- #1
Amateur level.
Does the delayed-choice double slit experiment violate or put in trouble the standard cause-and-effect thinking?
Does the delayed-choice double slit experiment violate or put in trouble the standard cause-and-effect thinking?
Gerinski said:Does the delayed-choice double slit experiment violate or put in trouble the standard cause-and-effect thinking?
Gerinski said:Does the delayed-choice double slit experiment violate or put in trouble the standard cause-and-effect thinking?
Gerinski said:Maybe an extension of the question: "what does the delayed-choice experiment tells us about time?"
(I know there's no answer, just opinions :-)
mccrone said:... QM nonlocality is proof that simple cause and effect thinking (which embodies the mechanical principle of locality) cannot be the whole story.
Sherlock said:Quantum nonlocality has to do with global contexts, systems of correlated
spatially separated measurments rather than individual (local) measurements.
Sherlock said:The time of an event is the configuration (the reading) of a clock
correlated with the event (which is itself a configuration of some
set of objective phenomena -- eg., a ball contacting a bat, a spot
of light appearing or disappearing, a fire igniting, a picture hanging
on a wall, a moving car passing a stop sign, a car sitting in a
driveway, etc.).
Sherlock said:Effects can't come before causes because that would simply be misusing the terms.
mccrone said:It is to do with temporal as well as spatial
correlations. So delayed choice twin slit experiments are a stark demonstration.
mccrone said:This might be how a human observer chooses to index
events - motivated by a belief in cause and effect or locality. But nonlocality raises the question of when an event really occurs.
The point I was making was that a global scale observer would
see both ends of an event as part of the same effective moment.
So both the photon emission by a star in some distant galaxy and
its "much later" absorbtion by my eye.
mccrone said:What the proof of nonlocality tells us is that locality-based models of causality are incomplete (though they are certainly still useful). So I was talking about the kinds of models based on hierarchy theory that might present a different view of time.
mccrone said:Yeah but then you have the problem of the chicken and the
egg. Cause and effect thinking runs into paradoxes - like how
can a something (the universe) spring out of a nothing.
mccrone said:So to get out of this, you have to look into other causal models.
So for example, ones that start with a state of vague everythingness (cf: Anaximander, Peirce) and then dichotomise or symmetry-break to produce two crisp limits on being. So we would now start with a vague chicky-egginess and watch it divide asymmetrically into a chicken and egg
(or if you like, the first egg inside the first chicken). So now causes are effects.
mccrone said:I realise that alternatives to locality and mechanistic logic are not fashionable. But non-locality has to be accounted for within some
causal model unless you want this aspect of reality to remain
a mystery.
Sherlock said:Anyway, cause and effect thinking isn't paradoxical. Causes
can't happen after the effects that they cause, by definition.
Given any, causally related, chicken-egg duo, either the egg
was laid by the chicken or the chicken hatched out of the
egg. If they 'sprang' into existence at the same time, then
they're not causally related to each other -- but they might
be nonlocally related as parts of a system that encompasses
them both.
Sherlock said:What remains to be understood is the deep, qualitative nature of
reality. We can describe/predict the gravitational behavior of
macroscopic objects pretty accurately, but don't know what
causes it. We can predict rates of coincidental detection in
Bell tests pretty accurately, but don't know what's happening
at the level of paired emissions. We can predict detection
patterns in photon/electron two-slit interference experiments,
but don't know what's happening at the level of the emissions
interacting with the two-slit and detection devices.
It's not a matter of reinventing or redefining causality or
time. There just isn't enough data.
mccrone said:I'm not sure I see the logic in your position here. The data tells us our causal models are inadequate. So rather than reconsider our causal models, let's gather more data.
Even if we disregard the evidence that science is theory-led rather than data-led on the whole (ie: what looks like data, what you feel is worth measuring, is determined by what you believe is probably happening), you seem to want to put unnecessary limits on enquiry.
And to return to the specific issue of temporal sequence, are you saying that delayed choice twin slit experiments don't seem to put the cause of a choice of path after the apparent effect, the actual choice of a path?
Cheers - John McCrone.
mccrone said:This kind of mutual causality can arise in the most unlikely places - for example, Newton's third law. For every action an equal and opposite reaction. I throw a ball and the ball "throws" me. Both action and reaction spring up at precisely the same moment. And even though you might still want to say one led to the other, put the situation into deep space - say two masses colliding - then you really don't know which exerted the action, which responded with a reaction.
mccrone said:Think then about why this strange law was necessary. Newton made the world mechanical cause and effect with the first two laws. Then had to add back in the deeper mutuality between figure and ground, event and context, as a fictitious symmetric force of reaction.
You don't need to get into QM or relativity to find causal weirdness in mechanical logic - cause and effect thinking.
Again, mechanical logic is a very effective tool in modelling. No surprise that it is first choice when pragmatism rules. But that does not close the door on broader causal models that may capture more of the truth of reality.
mccrone said:I'm not sure I see the logic in your position here. The data tells us our causal models are inadequate. So rather than reconsider our causal models, let's gather more data.
mccrone said:Even if we disregard the evidence that science is theory-led rather than data-led on the whole (ie: what looks like data, what you feel is worth measuring, is determined by what you believe is probably happening), you seem to want to put unnecessary limits on enquiry.
mccrone said:And to return to the specific issue of temporal sequence, are you saying that delayed choice twin slit experiments don't seem to put the cause of a choice of path after the apparent effect, the actual choice of a path?
Sherlock said:In the case of two bodies colliding in deep space, the collision event can be said to cause the events that can be
immediately, locally related to it -- such as the fragmenting of,
or changing the trajectories of the colliding bodies.
Sherlock said:Nonlocal contexts aren't causal, they're correlational.
mccrone said:You're missing the point. Of course the third law is about locality. But even in the classical modelling of locality there is an example of chicken and egg paradox. Newton smuggled in a reaction that arises instantly (not before, not afterwards). Einstein then went on to exploit the in principle impossibility of saying one part of the system did the moving, the other part stayed still.
You could equally well say that locality is a model and therefore all that is observed are correlations with the model. If there was no problem created by nonlocality, then people (like Einstein) wouldn't have expended so much effort on hidden variable explanations.
It is easy to agree that you don't need to "explain" nonlocality if your concerns are only practical. Modelling the world in a local way captures enough truth for most human purposes. But still, nonlocality exists and is not - by general agreement - explainable by a local logic.
Locality is violated in QM. But that fact isn't visible to a local observer. The question for the modelling of nonlocality is does it make sense to talk of global observers?
Cheers - John McCrone.