A Twist on Schrödinger's Cat Paradox
scientificamerican.com
scientificamerican.com
1. The wave function does not exist in physical space, it exists in configuration space. Configuration space is the same as physical space only in the one very special case of a single non-entangled particle. The intuitions of physical space do not generally carry over into the general case of configuration space.
2. In order to produce interference you have to split up the wave function into two pieces and then bring those pieces back together again with a phase change. But since the wave function exists in configuration space, "bringing it back together again" becomes increasingly difficult as the number of entangled degrees of freedom grows. As a practical matter, it is effectively impossible to do this once the number grows beyond a few hundred (this is why building quantum computers is hard). But an actual macroscopic observer consists of O(10^23) degrees of freedom, and is also entangled with their environment. This is the reason that large systems behave classically and don't exhibit interference.
3. Whether or not a system is in a superposition is not a physical fact about the system, it is a consequence of the measurement you choose to make. A vertically polarized photon (for example) is in a superposition relative to a measurement axis rotated away from the polarization axis. For a more complicated system, the measurement axis, like the wave function itself, is in configuration space. But we can only do measurements in physical space. This is the reason that in order to see interference in an entangled system it is necessary to do multiple physical measurements and look at the correlations between them. Doing those kinds of measurements on actual macroscopic objects is way beyond the current state of the art, and may well be impossible even in principle. But this is the sort of thing that is contemplated in the theory behind these experiments. This is the reason that single particles are used as stand-ins for Wigner's friend.
Tesla based his entire electric theory on the Aether.
This theory was wrongly suppressed by results of a Michelson Morley experiment...
https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_
...which failed to measure Aether-Drift because of the fact that it was done in a basement, and which was later contradicted by Dayton Miller when he repeated the experiment on a mountain top:
http://www.orgonelab.org/miller.htm
This scientific tragedy, likely done by powerful oligarchs, set the progression of physics back 100 years. We now have fraudulent branch of particle physics, which has a terrible track record with pretty much every prediction it has made, and which would be laughed out of the scientific community if it weren't for the sustained push by the mainstream media to hammer it into the minds of intellectuals.
We've been told that light has a set speed of propagation, yet time after time there are articles posted about light exceeding the speed of light for example gamma ray jets from quasars, which is explained by positing that the space-time fabric is moving and causing the reference frame containing the light wave to increase it's speed above the limit.
https://www.sciencealert.com/faster-than-light-speed-in-jets...
The media has become so twisted that we now accept completely broken interpretations such as virtual particles (used to balance equations), string theory (completely made up and didn't work), multiple universes, time travel and a smorgasbord of hilarious interpretations from a fundamentally broken model of physics.
This article is just yet another desperate attempt to patch up this hilariously outdated physics branch. Einstein physics is on it's way out. And when it comes crashing down we will replace it with the work of Tesla and we will move faster in one decade the entire previous 150 years.
Now, we have them in many forms. The differential kind from the wiki article. The operational calculus kind from Jan Mikusi?ski's . The modeling of capacitor and/or coil as transmission lines by Ivor Catt. The fourquadrant representation from Eric Dollard.
I will appreciate any elaboration on any of the subjects.
The modelling and experimentation in the area seems to be based on an opportunity to contract space. Meaning that instead of having a 5,000 mile long wire, we are forced to be limited by our laboratory span. How can we simulate in our lab a 5,000 mile long wire? Eric Dollard proposes the analog computer. Four elements compromise a symbol. We lay the symbols in a serial line. https://www.youtube.com/watch?v=nJ8drfI4j9o
Now, we got a 5,000 mile long wire in our lab. Space contraction.
This dude does great job http://www.am-innovations.com/transference-of-electric-power...
And please don't forget that Heavside basically single-handedly created the electrician's vocabulary of terms.
The primary error there is one that people can't seem to stop making for some strange reason: if you don't measure a property X, and instead measure a (non-commuting) property Y, you are not free to say what X "would have been," and -- especially egregiously -- to use that to demonstrate a contradiction. There is no "would have been" in QM. Either you measure it or you don't, and even after you do, the value becomes invalid after it evolves or a complementary variable is measured.
Secondly, Wigner's friend was not a single particle. Asking what a single particle "experienced" only makes sense if you are a panpsychist (or "panpsychic" as amusingly misspoken in the article). In any case, it has no bearing on the essence of Wigner's question.
"But clearly, even if no one literally measures Charlie in the {|0〉,|1〉} basis, he’s still there, thinking either the thought corresponding to |0〉 or the thought corresponding to |1. And likewise Diane. Just as much as Alice and Bob, Charlie and Diane both exist even if no one measures them, and they can reason about what they know and what they know that others know. So then we’re free to chain together the “certainties” of Alice, Bob, Charlie, and Diane in order to produce our contradiction."
You can't use this argument without also explaining what "thinking" means - because in fact it makes no sense unless you assume consciousness exists as a quantum state which allows a phenomenon called "thinking."
And philosophically and practically, that's a very, very large can of wormns.
So this ends up in the usual place: it's not obvious how using an idea no one understands - like consciousness - to explain another idea no one understands - like QM - is supposed to solve any of these problems.
More details: https://algassert.com/post/1904
> OK, point taken. But if one has any experience with experiments in the foundations of QM, one knows full well what’s going to happen next. Namely: some experimental group will do a slightly souped-up test of Hardy’s Paradox, of course getting just the results that QM predicts, and will then market it in Science or Nature as “the first experimental probe of the logical contradiction at the heart of QM … who could’ve imagined that the ‘impossible’ outcome would occur with probability 1/12?” And then the science journalists will wet themselves with excitement. It’s all nearly as predictable as QM itself!
It's not just disturbing, it's going way, way beyond what the actual experiment tested. Articles like this (and even the underlying papers describing experiments like this) talk as if we are doing Wigner's friend type experiments involving actual humans. In fact the systems being experimented on are qubits, and the detectors are very simple detectors. The technical achievements involved in these experiments are certainly impressive, and experimenters should certainly continue pursuing these things, but the philosophical implications being claimed are IMO vastly overstated.
My usual argument against it is the mediocrity principle [3], we humans often fail to accept the insignificance of our existence. Thus, we tend to prefer theories which tell us that we are special. Just like the idea that we are able to trigger the collapse of the wave-function and the superposition, but a cat is not.
1: https://en.wikipedia.org/wiki/Copenhagen_interpretation 2: https://en.wikipedia.org/wiki/Vitalism 3: https://en.wikipedia.org/wiki/Mediocrity_principle
Indeed the wiki article you link to says:
> Although the Copenhagen interpretation is often confused with the idea that consciousness causes collapse, it defines an "observer" merely as that which collapses the wave function.
Which seems like a very practical, albeit obviously incomplete, approach to take.
Is there a better way to build intuitions how an information processing system would behave while being in superposition?
Things get complicated when we throw humans in the mix, perception and consciousness and all. But modelling even simpler machines and their "point of view" can be insightful.
In this day and age it shouldn't be hard to imagine the working of a computer that uses computer vision algorithms to perceive its world and take action as a result, acting as a "causality amplifier". For example image we feed it the output of some QM experiment and instruct it output a description of what it "sees" (as we routinely do with cat pictures classification).
I assume it would be far less controversial to think about the unitary evolution of the wave function if the system being described is a QM experiment plus a computer rather than the same QM experiment and a human.
Yet, there are many similarities. The output of this computer (the classification) would be in superposition, and when measured by us it would appear as if the wave function collapsed. But we could add another such computer in the mix and ask ourselves "does it also see the wave function collapsing"? Well can program it to take the measurement and record the answer and then convey the answer to us (or to another computer down the chain). These "answers" are the "point of view" of the computer. It will "observe" decoherence yet it won't be decohered itself, as its own statement about whether it observed decoherence is itself in superposition and thus can be used as a further input to other machines witnessing subjective decoherence.
It seems like there's regularly articles saying stuff like "QM implies that both outcomes happen, but it's a longstanding mystery why we only see one outcome", as if they seriously expect your hypothetical to be the consequence of QM. I'm so frustrated at that, because as you say, seeing one outcome is exactly what you'd expect to see from inside of a superposition.
It's almost as frustrating to see as it would be to see an article saying "Newton's theory of gravity says mass attracts mass, but it's a longstanding mystery why we haven't all fallen into the sun". The theory already has an answer for that if you follow the chain of consequences from it.
You can always consider your automated apparatus to be part of the system and hence governed by unitary evolution.
If the results had been kept completely isolated from all people, you could still say a measurement hasn’t occurred.
What if there is a person in an lab which is isolated from the rest of the people?
That’s something only conscious beings can do.
The friend only exists in many worlds from Winger's perspective, and only as long as their state has no causal effect on Wigner's own state.
Do you mean "he can either think he can be in superposition or he cannot be, if he thinks he can be then he would believe in many worlds, which is incompatible with 'traditional' QM, which thus implies 'Traditional QM does not allow Wigner’s friend to be in superposition.'" ?
I don't think the Traditional QM ever explicitly disallowed a person to be in superposition; being in superposition it's just not something "decent people" do, I suppose.
Thus we needed to find other ways to come to terms with what we observe. But the math is the same. The rest is only metaphors that help us reconcile what we observe with how we feel inside.
Thus, many worlds is not antithetic to traditional QM.
I don't think that's historically accurate. If you read about how Everett's ideas were treated it's pretty clear traditional QM is antithetic to many worlds.
But the QM theory is not its interpretation.
Perhaps it's only a "measurement" if the (alleged) particle has nowhere else to go after the interaction. But how does the (alleged) particle know which macroscopic interactions are terminal and should be counted as "measurements" and which are part of the rest of the experiment?
There is no answer to this in QM. You can calculate the probabilities and you will get predictable answers, but there are still >20 interpretations of what is really happening, and they all disagree with each other in important ways.
Note that the recording of information has effects outside the system, even if no human looks at the data - recording a zero or a one will require different levels of power that, while they average to a mostly constant power consumption, are there nevertheless.
What tells you those records aren't in a superposition?
The only way to determine anything about the records is to observe them, and at that point you have a human (= consciousness) in the loop. Anything you put between yourself and the experiment might be in a superposition until you observe it.
This! Now substitute the record taking device and record keeping substrate with a human brain and this stays true. To rephrase your question:
"What tells you the state of your brain isn't in superposition?"
A human in the loop is not the end of the story, it's just yet another interaction in the quantum system.
When we experience decoherence of a quantum system, we interpret it as if something happened to the thing we observe, yet what actually happens is that something happened to us (and in turn to every system that observes us, and so on).
This is all utterly unintuitive for us, who experience the world through those brains, who feel being there, conscious in the moment. That feeling is one of our strongest direct perceptions of the world, and yet it's affected by the mechanisms of the physical reality. It's hard to accept though; it runs counter to many deep intuitions we have about ourselves, our inner lives, our identity, our values, our belief systems.
But then wouldn't an external measuring apparatus (or person) observe the system in a single state instead of a superposition? Isn't that the same as a series of nested systems, each measured and having the state recorded by an apparatus that's part of a system that encapsulates it?
There are experiments that show decoherence in absence of conscious measurement. For example, https://www.physics.upenn.edu/~pcn/Course/250/Week.of.02.21/...
> Here we report matter wave interferometer experiments in which C70 molecules lose their quantum behaviour by thermal emission of radiation. We find good quantitative agreement between our experimental observations and microscopic decoherence theory. Decoherence by emission of thermal radiation is a general mechanism that should be relevant to all macroscopic bodies.
> We observe that at temperatures below 2,000 K the emission rate is negligible, whereas at higher temperatures the molecules may emit photons whose wavelengths are comparable to (or even smaller than) the maximum path separation of ,1 mm. They transmit (partial) which-path information to the environment, leading to a reduced observability of the fullerene wave nature. Around 3,000 K the molecules have a high probability to emit several visible photons yielding sufficient which-path information to effect a complete loss of fringe visibility in our interferometer.
One thing I never quite understood about the decoherence argument for resolving the measurement problem is that it forces the "collapse" to happen with local interactions. This of course makes sense since you want to think of a measurement as a "normal", unitary process. This means the environment has to "enact" the projection operator through interactions. If you have the most basic EPR pair, how can this happen? How can you decohere the wave function of the spacelike separated counterpart (B) by locally measuring the other spin (A) and then letting the environment project out the state of B through local interactions? In this experiment https://arxiv.org/pdf/1511.03190.pdf they have two detectors 60 meters apart in a subbasement of a castle. What are the interactions in those hallways that are carrying the correlation from the decoherence/measurement on one side of the experiment to the other, faster than light to maintain the correlations. This seems too basic of a question so I don't know if I'm just missing something obvious, but to me it seems like a pretty straightforward argument that the collapse cannot happen through decoherence. I've only dug out one random paper that mentioned this argument with very little subsequent referencing of it.
The results of nonlocal and nonrealism theories come out the same, though nonlocal theories imply a lot of mysteries around the contradiction between instant communication and relativity of simultaneity, while nonrealism just paints a picture of a MWI universe that's surprisingly larger than our expectations.
No one has postulated a "conscious measurement operation" with additional useful effects beyond the measurement defined in textbooks. (Well, okay, Roger Penrose says things that kinda sound like that, but that's pretty fringe and beyond the scope of quantum mechanics.) In fact, there's literally no known experiment that a person or a machine could perform that would distinguish a "conscious measurement" from the usual mechanical measurements quantum computers use. That is the sense in which consciousness has nothing to do with measurement.
IMO quantum mechanics really doesn't have anything to say about consciousness that wasn't already present in classical mechanics. Instead of saying "but how can an assemblage of gears experience an outcome" we're saying "but how can an assemblage of superposed gears experience an outcome". It's just the same hard-problem-of-consciousness confusion dressed in new clothing.
Putting on my baseless assumptions hat, it seems to me the world just behaves as a weighted average of all possible pasts, that reality isn't "branching" into many worlds on measurements so much as just being a giant vector space of electron states that have some discrete gaps in an otherwise continuous space due to precise measurements being made, and that the phenomenon of particle-wave duality is just an artifact of some rounding the universe does under the hood when averaging together these possible pasts to render a given state*, and that any attempt to understand the casuality of the particles will fail because they don't arrive from a single cause, but a space of causes, which we can at best constraint to single points.
It's a convenience to explain states within equations. When you say "the cat is both alive and dead at the same time", you're simply saying "in this equation, do not assume that this variable will be one or zero, calculate the results for both conditions", and the final outcome will possibly be one of these calculated results.
The more such variables you have, the more different results you may get.
These concerns remained theoretical until the 1960s, when physicist John Bell devised a way to test if reality is truly spooky—or if there could be a more mundane explanation behind the correlations between entangled partners."
[...]
Such “Bell tests” have since been carried out, with a series of watertight versions performed in 2015, and they have confirmed reality’s spookiness."
Logic:
If you believe that the Bell Test is correct -- you must equal-and-oppositely believe that the speed of light is NOT the upper limit of speed in the universe, that is, that Faster-Than-Light (FTL) speeds are possible.
Conversely, if you believe that speed maxes out with the speed of light, and that nothing can travel faster than the speed of light -- then you equal-and-oppositely believe that the Bell Test is wrong.
But, you cannot believe that nothing can travel faster than the speed of light AND that the Bell Test is correct, simultaneously -- as this would result in a logical paradox...
(Choose one, but not both at the same time...)
This is precisely why the experiment was proposed, to show this conflict in our understanding of the constraints.
That's how I mentally think about entanglement. I doesn't need to operate through the universe as I understand (or operate within) it.
That's not exactly correct, you just have to forgo locality, which some interpretations of quantum mechanics do, like the Bohmian one. Like the sibling comment points out, this still doesn't permit faster-than-light communication.
Er, yes, but, forgoing locality -- changes the definition of speed -- because it changes the definition of distance:
Speed = Distance / Time
If you forgo locality, then you are now able to modify distance in this equation, that is, your equation now looks like this:
Speed = ((Distance * NON_LOCALITY_SCALING_FACTOR) / Time)
That's because, let's say you have a black hole/quantum entangled particle/stargate/thing A at one point in the universe that immediately influences thing B at some distance to it in the universe (call this "connected" concept by whatever name or metaphor you will), etc.
Well, if so, then the NON_LOCALITY_SCALING_FACTOR is there to adjust the shorter distance to the longer one.
Like let's say you had a stargate linking two points in the universe, and you walked 10 feet into it, but this 10 feet, after you had walked it, resulted in you appearing halfway across the universe.
OK, so that's 10 feet in local movement, in local distance, but billions of miles of actual (but non-local) distance.
That's why you now need NON_LOCALITY_SCALING_FACTOR in your equation, because you've redefined Speed in terms of it.
But, by redefining Speed (which must occur, by forgoing locality!), you now have agreed (because it is implied) that anything faster than light (communication, travel etc.) can now occur, that is -- all you need is a high enough NON_LOCALITY_SCALING_FACTOR in the equation for speed -- which you get by forgoing locality...
The collapse still propagates at the speed of light across the bridge.
All the experiments become much clearer if you think of everything behaving primarily as a wave (all possible paths are taken). A particle is just a special (limited energy) case of this where all paths are still taken but since there is limited energy only one path can be 'registered', and this happens probabilistically.
The superposition collapses way before the cat is affected, when more than a handful of atoms is concerned, way before the hammer even moves.
At at any moment, there might be some n number of waves that are the highest. But not until the exact moment you measure the answer exists.
The intent of the thought experiment was to show that the Kopenhagen Interpretation of quantum physics is ridiculous. In the many-worlds interpretation for example there is no paradox, as time goes on more and more worlds exist where the cat died at some point.
1: https://en.wikipedia.org/wiki/Double-slit_experiment#Other_v...
I'm likely wrong in details here, but isn't that thought experiment similar to "what happens at the origin when we draw a hyperbola" sort of question? (Nothing happens, as you can't draw a complete hyperbola.)
If that line would be in the beginning, I would not have bothered to read the article :/