# Could very low energy virtual particles last a very long time?

1. Apr 10, 2012

### johne1618

By looking at layman's books on physics I have picked up the idea that "virtual" particle-antiparticle pairs continually pop out of the vacuum and then back into it again.

Apparently according to the Heisenberg Uncertainty Principle the time that the particle pair can exist, $\Delta t$, is given by

$\Delta t \approx h / \Delta E$

where $\Delta E$ is the energy of the particle pair.

Is there any lower limit to $\Delta E$ like the neutrino mass? Or could the particle pair be a pair of photons with any energy?

Could $\Delta t$ be billions of years if the particle-pair has a very very low energy ?

Last edited: Apr 10, 2012
2. Apr 10, 2012

### Staff: Mentor

$\Delta E$ can be interpreted as the deviation from a proper particle energy&momentum. Particles which are very close to the properties of "real" particles can last a very long time. For pairs of particle+antiparticle with a rest mass, this quantity has to be quite large, which makes these pairs short-living.