Quantum Reality, by Nick Herbert, is an excellent discussion of what quantum mechanics has to say about the nature of reality. It turns out that physicists don't agree on the nature of reality. Dr. Herbert describes eight different possible quantum realities:
QR #1: The Copenhagen Interpretation, Part I - There is no deep reality. As Niels Bohr put it: "There is no quantum world. There is only an abstract quantum description." (p. 17)
QR #2: The Copenhagen Interpretation, Part II - Reality is created by observation. As John Wheeler put it: "No elementary phenomenon is a real phenomenon unless it is an observed phenomenon." (p. 18)
QR #3: Reality is an undivided wholeness. As David Bohm put it: "One is led to a new notion of unbroken wholeness which denies the classical analyzability of the world into separately and independently existing parts." (p. 18) In other words, the observer cannot be considered separate and distinct from the object being observed.
QR #4: The many-worlds interpretation - Reality consists of a steadily increasing number of parallel universes. Proposed by Hugh Everett in 1957: "in the Everett picture, everything that can happen does happen." (p. 175) Sounds like Douglas Adams.
QR #5: Quantum logic - The world obeys a non-human kind of reasoning. As David Finkelstein put it: "Our classical ideas of logic [based on the ideas of Aristotle and Boole] are simply wrong in a basic practical way. The next step is to learn to think in the right way, to learn to think quantum-logically." (p. 21)
QR #6: Neorealism - The world is made of ordinary objects, that is, objects which possess attributes of their own whether they are observed or not. This was Einstein's view.
QR #7: Consciousness creates reality. This is a stronger version of QR #2. John von Neumann helped create this view. As his colleague Eugene Wigner put it: "It is not possible to formulate the laws of quantum mechanics in a fully consistent way without reference to the consciousness." (p. 25)
QR #8: The duplex world of Werner Heisenberg - The world is twofold, consisting of potentials and actualities. In the quantum world there exist only potentials, which become actualities in the real world during the "magic act of measurement."
The Copenhagen Interpretation is the dominant view in physics today. But all of these interpretations have credible proponents. Dr. Herbert says that all of these interpretations are consistent with all known experiments. Are they perhaps therefore somehow equivalent?
For more on Bohr, Heisenberg and the Copenhagen Interpretation, see my series of posts in 2008 about the play Copenhagen.
Let's consider what this means for humans. Are humans special? The "no" position is eloquently stated by Douglas Adams. The "yes" position is just as eloquently stated by Jaron Lanier and Herman Wouk.
I think most physicists—including Einstein, Bohr, Heisenberg and Feynman—would agree with Adams. But not so fast. Doesn't QR #7 imply that humans are special? And see Copenhagen, part 4 where Niels Bohr says (in the playwright's words): "We put man back at the centre of the universe."
So, are humans special or not?
Dang. Stumped again. I'm sure the answer is right here in something that I've posted about, but it's just not coming to me. Maybe if I sleep on it the answer will come to me tomorrow.
UPDATE: I've got it!