Reality doesn’t disappear just because it’s quantum

BY C.S. MORRISSEY

Einstein famously posed an insightful question for everyone who thinks about the meaning of quantum theory: Does the moon exist only when you look at it?

Quantum theory was developed in the 20th century as a mathematical description of the observed behaviour of the smallest things in nature. Sometimes these smallest things seem to act like waves. Sometimes they act like particles. But how can something be both a particle and a wave?

Different answers to this question have led to the different philosophical interpretations of quantum theory.

The best interpretation, in my opinion, is by the physicist Dr. Anthony Rizzi of the Institute for Advanced Physics. His series of textbooks, Physics for Realists, explains modern physics better than anyone else since he proceeds from the standpoint of the common-sense realism of St. Thomas Aquinas.

Rizzi has even authored two volumes of A Kid’s Introduction to Physics (and Beyond), which show how this natural approach makes physics exciting and accessible to seventh- and eighth-grade students. Bright sixth-grade students can even get an early start with these books.

If you are looking for the best homeschooling resources in this time of the coronavirus pandemic, these are the books for you. Adults will be surprised at how much better they themselves can learn and understand physics from them, especially compared with their own early science education.

The problem with the most common ways of teaching and understanding science is their failure to affirm the realist standpoint. Aquinas and Aristotle are perhaps the greatest philosophical proponents of this realism, but with his question about the moon, Einstein is also a great scientific proponent of realism.

However, today the most popular interpretation of quantum theory among physicists is the “many worlds” interpretation, which posits the actual existence of other universes that correspond to the mathematical descriptions of all possible outcomes for quantum-level events.

This is as crazy as saying that another copy of our universe is created whenever you see that the moon looks different. That may be science fiction, but it is not scientific realism.

Today’s “many worlds” interpretation tries to move beyond what was the most popular interpretation among physicists in the 20th century. Known as “the Copenhagen interpretation,” it was typical of physicists like Werner Heisenberg and Niels Bohr (who famously worked together in the 1920s in Copenhagen).

Put simply, this interpretation says that we can’t know what the real nature of a quantum thing is (for example, if it is a particle or a wave), but we can try to measure it. We can also mathematically describe the possible measurement outcomes. But nothing can be considered real until we measure it.

Now we see why Einstein asked his famous question. Surely the moon, simply because we look at it, does not become real. Rather, because it is already something substantial, we can then look at it and subsequently observe its properties.

The Copenhagen interpretation is a direct refusal to affirm such straightforward realism. When it comes to the unfamiliar quantum world, things of the smallest sort do not behave like the moon. The moon is large, and therefore more predictable in its behaviour.

For the small things described by quantum theory, we have a range of possible outcomes described by the mathematics. The outcomes are indeterminate until we make an actual observation, which then influences the quantum state to manifest an actually observable property.

The Copenhagen interpretation of the mathematics of quantum theory calls this occurrence “state vector collapse.” On this view, observation makes quantum things real by causing a “collapse” of the probability they might be this way or that way.

But as Rizzi explains in detail in his brilliant new textbook, Physics for Realists: Quantum Mechanics, it makes no sense to speak of a “collapse” of the mathematics when we make an observation. We also don’t need to postulate “many worlds” that avoid this nonsensical “collapse” by suddenly making all the mathematical possibilities simultaneously actual.

What we need, rather, is to properly distinguish the physical from the mathematical. The mathematics does not suddenly become real simply because we look at it. It is only a statistical description of “an ensemble of similarly prepared physical systems.”

For too long, interpretations of quantum theory have been “lost in math” (to use Dr. Sabine Hossenfelder’s phrase) and unable to give a satisfying account of the physical reality beneath the mathematics of quantum theory.

Last century, with his innovative definition of angular momentum in general relativity, Rizzi deepened our understanding of Einstein’s theory. Today, he is the realist who is leading the way to deepen our knowledge of the physical reality that lies beneath what quantum theory mathematically describes.

Dr. C.S. Morrissey is a certified member of the Institute for Advanced Physics.