Whats heisebergs uncertainty principle?

Question: Whats heisebergs uncertainty principle?
- Keywords:
  heiseberg,
  uncertainty principle
Asked by r3vilo to Andrew, Daniel, Hayley, Peta on 24 Nov 2011.
- Hayley Smith answered on 23 Nov 2011:
  
  Heisenbergs uncertainty principle says that the position of something and how fast this something is going, cannot be known simultaneously. This is not so important for things on the large scale, but when you get down to the quantum mechanical scale it becomes far more important. The better you know either the position or momentum of a particle the less better you know the other…
  The principle also holds true for energy and time, which has important implications when trying to understand the lifetime and energy of atomic states.
  
  There are also a few cheesey jokes relating to the uncertainty principle, and I’m full of bad jokes so have no bother or worries in sharing these with you:
  
  Heisenberg is out for a drive when he’s stopped by a traffic cop.
  The cop says, “Do you know how fast you were going?”
  Heisenberg says, “No, but I know where I am.”
  
  There’s an old hotel in Germany with a plaque on the wall:
  “Heisenberg may have slept here.”
- Daniel Scully answered on 23 Nov 2011:
  
  Heisenberg’s uncertainty principle is one of the central principles of Quantum Mechanics.
  It can be stated in different ways, but it’s the same underlying principle all the time.
  
  The most common way it’s talked about is:
  
  The more constrained a particle’s position is, the less constrained the particle’s speed.
  And the more constrained the particle’s speed, the less constrained the particle’s position.
  
  What this means is, if you were to try and measure a particle’s position very accurately you can do that. But you won’t be able to measure its speed very accurately at the same time.
  
  Likewise, you can measure a particle’s speed very accurately, but you’ll have a very poor idea of where it was when you did that.
  
  You could also measure both the particle’s speed and position moderately well.
  
  This has nothing to do with how careful or careless we are at doing the measurements. The particle itself doesn’t have a well defined position if its speed is well defined. And if the particle knows its position very well, it doesn’t know its speed. Or the particle might know both it’s speed and position, but only approximately.
  
  So it doesn’t matter how good your experiment is, you can’t know everything about a particle at the same time.
  
  Sometimes you will also see Heisenberg’s Uncertainty Principle stated in terms of energy and time, instead of speed and position. It’s the same thing though.
  
  Quantum Physics is very strange! Like I’ve said before in other Quantum Mechanics questions, no one actually understands what is actually going on in Quantum Mechanics. It’s just a theory which let’s us calculate what we’ll measure if we do a certain experiment. It doesn’t tell us how the Universe made that happen!
- Andrew Cairns answered on 23 Nov 2011:
  
  One of my lecturers once met Heisenberg in the middle of the countryside in Northern Ireland – apparently!
- Peta Foster answered on 24 Nov 2011:
  
  Andrew… did you lecturer see where he was or where he was going? 😉

Question: Whats heisebergs uncertainty principle?

Comments