Quantum Weirdness: WTF

[Cetaphobia]

I am not a science person, no matter how much I fancy myself to appreciate science. It's because of its entanglement with math, because I honestly find science itself to be beautiful.

But this shit makes me frown SO HARD.
http://www.youtube.com/watch?v=DfPeprQ7oGc
http://www.youtube.com/watch?v=ja0UUKbVlhA&feature=related

I get the double slit experiment and I get that it's sort of like Schrodinger's cat, but my mind does not understand.

Is all Quantum stuff batshit like this? You'll have to excuse me asking this before Googling, I have to go to bed and have nightmares about particles knowing I'm watching them alsjdhflaskjf

ITT give me nightmares about quantum weirdness.

(I hope I'm right in putting this here instead of AT)

[Requia ☣]

Is all Quantum stuff batshit like this?

Yes

That second video is half nonsense by the way.

[LMNO]

I didn't feel like sitting through those videos, but I do have a riff on the Double Slit experiment.


Q: The conclusion of the Double Slit experiment (as far as I can tell) reached is that, depending on how you look at the experiment, you will get different results; hence, the observer is creating the results depending on their freely made choices.  This doesn't smell right to me.  What gives?


A:  Yes, it is true that the results of the measurement depend on your free choice of what to measure.  And yes, you can set things up to give results that no reasonable picture of physical reality can explain.  Quantum mechanics not only does not give a reasonable picture of reality, it does not give a picture of reality at all!  It gives results that are totally unvisualizable and unimaginable, but it works. 

The conclusion in your sentence: "The conclusion (as far as I can tell) reached is that, depending on how you look at the experiment, you will get different results; hence, the observer is creating the results depending on their freely made choices." is almost correct, but it's not as solipsistic as you might think. 

The observer ALWAYS decides what to measure.  ANYTHING you measure depends on the setup -- there's a very broad principle of relativity at work here.  You always have to have a coordinate system, a framework, or measurement doesn't make any sense. 

What's interesting about quantum mechanics is that the choices of frameworks include much more than just coordinate systems -- they include whether you're going to measure position, or momentum, for example.  In QM, choosing one or the other is exactly like choosing one coordinate reference frame or another.  Nature will look different from these different perspectives.

In the "double slit" experiment, you make a choice about how you'll look at the boxes.  Two completely different procedures are described.  Choosing one of them amounts to choosing a coordinate frame in which to view the system. 

But nature still gets to decide what you see -- you don't actually create the natural phenomena, you only create the framework for it.  Nature's choice shows up in the part of the experiment where you decide to look inside the boxes.  You will never find a particle in both boxes.  You'll find it in one or the other.  Nature gets to decide which one.  You can't affect that.  All you do is put the boxes there and decide what to do with them. 

So the part of your conclusion that's just a little bit wrong is the statement that "the observer is creating the results..."  You create the conditions for the results, but not everything is under your control.  The two kinds of experiments, by the way, differ exactly in the things that the uncertainty principle says you can't measure at the same time.  The interference experiment measures a wave property (momentum), the experiment where you look in the boxes measures position (where the entity is).

Nature does not obey intuitive rules.  Microscopic nature does not operate in a way that lends itself to visualization.  It's weird.  But there's no rebuttal of the uncertainty principle here.   All this is completely consistent with the uncertainty principle.

[Kai]

After reading that, I think I understand the particle:observer problem better than I ever have.

To make sure I understand correctly, quantum particles behave in manners which are outside the realm of our human experience, so thinking about them in a way that makes sense to our macro based minds will all be metaphor (ie schrodinger's cat in the box experiment), and you don't want to confuse the map for the territory in that case. Observation of different aspects of quanta alters the way they behave, not in the sense of human consciousness has some psychic effect on the particles but rather that measurement alters the behavior by the dynamics of the measurement process. In example, you can choose to measure the speed of a particle but in the act of measuring you alter its direction. I'm guessing that particle/particle interactions will always alter some aspect of velocity, and you can determine which aspect to measure but the other will be altered in the process, thus keeping you from measuring both in the same instant.

Is this close or way off?

[LMNO]

Close.

The first part is spot on.  Quantum Mechanics is not intuitive.  What "feels" right has nothing to do with QM.  our everyday experiences are meaningless when trying to understand QM, so any method trying to explain it in macro terms is invariably paradoxical and weird.

As for the second part, let me use a metaphor.  

There is a rope which is made up of various threads, and you want to observe it.  For some reason* you can't look at it without using a colored filter.  You have a choice between a red filter and a blue filter.

When you look at the rope with a red filter, you see dark blue strands, partially obscured by what appears to be something you can't identify or see.  Odd.  So you switch filters, and you now see completely different red strands, also obscured by something you can't make out.

So, you can conclude two things:

1) The act of choosing red or blue filters changes the fundamental structure of the rope.

2) The rope is made up of both red and blue strands, but you can't see them both at the same time.  Your choice of filter determines which threads you will see.


The answer, according to QM, is #2.  Choosing what you are going to measure (i.e. which color filter you use) determines what you are going to see (i.e. red or blue strands).

Another way to say it is:

Red or blue filter = Particle measurement or wave measurement.

Particle result or wave result = red or blue thread.

Quantum event = entire rope made up of red and blue threads.












*Because all these metaphors are flawed, of course.

[Kai]

Thanks, I think I get it now. What other quantum phenomena besides particle/wave could be considered with this metaphor?

[LMNO]

Pretty much every, "HOLY SHIT! OBSEVER AFFECTS EXPERIMENT!" situation.

In short, it's understood in the macro world that the experiments need to be narrowed as much as possible so there are no unexplained variables, and it only explains one frame of reference.  "This experiment looks at tadpoles in the spring in water of PH 5.6 with overcast skies and half the normal predators with 200PPM arsenic."

QM simply takes this farther than the macro world generally allows.

[Bebek Sincap Ratatosk]

Correct Motorcycle for much of QP/QM... there is still weirdness and WTF, but that's generally in areas like Quantum Entanglement.

Entanglement is just fucking weird.

[LMNO]

Yeah, but only if you try to explain them.

[Telarus]

http://quantumtantra.com/

http://southerncrossreview.org/16/herbert.essay.htm

http://quantumtantra.blogspot.com/




Dude's still alive, might as well network with him. Who wants to come up with a Knighthood?

[PeregrineBF]

Interpreting quantum mechanics is hard. There's no true agreement on which of the many interpretations is correct.
Is the wavefunction real? If so, why can't things travel faster than light? Is the universe deterministic? Is there a unique history, or multiple pasts/futures/presents? Does the wavefunction collapse? Do observers actually affect the system, or just observe it (like the lense analogy)? Or should we just shut up and calculate (instrumentalist view).

[LMNO]

Interpreting quantum mechanics is hard. There's no true agreement on which of the many interpretations is correct.
Is the wavefunction real? If so, why can't things travel faster than light? Is the universe deterministic? Is there a unique history, or multiple pasts/futures/presents? Does the wavefunction collapse? Do observers actually affect the system, or just observe it (like the lense analogy)? Or should we just shut up and calculate (instrumentalist view).

I'm of the opinion that QM doesn't actually try to answer any of these questions.  In a way, asking those questions is just another way of using metaphors and fucking up the explanation.  Discovering the Higgs Boson won't tell us if there are infinite universes, but it will tell us that the standard model is still the best interpretation we have.  So, I suppose I'm an instrumentalist.