Imagine you tossed a coin into the air, and as the coin was in mid-flight, somebody said to you that it would land both heads and tails at the same time. You would doubt their sanity. But if that person were a quantum physicist, you might give them more credibility. And they, for their part, would simply be telling you what the quantum theory—one of the most successful theories in the history of science—states. Still you have your doubts, and when the coin lands on the ground and you look at it, you find, to your great relief, that the coin is either heads or tails; it is not both. Your physicist friend, however, tenaciously holds on to his statement. Interestingly enough, you are both right.
–Dean Radin (Senior Scientist at the Institute of Noetic Sciences (IONS), in Petaluma, California)
In the weird and wonderful world of quantum physics, we cannot predict with certainty what the outcome of an experiment will be. Try as we might, we just cannot calculate an answer because the theory cannot provide it. At best it can give the probabilities of each of the possible outcomes— in the case of our coin toss, a 50% likelihood of heads and 50% for tails—but it cannot predict with certainty which outcome will prevail when a measurement is actually made. Thus, according to quantum theory, until we have looked at the coin on the ground, its state is some curious, counter-intuitive mixture of half-heads and half-tails. Then, when we look at it, voila—either heads or tails appears. It is in that ‘voila’ moment that we encounter a conundrum of quantum physics, the problem of measurement. This irksome question has provoked much discussion and debate, as least on a philosophical, if not on a practical level, since the inception of quantum physics.
The mysterious combination of two states—heads plus tails—is technically called superposition in physics. In this case we have what we could call a ‘heads plus tails’ state. A quantum measurement could involve the energy levels of an electron in an atom, the spin a photon, or any of a myriad of other things. The main point is that the theory alone cannot give the answer. This is not a defect in the theory; it’s simply as far as it goes.
The renowned quantum physicist Ervin Schrödinger illustrated this state of affairs rather poignantly when he proposed his famous cat paradox. Suppose, he said, you placed a cat in an enclosed box along with a radioactive substance that had a 50% chance of decaying in a time period of one hour. If the substance decays, then a vial of poisonous gas is released into the box, killing the cat. After an hour an experimenter opens the box and looks inside. According to quantum theory, before the box is opened, the condition of the cat is a blurred ‘half-dead-plus-half-alive’ state. When the experimenter does indeed observe the cat, common sense prevails and it is either living or deceased, but not both at the same time.
What is happening here? What is it that intercedes in these experiments to make the coin either heads or tails, or the cat either living or dead when the theory cannot tell us which will be the case? It appears that something is missing. Some element is needed to ‘collapse’—to use the scientific word—all of the possible theoretical outcomes into the one which actualizes when the experiment is performed in the real world. This something would decide whether the coin is either heads or tails, or that the cat (1) is either dead or alive, but not both. This question is at the heart of the quantum measurement problem.
In the late 1920s, the physicist and mathematician John von Neumann proposed a solution to this conundrum. He reasoned that the interceding element must be something which is not subject to the laws of quantum physics. Since these laws apply to all of the matter and the time and space of the universe, we must be looking for something which is beyond the material. The key, von Neumann proposed, is the consciousness of the human observer—the one who looks at the coin or inside the box. Consciousness is not subject to the strictures of quantum rule because it is neither physical matter, nor is it restricted by time and space. The human observer, endowed with awareness, is a vital component in a quantum experiment and must not be ignored. Until a human being observes the system being measured, it remains the blurred quantum mixture of all the possible outcomes. When a conscious observation is made, all of these potential results collapse into the one that actualizes. Physics, the science which deals with the material world, had happened upon the non-material world of consciousness and had provided the link between these seemingly disparate realms.
(1) Author’s note : I’ve always thought it a little insensitive to pose a situation in which the cat should be killed. Even Schrödinger himself begged his readers to ‘pardon the expression’ of a ‘dead cat.’ Perhaps a vial of sleeping gas would have provided a gentler example.
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