Uncertainty Principle

[Ewen]

I am having difficulty understanding the uncertainty principle. I am aware that it says that you cannot acurately know both the speed and position of a particle at any given time, but I'm struggling to picture how that works.

 

I'm sure it's a very simple concept but having only read some quite deep reading on the subject I feel like I'm missing out a key element.

 

Could anyone explain it or give a for instance?

 

Thank you.

[swansont]

I am having difficulty understanding the uncertainty principle. I am aware that it says that you cannot acurately know both the speed and position of a particle at any given time' date=' but I'm struggling to picture how that works.

 

I'm sure it's a very simple concept but having only read some quite deep reading on the subject I feel like I'm missing out a key element.

 

Could anyone explain it or give a for instance?

 

Thank you.[/quote']

 

From a physical standpoint it's like this: in order to make a measurement, you must have an interaction. Any interaction will change the momentum and position of the particle you're trying to measure.

 

IOW, if you bounce a photon off of an electron, the electron will recoil, changing its position and momentum. You can only gain a limited amount of information. If you try and use a low-energy photon to minimize the recoil, the wave nature (large wavelength) means that you can't get good position information. If you use short wavelength to get good localization, you get a large amount of recoil.

[lethalfang]

From a physical standpoint it's like this: in order to make a measurement' date=' you must have an interaction. Any interaction will change the momentum and position of the particle you're trying to measure.

 

IOW, if you bounce a photon off of an electron, the electron will recoil, changing its position and momentum. You can only gain a limited amount of information. If you try and use a low-energy photon to minimize the recoil, the wave nature (large wavelength) means that you can't get good position information. If you use short wavelength to get good localization, you get a large amount of recoil.[/quote']

 

 

I don't really get quantum mechanics either. Can you explain to me how you get an interference pattern from a double slit when you only beam ONE SINGLE ELECTRON at a time?

[swansont]

I don't really get quantum mechanics either.

 

That's not a particularly exclusive club.

 

 

Can you explain to me how you get an interference pattern from a double slit when you only beam ONE SINGLE ELECTRON at a time?

 

An electron is not strictly a particle - it has a wave nature, the wave passes through both slits, and it interferes with itself. If you restrict the electron to passing through only one slit, the interference pattern disappears.