Quantum Supremacy by Michio Kaku

Published by Doubleday on May 2, 2023

Quantum Supremacy is nonfiction, although it explores a topic that might interest fans of science fiction. The book’s premise is that quantum computers are the key to unlocking the mysteries of life and solving many of the world’s problems. Most of the book consists of bite-size descriptions of big problems and barriers to fixing them, barriers that might be overcome by greater computing power.

Quantum computers are in their infancy. They have the potential to dwarf the ability of digital computers to analyze vast amounts of data. They do this by dancing on top of many atoms simultaneously. Okay, that’s not what they do, but that’s my interpretation of a fascinating topic that is far too complex for my simple mind to wrap around.

Michio Kaku discusses the history of computing before he explains quantum theory. Science fiction fans know quantum theory posits that two particles can be in two different places at the same time and, no matter the distance between them, can be in instantaneous communication. That’s a pretty good trick.

No matter how many times I try to digest simple explanations of quantum mechanics, I fail. That's not a knock on Kaku. I give him credit for writing a simple, cogent explanation. I only wish I could understand how the cat in the box can be both alive and dead until someone opens the box. But as Kaku explains, a theory isn't necessarily wrong simply because it intuitively seems nonsensical.

The ability of distant particles to have the same immediate experience is known as quantum entanglement. Quantum computers, as I understand it (or, more likely, misunderstand it), compute using atoms rather than transistors, which allows them to perform computations simultaneously rather than serially. Entangled atoms interact with each other, allowing a bunch of atoms to get in on the act, processing problems more quickly than a bunch of 0s and 1s can manage.

So what does the quantum revolution promise? Chapter by chapter, Kaku discusses problems that are too complex for digital computers to solve, then speculates about the ways that quantum computing might produce breakthroughs. He suggests that quantum computer might help scientists:

•   discover how life originated;
•   understand photosynthesis;
•   develop more efficient ways to produce food;
•   develop batteries with more efficient energy storage;
•   cure cancer, dementia, and other complex health issues;
•   increase lifespans;
•   solve the problem of global warming; and
•   understand the universe.

Now, science fiction fans have read plenty of stories about artificial minds becoming so smart that they decide to control or wipe out primitive humans. Kaku doesn’t explore the potential downside of quantum computing, which I count as a significant strike against a surprisingly pollyannish book. He discusses the wonders that ever-smarter Artificial Intelligences will bring without saying much about the difficulties that AIs are currently causing, beginning with lazy students who have an AI write their term papers. As tradeoffs go, I’ll put up with sneaky students gaming their teachers in exchange for curing cancer. Still, it seems to me that there must be potential downsides to quantum computing that are worth acknowledging.

My other knock on the book is that Kaku is a physicist who, while obviously a very bright scholar, spends much of his time talking about issues of science that are outside his field: medicine, biology, agriculture, climate science, and so on. We are thus fed basic information that most of us have already seen about the health and environmental challenges our civilization faces. This seems to me to be a way to turn an essay about the physics of computation into an expansive book that often relates to physics only tangentially.

The book is informative, but less than half of it directly addresses quantum computing. I might have preferred a shorter essay without all the extraneous information about (for instance) how cancer develops and how carbon dioxide emissions are affecting climate. The book provides an overview of many familiar subjects when what I wanted was a book that would drill down on the topic of quantum computing.

We’ve all learned from the computer age that information is priceless. I can’t condemn a book for being informative, so I’m recommending Quantum Supremacy. I only wish I could connect a quantum computer to my brain so I could make sense of the fascinating world of quantum mechanics. Maybe that’s next on the horizon.

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