Two recent film documentaries echo the message of self-help gurus, like Deepak Chopra, that we can change our lives, heal all our ills, and become rich and famous just by thinking we can do so. They assert that quantum mechanics enables us to alter reality with our thoughts alone. “The physical world is a creation of the observer,” Chopra declared in his 1993 bestseller Ageless Body, Timeless Mind: The Quantum Alternative to Growing Old. In What the Bleep Do We Know!? (2004), Amanda, a deaf photographer played by Marlee Matlin, finds an Alice in Wonderland world of quantum uncertainty hidden behind familiar reality and learns that the universe is constructed from thoughts, not matter. In The Secret (2006), an ancient “hidden secret” for worldly success is revealed: you can do whatever you want, be whoever you want to be, and have wealth and power, just by thinking about it. All these powers of thought are granted by quantum mechanics.
What we see here is simply the reappearance of the ancient philosophical doctrine of idealism, this time arising from misinterpretations of certain quantum phenomena that strike many people as weird because they are not part of everyday experience.
In 1800, Thomas Young passed light through two narrow slits in an otherwise opaque screen. He observed alternating bright and dark bands of light on the surface illuminated by the light from the slits. This was interpreted as the pattern of interference between light waves emerging from each slit. Since then, science has treated light as a wave phenomenon.
In the early twentieth century, it was discovered that light also seems to be composed of localized particles called photons. In addition, objects such as electrons, which we normally think of as particles, also were seen to exhibit the interference behavior associated with waves.
Where does the mind come into all this? Well, it seems at first glance that whether an object is a wave or a particle depends on what you decide to measure. If you measure a wave property such as interference, then the object is a wave. If you decide to measure a particle property such as position, then the object is a particle.
For example, suppose in the double-slit experiment that we put a photon detector behind one slit. If the detector is on, then we know which slit the photon passed through and we get the two bright bands on the wall expected for a localized photon passing through either slit. In this case, the light is particle-like. If the detector is off, we get the interference pattern, and the light is wavelike.
Furthermore, we can set up the experiment so that the decision to measure a wave property or particle property is made after the object leaves the source. That source can be light from a galaxy thirteen billion light-years away. Some take this to mean that the mind not only can control the reality of whether an object is a particle or a wave, but it can do this over a distance equal to the size of the visible universe and thirteen billion years back in time.
At least, that’s the snake oil that Chopra and the Bleep and Secret crews are trying to sell us. In fact, it is easily shown to be bogus. We can set up a double-slit experiment in which the surface illuminated by the light from the slits contains an array of photon detectors sensitive at the one-photon level. Even with the slit detector off, we get individual, localized hits just as expected for particles. But as you accumulate data, a fascinating thing happens. The pattern of hits takes the shape of the same diffraction pattern first observed by Thomas Young in 1800!
So, the photon is not the wave; the wave is the statistical distribution of multiple photons. In quantum mechanics this wave is called the “wave function,” a mathematical tool used to compute the probability for finding a particle at a particular position.
Suppose we start out not knowing the position of a particle. Then the particle’s wave function is in some sense spread throughout the universe. It has the same magnitude at every spatial point. Then when a measurement is made, the particle’s position is found to be in some small region the size of the detector, and the wave function is therefore localized. Physicists say that the wave function has “collapsed” as the result of the measurement. Einstein called this a “spooky action at a distance,” since the collapse happens instantaneously throughout the universe. Again, it would seem that the act of conscious measurement has reached out in space at infinite speed to the farthest corner of the universe.
But there is nothing spooky about it. Suppose you are a resident of a planet in Alpha Centauri. Back on Earth, a friend enters your name in a lottery in which your chance of winning the prize of a million dollars is one in a million. If you win the lottery, your probability of winning collapses instantaneously to unity, and your wealth increases instantaneously by a million dollars. But it takes four years for the news, traveling at the speed of light, to reach you and your Centauri bank. You can’t start spending the money until that happens. That’s how it is in quantum physics. The collapse of the abstract wave function is just a mathematical artifice. Even though this happens at faster than the speed of light, any signal and other practical result will be limited by relativity and the laws of conventional physics.
In short, nothing in quantum mechanics requires that our minds be able to act across great distances and back in time to control reality as part of some cosmic consciousness. As Philip K. Dick put it, “Reality is that which, when you stop believing in it, doesn’t go away.”