(c) Dr Paul Kinsler. [Acknowledgements & Feedback]
This is part of an information maze -- see the index-file for the full picture.
The physics of what an object described by quantum-mechanics is doing is defined by its wave-function which for many objects is like a wave-packet . We can mathematically describe the wave-function as either a sum of many different ideal waves or as a superposition of many different particles .
We can say either "the object has a wave-function that is a sum of waves" or "the object has a wave-function that is a sum of particles". If the wave -sum is simple, the object is acting more like a wave. If the particle -sum is simple, it is acting more like a particle.
If you try to observe the wave -like properties of an object you see a randomly chosen ideal wave part of the sum needed to make the wave-function. This tells us the momentum of the object, that is, where it is going. But a wave has no information about position - a wave is spread out in space.
If you try to observe the particle -like properties of an object you see a randomly chosen particle part of the sum needed to make the wave-function. This tells us the position of the object. But a particle has no information about momentum - it is confined to a single point in space.
This is the essence of the uncertainty-principle - if you measure the position of an object, you do not know where it is going - but measure where it is going, and you dont know where it is.
If X stands for position, P for momentum, and delta(A) for the uncertainty in a measurement of some quantity A; then the uncertainty-principle can be written as:
delta(X) . delta(P) >= h
where h is the celebrated Plancks-constant
XINDEX: quantum-mechanic, index-file.
19961128 (c) Paul Kinsler
XKEYWORD: uncertainty-principle
Email Feedback: Dr.Paul.Kinsler@physics.org
LOGBUG