# Wave propagation, resonance and collapse

1. Jun 6, 2011

### yeshi

Hello,

there is a subject of wave propagation and collapse that has plagued me for some time, and although i must have heard about it, my memories are probably skewed ( i studied EE and had high frequency, physics of materials and nuclear/quantum physics sometime in 1970s :) as subjects). In the online textbooks i was unable to find an answer. My views are somewhat of an EE, that holds fast to antenna and fields, etc. :tongue:

Question:
When the wave propagates - let's say a single photon - it is my understanding that it will discharge when a resonant candidate (absorber) is reached in space(time) and will ionise an atom by changing an electron in some of its orbitals.

If we look at a wave as a propagating phenomenon traveling from the emitter at speed c (media dependant) then it has a wavefront, maybe an expanding sphere in vacuum or some other form.

Does it mean that the wave can collapse only if the wavefront meets a potential recipient (atom) on its expansion, or can the discharge happen WITHIN the already transversed volume of the field? In other words, is the wave collapse always happening when the absorber is reached along the wavefront expansion?

thank you in advance

2. Jun 6, 2011

### Bill_K

yeshi, The wavefunction that we talk about, ψ(x, t), is the probability amplitude for finding the particle at point x at time t. An interaction may take place anywhere that ψ(x, t) is nonzero. The other terms you use, discharge and resonant absorber, make the process sound way too continuous and way too classical. It is not like a wave gradually transferring energy to a receiving antenna. The interaction, if it occurs, occurs at a single point at a single instant.

3. Jun 6, 2011

### yeshi

excellent,

so the interaction can occur at a point within the volume already traversed (as the wavefuncion is nonzero within all of the field (aka volume)). Thank you :)

OTOH, there is an emitter and absorber atom for each photon out there, and it does propagate in real time...

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