Quantum mechanics and observation I have read several times by different supposedly knowledgeable authors that conscious observation affects quantum experiments.  
I think these authors are confused, by which I mean they forget that "observing" is not passive.  
To take the double slit experiment for example, observing means that there is at least one photon (used for measuring) interacting with the photon(s) passing thru the slit(s).  
My understanding is that this interaction between the photons traveling thru the slits and the photons used for measuring cause the change in the experiment,  ie. whether someone is there "observing" the experiment is irrelevant.
Is my understanding correct?
 A: Yes, your understanding is correct. Someone who is conscious and/or usefully using the result of the measurement isn't necessary for the experiment to be modified; it's the particles used to detect the slit or other information that modify the experiment. They interact with the photon in the slits etc. (although it's hardly other photons because photon-photon interactions are virtually unmeasurably weak). Quantum mechanics implies that the experiment is modified regardless of any consciousness that is really not a part of physics.
However, the existence of a conscious observer who learns the value of an observable is a sufficient condition for the experiment to be altered. Without an alteration of the experiment, one could never be "aware" of the slit through which the photon went, for example. So the conscious realization of an outcome is a possible proof – one of the possible proofs – that some particles or objects measuring the physical system (double slit experiment, for example) have modified it. That's an "indirect proof" in some sense – one may always say that the actual "constructive" proof involved the actual particles/apparatuses that were used to measure the "which slit" information or any other observable.
