The double slit experiment is magic

[bombus]

The double slit experiment is indistinguishable from magic, and yet some people are so certain magic does not exist!

 

 

 

 

Mod note: thread split off from magic or not

Edited September 1, 2009 by swansont

[the tree]

The double slit experiment is indistinguishable from magic

Can you explain that? The results of the double slit experiment are pretty well understood.

[ydoaPs]

The double slit experiment is indistinguishable from magic, and yet some people are so certain magic does not exist!

 

Particle entanglement is MAGIC and a MIRACEL!

[bombus]

Can you explain that? The results of the double slit experiment are pretty well understood.

 

Yes I can. The results of the double slit experiment have confounded everyone since their discovery and are not understood in the slightest.

 

Anyone who says that they understand Quantum Mechanics does not understand Quantum Mechanics-Richard Feynman

 

If you understand the results, would you please explain them to us? I am sure the scientific community would love to hear the answer. You'd get a Nobel Prize for this one

Edited September 1, 2009 by bombus

[swansont]

Argument from authority aside, the quote is not the same as "nobody understands anything about QM," which is how you are presenting it. QM is a very broad and deep subject, and any person's understanding of it is incomplete. It is less complete for some than for others.

 

Interference is a fairly straightforward concept; the real eye-opener is the evidence that the photon interferes with itself, because you get an interference pattern even if you send in light one photon at a time.

[Edtharan]

Yes I can. The results of the double slit experiment have confounded everyone since their discovery and are not understood in the slightest.

"Not in the slightest"? At best, that is an exaggeration.

 

They do understand it, it is only when you try to understand it in terms of macroscopic behaviours that it doesn't make sense.

 

If you don't try to visualise it as macroscopic behaviours, or try to use a macroscopic analogy, and instead try to understand it in its own terms, then you will be able to understand it.

 

In QM "Things" (note" "things" is a macroscopic term) don't have a defined place like we think they should.

 

Such"objects" like photons, or even electrons and protons, don't have a defined place until something interacts with (observes) it. It is only when something interacts with something else that they both get a defined location (and other parameters) within their system.

 

If you don't try to interact with a particular aspect of an object, then that aspects becomes more uncertain. It is also a bit like a See-saw (another macroscopic analogy so it is not a true description of what happens but will help you to understand it to a point without the need for complex mathematics). There are linked properties of objects that if you detect one of these linked properties, you make the other uncertain.

 

So if you detect the Position of a QM object, then its energy becomes uncertain. But then, if you detect the energy, the position becomes uncertain.

 

Using an other macroscopic analogy (which again is not how it happens, but will help you understand it without the mathematics): This is a bit like a camera and a pool table.

 

IF you roll pool balls around on the pool table, you can use a camer a to take a photo of it. If the photo has a fast shutter speed, then you get a nice clear image of the pool ball. the problem is that the pool ball does not seem to be moving around. You can know the position of the ball very accurately, but you don't know how it is moving (the energy).

 

But if you then give the camera a slow shutter speed, the camera is shutter is open for a while and the pool ball leaves a track as it moves. But because the ball existed at all points on that track, you can't actually say that it is at any particular point on that track (it exists at all points on the track). You can know the energy of the pool ball, but the position of the ball is uncertain.

 

Now, this differs from actual QM objects because when you make a measurement of a QM object (say an electron), you change the properties of the object you are examining. To see an object, you have to interact with it (shine light on to it, but because you don't know the properties of the objects you are using to detect the object (photons) when the objects itneract the properties are exchanged, and so you no longer know the new properties of the object.

 

In QM, unlike macroscopic objects, this uncertainty has real physical existence. This actual existence of uncertainty as a real physical property means that an uncertainty in the position of an object really means that its position is "smeared out".

 

This smearing can mean that the macroscopic notion of a particle only being able to pass through one slit or the other does not actually apply to the QM world. It is therefore perfectly possible for a photon, electron (or even an entire atom) to pass through both slits.

 

The result of this is that the particle (or even atom) interferes with itself. This interference is with the uncertainty of the object. Certain zones become less likely and other become more likely. The level of uncertainty is still the same, it is just that if it can possibly be in one place, then it can not be in another.

 

At the far end of the 2 slit experiment is a device that directly interacts with the particle to detect its position. When this occurs, the size uncertainty is reduced to a small point (where it is detected), but because of the uncertainty as it passed through the slits, there are some places it can't possibly be detected and others that have an increased chance of detecting it there.

 

The 2 slit experiment is not magic at all, it is well understood (even to a non-scientist like me), but you just have to abandon your macroscopic preconceptions about how it works.

[Sisyphus]

There are two claims here, and I think they're both pretty clearly false:

 

1) We don't understand anything about how QM works.

 

2) Things we don't understand are "magic."

 

Does that about sum it up?

[John Cuthber]

Very few things are as well studied, and therefore as well understood, as the 2 slits experiment.

According the the bizzare definition used in the OP everything is "magic" which makes the term pretty useless

[bombus]

Firstly, I didn't say that the double slit experiment is magic - i said it was indistinguishable from magic. I was giving a nod to that famous quote from Arthur C Clarke about technology. Also, this was part of a discussion about magic so is now out of context. (Has a moderator has decided to be mischevious at my expense?) In the original thread I was suggesting a possible scientific explanation for the phenomenon some call 'magic' and therefore challenging the certainty that some have that it does not exist. I am not saying magic DOES exist, but that I am open minded to the idea that some things that could be described as magic might exist in some form and have a scientific explanation.

 

I really think this should have stayed in the original thread.

 

Now to answer some of the replies...

 

Argument from authority aside, the quote is not the same as "nobody understands anything about QM," which is how you are presenting it.

 

That's not what I have said nor implied. I am saying (essentially) that the RESULTS of the double slit expt still confound science.

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The real eye-opener is the evidence that the photon interferes with itself, because you get an interference pattern even if you send in light one photon at a time.

 

Indeed. That's the exact thing I am referring to.

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Edtharan

 

Your post is a great example of avoiding trying to understand what is ACTUALLY happening. Our inability to undertand what exactly is happening below a certain scale is not a scientific explanation - It's a lack of one. You are simply saying that we should just accept that it's wierd.

 

You might as well be saying 'it's just magic - nothing wierd'.

 

Can you give me a scientific explanation of what ACTUALLY happens? Why does one superposition become the actual reality over other potential realities?

 

There are some explanations emerging that may explain what is happening - i.e., quantum information may be able to travel back in time and so affect the present - but this is by no means agreed and would possibly be considered pseudoscience on this forum (???). You tell me!

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There are two claims here, and I think they're both pretty clearly false:

 

1) We don't understand anything about how QM works.

2) Things we don't understand are "magic."

 

Does that about sum it up?

 

No, on both counts. I am not saying either of those things.

Edited September 2, 2009 by bombus
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[swansont]

Firstly, I didn't say that the double slit experiment is magic - i said it was indistinguishable from magic. I was giving a nod to that famous quote from Arthur C Clarke about technology. Also, this was part of a discussion about magic so is now out of context. (Has a moderator has decided to be mischevious at my expense?)

 

Almost certainly. I'll bet the bastard didn't even put a moderator note in, linking/explaining where the posts came from.

 

In the original thread I was suggesting a possible scientific explanation for the phenomenon some call 'magic' and therefore challenging the certainty that some have that it does not exist. I am not saying magic DOES exist, but that I am open minded to the idea that some things that could be described as magic might exist in some form and have a scientific explanation.

 

I really think this should have stayed in the original thread.

 

If you had explained it this way, perhaps it would have. But you didn't, you said QM was indistinguishable from magic, and followed it up with later statements on QM.

 

 

Now to answer some of the replies...

 

 

 

That's not what I have said nor implied. I am saying (essentially) that the RESULTS of the double slit expt still confound science.

 

 

Indeed. That's the exact thing I am referring to.

 

And yet it doesn't confound science.

 

 

Edtharan

 

Your post is a great example of avoiding trying to understand what is ACTUALLY happening. Our inability to undertand what exactly is happening below a certain scale is not a scientific explanation - It's a lack of one. You are simply saying that we should just accept that it's wierd.

 

You might as well be saying 'it's just magic - nothing wierd'.

 

Can you give me a scientific explanation of what ACTUALLY happens? Why does one superposition become the actual reality over other potential realities?

 

There are some explanations emerging that may explain what is happening - i.e., quantum information may be able to travel back in time and so affect the present - but this is by no means agreed and would possibly be considered pseudoscience on this forum (???). You tell me!

 

"Weird" is subjective. Nature has no obligation to be understandable to you.

 

No, on both counts. I am not saying either of those things.

 

You fooled several of us. How is one to interpret "not understood in the slightest" as something else?

[John Cuthber]

As far as I am concerned saying "A" is indistinguishable from "B" is indistingiushable from saying that "A" is the same as "B".

 

What's the difference?

[bombus]

As far as I am concerned saying "A" is indistinguishable from "B" is indistingiushable from saying that "A" is the same as "B".

 

What's the difference?

 

Are you being deliberately obtuse? Is Arthur C Clarke's quote really that impenetrable to you?

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Almost certainly. I'll bet the bastard didn't even put a moderator note in, linking/explaining where the posts came from.

 

And he misquoted me in the thread title.

 

If you had explained it this way, perhaps it would have. But you didn't, you said QM was indistinguishable from magic, and followed it up with later statements on QM.

 

 

If people had actually read what I had written there would have been no confusion.

 

And yet it doesn't confound science.

I disagree, but if you insist lets start with a simple one. Can you explain to me how a single photon interferes with itself please.

 

"Weird" is subjective. Nature has no obligation to be understandable to you.

Doesn't every scientist agree that the results are wierd? If not please explain them to me.

 

I never said nature did have any obligation to be understandable to me - or anyone for that matter. Are you agreeing that science can't explain the results?

 

You fooled several of us. How is one to interpret "not understood in the slightest" as something else?

I maintain that the results of QM are not understood (as in can be explained according to 'standard' scientific theory) in the slightest.

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[insane_alien]

I maintain that the results of QM are not understood (as in can be explained according to 'standard' scientific theory) in the slightest.

 

do you mean 'cannot be understood using classical physics'?

 

if so then of course its not. this is like saying the results of gravitation are not understood in the slightest by the theory of ohmic resistance.

[bombus]

do you mean 'cannot be understood using classical physics'?

 

if so then of course its not. this is like saying the results of gravitation are not understood in the slightest by the theory of ohmic resistance.

 

Classical Physics of course breaks down below a certain scale.

 

Quantum Mechanics can then be used, which can make predictions about wave/particle behaviour based on statistical probability. However, there is no agreed or proven explanation for what actually occurs. We can make CPU's, lasers, solid state electronics etc. work by using statistical probabilities, but cannot explain what actually happens without resorting to seemingly bizarre explanations (which may or may not be true). Quantum Theory (as opposed to Quantum Mechanics - if a such a distinction is allowed) has come up with a number of possible explanations which I think most would agree are pretty damned wierd and are not universally accepted.

 

It might as well be 'magic' for all we actually know about what actually happens, or possibly gives an explanation to some phenomena classed as 'magic'.

Edited September 3, 2009 by bombus

[insane_alien]

actually, we do know what happens in all those cases. it just seems that it is you that is unaware of what happens and extrapolating from that that noone else does either.

 

this is called 'arguement from ignorance' and is a logical fallacy

[Sisyphus]

The problem seems to be just that we are macroscopic objects whose direct experience is limited to objects within a few orders of magnitude as ourselves - the realm of close-enough predictions by classical physics. So it's natural to insist on thinking of things that way, in which case QM is totally weird. "How does it do that?" Well, how do classical objects do what they do? How do you only walk through one door, and never seem to interfere with yourself? It's just a matter of what seems "normal."

 

And I still don't know what definition of "magic" is being used in this discussion.

[swansont]

I disagree, but if you insist lets start with a simple one. Can you explain to me how a single photon interferes with itself please.

 

That's not what you asked. You asked for the explanation of the double slit, and it's interference. And we still see it with a single photon. Asking how a photon interferes with itself is a different question. But a photon is a quantum of energy, and you only notice this so-called particle property when it interacts with the detector. While in transit, it's still a wave. Waves interfere.

 

 

Doesn't every scientist agree that the results are wierd? If not please explain them to me.

 

I never said nature did have any obligation to be understandable to me - or anyone for that matter. Are you agreeing that science can't explain the results?

 

 

I maintain that the results of QM are not understood (as in can be explained according to 'standard' scientific theory) in the slightest.

 

What are you meaning by "standard" scientific theory? QM is the accepted theory, and incorporates this phenomenon. Therefore, it can be explained by "standard" theory.

 

QM is not, however, synonymous with the interpretations of QM.

[bombus]

actually, we do know what happens in all those cases. it just seems that it is you that is unaware of what happens and extrapolating from that that noone else does either.

 

this is called 'arguement from ignorance' and is a logical fallacy

 

I know what 'happens' in the double slit experiment - but cannot explain how - so can't really explain anything at all apart from what the results are, which anyone can do.

 

It's not really a scientific explanation though is it? It's nothing more than a description of an experiment. We have the Method, Results, but are awaiting the Conclusion.

 

I don't want this to become an argument about semantics.

 

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That's not what you asked. You asked for the explanation of the double slit, and it's interference. And we still see it with a single photon. Asking how a photon interferes with itself is a different question. But a photon is a quantum of energy, and you only notice this so-called particle property when it interacts with the detector. While in transit, it's still a wave. Waves interfere.

 

I think you are deliberately trying to misunderstand me. I think you know precisely what I am getting at - even if photons or electrons are shot one at a time an interference pattern builds up if both slits are open. Can you explain this?

 

What are you meaning by "standard" scientific theory? QM is the accepted theory, and incorporates this phenomenon. Therefore, it can be explained by "standard" theory.QM is not, however, synonymous with the interpretations of QM.

 

Well obviously I am talking about the interpretations! I find it hard to believe you haven't the intelligence to realise this. What are the Conclusions? All scientific experiments should really have Conclusions - what are yours in this case?

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The problem seems to be just that we are macroscopic objects whose direct experience is limited to objects within a few orders of magnitude as ourselves - the realm of close-enough predictions by classical physics. So it's natural to insist on thinking of things that way, in which case QM is totally weird. "How does it do that?" Well, how do classical objects do what they do? How do you only walk through one door, and never seem to interfere with yourself? It's just a matter of what seems "normal."

 

And I still don't know what definition of "magic" is being used in this discussion.

 

Well I know how macroscopic objects act. How sub-atomic particles act seems to defy logic and run counter to much that we understand about reality.

 

The problem with the definition of magic is due to this thread being started from the old one. It should have remained in the other thread. See my earlier post in this thread

Edited September 3, 2009 by bombus
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[Edtharan]

I know what 'happens' in the double slit experiment - but cannot explain how - so can't really explain anything at all apart from what the results are, which anyone can do.

It doesn't matter if you (or even if I can) explain everything that occurs in the double slit experiment.

 

Actually, lets look at an other example:

 

Can you explain what occurs when a See Saw (teetertotter) works?

 

You might try with basic Newtonian Mechanics. But do you understand why they work? No, then See Saws are indistinguishable form magic.

 

But, if someone asks you how one works, you don't just say "Magic".

 

That is because you know it isn't magic. That there is an explanation of it (even if you don't know it yourself or can articulate it).

 

So is it important that you know the precise explanation of how a See Saw works for it not to be magic? No.

 

What is important is that there is one and that you can understand the results of that theory.

 

It's not really a scientific explanation though is it? It's nothing more than a description of an experiment. We have the Method, Results, but are awaiting the Conclusion.

No, the phenomena of interference is understood and has to do with the properties of waves (not just photons as the same theory explains interference in water and other cases as well).

 

You were asking for an explanation of the Double slit experiment. Is it surprising then that the explanation you got referred to the double slit experiment?

I think you are deliberately trying to misunderstand me. I think you know precisely what I am getting at - even if photons or electrons are shot one at a time an interference pattern builds up if both slits are open. Can you explain this?

Yes. QM is not weird, it is classical mechanics that is weird.

 

The universe operates at its fundamental level in a QM way. What is weird is that we get Classical Mechanics out of that.

 

If you try to use Classical Mechanics to understand QM, then you find it hard to understand. But if you use QM in an attempt to understand CM, then you find it much easier (but still weird).

 

Look at in this way. In the snow you wear large and bulky gloves. But if you were to try and sew gloves together while wearing those gloves, then you would find it very difficult to do and you would struggle to understand how someone could sew in an intricate way with such large gloves on. However, if you take those gloves off, it becomes easier to sew and you now can understand how someone could sew fine thread.

 

Classical mechanics are like the gloves, if you just wear those gloves, the fine thread is not all that "understandable". But if you take the gloves off (and look at it from the fundamental level) then it is much easier to understand.

 

What you are (repeatedly) doing is trying to understand QM from the CM level. It just can't be done. The "gloves" are just too think and don't allow us to grasp the "thread" properly. The universe does not operate from the classical level, so there is no reason (except egotism of our scale) to assume that CM would allow you to understand QM.

 

The explanation is that the location of a photon (electron or other particle too) is not a point (that classical and wrong mechanics would lead us to) but is spread out. Only when it interacts with another particle doe that location become fixed (as compared to the photon/particle system).

 

It comes down to a very simple thing:

 

If you interact with something, then you change what you interact with. As you can't interact with yourself, you can never know the precise outcomes of your interaction.

 

As Uncertainty has a real physical effect (and why not, why should energy, or charge, or spin have a real physical effect?), this uncertainty causes the location of a particle to spread out.

 

Uncertainty is actually a wave, so it is no surprise then that the uncertainty in location of a particle can interfere with itself or other waves.

 

Well I know how macroscopic objects act. How sub-atomic particles act seems to defy logic and run counter to much that we understand about reality.

As I said. We only assume that Macroscopic objects are the norm because we ourselves are macroscopic. The fundamental objects in the universe are not macroscopic, so why should they be expected to operate in terms of macroscopic objects. It is macroscopic egotism to think so.

 

If you know about complex systems, then you would know that in complex systems, the behaviour of the system as a whole is not necessarily the same as the smallest parts of the system.

 

Think about this: Is there anything in the operation of a resistor that explainas your word processor? Is there anything in the operation of your word processor that explains how a resistor works?

 

You computer uses resistors in its operation, and your word processor uses your computer. It is possible, with a full explanation of how electronics works, and a full description of the electrical state of a computer, to explain how your word processor works. But if you just try to use the operation of your word processor to explain how a resistor works, then you will never do it.

 

It is the same with Classical Mechanics and Quantum Mechanics. Why should the operation of Classical Mechanics (the word processor) be able to explain how Quantum Mechanics (the resistor) works?

 

Armed with a full description of Quantum Mechanics, and a full description of the Quantum state of the system, then QM can explain the operation of Classical Mechanics. Just as with the resistor and the word processor.

[bombus]

Ethdaran

 

What you seem to be saying then is that science cannot explain CM either - as it's all based on QM.

 

The conclusion of your argument would seem to be that everything is indistinguishable from magic?

 

That's quite a bit further than I would be prepared to go:D

Edited September 6, 2009 by bombus

[Edtharan]

Ethdaran

 

What you seem to be saying then is that science cannot explain CM either - as it's all based on QM.

 

The conclusion of your argument would seem to be that everything is indistinguishable from magic?

 

That's quite a bit further than I would be prepared to go:D

No. I am definitly not saying that at all.

 

What I am saying is that Quantum Mechanics can not be understood by using Classical Mechanics.

 

QM can be understood in an of itself, but not though Classical Mechanics.

 

Classical Mechanics is a consequence of Quantum Mechanics, not the result. Just like your word processor is the consequence of how the electronics operate in your computer.

 

You can't determine how the electronics work in your computer by just studying the operation of your word processor. You need to open up your computer and study its operation with knowledge of electronics.

 

As I said: Classical Mechanics is the same as the Word Processor. The "operation" of QM create the result of Classical Mechanics.

 

Think of Classical Mechanics as the output of a computer program and you are closer to understanding that Classical Mechanics is not how the universe operates.

 

You are trying to understand how the universe operates by only looking at how your "Word Processor" works. When you abandon that futile task and learn QM, then you will begin to understand how QM operate and how CM is created from them.

 

I don't know how many times this has to be said to you: You are thinking about this incorrectly.

 

If you understand QM using QM then you actually can understand how it operates. If you try to (futilely) understand QM from a CM position, then you will never understand QM.