The Fabric of Reality

Summary

The Fabric of Reality presents a bold, interdisciplinary exploration of the nature of reality. In it Deutsch tries to merge concepts from quantum physics, epistemology, computation, and evolutionary biology into a singular explanation of the world. His main idea is to explain all the important knowledge of the world in one book => a tall order, but I think he has succeeded in doing so.

Deutsch's central thesis is that we can synthesize and create a "theory of everything". He doesn't mean that in the sense of just physics... The standard model + gravity does not equal a theory of everything... No.

The deepest understanding of reality requires integrating distinct but interrelated scientific theories. And he claims that such an understanding is still possible, even when the complexity of scientific knowledge and inquiry has drastically increased. This increase (and where it will eventually lead) is the topic of the sequel to this book: The Beginning of Infinity.

The fundamental ideas and how they inter-relate are what he outlines in the Fabric of Reality. These ideas are:

• Quantum Physics: Specifically, the many-worlds interpretation of quantum mechanics. This interpretation suggests that all possible outcomes of quantum events are realized, meaning that the universe continually splits into a multitude of parallel universes. For an idea of how this sort of block universe affect our understanding of time, check out The Order of Time by Carlo Rovelli.
• The Theory of Emergence: The idea that complex systems can exhibit properties that are not present in their individual components. In a way, the trajectory that the world is evolving is governed more by the emergent properties of living organisms and the systems that they build rather than the fundamental forces of physics. Life is not directly described in physics, yet how a star evolves is fundamentally changed once a life form is building a dyson sphere around it.
• The Theory of Computation: Grounded in Turing's theory of computation, which explains the power and limitations of computational processes, but expanded to include quantum computation and it's possibilities.
• Epistemology: How science and the scientific method (as described by Karl Popper) can lead to knowledge generation and understanding of the world and how philosophically this is the only method of generating truth and explanations that we know to be working.
• The Theory of Evolution: Primarily Darwin's theory of natural selection, which Deutsch extends to all domains where knowledge grows, not just biology. He suggests that knowledge evolves similarly to biological traits, through variation and selection processes. This is the same idea of "memes", also described by Richard Dawkins in his book The Selfish Gene.

To me, one of the best ideas of the book is David Deutsch's idea of "wealth". I regularly explain this concept to other people. In his own words:

Wealth is not a number. I don't think it can be characterized very well by a number. It is the set of all transformations that you are capable of bringing about. That is your wealth. And if optimism is true, then there's no limit to wealth.

This idea is so powerful because it shows that wealth is not a zero-sum game. It's not that if I have a lot of wealth, you have less. No. Wealth is the ability to transform the world around you. And if you can transform the world around you, you can create more wealth. And if you can create more wealth, you can transform the world around you even more. It's a positive feedback loop. Wealth breeds wealth. Focusing on this sort of wealth is what makes societies prosperous and also shows the flaws in our current conception of money and it's zero sum nature... especially when looking at stock markets and the sort of financial games that we play there. It doesn't add any new capabilities to the game. It's just a redistribution of capabilities, not an increase.

To sum up: Reality can be understood and the key parts to understand it are Quantum Physics, Emergence, the Theory of Computation, Epistemology, and a solid understanding of Evolution. Learning these concepts is achievable, and once we do, we will know how the universe works, we will understand the Fabric of Reality.