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The Mindless Quantum
Why some self-help gurus are off the planet

Adapted from Victor J Stenger, The Mindless Quantum, Skeptical Briefs November 2007 page 7. He is professor of physics and astronomy at the University of Colorado. He is the author of many works including Physics and Psychics: The search for a world beyond the senses (Prometheus Books 1990), which critically examines theories of paranormal realities in terms of all that is currently known in physics, especially quantum physics. His website is at www.colorado.edu/philosophy/vstenger.

Quantum weirdness
In 1800 the British physicist Thomas Young (1773-1829) passed light on to a wall through two narrow slits in an opaque screen. The result was something never seen before -- alternating bands of light and dark on the wall. Young concluded that the bands were caused by interference between light waves coming from each slit. His simple experiment had established the wave theory of light and the principle of interference. It was a milestone in the history of science. (Young had many talents, for example he helped to decipher the Rosetta Stone, was the first to describe astigmatism, and was the originator of Young's modulus, which describes how a solid behaves under stress.)

Waves interfering. Light falls on a screen with two slits, which then act as the source of two new waves. The crests of these new waves (yellow and blue) then make bigger crests (red) where they meet the other's crests, or cancel out where they meet the other's troughs. On the wall they appear as alternating bands of light and dark. The experiment does not work unless the light is of one colour and the slit widths are similar to the wavelength, or less than 0.001 mm.

Later, in the early twentieth century, it was discovered that light also behaved as if it were composed of particles called photons. So it behaved both as a wave and as particles. And it wasn't alone -- all particles of atomic dimensions such as electrons also exhibited the interference shown by waves. So light and electrons were simultaneously waves and particles. It seemed weird, but as we shall see there is a simple explanation.

Enter the mind
How does the mind come into all this? Well, it seems at first that whether something is a wave or a particle depends on what you decide to measure. If you measure a wave property such as interference, it behaves as a wave. If you decide to measure a particle property such as position, it behaves as a particle.

Furthermore, we get the same result even if our decision about what to measure is made a long time after the light has left its source, as with light from a galaxy millions of light years away. The same light is either particles or waves depending on our decision. Some people claim this means our mind not only controls the reality of whether something is a particle or a wave, but also does so over vast distances and millions of years back in time.

At least, that's what the self-help gurus are claiming. But their claim is easily shown to be false. It works like this:

Explaining wave-particle duality
We can set up a double-slit experiment in which the wall behind the slits contains an array of photon detectors sensitive to individual photons. This was not possible before modern technology (an individual photon is an incredibly tiny amount of light), so we are doing something really new. At the start of our experiment we get individual hits just as expected for particles. But as we accumulate data, a fascinating thing happens. The pattern of hits takes the shape of the interference pattern first observed by Thomas Young in 1800!

So, the photon is a particle, and the wave is just the statistical distribution of multiple photons. Which is why particles can behave like waves, and vice versa. In quantum mechanics this wave is called for historical reasons the "wave function", which is somewhat misleading because the wave function merely indicates the probability of finding a particle in a particular location.

Collapsing the wave function
Suppose we start out not knowing where the particle is. This means the particle's wave function is effectively spread out through all possible locations, so the particle could be anywhere in the universe. But when the particle is registered by the photon detector, we know the particle is at the detector. That is, the wave function is now localized at the detector rather than spread throughout the universe. When this happens physicists say that the wave function has "collapsed" as the result of the measurement.

Einstein called this "spooky action at a distance" because in effect the collapse happens instantaneously and everywhere. It seems as if our decision to make a measurement has reached out in space at infinite speed to wherever the wave function could exist including the farthest corner of the universe. What could be more spooky? This is why some people claim that our mind not only controls the reality of whether something is a particle or a wave, but also does so over vast distances and millions of years back in time.

But there is nothing spooky about it. It just seems spooky because of the way we described it as an instantaneous collapse, and because our ignorance of where the particle might be leaves us no option -- we are obliged to see it as being "anywhere in the universe". Of course we could be more reasonable and see it as being "somewhere in this room", even though this immediately destroys our vision of control over vast distances and timescales. But this would be to claim knowledge about the particle's position that we cannot possess. In a sense the spookiness arises only because we are being meticulous about our ignorance.

Strutting the light fantastic
To see why there is nothing spooky going on, look at it this way: Suppose you live on a planet in Alpha Centauri four light years away. Back on Earth, a friend enters your name in a lottery where the prize is one million dollars and your chance of winning is 0.00001%. If you happen to win the lottery, your probability of winning collapses instantaneously to 100%, and your wealth increases instantaneously by a million dollars. But it takes four years for the news, travelling at the speed of light, to reach you and your Centauri bank. The collapse may have been instantaneous but you can't start spending the money until the news arrives. That's how it is in quantum physics.

In short, the collapse of the wave function is just an abstract mathematical device. Even though it happens instantaneously and therefore faster than the speed of light, no actual signal or other practical result can travel faster than light, so this abstract collapse is of no practical value. The self-help gurus are deluded. Nothing in quantum mechanics requires that our minds be able to control reality across great distances and back in time as part of some cosmic consciousness. As the science fiction author Philip K Dick put it, "Reality is that which, when you stop believing in it, doesn't go away."

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