Roy Crawford Smith

Does the delayed-choice quantum eraser experiment imply that conscious awareness collapses the quantum wave function?

Wikipedia has this to say about the delayed choice quantum eraser experiment:

"A delayed choice quantum eraser experiment, first performed by Yoon-Ho Kim, R. Yu, S.P. Kulik, Y.H. Shih and Marlan O. Scully,[1] and reported in early 1999, is an elaboration on the quantum eraser experiment that incorporates concepts considered in Wheeler's delayed choice experiment. The experiment was designed to investigate peculiar consequences of the well-known double slit experiment in quantum mechanics as well as the consequences of quantum entanglement.

Delayed choice quantum eraser

The experiment supports the observer effect in quantum measurements.  The Wikipedia has this to say about the observer effect in the delayed choice quantum eraser experiment:

"Further studies have shown that even observing the results after the experiment leads to collapsing the wave function and loading a back-history as shown by delayed choice quantum eraser.[6]"

Observer effect (physics)

Basically, what causes the collapse is knowledge.  And knowledge requires a knower. 

"The observer plays a key role in deciding the outcome of the quantum measurments - the answers, and the nature of reality, depend, in part on the questions asked." [1]

John Archibald Wheeler said: "It begins to look as if we ourselves, by a last minute decision, have an influence on what a photon will do when it has already accomplished most of its doing...we have to say that we ourselves have an undeniable part in shaping what we have always called the past. The past is not really the past until it has been registered. Or put it another way, the past has no meaning or existence unless it exists as a record in the present." [2]

A conscious choice affects the behavior of previously measured, but unobserved particles.

Physicist Asher Peres, who elaborated the experimental results with his delayed choice for entanglement swapping, says:

"If we attempt to attribute an objective meaning to the quantum state of a single system, curious paradoxes appear: quantum effects mimic not only instantaneous action-at-a-distance but also, as seen here, influence future actions on past events, even after these events have been irrevocably recorded." [3]

Our choice affects how the particle acted in the past.  The factor of time has nothing to do with quantum mechanincs.  This was predicted by quantum mechanics and the exact same result is what we see when we put it to experimental test.

Denial in the Physicist Community

Many physicists try to deny these findings or give alternate readings of the results.  Physicist Henry Stapp rightly points out physicists deny this philosophical conclusion because of  "metaphysical prejudice"

" must ask whether it is really beneficial for scientists to renounce for all time the aim of trying to understand the world in which we live, in order to maintain a metaphysical prejudice that arose from a theory..." (classical Newtonian mechanics and materialism) "---that is known to be fundamentally incorrect?" [4] 

The fundamental role of the observer is even harder to deny with the experimental confirmation of the Kochen-Specker theorem in 2011.
The Kochen-Specker (KS) theorem states that "the non-contextual theories (NCT) are incompatible with quantum mechanics. Non-contextuality means that the value for an observable predicted by such a theory does not depend on the experimental context..."  [5]

So when we are performing experiments, we are not just passively observing how nature progresses, but are actively affecting what the outcome will be by how we observe things.

"The values you obtain when you measure its properties depend on the context.  So the value of property A, say, depends on whether you chose to measure it with property B, or with property C.  In other words, there is no reality independent of the choice of measurement." [6]

"Quantum theory denies the existence of a physically real world independent of its observation." [7]

The measurement problem is only a problem if one cannot accept that the observer plays a fundamental role in shaping physical reality.  We are not passively observing the world, but actively involved.

[1] Paul Davies and John Gribbin, The Matter Myth.
[2] Davies and Brown, The Ghost in the Atom: A Discussion of the Mysteries of Quantum Physics
[3] Asher Peres, Delayed choice for entanglement swapping. J. Mod. Opt. 47, 139-143 (2000).
[4] Henry Stapp, Quantum Theory and the Role of Mind in Nature
[5] A feasible "Kochen-Specker" experiment with single particles
New Scientist | Science news and science articles from New Scientist: Quantum magic trick shows reality is what you make it. 6/22/2011.
[7] Bruce Rosenblum and Fred Kuttner, Quantum Enigma


[quant-ph/0610241] Experimental realization of Wheeler's delayed-choice GedankenExperiment
[quant-ph/0610241] Experimental realization of Wheeler's delayed-choice GedankenExperiment
[1203.4834] Experimental delayed-choice entanglement swapping
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