Double Slit Experiment & 'Observers', another look

There's another thread here about the double slit experiment, which frankly, is way over my head.

On a different forum, I saw some links that showed phenomena that simply made no sense to me. Either their data is skewed somehow, or something is wrong with the experiment:

See the 'trailer' (first link starts the download)
http://whatthebleep.com/trailer/

What the above trailer says is that the double slit experiment was conducted using electrons fired at 2 slits in an opaque screen. I understand wave and particles fine, I think.

Quick synopsis for those who can't or don't want to watch the video:
1. They shot electrons at a screen with 2 slits cut in it. The pattern reflected a 'wave' on the wall behind (multiple lines of electrons in a striped pattern not just two lines if it were particles).

2. They shot individual electrons at the screen. The pattern ALSO showed a 'wave' on the wall behind. How can that be possible with a single electron? There's 2 slits, and 1 electron. How would 1 electron alone be a 'wave' and enter both slits simultaneously?

3. So, to answer the above #2, someone set up an experiment where they mounted a camera to 'observe' the slits to see which hole the electron would go thru, since there's only 1 electron, but it's still forming a pattern of multiple electrons.

Result: the electron ceased to create a wave on the wall behind, instead forming a particle pattern of 2 lines.

How is that possible, in plain english please... and did they do something to the electrons, changed the speed, changed something in order to 'observe' it?

Or... do electrons really behave differently, depending on whether they are 'observed'? That makes no sense at all, so I know I'm missing something.

Here are 2 other links. This is part 1 and part 2 of videos which claim to explain Quantum Physics.

Basically, they claim that matter is a construct of our minds, because it's entirely based on subatomic particles which are in different locations at the same time. I sort of grasp the concept (but not well).

I've always known that there's a universe of space within each atom and the particles in it are really small. 'Mass' being created by the SPEED and physical limitations of the electron(s) racing around the orbit of the nucleus of proton(s) and neutron(s).

My mental image is of something that moves so fast that it can and will be at any point you try to approach it... a fast spinning 3D fan blade if you will, you can't get under or around it within it's orbit without encountering resistance, regardless of how much space exists BETWEEN the blades.

Where I get confused is the claim that each electron is DISAPPEARING and simultaneously REAPPEARING. I thought they simply spun at an incredibly fast rate, so fast that they appear solid (like the fan blade), regardless of how much space is between them (this is how well I know quantum physics... not very).

The below videos are what heightens my confusion:

http://youtube.com/watch?v=OypYJtUbMTs&sea...antum%20Physics

http://youtube.com/watch?v=4y2-lq6-h3w&sea...antum%20Physics

Can someone explain to me, in english, how this works?

You are asking a clear and very good question.
I downloaded the first video and I think I am going to take on science.
I believe I will solve the mystery of the two slit experiment of Richard Feynman.
I plan to do this with a new observation measurement of the electrons as they pass the two slits.
The problem is in their placing the cameras or test instrument's in the path of the flow of electrons.
If anyone wishes to help, I need the set up to do this.
Can anyone provide me with the electron gun?
I am on the east cost, and I will travel.
I will check at the University of New Hampshire also.

This post has been edited by boneheaded on Jul 4 2006, 01:32 PM

It all depends on uncertainty in position. A wave has large uncertainty in position, but good certainty in momentum (wavelength). Hence it will diffract from slits to form the familiar pattern.

A particle has good certainty in position, but large uncertainty in momentum. It is like a light pulse consisting of many different wavelength components.

The Tao of Physics is a good book that tries to answer these questions. read that book and then come back with the questions.

Ok, but why would the behavior of electrons change when there is an observer vs no observer during an experiment?

Is anyone familiar with the experiment and who conducted it? Did they do something to the single electron stream to make it recordable by the 'observing' camera?

They had to shine light on the two slits in order to see the electrons passing through. That is when there is no wave.

Sooo... shining light (also wave/particle) on a wave phenomenon makes it behave like a particle??

How does that make sense?

They never did this experiment without an outside factor (light?)?

Light collapses the wave function. Temporarily.

If light is the cause according to Nick, what is the big deal.
They are doing two different experiments with different results.

Hey curious 1, et al,

Trying to find "plain english" answers to your questions that lead to intuitive "mental images" might prove difficult. Physicists do not agree on a single interpretation of what is happening in the DSE. Check outhttp://en.wikipedia.org/wiki/Basics_of_quantum_mechanics and http://en.wikipedia.org/wiki/Interpretatio..._quantum_theory.

My favorite twist on the DSE is the Delayed Choice Quantum Eraser. My mind reels at the capacity of the human imagination to devise ever more elaborate experiments to try to prove (or disprove) the legitimacy (or lack thereof) of classical intuition in the QM realm!

It's not so exact, as the electron's forming a pattern of waves, not the multiple electrons. It means, the energy of electron is spread into a certain volume, distorted by the motion of electron to undulations by the same way, as the water surface becomes wavy above the fish swimming near the surface, or like ribbon bar flapping in the wind.

It means, due the motion of electron the space stops to behave like homogeneous environment, being waved perpendicular to the electron motion direction. Such inhomogeneity changes a path of particle, because the space behaves as a more dense in undulating places. The particles are spreading through space like wave (pocket), so they're have tendency to use more dense space as the path of it's direction (the wave always prefers the more dense environment for its spreading). This is a reason, why the electrons are cumulated along the same path, as the wave interference patterns on the left picture (you can click on it to see it at better resolution). And because the undulation of space doesn't depends on the presence of other electrons, such electron path distortion appears even at the case of the pass of single electron.



I suppose, most the people would understand the Aether Wave theory a much more easily, if they would become more familiar with classical wave mechanic. It's difficult to explain the particle wave properties on the real life examples, if you don't know even such examples.

The quantum wave mechanic differs from the classical one only at the point, each the energy wave increases the environment density for its spreading by such a way, the energy wave spreading becomes nonlinear. You can imagine, for example, the space is formed by energy. Each the additional energy wave just increases the total energy density, thus making it's environment more dense at this place, that's all. It's a quite easy to imagine it, considering the space is formed by the foam, the bubbles of it are collapsing to be able oscillate at higher pitch at the places with higher energy density.

This post has been edited by Zephir on Jul 5 2006, 09:31 PM

A few clarifications on the "What the Bleep Do We Know?!" trailer with the double-slit experiment. First, that isn't even in that movie. It's in the "Down the Rabbit Hole" sequel. Second, "What the Bleep Do We Know?!" is the biggest pile of excrement I've ever had the displeasure of laying my eyes on or spending my money on.

That being said, the double-slit animation is somewhat accurate. It ends with misleading information though. Your best bet is to simply read up on the experiment elsewhere and avoid the Bleep movie like the plague. It's little more than a cult propaganda movie. Google it, you'll see what I mean.

The Wikipedia articles linked to in this thread are pretty good.

Also, the Mechanical Universe educational TV series from the 80's is pretty good. You can watch it online for free at:
http://www.learner.org/resources/series42.html

- Dave

If you go to the whatthebleep.com website you will find the scientists that created that movie.

William Tiller especially.

Pat

Feynman double slit experiment fails in the assumption that only one particle is emitted at some time!

I believe that actually a short burst of particles are emitted and so different particles pass through both slits and interact after.
The experiment should be made with an improvement, with a precise count detector of how much particles are emitted at a time. This is very feasible.

For some more details visit: On Feynman double slit experiment

This post has been edited by martillo on Jul 29 2006, 06:54 PM

The sensitivity of todays CCD cameras enables to carry out such experiments with single photons as a school lab demonstration (video)..



This post has been edited by Zephir on Jul 29 2006, 07:07 PM