• jgill
    3.8k
    Another way to say this is that if you start with a 0 (e.g., "nothing") and end up with a 1 (e.g., "something"), you can't do this unless somehow the 0 isn't really a 0 but is actually a 1 in disguise, even though it looks like 0 on the surface.Roger

    You might consider rethinking your analogies. :roll:
  • Roger
    30
    Or not. Why?
  • EugeneW
    1.7k


    There are lots of alternatives. But considering the current observations, this model fits the best as far as I know, and offers a dark energy mechanism (the 4D space).



    What I meant is, why can't the Schrödinger cat actually collapse without someone looking, observing. Standard QM says this doesn't happen but there are theories with an objective collapse.
  • noAxioms
    1.5k
    What I meant is, why can't the Schrödinger cat actually collapse without someone looking, observing.EugeneW
    First of all, I balk at the word 'looking', since it makes it appear that humans or life forms play a preferred role. I can think of only one interpretation that suggests that, and even it was abandoned by its author (Wigner) due to it being driven to solipsism.
    Secondly, I am not offering a falsification of objective collapse interpretations, but the relational interpretation isn't one of them. Relative to what system would the cat collapse without said system measuring the cat?
  • EugeneW
    1.7k


    In standard QM, human observers play that special role, and together with the probabilistic interpretation, this leads to strange scenarios (like many worlds).

    The bottle with poison breaks and kills the cat or not. If the superposition of, say, spin (thumb,) up and down interacts with a photon from outside, the photon can make it collapse to up (cat lives) or down (cat dies). Before the photon hits the superposition, the cat is just alive. So it's the spin that gets realized relationally. Likewise, all positions of particles make sense only because of interaction. Only relative to other positions they are meaningful.
  • universeness
    6.3k
    Does the term skeuomorphic ontology mean anything to you? Any sense can be applied to both of these wordsWatchmaker

    Such terms are easily looked up using internet searching.
    From the internet, Skeuomorphs are typically used to make something new feel familiar.
    My career is in computing and we use emulators so I am familiar with this concept.
    Computing also uses ontology all the time as a way to group and categorise data into types.
    So I would assume you are describing a method of categorisation into familiar types.

    So the liar's paradox is categorised as a paradox found in the mathematical sub-topic of propositional logic. Paradoxes don't happen in real-life, in real human experiences. They are merely constructs of mathematical logic. You don't get a barber who won't shave themselves or a liar who makes the statement 'I am a liar' as no human being tells lies exclusively. Other paradoxes such as 'The only true fact is that there are no true facts,' are also flawed as there is no rigorous definition of the term 'true fact.'
    I have no idea if this relates to what you are trying to say by using the term 'skeuomorphic ontology,' but I gave it a shot anyway. Perhaps it would be easier if you were less cryptic about the points you are trying to make.
  • universeness
    6.3k
    That's a poor representation of Rovelli's interpretation. It makes it sound like humans or things that 'observe' make any difference, which couldn't be further from what he saysnoAxioms

    Ok, It could well be that I was not attentive enough when watching Rovelli on YouTube.
    So, I assume you are saying that according to Rovelli, it's not the observer that's causing the waveform collapse it's the local interaction between x and y.

    Exactly, except I'd not have used the word 'observer'. Measurer maybe.noAxioms

    An observer can measure, whether it's human or sensor, I think you are making an unimportant distinction here.

    The universe (as a whole) doesn't need an origin story, lacking anything that measures the universe. That would require an external observer. Internal interaction only results in self-consistent state.
    Rovelli says no system can measure itself, which doesn't mean I can't see my arms, but it means the cat in the box cannot collapse its own wave function relative to the observer outside the box. The live cat cannot measure dead parts despite being in superposition of being dead and alive.
    noAxioms

    Humans desire an origin story for themselves and therefore for the Universe. I think that desire is significant even though I agree with all of Carl Sagan's great demotions.
    I understand your narration of Rovelli's view of Schrodinger's cat from the reference frame of the cat but you said earlier that only an observer from outside of the Universe can make measurements on the Universe that would reveal its true structure (is that what you are saying?). Does this not suggest that an observer outside of the box containing Schrodinger's cat should be able to know if the cat is dead or alive or is it merely the fact that the observer outside the box cannot see through the box?
    If so, then surely you are assuming that anything outside of the Universe would have an ability to interact with the Universe. As I have said before, my expertise is computing not cosmology but cosmology is of great interest to me.
  • EugeneW
    1.7k
    I have never understood the "commotion" involved in Schrödinger's cat. As long as the state of superposition is undisturbed the cat is alive, so not in a superposition of dead and alive. If the cat will stay isolated in the cage though then the cat will slowly dilute into the whole universe. As will any system devoid of interaction with the world surrounding it. So systems own their localization to interaction, which makes them relational in a way.
  • EugeneW
    1.7k
    An observer can measure, whether it's human or sensor, I think you are making an unimportant distinction here.universeness

    In the standard interpretation of QM, this distinction is made and together with the fundamental probability this gave rise to many worlds interpretation, decoherence, and other mechanisms.
  • Watchmaker
    68




    Thanks for taking a stab at that. I just made that term up. Sometimes phrases will come to mind that I think hold some key to further understanding. It's just a weird quirk of mine.
  • Watchmaker
    68


    I've never understood Schrödinger's cat. You put a cat and poison in a box, and at some point, the cat will be alive and dead at the same time.

    Can you explain this to a 6 year old? I will be the 6 year old of the forum here if anyone wants to bounce any ideas off of me.

    Also, are the numbers on unscratched lotto tickets in a state of superposition?
  • EugeneW
    1.7k


    Throw away the macroscopic objects in superpositions. In a superconductor, Bose-Einstein condensates, or other exotic states of matter, there are a lot of constituent particles in superposition, but a cat in a superposition of a live state and dead state is nonsense, as the 6 year old would testify to. The standard rules of QM assign such state to a cat because it inherits the superposition of the superimposed state which leads to poison or not, upon measurement. The wavefunction of the cat-up-down-superposition becomes is a superposition of a poison-deadcat and a nopoison-livecat state. That's the weird implication.

    The better way to look at it is to consider only the spinup-spindown state in superposition. The cat is just alive and an act of measurement collapses the state to up (cat alive) or down (deadcat). In alignment with the expectation of the six year old.
  • noAxioms
    1.5k
    The bottle with poison breaks and kills the cat or not. If the superposition of, say, spin (thumb,) up and down interacts with a photon from outside, the photon can make it collapse to up (cat lives) or down (cat dies). Before the photon hits the superposition, the cat is just alive.EugeneW
    None of this is expressed as a relation, so the assertions of state are according to different interpretations. 'The superposition' is not an object which a photon can hit. If a measurement of the spin of some particle is taken, it usually involves information (photon?) traveling from the state being measured to the measurer, not the other way around.


    It could well be that I was not attentive enough when watching Rovelli on YouTube.universeness
    YouTube almost always uses human observers in their examples, and yet in real experiments, the human is often not present during any of the measurements, all of which are taken and recorded by inanimate equipment, say a screen upon which an interference pattern appears.

    So, I assume you are saying that according to Rovelli, it's not the observer that's causing the waveform collapse it's the local interaction between x and y.
    According to quantum mechanics theory (rather than any metaphysical interpretation of that theory), there is no evidence that humans play a special role in physical waveform collapse. Humans do play a role in epistemological collapse: Even if somebody else watched, one particular lab guy isn't going to know where the photon was detected without at some point measuring the result, however indirectly. That doesn't mean that the photon didn't in fact get measured at a particular location.

    An observer can measure, whether it's human or sensor, I think you are making an unimportant distinction here.
    I'm balking at the connotations of using human verbs (like 'looking') when describing an interaction of any kind between two arbitrary systems. It is precisely that language usage that caused the naive readers back in the day to conclude that QM somehow provided evidence that humans were special. And, the 'oberver' need not be a sensor at all. It need not be anything designed with the purpose of specifically measuring the system. A photon can hit, instead of a photo-sensitive screen, just a black wall and be lost forever. The wavefunction is still collapsed relative to the system containing that wall.

    Humans desire an origin story for themselves and therefore for the Universe. I think that desire is significant even though I agree with all of Carl Sagan's great demotions.
    Totally agree. Humans want this. How to explain the reality of whatever it is that you must assert to be objectively real to satisfy your desire for warm fuzziness. But the explanations always require dancing around an inevitable contradiction, and it seemed far simpler to not assert the objective reality in the first place.

    I understand your narration of Rovelli's view of Schrodinger's cat from the reference frame of the cat but you said earlier that only an observer from outside of the Universe can make measurements on the Universe that would reveal its true structure (is that what you are saying?).
    By definition, there can be no such observer. Any such observer would be part of the universe.
    I grant that similar to a simple quantum system in a thought experiment, the structure of the entire universe can be considered from 'outside', but that's different than measuring. No wave function collapse results from objective analysis of a wavefunction of some closed system.

    Does this not suggest that an observer outside of the box containing Schrodinger's cat should be able to know if the cat is dead or alive or is it merely the fact that the observer outside the box cannot see through the box?
    I have no idea what I wrote that might suggest the outside observer could acquire knowledge concerning the state of the unmeasured cat.

    If so, then surely you are assuming that anything outside of the Universe would have an ability to interact with the Universe.
    Again, that would make the observer part of the universe, and not outside it.

    As I have said before, my expertise is computing not cosmology but cosmology is of great interest to me.
    Cool. I'm a software engineer myself, hardly a cosmologist.
  • EugeneW
    1.7k
    'The superposition' is not an object which a photon can hit.noAxioms

    Superposition is collapsed by a virtual photon. An interaction is involved.
  • universeness
    6.3k

    Ok EugeneW! I defer to your more detailed knowledge of the topic in comparison with mine.
  • universeness
    6.3k
    You typed:

    The universe (as a whole) doesn't need an origin story, lacking anything that measures the universe. That would require an external observer.noAxioms

    I took this to mean that only an external observer of the Universe could make measurements/perform experiments on the Universe (as a whole) and by doing so, discover its structure and workings.
    I took it that you were basing this view on your other view that internal measurers (human or electronic sensor) cannot gain the necessary data as they are part of the Universe.

    You then typed in your last response to me:

    By definition, there can be no such observer. Any such observer would be part of the universe.
    I grant that similar to a simple quantum system in a thought experiment, the structure of the entire universe can be considered from 'outside', but that's different than measuring. No wave function collapse results from objective analysis of a wavefunction of some closed system.
    noAxioms

    Are you using the argument that no observer can exist 'outside' of our Universe?
    If that is the case then are you saying we can never know the origin story of the universe based on the points you make that an outside observer would be needed and such cant exist and internal observers cant do what's required and this view is Carlo Rovelli's viewpoint. Is that what you are saying?

    If an observer can be conceived as 'outside' of the Universe then how would they be part of it?
    That makes no sense to me.
    What evidence are you calling upon that demonstrates that objective analysis of a waveform is a closed system? What if there are > 3 dimensions or the multiverse is real, or the Universe is layered, or time is not linear and is in fact, multidimensional etc, what are you defining as 'objective' and 'closed'?

    I am trying to follow a smooth line of logic in your narration of 'The structure and workings of the Universe,' as suggested by Carlo Rovelli. I have tried to narrate the basics of his viewpoint as I conceive it, based on the youtube videos he offers. You may have a better understanding of his viewpoint than I do. I am merely trying to understand what you are presenting based on my limited grasp of the cosmological theories involved.
  • EugeneW
    1.7k
    If a measurement of the spin of some particle is taken, it usually involves information (photon?) traveling from the state being measured to the measurer, not the other way around.noAxioms

    A state of superposition remains superimposed without interaction. A superposition of spin up and down won't collapse by emission of a photon carrying info to the observer. Measuring the spin means placing the superposition in an external field.
  • jgill
    3.8k
    Superposition is collapsed by a virtual photon.EugeneW

    Which sounds more abstract, even mystical, than most of mathematics. Are things really that bizarre in the quantum realm, or is a dramatic paradigm shift over the horizon, awaiting an Einstein? How much of the weirdness is due to limitations of experimental investigations?

    Long, long ago I thought of majoring in physics, but found the concepts of mathematics were clearer to me.
  • EugeneW
    1.7k


    All particles interact by coupling (by their charge) with the virtual particle field between them. So the up/down superposition, two simultaneous paths in spin space, gets collapsed to up or down after this coupling. The virtual particles are not virtual in the sense that they don't exist but in the sense that their energy and moments (or times and positions) are independent, delivering the right values for the transition. Mathematically, the propagator for a virtual particle is the integral over all momenta and energies and in a larger diagram, with external legs representing real particles, deltas ensure the right momenta and energies are picked for the interacting real particles. :cool:
  • EugeneW
    1.7k
    Long, long ago I thought of majoring in physics, but found the concepts of mathematics were clearer to me.jgill

    That could because one speaks of values only, without yet a content.
  • noAxioms
    1.5k
    Superposition is collapsed by a virtual photon. An interaction is involved.EugeneW
    That might be one way, especially for a realist interpretation.

    You seem to envision poking the cat with a stick, but measurement of the moon does not seem to involve virtual photons, so collapse does not necessarily involve such a virtual interaction.

    A state of superposition remains superimposed without interaction. A superposition of spin up and down won't collapse by emission of a photon carrying info to the observer. Measuring the spin means placing the superposition in an external field.EugeneW
    You have a reference for any of this? This seems to violate locality for one thing.

    The universe (as a whole) doesn't need an origin story, lacking anything that measures the universe. That would require an external observer.
    — noAxioms

    I took this to mean that only an external observer of the Universe could make measurements/perform experiments on the Universe (as a whole) and by doing so, discover its structure and workings.
    universeness
    I didn't mean that with that comment, which was specific to the relational interpretation.
    I don't see how 'experiments' could be performed by an external observer given definitions and models where such an observer is meaningful.

    A model could in principle be simulated by something not part of the universe modeled, and experiments might consist of different initial conditions or something.

    I took it that you were basing this view on your other view that internal measurers (human or electronic sensor) cannot gain the necessary data as they are part of the Universe.
    I forget the context of when I said that. Data necessary for what again?

    By definition, there can be no such observer. Any such observer would be part of the universe.
    I grant that similar to a simple quantum system in a thought experiment, the structure of the entire universe can be considered from 'outside', but that's different than measuring. No wave function collapse results from objective analysis of a wavefunction of some closed system.
    — noAxioms

    Are you using the argument that no observer can exist 'outside' of our Universe?
    By definition, given the relational (or any non-counterfactual) interpretation, nothing external (or even sufficiently distant) can exist since it cannot be measured. But given a different definition of 'exists', the rules might be different.

    are you saying we can never know the origin story of the universe based on the points you make that an outside observer would be needed ...
    There is no origin story. Only a realist interpretation requires an origin story to explain the reality of whatever is asserted to be real. Positing an 'outside observer' doesn't change that.

    If an observer can be conceived as 'outside' of the Universe then how would they be part of it?
    That makes no sense to me.
    Totally agree. So if it interacts, it is not outside. If it's outside, it can't interact.

    What evidence are you calling upon that demonstrates that objective analysis of a waveform is a closed system?
    I'm not suggesting it necessarily is. The wavefunction of the universe is supposedly by definition closed, and thus an analysis of 'the universe' (defined as that wavefunction) would be an analysis of a closed system, but open systems can also be objectively analyzed.

    hat are you defining as 'objective' and 'closed'?
    Objective is an adjective which I am using in opposition to 'relative'. Objective existence is realism: The ontological property of existence even in the absence of observation. Relative existence is a relation: A exists to B, but A might not exist to C.

    I am trying to follow a smooth line of logic in your narration of 'The structure and workings of the Universe,' as suggested by Carlo Rovelli.
    I'm not trying to convey Rovelli's views. I've not read the work you name. But the view is at least loosely based on his concept, but driven to its logical conclusion.

    I have tried to narrate the basics of his viewpoint as I conceive it, based on the youtube videos he offers. You may have a better understanding of his viewpoint than I do.
    Or not... Not sure if I'd score better than you on a test of his works.
  • EugeneW
    1.7k
    You seem to envision poking the cat with a stick, but measurement of the moon does not seem to involve virtual photons, so collapse does not necessarily involve such a virtual interaction.noAxioms

    Even the Moon is measured with virtual photons. Though they are almost real.
  • EugeneW
    1.7k
    Every non-interacting system will get spread over space. So their spatial properties depend on other particles. So their properties are relational. Measuring is a two-way process.
  • universeness
    6.3k
    I'm not trying to convey Rovelli's views. I've not read the work you name. But the view is at least loosely based on his concept, but driven to its logical conclusion.noAxioms

    I think we have been mostly talking past each other. I thought you were narrating Rovelli's views as your first response to me stated:

    That's a poor representation of Rovelli's interpretationnoAxioms

    I think Rovelli's posit that the measurement problem and waveform collapse is a localised phenomena which only occurs between interacting systems X and Y and is not a 'Universal/objective effect,' is very interesting. The waveform does not collapse from the reference point of the whole Universe.

    I don't think Rovelli has ever suggested that the structure and fundamental workings of the Universe are unknowable because those who are trying to discover such are part of the Universe they are trying to explain.

    I've not read the work you namenoAxioms

    This is an example of what I mean by 'talking past each other' or misunderstanding.
    I have WATCHED his youtube videos, his lectures and his discussions with Sean Carroll etc.
    I haven't READ any of his publishings.
  • EugeneW
    1.7k
    The wavefunction collapse is a real local collapse. Only a universal wavefunction of non-interacting particles will never collapse. Collapse is interaction.
  • noAxioms
    1.5k
    I'm not trying to convey Rovelli's views. I've not read the work you name. But the view is at least loosely based on his concept, but driven to its logical conclusion.
    — noAxioms

    I think we have been mostly talking past each other. I thought you were narrating Rovelli's views
    universeness
    It says 'loosely based'. Rovelli certainly has the physics part down, but not having read his works, I don't know if he's explored the philosophical implications of his ontology, such as that of identity for example.

    your first response to me stated:
    The collapse of the wave function due to the act of observation?
    — universeness
    That's a poor representation of Rovelli's interpretation
    — noAxioms
    I restored some of the context. That reply of mine referred to your usage of "act of observation" which sounds like a pop wording at best, and not how a physicist might have put it.
    'Act' makes it sound like some action or intent is required, and 'act of observation' makes it sound like a human is required to be involved in the act. There's never been evidence of this. A rock can take a measurement and collapse the wave function of some non-rock system just fine, all without actually observing or knowing anything. So it was the pop-representation that I meant to label a poor representation of the science, and not of Rovelli's view in particular.

    I think Rovelli's posit that the measurement problem and waveform collapse is a localised phenomena which only occurs between interacting systems X and Y and is not a 'Universal/objective effect,' is very interesting. The waveform does not collapse from the reference point of the whole Universe.
    With that we seem to both agree. It implies that a wavefunction has a location (which I would not have intuitively suggested), and that a wavefunction of a distant system relative to 'here' is nevertheless 'here'.

    I would not have said that spatially systems can 'interact' since I consider a system to be essentially an event and not say a worldline like Rovelli implies. We obviously differ on this point, but I can drive the worldline view to contradiction, a philosophical problem which seems not to concern Rovelli, being a physicist mostly interested in empirical consistency.
    Two events cannot 'interact' since that would require each to be in the other's past light cone.

    I don't think Rovelli has ever suggested that the structure and fundamental workings of the Universe are unknowable
    Did I suggest anything along those lines?

    I have WATCHED his youtube videos, his lectures and his discussions with Sean Carroll etc.
    I haven't READ any of his publishings.
    Perhaps you can recommend some Rovelli vids, even though I don't usually get my science from videos. Then I can point out places where I might not agree with Rovelli.
  • universeness
    6.3k
    It says 'loosely based'. Rovelli certainly has the physics part down, but not having read his works, I don't know if he's explored the philosophical implications of his ontology, such as that of identity for example.noAxioms

    I don't recall much mention of any philosophical aspects/consequences of his theories, that he discussed in his YouTube offerings but I was too busy trying to gain some understanding of his scientific musings.

    Here is an audio podcast between Sean Carroll and Carlo Rovelli. It is an episode from Sean Carrolls 'Mindscape' series and is titled: Episode 2: Carlo Rovelli on Quantum Mechanics, Spacetime, and Reality.




    A rock can take a measurement and collapse the wave function of some non-rock system just fine, all without actually observing or knowing anything.noAxioms

    I have no idea what you mean by this? A rock can take a measurement? in what sense?
    I assume you don't mean this literally but I don't get it, if it was meant as a metaphor for something else.
    I assume you just mean that you don't need the presence of a human conscience to collapse the wave function of a process such as the interference pattern produced by the double split experiment or entanglement.

    With that we seem to both agree. It implies that a wavefunction has a location (which I would not have intuitively suggested), and that a wavefunction of a distant system relative to 'here' is nevertheless 'here'.noAxioms

    Well, a wave function will produce a waveform, will it not? and all waveforms moving in 3D space will produce a worldline as it traverses space from its origin. Like a drop of water in an ocean that will cause only a localised disturbance and then settle as it dissipates its energy. It does not affect the entire ocean. I don't know what you mean by the wavefunction of a distant system relative to 'here' is nevertheless 'here'. light waves from a distant star still have to traverse the distance between here and its origin, which is why we see what was, not what is. maybe I am being a bit dense here but I am not following your logic very well.

    I would not have said that spatially systems can 'interact' since I consider a system to be essentially an event and not say a worldline like Rovelli implies. We obviously differ on this point, but I can drive the worldline view to contradiction, a philosophical problem which seems not to concern Rovelli, being a physicist mostly interested in empirical consistency.
    Two events cannot 'interact' since that would require each to be in the other's past light cone
    noAxioms

    I think I understand your words but then how do particles 'interact.' Perhaps can explain to me what you mean more clearly. I often turn to him, regarding cosmology stuff that I dont fully grasp.

    Did I suggest anything along those lines?noAxioms

    Not about Rovelli, no I don't think you did. You stated that observers cant fully understand a system that they are a part of so it's that which I disagree with. A system which is capable of successful self-diagnosis and self-maintenance would have to know how all of its parts worked individually and as sub-systems and as a whole system. If this can be achieved electronically then it must be possible in the case of the universe. I am not claiming that we have produced such an electronic system yet but we are getting much better at it.

    Perhaps you can recommend some Rovelli vids, even though I don't usually get my science from videos. Then I can point out places where I might not agree with Rovelli.noAxioms

    Here is another one you might like that I watched a few months ago:

  • EugeneW
    1.7k
    Act' makes it sound like some action or intent is required, and 'act of observation' makes it sound like a human is required to be involved in the act.noAxioms

    In standard QM this is actually the case.

    An event in physics is not actually an event. It's the time and position of a particle. If particles were devoid of charge all individualities of partìcles would be lost and the universe would spread out into a uniform mass in which nothing could be defined or have outlines. All would be one. When particles interact, by their charges coupling to the omnipresent field of virtual particles, their evolving wavefunctions (which are, loosely speaking, the temporal cross sections of quantum fields) collapse every time upon an interaction. The standard view doesn't speak of collapse but the objective collapse approach does.

    So particles tract characteristics and identity because a relation with other particles. Their condensations in spacetime are relational.
  • EugeneW
    1.7k
    I think I understand your words but then how do particles 'interact.' Perhaps ↪EugeneW can explain to me what you mean more clearly. I often turn to him, regarding cosmology stuff that I dont fully grasp.universeness

    It's easy and difficult at the same time. There is a field of virtual particles in empty space. If a charged particle moves through space it couples to this field. How can they couple if they are point? Simply because they are no points. Their coupling to this field cause that field around them to change. Same for other particles. This means that if a particle enters a region of space where that virtual field is disturbed by another charge (say both charges are electrical, which couple to virtual photons only), it will not move the same as before (unchanging velocity, apart from the "Zitterbewegung"). It's accelerated because of the potential created by the other charge (which actually is a so-called virtual photon condensate). These interactions happen in measurements, and take place continuously to maintain individuality of the parts. Bosons though don't have individuality when in groups.
  • EugeneW
    1.7k
    So it's not charges causing a potential energy field. Photons are not emitted or absorbed. The charges couple to this omnipresent virtual field.
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