My Introduction Question.......concerning Superposition

[PersonalPronoun]

Hope this is the right sub-forum for this..........

 

I read an article the other night that postulated that superposition is indeed the Q.M. Reality.

After I read it, I thought about Schrodinger's cat.

 

It seems that the whole thought experiment is designed to show how a large system can be affected by superposition.

The problem, for me, is this:

In the thought experiment, neither the cat, nor the radioactive atom are in a state of superposition when they enter the box.

The cat is alive, and the atom has not decayed, both are in a definite state.

 

At some point, the atom is assumed to enter a state of superposition, thus bringing the cat into the same state.

The thing is, according to the experiment, we can not know when superposition occurs.

In fact, the only thing we can know, is how the superposition has collapsed once we've opened the box.

So, in the experiment at least, we can never observe superposition.

 

Wasnt that the same thing as saying that superposition was Unfalsifiable?

 

What am I missing (besides a scientific education?)

[pgrmdave]

So, in the experiment at least, we can never observe superposition.

 

Wasnt that the same thing as saying that superposition was Unfalsifiable?

 

What am I missing (besides a scientific education?)

http://en.wikipedia.org/wiki/Quantum_superposition#Experiments_and_applications

[AnssiH]

Hope this is the right sub-forum for this..........

The philosophy section might have been more appropriate but you know, details details...

 

So, in the experiment at least, we can never observe superposition.

 

Wasnt that the same thing as saying that superposition was Unfalsifiable?

Yes it is. Personally I wouldn't call Schrödinger's Cat a "thought experiment" at all though since it doesn't really tell anyone anything about why you'd need to use the concept of superposition at all. It's just a whimsical tale that everyone likes to regurgitate to their friends in a bar.

 

Just think about it a bit. Superposition is by definition something you cannot directly observe. You can't first define what "a state of an object" means, and then turn around and say you are seeing two such states simultaneously. That's just epistemologically - "by definition" - not possible.

 

You can however device a theory that necessitates the use of a concept of superposition, where it occurs by definition any time you are not looking. That is what QM is.

 

The whole EPR and Schrödinger's Cat conundrum arose from the discussions related to whether or not superposition should be viewed simply as representing our lack of knowledge of the state of the system (i.e. only occurring in our head), or representing an effect that happens in reality when we are not looking. Schrödinger's Cat was just one of many ways to point out the absurdity of the latter position, as if it was not obvious already.

 

The reason why the concept is used at all is that it is quite useful concept in quantum mechanics. It is important to recognize that using the concept of superposition does yield different expectations than assuming "continunous existence of definite states to defined objects" (such as photons). Just like it does in double slit experiments.

 

I'd suggest investigating Bell's Theorem and its associated experiments to get a better idea about why QM concepts are trumping classical concepts.

 

But when all is said and done, superposition is still just one possible ontological interpretation we can conjure up to explain why QM is valid.

 

The problem with assuming reality of superposition is of course that it makes reality "actually" reactive to our observations in a semi-idealistic sense; by "gaining knowledge" about the system you "affect the system".

 

If you investigate Bell's Inequality, you see why QM validity necessitates us to state that either "reality" or "locality" is false (see "Bell's Inequality").

 

Note that "reality" here actually refers to assumption that the objects we have defined exist in reality in the way we have defined them. You know, that they are real objects with real identity across "time" and all that.

 

But before we got to this type of representation of reality, all the quantum mechanical and classical particles and objects had to be defined in one's mind. If you are interested, there is a lot of discussion in the philosophy section about purely logical and epistemological reasons why particles are defined in a way that makes them obey quantum mechanical relationships (or see the blog in the signature for full presentation). Meaning, for instance, that our expectations of seeing a photon in such and such circumstance *in the first place* is related to quantum mechanical propagation of our own expectations of finding "a particle" form such and such position.

 

If you follow that whole presentation you can see exactly why our own *representation of reality* is composed of entities that do appear to react to our observations in a way that they don't seem to have a definite state in between observations. But at the same time why there's no reason to believe that the universe itself is actually reacting to your observations. It's just that "objects" have been defined in a way that the probability of "seeing them as we've defined them" at all makes them behave that way.

 

Don't get me wrong; it is entirely possible to create valid theories where the universe does react to your observations. It's just that there's no solid reason to hold onto such belief. As an example, if you follow the links in the wikipedia article that Pgrmdave linked to, you can easily see that they simply choose to interpret an experiment as an indication of superposition. They are obviously not actually observing superposition in any more "direct" sense than an ordinary double-slit experiment is "observing superposition". Besides all the hype they apparently like to place to their own experiments, they are in actual fact only observing one state for one object, at all times. You know they are if you understand why superposition cannot be observed *by definition*.

 

Now, you said you read an article that postulated superposition as something occurring in reality. I'm curious, do you mean they simply stated that such is their belief - thus its real - but did not attempt to defend that idea at all?

 

If you are interested of following a defense of some interesting logical connections in relation to QM, maybe take a look at;

http://foundationsofphysics.blogspot.fi/2014_07_01_archive.html

 

And to view the whole presentation, perhaps start from;

http://foundationsofphysics.blogspot.fi/2014_04_01_archive.html

 

-Anssi

Edited February 21, 2015 by AnssiH

[PersonalPronoun]

The philosophy section might have been more appropriate but you know, details details...

Hey, thanks for taking the time. I am very interested. I have read a little (very little) about Bell's theorem, but now I think I'll read much more.

 

I do adhere to the idea that our observations do effect reality.

I get frustrated with our lack of the use of "AND," because "Either/or," just doesn't seem to fit well all the time.

I dont think we've created all of reality, but I think we do create some of it.

 

Anyway, the article I read about superposition was, I believe, based on some current work by physicists.

I read it in my news magazine. I'll try to find it and post a link to it here for you.

I'd enjoy hearing your input on it.

[AnssiH]

Anyway, the article I read about superposition was, I believe, based on some current work by physicists.

I read it in my news magazine. I'll try to find it and post a link to it here for you.

I'd enjoy hearing your input on it.

Sure, just give me a link and I'm sure I'll have some comments to make...

 

-Anssi

[pgrmdave]

Similar idea: Scientists capture first ever image of light acting as a particle and a wave

[AnssiH]

Similar idea: Scientists capture first ever image of light acting as a particle and a wave

That's an excellent example of generating undeserved hype by stretching some semantics. They have plotted some data into a graph and now they call it "a photograph". Looking at the comments, people seem to think that plotted graph is in fact some kind of a naive-realistic "photograph" of light acting as a wave and photons. Probably because the article calls it that way. "Where's the wire in relation to that photograp?" It's a data graph! I wonder how exactly people think photographs are generated, if not by photons exciting a photographic plate. It's not like you can photograph a photon or an electron in flight. You are merely catching photons (or in this case, electrons) and creating an image based on that recorded data. Of course, photographs are data graphs so, just a small stretch of semantics and you are there (Now I want to see them start calling all kinds of pie graphs also photographs).

 

I also don't see how is this "first ever" such graph. They map electron velocities and/or scattering through a wire that is beamed with photons, and they find that electrons appear to be more affected by photons in ares where they expect to have more photons. There's no link to any paper, but going by what the article says.

 

The point being that it's a wave function that generates expectations as to where the photons are going to be found, and at the same time the electrons are impacted in a way that implies presence of photons.

 

It's not in any stronger sense a visualization of "light as a wave" than ordinary double-slit experiment. Also, there are videos done decades ago that are demonstrating objects behaving as packets and waves at the same time. Such as this;

 

Now I'm inclined to further comment that, as has been discussed on the philosophy sections, there really appears to be a clear algebraic connection between QM wave functions, and plainly epistemological symmetries that arise from general data plotting considerations.

 

The QM wave functions do in fact yield the probability of finding a particle (that we have defined) from such and such position at such and such time. The probability function does interfere with itself, but it still represents exactly the probability of finding A PARTICLE THAT WE DEFINED from some location.

 

Typically at this point people will try and think of an ontological explanation as to why is it that the wave function works. In a naive realistic world where reality is actually made of particles with persistent identity, the wave function obviously should not yield correct answers. When coming up with ontological explanations people are always also hypothesizing what reality is when we are NOT looking. That by itself already means you can always come up with all kinds of ontologies that cannot really be falsified. Many-worlds, transactional, Copenhagen, these are all unfalsifiable ideas at their core. And yet even many scientifically aligned people like to pick their favourites. There is another word for this behaviour, and it's belief. Or religion.

 

Don't get me wrong, quantum behaviour is very interesting and important thing to think about. It's just far too common that people get tangled up into merely arguing about unfalsifiable bullshit. We can't possibly know what occurs between our observations. We just know what kind of mathematical function yields the probabilities for the next observation.

 

In the meantime everyone are missing that there really are purely general epistemological reasons for us to define "objects" in a way that consequent observations of those "objects" do follow the predictions of quantum wave function. This being so, why should we also assume that reality just so happens to be made of "the stuff" exactly like we invented them as part of our theories? By a happy co-incidence? Having an epistemological reason means there's no reason to invent (unfalsifiable) ontological reasons anymore.

 

What we have in most quantum interpretations is what I call a "cart before the horse" situation... Just because we use 10 base number system, there's still no reason to think reality cares about that mode of thinking. Just because we interpret frequencies as colors, there's no reason to think reality in itself looks "colorful". Just because we categorize reality with terminology where there are "particles" that obey quantum mechanical wave function, there's no reason to think reality actually gives a rats *** about our chosen representation and prediction method.

 

I don't know about you, but I do appreciate it when unknowns are considered "unknowns", and not substituted with whatever fantasy beliefs happen to tickle our fancy.

 

-Anssi

[LaurieAG]

Thanks for your detailed explanation AnssiH as I had similar concerns and received no response when I asked the following question on another forum.

 

 

Which direction is the nano wire aligned in with respect to the 'photograph' if you make the y axis perpendicular, the x axis to the right and the z axis to the left?