Rather than imagining that we are somehow outside of the universe that physicists model, they should see our embedded intelligence as a central part of reality and as critical to what happens. Doing so can help make sense of the passing of time and our experience of free will, writes Jenann Ismael.

Any attempt to describe the universe as a totality inevitably involves self-reference. This isn’t something that one often confronts in physics. Most day-to-day physics is modelling other systems: cells, gases, planets. We maintain a separation of subject and object, or of investigator and system being investigated. And even though cosmology is explicitly devoted to the study of the universe as a whole, it is customary in cosmology to maintain the imaginative fiction that we – the people modelling the universe - are looking at it from the outside. We adopt, that is to say, the God’s Eye View. 

Ultimately, though, we are part of the universe. And that means that however we regiment the universe, whatever regime we work in, if we aim for a theory that describes all of existence, self-reference is unavoidable. Any system that is modelling the universe as a whole – aiming for full coverage of all of existence – is going to encounter self-reference. This is something that we can ignore in some contexts. It matters in others.

The people that have unavoidably encountered it are people who are trying to program an artificial general intelligence (an AGI).  They want to program a system with a bunch of general knowledge and the ability to model the world, and they are coming up against the fact that some of what happens is stuff that the computer does and that will give rise to the possibility of paradox. [1]

[1]Let me give you a simple example. Suppose we want to program a computer to serve as a grand overarching database for the universe: a repository of information about everything.  We begin by programming it with as much factual information as we can about the world. We program the laws of physics and all of the scientific knowledge we’ve amassed. We add the facts of history, what we know about the monkeys of costa Rica and the vast reaches of space. The goal is to be able to put any question of physical fact to it and the answer will appear in the output channel.

It is not, however, hard to find a factual question that it can’t answer truthfully. Ask it ‘is the answer to this question that’s about to be displayed in the output channel ‘no’?’. 

Think this through and you will see that any answer that it gives will be false. If it answers ‘yes’, clearly it is wrong, since that misdescribes what it wrote. And if it answers ‘no’, it is wrong as well. This might seem like a little logical glitch but its significance is profound.

These kinds of problems are familiar to philosophers and certainly to computer scientists. The problem arises because what the computer does in giving the answer interacts with what the answer says by rendering it false. And by saying things, the computer is doing things. There is interference between what it says and what it does.

This might seem like a little logical glitch but its significance is profound.