B The wave function of the electron doesn't collapse when passing through air?

[cosmanino2050]

TL;DR Summary

Why the wave function of the electron in the double slit experiment doesn't collapse when it passes through air (interacting with its molecules) before reaching the screen, showing the interference pattern?

Why the wave function of the electron in the double slit experiment doesn't collapse when it passes through air (interacting with its molecules) before reaching the screen, showing the interference pattern?

 

[Doc Al]

Such experiments are typically done in a vacuum.

 

[Nugatory]

Why the wave function of the electron in the double slit experiment doesn't collapse when it passes through air (interacting with its molecules) before reaching the screen, showing the interference pattern?

As @Doc Al says, experiments with electrons are usually done in a vacuum, precisely because otherwise the electrons would interact with the air molecules that they encounter. The vacuum pumps and vacuum chambers are expensive and hard to maintain so we generally try not to use electrons in our experiments if we can use photons (which don't interact strongly with air and can be moved around in fiber optic cables) instead.

 

[martinbn]

Why the wave function of the electron in the double slit experiment doesn't collapse when it passes through air (interacting with its molecules) before reaching the screen, showing the interference pattern?

Just to stress that it is not the wave function that passes. It is the electron.

 

[PeterDonis]

Moderator's note: An off topic and rather contentious subthread has been deleted.

 

[AlexB23]

Quick question folks. What would the weakest vacuum pressure (or air pressure) be that would allow the electron wave function to collapse in a double slit experiment? 0.1 kPa, 1 kPa, 10 kPa?

 

[DaveE]

Quick question folks. What would the weakest vacuum pressure (or air pressure) be that would allow the electron wave function to collapse in a double slit experiment? 0.1 kPa, 1 kPa, 10 kPa?

It's about the probability that a single electron interacts with something, like air molecules. There is no minimum. Even in a vacuum the electron could interact with a passing cosmic ray.

 

[AlexB23]

It's about the probability that a single electron interacts with something, like air molecules. There is no minimum. Even in a vacuum the electron could interact with a passing cosmic ray.

That is true. But when will roughly 50% of electrons be disrupted?

 

[DaveE]

That is true. But when will roughly 50% of electrons be disrupted?

IDK. I'm not qualified or inclined to solve this for you. But I would take a serious look at the classical limit.
Suppose King Kong is shaking a really big box full of baseballs and an MLB pitcher throws one at 100mph through the box. What are the chances that there's a collision. I'm not sure pressure is the only relevant constraint. What about path length, temperature, etc. Maybe density is more useful? Maybe search google for "mean free path".

 

[AlexB23]

IDK. I'm not qualified or inclined to solve this for you. But I would take a serious look at the classical limit.
Suppose King Kong is shaking a really big box full of baseballs and an MLB pitcher throws one at 100mph through the box. What are the chances that there's a collision. I'm not sure pressure is the only relevant constraint. What about path length, temperature, etc. Maybe density is more useful? Maybe search google for "mean free path".

Thank you. Yeah, density is temperature and pressure dependant. I have heard of mean free path. Pretty complex stuff if you ask me.