The Fabric of Reality

The Fabric of Reality, a 1997 book by David Deutsch, is full of great ideas, most of them surprising and intriguing. The main argument is that explanations are the centerpiece of science and that four theories play an essential role in our understanding of the world: quantum theory, the theory of evolution, the theory of computation and epistemology (the theory of knowledge).

You may raise a number of questions about these particular choices, such as why is the theory of relativity not there or why is the theory of evolution simply not a result of other theories in physics or even what makes epistemology to special. You will have to read the book to find out but the short answer is that not everything is physics and that theories at many levels are required to explain the world. Still, in physics, the most fundamental idea is quantum theory and it has profound impacts on our understanding of the universe. Perhaps the most significant impact comes from the fact that (according to Deutsch) what we know about quantum theory implies that we live in a multiverse. Each time a quantum phenomenon can conduct to more than one observable result, the universe splits into as many universes as the number of possible results, universes that exist simultaneously in the multiverse.

Although the scientific establishment views the multiverse theory with reservation, to say the least, to Deutsch, the multiverse is not just a theory, but the only possible explanation for what we know about quantum physics (he dismisses the Copenhagen interpretation as nonsense). Armed with these four theories, and the resulting conclusion that we live in a multiverse, Deutsch goes on to address thought-provoking questions, such as:

• Is life a small thing at the scale of the universe or, on the contrary, is the most important thing on it?
• Can we have free will, in a deterministic universe? And in the multiverse?
• Do computers strictly more powerful than Turing machines exist, and how do they work?
• Can mathematical proofs provide us with absolute certainties about specific mathematical statements?
• Is time travel possible, at least in principle, either in the physical world or in a virtual reality simulator?
• Will we (or our descendants, or some other species) eventually become gods, when we reach the Omega point?

The idea of the multiverse is required to answer most, if not all, of these questions. Deutsch is certainly not a parsimonious person when he uses universes to answer questions and to solve problems. The multiverse allows you to have free will, solves the paradoxes of time travel and makes quantum computers possible, among many other things. One example of the generous use of universes made by Deutsch is the following sentence:

“When a quantum factorization engine is factorizing a 250-digit number, the number of interfering universes will be of the order of 10 to the 500. This staggeringly large number is the reason why Shor’s algorithm makes factorization tractable. I said that the algorithm requires only a few thousand arithmetic operations. I meant, of course, a few thousand operations in each universe that contributes to the answer. All those computations are performed in parallel, in different universes, and share their results through interference.”

The fact that Deutsch’s arguments depend so heavily on the multiverse idea makes this book much more about the multiverse than about the other topics he addresses. After all, if the multiverse theory is wrong, many of Deutsch’s explanations collapse, interesting as they may be.

Still, the book is full of great ideas, makes for some interesting reading, and presents many interesting concepts, some of them further developed in other books by Deutsch, such as The Beginning of Infinity.

Portuguese Edition of The Digital Mind

IST Press, the publisher of Instituto Superior Técnico, just published the Portuguese edition of The Digital Mind, originally published by MIT Press.

The Portuguese edition, translated by Jorge Pereirinha Pires, follow the same organization and has been reviewed by a number of sources. The back-cover reviews are by Pedro Domingos, Srinivas Devadas, Pedro Guedes de Oliveira and Francisco Veloso.

A pre-publication was made by the Público newspaper, under the title Até que mundos digitais nos levará o efeito da Rainha Vermelha, making the first chapter of the book publicly available.

There are also some publicly available reviews and pieces about this edition, including an episode of a podcast and a review in the radio.

The Digital Mind: How Science is Redefining Humanity

Following the release in the US,  The Digital Mind, published by MIT Press,  is now available in Europe, at an Amazon store near you (and possibly in other bookstores). The book covers the evolution of technology, leading towards the expected emergence of digital minds.

Here is a short rundown of the book, kindly provided by yours truly, the author.

New technologies have been introduced in human lives at an ever increasing rate, since the first significant advances took place with the cognitive revolution, some 70.000 years ago. Although electronic computers are recent and have been around for only a few decades, they represent just the latest way to process information and create order out of chaos. Before computers, the job of processing information was done by living organisms, which are nothing more than complex information processing devices, created by billions of years of evolution.

Computers execute algorithms, sequences of small steps that, in the end, perform some desired computation, be it simple or complex. Algorithms are everywhere, and they became an integral part of our lives. Evolution is, in itself, a complex and long- running algorithm that created all species on Earth. The most advanced of these species, Homo sapiens, was endowed with a brain that is the most complex information processing device ever devised. Brains enable humans to process information in a way unparalleled by any other species, living or extinct, or by any machine. They provide humans with intelligence, consciousness and, some believe, even with a soul, a characteristic that makes humans different from all other animals and from any machine in existence.

But brains also enabled humans to develop science and technology to a point where it is possible to design computers with a power comparable to that of the human brain. Artificial intelligence will one day make it possible to create intelligent machines and computational biology will one day enable us to model, simulate and understand biological systems and even complete brains with unprecedented levels of detail. From these efforts, new minds will eventually emerge, minds that will emanate from the execution of programs running in powerful computers. These digital minds may one day rival our own, become our partners and replace humans in many tasks. They may usher in a technological singularity, a revolution in human society unlike any other that happened before. They may make humans obsolete and even a threatened species or they make us super-humans or demi-gods.

How will we create these digital minds? How will they change our daily lives? Will we recognize them as equals or will they forever be our slaves? Will we ever be able to simulate truly human-like minds in computers? Will humans transcend the frontiers of biology and become immortal? Will humans remain, forever, the only known intelligence in the universe?