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Reimagining of Schrodinger's Cat Breaks Quantum Mechanics -- and Stumps Physicists (nature.com)
In a multi-'cat' experiment, the textbook interpretation of quantum theory seems to lead to contradictory pictures of reality, physicists claim. New submitter Lanodonal shares a report: In the world's most famous thought experiment, physicist Erwin Schrodinger described how a cat in a box could be in an uncertain predicament. The peculiar rules of quantum theory meant that it could be both dead and alive, until the box was opened and the cat's state measured. Now, two physicists have devised a modern version of the paradox by replacing the cat with a physicist doing experiments -- with shocking implications.
Quantum theory has a long history of thought experiments, and in most cases these are used to point to weaknesses in various interpretations of quantum mechanics. But the latest version, which involves multiple players, is unusual: it shows that if the standard interpretation of quantum mechanics is correct, then different experimenters can reach opposite conclusions about what the physicist in the box has measured. This means that quantum theory contradicts itself.
The conceptual experiment has been debated with gusto in physics circles for more than two years -- and has left most researchers stumped, even in a field accustomed to weird concepts. "I think this is a whole new level of weirdness," says Matthew Leifer, a theoretical physicist at Chapman University in Orange, California. The authors, Daniela Frauchiger and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich, posted their first version of the argument online in April 2016. The final paper [PDF] appears in Nature Communications on 18 September.
Quantum theory has a long history of thought experiments, and in most cases these are used to point to weaknesses in various interpretations of quantum mechanics. But the latest version, which involves multiple players, is unusual: it shows that if the standard interpretation of quantum mechanics is correct, then different experimenters can reach opposite conclusions about what the physicist in the box has measured. This means that quantum theory contradicts itself.
The conceptual experiment has been debated with gusto in physics circles for more than two years -- and has left most researchers stumped, even in a field accustomed to weird concepts. "I think this is a whole new level of weirdness," says Matthew Leifer, a theoretical physicist at Chapman University in Orange, California. The authors, Daniela Frauchiger and Renato Renner of the Swiss Federal Institute of Technology (ETH) in Zurich, posted their first version of the argument online in April 2016. The final paper [PDF] appears in Nature Communications on 18 September.
Is this just another way of saying "Number 7 will shock you!"
"I think I can safely say that nobody understands quantum mechanics."
A physicist in a superposition of feeder and food states until the refrigerator is opened?
Aren't the physicists in the box collapsing the function already by observing the coin? Unless we are saying that the system would behave like nested functions where the internal function collapses when the internal observation is made and a secondary function that includes the 1st one as a variable also collapses when the external observer performs their observation.
We replaced the cat with Folgers Crystals. Let’s see if anyone notices.
In the world's most famous thought experiment, physicist Erwin Schrodinger described how a cat in a box could be in an uncertain predicament.
Compared to the second most famous, but ironically similar: "Does this dress make me look fat?"
Where your relationship is also in an "uncertain predicament" -- being both dead and alive -- until the question is answered.
It must have been something you assimilated. . . .
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so. It's not about the whole cat decaying. The experiment is that if a geiger counter detects a single atom decaying it triggers the release of a poison to kill the cat. Thus the quantum state of the single atom determines the life or death of the cat.
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I don’t think it’s possible to KNOW precisely at any given moment whether quantum mechanics is broken, and to what degree it IS broken if indeed it is. That’s kind of the point of quantum mechanics.
OR...
If a mechanic breaks your quantum, he should have to fix it, theoretically.
I cant decide which joke to go with, so I've decided on a quantum superposition of both:
If don’t mechanic it’s your to he preciesly have any fix...
Hehehehe... quantum humor... simultaneously both really funny, and not funny at all, but you won’t know WHICH it is unitl you read the joke and collapse the wave-function.
Our reign has gone on long enough. Indeed. Summon the meteors.
...but only if you believe in it, like Tinkerbell.
Finally the ultimate class separation, into those who can believe in magic and those who cannot.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
I say we just leave the physicists in the box and go get a beer.
If the cat were dead, you'd be sure to smell it.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
The whole point of Schrodinger's cat experiment was to show that trying to apply certain quantum physics theories to reality resulted in absurd results.
To him (and Einstein), it was obvious that the cat could not be both alive and dead, and therefore the people pushing the superposition theory were obviously wrong.
It's a shame that his thought experiment has been taken to mean the exact opposite of what he was originally talking about.
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so.
No, the whole point was to point out the absurdity of the Copenhagen interpretation. Unfortunately, most people tend to miss this part and think that Schrödinger espoused the point of view that he was actually arguing against.
I never understood how it should work when the cat is a conscious observer anyway.
This is even worse. That and I could easily, with two modern qbit AI processors and a quantum entanglement network card, duplicate this experiment. One would think physicists are living in the far off future world.....of 2003.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
I am not sure if I completely understood the paper but I think the problem is about so called coherences.
In quantum mechanics a particle can be half in spin up and half in spin down. But it can also be minus one half in spin up and plus one half in spin down. The negative sign stems from the quantum coherence. The probabilities for each case are still the same to find the particle in the respective state. It used to be thought that an observer of the particle could also be regarded to be in such a coherent state. And that it didn't matter that to him it didn't look like it, but for him it looked like nature had already decided on an outcome.
It turns out that this isn't the case. Either the quantum state was already collapsed by the observer or not. The views are incompatible and lead to disagreement. The paper constructs this explicit disagreement.
If scientists can't agree on this will it be a cat fight.
"That's the way to do it" - Punch
Most physicists don't give much credence to the Copenhagen Interpretation. There are better ways to think about quantum mechanics.
https://en.wikipedia.org/wiki/...
Everybody believes it will change the world, but nobody can show proof of how.
It is a cat.
When the cat wants to be in the box, it is in the box.
When it wants to be out of the box, it is out of the box.
Death of cats is expressly prohibited under the Rules of War.
Now, parrots or songbirds, those are ok.
-- Tigger warning: This post may contain tiggers! --
No, the whole point was to point out the absurdity of the Copenhagen interpretation. Unfortunately, most people tend to miss this part and think that SchrÃdinger espoused the point of view that he was actually arguing against.
And the Copenhagen interpretation is the new "Bohr atom model" - almost no one believes it this century, but it's still widely discussed and often taught in intro-level classes, out of simple tradition.
Anyhow, measurement devices collapse the wave state, removing this sort of uncertainty at the point of measurement.* It was never a very good thought experiment in the first place. The fact that you can't scale up quantum uncertainty to the macro scale in any straightforward way is the answer to SchrÃdinger's question.
* That's usually explained very early on even in describing "quantum weirdness" in lay terms. The two slit experiment stops giving a diffraction pattern as soon as you measure which slit the photons/electrons/whatever go through.
Socialism: a lie told by totalitarians and believed by fools.
Schrödinger's point about the cat thought experiment is that that cat is NOT in two separate states at the same time. That was his expressing his aggravation about the contradiction of the results of his work and reality.
The question remains, "How does potential get resolved?"
Until we open up Schrödinger's coffin, we can't know whether he was arguing for or against the Copenhagen interpretation.
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Applying a cat to the interior space of a box usually results in you bleeding ... a lot.
But doesn't the cat count as an observer?
I am not a physicist, but the whole thing always seemed ridiculous to me because of that. And now we replace the cat with a physicist. The physicist must count as an observer, meaning the vector state collapse all happened long before anybody else even though about opening the box.
Schrodinger's Cat is just a thought experiment. The rules of quantum mechanics don't apply to large scale things like cats.
Applying Schrodinger's Cat to physics itself does not actually change physics.
You are severely underestimating the role of thought experiments in QM. Seriously study the history of it and how people like Einstein reacted to some of the interpretations.
99.9% of QM is the plot of a bad sci-fi movie, indistinguishable from divining reality by reading cat guts, and the rest is math. Apparently this is acceptable because it pays for further research.
If someone is talking about QM and it’s not about math, it’s bull shit. Forget all about the weird personifications of random things, immeasurability because almost (always unsaid but read between the lines) divine reasons, it’s BULL SHIT.
Things are immeasurable because they are really fucking small and we are big, that’s QM for Idiots.
There are macro-scale quantum mechanical effects, like superconductivity and ferromagnetism.
This isn't to detract from your point about the cat, though. You're right.
They should call this the Xzibit Effect.
Because yo dawg, we heard you liked measuring the quantum state of experiments, so we put some experiments in your experiments so you could break the rules of quantum mechanics. I mean, so you could experiment while you experiment.
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so. It's not about the whole cat decaying. The experiment is that if a geiger counter detects a single atom decaying it triggers the release of a poison to kill the cat. Thus the quantum state of the single atom determines the life or death of the cat.
Except if there was a cat in a box with a valve and pipe and container of gas and a relay to a geiger counter and some isotope...
Everything would be interacting with everything, and there's no physical uncertainty. Just you not knowing until you look.
Much of quantum physics crap today is fundamentally the "If a tree falls in the woods and no one is around to hear it, does it make a sound?" question. If the tree falls it's already interacting with shit. If you can even KNOW that the tree is there, then it's interacting with shit.
it's still widely discussed and often taught in intro-level classes, out of simple tradition.
... and ironically, it is often taught by people that denigrate creationism.
https://foundations.ethz.ch/wp-content/uploads/2018/04/renner.pdf
Surely the quantum state collapses as soon as the state of the particle is measured. It's measured as soon as it affects things at a macroscopic level, not when someone looks at the measurement. So the cat is not simultaneously dead and alive. It's one or the other. Even without the cat, the geiger counter will have measured the state.
Schrödinger's Cat isn't science. It might be considered mathematics, logic, or philosophy, but science requires falsifiable predictions, and Schrödinger's Cat doesn't make any.
It would be neat if it can be logically disproven, though, then it would be science fiction.
The two slit experiment stops giving a diffraction pattern as soon as you measure which slit the photons/electrons/whatever go through.
as soon as you measure which slit the photons/electrons/whatever go through.
as soon as you measure which
you measure
measure
...You sure you understand what the weirdness is?
Populus vult decipi, ergo decipiatur...
"Force shits upon Reason's back." - Poor Richard's Almanac
Yeah, but I thought the point of the thought experiment was to point out the problematic nature of quantum mechanics-- because the cat isn't actually be both alive and dead at the same time.
Whether the cat is alive or dead is a problem of incomplete knowledge, not of an uncertain quantum state. The box is sealed so we don't know whether the cat is alive or dead, but it is either alive or dead. If the geiger counter is measuring the decay of an atom, that counts as a measurement. We can put other equipment in the box to record when the geiger counter was triggered and when the cat was killed. We still won't know whether the cat is alive or dead while it's sealed, but we can go back to the recording and determine whether it was alive at a given moment.
This is in contrast to theories about quantum mechanics which state that there actually is no outcome until it's measured. It's not just that you don't know where the photon is until you detect it, but the photon doesn't exist in an exact location until it's detected.
At least, that was my understanding of the thought experiment.
I'm also not understanding the modified version of the thought experiment proposed in the article. It says that Alice can, "using her knowledge of quantum physics — prepare a quantum message to send to the other friend". What is a quantum message in this context? Then it says:
I don't understand that, since it says that the information would be transmitted in a "quantum message". But apparently you need to know the "quantum properties" of the person in the other box?
Because he could be spinning in his grave in either direction. (sorry).
Where are we going and why are we in a handbasket?
Did they just find the Godelian loop of QED?
I think one question about whether the wavefunction has collapsed/decohered or not is whether the answer to that is subjective or objective (Does the answer depend on who's/what's observing and what their state of information/entanglement with various things is?)
Without being able to crack the math and physics of the new thought experiment (I'm not at that level), I feel that the new paper is poking around that question.
How does it come to be (or why does it have to be, or DOES it have to be) that when quantum systems get measured and collapsed, by various "independent" observers, that the result is a single consistent complex classical state.
How does that happen? Does it always happen?
Where are we going and why are we in a handbasket?
I think they're trying to talk about boundaries across which things have NOT been interacting (in a quantum-state destructive way) yet.
No matter how complex the thing inside a boundary is, you could in principle (t least in a thought experiment) have the whole thing not entangled in any way with the observer and their entangled environment. So can that complex but isolated thing be in a quantum state/superposition, FROM THE PERSPECTIVE of the outside observer?
I suspect that was the idea of the box concept.
Where are we going and why are we in a handbasket?
This just seems like a reiteration of the Many world interpretation?
https://en.wikipedia.org/wiki/...
So is this more scientists arguing about the 2&3 polarizing filter Bell's theorem example?
You know the one where 2 linear filters at 90 block a photon 100% of the time but if you add a third filter in between the two at 45 they all block the photon ~47% of the time?
Like is this a Local Realism thing?
Or is this more of a "what constitutes an observer" question?
Didn't get your point, sorry.
Socialism: a lie told by totalitarians and believed by fools.
... different experimenters can reach opposite conclusions about what the physicist in the box has measured.
Einstein introduced us to the fact that the universe can appear very different from different points of view. For example, if explosions of supernova "A" and supernova "B" occur, it may be observed that "A" occurred before "B", or that "B" occurred before "A", depending on where the observation was made. Either observation is equally valid, even though the conclusions are logically opposite.
Once one accepts the notion that physical observations are "relative", why is it so shocking that quantum mechanical observations might also be logically opposite, depending on who is observing?
I believe you are mistaken.
Schrödinger’s point was that the Copenhagen Interpretation led to absurd conclusions. See below.
https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat#Origin_and_motivation
Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics. However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real. Intended as a critique of the Copenhagen interpretation, the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics.[citation needed] Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.[citation needed]
I think the premise is flawed; specifically, I don't believe that "wavefunction collapse" is a thing. Wavefunctions are wavefunctions, and when you convolve them with other wavefunctions you can end up with peaks and valleys in different spots. When you observe a wavefunction, you're just convolving it with yet another wavefunction, ad infinitum. There is no collapse.
Yes, but everything I've read about this in the past few years suggests that the simplest explanation is that the Geiger counter acts as the "observer" and "collapses the wave function" which determines at that point if it'll release the poison or not. From the Geiger counter (and the cat's) perspective, the cat is either alive or dead. All of this quantum weirdness goes away when the wave collapses, which means the particle (or pair of entangled particles) interacts with something else.
"I have never let my schooling interfere with my education." - Mark Twain
Cats have 9 lives.
This is because making a "measurement" some magic processes that collapses a wave function is utter bullshit.
You do not need to be just a cat or a human. The box is an information consumer, so is the air and everything else within it.
Well, these physicists are going small scale. In the book Quarantine, everything is a quantum superposition.
More exactly, life on earth somehow evolved the trait of being able to collapse quantum waveforms. What if it wasn't normal, and most intelligence in the universe actually existed in a smeared quantum superposition, so had to quarantine earth off to protect themselves?
Err, yeah.
Let's see if I have this straight. Quantum physics is in an undefined state between valid and invalid and we must wait for a cat to resolve the state? Is that roughly right?
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
I thought the purpose of Schrodinger's cat thought experiment was to illustrate the absurdity of the Copenhagen interpretation. So, now the new thought experiment is again reinforcing original thought experiment... that you can have two different conclusions?
The entire concept of an analogy is that it isn't exactly like the thing being described, but in certain ways certain things are similar.
If the actual concepts were simple enough to describe in a way they would be understood, you wouldn't need an analogy in the first place.
Quantum mechanics is ultimately math. Math that takes numbers in and gives numbers as a result.
When applying those numbers to reality, the math turns out the same solution as we observe in reality.
Most people hate math. Despise even basic math. Showing one of those people a math formula that pops out the answer is both 1 and -1 isn't going to make things any better.
How that math relates to reality is even complex, and there is nothing at our scale of existence that works the same to compare it to.
Thus using an analogy. People understand what a cat is, so mapping 1 and -1 together as the answer to a cat being alive and dead together.
It lets people who don't want to hear the math get the gist that there are two solutions, both equally correct, yet both seemingly so different that even scientists are baffled how it could be.
It is as confusing as a cat being two different things, alive and dead, at the same time, when clearly that shouldn't be.
The second you apply anything to an analogy outside of the limited basic scope of comparison as you did will 100% throw you off the rails arguing details that don't apply to the real thing using aspects of the analogy that were never similar or related in the first place.
You go on about observations and atoms and cats can't do that when the one and only thing that analogy is used to explain is that the solution to the equation is both 1 and -1
I have looked at the article's text. The key assumption, which I would say is bullshit, is on Page 3.
> Assumption (Q) is that any agent A "uses quantum theory."
We simply don't know if an agent, which is a quantum-mechanical system, can use quantum theory. I.e., whether the quantum theory contains a useful non-trivial model of the part of itself which is relevant to the experiment described in the article.
thought,thinking and even thinking on the subject is deadly
This indicates that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner
So, coarse-graining still applies?
Your description would seem to favour the totally observer-subjective viewpoint. As the information converges (that is, more and more entangled things are measured together), there is a more and more constrained and complicated wavefunction, with many very particular peaks and valleys, and very rapidly less remaining uncertainty in state description.
But still, could there be two inconsistent versions of all that, held by so-far-not-entangled observers? When those observers finally compare notes, by convolving their models of what's out there together (becoming entngled), it's interesting that that comes out to a single consistent classical state estimation.
Or maybe it isn't interesting. Maybe it's just the way that math (convolution of wavefunctions) has to work, and whatever that says, that's what you get, and somehow "of course" that's a consistent description of classical reality.
Where are we going and why are we in a handbasket?
I think that the description is one of those things that's absurd in a way that makes people pause, but doesn't seem to trigger the thought that was intent to be conveyed. To most people, they're still imagining that there's a cat in the box, and being alive or dead doesn't matter because they imagine the cat about the same way. Maybe there's some other part of what does it mean to be both alive and dead at the same that makes their mind stray into philosophical territory that doesn't matter.
I think it was Einstein who used a similar metaphor only with a barrel of gunpowder that could either be set off or left alone. When people imagine an exploded barrel of gunpowder, the mental image is completely different than that of a barrel of gunpowder and it's easier to say that it doesn't make sense to say that a barrel of gunpowder is both states since they're so vastly different. With a cat, the cat is still there and its form hasn't really changed. It still looks the same and could be mistaken for sleeping perhaps.
It seems to me that much of the 'weirdness' of quantum physics comes from the complexity of mathematics that are meant to allow for a possible range of unknown values (aka probability fields).
So, what I've never been able to understand is this. Just because we are unable to know both the position and speed of a particle, why is there an assumption made that the particle doesn't have both a position and speed?
I guess the point is it seems like most of the 'weirdness' stems from the assumption that the model is a complete and accurate description of reality.
Why do people assume that?
I'm not well educated on some of this but I'm trying to learn.
Thanks for patients ahead of time.
âoeTolerance applies only to persons, but never to truth. Intolerance applies only to truth, but never to persons.
The simplest solution is many world theory, an unfortunately named theory ... there are no worlds, just an infinity of myopic interpretations of the wave function by some deluded parts of it.
Let me get this straight, when the box opens does the cat see Schrodinger alive or dead?
I mean, whatever contrived radio active decay a poison trigger nonsense the cat has to put up with also applies to Schrodinger.
Ahh, the old determinism debate - does God roll dice and if a tree falls in a forest does it make a sound?
Quantum mechanics (and thermodynamics for that matter) are useful mathematical models rooted in statistics. They are extremely useful tools but ultimately not exactly how our universe works. A true model that infallibly predicts all actions would need to take into consideration the state of all matter and energy in the entire universe. Obviously this is utterly impractical for we mortal beings, so statistical models are the best we've got - and they are plenty good enough as long as we understand their uses and limitations.
P.S. Everything is a wave, de Broglie was pretty much right.
Greed is the root of all evil.
And the Copenhagen interpretation is the new "Bohr atom model" - almost no one believes it this century
A 2011 survey of attendees of a conference on quantum physics would disagree with you, with 42% of the respondents (a plurality) listing the Copenhagen interpretation as their favorite interpretation of quantum mechanics.
Anyhow, measurement devices collapse the wave state, removing this sort of uncertainty at the point of measurement.
Sorry -- what's your definition of the Copenhagen interpretation? Because, to my understanding, wave function collapse on measurement *is* the Copenhagen interpretation: "Here's the quantum regime. Here's the classic regime. The result of a 'measurement' is always classical. -- How do you go from quantum to classical? It doesn't matter, it just does. We have well defined procedures to extract the empirical (classical) measurement results from a given quantum result. Throw a black box over the 'how', then shut up and calculate."
Schrödinger got his initial idea from a correspondence with Einstein.
Albert said that if the Copenhagen Interpretation presented by Niels Bohr and Werner Heisenberg were correct, a barrel of gunpowder is, at the same time, exploded and not exploded.
In agreement with that derisive point of view, Schrödinger came up with the cat paradox.
Both paradoxes have long been resolved by pointing out that objects as complex as barrels and cats are macroscopic.
Quantum mechanics applies on the microscopic scale and, to some degree on the mesoscopic.
Experimental physicists are trying to understand precisely where the delineation of scale is.
Meanwhile one-off thought experiments like this 9ne are plentiful.
It little behooves the best of us to comment on the rest of us.
You are correct.
And, by "measurement," we don't mean "humans looking at it."
The "measurement problem" was settled long ago in that there are a shit load of "measuring devices."
When a quantum interacts with anything , that's a measurement.
It little behooves the best of us to comment on the rest of us.
The whole point of Schrodinger's cat experiment [phys.org] was to show that trying to apply certain quantum physics theories to reality resulted in absurd results.
No, it is more subtle than that. It was designed to show that one interpretation of the results of QM was wrong by showing that it leads to an absurd explanation for every-day scale objects like cats. Nobody ever believed that the cat was in some weird superposition: that was indeed the entire point. The interpretation of QM, called the Copenhagen interpretation, was clearly wrong which is why nobody believes it today. However, everyone believes in quantum mechanics itself and that it works when describing reality (it's the second most precisely tested scientific theory that has ever existed). The problem is trying to get brains that are used to a world that works in the large-scale limit of QM to really grasp the rather different underlying reality.
If you throw a tennisball behind you, then quantumtheory states that it can be eanywhere behind you, but it is when you turn around and look for it, then you can decide where it is?
To call this science, is stupid.
The mathematical equation are still used. What your itnerpret them as MW, copenhagen wave collapse , or angel on a pin is pretty much unfalsifiable. Among my colleague copenhagen is still the majorly used interpretation , just look at QM article they speak of measurement and collapse. Not other world or angel on a pin.
C. Sagan : A demon haunted world:
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Of course it's right. Clearly we can't rely on a physicist is resolve it, and cats are well known for having a definite opinion on everything.
I heard this argument in undergrad physics. And honours physics. I even heard it in a postgrad level physics course I took (QFT).
Quantum mechanics applies at "micro" scales but magically vanishes at "macro" scales.
What I have never seen (but would love to see) is a solid, mathematically backed explanation of *how* or *why* it vanishes.
If you believe that, you haven't taken a single course in quantum mechanics. Copenhagen interpretation is still taught as the orthodox interpretation of quantum mechanics—maybe everyone has an issue with the whole idea of non-local collapse of wavefunction (or what makes up a "measurement"), but it's more widely believed than any of the other cooky theories, including some that Einstein proposed.
https://www.xkcd.com/955/
Anyhow, measurement devices collapse the wave state, removing this sort of uncertainty at the point of measurement
Yeees. And it only requires probability wave states that "collapse" at literally infinite speeds... nothing can possibly go wrong with this final, slayer-of-all-others, supreme, holy "interpretation", no-seree-bob, nothing, I tell ya!
You have to trust cats; they've been working on gravity experiments for centuries. I'm sure there's an ancient Egyptian scroll out there detailing a cat who throws all the stuff off of a table.
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so. It's not about the whole cat decaying. The experiment is that if a geiger counter detects a single atom decaying it triggers the release of a poison to kill the cat. Thus the quantum state of the single atom determines the life or death of the cat.
No. Seriously, no.
The whole point of Schrodinger's cat thought experiment was to mock the absurdity of the likes of Heisenberg. Much like Zeno's paradoxes, it was meant to get you to start thinking critically about the situation at hand, instead of applying arbitrarily rigid rules.
Yes, Schrodinger was trying to get you to think outside of the box.
The "measurement problem" was settled long ago
LOL. No it wasn't. The one glaring unexplained "feature" of the "collapsing wave state" idea is that the "collapse" is required to occur at infinite speeds, at any distance. A measurement of one entangled particle is required to instantaneously affect the other at the other end of the universe.
This "interpretation" is just as wonky as all the others, just in its own unique ways that appeal more to its true believers. Polls conducted amongst quantum physicists show that a significant percentage does not subscribe to your "long settled" model. They have others.
The truth however is that no-one has come up with an "interpretation" of all the empirical data that is both comprehensive and internally consistent and does not include wee little "oopsies" like infinite speeds or backward time travel or what have you. We have fragments of models, most mutually incompatible.
So far quantum phenomena defy our best efforts at comprehensive model, there are just many more and less fashionable "ideas" for such a model that show "promise". Nothing more.
Most people also believe that 'observation' is the universe caring about human consciousness.
...you forget that I personally find the Many Worlds interpretation distasteful. Therefore it is false.
Telling, is that you provide no citation of a poll.
I'm in this field (see what I did there) and science is not not a democracy wherein a 51% majority settles matters.
The wave collapse is instantaneous across any distance because the quantum measured is a single object (a wave).
There is no "information," transmitted during collapse, and therefore, no violation of the speed limit of light in a vacuum.
It little behooves the best of us to comment on the rest of us.
Can someone who understands QM tell me why physicists are not jumping at the idea that these QM effects like in the double slit experiment or quantum tunneling are caused by the world being a simulation at a certain resolution which governs most actions. Once we âzoom inâ(TM) (measure something on that small quantum scale) an additional rendering takes place which would produce other results. Like in a low resolution 2 bodies might seem to overlap, which in a higher resolution would turn out to be false. Parallel to quantum tunneling seems uncanny to me, but my level of understanding QM is very low.
Thus the quantum state of the single atom determines the life or death of the cat.
An atom is a gigantic object in the quantum level. Treat it as classic.
Let's see if I have this straight. Quantum physics is in an undefined state between valid and invalid and we must wait for a cat to resolve the state? Is that roughly right?
It's not even wrong!
When a quantum interacts with anything , that's a measurement.
That is simply the only explanation possible for the meaning of measurement. I've been saying this for years. Thank you!
Even at the quantum scale a given particle resolves to a specific state. I would say a particle is never in a superposition of multiple states. The only thing that is in a superposition is the wave function which yields the probability for particle to be in a given state.
When you calculate the probability for a particle to go to a new state you multiply the probability amplitudes unless the new state can happen in multiple ways and in that case you add the probability amplitudes. The case where you add the probability amplitudes is where you get the superposition (wave interference), but this is an interference of probabilities not the particle itself.
Assuming random numbers don't exist, the new argument falls apart.
You're confused.
General relativity addressed how space-time behaves in a gravitational field.
Special relativity describes the effects of velocity in differing frames of reference.
You are also mixing classical physics with quantum physics.
You have some of the vocabulary in your toolbox, but I'm afraid that's the extent of your understanding.
I suggest you read more.
That's what it takes.
It little behooves the best of us to comment on the rest of us.
"The peculiar rules of quantum theory meant that it could be both dead and alive, until the box was opened and the cat's state measured."
I think maybe why everyone is finding so many strange side effects with this thought experiment is that it is based on a premise that it is fundamentally flawed.
Unless you're a hooker, there is no such thing as being dead and alive at the same time. You are either dead or alive... measuring the situation simply tells you the state you are in, and have probably been in for a while.
FFS the linked article didn't mention the original paper, thank goodness they even mentioned the authors. After tracking down the authors publications, I have located the original paper on arxiv. It's interesting to read, and seems to lend more thought experiment evidence to the many world interpretation.
Sorry.
You're mashing up the wave theory of the double-slit experiment that includes interference with wave collapse.
Superposition is another thing outside all that.
We are working hard on superposition and the jury's still out.
It's speculation and hard to prove because measurement causes decoherence.
It little behooves the best of us to comment on the rest of us.
As a lay person with an engineering background, I find QM to be exceedingly weird. All our intuition stems from interaction with the classical (macroscopic) stuff around us. Trying to extend it to the quantum world is rather frustrating.
I recently took up an opportunity to attend a few lectures on introductory quantum mechanics, just to see if I can develop some intuitive understanding of quantum mechanics. My key takeaway (please correct me if I am wrong) was that in the quantum world, measuring a quantum state and interacting with a quantum state are the same thing and will almost always modify the state being measured.
There were a host of other concepts which were introduced but most of them appear to boil down to this essential difference.
Muahaha! Oh this is precious. When cornered, feign "authority"! "Hah, look at me, don't you see my fancy hat?! I am a Doctorus Maximus at an Imperial Academy of Mysteries Arcane! How dare you not follow our Codex of Words most Portent to the letter! You are polluting my presence, pleb! Guards!"
Gods, dude, General Relativity is directly determinant of maximum speed of information transfer, Special Relativity is a consequence of General Relativity, hence, clue, one of them is called "General". Dictionary. Get one.
Special Relativity was developed earlier and then expanded into its final form, which covers more and deeply the workings of the universe. I mean, this is just hilarious, that you would try to literally puff yourself up with righteous gravitas after such a blunder. I am laughing myself silly here.
As to the unholy act of "mixing" quantum and classical physics, that's the fucking point! The blasphemy belongs to virtually any bloke in search of the Grand Unified Theory since, like, the advent of elemental particles! I am starting to suspect that you are a phony. Otherwise you would have known that the unresolved disparity of the macro and sub-atomic physics is the fly in the soup of physics that literally every "move-over Einstein" wannabe has wet dreams about and that the most basic pre-requisite of any solution is that the models do not contradict each other! Duh.
That is also how one disqualifies incomplete and wrong models. Hint: they do contradict. Who would have thunk it?!
Information theory is my stock in trade and silly physicists have been dabbling in my turf for a while now. Mind you - none of them bother with our specific terminology either - and frankly I don't give a fuck because what matters is concepts and not labels.
And transmitting "information" (and in fact what constitutes "information") is apparently not your strong suit. Surprise.
But this grandiose "go back to school" cop-out when unable to defend your obviously losing argument is a timeless Internet classic. My hat off to you.
P.S. Your school assignment: figure out what constitutes "information" in a context of any physical system (hints: state, change). Bonus points: how "information" and its "transmission" does not require an "observer" or a "purpose".
Than we will talk.
Orthodox. When a physicist uses that word he is pointing up the element of faith involved, and probably implying that he doesn't believe it.
There is around a dozen interpretations (what does it mean, really?) of quantum mechanics.
I remember reading a while back about a convention where they took an anonymous poll of which interpretations the attendees favoured. To everyone's surprise Many Worlds was the most popular.
Schrodinger's Cat is just a thought experiment. The rules of quantum mechanics don't apply to large scale things like cats.
Applying Schrodinger's Cat to physics itself does not actually change physics.
Even if quantum mechanics didn't average away into nothing at that scale, the thought experiment still requires to pretend you don't know what an "observer" is, and that you don't know that every atom of the Cat is an observer already. The "observer" isn't the physicist after all, but rather it is the photon detector; and the cat is large enough to be interacting with everything else in the box just by its presence. And even if that was not so, as soon as you press the button the waveform has to either collapse or not, or else the cat wasn't affected. The cat is only used as an anthropomorphic small object; you're asked merely to care about the object, in order that it is easier to understand how impossibly non-intuitive quantum behavior is.
There are two morals to the story: 1) Photons are neither particles nor waves, those are just metaphors that have predictive value under narrowly defined circumstances. Attempts to explain it intuitively lead directly to nonsense like this thought experiment. And 2) Sub-atomic particles make awful pets. You can't even know if they're hungry or if you fed them at the same time.
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so. It's not about the whole cat decaying. The experiment is that if a geiger counter detects a single atom decaying it triggers the release of a poison to kill the cat. Thus the quantum state of the single atom determines the life or death of the cat.
This sort of explanation is exactly why people are better off without these "thought experiments" that purport to simply the matter.
In the experiment, the cat either died or didn't, and if it died is besides the point. Certainly there was no mystery in a random data source being tied to a switch that had consequences. That's not even close to the point! The real point is that if it was a cat, the waveform collapsed or didn't right away, because the probability of each atom in the cat being in the same position relative to its neighbor is very very high compared to the a probability normalized to be close to 50/50. Meaningless. It only has meaning if the cat was actually not an observer, rather than trillions of observers as is the case in the real cat; and that is the actual thought experiment. If the cat wasn't an observer, it wouldn't be alive or dead until you opened the box, and then when you did the waveforms would collapse to one state or the other. The whole point is about when you can know the result, not about what happened.
And it is well established experimentally that if you really didn't interact with it, it wasn't actually in a state yet! So doing the same thing with multiple things just increases the number of things that have to be prevented from interacting in order to get the sort of quantum result being discussed.
Copenhagen interpretation is still taught as the orthodox interpretation of quantum mechanics
Perhaps in some of the more backward, remote realities, but it has long been abandoned in the more sophisticated worlds.
You seem to be caught up on this speed of light problem. stop caring about speed of light. It is causality that matters. If something cant cause something else, then the universe don't give a shit when it happens.
Absolutely. How else?
Interesting. Reminds me of Gödel's incompleteness theorems: any consistent system of axioms contains statements that are unprovable within the system. Equally mindblowing in a way: the Gödel metric
"You must try to forget all you have learned. You must begin to dream." -- Sherwood Anderson
Iâ(TM)m on the other side of the country, and I mail you a package. You open the package and you find out it contains my left shoe.
Haha
stop caring about speed of light ... it is causality that matters. If something cant cause something else, then the universe don't give a shit when it happens.
forget speed ...cant cause... Hmmm.
"Err, when I pushed this button on the thingy the wave collapsed and now I got a particle..."
Oops.
"Admiral, we are done, the cypher code has been transmitted, our ends of the pairs of entangled particles are set, waves collapsed, the 2nd Fleet has theirs being now precisely the reverse..."
Ooooops.
I guess speed does matter when you consider if the "wave collapse" model violates General Relativity after all..
Oh you are too funny. You don't set the ends you measure them.
Good trolling though, would read again.
Every macroscale object is a bit fuzzy. For humans and cats that's just the radius of one electron orbital on the outermost atoms. But for an individual atom or electron, that's a relatively large radius.
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
So the function of the Higgs field is to recycle the universe. This will happen when we observe the Higgs particle.
If by that you mean physicists, you may be right. If however, you mean intelligent (that may caveat this) people, bullshit. I've argued with that interpretation right here.
Oh you are too funny. You don't set the ends you measure them.
Gods, you set them by measuring them and thus collapsing the probability waves into their correspondent particles.
This in fact is the very foundation of quantum key distribution idea where one side of the transmission measures their particles first and knows their collapsed states, by definition when the other side measures them they will be the opposites, also see under: entanglement.
You have no clue, do you? Now who is trolling whom?
Bell's inequality is basically there's an experiment you can run before checking which shoe is in there, and you get one range of results based on superposition of both, but if you open the box and see the left shoe, now you get a different answer, which suggests there is neither a definite left or right shoe in there before you look.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Einstein didn't want to give up on locality (speed of light as a limit) nor reality, which is to say definite objects out there with real, measurable properties.
If you move to "we're a simulation" or quantum mechanics itself is built atop a lower "reality" of the above type, then Einstein gets sad.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Exactly the same level of weirdness, but for people who didn't get it previously and thought they did.
I would have used the word "mainline", but that's the word that David J. Griffiths uses in his Introduction to Quantum Mechanics.
I'll grant that interpretations of quantum mechanics still remains controversial, with the Bell's Theorem being the last meaningful progress on this topic (yes, this is counting the paper that was just published). Who knows why Many Worlds interpretation is as popular as it is; it's probably more a symptom of the problem that is the difficulty of giving an interpretation to quantum mechanics that is consistent with the laws of universe (locality, etc.).
This isn't the point you think it is man. Sorry.
Duplex relationships between human concepts is not the same thing as supporting evidence for human concepts.
Sure there's no proof that there's no deity, and sure we can't look outside the universe to determine whether one is currently watching us. That's explicitly not the same as proof there is one.
Seriously? I hope that means you are at best a first-year graduate student. Because if that meant anything else (like, heavens forbid, if you are a PI or something), NSF has seriously failed us.
Wavefunction collapse is believed to be non-local despite all the problems it causes, because to be otherwise is to allow for possibility of non-conservation of conserved quantities (most notably angular momentum, which is the most popular way to entangle quantum states). It's not because "the quantum measured is a single object", whatever the hell that's supposed to mean.
That is simply the only explanation possible for the meaning of measurement. I've been saying this for years. Thank you!
Except it is wrong, of course. If it were true, the double-slit photon counter experiment could not work since the waves would either always collapse or always stay as waves by always interacting with the counter apparatus irrespective if it were counting or not. The attempt at actually counting the photons is what changes the outcome. If you disconnect the counter output (leaving it in place) the pattern changes. This is no simple "interact with ANYTHING" behavior.
FTFY
https://motls.blogspot.com/2018/04/frauchiger-renner-trivial-to-see-that.html
I have read a lot of popular science and it often seems to gloss over a lot of issues. So I can't really comment till I've done some more reading.
But the cat in the box experiment drew me to some conclusions, and raised a lot of questions.
A summary of my thoughts (which can be thought to be completely wrong by those in the know, I am in my own belief box at the moment): follow.
For something to be as big as a cat described entirely by a quantum wave form, the box must be impenetrable to everything being emitted from inside. ie the box itself must undergo no measurable transformation what ever happens inside the box. This would have to include gravity as well if any quantum gravity theory would emit information depending on the result of the first nuclear breakdown.
So if two impenetrable boxes somehow become combined lets pick another word "entangled" then the wave form to a "wave form calculator" (not an observer yet) would now need to cover both internal states of the boxes.
And you are now back with the one box scenario (though in the case in the article there are now two observers).
However there always seems to be some confusion or glossing over what an observer actually is. It could be a particle or some people even seem to suggest that it needs a conciosuness, but I think that is a bit of a stretch. I consider an observer to be anything that is instantaneously interacting with an object described by a wave form from it's point of view, as soon as it does this it has become part of the wave form from another external observer. But it now has special knowledge of the internal state of the wave form. Effectively it has "climbed in the box".
On a cosmic scale this seems to indicate that the parts of the universe that are beyond where light can travel from by now (due to expansion of the universe) are in one massive wave form, Until a single photon leaks out to give information about a past state of the wave form. The wave form collapses and a new wave form is born.
If there really is a dispute about what is in the box after two observers have measured it, then there really is something weird going on, as it would have to mean that quantum entanglement is partially broken, which would then solve the a paradox as the two boxes would appear to have but never entirely entangled themselves.
No doubt the many worlds interpretation may say that the combined boxes are from two "different worlds" so that they can give inconsistent results when individually measured.
My 2 pence worth. But I know I am wrong about a lot of the details here.
The whole point of the Schrodinger's cat thought experiment was that quantum physics can apply to large scale things like cats and people, indirectly, if you design a mechanism to make it so. It's not about the whole cat decaying.
It does no such thing as you go on to admit.
The experiment is that if a geiger counter detects a single atom decaying it triggers the release of a poison to kill the cat.
Which completely fails to describe quantum anything applying to "large scale things". The cat was never in a superposition of dead or alive.
Thus the quantum state of the single atom determines the life or death of the cat.
Wrong. Collapse of the quantum system influences the life or death of the cat.
name the real-world benefits of quantum theory. There's PLENTY of scientific theories with tons of real-world applications that have real effects on humanity, but quantum physics just 'aint' in that list - so you need to temper your enthusiasm for this mental masturbation. It's the sort of thing one off the most useless branches of academia (theoretical physics) gets all excited by, but it sure is NOT one of the "most successful theories of the physical universe".
The Schrodinger's Cat thought experiment was a tool Schrodinger used in an argument, but it was never really that good for anything else (it was not of equal value to an Einstein thought experiment)... after all the superpositional state of the particle did not really matter to the cat - what mattered was the real-world effects of the particle and since the real-world effects posited in the experiment are NOT quantum states themselves, there's no real situation in which the cat both dead and alive, there's just the ignorance of the observer about the cat's condition before he opens the box to check (the cat is at any moment actually alive or dead and NEVER both), not that it matters because the entire field is on par with a beer-fuelled college bull session.
Bonus points to the person who just realized that the pop culture (and theoretical physics) fascination with Mr S's imaginary cat is completely misplaced and stupid.
It was never about the cat. It was never about a mystical cat-based situation. It was Schrodinger attacking a stupid argument with a silly example.
Many worlds makes quick work of this whole thing. Referencing original explanation, 3 subsets of multiverse: AA,AB & B. In subsets starting with A, Alice in her box sets up spin sideways, in B, spin down. In AA, Bob measures spin up, in AB & B, spin down.
The contradiction is supposed to be in AB Alice is in superposition to Bob, but not to herself. But in many worlds, everyone was always in AB, but they couldn't know that until diverging from copies of themselves in parallel worlds, which they only do when information about choices occurs. It's all beautifully consistent.
-The art of programming is the pursuit of absolute simplicity.
That kind of reasoning is called "sophistry". The fact remains that the "wave collapse" model violates General Relativity. Note that in the General Relativity model nothing can travel faster than light.
Restriction is on moving thru space. If you are able to change something without moving thru space relativity means jack.
No. Nothing means nothing, no exceptions. A ginormous, universe-spanning, "wave" cannot collapse at an infinite speed without violating General Relativity. Period. Even if it does so in a way that somehow precludes an outside observer from transmitting "useful" (to him) information through this process. The information "useful" to the universe would have been transmitted just the same, at speed infinite.
Best to think of quantum systems as a transaction protocol within a gigantic parallel supercomputer. All evolution of system from it's initial state is executed by the protocol which ensures global consistency.
The only real thing is the computer executing transactions. Nothing else actually exists. The computer doesn't give a shit about space and time or whatever "useful" means. It only cares about evolving the system. Rules are executed by the computer. The computer itself is not subject to them.
Well, the original Copenhagen thing referred to an "observer" and everybody jumped to the absurd conclusion that it must be a conscious human observer. As opposed to a cat, or indeed a Geiger counter.
These days, only popular science-mangling magazines (and some stupid schoolbook authors) still perpetrate that both-alive-and-dead-superposition nonsense.
If you disconnect the counter output (leaving it in place) the pattern changes
Is this actually true?
CLI paste? paste.pr0.tips!
"could be both dead and alive"
Nope. Equal probability does NOT equal both states at the same time.
Yes, it would actually be quite delicious. ... few chunks of meat in there, some mushrooms, parsley add wine and lots of cream ... thicken with a light roux. Serve with fresh garlic bread and a glass of wine. ...
Reduce it to a quarter
Gotta go ... forgot I had an appointment at the animal shelter.
That's the reason she's asking that question.
Have you never learned to communicate on an emotional level? (Where the words don't matter, but only how you say things, and how it feels. It’s the main language of women and not that rare in men either [e.g. when they're angry].)
Or, if you don't love her, grow a spine, and leave. ... [the "dead" part] ... and you "love" her anyway, please get a therapy and leave her.)
(If she treats you like this
I don't understand what big problem people seem to have with this. You're a man. Act like one.
(I'm a man, by the way. But I don't act like "women can't be understood" or "men are dumb" so I can be lazy or trampled on.)
You are in a slave-master relationship. That you were told is marriage, but isn't. Just like your anticipatory subjection is not love, but makes you talk yourself into a fake feeling that compensates your fear.
A marriage is an equal relationship. That's your job just as much as hers.
Maybe you're just too afraid of being alone. I preferred being alone to being in what you call "marriage" though. It's the smaller pain.
Wikipedia hath said it. That's enough for me.
Is this unique to the Copenhagen interpretation? Does the same problem exist in Bohmian mechanics?
What if the Physicist Farts in There?
Gods, you set them by measuring them and thus collapsing the probability waves into their correspondent particles.
Shades of Scorpius! All you silly hoomans are missing the big picture; The cat isn't in the box. The cat isn't alive or dead or both at the same time. The box doesn't have a vial of poison and a scientific apparatus in it. The box doesn't have an inside, an outside, sides, edges or corners.
Here's the point: There is no cat! There is no vial of poison, or a box, or an experiment, or a quantum waveform, or a thought. What the fuck happened to all the Buddhists we planted on this bass-ackwards node?
And for Relativity Dude up above in the comments: Ok, fine, if you insist on seeing "things" everywhere, then all these things are ideas, and since there is no distance between two ideas in the consciousness, there is no violation of causality when you "collapse the waveform" (i.e. when the idea that there is a waveform and that it has collapsed arises in the consciousness).
Posting AC because we're not supposed to short circuit the process like this, but at this point, I think all you flat-earthers have pretty much fucked yourselves anyway. I'm just going to go grab some popcorn and enjoy the rest of the shitshow. Toodles!
^This^ Everything can be fuzzy.
That is the point. Everything has a fuzzy wave function. It's just that some are essentially zero; macroscopic ones being zero.
It's called the Quantum Zeno Effect; a watched state cannot change. A cat is a giant system that watches itself, so it remains
a cat.
QM craziness all boils down to the fact that you cannot know the speed and position of a particle at the same time. It's in the
Heisenberg Uncertainty Principle given by the equation regarding the uncertainties (sigmas) in position and momentum.
sigma(position) * sigma(momentum) => hbar/2 .
Given this equation, it's a priori really because
momentum = mass * speed.
And
speed = delta(x)/delta(t).
For you to know a particle's position exactly, delta(t) goes to zero, resulting in a division by zero. Division by zero has no
meaning, so our uncertainty of the speed must be large; whence the equation. Think about it this way. If I know that
something is in a particular place, the I can ask if it was there yesterday, the day before, or even years before, resulting
in a large time t. The problem is that in the macroscopic world, we pretend that we can see objects and know their position exactly
HAVING FOLLOWED THEM OVER TIME. In the microscopic world, we CANNOT FOLLOW PARTICLES OVER TIME
w/o CAUSING A MEASUREMENT, and thus fixing either of the position or the speed. I know this sounds muddled, but
it's just a problem of taking things to the microscopic world where it's hard to "watch" a single particle over time without
destroying the experiment. The implication is that the particle and/or space itself is indeterminate (i.e. Fuzzy) at the quantum scale.
Copenhagen interpretation is still taught as the orthodox interpretation of quantum mechanics
Perhaps in some of the more backward, remote realities, but it has long been abandoned in the more sophisticated worlds, Marty!
When a quantum interacts with anything , that's a measurement.
That's not quite true. When a photon diffracts off the edge of a slit, that's not a "measurement", i.e., you get a diffraction pattern, even though it changes the path of a photon (similar for the interactions that cause photons to move slower through glass).
IMO that's the problem with the Copenhagen interpretation in the first place - the idea of "measurement" is too sketchy.
Socialism: a lie told by totalitarians and believed by fools.
Because, to my understanding, wave function collapse on measurement *is* the Copenhagen interpretation:
Was trying to say: " the Copenhagen interpretation is wrong, but even in the Copenhagen interpretation, Schrodinger's cat doesn't work".
Socialism: a lie told by totalitarians and believed by fools.
I'd agree with him: the entangled pair of states is a "single object". Can't think of a better way to say it in English. |Up Down > is a "single object" as is " |Down Up>. That's how you get cos^2.
Socialism: a lie told by totalitarians and believed by fools.
Yeees. And it only requires probability wave states that "collapse" at literally infinite speeds... nothing can possibly go wrong with this
Non-causal effects can "move" faster that the speed of light. If you shine a flashlight at Mars, then flick it over to shine at Jupiter, the place you're point at "moves" faster than the speed of light, but not in any interesting way, right? The only thing "moving" FTL is some human's focus of attention.
This is why I don't like the Copenhagen Interpretation: this notion of "wavestate collapse" as an actual, physical thing, rather than just a human construct for understanding the problem.
Socialism: a lie told by totalitarians and believed by fools.
Comment removed based on user account deletion
No.
Either direction? There are 3 axes of spin, so he could be spinning in 6 different directions. And don't even get me started on the combinations.
The Quirkz Handbook of Self-Improvement for People Who Are Already Pretty Okay
If Gods are an anthropomorphism, is this a digitalmorphism?
it could be both dead and alive, until the box was opened and the cat's state measured. Now, two physicists have devised a modern version of the paradox by replacing the cat with a physicist doing experiments -- with shocking implications.
So now there is a living and dead physicist doing experiments inside the box? Are they trying to create zombie science?
If i understand the paper correctly, then the gedankenexperiment could be interpreted as a "double slit (#include "obviousjokes.h") experiment with scientists".
In the double slit experiment a particle (e.g. photon, electron) is aimed through a plate with two slits (a,b) at a screen. after repeating the experiment many times one will see an interference pattern. Notably some regions of the screen stay blank, according to quantum theory (QT) no particles can end up there.
The way QT works we need to consider the paths of the particle through both of the slits (i.e. path A, path B), behind the plate there is interference between those two possibilities which determines the probability that a particle ends up on a spot of the screen (including probability zero in some region). The interference breaks down once one determines (measures) which of the slits (either a or b) the particle has passed. In that case there will be no interference pattern and the particle may end up in one of the spots the interference pattern leaves blank.
There are different "interpretations", what it is that "interferes", in the many worlds interpretation the particle took path A in one world and path B in another, and both worlds interacted to produce the interference pattern. The moment a scientist measures if the particle went through a or b he is in one of the worlds, the other world is excluded and can no longer make interference. Important is, that for the interference to happen the particles must be "isolated" in the sense that nothing happened that could distinguish between path A and path B.
Now instead of a particle they made the gedankenexperiment with scientists complete with a laboratory instead of the particles. The "double slit" becomes a measurement in which the scientist in an isolated laboratory is given a specially prepared quantum state S from which he can measure either result a or result b, instead of the paths there are now two "stories", either A or B to unfold, depending on the measurement. An outside observer then measures not A or B, but superposition states |A>+|B> or |A>-|B> (not normalized). These states are "orthogonal", only one or the other can result, like |a> and |b> are orthogonal, the first scientist can only have one measurement result.
The superposition state is similar to the measurement at the screen of the double slit experiment. It is designed so, that a measurement deciding between |A> and |B> is incompatible with a measurement deciding between A>+|B> and |A>-|B>. If one knows which path was taken (A or B) the interference between both possibilities is destroyed.
Now the first scientist is given a specially prepared quantum state: S=|a>+|b>. After his measurement an outside observer that is isolated from the measurement result will assume for the isolated laboratory the state |a,A>+|b,B>. So the outside observer will always get the result |A>+|B>, never |A>-|B> if the isolated scientist is given this state. The |A>-|B> result is like the blank spot on the screen.
The experiment is extended", by making the quantum state S dependent on a measurement of another scientist in another isolated laboratory. While it makes the story more complicated it is all based on the incompatibility of measuring either in the {|A>,|B>} space or the {|A>+|B>, |A>-|B>} space. QT says you can only get the result of one of those measurements, knowing if |A> or |B> was measured destroys the interference, after that measuring {|A>+|B>, |A>-|B>} is no longer determined by the state S the first scientist started with but on his result. Like in the double slit experiment the interference pattern is destroyed once it has been determined if path |A> or path |B> was taken.
Going from double slit to this gedankenexperiment the paths A or B the particle could take are now replaced by stories A and B about the measurement the scientist did.
If QT applies to the macroscopic syste
"By the way if anyone here is in advertising or marketing... kill yourself." -- Bill Hicks
Technically in quantum physics there are no boundaries.
To him (and Einstein), it was obvious that the cat could not be both alive and dead, and therefore the people pushing the superposition theory were obviously wrong.
It's a shame that his thought experiment has been taken to mean the exact opposite of what he was originally talking about.
Yes, and this is the same reason that in EPR, Einstein posited what amounts to entanglement, to show that "spooky action at a distance" was so absurd that the theory must be garbage. Unfortunately, both Einstein and Schrodinger were wrong, and rather than their thought experiments falsifying quantum mechanics, their thought experiments now serve as examples of how deeply weird our reality is.
As has already been pointed out, Bell's inequality shows that you are incorrect. You are just playing semantic games by calling it a "single object". The math shows that two entangled particles have no hidden variables. Their state is only decided upon at the moment of measurement, and you can do all sorts of things to one particle to manipulate its state and find that its partner will mirror it exactly, instantaneously, across any distance. If this is not deeply weird to you, you have not understood QM.
Sounds a bit like a cartoon character questioning the existence of the cartoonist!
Self-importance and self-indulgence is the root of ALL evil.
I said instantly across distance.
It is not a violation of the light speed limit because the action does not involve information.
It little behooves the best of us to comment on the rest of us.
Even if it somehow did, there are measurable state changes on both ends of the longest-ever-chewing-gum-thread that cause information to be transferred at infinite speeds between the ends. So even if you do such ridiculous mental gymnastics, the fundamental problems still wont go away, i.e. information travelling way faster than C.
We live in a universe where such non-local events occur. Pretending otherwise is pointless. The challenge is to explain how causality is preserved (without classical hidden variables). QFT does this, but it's hard to put in English - certainly it would take someone more expert than I at QM to do so.
Socialism: a lie told by totalitarians and believed by fools.
A bit of pedantry that I think is very important: two entangled objects have no classical hidden variables. The wave equation is nothing if not hidden variables - they're just not linearly related to any classical observables.
The wave equation describes state that is always there, and deterministic forward and backwards in time, and evolves linearly. It can only describe that state statistically, because we can't observe it directly. Bell's theorem shows a mismatch between classical hidden variables and reality precisely because the relationship between the state modeled by the wave equation and what we observe isn't linear.
For spin/polarization, the "deeply weird" cos^2 comes from how the "quantum hidden variables" transform to observations.
Socialism: a lie told by totalitarians and believed by fools.
That is not what Bell's Theorem states. It only says that the behavior cannot be explained by only hidden variables. The behavior could still be explained by a combination of hidden variables and the measurement axis.
You shoulda got an art degree instead of wasting time your time with chink lies & madeup "science".
Physicists both proved and disproved Quantum Mechanics. The author's heads promptly exploded after the paper was written.
When the Nature Communications publisher accepted the paper, their head exploded.
Scientific readers and peers, having accepted the paper's faultless QM logic, also blew their tops.
The Nobel committee, having decided to award the Nobel Prize to the (now headless) authors, immediately popped their caps.
Science journalists, interpreted and published the result, and fell over headless.
Readers worldwide saw those stories, thought, "Oh, I hadn't thought about that", and promptly exploded.
The illiterate and uninterested saw the commotion, thought, "hey, that looks exciting, wait for me!", and blew their heads off.
And that was that. Humanity, finally understanding the illogical and absurd Universe they lived in, ended.
I saw your other posts in this thread. If you agree with him, that subtracts from the point he was making, not add. You also don't have an understanding of quantum mechanics (or if you do, you are taking great care to avoid showing it here).
Exactly.
Want to strike fear into the heart of a quantum physicist? Just ask about "The Measurement" problem.
From the article:
"Quantum theory has a long history of thought experiments, and in most cases these are used to point to weaknesses in various interpretations of quantum mechanics. But the latest version, which involves multiple players, is unusual: it shows that if the standard interpretation of quantum mechanics is correct, then different experimenters can reach opposite conclusions about what the physicist in the box has measured. This means that quantum theory contradicts itself."
It may also may mean that a true quantum computer cannot exist because it cannot really actually resolve a problem down to a single solution. (The D-Wave uses quantum annealing, and thus is not a true quantum computer).
Running with Linux for over 20 years!
If you believe that, you haven't taken a single course in quantum mechanics.
Not only have I taken some courses in QM I now give them! The Copenhagen interpretation is taught in the same manner than the Bohr atom is taught: it is a useful toy model to get students used to some of the ideas of QM but ultimately it is clearly wrong as, indeed, Schrodinger's Cat successfully showed.
Well, the original Copenhagen thing referred to an "observer" and everybody jumped to the absurd conclusion that it must be a conscious human observer.
No, nobody jumped to that conclusion they were just left without any guidance as to what an observer was, or was not, and started trying to make guesses that had some vague semi-consistency. You can indeed extend observers to include cats and geiger counters. But why did you stop there? Both are made of atoms so can atoms themselves count as observers? If so everything is observed all the time and, if the Copenhagen interpretation was right, QM would cease to work.
So perhaps not atoms but then where between a geiger counter and an atom do you draw the line? We can make silicon devices at the tens of nanometre scale that can detect charged particles like a geiger counter so do these count? This is why the notion of an observer is a complete non-starter: there is no consistent definition of one.
If you truly teach in a way that puts Copenhagen interpretation in the same box as the semi-classical Bohr model, I feel sorry for your students.
Just as in a particle phenomenology class, you should learn Standard Model as if it is correct (not as a useful introductory model that is soon to be discarded) despite its many problems, Copenhagen interpretation ought to be taught in a university quantum-mechanics class as if it is correct despite its many problems.
It really comes down to this: you can't replace a paradigm—no matter how flawed—with nothing. You need something comparable to replace it with, and other than some vague references to decoherence and/or many worlds (I hope you do your students enough service not to bring up the pilot wave model), there is no paradigm that can replace Copenhagen interpretation.
If, as a teacher, you don't recognize that, I do believe you are doing your students disservice.
P.S. Bohr model is different in that we do have a replacement. Maybe in some classes students don't have the necessary mathematics to understand the solutions to the hydrogen-atom Schroedinger equation, but since a robust replacement exists, we can present Bohr model as a useful toy-model introduction (perhaps to introduce importance of angular momentum).
That's why we gave it a name, "measurement", so that we can put it in a black box and forget about it. It's magic!
P.S. Don't ask us about "dark matter" or "dark energy" either. Or "color confinement". Or "anthropic principle". (Although maybe we should just chuck the last one.)
A bit of pedantry that I think is very important: two entangled objects have no classical hidden variables. The wave equation is nothing if not hidden variables - they're just not linearly related to any classical observables.
No. Sorry to be blunt, but you have misunderstood. You should read this paper, and re-read it, until you have understood the nature of the problem. It isn't that there are no classical variables - it's that hidden variables of any type are provably impossible according to the experimental results. This is why Einstein asked "is the moon there when we are not looking?" Experiment shows that the particles cannot have properties (and therefore cannot be part of reality in a classical sense) while they are in superposition.
Some quotes:
According to the Laboratory Record Argument below, there are no things (elements of reality, properties,
“quantum events”, etc.) the relative frequencies of which could be equal to quantum probabilities.
As this simple example illustrates, no matter whether or not we are able to com-
municate with EPR equipment, the very fact that we observe correlations which
cannot be accommodated in the causal order of the world is still an embarrassing
metaphysical problem.
Causality itself is upended by quantum mechanics. There isn't a classical explanation, and there isn't a comfortable interpretation. Experiment shows that our reality is built on logical impossibilities. Every physicist that has understood this problem has been deeply disturbed by it (Bohr, Heisenberg, Einstein, Pauli, Schrodinger, Bell, Feynman) . It is fundamentally misrepresenting the science to pretend that there's a classical answer (or an easy answer) to quantum mechanical behavior.
No. Sorry to be blunt, but you have misunderstood. You should read this paper, and re-read it, until you have understood the nature of the problem. It isn't that there are no classical variables - it's that hidden variables of any type are provably impossible according to the experimental results. This is why Einstein asked "is the moon there when we are not looking?" Experiment shows that the particles cannot have properties (and therefore cannot be part of reality in a classical sense) while they are in superposition. Since they share properties instantaneously at the moment of collapse, they must share information.
Some quotes:
According to the Laboratory Record Argument below, there are no things (elements of reality, properties,
“quantum events”, etc.) the relative frequencies of which could be equal to quantum probabilities.
As this simple example illustrates, no matter whether or not we are able to com-
municate with EPR equipment, the very fact that we observe correlations which
cannot be accommodated in the causal order of the world is still an embarrassing
metaphysical problem.
Causality itself is upended by quantum mechanics. There isn't a classical explanation, and there isn't a comfortable interpretation. Experiment shows that our reality is built on logical impossibilities. Every physicist that has understood this problem has been deeply disturbed by it (Bohr, Heisenberg, Einstein, Pauli, Schrodinger, Bell, Feynman) . It is fundamentally misrepresenting the science to pretend that there's a classical answer (or an easy answer) to quantum mechanical behavior.
You don't set them by measuring them FFS, you discover them. No information is transmitted by "collapse", just by perfectly normal ways. Nothing FTL happens or non-local happens, Bell's theorem isn't directly relevant. The only part that's different from classical mechanics is that a man-in-the-middle can't generate a duplicate of the signal.
Socialism: a lie told by totalitarians and believed by fools.
You're mashing up the wave theory of the double-slit experiment that includes interference with wave collapse. Superposition is another thing outside all that.
I did not say anything about the double-slit experiment and so I don't know where you got that from. I am talking about the wave function (probability amplitude) that when squared gives the probability of a quantum state. Superposition is the summation of the wave function (probability amplitudes) which is what I am talking about.
Again my point is that the Schrodinger cat does not make sense at the quantum level because as soon as a particle's state interacts its superposition has been lost. So it is strange to think of a cat actually being in an alive and dead state, but it is not strange to think of the probability to go to the dead state. Please let me know if you have evidence to suggest I am wrong, but there is only speculation to support the idea that a particle or system is actually in a superposition of multiple states. On the other hand, what I said about a superposition of probability amplitudes is actual fact.
. It isn't that there are no classical variables - it's that hidden variables of any type are provably impossible according to the experimental results.
That's ... not even wrong? The entirety of modern QM is around the wave equation, which is the state of the universe (or some smaller system in isolation). Bell's theorem shows that classical explanations don't work, but QFT works fine.
Socialism: a lie told by totalitarians and believed by fools.
Considering that cats are in the habit of deciding things for you on their own even above quantum level, it sounds about right.
Ezekiel 23:20
Enough people did jump to that conclusion, otherwise the both-dead-and-alive notion would never have entered the pop-sci meme pool.
In any case, yes atoms count as observers when they interact with the quantum state in a way that determines the state of the quantum system one way or another. How fuzzy that line is depends on the experimental set-up but it's far below Geiger counters, let alone cats.
the idea of applying quantum theory to understanding some characteristic of a thing, with the act of using quantum theory in the creation of the thing.
The transistor was not created based upon quantum mechanics, and even quantum tunneling in more recent semiconductors was not so much designed by theoretical physicists telling people how to make a new thing as it was a case of physics explaining an observed and used thing.
Some say this is a academic matter, but I say it still matters if the cart is in front of, or behind, the cart.
I'd say the modern way of looking at it is that all electrons are "a single object": the electron field. That's really the only useful interpretation any more. Thinking of an entangled pair of electrons as one object or two are just choices of ways to dumb down the problem to think about it easier, but you can't reason too far from such simplifications.
Socialism: a lie told by totalitarians and believed by fools.
The entirety of modern QM is around the wave equation, which is the state of the universe (or some smaller system in isolation). Bell's theorem shows that classical explanations don't work, but QFT works fine.
The problem isn't the theory - the theory is remarkably reliable according to experiment, as well vetted as any idea that has ever existed in science. What you don't understand is that this amazingly consistent wave theory is not the solution to the issue - it IS the issue. It predicts impossible things, and then they are confirmed by experiment. Bell's theorem doesn't rule out classical explanations - it shows that there are only a handful of explanations for QM behavior, all of which logically contradict our understanding of reality. Do you think that we live in a world where a single cat can be alive and dead at the same time? Where real paradoxes occur constantly? No, of course you don't. But that's the world that quantum mechanics proves we live in.
Feynman:
" I think I can safely say that nobody understands quantum mechanics."
Bohr:
"Anyone who is not shocked by quantum theory has not understood it."
I advise you to pay attention to the premier physicists on the subject. If you aren't willing to listen to them, or spend the time to understand the math, you aren't going to get it.
Things are immeasurable because they are really fucking small and we are big, that’s QM for Idiots.
Just occasionally, you actually learn something on the internet.
To have a right to do a thing is not at all the same as to be right in doing it
Just as in a particle phenomenology class, you should learn Standard Model as if it is correct
No you should not. You should learn it as the best, most accurate model of particle physics that we have, how we have tested it and what the limitations of it are. We are talking about a university-level education, not force feeding information at high school. It is extremely important that, near the edges of our knowledge, we do not teach things as "correct" but as our best current understanding and the data and observations that lead us to that conclusion.
It really comes down to this: you can't replace a paradigm—no matter how flawed—with nothing.
I don't - I let the students themselves replace it with their own developed intuition about QM. The Copenhagen interpretation is exactly that - an interpretation. It is not a model or a theory. It makes no predictions and there are no observables. Its only purpose is to provide a framework to try and map our physical intuition of the human-scale physical world onto the quantum world. As such it is a useful crutch to help students get an initial grip on QM by providing a bridge but ultimately, as they become more familiar with QM, they have to discard this crutch and replace it with the intuition they have developed themselves. There is no replacement for it because, ultimately, it is trying to do something that cannot work: you cannot understand QM by analogy with the large-scale world because there are quantum phenomena which have no consistent classical analogy.
Overall you seem to have a school-level approach to teaching physics, not a university-level one. University physics students are generally intelligent, motivated people. They are not scared by learning that there are somethings that we do not yet fully understand nor are they incapable of developing their own models and understanding of phenomena. Physics professors are not some modern-day Moses coming down from the mountain with the Standard Model lagrangian carved into a stone tablet telling everyone that this is how the world works. We are people who piece together models and then spend ages trying to test them to destruction so we can learn how to make a better model and imporove our understanding of the world. It is important that we expose students to the limits of our understanding and how we got to those limits because some of those we teach are going to be the ones who may eventually expand our understanding further.
Do you even know what the Standard Model is? Skipped reading the rest of your uninformed drivel.
Oh, wait. I misread it. In any case, I disagree.
As is your prerogative. However, as I said, your approach is good for schools but is a poor choice at University where we are teaching very close to the limits of human knowledge.
Hot chicks only please. BTW libtards are idiots. Thanks for proving it.
Hmmm, It sounds like I'm arguing with a self-hating transgender woman that likes hot chicks.
Tell me - since we made it legal for you, do you choose to use the bathroom that matches your gender identity?