We contemplate the physical universe in terms of atomic particles, their energy, mass, charge, spin, and macroscopically, products that emerge from combinations of individual particles, such as compounds, liquids, gases, solids, atmosphere, water, organic material, crystals, living beings, atmosphere. Take a harder look. At the core of the physical universe is information. Information is physical. It is both visible and invisible. Invisible information is neither spirit, ethereal, or non-material; we can't see it because it is simply too small for our human sensory tools to see. Information is exchanged between particles at an atomic level by their collision, not unlike an exchange of information caused by photons colliding with the lens of an eye, subsequently triggering a movement of neurons and chemical reactions that triggers or creates a memory in the mind.
Until I read Programming the Universe, I was uncomfortable with the idea that the mind was a computer, as espoused by Steven Pinker and others. Perhaps I was just uncomfortable with the analogy. Not because of an attachment to Cartesian duality; more likely because of an emotional need to see the mind as something more than an input/output device. Whether we regard the mind as a computer or not, the fact is that the mind processes information, and Seth Lloyd demonstrates that processing -- computing -- information is what the universe -- not just life as we humans know it -- is all about. Our mind is just an evolved manifestation of the computational activity that is happening everywhere else around us.
University of California philosopher, John Searle, denies the physical nature of information, "except for information that is already in the mind of some conscious agent." (The Mystery of Consciousness (1997)) "Information," he says," does not name a real physical feature of the real world in the way that neuron firings, and for that matter consciousness, are real physical features of the world." While our mind has a way of creating the illusion that there is a non-physical attribute to our thoughts and that categories of data or information are somehow separate from our consciousness, I find it difficult to understand how Professor Searle succumbs to this illusion even "in part." Lloyd challenges this view.
The physicality of information is not what Lloyd's book is really about, although it is a significant insight. The book is about a scientific revolution in our understanding of information -- how the classical understanding of information that was essential for the development of computer science 60 years ago is now being gradually replaced by our understanding of quantum information -- in part thanks to quantum computers that can engage in computational activity that are beyond the capabilities of classical computers. There is a direct parallel here with classical physics and quantum mechanics, and understanding the relationship between a physical reality we can "see" and the physical reality we cannot see, but we can know. If this sounds like science fiction or even religion, it is not. If you are a dualist or a closet dualist, this book will make you think twice (if you are prepared to).
The universe computes by taking measurements. When something is measured, the universe "sees," "hears" -- type in any sensory reaction here, not necessarily limited to human senses and consciousness -- and the universe takes account of information. So atoms colliding in another galaxy and photons hitting the lens of an eye are no different.
Werner Heisenberg taught that the object of a measurement will destroy other complementary information, which becomes unmeasurable -- the uncertainty principle. Do we mean "destroy?" No, after all, Schrodinger's cat did not necessarily die in the quantum universe. Welcome to Entropy 101, a significant teaching of Lloyd's work and others who have mined the field of the theory of information and quantum information. The first and second laws of thermodynamics are active here. Information, like energy, cannot be destroyed (or increased) --- it is conserved (the first law) and entropy increases (the second law).
Whoever said that entropy is a measure of disorder did the world a disservice. The statement is literally true, but under the second law disorder does not increase -- just the opposite. In thermodynamics, entropy classically refers to the dispersal of energy over time and a balance between energy and work -- temperature, pressure and density tending to find a stasis. But, more generically, what is really meant by entropy is that, over time, the probability of equilibrium or stasis or more stable outcomes increases. As a measure of information, when entropy decreases, our measurements record less likely physical outcomes. As entropy increases, our measurements record more likely physical outcomes.
A complementary treatment of this subject is also found in Charles Seife's book --- written the same year that Lloyd's was published --- Decoding the Universe (2007). Seife is one of the best popular science writers, and here I found one of the most accessible discussions of black holes and what happens beyond the event horizon, where information appears to disappear (or does it?). Lloyd's additional contribution comes from connecting information theory to complexity theory -- emergence and self-organizing systems. For those who have followed the work at the Santa Fe Institute and scholars such as Stuart Kaufmann on the subject of dynamic living systems, this chapter will be rewarding.