In a thought-provoking conversation with Tyler, Oxford professor and theoretical physicist David Deutsch explores his belief in the multiple-worlds interpretation of quantum mechanics, the concept of maximum freedom within the universe (or multiverse), and the potential for human understanding of these complex concepts.
Philosophical Modal Realism
The philosophical modal realism of David Lewis, which posits that all possible worlds are as real as the actual world, is discussed.
While there are interesting parallels with Deutsch’s own views, the overlap between Everett and Lewis is seen as more coincidental than illuminating.
Universe Forking and Decision-Making
Every decision we make could potentially create a fork in the universe, leading to different versions of ourselves making different decisions.
However, humans are error-correcting entities, meaning it would take more than just a random event to make a significant difference in our decisions.
Rejection of Simulation Theory
The idea that we are living in a simulation is rejected.
Living in a simulation would mean that there is a barrier beyond which we cannot understand.
If we were living in a simulation running on a computer, we would not be able to tell what the computer is made of or whether it obeys the same laws of computation like Turing computability.
Rejection of the Anthropic Principle
The anthropic principle, which suggests that the universe is structured in such a way that life as we know it can exist, is rejected.
The universe, or multiverse, is not beyond our understanding and we have the capacity to comprehend its nature and workings.
No Limit to Human Understanding
There is no limit to human understanding.
There is no barrier set by the universe that limits our understanding.
Believing that there is such a barrier is equivalent to believing in the supernatural.
Multiple-Worlds Interpretation
The multiple-worlds interpretation of quantum mechanics is a key belief of David Deutsch.
He asserts that the universe, or multiverse, is not beyond human comprehension and that humans within it have maximum freedom.
This belief extends to the idea that a person is essentially the running program in their brain.
The Concept of Possible Worlds
Possible worlds are determined by the laws of physics.
The universe we live in is demonstrably affected by things not in it, a lesson learned from interference phenomena.
Therefore, there are no laws of physics for our universe, just the laws of physics in general.
Many-Worlds Interpretation and Infinity
The relationship between the many-worlds interpretation of quantum mechanics and the view that our current universe is infinite is explored.
There’s no overlap between these two notions of infinity.
When an experiment can go one of two ways, the influence of that spreads out, causing differentiation in the universe.
I believe that there’s nothing to me except this running program in my brain and if that program were to run somewhere else and stop running in my brain then I wouldn’t notice anything and I would indeed have traveled to that other place. – David Deutsch
Implications of Gödel’s Theorem
Gödel’s theorem and its implications for understanding are discussed.
Even within pure mathematics, there is no such thing as a solid foundation for all our knowledge.
We can never know anything for certain, but we can have knowledge.
Understanding and Explanatory Knowledge
Understanding is always explanatory.
There is a differentiation between the fixed knowledge that animals have, which is encoded in their genes, and the explanatory understanding that humans possess.
Animals act according to fixed knowledge, while humans act according to their understanding.
There’s no such thing as the laws of physics for our universe, there’s just the laws of physics. Of course, we don’t know for sure what they are, but our best theories, in particular quantum theory, say that there are other such entities and how they affect ours and how matter behaves as a result of that. – David Deutsch
Positivism and Instrumentalism in Physics
The domination of physics by positivism and instrumentalism, which contaminated the field towards the end of the 19th century and the beginning of the 20th century, is criticized.
This had a knock-on effect on physics and almost had the same effect on relativity.
The Multiverse as a Continuum
The multiverse can be viewed as a continuum of universes, similar to a continuum of times or geological strata.
There’s no definite point of splitting, but rather a gradual change where some universes gradually change to one thing while others gradually change to another.
