Double slit experiment - just bouncing particles?

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I saw a Youtube video that doesn't say anything but the comment shows that the uploader believes that the double slit experiment fails to show light as waves but just bouncing particles.  I'm interested to know if this is a simplistic error or a real possibility.

   

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So far, I didn't listen to the words, only looked at the image. I can't say the diagram inspires much confidence. Nor do I understand the motivation of the person who created it.

In a typical double-slit experiment (or even a single-slit one), a photon comes from a source towards a target, where it is detected and absorbed. There is no opportunity for the photon to proceed onwards and bounce back and forth like that.

But really, it doesn't seem like a step forwards when we already have abundant evidence that light is a wave, just like radio which is part of the same electromagnetic phenomena.

The difficulty of the double-slit experiment is not that it shows light is a wave. We already knew that. Nor is it the fact that light is made of particles, we knew that too (since Einstein's explanation of the photo-electric effect was dependent upon the particle nature of light). The problem it poses is that light is both a wave and a particle at the same time. This is where things become puzzling, and quantum-reality behaves very differently than our everyday experience and common-sense would expect.


edit: I'll add, there is a major blunder in the diagram. It seems to show some light reflecting off the edge of the slit, this fails to describe even basic properties of light. If we forget the slit for now, consider what happens when light encounters an edge. Imagine a beam of light is shone towards a screen, and a plain, straight-edged sheet of material is placed so as to cover half of the beam. According to this new suggested explanation, light could either proceed in a straight line and hit the screen, or be reflected from the edge of the obstacle and fall upon the illuminated part. The remainder of the screen would remain completely dark, no light would reach there. That is not what happens. Light when it meets an edge, bends around it, spilling some light into the dark area. This is diffraction.

Incidentally a similar sort of bending of a beam around an edge explains how I'm able to receive a TV signal at my aerial, although the line-of-sight-path to the transmitter is blocked by intervening hills. Radio waves exhibit diffraction, just as light waves do. (Both are part of the same electromagnetic spectrum.)
(This post was last modified: 2021-08-29, 06:25 PM by Typoz.)
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(2021-08-29, 05:03 PM)Typoz Wrote: So far, I didn't listen to the words, only looked at the image. I can't say the diagram inspires much confidence. Nor do I understand the motivation of the person who created it.

In a typical double-slit experiment (or even a single-slit one), a photon comes from a source towards a target, where it is detected and absorbed. There is no opportunity for the photon to proceed onwards and bounce back and forth like that.

But really, it doesn't seem like a step forwards when we already have abundant evidence that light is a wave, just like radio which is part of the same electromagnetic phenomena.

The difficulty of the double-slit experiment is not that it shows light is a wave. We already knew that. Nor is it the fact that light is made of particles, we knew that too (since Einstein's explanation of the photo-electric effect was dependent upon the particle nature of light). The problem it poses is that light is both a wave and a particle at the same time. This is where things become puzzling, and quantum-reality behaves very differently than our everyday experience and common-sense would expect.


edit: I'll add, there is a major blunder in the diagram. It seems to show some light reflecting off the edge of the slit, this fails to describe even basic properties of light. If we forget the slit for now, consider what happens when light encounters an edge. Imagine a beam of light is shone towards a screen, and a plain, straight-edged sheet of material is placed so as to cover half of the beam. According to this new suggested explanation, light could either proceed in a straight line and hit the screen, or be reflected from the edge of the obstacle and fall upon the illuminated part. The remainder of the screen would remain completely dark, no light would reach there. That is not what happens. Light when it meets an edge, bends around it, spilling some light into the dark area. This is diffraction.

Incidentally a similar sort of bending of a beam around an edge explains how I'm able to receive a TV signal at my aerial, although the line-of-sight-path to the transmitter is blocked by intervening hills. Radio waves exhibit diffraction, just as light waves do. (Both are part of the same electromagnetic spectrum.)

In all honesty, I didn't give it any credence on the simple grounds that if it could be that simple, I'm sure the scientists  would have come up with it.  I don't understand the technical details of QM so I just wondered what others who know more than me would think of this.
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(2021-08-30, 02:14 PM)Brian Wrote: In all honesty, I didn't give it any credence on the simple grounds that if it could be that simple, I'm sure the scientists  would have come up with it.  I don't understand the technical details of QM so I just wondered what others who know more than me would think of this.

Yes, while I'm confident that person is mistaken, I'm still puzzled as to why he expresses this view, what background or interests inspired that idea.

Of course I'd welcome any further comments from others, I'm not really deeply knowledgeable on QM. Though photography is one of my interests and understanding the properties of light is something I picked up in part from a practical necessity. We don't tend to use double-slits as part of everyday photography though, so that's from other background knowledge, building on what I learned in school many moons ago.
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I think the really important thing to understand about QM interference, is that the wavefunction isn't exactly probability, and in fact it can take on negative and positive values (or complex values) - and negative or complex probability doesn't make sense!

The corresponding probability distribution is given by Ψ * complexconjugate(Ψ), which is always positive or zero.

The reason I mention this is that when an electron wave goes through two slits, by the time it reaches the screen, the waves cancel each other out in some places and reinforce in others. If you close one slit there are places on the screen that were black that become illuminated.

Remember also that this experiment has been done with very very attenuated beams of photons/electrons and the interference pattern is the same when only one particle at a time enters the apparatus!

Another interesting thought is that light is the same kind of 'stuff' as radio waves, and they can interfere with themselves in exactly the same way.

OTH it is lovely when someone succeeds in debunking science!
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(2021-08-30, 08:26 PM)David001 Wrote: OTH it is lovely when someone succeeds in debunking science!

What does it mean to " debunk science"?
"The mind is the effect, not the cause."

Daniel Dennett
(2021-08-31, 08:42 AM)Sparky Wrote: What does it mean to " debunk science"?

To demonstrate scientifically that science is wrong? Wink
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(2021-08-31, 09:15 AM)Typoz Wrote: To demonstrate scientifically that science is wrong? Wink

I like it, but was leaning more towards:

Party.

Hard.
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(2021-08-31, 08:42 AM)Sparky Wrote: What does it mean to " debunk science"?

It means to show that some significant area of science is plain wrong.

David
(2021-08-31, 04:09 PM)David001 Wrote: It means to show that some significant area of science is plain wrong.

David

That is not "debunking science", science is a method.
If you want to show some scientific assumption is wrong, you would have to use the same scientific method to do it, otherwise you are just saying shit.
"The mind is the effect, not the cause."

Daniel Dennett
(This post was last modified: 2021-09-04, 03:05 PM by Sparky.)
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