Shaky Foundation
For a century, the edifice of modern quantum theory has stood on an incomplete and specious philosophical foundation. It predicts everything yet explains nothing. The theory’s quandaries arise in two situations: when human observers are absent (the “ontological problem”) and when human observers are present (the “epistemological problem,” or “measurement problem”). The ontological problem refers to the theory’s failure to provide an account of unobserved reality. The measurement problem refers to its failure to account for the process of observation. Both problems are traced to the intrinsic and irreducible role standard quantum theory assigns to human consciousness.
The well-known paradox of “Schrödinger’s cat” illustrates the ontological and epistemological conundrums. The Copenhagen interpretation holds that until observed, a physical entity, rather than in a specific state, is in a superposition of all its available quantum states. Then, at the instant of observation, this mixed state randomly collapses into a single definite state. This is called “collapse of the wave function,” referring to Erwin Schrödinger’s trailblazing wave function describing the possible states and the probabilities of observing each one.
The dead and alive cat prior to opening the chamber illustrates the ontological problem: the lack of a coherent description of unobserved reality. The instantaneous condensation of a dead or alive cat when the chamber is opened illustrates the measurement problem: the conscious observer collapsing the wave function is a deus ex machina standing outside the quantum framework itself. These foundational shortcomings leave adherents of philosophical realism—the commonsense idea that an objective universe exists independent of us—skeptical of the dominant interpretation of quantum theory.
Now, imagine that a cat is sealed in a steel chamber along with a vial of poison and a radioactive substance rigged so that when the substance decays, it releases the poison, thereby killing the cat. Before we open the chamber, according to the standard interpretation, the system is in a superposition of possible states. Since the radioactive substance is in a mixed state of decay and not decay, the cat is also in a mixed state—both dead and alive. But when an observer opens the chamber, she collapses the mixed state into a definite state, a cat that is either dead or alive.