Sunday, May 17, 2020

Does Consciousness Create Reality?

Mandrake the Magician

When David Kaiser charted the history of a small group of independent scholars exploring the foundations of quantum mechanics outside the usual channels (How the Hippies Saved Physics, 2011) he said not a word about the AMY Project which focused on a particular physics experiment that looked like it might be able to answer the important question: "Does consciousness create reality?"

Erwin Schrödinger started it all with his famous cat in a box. Unlike the classical objects of everyday life, a quantum object can exist in a superposition of states, can be,  for instance, in two places at once. Schrödinger assumed that quantum mechanics applies to everything, not just the very small, and devised a clever thought experiment in which a cat-in-a-box is both alive and dead at the same time until someone opens the box and looks. Observation destroys the superposition and the experimenter will see either a dead cat or a live cat.

Schrödinger's thought experiment which is totally impractical to carry out, is suggestive of the notion that consciousness might act on the quantum level to bring reality into existence.

Recently in 1976, a pair of physicists from Durban, South Africa, Donald Bedford and Derek Wang, proposed a practical experiment they called An Interfering Schrödinger Cat (D. Bedford and D. Wang, Il Nuovo Cimento 32B, 243 (1976))

Bedford and Wang's experiment is a simple variation on the familiar double-slit experiment, in which a beam of light goes through two slits at once and creates an interference pattern of alternating dark and light regions on a screen behind the slit.

Instead of a single pair of slits, Bedford and Wang introduce a two-component superposition of single slits that modulate the light beam. Small objects like atoms are easy to superimpose; whether large objects like metal plates with holes in them can be made to coexist in a Schrödinger Cat-like state is problematic. For this reason any macroscopic superposition whether theoretical or actual has come to be known as a "cat state". When the objects being superposed are tiny, one sometimes hears physicists describe such situations as "kitten states"

Two Experiments: 1. Double Slit and 2. Two-Slit Superposition

One way of looking at the Bedford and Wang proposal is that as long as the superposition of two slits is not looked at, the light will go through both slits and form an interference pattern. However if someone looks at the slits, the superposition will collapse into a mixture of single slits and the interference will vanish. Thus, on the face of it, this experiment looks as though it might be able to test the conjecture that observation changes reality. The Bedford and Wang experiment seems to offer the potential to demonstrate a concrete difference between the world unlooked at and the world observed.

The notion that mind creates reality has a long history, most famously exemplified by the Irishman  George Berkeley (1685 - 1753), Bishop of Cloyne in County Cork, whom his fellow countryman, William Butler Yeats, eulogized thus:

And God-appointed 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.

More recently, this idealist philosophy (the world is not made of things but of ideas) has been championed by the Dutchman Bernardo Kastrup, expressed in such books as The Idea of the World and Why Materialism is Baloney.

The belief that matter can exist on its own without reference to mind might be called "independent material existence." The opposite belief is then "anti-independent material existence" abbreviated AIME which we shortened to AMY. The aim of our AMY Project was to examine the exciting possibility that there might exist a physics experiment that could refute the materialist hypothesis and perhaps establish the truth of Bishop Berkeley's exhortation:

All the choir of heaven and furniture of earth
in a word, all those bodies which compose the frame of the world
have not any substance without a mind.

The AMY Project involved about a dozen people, including myself and Saul-Paul Sirag, as well as philosopher Abner Shimony, physicists Bruce Rosenblum, Henry Stapp, John Cramer, Casey Blood, Beverly Rubik, Evan Harris Walker plus Erwin Schrödinger's last graduate student in Dublin, Ludvik Bass. At the invitation of physicist Amit Goswami, back in 1991, Nick Herbert spent two days at the University of Oregon in Eugene presenting the original B&W experiment and some of its variations.

In their original paper, Bedford and Wang argued that the superposed slits would cause no interference whether observed or not. This conclusion was independently verified by the calculations of Casey Blood at Rutgers University in Camden, NJ. In retrospect one can now recognize that the two light paths and the two superposed slits are quantum-entangled (unlike the simple double-slit experiment) and it is easy to show that entangled particles do not show interference effects.

So, in the B&W experiment, there is no interference on the screen before looking. And no interference after looking. Nothing happens when someone looks at the superposed slits.

So all that excitement was for nothing. The Amy Project failed in the sense that the B&W experiment does not test the idealist hypothesis. But there do exist quantum experiments where looked at and unlooked at systems gave different results, such as those cited by Bruce Rosenblum & Fred Kuttner in their Quantum Enigma: Physics Encounters Consciousness. However, despite these authors' contentions, such experiments do not reveal a hidden power of mind.

Why not? Because "looked at" in physics means deploying some sort of physical instrument. Just paying attention is not enough. The action of mind in physics experiments is simply to select which machine to deploy to ask nature a particular question. Different questions require different machines. So, in my opinion, consciousness, even in quantum physics, seems to play the same indirect role in creating reality as choosing which gear to put your car in when climbing a hill.

Bedford and Wang not only proposed a theory, they actually carried out an experiment. However there is some doubt whether B&W were actually able to superpose two macroscopic slits. Recently an elegant experiment by Kim et al has succeeded in achieving exactly the B&W configuration using the resources of modern optics. All sorts of variations that Bedford and Wang never dreamed of can now be carried out on this sophisticated platform. Needless to say, none of these experiments can be used to support or refute the idealist hypothesis. All is not lost, however. There are other paths to reality besides quantum physics.

OK, we were wrong. But can you imagine how exciting it felt to believe for a while that you were working on an actual physics experiment that might prove this world is a dream?


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Stas said...

I wonder why can't one create interference fringes if the slit-lightbeam system is in an entangled state by observation of the slits.
If the slit-lightbeam state is for example |SlitR>|LightR>+|SlitL>|LightL> (with L&R being left and right holes and respective paths), then by observing slits in SlitR vs SlitL basis leaves the light in LightR vs LightL state respectively and then there's no interference. But if one observes slits in (without normalization) SlitR+SlitL vs SlitR-SlitL basis - the light is left in a superpositional state of LightR+LightL vs LightR-LightL dependent on the observation of the slits. Such observation would result in interference fringes on the screen.
The problem is that each new photon going through superposed slits would create entangled state with them. So if we imagine photons going one-by-one, our measurements of slits would result in different state (|SlitR+SlitL> or |SlitR-SlitL>) for different photons with 50% probability for each, as a result the state of the photon would correspond either to one superposition or to another and when we would look at the cumulitive pattern on the screen there would be no intereference. However, if we would run experiments one-by one, recording the results of slit measurement and results of where the photon fell on the screen and then drew a pattern of only those photons that fell on the screen when the measurement of slits was |SlitR-SlitL>, there would be interference pattern on the screen. Also with the other half of photons.
Like quantum eraser, but other way around
Isnt it so?