So, is it one mind or many? This is the question that confronted quantum physicists when they tried to come to grips with the implications of quantum theory. In classical physics, the world is presumed to exist independently of an observer, so the issue never comes up. In the quantum world, however, elementary particles exist in an indeterminate state until they are measured, which means you need an act of observation to produce such qualities as mass, location and velocity. Or as the 18th-century Irish cleric Bishop Berkeley put it long before quantum physicists did the math: “To be is to be perceived.” The issue then is whether every observer lives in his own separate world, as Leibniz argued, or, if there is only one world, then how do you explain all those separate minds observing a single reality? For Erwin Schrödinger, one of the originators of quantum theory, the conclusion was inescapable: if we are all living in and observing the same world, then there can only be one mind. In My View of the World, he wrote, “There is no kind of framework within which we can find consciousness in the plural; this is simply something we construct because of the temporal plurality of individuals, but it is a false construction.”
As Schrõdinger himself readily conceded, this conclusion is hardly original with him. He was a student of Advaita Vedanta, a 2,500-year-old Hindu philosophy that also maintains consciousness is singular rather than plural. Advaita is a Sanskrit word that literally means “not two.” Underlying the apparent multiplicity in the world was a single reality that was apprehended by a single mind, which was not separate from the world it beheld but identical with it. Subject and object were one; likewise, our apparently finite individual mind was one with the mind of God.
This view might appear at first to be utter solipsism, if not monstrous self-aggrandizement; in fact, it is quite the opposite. The confusion comes in thinking that my mind is the mind of God. We assume that subject takes possession of object, when in reality they both disappear into a single consciousness that is possessed by no one. And yet there are billions of people in the world, all of them equipped with a brain, all of them thinking their own thoughts, rarely in full agreement on much of anything by the looks of it. How do you solve what Schrödinger refers to the “arithmetic problem,” i.e., how many minds can be part of a single reality? Elementary, my dear Watson. It is a matter of simple deduction. Unless every mind is a world unto itself, there can only be one mind. Or, as Sherlock Holmes himself might say, “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.”