If the vacuum energy is lower between two closely-spaced plates, what effect, if any, does this have on quantum processes such as radioactive decay or the lifetime of unstable particles such as the muon.

For example, if I were to send a muon through this space, would the changed vacuum energy affect its lifetime?.

Alternatively, if a sample of a radioactive substance was placed within the region between the plates, would the half-life be altered in any way due to the changed vacuum energy.

I ask this because I understand that certain physical processes such as the spontaneous emission of a photon from an atom in an excited state is the consequence of interaction with vacuum fluctuations. Therefore it seems logical to suppose that this applies to other quantum processes.

Hi AndrewM,

"I ask this because I understand that certain physical processes such as the spontaneous emission of a photon from an atom in an excited state is the consequence of interaction with vacuum fluctuations."

That I don't understand :) ... care to elaborate or post a reference ?

Bye!

Crisp

What I meant was that I understand that an electron orbiting an atom in an excited state will at some point in time transition back to a lower-energy state, emitting a photon in the process and that this process is triggered by vacuum fluctuations.

To quote from V.Christiano, who puts it more elegantly than I can.

In a fluorescent lamp, the atoms are put into excited states by means of an electrical discharge. Originally it was thought that spontaneous emission of electromagnetic radiation was simply a property of atoms, but later it was realized that this so-called spontaneous emission is really not so spontaneous. It is actually stimulated by the background fluctuations that are continually
agitating the atoms. If those vacuum modes that are causing the atom to emit spontaneously are missing, then the atom will stay in its excited state. It has been observed that the spontaneous emission time for an atom in a specially constructed cavity can be much greater than for one in free space, up to a factor of 42. Similarly, in a properly constructed cavity one can reduce the spontaneous emission time by a factor of 500 and speed atomic transitions. Spontaneous emission occurs only because the background, the vacuum, is always fluctuating. Vision, which depends upon spontaneous emission, is possible only because the background vacuum fluctuations are jiggling the atoms all the time. If someone could "pull the plug" on vacuum fluctuations, we would not see anything.

Hum,
I see your point.

If the quantum energy level coincided with a `blocked` frequency/harmonic ( explain later) then that decay process would effectively be blocked?

But if they didn`t match exactly with the missing virtual particles then they would decay...

To explain my view on the casimir effect , is to think of the virtual particles between the plates as `frequencies`....
Only certain frequencies can exist ( the others are destructively interfered) that correspond to the size of the gap.

Thus there are more virtual particles on the out-side than inside....causing negative energy.

Anyone else?

Thus there are more virtual particles on the out-side than inside....causing negative energy.

You can explain the gravity in the same way.

Besides I think that Crisp is correct that some fluctuations in the vacuum itself are needed for the incidental natural processes . This fluctuations represents accualy the zero-point energy of the vacuum. They are needed not only for the electron spontaneous emission but and for radioactive decay, without the zero-point energy every excited state will live forever. Thus is because energy is needed for every transition . even when it is between meta-stable and stable states .