Does reality need realism?
If that seems like a strange question to you, keep in mind the fact that this is extremely pressing for physicists and their most successful theory about the physical world. This theory is called quantum mechanics – and every digital electronic device you've ever used owes its existence to the understanding of physics at the atomic level.
But quantum mechanics, despite its success, has a tiny problem: No, it understands.
To be more specific, nobody really understands, a century after birth, what quantum mechanics tells us about the nature of reality itself. This open and insecure territory is at the heart of Lee Smolin's new book Einstein's unfinished revolution: The search for what is beyond quantum .
Smolin is an extremely creative thinker who has been a leader in theoretical physics for many years. He is also a gifted writer who manages to translate his own insights into the workings of science into an exciting language and captivating stories. I had the pleasure to meet Smolin several times at scientific events and to admire his originality and iconoclasm. Both can be seen in Einstein's unfinished revolution . The fact that I disapprove of him and his attitude to quantum mechanics made my enjoyment of the book even deeper.
Disagreement pretty much defines the debate about the importance of quantum mechanics, and Smolin's book is the latest addition to a stream 19459011 through two doors at once: the elegant experiment that solves the mystery of our quantum reality by Anil Ananthaswamy and What Is Real? The Unfinished Quest for the Meaning of Quantum Physics by Adam Becker. As you can see from the titles, quantum mechanics and reality are a hot topic 100 years after their foundation.
So what is the problem with quantum physics and reality? If you only want calculations for the construction of a laser or a computer chip, the answer is nothing . Quantum mechanics gives physicists hyper-accurate mathematical machines for manipulating the atomic world to exact specifications.
The problem arises when you ask a simple question like, "What is an atom?" Before quantum mechanics, you could have thought of atoms as little billiard balls. These were tiny "things" that, like the great things we encounter in our daily lives, have certain qualities, like their position or how fast they move. In other words, they were real in 19459011, just as we think it is for tables and chairs. This means that we believe that tables and chairs (and the other things we encounter on a daily basis) exist independently of us. That makes us in Smolin's words Realists about tables and chairs. Smolin believes that this kind of realism is about being a physicist:
"We realists believe there is a world out there whose properties in no way depend on our knowledge or our perception of it … We believe that too The world can be understood and described in enough detail to explain how a system behaves in the natural world. "
Unfortunately, the history of quantum mechanics has made it hard to be Smolin's version of realism about atoms , It is a field full of eeriness. For example, if you deal with quantum physics in the usual way, if you place an atom in a closed box with a dividing wall, then the atom will be present on both sides of the box at the same time . Only by opening the box (measurement) the atom "collapses" on one or the other side of the box. The experimental basis for this type of claim has already been described in two points at once by Ananthaswamy
. How can the atom be in two places at the same time? And why should the atom be compelled by viewing to choose one side or the other? Let's face it, tables and chairs do not behave that way. So the question is: how should we interpret quantum mechanics? The role of the measurement required to give the atom certain properties (such as position) really bothers realists. Measurements and observations are an integral part of the Copenhagen interpretation of quantum mechanics introduced by the Danish physicist Niels Bohr. Realists hate the Copenhagen interpretation. How then can the realism that we have over tables and chairs still be held for quantum phenomena on an atomic scale?
The answer for Smolin is that the craze that exploits realism from the atomic world is a fundamental problem of quantum theory as it is now. He sees the weirdness as "gaps and failures" that underlie "the fact that we have only achieved part of the solution of the central problems in science before we run out of air." For him, a deeper theory must exist that must be discovered.
The task that Smolin has set for itself is to show readers that there are already ways that could lead to a new theory that goes beyond quantum mechanics. To do this, Smolin begins the book with a clear explanation of the principles of quantum theory and where exactly what he calls the "anti-realist" focuses on measurements and observations. Then he leads the readers through a compelling tour of history, including a re-evaluation of the famous arguments between anti-realist Niels Bohr and the unrepentant realist Albert Einstein. Smolin's special focus is on American physicist David Bohm and his "pilot theory", where observers never saw reality on tables and chairs. The story of Bohm and other anti-Copenhagen quantum rebels was also best illustrated in Beckers What Is Real
Einstein's Unfinished Revolution when it comes to that Best is these basics for the realistic vs. antirealist arguments. Smolin's description of how quantum mechanics works is both elegant and accessible, using examples from the real world, such as the order in which you put on your clothes (underwear first and pants second and vice versa) to demonstrate a key quantum craze principle. His description of Bohm's alternative to Bohr's Copenhagen interpretation is also clear and will be helpful to non-scientists who seek to understand how these different interpretations find themselves and why they are important. If you want to understand the basic themes of these long-running debates as well as at least one alternative, you will enjoy this book. The last third of the book, in which Smolin formulates the direction in which it is now, may be a steep climb for some people – but it is still worthwhile to see where Smolin believes that lies lie.
Einstein's Unfinished Revolution has pleased me greatly . Just as I did the books by Ananthaswamy and Becker. Together, they demonstrate how alive this debate remains. Part of the fun of Smolin's book is simply not his kind of realist to me. Even if I use the terms "realism" vs. Using "anti-realism", we refrain from seeing the steep price that compels any interpretation of quantum mechanics to pay in describing the atomic world. There is no turning back to simple pictures of tiny little marbles leaping in the room. When it comes to the nuclear realm, there will be some kind of craziness. Until we have experiments that separate one interpretation from another (if we ever do), the real question is: what stupidity can we accept?
But Smolin articulates his position so clearly and skilfully that Einstein Unfinished Revolution will be useful if you agree, disagree or just want to learn some very cool ideas about physics and reality.
Adam Frank is Professor of Astrophysics at the University of Rochester and author of Light of the Stars: Foreign Worlds and the Fate of Earth . More of Adam can be found here: @ adamfrank4 .