## Quantum Physics Just Got Less Complicated 197

wabrandsma sends this news from Phys.org:

*Here's a nice surprise: quantum physics is less complicated than we thought. An international team of researchers has proved that two peculiar features of the quantum world previously considered distinct are different manifestations of the same thing. The result is published 19 December in**Nature Communications*. Patrick Coles, Jedrzej Kaniewski, and Stephanie Wehner made the breakthrough while at the Center for Quantum Technologies at the National University of Singapore. They found that wave-particle duality is simply the quantum uncertainty principle in disguise, reducing two mysteries to one.
## Copenhagen interpretation != less complicated (Score:4, Interesting)

## Re:Copenhagen interpretation != less complicated (Score:5, Informative)

In its current, immature state, the pilot-wave formulation of quantum mechanics only describes simple interactions between matter and electromagnetic fields, according to David Wallace, a philosopher of physics at the University of Oxford in England, and cannot even capture the physics of an ordinary light bulb. "It is not by itself capable of representing very much physics," Wallace said. "In my own view, this is the most severe problem for the theory, though, to be fair, it remains an active research area."A little early to "drop it", it seems.

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In other words, it's voodoo mysticism which isn't useful for anything, and the author may or may not be reaching to make his theory look sound?

Because the GP kinda makes it sound like healing crystals, and generally not very useful at all.

When there is "much work to do" on your pet theory before it can explain a lightbulb, maybe your theory is worthless?

## Re: (Score:3)

## Re:Copenhagen interpretation != less complicated (Score:5, Insightful)

and arguably in some sense can't be the way Nature does what it does

citation needed.

## Re: (Score:2)

even if it makes some things easier to understand it's not generally the most useful way to think about QM

Engineers use Newtonian gravity as the basis for their equations because they are more practical than using relativity. Even if this theory were to turn out to better describe the universe, actual work would get done using simpler, good-enough probabilistic equations instead of the deterministic ones, but that wouldn't change the fact that the new theory better explains the total body of observations we have.

and arguably in some sense can't be the way Nature does what it does.

Why would this be the case? Chaotic systems as a class are extremely difficult to calculate, but we

## Re: (Score:2)

WTF is an exponential resource?

Exponential refers to the amount of resources, not the type. It basically means it takes e^n resources to simulate. While the GP left n unspecified, lets assume it is either particles or wave functions.

## Re: (Score:2)

I know what exponential means. Why would you defend his nonsense statement is beyond me.

I didn't. I attacked your nonsense ;)

## So true (Score:2)

## Re:Copenhagen interpretation != less complicated (Score:4, Insightful)

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Think about it - how can a pilot wave communicate which way a particle must take without going backwards in time (i.e. violating the Lorentz invariance)? Imagine that you have a classic two-slit single electron interference experiment. Suppose that the pilot wave theory is true - in this case a pilot wave interferes with itself and electron chooses one path and ultimately hit

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Bell showed that Von Neumann's disproof of local hidden variable theories was flat out wrong.

My understanding is that hidden variables theories can be made to work if reality is non-local. And given that quantum entanglement appears to be non-local, hidden variables should be able to work.

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Non-locality means transmission of information with faster-than-light speeds

No. There is some kind of non-locality which does not imply FTL transmisson of information.The effects in QM are exactly of this kind.

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The violation of Bell's inequalities shows that there are no local hidden variable theories, but there might be non-local hidden variable theories. But in contrast to what you seem to think, non-local hidden variables theories do not necessarily enable faster than light (FTL) communication.

.

## Re: (Score:2)

Seriously guys, we need to drop the copenhagen interpretation already. Pilot-wave theory [quantamagazine.org] eliminates the need for quantum mysticism.

That theories been prove wrong hundreds of times now.

The simplest explanation of why it's wrong is that it's Deterministic. i.e. it's part of the "Clockwork universe" and if that's true, then you do not have free will and we should all just throw in the towel now... oh wait, that's right, we don't have a choice. Don't worry, I know it's not your fault that you posted this though, it wasn't up to you!

Determinism = fail

## Re:Copenhagen interpretation != less complicated (Score:4, Insightful)

While we're at it, the Second Law of Thermodynamics must be wrong because I'd like a perpetual motion machine and conservation of momentum must get temporarily suspended when someone's about to be run over by a truck.

Also, determinism doesn't conflict with free will. Determinism is a concept in physics and free will is a concept in law and philosophy. If you try to contrast them, you'll end up equating free will with randomness: you didn't write your message based on your beliefs which you've formed based on your character and experience (since that would be deterministic), but rather it's the equivalent of "cat /dev/random | strings".

No, but even if it was, it in no way would disprove it.

## Re: (Score:2)

With entanglement, we have an FTL coupling that can't be used to convey classical information.

Why can't we have a similarly knackered stripe of determinism, one which can't be used to shatter the illusion of free will? This would be a kind of determinism where even if you sort of know it's there, it makes no damn difference to your interpretation of local space.

Think big, grasshopper, think big.

## Re: (Score:2)

Yet all the observable data we have is in favor of our free will.

Despite the fact that you can't quote a single item of the so-called "observable data".

## Re: (Score:2)

Seriously guys, we need to drop the copenhagen interpretation already.

Sorry, the geniuses who created quantum mechanics were right the first time. The fact that you find it philosophically objectionable doesn't make it any less valid.

## Re:Copenhagen interpretation != less complicated (Score:4, Insightful)

There's no mysticism in quantum mechanics. It's pretty simple and mathematically consistent. All of the mysticism comes from popularizations of quantum mechanics. Bohmian mechanics is an unnecessary complicated interpretation of the same physical models.

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QM is a solid, reliable and well-tested theory of subatomic interactions, but

only when expressed mathematically.As soon as someone tries to translate the math into words, everything falls apart because words are always vague and have multiple meanings.

## Less Complicated (Score:5, Funny)

## Re:Less Complicated (Score:5, Funny)

I bet you didn't even read the math.

On the other hand, if this discovery can be used to further simplify the just simplified results we can use it recursively until all of quantum physics is reduced to a three-second advertising jingle that anyone can understand.

## Re:Less Complicated (Score:5, Funny)

...until all of quantum physics is reduced to a three-second advertising jingle that anyone can understand.

I've collapsed, and I can't get up!

## Re: (Score:2)

Nope, not even entropy-breaking compression can transpose information from real to imaginary space.

## Re: (Score:2)

What I want to know is if this is going to make things easier during the final exam.

## Pilot Wave (Score:1)

I thought that Pilot Wave Theory answered this "uncertainty"?

## Re:Pilot Wave (Score:4, Informative)

There is a difference between having a competing theory, and proving that two broadly recognized phenomena are actually mathematically equivalent.

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## "tl;dr" doesn't make you look smarter. (Score:5, Insightful)

Clearly, all you armchair physicists need to set those ivory-tower morons straight!

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We've personally dealt with long-time academics who have no real world experience. They'll spew theoretical crap all day long, and those of us who have worked in industry see it for what it is: crap.In CompSci, I would tend to agree with you; and the humanities

docount as complete bullshit, so nothing for them to really get objectively "wrong".But in Quantum Physics? In that domain, the academics overlap 100% with "industry". Sure, you could argue that virtually the entirety of the semiconductor

## So... (Score:2)

Can we say that this new discovery is a Quantum Leap? What do you think, Al?

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## Interesting paper, stupid summary (Score:5, Insightful)

Here we show that [wave-particle duality relations] correspond precisely to a modern formulation of the uncertainty principle in terms of entropies, namely the min- and max-entropies. This observation unifies two fundamental concepts in quantum mechanics. Furthermore, it leads to a robust framework for deriving novel WPDRs by applying entropic uncertainty relations to interferometric models.

So they're looking at it in terms of entropies, and when they do, it resolves a debate about whether WPDRs are equivalent to the Uncertainty Principle AND generates new WPDRs.

## How about someone who groks the math, comment? (Score:5, Insightful)

As to people saying "that's obvious" -- what you can intuit and what you can prove are not the same thing. The only thing prove by a "that's obvious" comment is that the person posting it doesn't have a clue.

## Re:How about someone who groks the math, comment? (Score:5, Informative)

A quantum state of position can be written as a superposition of a momentum states; the position is certain and the momentum is uncertain.

A quantum state of momentum can be written as a superposition of position states; the momentum is certain and the position is uncertain.

That's the duality and the extremes of the uncertainty principle. The mathematics can also show more generally, that the uncertainty in position and momentum is always more that a certain value (Planck's constant).

These things follow directly from the axioms of Quantum theory, Hilbert spaces and any two non-commutative operators. So I really don't see how Quantum Physics "just got less complicated". It's the same as it's always been. Although I've not read the paper yet, maybe that makes more sense.

## Re: (Score:1)

Really, really simplified form from one of the linked articles.

Some specialists in quantum information theory (not their term, but it fits) found that a mild variation of their extremely specialized mathematical models could be used to describe the wave-particle duality concept as another form of the quantum uncertainty limitation.

The classic quantum uncertainty argument is that velocity and position are related features that cannot be known beyond a certain level of combined precision. As you test harder

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## Re:How about someone who groks the math, comment? (Score:5, Informative)

I just had a brief look at the published version of the paper. Unless you work on fundamental aspects of quantum information theory, the actual implication is that some old debate that took place back in the 90s has been resolved. As others have already pointed out, the relationship between uncertainty relations and wave-particle duality intuitively makes sense, but actually coming up with a mathematical proof that the two concepts are equivalent to each other is certainly a non-trivial amount of work. However, this paper does not significantly change our understanding of quantum physics, nor does it allow us to magically find an efficient way to simulate quantum physics on classical computers. It will also not change the way quantum physics is usually taught, as wave-particle duality basically plays no role there (and uncertainty relations are mostly a side remark).

Also, notice that the paper has been published in Nature Communications. Usually, this means that the paper was rejected by Nature Physics (or any other of the "Nature Something" journals), so the authors sent it there instead (BTDT). So we probably have at least an editor (and maybe some referees) who thought that the paper was not as sexy as the press release seems to imply.

## The difference between obvious and proven... (Score:2)

## Re: (Score:2)

## That would violate the second law of thermody (Score:5, Funny)

## Not really news. (Score:2)

I'm not a physicist - and I worked most of this out myself years ago - cf. http://slashdot.org/journal/35... [slashdot.org]

## Re: (Score:2)

What's news is that

an international team of researchers has

provedetc.

## Re: (Score:2)

There's one huge problem with the notion of proof in physics: You never know when your theory might be superseded. You can't make a generalising statement in physics which is essentially formally proven since there is always a possibility that it would be overtaken by a newer one.

So, your cite from tea is pretty meaningless. A 'proof' of this order is noting less than a revised theory, hence my OP

## Re:Isn't that obvious? (Score:5, Funny)

"wave-particle duality is simply the quantum uncertainty principle" gets a "no shit" straight away from me, though I guess a rigorous proof of it is kind of news.

Shhh. Don't make waves. :-)

## Re: (Score:1)

You have a good point...

## Re:Isn't that obvious? (Score:5, Funny)

You have a good point...

it's actually a set of points, but the correct point can't be observed without changing it's velocity.

## Re: (Score:3)

Any particular reason?

## Re:Isn't that obvious? (Score:5, Funny)

I'm not sure I see what you did there...

Oh, now I do. Not sure where you're going with this, though..

## Re: (Score:2)

-1, Whoosh I guess. Nice to see a few people getting it, though.

## Re: (Score:2)

-1, Whoosh I guess. Nice to see a few people getting it, though.

Read it again. You replied to an obvious reference to the uncertainty principle. The joke is now dead. Or is it?

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You folks are the maybecat's maybemeow.

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## Possibly new approach (Score:2)

Ghost universes kill Schrödinger's quantum cat [newscientist.com]

To quote:

"THE wave function has collapsed – permanently. A new approach to quantum mechanics eliminates some of its most famous oddities, including the concept of quantum objects being both a wave and a particle, and existing in multiple states at once."

## Re: (Score:2)

Its all academic anyway. Also non-physicist, working in the field of cutting edge Strong AI. - A piece of maths I was working on turned out to solve the real value roots to imaginary numbers.. Fifteen years later - can point out that the real error is in general relativity, figured out how to rewrite the spatial model to include an absolute FTL frame. (all it requires is a limit rule on the size of physical dimensional time restricting it to quantum scales.)

Once you have an absolute frame model quantum phys

## Science, bitches, that's *how* it works! (Score:5, Informative)

"wave-particle duality is simply the quantum uncertainty principle" gets a "no shit" straight away from me,

though I guess a rigorous proof of itis kind of news.That's how science work. You don't base your decision on the mere principle that it more or less looks kind of logical.

(After all, it only looks "kind of logical" to your *brain*, which has spent the last few million years being optimized to help bipedal monkey survive together in the savanah. Actual science can some time feel "weird" and defy logic, because it defies the monkey-brain logic. - e.g.: the sum of all positive integer is a negative fraction [wikipedia.org])

You do thoroughly prove that by the numbers.

Yes, the double-slit experiment (where single particle behave like waves) strongly suggest that the uncertainty principle is at work (there's not *a signle photon* going through the slits, it's instead a function showing the distribution of the probabilities to pick it up at a certain place).

Now, we have mathematical proof that's indeed the case.

Science: the only place where it's actually correct to spend the time and mental ressource to formally prove that water *is* wet, and fire *does* burn. Because, along the way, you develop mathematical tools which come handy to do more advanced science.

## Re: Science, bitches, that's *how* it works! (Score:2, Interesting)

"That's how science work. You don't base your decision on the mere principle that it more or less looks kind of logical."

Newtonian physics looks kind of logical. It's completely wrong, but plenty of decisions are based on it. Despite that we know is wrong we still use it today because it's incredibly useful.

Science constantly bases decisions on kinda logical principles until those principles are proven to be wrong.

## Re: Science, bitches, that's *how* it works! (Score:5, Informative)

Newtonian physics looks kind of logical. It's completely wrong...

No, it's not completely wrong. It's a model that approximates what happens within an acceptable degree of precision for many, many circumstances. We have another model that adds to it and modifies it, and that model is used for situations where that precision is not sufficient. It's not clear that science is capable of providing certainty of "right" or "wrong" beyond determining whether a model approximates what happens within an acceptable degree of precision.

## Re: (Score:2, Insightful)

It is approximately right, but completely wrong. These are not mutually exclusive. Arguing approximations are perfectly accurate is itself a grave error.

We do use Newtonian Physics, not because they are correct (they are not) but rather because their approximations are within tolerances of certain deviations from accurate.

## Re: Science, bitches, that's *how* it works! (Score:5, Interesting)

"Essentially, all models are wrong, but some are useful."

-George E. P. Box

## Re: Science, bitches, that's *how* it works! (Score:5, Insightful)

It is approximately right, but completely wrong. These are not mutually exclusive. Arguing approximations are perfectly accurate is itself a grave error.

You're abusing the semantics of "right" and "wrong" in a scientific context. A theory or law is "right" if it agrees with observations or predictions to within the accuracy of measurements. It is "wrong" if it doesn't. On that basis, Newtonian physics is "right" over a vast domain of experience, but is "wrong" in situations involving atomic particles or near-light speeds. It is

not"completely wrong" -- not at all.BTW, nobody says approximations are

perfectlyaccurate. That's the same as saying they'reperfect, and that would mean they cease to be approximations.We do use Newtonian Physics, not because they are correct (they are not) but rather because their approximations are within tolerances of certain deviations from accurate.

Again, you abuse semantics. Scientists do not use the word "correct" in the sense of an absolute truth, but rather in the sense of what works to make accurate predictions. Science endeavors to shrink-wrap the tightest possible boundary around "absolute" truth, but does not claim to know what that truth is.

## Re: (Score:2)

One of the great scientific minds of the modern era can say it far better than me.

"John, when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together."

Isaac Asimov - The Relativity of Wrong [tufts.edu]

## Newtonian physics works (Score:3)

Newtonian physics looks kind of logical. It's completely wrong, but plenty of decisions are based on it. Despite that we know is wrong

It's not *completely* wrong.

In fact back then when it was discovered, it was experimentally proven to work within the parameters which were tested.

The reason it was used then and is still used now is that within this range of parameters, it still works. For everyday use, what newtonian predicts is within what is observed. That's a precise enough model.

What happened is that scientists started to consider much more extreme paramters range (higher energy, faster speed). At that point, newtonian physics breaks

## Re: (Score:2)

Newtonian physics looks kind of logical. It's completely wrong, but plenty of decisions are based on it. Despite that we know is wrong

If you phrase Newton's force equation as F= dp/dt (rather than the F=ma formulation in your high-school physics text), it's not wrong. You just need to use the relativistic momentum p.

(Newtonian gravity, however, is indeed wrong. Or, to be more pedantic, it is the first-order term of gravity in general relativity.)

## Re: Science, bitches, that's *how* it works! (Score:2)

A self consistent theory is never "wrong". It can, however, be used incorrectly by applying it to a system that does not follow the axioms. Our universe follows Newton's axioms within experimental error at moderate size and energy scales. At much smaller or larger scales, the axioms no longer describe our universe and as a result the theory no longer applies.

## Re: (Score:3)

"wave-particle duality is simply the quantum uncertainty principle" gets a "no shit" straight away from me,

though I guess a rigorous proof of itis kind of news.That's how science work.

That more about how math works. Physicists did not care that the calculus of infinitesimal was not rigorous; see especially the Dirac-Delta function. It gave them answers that agreed with experiment which for a Physicist is the best proof. http://en.wikipedia.org/wiki/I... [wikipedia.org]

## Re: (Score:2)

Actual science can some time feel "weird" and defy logic, because it defies the monkey-brain logic. - e.g.: the sum of all positive integer is a negative fraction [wikipedia.org])

You do thoroughly prove that by the numbers.

This has nothing to do with monkey-brain logic but with you either not reading or not understanding related wikipedia articles. E.g. this article [wikipedia.org] clearly says "A summation method can be seen as a function from a set of sequences of partial sums to values."

Thus your 1+2+3+4+....'='-1/12 'non-monkey-brain science' actually says that if you apply a certain function (other than standard summation) to map a divergent series to a number that number will be -1/12. Or, to say it in another way, a nice pasttime for

## Re: (Score:3, Funny)

Stephanie is fat or homeley

Dear Coward, you fail at google.

## Re: (Score:2)

Stephanie is fat or homeley

Dear Coward, you fail at google.

Maybe he really *did* find out what she looks like, but considers her way below *his* standards [imgur.com]...

## Re:Lame (Score:5, Funny)

TFS is so stupid there's no way I'm going to RTFA.

Comments like this are like urine stains on the wall next to public urinals. They appear so often and so consistently you'd think there was a contest, where the first one to miss, wins.

## Re: Lame (Score:2)

Someone needs to invent a urinal aiming sticker for /. comments.

## Re: (Score:2)

I think it does exist. It's the word "beta".

## Re: (Score:3)

## Re:Lame (Score:5, Informative)

Maybe you're thinking of The Feynman Lectures (which is college-level)? In Volume 3, Section 2-2 of his lectures, Feynman shows the deep relationship between the uncertainty principle and wave-particle duality. Feynman sez:

Now this property of waves, that the length of the wave train times the uncertainty of the wave number associated with it is at least 2, is a property that is known to everyone who studies them.

## Re: (Score:2)

The name is Blanche, not Blanch.

## Re: (Score:3)

Heisenberg was walking in a field on a chilly night, looking at the stars, when it came to him.

Really.

## Re:Not News (Score:5, Insightful)

There is a wide gulf between suspecting two phenomena are related, and having discovered the rigorous mathematical framework that lets you translate discoveries from one theoretical framework to the other without losing information.

## Re: (Score:2)

the rigorous mathematical framework

Like the one shown in Volume 3, Section 2-2 of the Feynman Lectures of Physics, published 1964?

Now this property of waves, that the length of the wave train times the uncertainty of the wave number associated with it is at least 2, is a property that is known to everyone who studies them. It has nothing to do with quantum mechanics. It is simply that if we have a finite train, we cannot count the waves in it very precisely.

## Re: (Score:2)

Probably not, that sounds like a qualitative observation. How exactly would you use that to translate an arbitrary new discovery about the properties of particle/wave duality into an equally rigorous description of uncertainty properties?

## Re: (Score:2)

The quote I used comes at the conclusion of a mathematical demonstration - here's the link [caltech.edu]. I've now had the time to read the new paper (TFA), and they actually credit Feynman right at the start for having the general insight. Feynman's discussion is for a single uncertainty relation (position and momentum for a "particle" composed of a finite wave train), while TFA is broadly general and cached in terms of the modern entropy-based approached to uncertainty. So I think you're right, in that Feynman's treatm

## Re: (Score:1)

Ah, the intuitive AC. One course in physics and he is light years beyond rabble of academic researchers who have spent their entire careers on these intellectual dead ends.

A Nobel for you, sir! A hear there is one floating around, waiting for the highest bidder.

## Re: (Score:1)

Congratulations on misunderstanding the point of the post. Yes, this was my intuition. Then I gave some explanation of the intuition. Then I gave some congratulations of the people that proved the intuition. I quote "proved" because often people say something has been proved when in reality no such thing has been done. Science does not prove anything correct. Not reading the article indicates that I do not know whether it was an experimental "proof" or an actual mathematical proof. At no point did I insinua

## Re: (Score:2)

## Re:more simplifications and fewer cats, please (Score:5, Informative)

Ok, let me give this a crack.

You build a box. That box contains a Geiger counter, which clicks if it detects the decay of a particle. Because you're a sick, sadistic fuck, you hook up that Geiger counter to a hammer such that if the Geiger counter detects the decay, it engages the hammer to smash a vial of poison, thus releasing it into the box. You then--because, as I said, have issues with sociopathy--put a cat in the box and close the lid. The box is very thick, completely opaque and completely soundproof. You have no way of knowing what's going on inside the box.

You wait an hour. In that hour, you do some maths that shows that there was a 50% chance that the particle decayed, triggering the Geiger counter, which triggered the hammer to break the vial of poison, releasing the gas and killing the cat.

The question becomes: before you open the box, is the cat alive or dead? Or is it somehow...

both?Your gut instinct is to say, "That's stupid. Of course it's either alive or dead. How the fuck could it be both?"

But the thing is, there are certain, non-cat-related experiments that we've done that REQUIRE the answer to be BOTH. Perhaps the simplest (and certainly the one we physicists learn about first) is the double-slit experiment [wikipedia.org]. The basic idea is, you shoot a beam of something (light, gold atoms, DNA, doesn't really matter) at a slit, and it forms a pattern on a wall. It'll form this pattern even if you shoot your particles one at a time. Then, you close that slit and open another one, and fire your beam again. It forms a different pattern.

Now you open BOTH slits and fire your beam. What happens? Well, what you'd expect is to get a pattern that's the SUM of the pattern you get through each slit. That corresponds to the idea that the particles each go through either Slit 1 or Slit 2. But instead what you get is an INTERFERENCE pattern, which can ONLY happen if the particles are going through BOTH HOLES. And recall I said earlier--you get the same pattern even if you shoot your particles one at a time, which means THE PARTICLE MUST BE INTERFERING WITH ITSELF.

So back to the cat: is it alive or dead, or is it alive AND dead? According to the Copenhagen Interpretation, it's both. But that's why the cat thought experiment was devised in the first place: to highlight how RIDICULOUS that was. The crazy thing is that, seventy years later, we don't really have a better interpretation (at least not one that's widely accepted). So until someone builds this possibly-cat-killing box, we won't really know if the Copenhagen Interpretation is right, or whether something even stranger goes on when quantum events get amplified to the macro level.

One final note: practically speaking, there's no way to build this experiment, because of the whole "you have no way of knowing if the cat is alive or dead without opening the box" part. Isolating a system as big as a cat-box from the rest of the universe is not really feasible. You would also have to construct a particle decay detector that did not, itself, "collapse" the waveform of the decaying particle (otherwise the paradox is resolved before you ever make it to the cat).

Hope that was helpful!

## Thanks, next stop - single particles don't interfe (Score:2)

Thanks for taking the time to type that out. It gave me a starting point to learn more, and I learned that if you release particles one a time, each particle makes one mark, one dot. One particle doesn't interfere with itself, and can't because the interference pattern is seen in the density of collisions over an area.

As many of these single dots build up, they tend to cluster around an interference pattern - as if some particles went through one slit, and some particles went through the other slit. Well

## Re:Thanks, next stop - single particles don't inte (Score:4, Informative)

One particle doesn't interfere with itself, and can't because the interference pattern is seen in the density of collisions over an area.

As many of these single dots build up, they tend to cluster around an interference pattern - as if some particles went through one slit, and some particles went through the other slit.

Not quite--and that's really the key element of this whole thing: the particle somehow DOES interfere with itself, because the interference pattern that builds up, just one particle / one dot at a time is DIFFERENT than what you'd get if each particle only went through one hole. Imagine you're up on a ladder, dropping beanbags through a plank with two slits in it (you can cover those slits if you want), and they form a pile on the ground below. If the beanbags can only go through one slit, the pile you get on the ground is a nice mound. If you open up BOTH slits, then what you expect is TWO mounds. If the slits are close enough together, you expect those mounds to overlap, with the height at each spot being AT LEAST AS HIGH as the height you'd see dropping the beanbags through just one hole.

But instead, what you see in the double-slit experiment is that, in between the two mounts, you get spots where there are FEWER beanbags than you'd get dropping them through just one hole. Somehow, instead of getting that 1+1=2, you're finding that 1+1=0. The beanbags are all still there--it's not like they're cancelling each other out.. they're just not all where you'd expect them.

The ONLY WAY to explain this (that we've found so far) is if each beanbag, which, again, you're dropping one at a time, somehow goes through BOTH slits and INTERFERES WITH ITSELF. This is where the idea of wave-particle duality comes in, because the patterns that you see (with valleys where there should be ridges) are similar to what you'd see with water waves or sound waves (sound waves can cancel each other out--that's the whole premise behind noise-cancelling headphones).

So then why don't we just say that photons (and beanbags) are waves and not particles at all? Well, because classical waves aren't "quantal," meaning you can't divide sound waves into discrete, indivisible components. You can have one "particle" of light (a photon). There's no corresponding discrete element of sound. So we say that they're particles after all, and simply adjust our thinking regarding just what a particle is and how one behaves.

## Ah, one slit != one wave (Score:2)

Aha. That is interesting. A set of particles that move/act like a wave is one thing, but in this case one slit doesn't look like one wave, but two slits looks like two waves. Interesting.

## Re: (Score:2)

I think people are moving away from the Copenhagen interpretation to other interpretations such as consistent histories, decoherence, and many worlds. Bohmian interpretation is another option, but I find it inelegant and it doesn't hold too much sway.

Personally, I feel that consistent histories* is the best. In this interpretation, the cat is simply dead or alive. We don't know which until we check, but the cat's state didn't change when we opened the box. Note that whatever is enforcing consistency does no

## Re: (Score:2)

But instead what you get is an INTERFERENCE pattern, which can ONLY happen if the particles are going through BOTH HOLES.

To me, this is one of the most famous physics experiments of all time... but I have never been able to find out how far apart those holes are and at what distance the holes are apart that the single photon stops traveling through both.

It seems to me if the slits (holes?) have to be closer than the uncertainty of the position of the photon then we are dealing with something other than what we call "physical reality". Call it a sort of building block for "physical reality".

Hm?

## Re: (Score:2)

## Re: (Score:2)

Well, the truth is we have the non-locality anyway. Whatever happens which reduces the measurement to a definite result is non-local. And - ofcourse - there has to be something like this. Stil, I am not too convinced by the pilot wave theory, but it is at least an attempt to deal with the inherent problems of QM by trying to create a proper physical theory, not by philosophical bullshit.

## Re: Entropy underlies all? (Score:5, Interesting)

There's a gravity wave experiment in Poland looking at the simulation question. They've found our universe to cheat between the minimum length that would need to be simulated and the Plank length - it's all noise down there where we expected to find signal.

There could also be an undiscovered reason, but the shape of the noise matches to a few sigma that predicted by the 'spherical projection' simulation model, so that's a good place to look.

## Re: (Score:2)

... It just means we probably can't tell if we're in a simulation because we're defining reality as simulate-able.

Our universe being a simulation is certainly an interesting idea.

However I somewhat cringe at the thought of myself running on the equivalent of a 14 yo alien's PC while his mother yells "Come up for dinner

nowor I'll come town and pull the plug!"