This is indeed a double-slit experiment with electrons. The original reference is here:

http://dx.doi.org/10.1119/1.16104

It is touted to be the most beautiful experiment in physics.

If one believes that one electron passes through only one of the two holes, one cannot explain this experiment. This experiment shows that either the electron passes through both the holes at the same time, or while passing through one hole, is "aware" of the other hole!

To the best of my knowledge, there is no eectron double-slit experiment: if I remmember correctly, the fact that an electron has both spin and charge makes it difficult to work with. But double-slit experiments have been made with atoms and molecules, most impressively buckyballs, made of 60 carbon atoms: reference

Nairz O, Arndt M, and Zeilinger A. Quantum interference experiments with large molecules. American Journal of Physics, 2003; 71:319–325. doi:10.1119/1.1531580

As far as i can tell, the interpretation given in the video is more or less standard and valid. Particles sent one at a time do, experimentally, produce an interference pattern, which is destroyed when you attempt to observe which slit it passes through. This is also a straightforward consequence of the quantum mechanical formalism, which states that the wave function is affected in a peculiar manner---sometimes called collapse---when it interacts with a sufficiently complex system. This is maybe a point that should be clarified: it says that the measurement collapses the wave function, thus destroying interference. This is true, but it may suggest that only a measurement could have this effect. This is incorrect. Any sufficiently strong, uncontrolled interaction with a system of many particles will have the same effect, without in general leading to a measurement.

To answer your question, the experimental facts concerning double-slit interference of particles are very much as stated in the video, apart from the fact that it has not been done, as far as I know, with electrons but only with atoms and molecules. One sees an interference pattern when one sends the particles at arbitrarily low intensity towards the double-slit, but that disappears as you try to set the experiment up in such a way that you could know which slit the particle goes through.

Maybe you could be a bit more specifi as to which claims you do not believe. The video does not make many inteprettive statements,a s far as I could see, but rather, it sticks to a discussion of the facts, which are experimentally well verified.

This is indeed a double-slit experiment with electrons. The original reference is here:

http://dx.doi.org/10.1119/1.16104

It is touted to be the most beautiful experiment in physics.

If one believes that one electron passes through only one of the two holes, one cannot explain this experiment. This experiment shows that either the electron passes through both the holes at the same time, or while passing through one hole, is "aware" of the other hole!

I think you could also consider even older works by Claus Jönsson.

This publication is in German (1961): http://link.springer.com/article/10.1007%2FBF01342460

This publication is in English (1974) http://ajp.aapt.org/resource/1/ajpias/v42/i1/p4_s1

@F.Leyvraz and others: The first question came into my mind when watching the video is how well the underlined experiments are designed. The illustration of "observer" eye in the video is too far from actual experiment. Electrons, photons, or any subatomic particles are common in everything, so cross-contamination is a huge problem, I suppose. How the scientists make sure the electrons they shoot out actually reach the screen? "Solid" materials are soft and hollow after all when consider subatomic world. It can be that the electrons are from the slit or the detector. Therefore I am not convinced with the claim/conclusion that particles change behavior in a magically way if they are observed. It can be that the act of observation interferes with particles' behavior. In a worst case, it is like this "experiment":

You project your flashlight to a wall in a dark room, you see a bright circle. Next you place one of your palms in front of the light bulb so that you see no light coming out of it. Now with your palm kept like that, try to point the flashlight toward the wall. You see no more bright circle. Conclusion: Light photons are aware of your existence, they do not come out and hit the wall to make the bright circle when you try to touch them with your hand.

Clearly you can see what's wrong with above experiment and interpretation. The act of observation is like what you did with your hand in above experiment.

I am aware that this can a very ignorant question, but I can't help it :-)

Guess I also need to read the papers recommended by Tabish Qureshi and Magnus Schlösser.

One suggestion would be the more recent, than Young's two-slit experiment, by researchers at the Hitachi Advanced Research Laboratory in Tokyo, using a field-emission electron microscope. Reference - Principles of Optics (Born, Wolf, 1970) and More than a Mystery - Quantum Interference (Silverman, 1995). Silverman addresses several experimental results approaching this otherwise apparent optical anomaly without over-extending the philosophical questions arising with the observer-measurement results.

There is nothing apparent about this, there is no anomaly here and particles do not change behavior in a magical way. Young's double slit experiment is a reality. According to Feynman particles always take all possible paths.

The philosophical questions about awareness, arising from Young's double slit experiment are:

1. At which level does awareness exist?

2. Is awareness at the human brain level, or is it at the particle level?

The answer to your first question is already provided by others. It is indeed the experiment done at Hitachi, and it is a very beautiful experiment. You can see the build-up of the interference pattern after a large number of electrons have reached the detector screen. You dont see that pattern when only a few electrons reach the screen.

What it demonstrates is that the `wave property' that the electron exhibits, through the observation of the interference pattern is its intrinsic property, and as the video says, is not the result of interaction between any two electrons. It also shows that both the slits must be open to get the interference pattern even when only one electron at a time is used to build up the pattern. This is indeed the `mystery ' of quantum mechanics, which you call it so.Ther ine is anothe experiment more recently reported on this in arXiv[quant-phys] 1210.6243v1

But why on earth would you want anybody to debunk the experiment and the beautiful

idea behind it. ?

apparent (adj.) 

late 14c., from Old French aparant "evident, obvious, visible," from Latin apparentem (nominative apparens) "visible, manifest," prp. of apparere.

anomaly (n.) 

1570s, from Latin anomalia, from Greek anomalia "inequality," noun of quality from anomalos "uneven, irregular," from an-, privative prefix, "not" (see an- (1)) + homalos "even," from homos "same".

Rama,

Perhaps I was not clear. In no way was I trying to debunk Young's Double Slit Experiment. As a matter of fact as far as I'm concerned the original experiment is as meaningful as any of the more recent ones.

However, there were questions, in previous posts, on philosophical views of the experiment.

Let me expand on this:

First of all philosophy has diminished greatly, over the last century, because of science. Today philosophers are looking to physicists for guidance and ideas about the nature about the universe.

Machines, such as the LHC are being built because the human intuition is no longer capable of predicting what will be found next. Today we need things such as the LHC to show us data so that we may be able to construct new theories.

When I raised questions about awareness, I did not mean to diminish any results of Young's Double Slit Experiment.

I was trying to stimulate a conversation about awareness (or consciousness, if you will). I wrote:

The philosophical questions about awareness, arising from Young's double slit experiment are:

1. At which level does awareness exist?

2. Is awareness at the human brain level, or is it at the particle level?

However,

I need to explain that I am more interested in consciousness. Is consciousness a part of the universe? Or, is it simply in our brains. I would greatly appreciate it if anyone would like to share their opinion on this.

I understand that today's scientific community does not look kindly at such views. Well, someone has to make a move and I am making it.

In Galileo’s days, he was persecuted for new ideas as being against the church. Today, scientists are persecuted (not literally, but are having their careers in danger for new ideas). Has anything really changed, or have we just exchanged the church for academia and continue the same punishment with no introduction of freedoms?

Don,

I really appreciate the explanation, especially because of personal reasons, my French is not as good as it should be.

My Latin could be better. I had a Greek roommate in graduate school, so that language may be better than the other two. However, I have read physics journals in French and did understand them.

I have simply used the meaning of “apparent” the way we use it in basic physics courses:

The apparent weight of an object will differ from the weight of an object whenever the force of gravity acting on the object is not balanced by an equal but opposite normal force.

Meaning that apparent is not actual, but perceived or observed.

I do not htink there is an obvious connection between the double slit experiments---whether with particles or photons---and consciousness. It is true that, if we attempt to know through which slit the particle went, we shall destroy interference. But it is most emphatically not necessary for an observer to be present for the interference to be destroyed: if the experiment is done ``sloppily'', that is, if the particle is allowed to interact in an uncontrolled manner with any system having a large number of degrees of freedom as they pass the slits. This can be done in such a way that no observer gets any information out of it, yet the interference is destroyed. So iti is inaccurate to say that consciousness has an effect on interference. What is correct are the two following statements:

1) any uncontrolled interaction with a large system when the particle goes through the slits destroys interference

2) it is not possible to obtain information on the slit through which the particle passed without having such uncontrolled interaction.

F.

Results of the Double Slit Experiment have nothing to do with what you think they should be. The results are what they are and your belifes and thinking about them will not effect the outcomes.

Also, sloppy experiments are reserved for elementary school and have no place at a website such as research gate.

Vang,

Yes, a single photon can interfere with itself (as a wave) and yet terminate on something material at a point, leading everyone to adopt the familiar projectile model from classical mechanics and suggest that the photon is also a particle. This is a trap.

You ask: "What are valid interpretations of the experiment?"

I would suggest you visit this site: http://www.einsteinsmethod.com/#photon

Regards,

Paul

Late by half a year: your definite answer http://www.physics.rutgers.edu/~steves/501/links/double_slit_experiment.pdf

Larry

First of all this was the answer to the questioner, as I implicitly indicated by the remark: half a year late.

Secondly, the 2-slit experiment is the simplest example of the duality of particle and wave DESCRIPTION of matter and light. Any other test is much more difficult to grasp.

As said the way we interpret the result is by the MATHEMATICAL approach of Quantum Mechanics. The formalism incorporates the existence of an electron (mass) and light (a photon) as particle and wave simultaneously as expressed in the "wave function". Physicists do not understand this but it works out and that is why it has now been in use for 85 years to describe and explain the phenomena at the sub-microscopic level.

Another example with which it started is the simplest atom, the hydrogen atom. Its properties can/could only be understood by QM. This went thru a period of 20 years of formulating a model on concepts that were based on classical maechanics.

Summarizing, Quantum Mechanics can not be understood but (only) been applied by choosing the proper formulation which even in the case of the most recent 2-slit experiments is heavily under debate

Gentlemen,

It's very interesting to have you talking about the subject, but it is still above my current knowledge at the moment. So I will only sit back and watch. Hope you don't mind my silence.

OK

But since you started this thread and indicated the very large interest in the phenomenon, I'd very much like your first impression of this popularized intro

http://www.bottomlayer.com/bottom/reality/RealityFrame1.html

Johan

Interesting but a repetition of what you have written and posted at many other for a.

VIEWING an electron as a "real" corpuscule does not violate any concepts and so it is a very simple way of interpreting experiments done in a classical limit of collisions for instance. Science is also about simplifying concepts as to deliver these to the next generation.

Johan

What about your ideas and this in AMERICAN JOURNAL OF PHYSICS

There are no particles, there are only fields

Art Hobson

Johan

This is QED

and the publication of Hobson is here:

http://arxiv.org/ftp/arxiv/papers/1204/1204.4616.pdf

Johan

From a educational point of view I think a particle picture is still a very good starting point in mechanics and QM.

And as you know the recent double-slit publications in Science and Nature keep the dualistic view (in the title) for promotional reasons

Johan

Classical mechanics must be described in this way anyhow and there are many branches of physics that do not care about (sub)atomic or cosmic scales.

And not to forget chemistry in which molecules still feature in a semi-classical way.

Something else:

The questioner actually closed this 7 months old subject (5 days ago):

Vang Le · 9.53 · 7.38 · Aalborg University Hospital

"Gentlemen,

It's very interesting to have you talking about the subject, but it is still above my current knowledge at the moment. So I will only sit back and watch. Hope you don't mind my silence."

So why don't you open a question on this issue?

OK

When you like to discuss this way: please provide the wave-function filed of a billiard ball bouncing onto a second one

Johan

Are you serious? Did you ever play billiards and tried this at the pool-table?

Johan

I know and you know. However physics is also on application and then classical point mechanics works and not the field (no typo now) idea. Physics is unlike abstract math in which all is allowed in its own set of postulates: physics by definition MUST describe/refer to observations

Johan

How do you think this is to be taught at high school and in engineering science, /chemistry courses and why?

This double slit experiment is a creation of our imagination. Who on Earth has performed an actual double slit experiment, I mean double-slit seriously, with electrons? No one! To perform such an experiment a screen is required that cannot be penetrated by electrons! Where in this Universe can we find that screen, if all material objects are made out of atoms and, therefore, electrons! In electron diffraction experiments, by crystals and such, what guarantee do we have that the electrons that come out of the region of space where interaction takes place are the same, exactly the same I mean, that came out of the electronic canyon? No guarantee at all!

Tunnel effect... Is there any tunneling ? Where there is a potential barrier there are forces and, according to old Isaac Newton, there are bodies where the reactions to those forces are acting. Actually, check your Maxwell equations: you cannot have a maximum in electric potential unless you have a charge density. What is a charge density made off if it is not made of electrons and/or protons. We have created a labyrinth and then we just got lost in it!

When we write a Schrodinger equation like:

i\partial_t \psi = \kineticenergy \Psi + \potentialenergy \Psi,

it is implicit in our equation that our particle is part of a more complex system (There is at least another body, the one producing the force!) Where is the procedure to obtain the wave function of a part of a system from the wave system of the whole? We have no procedure at all and without that procedure, sorry, but our math is all messed!

That's great! Let's keep worshiping our beautiful quantum mechanics, for how long?

Johan

"Whether you can design equipment to accurately measure the position of this singularity and its simultaneous momentum, is a technical problem which does not form part of the laws of physics":

This is the crux of the law(s) of QM?! What (other) laws do you accept by the way with which to describe and predict physics

Johan

Thanks for your answer. As you know Heisenberg and Schroedinger's formalism are equivalent and thus the uncertainty relations between conjugate pairs of observables

Johan

You do not mention the laws of QM (Schroedinger equation etc): how else do you arrive at the description of the atoms and absorption emission of EM and nuclear phenomena

Johan

. You have presented here only your disgust about the Copenhagen school but not how to describe real entities. What is then your description of a hydrogen atom and its spectral behaviour? Heisenberg got this right and that was quite an accomplishment in his days (mind you 90 years ago and nothing replaced it)

Johan

"90 yeras ago? I doubt it."

You doubt what?

And what voodoo? The double-slit is THE experiment showing the uncertainty is of order h, see the latest on the 2-slit in Science-Nature, including weak measurements

Johan

No, we are talking about wave packets and not coherent waves because for a coherent wave position is not defined at all and can thus not be allotted to a single entity passing the slit. This is where the single particle comes into play.

As for Moesbauer: isn't it so that the whole crystal or screen takes up the full kinetic energy/momentum that is thus indefinite?

Johan

I meant undefined at the moment of collision

Back to the double-slit: there is no free-moving. There is localization between source and receptor and thus wave-packet.

Please: the double-slit is in a confinement not in outer space

Johan

The screen / crystals so heavy that the change in momentum or kinetic energy as absorbed is negligible.

As for the electron and photon these must be described by a wave-packet because they are made in the source in a certain time pass thru the slits and THEN arrive at the screen. They are not free moving entities in space.

Please realize how the experiment is done in practice

At the moment of impact the momentum is lost and before that it is not known.

The electron is characterized by a wave-packet not a single k value: then it would not originate from the cathode-source and would not bump onto the screen. It is your idea of QM that an entity can have a singularity momentum value. Yes in FREE space not in the limited confinement of the lab test

Diffraction means it has to have a finite spread in k or p

As for Voodoo try to do the slit experiment with interference and measure the p: that is voodoo

It is NOT a stationary wave but one that goes from the source to the target. you just don't have an idea of the experiment.

I agree that QM is the tool to describe the bumping at the detector per entity coliding while still interference is seen.

You are of an other opinion; fine with me

Johan

This is not going to work. you never answer one of my questions

This is not an abstract mathematical thing but an empirical lab test with REAL light electrons and about that you were never told

Johan

Such a wave does NOT have one single k; period.

Cathodixx on your book The Physics Delusion :

"Professor Johan Prins is a serious physicist who is as angry as hell.........the well-known, supposed paradox of the double-slit diffraction experiment can be simply and elegantly resolved without resorting to the paranormal metaphysics of "wave-particle duality.This book returns physics from mysticism to reality".

Why didn't you refer to this and why don't you provide this solution here then

Johan

I am sorry; I will not buy your book, but am rereading your monogram at ARXIV.

I notice that there you discuss the concept of wave packets. I accept the QM notion that one wave-packet describes one electron. Wave packets (can) have sufficiently narrow width to allow full interference for the observational number of lines at the screen behind the slits. The wave-packet (also) gives credit to the emission of single electrons in the cathode ray, one at the time, as in a gun.

Johan

A wave with a single k has an indefinite length and does not originate or finish. I refer to the double-slit setting in air or rather vacuum with only one single electron present at the time. The flight of the electron can be checked without the slits present and can be quite nicely described as a particle trajectory for instance in an electric field. A wave-packet approaches this particulate character and can explain the interference when the slits are in place

Why are you so used to a pejorative wording of people? You always behave this way?

Johan

By the way: what is a stationary electron? Where does this oxymoron exist?

Johan

@"Where have I perjured anybody?" Are you so naïve, you only have to scan back through this question and entries in other fora to find your qualifications.

@waves

Are you telling me that Young was doing his test with fully monochromatic light? Give an example of a wave with a singularity value for k. Your example of a laser (pulse) of length cT is a pulse and thus described by a wave-packet. You also know that wave-packets exhibit interference, as long as there is sufficient coherence and that is the case in the double-slit experiment.

An electron from a cathode gun does not have a single momentum associated with it where do you derive this from? I presume your own assumption that mechanics work also at the sub-atomic scale

However before I let my self be torn into your abstracies: we are discussing the double-slit experiment with a SINGLE electron. This is not a free electron but only exists between gun and screen and are localized.

I also do not appreciate your Lorentz transformation for a moving electron with a speed that is negligible to that of c.

Finally. Your picture of the atom does not work at all to describe chemistry

Johan

I agree with you on your abhorrence for the Nazi Heisenberg.

And as I said in the beginning of our discussion I certainly appreciate your concept of the electron not being a classical particle. However, as a physico-chemist the QM description of atoms and from there the semi-QM description of molecules has not been beaten by anything else yet.

johan

Go to any reference on lasers and you will find that they all have a bandwidth. however the point is in the double slit experiment one has to sure that only ONE particle is present in the system this requires certain bandwidth in k (p) to have a pulse. What is your problem with such an approach.

Also you do not answer where a confined wave is found with ONE k value

@.http://www.springer.com/chemistry/theoretical+and+computational+chemistry/book/978-94-007-7577-0>;:

Springer page says: "out of print"

Johan

Example of your attitude: in your last sentence

"I am beginning to suspect that your background in physics and chemistry is very deficient, indeed" says WHO? So what are your credentials pray tell to judge.

Johan

Because your questions are not related to the subject! So I do not answer these, period. I also do not reply (in ResearchGate) about my personal hobbies. The issue is that YOU do not reply on the issue at stake: the double-slit single particle interference pattern.

Went to your site; am not impressed; see many monographs

Joha

You know better: a wave-packet also interferes and a fully monochromatic wave does not exist and it canot represent a single electron

Johan

You keep on mentioning coherence: does not exist (in physics) there is always a line-width meaning a SUPERPOSITION of waves