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Quantum Physics Just Got Less Complicated
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.
"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. :-)
"Transparent" is a shit show that trades on every stereotype going. A man in drag is NOT a transsexual.
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.
<blink>down the rabbit hole</blink>
Seriously guys, we need to drop the copenhagen interpretation already. Pilot-wave theory eliminates the need for quantum mysticism.
"Violence is not the answer. Violence is the question. The answer is yes."
Of course! This clears up everything! Now I understand quantum physics completely!
When someone says, "Any fool can see
Wow, loving all the ACs calling this obvious, who clearly didn't even make it to the abstract! "Such wave-particle duality relations (WPDRs) are often thought to be conceptually inequivalent to Heisenberg's uncertainty principle, although this has been debated."
Clearly, all you armchair physicists need to set those ivory-tower morons straight!
Stephanie is fat or homeley
Dear Coward, you fail at google.
A successful API design takes a mixture of software design and pedagogy.
Heisenberg was walking in a field on a chilly night, looking at the stars, when it came to him.
Really.
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.
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.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
I'd love to read a real comment (yeah, I know, it's almost like I'm new here) from someone who is actually capable of understanding the math here. It would be great to see a reasonable discussion on the actual implications here.
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.
The problem with quotes on the internet, is that nobody bothers to check their veracity. -- Abraham Lincoln
There is a difference between having a competing theory, and proving that two broadly recognized phenomena are actually mathematically equivalent.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
If something gets simpler, the entropy of the universe decreases. It can't happen. It is the law, everything should get more and more complicated as time goes by. Why, the next generation will have easier time to pass Quantum Mechanics I PH304 MWF 10:00-11:30 than I did? Would not stand for it.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
"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.
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)
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.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
Any particular reason?
-=This sig has nothing to do with my comment. Move along now=-
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.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
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. 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!
I'm not sure I see what you did there...
Oh, now I do. Not sure where you're going with this, though..
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.
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 down. Does it mean that all the past results were wrong ? No it simply means that it's a model which is only works within a certain range of parameter (it's good for everyday use - you car) if you need to consider parameters outside this range (space ships, planets) you need a better model (general relativity, etc.)
Note:
- with Newtonian physics we speak about a physicis model. About a model that's used to approximate real-world events. This kind of things only get experimental proof (prediction fits the measured data or not). And will eventually get superseded by a better model which works better including for some corner cases or at higher range, smaller scales, etc. (String theory and such were born as a tentative at a better model than the dichotomy between relativity and quantum mechanics).
- with TFA: it's a bout a *mathematical proof* that 2 different models are really actually the same stuff just expressed in different ways. Take one model, tweak the equations, and you should obtain the other model. It doesn't speak about the quality of the models themselves, just the mathematical links between them. ...but usually, when you have a newer model, that is better experimentally, you usually also need to find a mathematical "link" between the two, an explanation why the old model used to work and only got contradicted in your experiment.
(I fact, the quantum mechanics model has its limitation - what you call "wrong" and what I call "use it only within the range of value where it works the best.
QM works best at predict very small scale phenomena (particles, waves, etc.). QM completely sucks at being useful for anything at the other end of the scale: QM is a piece of shit for astronomy. And vice versa: relativity is good when you consider stars, useless when you consider particles. 2 models, each best at a different scale. And strings being a possible future model that could simultaneously work at both scales.).
e.g.: take the relativity equations, and use them to compute the motion of your car - the level of energy and speed are so small, that all the "weird parts" of relativity can be approximated and rounded to 0, what remains ends up looking exactly like newtonian physics. Newtonions physicics are the same, simply with the relativity parts neglected, because they don't play any significant role at that scale.
Science constantly bases decisions on kinda logical principles until those principles are proven to be wrong.
Newtonian physics looks "kind of logic" because it's a model designed and tested and proven to predict a range of events (reasonable speed, low energy, human-size scale instead of particles, etc.) which happens to match what our monkey-brain have evolved to cope with.
(our ancestrors never had to think about nuclear bombs, supernovae, tunnel effect in electronics, etc.)
That's also why it got discovered first (we didn't first invent relativistic physics and the newtonian as handy simplified formula for some type of problems), because that's what was easiest for our monkey-brain to think about.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
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.
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.
.: Semper Absurda
When did it become the "quantum" uncertainty principle? I'm sure Heisenberg was not happy when we switched to the truncated "uncertainty principle," and even further to simply "uncertainty." But who's the asshole that added a superfluous and nearly meaningless word to an old concept? WHO REBOOTED? AND WHY?
The Admin and the Engineer
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 physics rewrites itself as well. In the wave particle duality, particle like behaviour generally involves STL interactions, and wave like behaviour involves FTL interactions.. In an FTL model of quantum physics the whole of quantum physics is fully deterministic and uncertainty principle can be made to disappear completely (locally) but only in interactions involving extended FTL coherence..
Of course the joke is that it is all academic because physicists don't like their sacred cows being slaughtered.. and the biggest sacred cow of all is general relativity.
Below the speed of light Special Relativity is one of the most accurate theories in physics - above the speed of light..