# Wave-Particle Duality

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Sorry to drag this back up and give people headaches!

I think I've heard (correct me if i'm wrong) that an electron, given the choice of multiple paths, will somehow take all of them. How?

Its Feynmans Multiple Paths theory.

Basically if you do the maths and say "lets suppose it can take every possible path between A & B" you find that due to quantum interference most of them cancel out an amount to nothing, and the directish (to some fine tolerance) ones are the only ones left over. Put a double slit in the way, and you distort this and find there are a couple of ways it can go, and interfere with itself...

well thats the 10 second version anyway!

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I wonder if the problem here is more related to the terminology than anything else.  For example, photons or electrons say, are described as "particles".  But what is "a particle"?  In the macro world

No, the problem is still alive and kicking Suppose we dispose of the noumenal realm entirely and someone gives us a description of a something, a tree, electron, wave-particle, for example. All well

I think the idea (wunderz?) of wave particle duality can be overplayed? Usefulness depends on lifetime, range, energy (virtual mass etc.) of such things? A convenient model, under specific circumstanc

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I think I've heard (correct me if i'm wrong) that an electron, given the choice of multiple paths, will somehow take all of them. How?

No-one knows, but what you describe is certainly what appears to happen.

Feynman's explanation of the double-slit experiment is great.

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Sorry to drag this back up and give people headaches!

I think I've heard (correct me if i'm wrong) that an electron, given the choice of multiple paths, will somehow take all of them. How?

May be easier to stop thinking of the electron as a particle, consider it more of a cloud.

Then it is a bit easier to see that some parts of the cloud can go down one path and other bits down another.

It is another approximation to whatever is going on, just might help.

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Cloud is better than particle. .......a probability cloud...there is a bizarre thing.

Even the old idea of an electron as a particle orbiting an atom is wrong.. it is more of a 'cloud' around the atom.

I have resigned myself to the fact that they are beyond understanding in terms of human experience. All we can do is try and describe their behaviour in whatever bizarre terms we need to use.

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Does the word 'noumenon' ever get used in this context, or has it been well and truly philosophically trashed?

No, the problem is still alive and kicking

Suppose we dispose of the noumenal realm entirely and someone gives us a description of a something, a tree, electron, wave-particle, for example. All well and good. At the same time we could also suppose an alien culture or being with a differently constituted mind, culture and perhaps with different sensing apparatus and tools, studied the same something and could came up with different conclusions about its nature.

As a mind experiment, this could happen and it does happen in nature. Different animals will experience the something differently according to the nature of their sensory apparatus and the constitution of their brains.

Presumably, no animal except man even has a concept of “tree” along with all the divisions, separations and classifications that this implies (leaf, stem, electron, etc.) So, in a very real sense when we are talking about a tree, or an electron, or a wave-particle, we are talking about concepts, generated by our minds. Seeing as our mind concepts are not the actual something itself being observed (the tree, electron, wave-particle), then from a given perspective there is an epistemological gap - we are describing a something which is not the something

Kant’s noumenal realm was an effort to fix this problem. It was the effort to answer the question: what is the tree, electron, wave-particle we experience independent of the given observation or classification schemes of any observer, culture, human or otherwise? That is, what is this thing objectively, for surely, objectivity is something all science claims to pertain?

And he said, we can’t know. We can’t know anything outside the phenomenal realm. But surely, there must be a thing-in-itself – a tree, an electron, a wave-particle in itself– for if not, then the condition we are in is not one of direct or naïve realism, but rather one much more closely allied with idealism. To cut away the noumenon is to leave us with nothing but phenomenon, which is completely subjective. Hence, reality would be, in some important sense, observer dependent.

But is reality observer dependent? In the Western tradition, a firm line has been drawn between the objective world “out there,” independent of our observation of it. The subjective world is our perspective on the objective world. Of course, this is a metaphysical presumption, not a given fact about the world, so around we go.

Is what we call reality – the universe – a retroactive construction of human observation or is there really a something 'out-there'? And if there is how can we gain knowledge of it independent of our observations of it?

As a side note, it is interesting to ponder that after the 20th century and the studies in quantum mechanics, for example, there may be no reason whatsoever to maintain the fictional divide between the subjective/objective.

The noumenon continues....

Edited by Qualia
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We can only ever imagine anything (and everything) from our own internal perspective, we have no ability to see it any other way, which may or may not be fortunate. We really do not know what we are dealing with here.

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All our descriptions of the quatum world are metaphorical. Metaphors are powerful things but they are not the thing itself...

Or are they?

Oh no!

lly

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As a side note, it is interesting to ponder that after the 20th century and the studies in quantum mechanics, for example, there may be no reason whatsoever to maintain the fictional divide between the subjective/objective.

The noumenon continues....

Interesting, how do we as humans remove ourselves from our own perception of what the universe is.

Well one good way is to use tools, that can measure beyond our own perceptions. i.e radiowaves, infrared, or a HA filter on your CCD

But, as you say the strange thing that our tools have uncovered in the 20th century through Quantum theory, is that everything we observe is all just a projection.

All particles seem to exist in our observable universe, as well as in other dimensions that we cannot sense, using current tools.

So what we perceive is still only in the realms of what we can measure, but their is a whole bunch of universe wrapped up in the space in which  we exist that we cannot perceive or measure.

Lol, makes my mind feel like its bending out of this dimension and into the next.

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We make the tools, we interpret the findings of the tools. Is that objective?

Olly

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If you think the results of the double-slit experiment are weird, consider the triple-slit experiment ...

http://physics.aps.org/articles/v7/96

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We make the tools, we interpret the findings of the tools. Is that objective?

Olly

With certain things I would say yes. For instance we know that E=MC2 is a good approximation of matter as the amount of energy released can be measured and it matches.

So using these type of approximations we can deduce things about the sun to great degrees of accuracy.

But once we go deeper into the quantum world, then I would say No, because the accuracy and methods used to measure, don't give us enough to be able to prove things with great degrees of accuracy.

Put another way, maths is a universal language, 1 + 1 will always equal 2, but in the quantum world this is not true, because everything is based on probability.

So is this just a problem in the way that we understand the quantum world  or is maths fundamentally a flawed human construct?

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What's the probability of us ever understanding Quantum physics?!

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Interesting, how do we as humans remove ourselves from our own perception of what the universe is.

Well one good way is to use tools, that can measure beyond our own perceptions. i.e radiowaves, infrared, or a HA filter on your CCD

Put another way, maths is a universal language

You will appreciate that to go about understanding, making sense of, explaining, considering, and describing those representations of the 'tools', requires that the subject draws upon a reservoir of rule-bound concepts. The subject is thus fettered to theory ladenness.

In this manner, the question is usually set as: what is the reality behind human's rule-bound concepts and rule-following considerations? It is in this respect that the intellectual battle ground is often described as a triadic system of conflict, orbiting about:

Platonism (realism) = the rules are real and have an absolute objective reality. They are universal. They are Ideal. They are perfect and god-like. We grasp them by some transcendental, mystical actuation.

Kantianism (conceptualism) = the rules are real, but are the fabrication of the all too human mind responding to respresentations. Contrary to the mystical Platonists, mathematical thought is a natural outgrowth of the human cognitive apparatus which finds itself in our physical universe, bounded by our own physiology and physical environment. The abstract concept of number, for example, more than likely sprang from the experiences of cave dweller Ug, counting discrete objects probably on his finger tips. In this sense, mathematics is not universal. Humans construct, but do not discover, mathematics by revelation. We can now understand that if so desired the physical universe can thus be seen as the ultimate foundation of mathematics, for after all, it guided the physical brain by evolution, which in turn helped determine which questions this brain would find worthy of investigation. However, the human mind has no special claim on universal, ultimate reality built out of human-math.

Nominalism = there are no rules, just human beings with the desire to apply given concepts, words to their representations. That people use them today is fine stuff, only one must always be aware that these rules are contingent and never absolute.

Superficialy, Platonists are suspicious that the other two ideas open the doors to idealism, that in the ultimate analysis it is simply the human mind that constructs its reality and meaning.

For the Platonist and Kantianists, Nominalism is madness, for if ideas represented by words have no real existence, then the correctness of meaning can be denied. This assertion is a form of eliminativism dressed up in the robes of post-modernism - that people's understanding of representation (reality) is false and that what humans believe as existing probably doesn't exist.

For the Nominalist, the world of universals and Platonism is absurd and the Kantianists are wishy-washy wimps who claim that the mind simply creates the rules but that these rules are universal (pertaining to all humans) mental structures.

I know I haven't got these positions absolutely right, but they're offered with the good faith of potentially framing the debate.

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You will appreciate that to go about understanding, making sense of, explaining, considering, and describing those representations of the 'tools', requires that the subject draws upon a reservoir of rule-bound concepts. The subject is thus fettered to theory ladenness.

I know I haven't got these positions absolutely right, but they're offered with the good faith of potentially framing the debate.

I think you have done a good job of explaining the three positions.

I am probably a bit of a Platonist at heart as I believe that their must be some underlying construct to everything.

I understand Platonism and Nominalism, but I had to do a double take on Kantianism, as it is a first for me.

At first I thought it is the mid point between the two, but did a quick wiki and now understand it to be only rational / logical constructs that hold true under all circumstances can be held as universal. So under this assumption, it is closer to Nominalism when applied to scientific thought, especially in Quantum physics.

As we all know, all the rules break down once inside a black hole, so none of them are really universal

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• 3 weeks later...

For those who struggle with the concept of particle wave duality and the double slit experiment, there always has to be human interaction on the Electrons and Photons that we see and there is a reason for it - as follows:-

The Universe is filled with Photons travelling as waves, those Photons make up the various shapes and objects we see. Now, have you ever wondered why none of them ever get mixed up and the whole soup of sub atomic particles isn't just a sea of chaos, so that Photons coming from one object get entangled with Photons coming from elsewhere? Have you ever wondered how Photons can pass across the front of the Moon and not become engulfed and lost in Photons from the Moon?

Photons always seem to know what they are part of when you look at them and that is because they know you are looking. You cannot collapse the wave function into particles until you look at the target. Take the Moon for example: The light coming from the Moon travels through space as a wave of potential waiting for a receiver or a victim so to speak, when a receiver is present (our eyes) then the wave of potential collapses into particles and is absorbed by our eyes imparting all the information into our brain about the object we are looking at. Now, if it didn't happen that way and the wave of potential collapsed before it reached our eyes then all the seperate particles or Photons from different objects would indeed become mixed up and it would be chaos.

Think of it in these simple terms: The object you look at transmits information about itself just like a radio wave or RF signal and your eyes are the receiver but the information is encryped so that only your eyes can receive it. We then describe the collapse of the wave function as an encryption method designed for your eyes only.

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• 1 month later...

Faced with the apparent fact that light, particles, and atoms behave as both a wave and a particle, depending on the circumstances, and the strong presumption that it cannot really be both at the same time, we have (at least) two options. On the one hand, we can deny that what we're seeing is "reality" and insist there must be some explanation for the phenomenon at a deeper level; or on the other, we can give up talking about reality altogether and elaborate some other understanding or what we can or cannot know about the universe.

Certainly, it would seem that at the microworld, there is no way we can access the “fact of the matter” or the "truth" about deep reality until some human being chooses to make a measurement. A Question: Would that indicate that the human mind builds “external reality?” Could some variant of the discredited Berkeleyean idealism be right? And if anyone thinks, “So what? That’s the microworld. It’s weird, all right, but it has nothing to do with big things like us,” they'd be wrong.

Everything is made up of quantum units, so it is possible, in principle, to fire you at the two-slit barrier, and get either a “wave you” or a “particle you” depending on what we choose to measure

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Think of it in these simple terms: The object you look at transmits information about itself just like a radio wave or RF signal and your eyes are the receiver but the information is encryped so that only your eyes can receive it. We then describe the collapse of the wave function as an encryption method designed for your eyes only.

So, that means that, photocells on a satellite don't work until we observe them? The circuits don't work until somebody tunes into the signal?

Further more... if humans had not evolved to observe it, the Universe would not exist?

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So, that means that, photocells on a satellite don't work until we observe them? The circuits don't work until somebody tunes into the signal?

Further more... if humans had not evolved to observe it, the Universe would not exist?

Being charitable, I imagine Nav just means, one cannot know the given state of such an entity until observed. That is, In any physical system, without observation, you cannot say what something is doing. That's quite a radical statement and open to much debate.

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Being charitable, I imagine Nav just means, one cannot know the given state of such an entity until observed. That is, In any physical system, without observation, you cannot say what something is doing. That's quite a radical statement and open to much debate.

So, you don't know about an object unless you observe it?

Now that is what I call common sense....... something not usually associated with interpretations of Quantum Theory.

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So, you don't know about an object unless you observe it?

Now that is what I call common sense....... something not usually associated with interpretations of Quantum Theory.

Lol,

So basically what we saying is if you stick your head in the sand and cannot see it then it does not exists.

Who would have thought that ostriches cracked quantum theory thousands of years before humans!

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• 3 weeks later...

So, that means that, photocells on a satellite don't work until we observe them? The circuits don't work until somebody tunes into the signal?

Further more... if humans had not evolved to observe it, the Universe would not exist?

The double slit experiment deals with visualization and the interaction between Photons/Electrons and the human body. It is a fact that observing sub atomic particles in certain situations collapses a wave into a particle. This phenomenon which is widely excepted and cannot be denied by the scientific fraternity has futher implications. Those implications have been ignored and cast aside for decades by mainstream science because in a nut shell they suggest that the Universe cannot exist visually unless it is observed.

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I just bought Quantum Universe by Brian Cox and Jeff Forshaw. I'll either understand this thread better or be even more confused than before!

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I'll either understand this thread better or be even more confused than before!

In the quantum world, it's not either, it's both

Apparently

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How did The Big Bang happen?....there was nothing there to observe it?

How did did life evolve from slime without somebody watching?

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