Double Slit Explanation Overdue!

[marplots]

God did it.

 

[Gord_in_Toronto]

My alternative explanation is that the double slit experiment proves that the universe is broken. Sooner or later the cosmic repairman will fix it, and then we'll be able to figure out exactly where those particles are.

Golly. Do you know what guys charge per nanosecond? There is no way anyone can afford a fix. We'll just have to live with it.

 

[temporalillusion]

I liked this video where they polled physicists on their preferred "interpretation".

 

[orange31]

to "explain" QM for example the double slit, I'm assuming you mean make a representational video of what happens on atomic or sub-atomic scale. No progress has been made in that endeavor because 1) as mentioned above, the equations do it just fine and 2) the fact that we can't play a video in our mind of the event is not a concern, actually it's not considered worthy of research funding.

Here's a simpler example; you've probably read how string theory might work mathematically but it requires 11 dimensions instead of the 4 known ones. The closest anyone comes to 'explain' that is to say the other 7 are very, very small (not joking here!) Clearly, you wouldn't waste your time trying to visualize what a 5th dimension looks like. So most physicists view the double slit in the same way. Of course, QM is experimentally proven and string is still a theory, not even testable currently.
Here's more Feynman as educator- http://www.youtube.com/watch?v=hUJfjRoxCbk

 

[Yorkie]

Over the last century or so there does not seem to have been much progress made as to explaining the results of the double slit experiment.

QUOTE]

Welcome AlfieGee.

Google 'Bian Cox night with the stars' it was on BBC iplayer so not sure you'll be able to see it but there are clips on youtube. He did a lecture at the Royal Institution of Great Britain which even a duffy like me could follow Fasinating stuff.

 

[dlorde]

Here's more Feynman as educator- http://www.youtube.com/watch?v=hUJfjRoxCbk

He's great, ain't he?

What was particularly interesting about that lecture, was that I don't remember seeing elsewhere the simple disproof of the hidden variable theory he describes; i.e. if you could discover the values of the hidden variables that determine the particle's path, you could predict which slit the particle would go through - but that would mean that you wouldn't get the interference pattern, because you can't get an interference pattern if the particle goes through one slit or the other - so there can't be any hidden variables that could tell you the path the particle will take...

So why Bell's Inequality? Was Feynman referring to a simpler form of the hidden variable theory, or something different?

 

[Myriad]

The real secret is... there is no slit.

Huh. That doesn't sound as profound as I was hoping it would.

 

[paiute]

I think this is probably the most appropriate comment to my original post. I am indeed interested in the "why" behind all the maths. It doesnt seem any of the maths is really getting anywhere as to the "why" is it ?

So... Ive got Tom Campbells My Big Toe "why" regarding the double slit. What are my other options here? Are there any that are considered plausible?

There is no 'why' in physics. There is only 'how'.

 

[Anerystos]

Try Brian Cox and Jeff Forshaw “The Quantum Universe: Everything that can happen does happen”. Allen Lane. ISBN 978-1-846-14432-5 Hardback – a paperback edition is also available.

 

[Mikemcc]

What's to explain? QM describes the probability of any particle arriving at any particular point, and this is best described as a wave. In reality, if you restrict the flow of particles, it is possible to observe the arrival of individual photons. Each provides an individual instance of observation (in tune with Heisenberg), over time it buids up to the response predicted by QM. There is no discrepancy to explain. Get over it.

 

[Anerystos]

Hey guys, this is my first post, go easy on me.

I have several problems with this post.

First, why should we “go easy on you” because “this is [your] first post”. Nobody in this forum cares whether it is or is not. Post rubbish, and take the flack. Enough people have had a go at me.

Secondly, I’ve looked at Thomas Campbell's web material. Anyone who goes down that route isn’t really worth bothering with.

I’ve just ordered a copy of Park’s “Voodoo Science”. I hope it lives up to its reviews. Maybe you should read it too.

 

[Mojo]

References to this experiment are very common, as are the detailed explanations of what happens. However, there does not seem to be much discussion as to why this is the case.

See item 17.

 

[Fizil]

Here is a great explanation of the problem with 'Why?' questions, also by Feynman:

 

[lpetrich]

A lot of efforts to interpret quantum mechanics sometimes seem to me like efforts to force it into a classical-physics mold. That seems to me because our intuitions and many of the simpler physical theories are all classical-limit ones, and also because of wanting to avoid bringing in any mathematics.

For my part, I prefer to avoid trying to interpret quantum mechanics, because of the interpretation problems I've mentioned. It can give me a headache.

Quantum mechanics is very counterintuitive, but it has very good theoretical foundations and very good experimental support, and that's usually good enough in practice.

 

[Fizil]

A lot of efforts to interpret quantum mechanics sometimes seem to me like efforts to force it into a classical-physics mold. That seems to me because our intuitions and many of the simpler physical theories are all classical-limit ones, and also because of wanting to avoid bringing in any mathematics.

I think this is absolutely key. Trying to explain something like the Double Slit Experiment in terms of our everyday experience is like asking the question "What color is ultraviolet light". Ultraviolet doesn't have a color, because color is a function of human perception and humans cannot perceive ultraviolet light. Trying to intuitively understand quantum mechanics is like trying to visualize what the color of ultraviolet light is, our brains have not evolved to deal with these things except through abstraction.

 

[godless dave]

Yes, I suppose I am asking why physics is the way it is , in this particular instance, and seems to work differently, based on whether there is an observer or not.

That's not how it works.

 

[Cuddles]

I think this is probably the most appropriate comment to my original post. I am indeed interested in the "why" behind all the maths. It doesnt seem any of the maths is really getting anywhere as to the "why" is it ?

But what does this have to do with the double slit experiment? You could just as easily ask "Why gravity?" or "Why does F = ma?" or literally any other question beginning with "why". We have a perfectly good description of what happens with the double slit experiment and what results you will get, and that's all the answer you will ever get from physics about anything. It just doesn't seem to make sense to single out this particular thing for a special "why?" when there's just nothing special about it.

 

[Modified]

But what does this have to do with the double slit experiment? You could just as easily ask "Why gravity?" or "Why does F = ma?" or literally any other question beginning with "why". We have a perfectly good description of what happens with the double slit experiment and what results you will get, and that's all the answer you will ever get from physics about anything. It just doesn't seem to make sense to single out this particular thing for a special "why?" when there's just nothing special about it.

I think the difference is that gravity and force operate at human scale, but if you throw golf balls through a wall with two slots in it, you don't get an interference pattern. For things that work the way we are familiar with, people don't feel they need an explanation, but for anything "weird", they do. It's not logical, but it's the way people think.

 

[lpetrich]

Wavelike nature of what one would expect to be particles:

Electron diffraction^WP
Neutron diffraction^WP
Fullerene Diffraction - that's soccer-ball-shaped C60 molecules

I remember a physics professor who had called a photon a "blob of light", and that seems like the closest one can get while still being nontechnical.

 

[Toontown]

Yes, I suppose I am asking why physics is the way it is , in this particular instance, and seems to work differently, based on whether there is an observer interaction or not.

The situation may be worse than you imagine.

In the first case, the electron first interacts with itself while in wave mode, forming the interference potential. Apparently self-interaction does not require being in particle mode. Nor does being forced to split into two separate self-interfering waves when it goes through the slits count as requiring a switch to particle mode. Apparently. But then it switches to particle mode when it strikes the plate while randomly varying it's particular location on the plate, thereby requiring multiple shots to form the interference pattern.



In the second case, the electron interacts with the detector at the slit by allowing itself to be counted as a particle, which (I suppose) forces it to go through the slit with the detector. Then I'm not sure what it does; it either remains a particle after being counted or switches back to wave mode and then back again to particle mode when it hits the plate.



All of which strikes me as rather odd, bordering on arbitrary complexity and Einstein-despised dice-throwing. Why not just be a damn particle all the time if you will have to be one every time you interact? What's with all the switching back and forth? Can they not move as particles? Do they have to switch to particle mode, stop, interact, switch back to wave mode, and move on?

Surely not.