I just had a crazy thought

[MohtasaUnique]

I was watching Flatland a bit while I was on break at work, and something occurred to me.

If a 3D object were to place themselves on top of the flatland world, flatlanders would only be able to see perfect cross-sections of where the the 3D form meets the 2D works. With that logic, pressing your hand against flatland would reveal several 2D cross sections. As a visualization, think of putting a paint hand-print on a piece of paper

Notice the thumb and some of the fingers are entirely separated from the rest of the object. Now imagine you have your hand on flatland, and you moved your hand. To flatlanders, the separate objects would still appear separate, but would be moving in syncronization.

So what if this is the explanation for quantum entanglement? What if a 4D object is impressing itself upon our 3D world, and there are some parts that don't make contact because they're raised away from the 3D world somewhere in the 4th dimension. We therefore see several 3D objects, and they appear to move in synchronization.

But then it begs the question, why does it have to be quantum? Why can't objects larger than electrons and neutrinos entangle themselves? If 4D were a real dimension of space, don't you think we'd be able to see many more instances of 3D objects, entirely disjointed, yet still moving together in synchronization? Why is it hard for a relatively large object to exist in a 4th dimension?


Please understand I'm operating on an elementary understanding of quantum mechanics, physics, and the likes. Basically everything I know has been learned off youtube in these fields. If you have an answer or a reason why this topic isn't even worth discussing (based on legitimate experience or sources), I'm fine with that. An answer is an answer, and if it's an obvious one to any novice physicist, then that's good enough for me.

 

[Xolr]

https://www.youtube.com/watch?v=UnURElCzGc0

There Has nothing to do with your question, but it's flatland

Anyway, it's actually a neat idea to think about. I'm in the same boat as you are, learning everything off youtube and a few wikipedia pages. But that doesn't explain things like how simply observing particles can change their state. For example the double slit experiment. Why does simply looking at something change it states? This is quantum physics that can't be explained.

Simply put I think the answer to your question is that distance isn't real. It's more of an illusion.

 

Occam's razor.

Adding another spacial dimension to the universe to explain one phenomenon would be an extreme case of needless multiplication of entities.

It is much much more likely that the postulates of relativity are wrong.

 

[88jayto]

I don't claim to know much about the subject, but I don't think you can apply 2D > 3D mechanics to 3D > 4D theories. They're not the same thing, and different rules apply.

 

[MohtasaUnique]

I don't claim to know much about the subject, but I don't think you can apply 2D > 3D mechanics to 3D > 4D theories. They're not the same thing, and different rules apply.

Flatland is basically a book written to train people's minds to understand the physics of a fourth dimension. It's not like a whole new world where things are new and magnificent and alien. It's simply a new perspective which we're hardpressed to understand how it would look if we COULD perceive it.

That being said, if theories are true, and flatland is a fairly accurate comparison, then the rules are the same, the mechanics don't differ. Physics doesn't change just because we've suddenly gained the ability to detect another dimension of space. The dimension has ALWAYS been there (if it is there), being able to see it doesn't rewrite physical laws.

This is a good video to explain what I'm talking about:
[YOUTUBE]M9sbdrPVfOQ[/YOUTUBE]

 

[Jei jei KK]

But that doesn't explain things like how simply observing particles can change their state. For example the double slit experiment. Why does simply looking at something change it states? This is quantum physics that can't be explained.

You are (mis/not )understanding what "observation" means in a physical sense. In physics, a photon hitting a particle is an "observer" - any interaction between systems will entangle them, and you lose coherence. When a particle is in a decoherent state, it isn't in a superposition, and no interference pattern (or other wavelike characteristics arising from the particle's superposition) will be observed.

Occam's razor.

Adding another spacial dimension to the universe to explain one phenomenon would be an extreme case of needless multiplication of entities.

It is much much more likely that the postulates of relativity are wrong.

I'm going to go on a tangent here but I'll remind that Occam's Razor isn't generally a good guideline when looking for new theories. For example, Gunnar Nordström created a theory to explain gravitation before Einstein's general relativity. His theory was both simple and mathematically sound, the only problem was that reality didn't follow its rules. After it failed to agree with experiments, it was scrapped and only later did much more complex general relativity come, which described gravity as we observe it.

What I'm trying to say is nature doesn't always follow the simplest solution. However, if it turns out that two theories make the same predictions, the simplest one is almost always the "better" one. For example, in 1948 Julian Schwinger, Richard Feynman and Sin-Itiro Tomonaga independently created a relativistic formulation of quantum electrodynamics, and later Freeman Dyson proved that all their theories are the same. Feynman's method turned out to be intuitive, fast, and accurate and nowadays basically no one uses Tomonaga's or Schwinger's equations.

With all that said, quantum mechanics is fairly simple and to really understand it you need to understand the mathematics behind it(basically linear algebra). And yes, it's unpractical and unnecessary to add any new physical dimensions to explain things.

Relativity really has nothing to do with this, since a) quantum mechanics is a non-relativistic theory, b) even quantum field theories only take special relativity into account (they assume uniform non-curved space) and there's no quantum theory with general relativity, and c) information still isn't transmitted faster than c.

So what if this is the explanation for quantum entanglement? What if a 4D object is impressing itself upon our 3D world, and there are some parts that don't make contact because they're raised away from the 3D world somewhere in the 4th dimension. We therefore see several 3D objects, and they appear to move in synchronization.

But then it begs the question, why does it have to be quantum? Why can't objects larger than electrons and neutrinos entangle themselves? If 4D were a real dimension of space, don't you think we'd be able to see many more instances of 3D objects, entirely disjointed, yet still moving together in synchronization? Why is it hard for a relatively large object to exist in a 4th dimension?

Here I had some stuff, but now I think it's really not really explanative at al, so I just left it at the end of my post. I'll just say that it sounds like your vague extradimensional connection doesn't sound at all testable, probably has a hard time explaining any other quantum mechanical phenomenom, and an additional dimension of space sounds really far-fetched and problematic. Fundamental interactions wouldn't really work if the parts existing in another dimension had mass and electrical charge as we know them. Of course, you could make the claim that our physics doesn't apply to parts not in our slice of 3-dimensional Flatland,but at that point it starts to sound more and more like a teapot orbiting the sun.

In short it's pretty much occam's razor like Sythe said, and I feel dumb for writing a stupidly large post.

It sounds to me that you don't really grasp what quantum entanglement is. I don't blame you: I had wrong ideas from Youtube videos and whatnot before babby's first quantum mechanics course! Of course, I could be just not really understanding what you're trying to say. I'm going to try and explain.

Let's decay a pion. You don't even need to know what a pion is, just that it has no charge, no spin and it decays into a electron and a positron (the anti-particle of electron). Spin is a quantum mechanical quantity of particles, and you just need to know that with electrons and positrons it's ½ or -½. We'll call ½ spin up and -½ spin down.

Charge is conserved. Therefore the pion decays into a -e-charged electron and a +e-charged positron. The total charge is still 0, and that's fine.
Spin is also conserved. The total spin should equal 0, so we know that one of the particles will be + and the other -.

i chose this image because it's the only image for this and i can't be bothered to make a better one: the situation will be, after measurements, either as on the top or the bottom half

Let's measure the spin of an electron. We measure it to be -½. Immediately we know that the positron's spin is ½, and if me or someone else did the measurement they'd find it as such. I'm going to simplify and butcher bra-ket notation to try and describe what is going on.

Here's a wave equation** p that describes a particle:
p = 0.4|+> + 0.6|->

What this means is that the particle's spin is undefined. It doesn't mean it's unknown, because that would imply there's a hidden variable theory at play. There's not*** . When we measure the spin, it would turn out to be either ½ or -½, in other words it's state would be |+> or |->. We get a pile of particles, say, 10000, and repeat the experiment. Eventually we have some 4000 measured spins of ½ and around 6000 of -½. This is as expected, since the probability to measure the particle's state as |+> is 0.4, and 0.6 for |->.

In a multi-particle system, the wave equation is simply the product of both their wave equations:

pp = (0.4|+> + 0.6|->)*(0.4|+> + 0.6|->)
= 0.16|+>|+> + 0.24|+>|-> + 0.24|->|+> + 0.36|->|->

You'll see that the probabilities still add up to one, and you can see the probabilities for the four possibilities for the different states.

Entangled systems cannot be described as the product of their individual particles' states: because of spin's conservation the wave equation is drastically different.

(yes I shamelessly stole and translated images from lecture materials)
** technically I'm making a mistake because the probability to find this particle in state |+> would be (0.4)^2, and the probabilities wouldn't add up to 1 in this case, telling us that there's something horribly wrong with the equation since the possibility to find the spin at all is under 100%.
*** this is kind of off-topic, and basically it has been proven local hidden variable theories don't describe nature, and to be deterministic a hidden variable theory should be non-local and there's been no working such theories.

 

I'm going to go on a tangent here but I'll remind that Occam's Razor isn't generally a good guideline when looking for new theories.

Actually it is a good guideline. That you think it isn't is because you are following what is essentially the ptolemaic mainstream of physics -- wherein whenever something breaks they just add a new hypothetical entity to 'fix the problem'. For example now apparently 90% of the universe is intangible untestable untouchable unseeable immutable 'dark matter'. Instead of accounting for their missing force by I don't know, looking at one of the other four fundamental forces, they suppose the universe is full of black icky stuff which adds more gravity. Good idea.

Nature isn't arbitrarily complex. When you propose a hypothesis that assumes numerous unprovable/untestable entities you are engaging in religion, not science.

For example, Gunnar Nordström created a theory to explain gravitation before Einstein's general relativity. His theory was both simple and mathematically sound, the only problem was that reality didn't follow its rules. After it failed to agree with experiments, it was scrapped and only later did much more complex general relativity come, which described gravity as we observe it.

Both theories of gravity are shit. Hypothesizing that space, i.e. the absence of matter, has attributes is a contradiction in terms. You fall so readily into the trap of 'if the math works then the theory is correct.' This is pure bullshit. You can fit a curve to anything. That doesn't mean you understand how it works.

What I'm trying to say is nature doesn't always follow the simplest solution. However, if it turns out that two theories make the same predictions, the simplest one is almost always the "better" one. For example, in 1948 Julian Schwinger, Richard Feynman and Sin-Itiro Tomonaga independently created a relativistic formulation of quantum electrodynamics, and later Freeman Dyson proved that all their theories are the same. Feynman's method turned out to be intuitive, fast, and accurate and nowadays basically no one uses Tomonaga's or Schwinger's equations.

See previous point.

With all that said, quantum mechanics is fairly simple and to really understand it you need to understand the mathematics behind it(basically linear algebra). And yes, it's unpractical and unnecessary to add any new physical dimensions to explain things.

Right, you just have to give up finite speed of information transfer.

Relativity really has nothing to do with this, since a) quantum mechanics is a non-relativistic theory, b) even quantum field theories only take special relativity into account (they assume uniform non-curved space) and there's no quantum theory with general relativity, and c) information still isn't transmitted faster than c.

Information IS transferred faster than the speed of light.

Quantum physicists the world over would have you believe that the wave function is a mathematical construct -- that it is not real. But if the wave function is not real, then how can a particle really be in a super-position of states? The wave function IS real, as a description of physical states. In Copenhagen the 'wave function collapse' is, in physical literal REAL terms, the changing of a physical object from the state of being in a superposition to the state of being in a single finite position.

You must understand that the superposition can span over an infinite distance. How can a particle with a superposition that spans all of space snap to a single point, instantaneously, at the collapse of the wave function (a real physical change in state) without information transfer at faster than light speed? It cannot. If the other end of the universe did not know that the wave function had been collapsed then surely it could be collapsed at the other end whilst the 'wave of collapse' was still in transit -- that information having not arrived. But this is unacceptable in quantum. This would ruin the model.

I might add that no one at your university will be able to tell you what a wave function is in explicit non-contradictory terms or whether or not it is real. Don't try to ask them because they will become hostile. No one seems to know what the fuck it is or what the fuck they are doing in quantum but they all get paid for it so who cares apparently? But if you are interested in solving the real and significant contradictions of quantum I would direct you at De Broglie–Bohm. Remember however that if you ever did fix physics the world's governments would fund bomb making with the advances and try to kill everyone. It has happened before.

 

[Jei jei KK]

Actually it is a good guideline. That you think it isn't is because you are following what is essentially the ptolemaic mainstream of physics -- wherein whenever something breaks they just add a new hypothetical entity to 'fix the problem'. For example now apparently 90% of the universe is intangible untestable untouchable unseeable immutable 'dark matter'. Instead of accounting for their missing force by I don't know, looking at one of the other four fundamental forces, they suppose the universe is full of black icky stuff which adds more gravity. Good idea.

Nature isn't arbitrarily complex. When you propose a hypothesis that assumes numerous unprovable/untestable entities you are engaging in religion, not science.

Dark matter was hypothesized because stellar objects were observed to exhibit properties that could be explained if there was more mass around than what is seen. Gravitational lensing was (and is) also observed in between galaxies, where there is very little conventional matter to be seen. The simplest solution to this was to propose matter that doesn't interact through electromagnetism - ie. it doesn't emit or absorb photons, and as such cannot be seen. However, this is very far from untestable, since it would still interact through weak interaction. The problem is that weak interaction is very weak, and finite in range (unlike electromagnetism and gravity, which are both infinite in range). Probable ways to find dark matter would include creating it with particle accelerators or collision detection.

I'll also add that weakly interacting massive particles aren't at all weird: neutrinos are extremely common observed particles that interact only through gravitation and weak interaction.

Of course, it could be that some day a better theory for gravitation will be discovered that doesn't need dark matter to explain observation. However, it will have to also explain the phenomena that general relativity does (e.g. gravitational time dilation, redshift, gravitational lensing, orbital decay)

Both theories of gravity are shit. Hypothesizing that space, i.e. the absence of matter, has attributes is a contradiction in terms. You fall so readily into the trap of 'if the math works then the theory is correct.' This is pure bullshit. You can fit a curve to anything. That doesn't mean you understand how it works.

I don't know what to tell you if you think that a theory which has provided working predictions and technology based on it for nearly a hundred years is shit! My point wasn't that if the math works then the theory is correct, as I did provide an example of Nordström's theory which has beautiful mathematics but doesn't at all produce predictions that agree with observations. General relativity does, ergo, it is correct within its realm of applicability.

Information IS transferred faster than the speed of light.

Quantum physicists the world over would have you believe that the wave function is a mathematical construct -- that it is not real. But if the wave function is not real, then how can a particle really be in a super-position of states? The wave function IS real, as a description of physical states. In Copenhagen the 'wave function collapse' is, in physical literal REAL terms, the changing of a physical object from the state of being in a superposition to the state of being in a single finite position.

You must understand that the superposition can span over an infinite distance. How can a particle with a superposition that spans all of space snap to a single point, instantaneously, at the collapse of the wave function (a real physical change in state) without information transfer at faster than light speed? It cannot. If the other end of the universe did not know that the wave function had been collapsed then surely it could be collapsed at the other end whilst the 'wave of collapse' was still in transit -- that information having not arrived. But this is unacceptable in quantum. This would ruin the model.

I might add that no one at your university will be able to tell you what a wave function is in explicit non-contradictory terms or whether or not it is real. Don't try to ask them because they will become hostile. No one seems to know what the fuck it is or what the fuck they are doing in quantum but they all get paid for it so who cares apparently? But if you are interested in solving the real and significant contradictions of quantum I would direct you at De Broglie–Bohm. Remember however that if you ever did fix physics the world's governments would fund bomb making with the advances and try to kill everyone. It has happened before.

I was referring to classical information, which doesn't travel any faster than c. Because the state into which the system will collapse is still random, a measurer will not be able to know which state he will measure a particle to be in if the interval between measurers is space-like.

I bolded the part which is exactly as taught to us. Mathematically wave function in quantum physics is a solution to Schrödinger's linear differential equation. It describes the particle completely, and in Copenhagen interpretation superposition is simply when the particle's state is undefined and will exhibit wavelike properties. This wave-like nature of particles is an experimentally verifiable fundamental property of nature.

I took a look at De Broglie-Bohm interpretation and it seems like it ultimately isn't useful since it also gives only probabilistic results that are exactly the same as Copenhagen interpretation's, but is in addition unnecessarily more complex. Also, it supposedly makes advancing to relativistic quantum field theories (which are in modern particle physics the current best model describing a lot of things) needlessly difficult, but that's another thing.

Basically what I'm saying is if two theories disagree then the one that produces the right predictions is more correct than the other, which should be obvious. In the case that two theories give the same predictions, neither is more "correct" per se but usually one of them is either always simpler or sometimes simpler. For example, there is no reason to use Lagrangian mechanics to calculate how far a puck on ice travels before it stops, since Newtonian mechanics is much simpler in this case. Of course, it is possible to use Lagrangian mechanics to figure it out, but it's much more work for the same results. Any arguing about which of them is more "correct" as a depiction of reality is largely semantics and philosophy, and has no place in physics.

 

Dark matter was hypothesized because stellar objects were observed to exhibit properties that could be explained if there was more mass around than what is seen. Gravitational lensing was (and is) also observed in between galaxies, where there is very little conventional matter to be seen. The simplest solution to this was to propose matter that doesn't interact through electromagnetism - ie. it doesn't emit or absorb photons, and as such cannot be seen. However, this is very far from untestable, since it would still interact through weak interaction. The problem is that weak interaction is very weak, and finite in range (unlike electromagnetism and gravity, which are both infinite in range). Probable ways to find dark matter would include creating it with particle accelerators or collision detection.

If dark matter is a testable hypothesis then what is the test? "Search for it by smashing atoms together" is not a test. I could say that god is the reason the universe exists, and you just need to find the god particle. Search for it by smashing atoms together. Is that science? No.

I'll also add that weakly interacting massive particles aren't at all weird: neutrinos are extremely common observed particles that interact only through gravitation and weak interaction.

Neutrinos are another hypothetical particle.

It is extremely easy after being exposed to university level physics to transpose experimental evidence for math. However this is not how science works. Everything you put on your whiteboard exists only through induction. Percepts are integrated into concrete concepts by a thinking mind, and then over many many iterations concrete concepts become abstract concepts. This is how math, the laws of physics, logic itself, everything is formed. But it is all still based on empirical evidence. Empirical evidence trumps everything.

So let's consider the evidence. What evidence do you have that gravity bends light at all? Light bends around the sun. Some bits of the universe look like other bits of the universe. This is not very strong evidence.

What evidence do you have that the universe is expanding at several times the speed of light? Fainter stars appear more red shifted. Doppler effect causes a red shift here on earth. It does not necessarily follow that the red shift in stars is caused by the same mechanism. Again, extremely weak physical evidence for a hypothesis as sweeping and difficult to test as the infinitely expanding universe.

Of course, it could be that some day a better theory for gravitation will be discovered that doesn't need dark matter to explain observation. However, it will have to also explain the phenomena that general relativity does (e.g. gravitational time dilation, redshift, gravitational lensing, orbital decay)

Burden of proof is on the claimant in science. The debunker does not need a better theory in order to debunk or throw into doubt an existing theory. We know almost nothing about the universe.

I don't know what to tell you if you think that a theory which has provided working predictions and technology based on it for nearly a hundred years is shit! My point wasn't that if the math works then the theory is correct, as I did provide an example of Nordström's theory which has beautiful mathematics but doesn't at all produce predictions that agree with observations. General relativity does, ergo, it is correct within its realm of applicability.

http://en.wikipedia.org/wiki/Geocentric_model#Ptolemaic_system

You can correctly calculate the positions of the stars with an intricate enough mathematical model even whilst holding the incorrect assumptions that 1/ everything revolves around the earth and 2/ that every celestial body moves in perfect circles only. Of course neither of these assumptions is correct, but the curve can be fit regardless.

It is a fallacy, a nonsequitor, to say that "if the math works then the theory is correct." If the math works, then the curve fits. It has no bearing on the qualitative theory. One can fit a curve to ANY data set with no knowledge of the underlying parameters and variables. One can construct a whole ridiculous story --- ex-post facto --- to explain the curve. Keynesian economics is a good example of this. It means all of nothing. A sound theory is one built from first principles where the first principles are consistent with observation. Relativity does not fit this description.

I was referring to classical information, which doesn't travel any faster than c. Because the state into which the system will collapse is still random, a measurer will not be able to know which state he will measure a particle to be in if the interval between measurers is space-like.

I bolded the part which is exactly as taught to us. Mathematically wave function in quantum physics is a solution to Schrödinger's linear differential equation. It describes the particle completely, and in Copenhagen interpretation superposition is simply when the particle's state is undefined and will exhibit wavelike properties. This wave-like nature of particles is an experimentally verifiable fundamental property of nature.

This is equivocation, which is what I expected. You can't have it both ways. Either the wave function is a complete description of the particle -- in which case it is a physical description of the particle -- or it is not. You want to tell me that the particle has an undefined physical state and yet the physical state is perfectly defined by the wave function. Indeed the very idea that matter can have an 'undefined state' is absurd on its face. If it lacks definition then how can be it be.

I took a look at De Broglie-Bohm interpretation and it seems like it ultimately isn't useful since it also gives only probabilistic results that are exactly the same as Copenhagen interpretation's, but is in addition unnecessarily more complex. Also, it supposedly makes advancing to relativistic quantum field theories (which are in modern particle physics the current best model describing a lot of things) needlessly difficult, but that's another thing.

Basically what I'm saying is if two theories disagree then the one that produces the right predictions is more correct than the other, which should be obvious. In the case that two theories give the same predictions, neither is more "correct" per se but usually one of them is either always simpler or sometimes simpler. For example, there is no reason to use Lagrangian mechanics to calculate how far a puck on ice travels before it stops, since Newtonian mechanics is much simpler in this case. Of course, it is possible to use Lagrangian mechanics to figure it out, but it's much more work for the same results. Any arguing about which of them is more "correct" as a depiction of reality is largely semantics and philosophy, and has no place in physics.

You need philosophy to be a real physicist. If you can't understand why things need to be internally consistent and built from first principles then you will be stuck in the Keynesian-esque curve fitting school of fish.

Copenhagen and Debroglie Bohm are not the same theory. Again you fall into the trap of math = science. It does not. The consequences of a deterministic model of the universe are much more important than you have considered. God does not play dice.

One of the key contradictions in copenhagen is this idea that everything is a probability wave or a wave function. However probability is defined in terms of certainty. Yet at the lowest and most basic level of matter in compenhagen, nothing is certain.

To illustrate what I mean, if I were to explain probability to a 6 year old, I would use a dice. I would say: The dice has 6 sides -- this is a certain fact, and the dice will land on just one of those 6 sides -- this is a certain fact. From these certain facts I can now reason about the various possibilities of throwing the dice with unknown starting parameters. I could get any of the 6 faces pointing up.

In Copenhagen, it is assumed that probability is a valid concept however it is also assumed that nothing is certain. Probability only comes about through deterministic certainty. This is a contradiction. There are many more and this is why you need rational philosophy (particularly epistemology and metaphysics) if you want to actually do something useful with physics. If you can't understand and avoid contradictions you will never be talking about physical reality.

 

[Nick 91]

This is some crazy discussions. +1 to who understand.

 

[Jei jei KK]

Particle accelerators are perfectly valid experiments for discovering hypothetical particles: see Higgs boson, quarks, W and Z bosons for example. Neutrinos stopped being hypothetical in 1956 when they were first detected through their weak interaction with matter. I don't see why you don't consider gravitational lensing effects a proof of gravity bending light, since general relativity predicts our observations to high confidence levels, and you can find hundreds of studies with a simple search. Really, any of the evidence you ask for is available just by searching databases of academic journals' publishings.

Burden of proof is indeed on the claimant, and general relativity makes falsifiable claims that have so far been confirmed with experiments. Gravitational time dilation is found to work as predicted, requiring corrections to GPS systems' clocks as a classical example. Mercurius's (and other planets') orbits slightly differ from what classical mechanics suggested, but lo and behold general relativity predicts them.

There is nothing wrong in assuming that the earth is in rest and all the other stellar objects move, since the physics is assumed to be invariant under transformations - the laws of physics are the same for each reference frame. If this wasn't the case, all of physics would be groundless. It does on the other hand make the mathematics wildly more complex. The second assumption that all the orbits are circular is wrong though, but it's a fairly good approximation with ovals of low eccentricity. I also ran a simulation of the Sun and the four inner planets in Universe Sandbox for fun, and the earth-centered view is remarkably similar to the Ptolemaic model.

I'm still not claiming that simply because the math checks out a theory is correct. It is a requisite, but more important is that its predictions agree with observations.

There is a difference between describing a particle and describing a particle's (quantum) state which isn't just semantics. A quantum state is a vector in Hilbert space which defines a property or a set of properties of the system. To describe a particle means giving it a wave function that correctly states the probabilities to find the particle in a given state. The wave function must be normalized, meaning that the probabilities must add up to 1: it is certain that the particle will be in SOME state when measured. For example, our earlier particle which only had a spin state, and nothing else describing it:

p = 0.4|+> + 0.6|->
The particle is in a superposition, and its state isn't defined. Let's say we do a measurement, and find that it has the state |+>. Now the wave function looks like this:

p = 1|+>
The wave function has collapsed, and all subsequent measurements will tell us that the particle's state is |+>. It is not in a superposition, and the state is defined.

How exactly are Copenhagen and de Broglie-Bohm interpretations not fundamentally the same? From what I understand, they both give the same predictions, and they both can only give probabilities for finding a system to be in a given quantum state. Also, exactly like in Copenhagen interpretation, in de Broglie-Bohm interpretation the wavefunction completely determines how the system behaves.


Also: major thread derailment hooray. I will admit that I haven't had much formal education in general relativity yet: we've yet only focused on special relativity, simpler parts of the mathematics of general relativity (such as Schwarzschild metric and gravitational time dilation), and only conceptually on other areas. In addition I'll state that we're nearing the limits of quantum mechanics, since QM is unrelativistic and is built to describe how given particles behave when given an interaction, while quantum field theories describe what particles are, what interactions they have and what kind of particles exist (even virtual). It also has more correct notions of space, at least in small scales.

 

Particle accelerators are perfectly valid experiments for discovering hypothetical particles: see Higgs boson, quarks, W and Z bosons for example. Neutrinos stopped being hypothetical in 1956 when they were first detected through their weak interaction with matter.

If I'm not mistaken the cumulative evidence for neutrinos consists of a few blips on heavily amplified photo detectors underground. Indeed, the only reason they were even looked for was to make a hypothesis work. (This is called confirmation bias.)

I don't see why you don't consider gravitational lensing effects a proof of gravity bending light, since general relativity predicts our observations to high confidence levels, and you can find hundreds of studies with a simple search. Really, any of the evidence you ask for is available just by searching databases of academic journals' publishings.

This is not really a rebuttal. The idea that gravity can bend light is currently untestable. You cannot isolate the variables for an experiment. For example all large celestial bodies are surrounded by (or composed of) gas. How do you propose to control your variables and ensue that light isn't being bent via traditional / classical optics around the sun? The second 'evidence' for gravitational lensing is literally that some parts of the universe look like mirror images of other parts. But again, with confirmation bias you can look and find a part that naturally looks like a mirror of another part. You can call that evidence but it isn't.

Burden of proof is indeed on the claimant, and general relativity makes falsifiable claims that have so far been confirmed with experiments. Gravitational time dilation is found to work as predicted, requiring corrections to GPS systems' clocks as a classical example. Mercurius's (and other planets') orbits slightly differ from what classical mechanics suggested, but lo and behold general relativity predicts them.

As I said before the math can work yet the qualitative theory can be completely wrong. General and special relativity rest on the postulate that information cannot travel faster than light speed. However this is in contradiction with the empirical observations of quantum mechanics.

If the wave function is a complete description then it is a physical description. If it is a physical description then the universe is explicitly non-local.

Your willingness to throw reason under the bus in order to make your textbooks fit on the shelf next to eachother is called being religious. If you want to be a scientist you need more rigor. Think for yourself and don't accept blindly what the mainstream tells you. At every point in history hitherto the mainstream in physics has been essentially wrong according to the next group of physicists that come along. Try not to forget that.

There is nothing wrong in assuming that the earth is in rest and all the other stellar objects move, since the physics is assumed to be invariant under transformations - the laws of physics are the same for each reference frame.

Good lord. The geo centric model of the universe requires acceleration of every body in the universe except earth. Don't you remember anything from your garbled relativity courses? Acceleration is a real event that changes the way things are.

There is a difference between describing a particle and describing a particle's (quantum) state which isn't just semantics. A quantum state is a vector in Hilbert space which defines a property or a set of properties of the system. To describe a particle means giving it a wave function that correctly states the probabilities to find the particle in a given state. The wave function must be normalized, meaning that the probabilities must add up to 1: it is certain that the particle will be in SOME state when measured. For example, our earlier particle which only had a spin state, and nothing else describing it:

NO.

Again you would have me believe that the wave function is not real but that it is real at the same time.

If the wave function is a complete description of the particle THEN it is a physical description of the particle. It is not an approximation, it is the actual state of the particle.

You want to have it both ways -- you want to say its an approximation and that the particle is in an 'undefined state' until you apply your mod squared. This is bullshit. The particle IS the wave-function -- and it continues to be until you apply your mod squared (i.e. invoke 'observation'.) That is what Copenhagen is really saying. Openly contradicting themselves, they say that that the particle is 'in an undefined state' which is 'explained perfectly by the wave function'. If you can't even see this basic contradiction you have no hope to get anywhere in quantum.

But now I am just repeating myself.

Learn just a little bit of philosophy and you can debunk 90% of the nonsense in quantum. http://en.wikipedia.org/wiki/Socratic_method

If you are interested in the reality behind the math do a Socratic examination. None of the lecturers while I was studying physics could answer the contradictions in Copenhagen. It is not a lack of understanding on your or my part -- if you have read the textbook then you have read the textbook. It is rather that Copenhagen cannot be understood because it is not internally consistent. It hides its contradictions behind the quantum formalism but will never answer you the three basic questions to satisfaction: 1/ What IS the wave function? 2/ What IS observation, why does it cause wave function collapse and why are we the only ones able to do it? 3/ How can everything be a probability when probability itself, in order to be a valid concept, requires deterministic certainty?

The final secret of Copenhagen they don't want you to admit to know is that wave function itself is a non-local hidden variable.

If you consider De Broglie–Bohm: The universe is deterministic AND non-local, the wave function is a real physical field, and humans or 'observers' are not special and 'wave function collapse' is our discovery of the non-local hidden variables. It is a sensible interpretation of the empirical evidence for quantum mechanics. This doesn't mean its right, but in order to get anywhere with a hypothesis you first need one which is internally consistent (which Copenhagen is not.)

But by all means go back to Copenhagen and continue to ignore the contradictions. After all science has become a pay cheque, not a quest for knowledge. People aren't interested in the truth, but rather in how much grant money they can scrape together.

Source: 6 years of university education including 2 of physics.

 

[Jei jei KK]

I had trouble finding this thread because it was stickied :V

Here's a list of some neutrino detection experiments. Testing a hypothesis is not "confirmation bias", it's "scientific method". To explain nuclear reactions the existence of a weakly interacting non-charged particle was proposed, and its supposed interactions were also figured out. Then, just like when testing any other hypothesis, experiments were conducted to see if the predicted phenomena occured. It did, which suggested that the hypothesis was correct. Since the first scintillation experiment there have been many more confirmations of neutrino reactions. There also have been experiments where neutrino collisions have caused nuclear reactions in which chemical elements have changed into other chemical elements.

As I said in my previous post (probably should've written it earlier), I don't have the mathematical tools to do much with general relativity. As such, I can't show you myself the predictions of lensing made by GR and compare them to classical optics' predictions. You *can* approximate the gas density and such around the sun and again, compare the predicted lensing to observation. Or you could work out how the gas should be distributed if the lensing was caused by ordinary refraction and then see if it's reasonable. In the case we find out that optics isn't a reasonable model for the phenomenom, we can figure out that either 1) there was a measurement error, in which case we try again, 2) there's a problem with some assumption or approximation, in which case we try a more complex model for the gas, 3) optics doesn't work as an explanation of the phenomenom. A different model should be used.

The fact that non-relativistic theories (eg. quantum mechanics) contradict relativistic theories isn't exactly news. That's why quantum mechanics was expanded into quantum field theories, which take special relativity into account. General and special relativity deal with classical physical information, while quantum theories deal with quantum information which are different concepts in physics. If mix the concepts then you're extending the theories outside their realm of applicability. Classical mechanics works perfectly fine on regular scales with speeds << c, it is a good approximation of a more-encompassing theories: special and general relativity both reduce to classical mechanics on smaller scales. Quantum mechanics also reduces to classical mechanics on larger scales. Quantum electrodynamics reduces to classical electrodynamics. Classical electrodynamics or mechanics aren't "essentially wrong", they are approximations like everything else in physics.

I'll admit that I didn't think the heliocentrism point through, since you have to add pseudoforces in if you use an accelerating reference frame in classical mechanics.

Copenhagen interpretation is of particle-wave duality, that everything can exhibit qualities commonly associated with particles and waves, but not simultaneously. Calling a thing simply "particle" was misleading. I apologize for being bad at explaining. Wikipedia offers a concise explanation that, to me, seems to answer your first two questions:

Wave&#8211;particle duality is deeply embedded into the foundations of quantum mechanics. In the formalism of the theory, all the information about a particle is encoded in its wave function, a complex-valued function roughly analogous to the amplitude of a wave at each point in space. This function evolves according to a differential equation (generically called the Schrödinger equation). For particles with mass this equation has solutions that follow the form of the wave equation. Propagation of such waves leads to wave-like phenomena such as interference and diffraction. Particles without mass, like photons, has no solutions of the Schrödinger equation so have another wave.

The particle-like behavior is most evident due to phenomena associated with measurement in quantum mechanics. Upon measuring the location of the particle, the particle will be forced into a more localized state as given by the uncertainty principle. When viewed through this formalism, the measurement of the wave function will randomly "collapse", or rather "decohere", to a sharply peaked function at some location. For particles with mass the likelihood of detecting the particle at any particular location is equal to the squared amplitude of the wave function there. The measurement will return a well-defined position, (subject to uncertainty), a property traditionally associated with particles. It is important to note that a measurement is only a particular type of interaction where some data is recorded and the measured quantity is forced into a particular eigenstate. The act of measurement is therefore not fundamentally different from any other interaction.

[continuing to QFT]

For the third, I don't really understand what you mean by probability requiring determinism to be valid. Can you elaborate?



E: Actually it turns out that it's very simple to show that causality isn't violated by quantum entanglement or wave function collapse, using just rudimentary quantum mechanics.

 

I had trouble finding this thread because it was stickied :V

Here's a list of some neutrino detection experiments. Testing a hypothesis is not "confirmation bias", it's "scientific method".

No, it is confirmation bias. See if you can understand the difference between them:

Confirmation bias (also called confirmatory bias or myside bias) is the tendency of people to favor information that confirms their beliefs or hypotheses

Unfortunately most scientists exhibit confirmation bias in not considering the set of all possible hypotheses which might explain the results of an experiment.

Consider the difference between these the following two examples:
1/ A new drug is discovered, a random control group is set up which is given a placebo, and a second random drug group is set up which is given the drug. Both groups are statistically large. After the testing period the control group has a mortality twice that of the drug group. The conclusion drawn is not confirmation bias.

2/ A theory requires that in order to explain the shape of the human hand, a prehistoric man with a hand of seven fingers must have existed. Research groups dig up hundreds of ancient bodies looking for a skeleton and find one with seven fingers. They then conclude that this theory must be correct, for the man with seven fingers was found. This conclusion IS confirmation bias. It is not scientific.

Do you understand the difference?

To explain nuclear reactions the existence of a weakly interacting non-charged particle was proposed, and its supposed interactions were also figured out. Then, just like when testing any other hypothesis, experiments were conducted to see if the predicted phenomena occured. It did, which suggested that the hypothesis was correct. Since the first scintillation experiment there have been many more confirmations of neutrino reactions. There also have been experiments where neutrino collisions have caused nuclear reactions in which chemical elements have changed into other chemical elements.

The problems with the neutrino are 1/ it is a hypothetical particle designed to explain away a problem in a theory and 2/ cannot be directly detected 3/ it is not well defined. The experiments done for it cannot DISPROVE the hypothesis, they can only prove it. Therefore you have inherent confirmation bias at work. When the experiment is modified enough and the hypothesis is modified enough, eventually the criteria for 'proof' will be satisfied, whether or not it actually exists.

http://en.wikipedia.org/wiki/Neutrino#Flavor_oscillations

The neutrino is whatever they want it to be, whenever they want it to be. It 'changes its flavours'. It is a stop-gap to explain where spin goes in beta decay, just as the 'higgs-boson' is a stop gap to explain why massy particles have mass.

I'm not against the neutrino, there's a slim possibility it could actually exist. However a simpler explanation should be sought than an invisible almost massless almost non-interacting magical particle which randomly changes to whatever is useful at the time of detection.

As I said in my previous post (probably should've written it earlier), I don't have the mathematical tools to do much with general relativity. As such, I can't show you myself the predictions of lensing made by GR and compare them to classical optics' predictions. You *can* approximate the gas density and such around the sun and again, compare the predicted lensing to observation. Or you could work out how the gas should be distributed if the lensing was caused by ordinary refraction and then see if it's reasonable. In the case we find out that optics isn't a reasonable model for the phenomenom, we can figure out that either 1) there was a measurement error, in which case we try again, 2) there's a problem with some assumption or approximation, in which case we try a more complex model for the gas, 3) optics doesn't work as an explanation of the phenomenom. A different model should be used.

I'll save you the work. Gravitational lensing just uses snells' law at the end of the day.

I'll point out also that there is evidence standing against gravitational deflection of light which I've never seen anyone bother to answer. See: http://www.newtonphysics.on.ca/eclipse/

But beyond the evidence, let's return to the argument briefly:
1/ Light is a massless particle.
2/ Gravity bends light
3/ But gravity can't bend light because gravity is a function of mass.
4/ Therefore the mass of the star must instead bend 'space itself', so that light takes a 'longer path' and 'appears bent'.

When mass 'bends space', what is the equal and opposite reaction of space on the mass? Or isn't there one.

General Relativity doesn't make sense. It doesn't make sense to give attributes to space -- that is to give attributes to the absence of that which exists. What General Relativity really is then is an aether theory: It says that the aether is affected by the mass, and that the light travels through the aether and takes longer due to the effect.

There are about a thousand other problems with it in logical terms but we can save those for another day. But just to re-iterate this is an insane multiplication of entities. Every point in space must now contain localized aether. Almost any other explanation would require fewer entities.

The fact that non-relativistic theories (eg. quantum mechanics) contradict relativistic theories isn't exactly news. That's why quantum mechanics was expanded into quantum field theories, which take special relativity into account. General and special relativity deal with classical physical information, while quantum theories deal with quantum information which are different concepts in physics. If mix the concepts then you're extending the theories outside their realm of applicability. Classical mechanics works perfectly fine on regular scales with speeds << c, it is a good approximation of a more-encompassing theories: special and general relativity both reduce to classical mechanics on smaller scales. Quantum mechanics also reduces to classical mechanics on larger scales. Quantum electrodynamics reduces to classical electrodynamics. Classical electrodynamics or mechanics aren't "essentially wrong", they are approximations like everything else in physics.

Hanging a lantern on a contradiction doesn't make it less of one. Further, again, redefining concepts by putting the word quantum on the front is just the fallacy of moving the goalposts AND floating abstraction fallacy. Again: Probability is based on certainty. But Copenhagen would have you believe that certainty is based on probability. A complete and total contradiction. And they do this by just calling it quantum probability, or a wave function, or whatever.

Copenhagen interpretation is of particle-wave duality, that everything can exhibit qualities commonly associated with particles and waves, but not simultaneously. Calling a thing simply "particle" was misleading. I apologize for being bad at explaining. Wikipedia offers a concise explanation that, to me, seems to answer your first two questions:

This is begging the question fallacy. What IS the wave function? Your answer was: " a complex-valued function roughly analogous to the amplitude of a wave at each point in space". In otherwords your answer is that a wave function is a function that looks like a wave.

If you can't see why that's not an answer I can't help you. Synonyms aren't definitions. http://en.wikipedia.org/wiki/Begging_the_question

The second question you answered again in bold with: "measurement is only a particular type of interaction where some data is recorded and the measured quantity is forced into a particular eigenstate." Again this is begging the question. What is said here is "measurement is when the wave function collapses." It then goes on to say: "The act of measurement is therefore not fundamentally different from any other interaction." This is just a contradiction. If measurement is not fundamentally different from any other interaction then there is no wave function. Any interaction between anything would collapse the wave function. This doesn't answer at all why wave function collapse can only be invoked by human beings either.

For the third, I don't really understand what you mean by probability requiring determinism to be valid. Can you elaborate?

I already did. If you want to understand then you should read the links I give you. As an exercise why don't you try to explain to me what probability is without assuming that the universe is causal.

E: Actually it turns out that it's very simple to show that causality isn't violated by quantum entanglement or wave function collapse, using just rudimentary quantum mechanics.

Irrelevant. When you attempt the above exercise you will immediately hit a performative contradiction. Philosophy is important and you don't know the first thing about it. How are you supposed to study the physical world when you don't understand 1/ What a thing is, 2/ What makes a thing true, and 3/ What is a valid concept.

 

[Jei jei KK]

I'm going to give up now since we don't even seem to have any sort of agreement on what constitutes an experiment or not.

I'll address that the proof isn't "irrelevant" - it's shown that within the framework of QM, measuring one particle isn't explicitly measuring the other, even if entangled, and therefore there is no signal travelling through space associated with it.

It really seems like you're denying observationally confirmed theories that make valid predictions with semantics based on incomplete understanding and personal feelings about how things should be, and discarding experiments just because, while not proposing theories for replacement. Even if you managed to find a hole in, say, general relativity, do you think the scientific community will go "Oh, there seems to be a small technicality in some part of this theory's applications, drat! I guess we better throw every other part we've been confirming and applying for the past century to the trash instead of trying to fix it"?

 

I'm going to give up now since we don't even seem to have any sort of agreement on what constitutes an experiment or not.

I'll address that the proof isn't "irrelevant" - it's shown that within the framework of QM, measuring one particle isn't explicitly measuring the other, even if entangled, and therefore there is no signal travelling through space associated with it.

The argument that classical information cannot be transferred (by an experimenter) and therefore no information is transferred is a non-sequitur. The other end of the universe must know about the collapse of the wave function instantaneously. This is information transfer.

It really seems like you're denying observationally confirmed theories that make valid predictions with semantics based on incomplete understanding and personal feelings about how things should be, and discarding experiments just because, while not proposing theories for replacement.

I'm not denying any observationally confirmed facts. The results of all experiments are open to interpretation -- this is called being a scientist. That you believe whatever you are told in a textbook or by your teachers is called being a zealot. Further, if you understood logic a bit better you would know that no replacement hypothesis is needed to discredit an existing one. Indeed this would be shifting the burden of proof: http://en.wikipedia.org/wiki/Philosophic_burden_of_proof

Even if you managed to find a hole in, say, general relativity, do you think the scientific community will go "Oh, there seems to be a small technicality in some part of this theory's applications, drat! I guess we better throw every other part we've been confirming and applying for the past century to the trash instead of trying to fix it"?

This is called basing your understanding of the world on faith and the beliefs of others.

It is completely irrelevant to the nature of things -- the physics of the universe -- what other scientists believe and how strongly they believe those things.

All that matters in science is the evidence, the logical consistency of the theories that explain it, and the predictive power of those theories. It seems you are not concerned with any one of these three, but rather only with how many and which people believe in what. This is why you are engaged in religion, not science.

If there's one thing I would have you take away, it would be this: Where you see contradictions in physics, the physics is wrong. Logical consistency is of paramount importance in physics. 'The math makes accurate predictions sometimes' is not a substitute for logical consistency.

I expect you'll do quite well in your degree. The less you question them the better marks you'll get. You might even manage a job in physics ... what few there are to be had.

 

Final quote:

&#8216;The creative period passed away &#8230; The past became sacred, and all that it had produced, good and bad, was reverenced alike. This kind of idolatry invariably springs up in that interval of languor and reaction which succeeds an epoch of production. In the mind-history of every land there is a time when slavish imitation is inculcated as a duty, and novelty regarded as a crime &#8230; The result will easily be guessed. Egypt stood still &#8230; Conventionality was admired, then enforced. The development of the mind was arrested; it was forbidden to do any new thing.&#8217; &#8211; W.W. Reade, The Martyrdom of Man, 1872, c1, War.