In this blog post, we explore how the universe operates like a quantum computer and the new paradigms this creates, based on Seth Lloyd’s ‘Programming the Universe’.
‘In the beginning, there was the bit.’ Anyone unfamiliar with this book might find this statement somewhat puzzling. They likely know bits only as a unit of data size. Modern physicists are primarily interested in two major questions. The first is what the universe is made of, and the other is how the universe operates. The author of this book, Seth Lloyd, seeks to explain the nature of the universe based on decades of research in the cutting-edge field of ‘quantum information science’. He argues that to interpret all phenomena in the universe, we must understand the universe as a quantum computer. From here on, I will examine Seth Lloyd’s claims and then organize my own thoughts.
At the core of the principle driving the cosmic computer lies the laws of quantum mechanics. The universe is an intricate information-processing device that performs calculations on the information it contains according to the laws of quantum mechanics. Scientists have researched the feasibility of implementing such a device and have conducted actual experiments. This is precisely what a ‘quantum computer’ is. In other words, the very concept of a quantum computer is modeled after the universe. To explain the fundamental quantum superposition phenomenon underlying these laws, the author cites Jorge Luis Borges’ short story “The Garden of Forking Paths.” In this strange garden, all possible outcomes occur, and each outcome becomes the starting point for the next branch. This is similar to the well-known butterfly effect concept: even if paired particles are extremely far apart, a single fluctuation can affect the other, and if they are quantum mechanically entangled, a small change can lead to different outcomes. This is called quantum superposition or entanglement and is the most important theory in modern quantum mechanics. Modern physics places great importance on symmetry, so all particles exist in pairs. These paired particles influence each other regardless of distance; a change in one affects the other. For example, suppose one particle spins counterclockwise and the other spins clockwise. According to quantum mechanics, before observation, we do not know the direction of rotation for particles 1 and 2; we only know they rotate in opposite directions. At this point, if particle 1 is observed to rotate counterclockwise, particle 2 is determined to rotate clockwise, and if particle 1 is observed to rotate clockwise, particle 2 is found to rotate counterclockwise. The two are always correlated.
Because the laws of quantum mechanics differ from those of classical mechanics, quantum computers governed by quantum laws are also significantly different from the classical computers we commonly encounter. As is well known, the basic unit of information processing is the bit, which carries either 0 or 1 of information. However, recalling the concept of superposition in quantum mechanics, a bit in the quantum world—a quantum bit (qubit)—can simultaneously represent two events that can never occur together: 0 and 1. Quantum computers can utilize this superposition, processing information using qubits to perform highly complex and intricate calculations all at once. Quantum computers can simulate physical systems that classical computers cannot simulate; this is precisely the quantum computation the author describes as being performed by quantum computers.
The author expects that the ‘computational universe’ perspective, which understands the universe as a single quantum computer, could more efficiently explain the universe’s complexity and order. According to Boltzmann’s explanation, the universe’s complexity arose from chance. However, it fails to explain the universe’s fascinating ongoing order and complexity. The author believes the inherent richness and complexity within the computational universe’s information processing can efficiently account for this complexity and order. According to his perspective, even at this very moment, the universe we inhabit is continuously performing calculations about itself—composed of quantum bits—and processing information, following the intricate laws of quantum mechanics. All the wonders of nature are expressions of the universe’s quantum computational power. To explain what could not be accounted for by the chance-dominated world envisioned by Boltzmann, the author introduces the perspective of a “computing universe,” presenting it as a new paradigm.
This is how Seth Lloyd sought to explain the universe. After reading this book multiple times and reflecting on whether I can agree with the author’s argument, my answer is ‘yes.’ This theory, like string theory, can explain the universe, but it faces the challenge of lacking clear experimental evidence. However, while string theory relies on the somewhat unconvincing existence of ‘strings’ to explain everything, the framework Seth Lloyd describes is flawlessly elegant. Comparing classical machines and quantum computers made me think of clocks and computers. A clock is a highly classical machine, its complexity and technical sophistication immense. But if a clock malfunctions and runs one second slow, even after a long time, it remains just a clock one second slow—no further change occurs. This is precisely the nature of classical machines. Computers, however, can undergo significant changes in output from small inputs during programming, and these changes are sometimes unpredictable. The author explains multiverse theory and cosmology by drawing parallels to such computers, combining existing theories with his own. Observing this, I found the absence of errors to be a major strength of this theory. Furthermore, the explanation linking it to the well-established theory of thermodynamics was sufficiently persuasive to me. There is a saying: ‘Information gains meaning as it accumulates. Information is accumulation.’ Information itself is a record of events occurring over time, and as time passes, information accumulates and gains meaning when it does not disappear. The Second Law of Thermodynamics, one of the most fundamental laws of the universe, states that the universe’s entropy—that is, disorder—always increases. This increase in entropy also carries the meaning of accumulation. The fact that a new explanatory framework can be connected to and explained by already established theories also provides grounds to support this argument.
If Newton’s world was a simple machine, the world proposed by Seth Lloyd is a vast information system composed of bits and a quantum computer that processes that information. This incorporates the essential elements of quantum mechanics: quantum superposition of multiple states and probabilistic randomness arising from measurement. This makes the universe operate very differently from classical machines, enabling the rich expression of the existing universe. I believe this new explanatory framework is error-free in describing the current universe. Developing this view further, I think it could even offer information as a solution to the greatest challenge facing scientists: the theory of everything—a unified field theory that explains all forces and phenomena in the universe. If the universe could be explained as one entity through a unified field theory, its convenience would be beyond words. If the author’s view holds true, the universe operates like a quantum computer, and I believe it is possible to establish a system where all phenomena and forces that occur can be explained as information. I think research should proceed further in this direction.
