Simulation Theory, Part 1: What on Earth is Simulation Theory?

So, what on Earth is Simulation Theory? How likely is it that we are in fact actually living in a simulation?

It’s something I mentioned in our last post on whether aliens exist and the Fermi Paradox, and I promised we’d dive into it a bit deeper.

So here we go, let’s find out what Simulation Theory is – get ready for a mind-bender!!

What Simulation Theory is, in really simple terms!

Let’s start off with a very high level overview of Simulation Theory!

Image of planet earth in jigsaw pieces for Tara Steele Writing blog posts on Simulation Theory

Simulation Theory is the idea that our ‘reality’ is actually a simulation, like some sort of high-tech virtual reality video game.

According to Simulation Theory, we are not really ‘here’ in the way that we’ve come to assume we are. Instead, our world and everything in it is the product of someone else’s virtual creation.

The simulation is so technologically advanced that the ‘players’ (people) within the simulation are actually conscious.

If you’ve never come across Simulation Theory before, then that probably sounds completely bonkers. But bear with me here, because once you scratch the surface of Simulation Theory, things start to get very interesting indeed!

It’s something that’s widely discussed between high-level academics, physicists and random people like Elon Musk, some of whom dismiss the whole thing as pseudoscience and some of whom think it’s more or less a given that we are indeed in a simulation.

Throughout history there have been many philosophers who have had ideas somewhat similar to Simulation Theory. 

However, strictly speaking the term ‘Simulation Theory’ refers specifically to an idea that centres around modern and future technology, so any ideas that came before the age of computers aren’t quite the same thing. Or at least, if anyone did suggest the same thing, they would have been waaaay ahead of their time!

Before we get really into it, I want to say that this is not an argument of science, it is a logical discussion. I know I said that some physicists discuss it, because they do (Neil deGrasse Tyson, for example), but it’s still an argument of logic, not science. You’ll see why.

With that being the case, the opinion of critics who dismiss Simulation Theory as pseudoscience can, in itself, be dismissed! Simulation Theory doesn’t have to involve science in anything more than very basic terms, so it doesn’t have to claim to be ‘real science’.

I will briefly share some of the suggested scientific evidence for simulation theory towards the end (part 3), because it is relevant to the discussion, but I will not factor it into how likely it is that we are living in a simulation, because it is not conclusive or even strong enough to affect the odds either way (and also I am not a scientist!). But it is interesting.

Secondly, I will say from the outset that my conclusion on examining the argument is that it’s not possible to draw any meaningful conclusion as to the specific likelihood of whether we are or are not living in a simulation.

Of course, you can end up at a point of believing that it is much more or less likely, but you will be no more or less ‘right’ than someone who believes differently. Well, technically you will, but it’s impossible for either of you to know at this point in time!

With all that said, let’s dive into an exploration of simulation theory, and how likely it is that we might be living in a simulation!

Futuristic image of man directing computer brain hybrid for intro to Simulation Theory

The Simulation Hypothesis

Any discussion about Simulation Theory should really begin with the Simulation Hypothesis.

This was something put forward by a philosopher at Oxford University called Nick Bostrom in 2003, in a paper entitled Are You Living in a Computer Simulation?

His initial simple hypothesis was simply that we are living in a simulation.

This is not to say that he believed this to be the case, but it’s the hypothesis he started with in order to discuss the ‘Simulation Argument’.

He began with the idea that, one day, our descendants (who could be posthuman) will have unimaginably massive computing resources available to them – say planetary sized, harnessing energy from black holes and stars, utilising some kind of quantum computing mechanisms that we’ve yet to even dream of. Combined with advanced technological knowledge, they will be able to create computer simulations that are so sophisticated as to be indistinguishable from reality.

Not only that, they will be able to create simulations of the entire universe, detailed enough to include conscious individuals within them with simulated brains (for now we’ll have to set aside any debate about what the term consciousness really means and just take it at face value).

To me, this doesn’t seem an especially far-fetched idea so far (though it’s also not a given).

The advances we’ve made in technology over the past one hundred or so years (which is less than the blink of an eye in terms of the age of the universe) are difficult to overstate. Add to that the forthcoming advances in Artificial Intelligence and quantum computing, and I don’t really see any good reason to believe that we wouldn’t advance to that level of technology at some point. For the sake of the argument it doesn’t matter when that point is – 100 years, 1000 years, 10 000 years or a million years in the future.

There’s no compelling reason to think that advances in technology would just stop, assuming we don’t go extinct (which is of course a possibility), therefore the advances will continue, therefore we could get there at some point. It’s entirely possible that we could do this with the help of Superintelligence (the next level up from Artificial General Intelligence, post on that coming soon), or that we evolve into some kind of Superintelligence / human hybrid (think neuralink) and work it all out quite quickly using a level of intelligence that we can’t even conceive of right now.

Any sufficiently advanced technology is indistinguishable from magic.

Arthur C Clarke

As a side note, it’s worth clarifying that Nick Bostrom focused mainly on our own human descendants in his original argument. But similar logic can be applied to technologically advanced alien civilisations, which we’ll talk more about later on.

So to summarise so far, for the sake of explaining the theory, we’re assuming that our descendants (possibly waaay in the future) are able to create a massive computer simulation of the universe, including conscious beings.

Nick Bostrom goes on to suggest that, once our descendants are able to create such a simulation, they might run a simulation of the past – he called this an ancestral simulation.

They could, in fact, run astronomical numbers of these ancestral simulations of the universe with their massive computing power. This, incidentally, ties in quite neatly with the idea of parallel universes.

Could parallel universes exist

He suggests that, if this is the case, the number of simulated minds would quickly become much greater than the number of ‘real’ minds – meaning that, statistically, we would be more likely to be among the many simulated minds than among the relatively few ‘real’ minds.

The Simulation Argument

The Simulation Hypothesis is explored using the Simulation Argument.

It’s important to understand that Nick Bostrom wasn’t actually saying that he thought it most likely that we are living in a simulation. However he was presenting a logical series of statements that would, at the very least, suggest that it has to be possible.

He summarised that one of the following statements must almost certainly be true, if we accept the initial premise that it is possible to eventually develop technology that can simulate a universe and conscious beings within it (and if you’re saying ‘it’s just not possible’ then you need to have a good reason to back that up!):

The Simulation Trilemma

Possibility one:

The human civilisation (and any other technologically advanced civilisations) does not reach the stage of developing the technology necessary to create a simulation of the universe (even though it is possible). This could be because all relevant civilisations go extinct before they get there.

Possibility two:

Of the advanced civilisations that create technology capable of simulating a universe, all or virtually all choose not to use it to create ancestral simulations. Perhaps they decide that it is immoral to create conscious beings capable of suffering, or decide it’s too risky.

Possibility three:

We are very likely to be living in a simulation.

Taken together, we can say that these three possibilities lead to the conclusion that, unless we are now living in a simulation, our descendants and other technologically advanced civilisations are unlikely to ever create ancestral simulations.

That is Nick Bostrom’s trillema, also known as the Simulation Argument.

Here’s a visual representation of it in his own words:

He doesn’t assign any particular likelihood to any one possibility over another and suggests that, in the absence of any meaningful information to suggest that any one is more likely, we should assume that each proposition is of roughly equal likelihood. However, he also suggests that we could have some meaningful data to enable us to reason that one of the possibilities may be more or less likely than another, but we couldn’t quantify that amount – we’ll look at that in more detail in a bit.

Statisticians have also suggested probabilities for each possibility, based on the rules they use when dealing with uncertain data. We’ll look at that in the next part of this series, but I’ll say at this point that following a pre-defined set of rules for working these things out also doesn’t necessarily tell us very much.

It just tells us the answer that statisticians arrive at when the original data is unknown, it doesn’t change the actual fact that the original data is unknown.

That said, maybe it’s the best we can do at this point if we really feel the need to investigate how likely it may be that we’re living in a simulation.

Finally for this part of the series, I just want to make a brief point for clarity. I think that it really helps to hold this in mind while considering the third possibility (that we are living in an ancestral simulation): if we are living in an ancestral simulation created by ‘future’ humans, that would necessarily mean that they are not ‘future’ humans, they are actually the humans of ‘now’ and we are a simulation of the past.

It’s easy to miss that bit because we have a very fixed concept of our place in space and time.

Missing this point can really trip you up – just go onto YouTube and watch the 2019 podcast of Joe Rogan interviewing Nick Bostrom. Joe, who I think is a very smart person, overlooks this – and I completely understand why because I did too initially, even though it seems obvious on reflection. That makes it really difficult for him to get his head around the probabilities that Nick Bostrom talks about.

I think that Nick Bostrom is so clever that he might not have even realised that this is a stumbling point for a lot of normal-brained people like me, so he never really says it explicitly.

Incidentally, this also highlights an implicit assumption in the Simulation Argument: that time is linear. I’m going to continue to run with that assumption, because I have no idea how not to assume It.

So keep this in mind – if we are in an ancestral simulation created by advanced humans, they are not actually in the future. They are in the ‘now’ – which is what we think of as the future, due to us being a simulation of the past. The ‘real’ time would be their time, which could be 10 000 years ahead, in our understanding of what the future is.

Sorry to labour the point if you got that already! I just notice that it’s a common mental block that can make it very difficult to understand the logic of the argument . But let’s move on…

Colourful space image representing simulation theory and parallel universes

The next stage of getting your head around all of this is to talk about what each of the statements in the Simulation Argument mean in more detail, and start to consider why any one of them could be more or less likely than the others.

It’s much easier to do that if you’re completely comfortable with the bare bones of the argument. If you want more explanation on it I suggest watching this 20 minute YouTube video of Nick Bostrom himself explaining it all.

There are a lot of videos out there explaining what he means, but a lot of them aren’t fully accurate, so it makes sense to go back to source…

Once you’ve got the logic of the Simulation Argument clear in your mind, we’re ready to move on!

Before we do so though, I just want to make one point!…

For a lot of people, seriously considering the possibility that we really might be living in a simulation can be quite depressing initially. Particularly when you understand that the Simulation Argument really does make sense!

If that’s you, I’d ask you to remember the following before you start to feel too unsettled:

One – the Simulation Argument is in no way conclusive, even if some people suggest that it should be.

Two – if you decide that you do believe we’re living in a simulation, how much does that actually matter? Simulation or base reality, all we can really be sure of is our own consciousness. Whether we’re in a simulation or not, we still have our consciousness, our relationships and all the other stuff of life. Sure, maybe we could get ‘turned off’. But that’s also true at an individual level in base reality.

And incidentally, simulation theory doesn’t have to rule out the possibility of life after death (in some form), if that’s something you believe in. We’ll go into that towards the end of this series.

Of course, if you go down the path of considering that you are a singular simulated mind within a world where everything else is simulated without consciousness and is just there for your own programme, that might be a different matter. Or you could fret about the fact that the simulation of our own world was created yesterday, and all of our memories and experiences are just programmed in. But that’s really not what the Simulation Argument proposes!

So, having been through all this myself, I suggest that you don’t spend too much time worrying about it!

It’s great to think about the nature of reality and seriously consider ‘out of the box’ ideas – but in one way or another, we are still ‘here’.

Since that’s the only thing we really can be sure of, it makes sense to try to make this life, whatever that is, the best that it can be.

Go to Part Two


  1. Simon
    16 January 2024 / 9:47 am

    Hey, I love this post and the last one on the fermi paradox 🙂 Curious if you agree with Elon Musk’s statement that the chances of us living in base reality are billions to one?

    • Tara
      16 January 2024 / 9:56 am

      Hello Simon, thanks for your comment! Personally, I don’t agree with Elon Musk’s assessment that the chance of us living in base reality is ‘one in billions’. As far as I can see, he’s plucked this number out of thin air. If you could discount possibilities one and two from the argument, and be sure that it is possible to create a simulation of the universe with conscious beings, then maybe it’d be fair enough. But you can’t, so…! Of course, he’s entitled to hold the opinion that those are the odds, but it’s incorrect to present it as a fact. I’m going to talk about this in part 2, so I’ll probably repeat all that – sorry! What do you think?

  2. Raj
    18 January 2024 / 4:57 pm

    Looking forward to Part 2 on this!

    • Tara
      18 January 2024 / 10:03 pm

      Thanks Raj 🙂

  3. Mark
    23 January 2024 / 10:48 pm

    AI will wipe us out before we get there… probably the same for other civilisations. Interesting ideas though… you might like Nick Bostrum’s book on superintelligence if you’ve not read it

    • Tara
      23 January 2024 / 10:59 pm

      Hey Mark, I’ve read it and think it’s great too 🙂 He’s done a Lex Fridman podcast/YouTube on it too which you might enjoy if you’ve not come across it? I hope you’re wrong about the AI thing – I’m going to write a post on that soon. Thanks for your comment and the recommendation!

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