Uncertainty Principle and lifetime

[Niles]

Hi all

Please take a look here (just read the first paragraph): http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/parlif.html

I am a little uncertain of why it is that we equal the spread in time ∆t to the lifetime of the excited state (in the above link they denote the lifetime by Γ). What allows us to do this?

[Niles]

Ok, this explains it pretty well: http://en.wikipedia.org/wiki/Uncertainty_principle#Energy-time_uncertainty_principle

Thanks.