# Double Slit--closing a slit while particle is in flight

1. Apr 19, 2015

### tpeabody

I'd like to understand the wave particle duality and how information traverses space further within the double slit experiment.

Let's assume we have two slits, A and B. A is higher up then B, and an electron moves to the right through the slits and hits a final screen.

While the electron is in flight towards the slits, let's say slit B is closed; and the information of slit B being closed will not reach the electron until it hits the final screen. What would the probability distribution look like for the final screen?

2. Apr 19, 2015

### Simon Bridge

There is no such thing as woave-partical duality. The words are a label for a confusion that results from insisting on using outdated models to describe phenomenon on a quantum scale.

The standard 2-slit experiment... with a single particle traversing the apparatus at a time.

...after the electron has hit the screen, the probability distribution is a spike where the electron hit. The probability of the electron being detected at a particular place (i.e. inside the detector) is 1 and elsewhere it is 0.

Before the electron hits the screen, the probability distribution would be that of a single slit provided there was no chance that the electron could have reached the slits before one slit was closed.

The best place to start properly understanding this, if you are serious, would be the Feynman QED lectures:
http://www.vega.org.uk/video/subseries/8
... see all 8 lectures in the series.

Last edited: Apr 19, 2015
3. Apr 19, 2015

### tpeabody

4. Apr 19, 2015

### StevieTNZ

5. Apr 19, 2015

### Simon Bridge

You mean you want to know the resulting interference pattern built up over many repititions of the experiment.

It will follow the pattern for a single slit, provided there was no possibility that the electron could have passed through the other slit before it was closed.

Aside. Off the description, not all the source electrons will arrive at the screen.

The electron knows nothing of the setup that it does not interact with.

Do you mean that the electron passes through a slit and then the other slit us closed?

It doesn't. You can do the experiment with light so now there is no possibility that the screen knows the outcome before it happens and it still comes out the same.

It is unclear how you think that information may arrive at the screen ahead of the electron in some places and not in others. Definitely see the lecture series, preferably before replying: Feynman anticipates many of your questions.

Last edited: Apr 19, 2015
6. Jul 4, 2016

### tpeabody

I am looking for experimental data along the lines of the following experiment.

Also, does anyone have any more links to experiments as the above? Basically looking for as much data as possible on pilot-wave ( debroglie-bohm qm theories. ) experiments.

Also, can anyone recommend a good book on pilot-wave or debroglie-bohm theory?

I am posting here as this is an answer to my own question.

7. Jul 4, 2016

### StevieTNZ

Do remember that experiment used weak measurements, https://en.wikipedia.org/wiki/Weak_measurement, so the conclusion reached may not actually be the case.