New Scientist - USA (2022-01-29)

29 January 2022 | New Scientist | 49

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questions about ordinary physical reality.

Things like: how can we know about the

external world? What is it? What is the world

made of? How do mind and body interact?

Is there a god?

“How can we know about reality?” was

a question philosopher René Descartes

posed in the 17th century. Can virtual

worlds finally help us answer it?

I think, at the very least, virtual worlds provide

a particularly pure illustration of Descartes’s

problem. He said: “How do we know we’re not

dreaming? How do we know an evil demon

isn’t fooling us?” These days, we can just ask

how we know we’re not living in a simulation

like in The Matrix, where there’s in effect a

giant computer program modelling the world

that’s generating your experiences, and none

of it is in fact “real”. Descartes’s thought turns

essentially on the idea that if you’re in one

of these simulation-like scenarios, the world

that you experience doesn’t really exist. What

I want to argue instead is that such a virtual

reality is still genuine. I still have hands, there

are still tables and chairs and books, there are

still people I’m interacting with. Everything

is still real, it’s just digital.

Isn’t that what many physicists argue is true

of “real” reality anyway?

Yes, it goes back to the physicist John Wheeler

and his “it from bit” idea. That’s been

interpreted in many different ways, but the

basic idea is that physical objects out there –

cells, molecules, atoms – are ultimately

grounded in a level of bits, of binary

information. In that scenario, no one says,

“Ah, if the world is made of bits, then none of

this is real”. Likewise, if we were to find out we

were in a simulation, we say, “OK, physical

objects are still real, we just found out there is a

level of computation, a digital level, underneath

the level of physics”. If we’re in a simulation

running on a computer in the next universe

up, maybe the digital level itself has got levels

beneath that, maybe with our simulations

within simulations. Maybe we’re at level 42.

There are many productive connections to

be made between the simulation idea and

this idea from modern physics.

Why should we believe we are in a simulation?

You can make many of the points I make

while being totally agnostic on whether we are

in a simulation. I believe we can’t rule it out,

because, basically, our evidence about reality is

indistinguishable from the evidence we would

have in a perfect simulation. You might say,

“Here’s some proof that we’re not in a