Single electron interference (again)

I can only get really interested about this sort of thing when it involves killing (or not killing) a cat in a box.

Good question Jorrie I have felt that a single electron must have a single identity. Perhaps some one thought that they could get extra funding if they had a special case. Money is a powerful corrupter.

Wouldn't the act of detecting the electron by necessarily defining its location on the film cause the wave function to collapse as a particle and resulting in the wave phenomenon existing just prior to the collapse to only become visible as a statistical phenomenon as multiple waves collapse at different locations on the detector?

Well put.

If the electrons are being fired one at a time (ie: the next electron is not fired until the previous one has hit the target), then what else are they interfering with if not themselves?

If there was no interference, then each electron shoud hit the same spot instead of distributing in an interference pattern.

PS: What's in Monavoni?

Pardon me, each electron should hit one of the same two spots depending on which slit it passed through if there was no interference.

I thought a bit of the electron passed through each slit...

...and then came back together so the whole electron could hit some 'random' spot which was actually a function of the relationship between the slits and the electron's logical trajectory.

...but then I've always been a bit fuzzy on the subject.

Gordie.

What happens if the electron is schizophrenic and just can't make up it mind where to go? What if it has a dual personality and keeps arguing with its other half? How do you get to produce a single electron? Serious question. and how do you isolate it from any others that might be travelling by? I have often thought about these things but never known who to ask.

Hi Brainwave,

This quote is from the article referred to by Jorrie:

"Our experiments were carried out from beginning to end with constant and extremely low electron intensities - fewer than 1000 electrons per second - so there was no chance of finding two or more electrons in the apparatus at the same time. "

So, they didn't really have a controlled, 'one at a time' release of electrons. They just used a source that was low enough in intensity to ensure that only one electron was in the apparatus at a time. I guess a person could look up the experiment in the American Journal of Physics to learn more about how the experiment was conducted.

It isn't that the electron somehow 'split' into two pieces that travelled through each slit (that is thinking like it is a particle, which it is not), it it more like the 'electron wave' went through both slits at once. The waveform will collapse at the detector in a random location that corresponds to a probability function with fringes related to the distance between the slits.

Just curious and simplistically speaking, are saying that the electron is emitted as a particle, travels as a wave and collapses back into a particle at the detector?

I'm not sure if I have the entirely correct answer to that question, but I would say that at the quantum level it would be erroneous to think of the electron strictly as a particle at any time, during emission or at the detector. We think of a particle as having a definite position in space, but electrons (and all other quantum sized particles) don't. They only have a probability of being in any particular place at any time. This is sometimes described as a 'cloud' of probability where the denser the cloud is, the higher the probability that the electron could be located there.

The duality of the wave/particle properties of electorns is confusing and difficult to understand when we are accustomed to a world where everything we can see and touch seems to behave in the classical physical sense.

Hi SkFarmer, you wrote: "I'm not sure if I have the entirely correct answer to that question, but I would say that at the quantum level it would be erroneous to think of the electron strictly as a particle at any time, during emission or at the detector... "

You explained it very well in your posts so far, thanks! I'm still a bit unclear as to whether there is evidence of one single electron causing an interference pattern. I know that "many electrons, one at a time" implies that each electron must make some interference pattern, but there are also other possibilities, I think.

I also have great difficulty wrapping my head around the fact that the "probability cloud" can be quite spread out, but collapses instantaneously when a detection is recorded somewhere!

-J

Yet non-locality has been demonstrated. That one really messes with my mind. And it is said to act instantaneously at any astronomical distance. Ouch, brain hurting more and more.

Hi David,

This has been the interpretation since about 1930 from Niels Bohr, Werner Heisenberg and Max Born.

S

Just a thought from a bystander. If "waves", such as light, heat, radio etc., are all simply the method of transference of energy between particles and not physical in nature, in and of themselves, but yet they are able to cause effects through their "movement" or transference of energies, then wouldn't this explain the results we see from the double slit photon tests. That is, if an electron is sent out as an electron, appears as a wave as it travels, then hits the film as an electron, then it would be an electron traveling the entire distance, simply giving off illumination in the form of a wave, or simply transferring its energy outward in the form of a wave. When the light wave goes through two slits, it is still simply the transference of energy (wave and not particle) that we view as illumination and is therefore able to interfere with the other wave of light coming through the other slit, or apparently interferes with itself. When we place a dectector in one of the slits, (film), wouldn't the electromagnetic charge of the film attract the photon, thus stopping the energy transfer (light wave) on one slit, thus ending the wave interference on the other side of the slits. Additionally, as the electron pattern builds up on the film over time, wouldn't the linear pattern, along with the spacing in-between, indicate some sort of electromagnetic fields directing the electrons exactly to their destination at a spot on the film that still contains the opposite electromagnetic charge. That is, the electrons don't hit the same spot repeatedly because they are attracted electromagnetically to the film along some sort of linear and alternatingly charged fields?

The fringe pattern has nothing to do with electromagnetc charge on the film or electromagnetic fields directing the electrons.

The fringe pattern is a simple function of wave interference. The electron wave(s) eminating from each slit will either cancel each other out (the dark areas) or reinforce each other (the light areas) depending on the relative phase angle of each wave as a function of distance from each slit.

I know it is confusing - how can one electron behave like two waves, one from each slit, but the math predicts exactly the fringe pattern we observe.

Well a single electron interferes with itself. because it is amde sure that only one electron at a time is put forward. it is easier to be understood like this:
We want to show the wave behaviour of particles. If particles behave like waves, they'd be bended off. However if they do not. all of my particles will end up on the two slits on the result paper. now in the case of one slit. This happens, but when two slitsa appear we see positive and negative interference. something like of waves. Since their is nothing it could interfeir with but itself. It has to behave like a wave entering through both slits at the same time, and interfering with itself. or else the above picture could never form.