Author: Tim Dean, Honorary Associate in Philosophy, University of Sydney

How do you know that we aren’t in virtual reality right now? It could be so realistic that it feels like normal life. – Erin, 13, Strathfield.

Have you ever had a dream where you thought everything around you was real, and then you wake up and realise it was all a dream? If so, how do you know you’re not dreaming right now?

The Chinese philosopher Zhaungzi had this very thought more than 2,000 years ago. He woke up from dreaming that he was a butterfly, but then couldn’t be sure that he wasn’t a butterfly dreaming he was a man.

It is easy to believe the world around us is real. But it’s possible that it’s a dream or a very complex computer simulation. Maybe we’re all plugged into a very powerful computer that is providing us with a virtual reality experience that makes us think we’re somewhere else.

If the simulation is really good and looks like the real world, we might not know we’re in a simulation.

So the short answer is we cannot ever be absolutely 100% certain we’re not in a computer simulation, or that we’re dreaming instead of being awake.

But while this might seem like a strange or disturbing thought, it actually makes no difference to the way we live.

If you have friends and family, and things you enjoy doing, it doesn’t really matter if they’re a part of a dream or a simulation, because you will still behave in the same way.

You’ll still be nice to your friends, you’ll still love your family (even if they might annoy you), you’ll still enjoy the taste of your favourite foods, and you’ll still hate getting up early in the morning.


Children can have their own questions answered by experts – just send them in to Curious Kids, along with the child’s first name, age and town or city. You can:

This article is republished from The Conversation under a Creative Commons license. Read the original article.