Reality check: could our universe be a simulation?

Are we all living in a computer simulation? Is the world we imagine to be real simply virtual reality instead, an elaborate computer program? That sounds ridiculous, but nonetheless it’s what many clever people actually think — or at least, think possible. One of them, the philosopher David Chalmers, has just written a book on the subject, Reality +: Virtual Worlds and the Problems of Philosophy.

Chalmers is a serious intellect. He won a bronze medal in the International Mathematical Olympiad as a child and did his undergraduate studies in Pure Mathematics before turning to philosophy.

Part of his argument is that we are already building simulated worlds ourselves — computer games as well as virtual environments like Second Life. These are becoming increasingly realistic. In time — Chalmers estimates about 100 years — they will be indistinguishable from the physical world and people will spend their lives in them. By then it will also be possible to create many different universes, and the population of these multiple simulations will far exceed that of the physical world. Who can say that this hasn’t already happened and we are living in one ourselves? ‘There’s reason to take the idea seriously,’ Chalmers says.

One upside of this notion is that God might exist — but in this scenario, he’s the geek running the simulation. The downside, however, is that the geek-God might become bored and delete us. ‘This,’ Chalmers says, ‘is one of the things that worries people. If we’re in a simulation, could the simulators get bored and turn it off? Or maybe the moment that we realise that we’re in a simulation, that’s going to be the cue for them to do something. So yeah, maybe that’s something to worry about.’

Born in Australia, Chalmers today teaches philosophy and neural science at New York University. The 55-year-old is one of the most important philosophers today, existing in an exclusive club of living thinkers who are on compulsory reading lists for undergraduate philosophy students. His most famous book, The Hard Problem, inspired the title of Tom Stoppard’s 2015 play.

In the world of philosophy, he is a rarity. He writes with admirable clarity and there’s something quite rock’n’roll about him — his hair used to be prodigiously long, and he has written a heavy metal song entitled ‘The Zombie Blues’, a tongue-in-cheek number he belts out when the occasion demands, which asks whether it matters that we could all be empty inside.

His latest book is peppered with pop culture references rather than esoteric footnotes: he quotes ‘Bohemian Rhapsody’, not Borges. ‘I spend a lot of time watching TV and going to movies,’ he says. ‘In this book I’ve tried very hard to start every idea with something concrete. Science fiction and other corners of pop culture just turn out to be such great devices for doing that.’

During the pandemic, Chalmers has been meeting virtually with friends, though not yet in a fully simulated world. They choose a place and then put on virtual reality headsets. At once, they are all together in the city of their choosing, chewing the philosophical fat. Why did Chalmers describe consciousness as a ‘hard problem’? Because, he says, there are plenty of easy problems about consciousness, like finding out which parts of the brain light up in an MRI machine. But the hard problem is: why does consciousness exist at all? How does matter, the interactions of neurons in our head, become mind?

This is a philosophical question that has been debated for centuries, without coming to any conclusion. One view is that of the philosopher Daniel Dennett: consciousness is not a problem at all, it is merely a delusion that enables us to function. But who, then, is being deluded? There are some who believe the problem will be solved once we have found the right science.

Then there are two other consciousness crews: the mysterians believe we are not equipped to understand consciousness. We are just too thick. We can’t use the tool to find the tool. Then there are the pan-psychists, who believe that everything — all the way down to rocks and elementary particles — is to some degree conscious. Rocks aren’t quite self-aware, but consciousness is a property built into every atom in the physical world.

Chalmers does not align himself with any of these positions, but he sounds pretty close to panpsychism to me. ‘Consciousness may be to some degree fundamental,’ he says. ‘It seems that some kinds of physical systems are conscious, and many other systems are not. So, we can at least raise the question, which aspects of the physical world are associated with consciousness?’

What about the idea that we are living in a simulation? It seems like a whole new field, yet it isn’t really. The question of whether the outer world is real is nearly 400 years old. It was René Descartes who asked if we are being fooled by an evil demon into thinking this is all real when none of it is. But Descartes decided that the one thing he could be sure of was his own self-consciousness, proclaiming cogito ergo sum — ‘I think therefore I am’.

People who worry about this sort of thing have acquired a bad reputation. It is the kind of topic that makes it hard to separate the philosopher from the stoner. When the philosopher George Berkeley said he had concluded that the outside world was an illusion, Dr Johnson kicked a rock with almighty force, turned to Berkeley in agony and said: ‘I refute it thus.’

But it fascinates philosophers, because finding an answer has been so elusive. The simulation theory is just the old question’s latest clothes. ‘For many people the simulation idea is an updated version of Descartes — I am in a simulation, therefore nothing is real. I can’t rule out that we’re in a simulation. But I disagree with Descartes when he says that in a simulation nothing is real.’

And here we come to the heart of the matter. If you put on one of those virtual reality headsets and find yourself in a world of dragons, or just talking to your friends in an imaginary café, then you will naturally think these things aren’t real. But, for Chalmers, virtual objects are as real as ‘real’ objects.

‘There’s this naive picture of reality we have, like a Garden of Eden in which there are coloured objects laid out there in space and time,’ he says. ‘But the more we look at the world described by science, the more we see that underneath it’s very, very different. And that’s a step towards physical reality being a kind of virtual reality.’

But how is the physical world so different from the world we perceive? It’s a bit like that old question, often attributed to Berkeley, that if a tree falls in a forest and there’s no one there to hear it, does it still make a sound? To philosophers like Chalmers, the answer is no. The impact of a tree hitting the forest floor creates compression waves in the air around it — but until there’s an ear to hear those waves, they don’t become a sound. The same can be said for colour: it is a relationship between certain receptors in the eyes and the reflective properties of different materials. An apple, as science describes it, doesn’t have a colour, a taste, or a smell until there’s a person there to experience it.

Perhaps the physical world is more of a virtual world than we initially thought, but why does any of this matter? The answer is: because we seem to be on the verge of becoming God-like geeks ourselves. Mark Zuckerberg has distanced himself from the endless crises of Facebook by creating a new holding company called ‘Meta’. His goal now is to create a ‘metaverse’, an entire alternative world in which we live our lives. The term comes from a science-fiction novel by Neal Stephenson called Snow Crash. There the metaverse is just a virtual urban street. But Chalmers thinks Zuckerberg has slightly different ideas.

‘The way Zuckerberg seems to be using it is as the sum total of all virtual worlds. There will be this thing which is the metaverse which is the total virtual universe. I think Zuckerberg is now understanding the meta-verse as the successor to the internet… What I am reading into this is he wants Facebook to control the whole virtual world.’

Given Facebook’s rare talent for making the world a worse place, this sounds terrifying. Indeed, Louis Rosenberg, an early pioneer of virtual worlds and AI, has warned that such technologies will eventually ‘make reality disappear’ altogether.

Whatever Zuckerberg and others come up with, full virtual reality is still a long way off. As you may have noticed, the characters in current computer games or in VR conferences look nothing like real people. The one exception, perhaps, is Mark Zuckerberg, who looks identical in both worlds.

Chalmers admits we are a long way from convincing virtual reality. ‘The technology is primitive for now, no question about it. It’s moving ahead slowly and there are still these rather embarrassing headsets you must wear that present largely cartoonish characters. Will we have these amazing worlds in ten years as some people think? No, probably not. But I’d guess within a century we’ll be likely to have virtual worlds that are very close to indistinguishable from the physical world.’

If we are all racing (however slowly) towards the metaverse, should we be worried? ‘There are elements of utopia and there are elements of dystopia,’ Chalmers says confidently. ‘You can see amazing potential for transformed experiences, and immortality and forms of life that we couldn’t previously imagine. But people worry about losing the old forms of life. People worry about machines taking over. I don’t want to predict whether that will happen, but it’s no part of my vision of virtual reality that we abandon physical reality.

‘Once we’ve got virtual worlds indistinguishable from the physical world, people will sometimes want to hang out in the regular physical world and that will be regarded as a valuable thing to do. Just as people who are in cities often find it valuable to go into the country.’

He warns, however, that there will be a price to pay for clinging to biology. ‘People who are running on their old biological brains are ultimately going to be running at a much slower cognitive speed than people who have been uploaded, so it may be that the physical world becomes regarded as something of a backwater. I can understand having a negative reaction to that. But on the other hand, this sort of thing is common with all kinds of technological change.’

If we really are just lines of computer code, then it also opens up the idea that we could be immortal. ‘If we’re in a simulation, it obviously raises certain possibilities that, for example, creatures from a simulation could then be uploaded into different simulations at the end,’ says Chalmers. ‘There’s a certain kind of simulation where all this could happen as a matter of course. Maybe there could even be analogues of reincarnation.

‘I’m not saying I take this especially seriously. I’m not inclined to orient my whole life around it. But having this as a possibility has at least made me take thoughts and ideas about immortality and reincarnation more seriously than I did before.’

Chalmers’s book and, indeed, his entire way of thinking can be seen as genial provocation. Much of it feels like a whack-a-mole party where he gleefully sets up arguments, then knocks them down. For him the arguments, right or wrong, good, or bad, are commentaries on the state of our world. ‘I’m not really arguing that these hypotheses are true — instead, I’m thinking about what they say about the world, and what follows from them.’ Or, as he concludes: ‘Once we see the similarities between virtual reality and physical reality, it will make it easier for our minds to know the world.’