# Heisenberg's principle

1. Dec 13, 2008

### pi.rootpi

Hi, I've a doubt!
The principle says that we cannot find simultaneity the position and the momentum of a particle, I understand this because if I haven't understood bad it's because to find the position of a particle we need to trhow photons to it (and more and more) as much as we want to be precis and this changes its velocity.

The one i don't understant is the one of time and energy. Why can't we find both exactly?

Thanks!!!!

2. Dec 13, 2008

### Dmitry67

Energy defines how particle interact with the others. So you need to give it some time to interact.

3. Dec 13, 2008

### mlcen

Energy is a kind of cumulation effect. If you want to survey the energy of a system accurately, you need some time. So the time becomes inaccurate.

4. Dec 13, 2008

### GDogg

It's the inequality obeyed by the deviation of the energy distibution of the states forming a wave packet that evolves with a wave function $\Psi(t)$. In other words, a relation between the energy distribution of a wave packet and the characteristic time it takes to deform.

The interpretation stating that "the more accurately you want to measure the energy of a system, the more time it takes to measure" was shown to be wrong by Aharonov and Bohm in Phys. Rev. 122, 1649 (1961).

Last edited: Dec 13, 2008