In my book "Quantum Reality" I described eight conceivable interpretations of quantum theory--eight different quantum realities compatible with the quantum facts. Quantum Reality #7 (originated by Hungarian polymath John von Neuman) imagines that CONSCIOUSNESS acting outside of material reality causes quantum possibilities to actualize as observable events. Like the other seven realities, the von Neuman consciousness-based reality was long thought to be untestable since, like the others, it seems to predict exactly the same quantum facts.

However a curious paper by a pair of physicists from South Africa, Bedford & Wang, proposed an experiment (which they called "an interfering Schroedinger Cat") which B & D claimed would give different results depending on whether mind was necessary to "collapse the wave function" or not.

Suppose a photon strikes a half-silvered mirror. Quantum theory obliges us to believe that, until it is actually observed, we must imagine that the photon takes both paths. Depending on what we imagine an "observation" to be, the reality of this split-photon experiment can get quite bizarre. Suppose we place one photon detector in path A and one in path B. In the absence of human observation we may imagine (without violating quantum rules) that both counters are triggered. And we are free to imagine (as did Erwin Schroedinger in 1935) that detector A operates a mechanism to feed a cat while detector B operates a mechanism to kill the same cat. Thus in the absence of human observation, quantum mechanics seems to predict the existence of a cat that is both alive and dead at the same time. When a human looks however, his act certainly counts as an "observation" so he sees only one cat, either alive or dead, but never both. For more than half a century, the existential status of Schrodinger's famous unobserved cat has been argued in physics labs all over the world with no definite conclusion.

Bedford & Wang say, forget about cats. Let detector A open an aperture A and detector B open a nearby aperture B. Don't let human beings see the apertures. Shine a light on both apertures and focus the light that gets thru onto a screen. Let a human being (HB) observe only the screen.

Then, B & W argue, if human consciousness is necessary to "collapse the wavefunction" (Reality One), both (humanly unobserved) holes will be open at once and HB will see a double-slit interference pattern; if the wavefunction of the apertures collapses without human intervention (Reality Two) we should see a one-slit pattern. More accurately, since this experiment must be repeated to make sense (a single photon is not a pattern), HB will see (if Reality Two is correct) an incoherent mixture of light from aperture A and aperture B.

B &W claim, in short, that a mind-caused world (Reality One) leads to a double-slit pattern; a purely material world (Reality Two) leads to sum of two single-slit patterns.

The most interesting feature of the B & W experiment is that it claims to be able to distinguish by purely physical means between a mind-created world and one that is purely material. This claim prompted the formation of the AMY group for studying this question in depth. The notion that the world exists even in the absence of mind is called: Independent Material Existence (IME). The opposite claim (often called "Idealism" or Mind-created Reality") is of course Anti-IME or AIME. Which we shortened for euphony to AMY.

The goal of our AMY group is to test BY PURELY PHYSICAL MEANS whether or not this world is mind-created. Our first job was to critically examine Bedford & Wang's proposal.

The founding members of the AMY group were myself, Amit Goswami (author of a book on idealistic physics), Professor Casey Blood at Rutgers/Camden, who believes that Bell's theorem imples an idealist basis for reality and Ludvik Bass from the University of Queensland, Australia, who was Erwin Schroedinger's last graduate student at the University of Dublin.

In a series of AMY newsletters we examined the Bedford & Wang experiment, using density matrices--a more general form of quantum theory than wavefunctions and more appropriate for calculating the effects of entangled subsystems on the final result. We convinced ourselves that the B & W claim was spurious: a simple density-matrix calculation showed that only one aperture is ever open whether mind collapses the photons at the screen or materialism collapses the photons at, say, detector A. However some of us wondered whether the B & W proposal could be modified to actually make the idealist/materialist distinction experimentally possible.

Nick Herbert came up with a modification of the B&W proposal which he called RISC for "really interfering Schroedinger's Cat". Herbert replaced B & W's final viewing screen with a beam splitter which coherently mixes the photons passing thru apertures A and B and outputs the mixed light into two new channels C and D. Then he argued, using density-matrix calculations, that an observation of a single photon in a beam splitter channel, say C, would collapse the apertures A & B into a S-cat superposition after which all subsequent photons would be directed into channel C. If the apertures collapsed on their own (as materialist's would have it) then photons would go into beam splitter channels C & D with equal frequency.

Herbert presented his RISC proposal--a putative purely physical test of the idealist hypothesis--at a packed physics colloquium at the University of Oregon where it was received with great interest and excitement. However a few days before this seminar, Herbert had received a letter from Casey Blood demonstrating that whether the slits were in an S-Cat superposition or were randomly collapsed by some internal material process the observed outcome would be the same--equal numbers of photons in the C and D beam-splitter channels. So at the end of Nick's talk he had to reveal that no matter how exciting this new test of idealism might appear, it had unfortunately been refuted just a few days before. The AMY program, in this case had failed. Despite our best efforts we still lack the experimental means to tell whether the phenomena we see around us are mind-created or would in fact exist if every mind were annihilated.

The motto of the AMY group, by the way, is William Butler Yeats's poetic tribute to fellow Irishman Bishop George Berkeley, one of the West's foremost spokesmen for idealism:

And God-apponted Berkeley that proved all things a dream
That this pragmatical, preposterous pig of a world, its farrow that so solid seem
Must vanish on the instant if the mind but change its theme.