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

[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 ?

 

[mfb]

\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.