/sci/ - Science & Math

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Anonymous Sun Apr 3 21:22:45 2011 No.2826676 [Reply] [Original]

Somebody explain the measurement problem to me.

How can an atom be spread out evenly everywhere until it is observed? If that's true, how is it that we can't change the universe consciously through observation? If we can't do that, how do atoms have any sort of integrity? How is there reality?

Explain this please.

>>	Anonymous Sun Apr 3 21:24:45 2011 No.2826683 >citation needed

>>	Anonymous Sun Apr 3 21:26:45 2011 No.2826687 OP doesn't know what observation actually means.

>>	Anonymous Sun Apr 3 21:27:45 2011 No.2826696 File: 37 KB, 400x524, the secretdvd.jpg [View same] [iqdb] [saucenao] [google] >how is it that we can't change the universe consciously through observation? But we can.

Anonymous Sun Apr 3 21:28:45 2011 No.2826699

well i don't like the uncertainty principle either but it's just how things are

>now you realize that everything inside you behaves the same way so you have a probability of conducting the experiment and that there is nothing conscious about you... unless you want to say that everything is conscious which has no implications just like the continuum hypothesis

>>	Anonymous Sun Apr 3 21:29:45 2011 No.2826705 OP, we can't explain it because it is as of yet unsolved. Quantum wave function collapse is fucking mysterious and freaky.

Anonymous Sun Apr 3 21:30:45 2011 No.2826709

>>2826687

And you must be too stupid to explain it since all you did was make a smug statement. Now I know your first reaction will be "fuck you douche" followed by "but that's what you just did!". However since you were the one who initiated this interaction with your dumbass post it means you are in fact the douchebag and I am allowed to make a smug statement to point that out. :)

Anonymous Sun Apr 3 21:31:45 2011 No.2826710

You are caught up in your own predispositions about how matter behaves.

Since we have always seen things falling off of tables and cars moving, we have ingrained in our brains that things behave like particles: they have a specific size and shape, and they can translate, twist, grow, shrink etc.

But actually things do not behave this way - we are just looking from a distant enough vantage point at a large enough collection of items that, statistically, the group looks like a "particle". On subatomic scales, true nature emerges: things behave in ways that appear strange to us. Electrons, for example, have some wave properties and some particle properties.

This is just the way things are - you can't really explain it further. They behave this way, and we only recently have been able to look close enough to see it. It is erronious to ask "how can it be this way?" because that is how Nature behaves, and it is our own fault for trying to make it behave the way we want it to.

Anonymous Sun Apr 3 21:33:45 2011 No.2826725

>>2826709

ok fine let me explain. When he says "observed" he actually means "interacted with" Something doesn't have to be conscious to observe something. For example, when we observe a particle, the wavefunction collapses because we hit it with a photon, not because our mind pervcieved it.

>>	Anonymous Sun Apr 3 21:35:45 2011 No.2826733 No one knows the answers to any of your questions. We only know what we can measure.

Anonymous Sun Apr 3 21:36:45 2011 No.2826743

This is really interesting, but want to hear something cooler?

Atoms have consciousness.

At creation an atom must adopt one of three types of spin. This spin is unaffected by anything but determines what way the atom groups itself. Atoms are assembled into molecules according to these choices, in other words, the universe is here by design not of god, but of particle.

The more you know.

Anonymous Sun Apr 3 21:37:45 2011 No.2826753
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every time i read about quantum experiments i just convince myself that deep down things are just fundamentally different..
there are no balls of matter it's just different and our minds are not used to it
and it's just amazing that a world that we perceive as logical could be build upon such shaky grounds
pic semi related

>>	Anonymous Sun Apr 3 21:39:45 2011 No.2826762 >>2826743 Okay this is just bullshit, right guys?

>>	Anonymous Sun Apr 3 21:40:45 2011 No.2826765 Very interesting thread.

>>	Anonymous Sun Apr 3 21:41:45 2011 No.2826766 >>2826743 Dumbass. >Trying to apply something as complex as "consciousness" to an atom, then acting like atoms have free will...

>>	Anonymous Sun Apr 3 21:41:45 2011 No.2826769 >>2826743 Er...all atoms of the same isotope will have the same total spin. What can change is the projection of the spin state, but there is a favored state due to the exchange interaction.

>>	Anonymous Sun Apr 3 21:42:45 2011 No.2826775 >>2826769 How does the projection change?

>>	Anonymous Sun Apr 3 21:43:45 2011 No.2826781 Since we're talking about loony physics things here, this is something that's always bothered me: Why are black holes represented by discs? Wouldn't they have equal gravity from all angles, being single dense particles and all?

>>	Anonymous Sun Apr 3 21:45:45 2011 No.2826789 >>2826775 Either God, Dumbledore, or consciousness.

>>	Anonymous Sun Apr 3 21:45:45 2011 No.2826794 >>2826775 Interactions with magnetic fields, thermal excitation from the ground state projection are just two examples.

Anonymous Sun Apr 3 21:47:45 2011 No.2826798

>How can an atom be spread out evenly everywhere until it is observed?

It's not spread out evenly everywhere. The places and states it could be in obey a distinct probability function.

>how is it that we can't change the universe consciously through observation

People unfamiliar with QM fixate far too much on a term that only stuck because it is how we discovered this quantum property in the first place.

It is the act of detection or measurement in order to make the observation which collapses the wave function. You cannot observe something without interacting with it in some way, and it is this interaction that realizes the state. No conscious observer is required at all.

>>2826781

Actually it's more toroidal if it's spinning, which all we've detected thus far appear to be.

>>	Anonymous Sun Apr 3 21:49:45 2011 No.2826809 >>2826781 They are disks because it is easier to picture them in 2D (like a hole in the ground). You are correct, they are like points in 3D space. Approaching them is just like falling towards Earth from an aeroplane.

>>	Anonymous Sun Apr 3 21:50:45 2011 No.2826820 >>2826798 So what about matter before measurement? I assume it was actualized by interactions with the rest of the particle world then?

Anonymous Sun Apr 3 21:57:45 2011 No.2826850

Quantum physics isn't a description of reality, only a model for making predictions.

This is a forgiveable mistake to make because most teachers and popularizers are so sloppy with their language. Rather than saying, "we model the particle's position as a probability function until an observation is made" (which is accurate and clear), they say "the particle exists as a 'probability cloud' until an observation is made" (which is sloppy and misleading, and you have to make some very generous assumptions to not call it wrong).

It is all done with math they borrowed from physics, invented to handle situations where you have imperfect information. (for instance, how many rivets on a bridge are sound? in the mathematical model of whether the bridge is going to fall down, the state of each rivet exists as a probability function until someone goes and checks them)

>>	Dr. White !!/zv2MTbpUH9 Sun Apr 3 21:59:30 2011 No.2826855 Did you watch this all the way through?

Anonymous Sun Apr 3 22:00:45 2011 No.2826859

>>2826820

It was. Mind you particles are only actualized at the time of interaction. Between interactions you again have uncertainty.

The frequency of interactions is what makes it so incalculably unlikely for macroscopic objects (like a person whose particles are interacting all the time) to uncertainty phenomena, while the states of subatomic particles and force carriers are ruled by probability and uncertainty.

>>	Anonymous Sun Apr 3 22:01:45 2011 No.2826869 >>2826850 >model for making predictions >description of reality these are the same thing

Anonymous Sun Apr 3 22:07:45 2011 No.2826890

>>2826869
They really aren't, especially when it's only a statistical model.

For any given reality, there are an infinite number of possible predictive models which are as accurate as they claim to be, many of which involve the whims of the elves which do things when nobody's looking.

Anonymous Sun Apr 3 22:15:45 2011 No.2826930

>>2826890

The point is to come up with a physical model that accurately describes reality. It is true we "invent" certain concepts, for example specific heat, with the idea of these concepts being placeholders so we can use our model to predict the outcomes under many circumstances. But actually these concepts survive for generations when we realize they have some physical grounds - in this case, the specific heat is related to the chemical bonds in a molecules.

Nature behave the way it wants to, and it is true that there is a certain level of unpredictability, or statistical predictability. However, mankind does its best to explain reality with crude and simplistic molecules, like a child trying to replicate a Monet painting with 2 crayons. The models we create are not definitions of how the universe behaves, rather they are descriptions of what we think happens, based on our sometimes feeble understanding.

So the "models" we create are "descriptions of reality" as we see them.

>>	Anonymous Sun Apr 3 22:21:45 2011 No.2826968 >>2826930 You're not even trying to understand what I said, or to think clearly about how it applies to the topic at hand.

Anonymous Sun Apr 3 22:26:45 2011 No.2826989

>>2826850
This view is flawed as it implies that quantum mechanics is similar to statistical mechanics: a local hidden variable theory.

A local hidden variable theory presumes that the information we have is imperfect [like in statistical mechanics where we don't necessarily know a lot of detail about the individual particles] gives rise to what appears to be probabilistic behavior. But for quantum mechanics, we have a way to test if this is the case. Through spin interactions, we can see if the Bell inequalities are violated. If they are, quantum mechanics is not a local hidden variable theory and the wave function is a real thing.

We see that the Bell inequalities are violated. So, we have either the Copenhagen interpretation, the many worlds interpretation or a non-local hidden variable theory. In all cases, the wave function is an actual thing, what differs between them is what the wave function means.

So, your description is entirely incorrect.

Anonymous Sun Apr 3 22:28:45 2011 No.2827007
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>>2826781
if you mean the completely black event horizon
it's not a disc it's a sphere but on 2d image looks like a disc

>>2826850
you should read more on quantum mechanics
there is no classical way to represent the things that are happening down there...
i don't like it either i thought i could come with a way to represent it.. but no there is no way you can't compare it to something you've seen or experienced
just read Feynman's set of books on physics
(not that i've read them all but i've covered enough to know that much..)

Anonymous Sun Apr 3 22:35:45 2011 No.2827046

>>2826850
>we model the particle's position as a probability function until an observation is made

No. Your classical interpretation of QM would make quantum tunneling events impossible, and every piece of flash memory on the planet (as one ubiquitous example) stands in testament to the fact that tunneling is indeed possible.

Quantum uncertainty is a very real phenomena and this is a large part of what makes people very uncomfortable with it.

Anonymous Sun Apr 3 22:40:45 2011 No.2827075

>>2827007
It is true there is no classical model to describe what is going on down there. But we try to come up with a description of what is happening.

The Schrodinger equation is nearly the diffusion equation, save the inclusion of "i". This is the model we have come up with - a subatomic particle's wave function is almost like imaginary diffusion. This is our physical description of what is happening, we have a mathematical model to describe this physical situation, and until something realizes "oh it actually looks like this", this is the best we can do.

Anonymous Sun Apr 3 22:44:45 2011 No.2827108

>>2826989
>>2827007
>>2827046
Ugh... typical quantum mystics, confusing "we have experimentally eliminated a few of the more simple and attractive classical models" (the truth) with "we have experimentally eliminated all possible non-dice-rolling models" (something which is not even logically possible).

Anonymous Sun Apr 3 22:50:45 2011 No.2827152

>>2827075

This is funny because the Schrodinger equation actually comes from the wave equation from all the derivations I have seen. You see, Schrodinger was trying to figure out an equation to describe deBrooglie waves for electrons in atomic orbitals.

Anonymous Sun Apr 3 22:53:45 2011 No.2827176

>>2827108
Well, for the theory to be a hidden variable theory, we require the transmission of information at faster than the speed of light. Seeing as relativity is pretty well vetted, these theories have mostly been left by the wayside. Though I have met some people with interest in deBrooglie waveguide and Bohmian mechanics, but these still incorporate the wave function as a thing rather than a result of imperfect knowledge.

>>	Anonymous Sun Apr 3 22:54:45 2011 No.2827180 ITT: mostpeople just recite what they read in wiki only 2 people max actually study QM ITT

>>	Anonymous Sun Apr 3 22:55:45 2011 No.2827188 >>2827152 Why is it funny? Do you think you know what you are talking about? Because the wave equation is second-order in time. Meanwhile, the diffusion and Schrodinger equations are first-order in time.

>>	Anonymous Sun Apr 3 23:04:45 2011 No.2827239 >>2827188 Yes, but that does not change the fact that the derivation starts with the classical wave equation. Here is an example: http://vergil.chemistry.gatech.edu/notes/quantrev/node8.html

Anonymous Sun Apr 3 23:12:45 2011 No.2827279

>>2827239

Yes it looks like you start off with a wave equation, but notice that the end result has nothing to do with waves, time, or anything. The equation they derived is not a wave equation.

Wave equations are hyperbolic partial differential equations. Diffusion equations are parabolic partial differential equations. The ways these two behave are entirely different. Schrodinger's equation is parabolic.

Anonymous Sun Apr 3 23:13:45 2011 No.2827288

>>2827180
You think so? Hm... The more knowledgable ones (e.g. the guy who mentioned the Bell inequality) must have studied it properly, I think :P

Time for a poll! If you've studied quantum mechanics PROPERLY in university, post your program, university, year, and course name(s)! :P

ME: 3rd year Engineering Science (Physics Option), University of Toronto (Canada). Took Quantum Mechanics I (PHY356, if I remember)

>>	Anonymous Sun Apr 3 23:13:45 2011 No.2827290 >>2827279 Mathfag here. This is all legit.

Anonymous Sun Apr 3 23:17:45 2011 No.2827313

>>2827176
>Well, for the theory to be a hidden variable theory, we require the transmission of information at faster than the speed of light. Seeing as relativity is pretty well vetted, these theories have mostly been left by the wayside.
Um... no. To NOT have a hidden variable theory, we require the transmission of information at faster than the speed of light.

The objections to a hidden variable theory are different altogether (and mostly have to do with the simplest set of hidden variables appearing to come up different after repeated measurements).

Transmission of information at faster than the speed of light (a.k.a. "spooky action at a distance") is accepted in the mainstream interpretation: when one of an entangled particle pair is observed, and its wavefunction collapses to a single reality through much on-the-spot dice rolling, the outcomes of those dice rolls are instantly transmitted across any distance of spacetime to its partner, so it can obey conservation of angular momentum or somesuch, regardless of the fact that according to the also-mainstream-accepted principle of relative simulaneity, it would make equal logical sense to say that either one of the pair was observed before the other.

Swallowing camels and straining at gnats, my friend. Get used to it.

>>	Anonymous Sun Apr 3 23:17:45 2011 No.2827314 >>2827279 I said nothing about how it ended, only how it was derived. I agree that it looks like the diffusion equation, but it is still derived from the wave equation.

>>	Anonymous Sun Apr 3 23:19:45 2011 No.2827325 >>2827288 Relativity and Quanta (PHYS 200) Introduction to Quantum Mechanics (PHYS 304) UBCfag PS. there's another "Introduction to Quantum Mechanics" that is a 400 level course.

Anonymous Sun Apr 3 23:21:45 2011 No.2827337

>>2827313
>according to the also-mainstream-accepted principle of relative simulaneity, it would make equal logical sense to say that either one of the pair was observed before the other.
oops

>according to the also-mainstream-accepted principle of relative simulaneity, it would ^SOMETIMES^ make equal logical sense to say that either one of the pair was observed before the other.
fixed

Anonymous Sun Apr 3 23:21:45 2011 No.2827336

>>2827314

Read the bottom:
>It is important to point out that this analogy with the classical wave equation only goes so far. We cannot, for instance, derive the time-dependent Schrödinger equation in an analogous fashion (for instance, that equation involves the partial first derivative with respect to time instead of the partial second derivative).

Anonymous Sun Apr 3 23:25:45 2011 No.2827352

>>2827288
>>2827279
I was under the impression that you could only classify PDEs as parabolic, hyperbolic, and elliptic if they were real PDEs. The definition is of the form:
<div class="math"> d = A^2 - 4 B C </div> , and d<0 for elliptic, etc.
However, the coefficients in the schrodinger equation are imaginary, so surely the definition does not hold.

Also, we see wavelike behaviour with the Schrodinger equation. An infinite plane wave is a solution of the Schrodinger equation, which is characteristic of a wave equation. If we have an infinite plane wave and apply the diffusion equation, the waves will quickly disappear. In addition, we can describe any quantum state in free space as the superposition of plane waves...

Finally, the Schrodinger equation is extremely general; if we do not look at the particle-in-free-space case, the Hamiltonian may not look contain anything like a second-order space partial derivative (e.g. consider the spin states of a particle...)

I rest my case :)

Anonymous Sun Apr 3 23:27:45 2011 No.2827360

I don't know exactly how it works but it kinda.... well...eh.. you see... There's this stuff and it kinda does stuff magically... and thats just how the elves and faeries want it to be...

In a few decades someone's gonna figure that junk out, and all of you will have bought the emperor's new clothes because you're dying to have faith in something that's not religion.

>trollface.jpg

>>	Anonymous Sun Apr 3 23:29:45 2011 No.2827367 >>2827360 You realize that all physicists would like to know how / why QM works, right? :P You're not exactly trolling...

>>	Anonymous Sun Apr 3 23:30:45 2011 No.2827371 >>2827352 I meant to say complex coefficients, not imaginary coefficents. Also, you can't define ">" or "<" when you're talking about complex numbers :P

>>	Anonymous Sun Apr 3 23:32:45 2011 No.2827382 >>2827313 >Um... no. To NOT have a hidden variable theory, we require the transmission of information at faster than the speed of light. What? A non-local hidden variable theory will require ftl too. >>2827336 Purdue University PHYS 660 and 661.

>>	Anonymous Sun Apr 3 23:35:45 2011 No.2827390 >>2827352 No, it is parabolic. Parabolic equations are dissipative, hyperbolic equations are conservative. Solutions of the Schrodinger equation dissipate to boundary conditions, they do not propagate back and forth.

>>	Anonymous Sun Apr 3 23:36:45 2011 No.2827395 Wow, a lot of physics undergrads here lol.

Anonymous Sun Apr 3 23:36:45 2011 No.2827391

>>2827352

I'm not the guy you were originally talking to, but my two cents: first off, the classification isn't a "hard classification" outside of 2 dimensions. What it's really looking at is the sign of the eigenvalues of the matrix you obtain using the second order coefficients. Since complex eigenvalues don't have a sign, this obvious doesn't work. However, I would not be surprised if there were still a method of salvaging the classification in certain circumstances. At any rate, the fact that you have a double partial wrt time in one equation and none in the other is a sign that something is very different about these equations.

Anonymous Sun Apr 3 23:38:45 2011 No.2827401

god you guys are fucking dumb

its not actually spread out

we just dont know where it is until/unless we measure it

and the way we measure it (sending streams of electrons) can change its properties

also

>quantum mechanics is only non deterministic with regards to measurement.,

>>	Anonymous Sun Apr 3 23:39:45 2011 No.2827405 >>2827390 Take a linear combination of any two bound energy eigenstates with different energies. You now have a solution to the Schrodinger equation that oscillates back and forth.

Anonymous Sun Apr 3 23:41:45 2011 No.2827413

>>2827390
Uh.... what are you smoking man? Diffusion equations cannot support the propagation of waves (which we clearly have with quantum mechanics). You're forgetting the phase of the wavefunction, man. Heck, consider light. Photons are described by the Schrodinger equation as well, but we also describe the propagation of light EXTREMELY well with Maxwell's wave equations...

The basic point is that the Schrodinger equation, in some special cases (e.g. particle in free space), is essentially a wave equation. In other cases, the Schrodinger equation is not a wave equation (e.g. spins of particles in a magnetic field, etc).
/thread

>>	Anonymous Sun Apr 3 23:42:45 2011 No.2827419 >>2827405 The equation in the provided link can't oscillate, because it has no dependence on time...

>>	Anonymous Sun Apr 3 23:43:45 2011 No.2827424 >>2827401 ... You realize you're speaking with a number of upper-year physics undergrads who have taken a LOT more quantum mechanics courses than you lol?

Anonymous Sun Apr 3 23:46:45 2011 No.2827431

>>2827405
>>2827413

You people are fucking retarded. The time independent Schrödinger equation cannot talk about oscillation or probagation, because those concepts require time. All the derivation in the provided link showed was that if you make a bunch of stupid assumptions about the structure of your solutions to the wave equation, then the spatial variable satisfies another PDE given some physical constraints.

>>	Anonymous Sun Apr 3 23:46:45 2011 No.2827432 >>2827336 Ok, didn't read that one carefully enough. Here is one that goes through how Schrodinger derived the equation. http://www.mpipks-dresden.mpg.de/~rost/briggs4a.pdf

Anonymous Sun Apr 3 23:49:45 2011 No.2827441

>>2827382
>>Um... no. To NOT have a hidden variable theory, we require the transmission of information at faster than the speed of light.
>What? A non-local hidden variable theory will require ftl too.
It's cute and all that you found something to "correct", but there is no contradiction between what you said and what you're replying to.

It says, "To NOT have a hidden variable theory, we require the transmission of information at faster than the speed of light." and not, "No hidden variable theory requires the transmission of information at faster than the speed of light."

To explain the observations of entangled particles without faster than light spookiness, you need hidden variables.

I don't want to get into an argument now about objections to local hidden variable theories. They don't bear on the point I just made.

>>	Anonymous Sun Apr 3 23:50:45 2011 No.2827444 >>2827431 LOL, I was talking about the time-DEPENDENT schrodinger equation....

>>	Anonymous Sun Apr 3 23:51:45 2011 No.2827451 >>2827444 Just admit that you don't know the first thing about probagation.

Anonymous Sun Apr 3 23:56:45 2011 No.2827459

>>2827444
Now you're just being obnoxious. I just took Quantum Mechanics 1 (PHY357) and Partial Differential Equations (APM384) last semester. The PDE course extensively discussed wave propagation and diffusion equations.

Seriously, are you just spouting complete nonsense about a subject you know barely nothing about except from pop-science textbooks and 1st year uni classes?

Anonymous Sun Apr 3 23:58:45 2011 No.2827466

ANYWAY

This whole argument has made my point.

We hold an idea of what is going on at a subatomic level, be it diffusion or wave-like. This serves as a MODEL.

We then come up with equations to describe this MODEL - in this case, the Schrodinger Equation. So we have settled on a description of a physical situation.

In the end, we have made a description of reality AS BEST WE SEE IT, and use this description to try to make predictions. If our predictions fail, it is because our MODEL of PHYSICAL REALITY is somehow flawed, and we must reconsider it.

>>2826850
The point made here is somewhat accurate, in the sense that we don't know exactly what is going on. But we use our imaginations to guess what is going on, and we always base it in physical grounds, going back to fundamental ideas such as ENERGY, MASS, POSITION, CHARGE, etc etc etc.

>>	Anonymous Sun Apr 3 23:59:45 2011 No.2827467 >>2827459 Then can you please comment on how the time-dependent Schrodinger equation should be classified?

Anonymous Mon Apr 4 00:04:45 2011 No.2827482

>>2827467
The time-dependent schrodinger equation is a 1st order PDE with respect to time; the other side of the equation, the Hamiltonian, is completely dependent on the particular situation you are trying to model (e.g. spins, particle in free space, etc.)

You cannot define the equation as hyperbolic, elliptic, or parabolic b/c the definition is only valid if we have real functions, and real coefficients (since the definition includes < and >, which is not defined for complex numbers). However, for the TDSE, both the functions and coefficients are complex...

>>	Anonymous Mon Apr 4 00:08:45 2011 No.2827497 >>2827482 Can the definitions of parabolic/hyperbolic/etc. be extended to PDEs in more than one variable? Because if so, you could classify the TDSE by rewriting it as two PDEs for its real and imaginary parts.

>>	Anonymous Mon Apr 4 00:09:45 2011 No.2827504 >>2827497 The two PDEs would be linked, so no...

>>	Anonymous Mon Apr 4 00:10:45 2011 No.2827508 File: 254 KB, 1500x1087, winning.jpg [View same] [iqdb] [saucenao] [google] >>2827466

Anonymous Mon Apr 4 00:12:45 2011 No.2827513

>>2827466
Well, if your entire argument is that the mathematics of QM properly predict what happens, and we don't understand what is going on / whether the wavefunction is real / how it actually works, then yes....

But that's not much of an argument lol.

Anonymous Mon Apr 4 00:19:45 2011 No.2827539

>>2827513

Yes this is my argument. And if you are worried about why the "wavefunction is real" then you are missing the point entirely, and probably wasting a lot of your time.

As it sits right now, mankind has done a remarkable job describing the universe around it. But when it comes to trying to figure out WHY things are the way they are, that is something we might never be able to figure out. You can waste your time trying to figure out WHY the best way to describe an electron is with a wavefunction, or WHY the gravitational constant is what it is, or WHY we have four fundamental forces, or WHY objects have inertia...but I'm afraid you won't get far, and it is not really worth arguing about on the internet when there is no known answer, and there is a high probability that humans will NEVER know the answer.

>>	Anonymous Mon Apr 4 00:21:45 2011 No.2827550 >>2827539 Looking for a reason assumes there's a reason to be found...

Anonymous Mon Apr 4 00:24:45 2011 No.2827569

>>2827539
>if you are worried about why the "wavefunction is real" then you are missing the point entirely, and probably wasting a lot of your time.
Just like those people who missed the point entirely and were probably wasting a lot of their time worried about why the "atoms really exist".

Or the people who thought, "Well sure, rocks fall down and fuels burns away, so experiment agrees with model as well as the model claims to predict, but is it REALLY because everything's made of the Four Elements?"

>>	Anonymous Mon Apr 4 00:30:45 2011 No.2827595 >>2827569 Why do atoms exist, then?

>>	Anonymous Mon Apr 4 00:30:45 2011 No.2827597 >>2827569 lol good argument but a waste of time the other guy obviously doesn't see things clearly

>>	Anonymous Mon Apr 4 00:38:45 2011 No.2827646 File: 428 KB, 1500x1087, charlier sheenie - whinning.jpg [View same] [iqdb] [saucenao] [google] >>2827508 more like...

Anonymous Mon Apr 4 00:38:45 2011 No.2827647

My favorite interpretation of quantum mechanics is the idea that there's both an initial state |i> of the universe, and a final state <f| which is selected from some set of possible final states randomly following the usual Born rule. You have two wavefunctions, one propagating forwards in time from the past, and one propagating backwards in time from the future.

We then postulate that the value of any observable O is given by its weak value <f|O|i>/<f|i>. In fact experimentally it's possible to measure (for an ensemble -- in any individual weak measurement there is lots of noise) both the real and imaginary parts of these weak values without significantly disturbing the system.

You don't need collapse because the quantity <f|O|i>/<f|i> only contains contributions from the places where the two wavefunctions overlap. If the wavefunction from the past develops two or more branches that are different in a large number of variables (as happens when a measurement is performed), only one of the branches will overlap the wavefunction from the future. The rest of the branches can be ignored, as if the wavefunction had collapsed.

Anonymous Mon Apr 4 00:42:45 2011 No.2827668

>>2827569
>Or the people who thought, "Well sure, rocks fall down and fuels burns away, so experiment agrees with model as well as the model claims to predict, but is it REALLY because everything's made of the Four Elements?"

See
>"If our predictions fail, it is because our MODEL of PHYSICAL REALITY is somehow flawed, and we must reconsider it."

>>	Anonymous Mon Apr 4 01:56:45 2011 No.2828112 bamp

>>	Anonymous Mon Apr 4 03:27:45 2011 No.2828507 Is it possible to teach yourself quantum mechanics?

>>	Anonymous Mon Apr 4 05:44:45 2011 No.2828937 I'm waiting for /sci/ to figure out QM as a whole ITT

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