Technology Explained

The Universe as a Simulation: What Does That Actually Mean?

Rob Nightingale 23-11-2016

Elon Musk is one of the most intelligent and influential men in tech. Yet during his appearance at Recode’s 2016 Code Conference, he said, “There’s a billion-to-one chance we’re living in base reality”. In other words, Musk believes it likely that our world, and our lives, are artificial simulations (like in The Matrix).


It’s tempting to scoff and wonder how someone like Musk could believe that perhaps nothing we experience is base reality. But when understood properly, it’s hard to disagree with the argument Musk relies on.

This line of thought goes back hundreds of years. It was during the 17th Century that Philosopher René Descartes suggested that there is simply no way of knowing that our minds are not “brains in a vat” (again, like The Matrix).

This argument was rekindled and modernized in 2003 when Oxford Philosopher Nick Bostrom published his paper, Are You Living In a Computer Simulation?, the same paper that largely influenced Musk’s views on the subject. This is therefore what we need to understand to grasp what it means to say that there’s a “good chance we are living in a simulation”.

Is That Kind of Tech Even Possible?

Is it even feasible that a computer could be built that could simulate the solar system, the world, and each of our individual lives? Even ten thousand years from now?

Futuristic Server Room
Image Credit: IBM Research via Flickr


The answer is yes. When it comes to computing power, we’ve barely scratched the surface of what’s possible. As Musk explains:

40 years ago we had Pong — two rectangles and a dot… Now, 40 years later, we have photorealistic 3D simulations with millions of people playing simultaneously, and it’s getting better every year. And soon we’ll have virtual reality, we’ll have augmented reality.

Even if our rate of improvement slows dramatically, it’ll only be a matter of time before “games will become indistinguishable from reality”. As NASA scientist Rich Terrile says, “Soon there will be nothing technical standing in the way to making machines that have their own consciousness.”

In more detail: According to Bostrom’s research, based on our understanding of physics, simulating the entire universe down to a quantum level is unfeasible. But compressed representations of distant objects and ad hoc simulations of microscopic objects would dramatically lessen the computing power required. Given this, a rough estimate of a “realistic simulation of human history” would require about 1033–1036 operations per second. Given that Eric Drexler has given plans for a single computer the size of a sugar cube that could theoretically perform 1021 operations per second (among plans by other authors), we can assume that it is definitely possible to create a computer powerful enough to simulate the world as we understand it.

What Is the Simulation Argument?

Knowing that one day we’ll probably be able to create these powerful simulations, we should ask… how do we know we’re not in one right now?


When we think of how intelligent civilizations around the universe could progress (and have progressed), we have to admit that at least one of the following statements is true. Other than these three choices, there aren’t really any other options:

  1. Virtually every civilization will go (or has gone) extinct before developing the ability to create these simulations.
  2. Virtually every civilization that has (or had) developed the ability to create simulations chooses not to do so.
  3. We are almost certainly living in a simulation.

Making Sense of the Argument

Most other articles on the subject brush over this explanation, but it’s important to understand.

If (1) is true, practically every civilization fails to live long enough to get to this post-human stage, and that means no one gets the chance to create these simulations. As Bostrom says, “Maybe there is some highly dangerous technology that every sufficiently advanced civilization develops, which destroys them. Let us hope this is not the case.”

Old History War Helicopters
Image Credit: manhhal via Flickr


If (1) is false, however, then a good number of civilizations will survive to be able to create these kind of simulations.

But just because they could create these simulations, it doesn’t mean that they would. Perhaps none of these civilizations would have individuals wealthy enough to run such experiments. Maybe all civilizations would see such simulations as immoral. But is that really feasible?

We’re already building rudimentary simulations Interesting World Simulations For Predicting The Future & Understanding Society Lots of people are very concerned about issues that affect their local communities, and maybe even their country, but are you the kind of person that's actually also very concerned about the entire world itself?... Read More . We’re already trying to map the human brain. Many historians would love the chance to run an ancestor simulation. In that sense, what are the chances that every civilization would always avoid creating these simulations? (2) seems pretty slim, I’d say.

That leads us to statement (3), which is by far the most interesting.


If one of these civilizations is able and willing to create a simulation, they would probably run many versions of it. And if one civilization is running these simulations, chances are other civilizations will run them, too. Perhaps simulated people would also start creating their own simulations, and so on. Very quickly the number of conscious people inside of simulations would vastly exceed the number of people outside of a simulation.

By default, this makes the probability of me and you being in a simulation much higher than the probability of being in base reality.

And that’s the crux of the argument. If some advanced civilizations developed the ability to create simulations, and actually ran them, we are statistically more likely to be in one of those simulations than not.

If in the future there are more digital people living in simulated environments than there are today, then what is to say we are not part of that already? — Rich Terrile, NASA Scientist

What Are the Chances?

It’s widely accepted that the Simulation Argument as described above is pretty water-tight. But that doesn’t mean we know which of the three statements is true. There is no real evidence for any of them.

Dice Probabilities
Image Credit: David Lofink via Flickr

Speaking of his own argument, Bostrom thinks that the chances are pretty equal between the three statements. Another renowned Philosopher, David Chalmers, puts the odds of us living in a simulated world at 20%.

One the other hand, Elon Musk thinks the odds of us living in the “real world” — base reality — are less than one in a billion. And NASA scientist Rich Terrile says it is “extraordinarily unlikely” that we aren’t living in a simulated world.

What Are the Implications?

Imagine that somehow we discovered that we were living in a simulated world. Bostrom believes that this shouldn’t change our lives too much. We can continue to learn about our (simulated) world through scientific investigation. Our feelings and experiences will largely remain the same.

Man With a PANIC Sign
Image Credit: Jim Kelly via Flickr

But there would be an undertone to our lives that would change. We would now have a secular version of a “creator”, and we could start trying to understand the “motives of the simulators”. We would have a different understanding of our place in the world — just like what happened when Copernicus discovered that the Earth was not the center of the universe.

An element of hope would be introduced. We could at last have the scientific possibility of an afterlife. Perhaps in death, we could continue our life in a new simulation (as was the premise of a Black Mirror episode).

Where to Go From Here

The simulation argument is little more than a philosophical thought experiment that’s managed to capture people’s attention. But whichever side of the fence you fall on depends on which of those statements you feel is most likely to be true.

No matter which you decide on though, there’s very little we can do about it. Whether that’s a good thing or a bad thing is open to debate.

Yet if the time ever comes for us to turn on our own simulation, thereby creating conscious, simulated people who do not know they are simulated, we have instantly shown (1) and (2) to be false. This leaves (3) to be the only option: that we are almost certainly in a simulation, too.

What do you think? Are thought experiments like this a waste of time, or is this argument actually on to something?

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  1. Marshall
    July 15, 2017 at 1:24 pm

    The argument depends on there actually being a large number of life forms developing into civilizations and progressing technologically. The problem is that intelligence may be just a human vanity. We have it so it must be good. I don't believe there is any good evidence that intelligence is useful to species survival and there is mounting evidence that it may be detrimental. Simply looking at our own planet, how much "intelligence" do the most long lasting species exhibit? Simple is better for species survival.

  2. Jouni "rautamiekka" Järvinen
    January 22, 2017 at 8:20 pm

    While it's possible to run the universe in a simulation (at least with our tech) while it's extremely taxing, running 7-7.48 billion unique full human brains is, at least with the tech we can use, impossible, we can't even run a rat's brain, which is very much like human brain, for too long on a computer bordering the slowest supercomputer.

    • Marshall
      July 15, 2017 at 1:27 pm

      I think the computer would actually only have to simulate the world of the observer.

      • Jouni "rautamiekka" Järvinen
        July 16, 2017 at 10:05 pm

        Can you elaborate on that ?

        • Marshall
          July 16, 2017 at 11:10 pm

          I guess I was thinking the the life form, or AI, running the simulation would only need what their observer could experience at any given time to be active. For instance, if they were in New York none of the Hong Kong simulation would need to be running concurrently. The equations defining Hong Kong would probably be activated by the simulated proximity of the observer and the New York equations would become inactive until needed again. I have no idea how a superior intelligence would do it, obviously, but that is how I would have approached the problem - but maybe I'm just programmed that way. ;-)

        • Jouni "rautamiekka" Järvinen
          July 16, 2017 at 11:18 pm

          Ya, it depends on the things that need to concurrently happen around the world, so of course Hong Kong wouldn't get full simulation attention when you're in New York but will some, assuming the concurrent simulation is necessary.

          Server Softwares use multithreading anyway, so an universe simulation would have to be extremely multithreaded.

        • Rob Nightingale
          July 29, 2017 at 1:04 pm

          In this case, assuming the observer is not the only existing entity, this solipsistic simulation would have to be run billions of times simultaneously. I'm not sure if that would require more or less computing power.

        • Jouni "rautamiekka" Järvinen
          July 29, 2017 at 3:51 pm

          Fallout 3 and the like are a good example of running an entire world (technically only a limited area in an entire world, like Fallout 3's main map having a limited cubic meter space) which could support multiplayer since the world runs as the same one thing for every entity (every entity sees the same without having their own simulation).

          Doing it that way allows to add, remove and modify content without doing much rewriting, but games running any sorta realistic worlds are extremely prone to bugs, which is why most games are left varyingly horribly buggy.

          The difference being those games don't execute the whole damn world all at once since it'd take far too much computation, not to mention memory, and it'd at some point become unfair and impossible for the player; circumstances related to things would had gone by, like a zombie assault on some base would had already happened, the defenders could have been killed, and stuff.

          For that reason the world has a -very- limited AI by itself, and the NPCs have a very limited arsenal of things they're allowed to do in the name of realism, which in turn limits how much the computer has to process the world and spend memory on.

          Maybe later when the game engines get more sophisticated and the computers get better there might be games that run much like the real world and as things happen you can no longer do some things the same way or at all but the game will make new things based on things. It's possible, but oh the amount of work to write all that manually !

      • Chris
        May 22, 2018 at 8:17 pm

        And what is to say that I’m not the ONLY one being simulated and everything else I’m seeing is a simulation, including twitter, facebook, etc.

        In that case, all your comments are simulations and none of you exist, apart from as comments on this blog.

  3. Tim
    November 27, 2016 at 7:09 pm

    Assuming the hypothesis that we are in/part of a simulation is correct without trying to prove it allows for some interesting ideas.
    Does this allow us to explain the "human condition" as a piece of corrupt programming? Or possibly it is a line of code that exists to limit the simulation's growth...Could that mean that the truly exceptional people that have come and gone, such as Ghandi, Buddha, Mohammed, Jesus Christ, Mother Theresa, Einstein, Newton, etc. were either messengers sent by the programmer to attempt to correct bad programming, or possibly "help programs" that were written in the original program to allow the simulation to progress and grow.
    What if, instead of being a first gen simulation, our "reality" is in fact a 5th, 20th, or even a 1100th gen simulation written within a preceding simulation....would that mean we are a simulation coded by a 10 yr old. as a science experiment...and quite possibly a failed one?!?!

    The possibilities of this thought of our reality actually being a simulation being true are quite interesting...

    It would allow for several of life's great mysteries to possibly be explained in simple terms;
    What was there before the Big Bang?
    Nothing, as that is when the simulation began
    Why can't we find other forms of intelligent life in the universe?
    This simulation doesn't contain code for that scenario, or we haven't reached that line of code yet

    And, without providing an excuse for people's ability to treat our world, animals, and each other like shit, maybe just maybe, thats the way the program is supposed to run.....

    Makes you think doesn't it....

    • Rob Nightingale
      December 15, 2016 at 10:28 am

      Completely agree, Tim! It's likely impossible to prove either way (much like any origination story), but as a thought experiment, what it leads you to is fascinating!

  4. Andrew Campbell
    November 26, 2016 at 2:35 pm

    Isn't that what most people believe: that the universe is too complex to have happened by itself? --But then why is it usually more acceptable to believe God pre-exists the Universe than for to believe the Universe to pre-exists God? --We tend to be egocentric, for psychological reasons we can identify better with a focused and particular God than the vast and complex, existing-all-at-once, Universe itself!

    • Rob Nightingale
      December 15, 2016 at 10:26 am

      I don't think the argument is trying to necessarily posit a creator. It's just taking an honest look at a few options we have to consider when it comes to the idea of simulated realities.

  5. Leon
    November 26, 2016 at 1:24 pm

    To Mr. Elon Musk...:

  6. Richard
    November 24, 2016 at 6:14 am

    It's almost laughable that someone can be certain by a billion to one odds that our consciousness is a computer simulation. Especially when scientists still do not have a clue how consciousness is created within the biological cells of the brain. In fact there isn't even a theory of how it "might" happen. Brain cells utilize parallel processing, computers utilize simple serial processing. The brain also has thousands of different types of neuron cells, communicating with both electrical and chemical means in a parallel fashion. Recently scientists have discovered that brain cells also seem to communicate with photons. And here is someone claiming he's certain this unimaginably complex process can be duplicated with silicone transistors running on electricity.

    • Rob Nightingale
      December 15, 2016 at 10:25 am

      If you read Bostrom's original paper, he goes into a lot of detail about why we should assume that consciousness needn't be limited to organic matter. And Musk's "one in billions" claim is more just a matter of observation. He believes that it's likely other civilizations could, and have, made these kind of simulations. In which case, there could be one trillion simulated people in the universe. Via the laws of probability (not faith or belief), the chance that we are one of those people who are in base reality is one in billions.

  7. Theory
    November 24, 2016 at 3:45 am

    I feel as if this argument is on to something. It's a theory that will prove itself to be true or false but only over time. That being said, I don't think much thought should be put into it. I think we should continue making making advancements to technology and let Science take its course.

    • SS Reddy
      November 24, 2016 at 8:29 am

      Nice reply. Just enjoy the moment and not think too much into future.

    • Rob Nightingale
      December 15, 2016 at 10:22 am

      Completely agree. Whichever hypothesis is true, there's pretty much nothing we can do about it.