), but I have encountered (online) several people more learned in physics who seem to absolutely abhor super-determinism as a theory. Dr. Scott Aaronson is one of them, I am sorry to say. (Plus a couple philosophers, but I don't pay as much attention to them as they seem rather closed-minded to me.) I wish Drs. Aaronson and Hossenfelder could discuss this and reach a mutual understanding (and let us know what it is). But they have other important work to do, of course.

    9. So where do we stand? Determinism (*) is false "for all we currently know" while people have different opinions about free will, opinions that science cannot either confirm of negate. Furthermore, free will is not the topic of this post, so let's leave that burning disagreement aside. But [super] determinism is. And I find it very strange that the superdeterminism hypothesis is not explicitly linked to the failure of the old, "Newtonian" determinism (not Newton's idea).

      Furthermore, I find determinism and superdeterminism "logically incoherent ideas" for the simple fact that we implement determinism in the computers we build and we know that computers cannot create in general, and do science in particular, meaning generate hypotheses, test them, and reach scientific conclusions. They cannot do that even theoretically. So, if superdeterminism were true, we would be computers, therefore we wouldn’t be able to conduct the science to confirm superdeterminism.

      (*) Determinism is the idea that the future is 100% determined by the past, not that the future is a function that includes the past along with other factors - possibly randomness and free will among them. As an aside, a LOT of people don't get the 100% part.

    10. "computers cannot create in general, and do science in particular, meaning generate hypotheses, test them, and reach scientific conclusions"

      Factually wrong. Computers have generated hypotheses, tested them, and reached conclusions. Will this stop you from making this evidently false claim? Most likely not.

    11. I saw the above comment in the recent-comment lists, which just shows the first sentence, with a reaction of disbelief that Dr. Hossenfelder could be stating that. Which of course she isn't.

      Still, it is a common belief, I think due mostly to the fact that are no nerves which monitor brain neurons, so we cannot innately sense how our brains work. It turns out they don't work by magic, but by the same physics that govern everything else.

      A secondary reason is the sheer scale: about 100 billion neurons working in parallel. So far the most neurons that have been simulated on a computer is about one million, about enough to simulate a mouse's brain. (Dogs have up to 500 million neurons.) As I and others have said, at some point differences in degree become differences in kind, for practical purposes. I am not sure we will ever develop computers with 100 billion neuron capacity, but even their current mouse-brains, when dedicated to specific well-defined but complex tasks such as chess, Go, and protein folding, can out-perform us.

      I believe the final step in understanding human success (to be non-magical) is to recognize the basic algorithm we use: trial and error, plus memory of past trials. (Think of the great inventor Thomas Edison, for example.) This is an algorithm which can be implemented in computers, and has been, to great success. (Example from my own career: the GE-90 jet engine gas-path was designed by an iterative computer program, called "InGEnius". NASA has several similar examples. See "genetic algorithms" and "Monte Carlo method".)

      (Acknowledgement: while the opinion is my own, I had to learn the facts on which it is based from many sources, some of them at this site, over a lifetime.)

    12. Hi all, If I may interject:
      'Free will' seems to not really play into how a deterministic system works out, practically speaking, from what I understand (which is only what Dr. Hossenfelder et. al. have described in plain English mostly, I admit... I've physics knowledge slightly above that of a potato).
      If one could cast a big enough light-cone from the Big Bang through space-time, at some point it will touch everything in the future including events we interpret as random, and all the computations and experiments and results ever made and produced. I don't see this as preventing events happening at least as if at random from the perspective of humans.
      as for 'no free will', perhaps the concept of 'free will' is similar to spirituality and religion - experiences and beliefs that seem to be artifacts of how human brains work.

    13. Sorry. I sense anger therefore, while strongly disagreeing with the latest counterarguments, I will stop here.

    14. Nonlin.org1:35 PM, March 25, 2021

      You mean you sense you've lost the argument, so you fire off a parting shot, smearing the person who has pointed out your claims are plainly wrong as "angry", and fail to respond to the arguments. You have missed an opportunity to learn. What a pity.

  46. About superdeterminism, it is clear that "the measurement outcome is partly determined by the measurement settings". (agree). But the part that goes "In this case, the cat may start out in a superposition, but by the time you measure it, it has reached the state which you actually observe. So, there is no sudden collapse in superdeterminism, it’s a smooth, deterministic, and local process".
    You cannot have both: either you believe the cat was in (and had reached) a certain state at the time you measured it, or you follow the Copenhagen line as to being in a superposition of 2 states, the question of which one being meaningless.

    Superdeterminism, as all determinisms, does not live well with superposition. Or at least it must profess that this concept is just a practical mathematical concept for our impossibility to know the state of the system before we measure it, that is, it equates to acknowledging the impossibility of 'predicting' the state of the system.

    In summary, as I (humbly) see it. The cat is not in a superposition. It is dead or alive. It only happens that we cannot predict its state -even in principle!

    If we twist the words a little into clarity: It is WE that are in some strange state with respect to the cat, call it superposition or whatever: the strangeness consists in the irrefutable, puzzling but simple fact that we cannot predict its state before we measure it.
    All the glamour and weirdness of QM is shorthand for this fact.

    Now can this view lead us to a positive outcome?
    (Negative observations are easier to do than positive ones, but also far less useful).

    Maybe, if it leads us to focus on the exact reason why we cannot predict the state of some system 'even in principle'. If one is a superdeterminist, this is the right question to ask and the hard answer to look for.

    IMHO the key to the puzzle is not far away from us and it will be soon disclosed, but first we must overcome the 2 big problems that you mention elsewhere: Bad methodology and group thinking.

  47. Imagine a hard box made of an unbreakable stuff that contains (you are told) a certain amount of money, in cash. You need to know how much. The problem is you cannot look into it. And you cannot open the box unless you blow it up (and destroy some of the money, essentially altering the content).
    Imagine someone brings a device, a very special one, that overcomes that limitation. It can 'look' inside the box and tell you about its content. Unfortunately, it cannot tell you the exact amount of money inside, but can only provide you with an estimation: it tells you the probability that it contains any amount that you ask for.
    Would you say that the question of its content is meaningless?
    Would you accept the view that the money is in a superposition of say n states (the possible amounts inside box)?
    You could do that, provided you understand that this is just a 'practical' way of dealing with the problem, not a fundamentally correct one. Even if it works, and even it it provides you with the 'best' answer available in practical terms, you wouldn't be mislead into 'believing' that kind of reasoning.
    You coud say, what is the difference. If we cannot know the content, we just as well can talk of it being in superposition, of hidden or whatever. It doesn't make any difference.
    Well it might make a difference: The 'common sense' approach does enable you -it raises the probability- that you some day find out about what the box consists of. You are more likely to better understand the box, if not the amount of money inside. You may even end up building one such box!

  48. - Copenhagen says: Dont look at the box. It has no meaning.
    - Pilot wave: This is how the box works. (But of course, it is wrong).
    - Many worlds: I got crazy after looking at this for too long.

  49. To somebody unfamiliar with the measurement problem of QM the above metaphor comes handy:
    You cannot know the exact content of the box even by measuring it, for the act of measuring (breaking the box) alters its content. The result is always a concocted result from the actual (unknown) content and the act of measuring it, constrained only by probability laws of QM. Only in this sense it is understandable to consider the question as to the original value-content as senseless.
    It comes down then to a question of preference or 'taste' how do you think of the 'original' value that you are measuring.

  50. Hello Sabine,

    You prefer superdeterminism compared to spooky remote action.
    Do you have any vision of how this should work???
    Do you have any imagination of how this can work?
    I don't expect a fully formulated theory.
    But do you have any idea that a 12 year old child can understand?
    You mention "nonlinear theories". Do you have anything more on that?

    BTW, I like the experiment you mention in the arXiv
    I'll keep my fingers crossed for it.

    Greetings Stefan

  51. Had a thought earlier that still doesn't seem totally stupid to me...
    In connection with the realization - from the episode with the baby - that with constant energy per volume and increasing volume of the universe, the energy content of the universe increases...
    - what "yes, that guy again" said... -
    Could it be that something like coincidence emerges from this, even if one takes a deterministic approach?*

  52. Good Morning.
    Strangely enough, I'm drawn to this blog entry again.
    It's one of those days when I mentally draw a comic book version of something that would otherwise leave me perplexed:
    In a gloomy urban canyon, Superwoman explains to Batman that flying is actually very simple... you just have to want it hard enough and it'll work.
    Batman looks deep into her eyes, lets his gaze wander to her cleavage & says: "I don't think so."
    ... whereupon she gives him a kick in the ass and in the next picture he flies grinning over the roofs & thinks: "Well, I guess she is right after all."
    . ^.^ , ° [ by the way... congratulations. ]

  53. Gut ein. :)
    According to Douglas Adams in 'Thanks for All the Fish', trick to flying is to fall over and forget to hit the ground. ;)

  54. . ^.^ , °[ & occasionaly to use a Sony Walkman. ]

    1. :) I've been walking along the road outside my mother's place listening to music, the countryside is beautiful.

      Btw, I feel like I've come a fair way along with Superdeterminism/no free will from the confusion I had about 6 months ago. Progress!


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