I’m new to physics forums, I have a question regarding the collapsing wave functions and the concept of superposition of states. I am a geologist (with a rather limited education in quantum mechanics) however I have recently become very interested in the concept of collapsing wave functions. The standard interpretation, as I understand it, is that small particles like electrons or photons when emitted exist in a superposition of states that spread out and increase (the number of possible states) as a wave until an observer collapses their position and poof! it becomes a particle again. This interpretation is of course demonstrated by observations of the classic two-slit experiment where and electron's probability wave spreads out through both slits and interferes with itself until the electron hits the detector and is observed to be a particle once again. Personally, this seems to raise some puzzling philosophical questions like "what qualifies as an observer?” In the book(adsbygoogle = window.adsbygoogle || []).push({}); Schrödinger’s Kittensby John Gribbin a rather interesting thought experiment is outlined:

A single electron is contained (hidden) in a box in such a way that its probability of position spreads out uniformly until it encompasses the entire volume of the box. There is a gate that slides down to divide the box in half so that there is an equal probability that the electron exists in either half of the now divided box. Now, each half of the box has a gate which when opened allows the electron to move into a separate respective room containing a kitten. In each room is a detector which when stimulated by a passing electron releases a poisonous gas to kill the kitten. The two kittens, each of whom with their lives now entangled with the probability that the electron exists in one or the other half of the initial box, would seem to hang in a state of superposition (dead or alive) until an observer comes along and opens a room to see which kitten has expired, thus collapsing the wave function.

Or are the kittens intelligent enough to be wave-collapsing observers?

One solution put forth by Gribbin's book comes from the Wheeler-Feynman absorber theory (originally meant to explain resistance in radio transmission) seems to say that the uncertainty of the electrons position is merely an illusion. The electron sent out a sort of pilot-wave (retarded wave) and received a confirmation wave (advanced wave) backward through time. Thus, the electron "knew" which detector it was going to intercept before the experiment began.

Essentially electrons communicating with electrons through time using photons. The implication of this seems to be that a photon cannot be emitted unless it has received a conformation wave from the electron that will absorb it in the future. Strange indeed! But it makes a lot of intuitive sense to me. Does this theory continue to hold up in current interpretations?

Sorry to be so long winded but it felt like there were a lot of pieces to set up such a question.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Oberver Collapsing Wave funcions vs. Wheeler-Feynman Absorber

**Physics Forums | Science Articles, Homework Help, Discussion**