Likeness, not physics

The teaching

As the quantum theory of the physics textbooks teaches it.

What a quantum is

Max Planck found that energy is given off and taken in not as a smooth flow but in packets, each carrying an amount fixed by its frequency, and Einstein showed that light itself arrives in such packets. A quantum is one of these smallest amounts. An electron in an atom can hold only certain energies and jumps between them, giving off or taking in a quantum of light. A quantum leap is therefore the smallest change nature allows, the opposite of what the phrase has come to mean.

The wave function and its odds

Quantum theory describes a system by a wave function, a mathematical object that gives each possible result of a measurement a number called an amplitude. The square of an amplitude's size is the probability of that result; this is the Born rule. Before measurement the system is in a superposition, a combination of possibilities whose amplitudes can add or cancel like waves, and that adding and cancelling is what makes the bands of light and dark in the double-slit experiment. The amplitudes are fixed by the physical set-up and change according to an exact equation, Schrödinger's. Nothing in the theory lets a person choose which result appears in a single measurement: only the odds are fixed, and the apparatus fixes them.

The field of all possibilities

A popular teaching, associated today with Joe Dispenza among many others, speaks of the quantum field as a field of infinite possibilities from which a person draws their future. By clear intention joined to elevated emotion, it holds, one collapses a chosen possibility out of the field and into one's life, as the observer in physics collapses the wave function.

The physics beside it is this. A quantum field in physics is the field of a particular kind of particle, the electron field or the field of light, and its possibilities are the possible states of those particles, with odds fixed by the equations. No experiment has let an observer select an outcome; random number generators built on quantum events are trusted for the very reason that no one can steer them. The picture of choosing from a field of possibilities is a likeness drawn from the physics, and it can be kept as a likeness, not as a mechanism.

The observer

The most borrowed idea of all is the observer effect, taught as the discovery that reality does not exist until a conscious mind looks at it, so that attention shapes the world.

In physics an observer is anything that records which of the possibilities happened. In the double-slit experiment the bands vanish when a detector at the slits marks which opening each particle passed through, whether or not any person ever reads what it marked; and in the experiments called quantum erasers, the bands can be recovered when the record of the path is erased. What matters is whether the information exists somewhere in the world, not whether a mind holds it. A measurement is a physical interaction, and a stray molecule of air can make one.

What happens at a measurement

Why one result appears out of many is called the measurement problem, and physics offers several answers. In the Copenhagen account the wave function is a tool for predicting results, and it gives way to a definite result when a measurement is made. In the many-worlds account nothing collapses: every result happens, each in its own branch of an ever-dividing universe. In pilot-wave theory, David Bohm's among others, particles always have definite positions and are guided by the wave. Collapse theories add a small, spontaneous collapse to the equations. A few have proposed that consciousness completes the measurement; it is a minority view, and the standard accounts need no mind.

Decoherence

A system stays in superposition only while it is isolated. As soon as it interacts with its surroundings, a molecule of air, a particle of light, the warmth of a wall, the delicate relation between its possibilities spreads out into the surroundings and is lost for every practical purpose. This is decoherence, and it is why chairs and cats are never seen in two states at once. In a warm, wet brain it happens in far less than a millionth of a millionth of a second, much faster than nerve cells act. The one serious proposal that consciousness rests on quantum effects inside nerve cells, the microtubule theory of Roger Penrose and Stuart Hameroff, must show how its quantum states survive that warmth, and this is the objection it meets.

Entanglement

Two particles prepared together can share a single joint state, so that neither has a definite property of its own until it is measured, yet their results, when compared, match in a way that no instructions carried from the start could produce. John Bell showed how to test this, and the tests have confirmed it again and again. But the results on each side, taken alone, look perfectly random; the match appears only when the two lists are brought together by ordinary means, a call or a letter. No message, no energy and no feeling passes between the particles, and the link is broken by the first stray interaction with anything else.

The bond across distance

On this physics a large teaching has been built: that all of us are entangled, that people who love each other stay linked by quantum bonds across any distance, and that a prayer or an intention travels instantly to its object.

Entanglement belongs to particles prepared together and kept apart from everything else. A human body is a crowd of particles meeting their surroundings countless times a second, and any entanglement among them is lost at once; and even where entanglement exists, it carries nothing. The bond between people who love each other is real. It is carried by memory, by letters and calls, and by what each knows of the other, and it does not need physics to be true.

Uncertainty

Heisenberg's uncertainty principle says that certain pairs of quantities, such as the position and the momentum of a particle, cannot both be sharply defined at once: the more exactly one is fixed, the less exactly the other can be. It is a precise limit, set by Planck's constant, and for anything as large as a grain of sand it is far too small ever to notice. It is sometimes taught as meaning that nothing is certain and so anything is possible. It means the reverse: it states exactly what cannot be known together.

The vacuum and the Field

Some teachers, Lynne McTaggart in The Field among them, describe the zero-point field as a sea of energy and information beneath everything, linking all minds, which might be tapped for healing and for free energy.

In quantum field theory even empty space has a lowest possible energy, the zero-point energy, and its fluctuations are real: they produce a tiny measured force between metal plates set a few millionths of a metre apart, the Casimir effect. But the lowest state is by definition the bottom. No energy can be drawn out of it to run anything, as water lying at the bottom of a valley cannot be made to turn a wheel, and it holds no record of people.

Quantum healing

Deepak Chopra's Quantum Healing teaches that the body is at bottom a field of intelligence and information, and that a shift of awareness at this quantum level can change the body itself.

The body does run on quantum mechanics, as all chemistry does: the bonds that hold its molecules together, the working of its enzymes, the way the eye catches light, and in some reactions particles tunnelling through barriers they could not cross by the older rules. Quantum biology studies such effects in photosynthesis, and perhaps in the way birds sense the Earth's magnetism. These are the quantum mechanics of electrons in molecules, measured in laboratories of chemistry; they are not a channel through which thought acts on the body.