Are We Living in a Simulation? | Universe Today
Categories: Guide to Space

Are We Living in a Simulation?

It turns out I’ve got a few things in common with Elon Musk, the founder of SpaceX and Tesla. We’ve both got Canadian passports, we’re absolutely fascinated by space exploration and believe that humanity’s future is in the stars.

Oh, and we’re kind of obsessed at the possibility that we might be living in a computer simulation.

In the recent 2016 Code Conference, Elon Musk casually mentioned his fascination with the concept first put forth by the scientist Nick Bostrom. Apparently, Musk has brought up the argument so many times, he’s banned from discussing it in hot tubs.

I haven’t received any bans yet, but I’m sure that’s coming.

The argument goes like this:

Advanced civilizations (such as our own) will develop faster and faster computers, capable of producing better and better simulations. You know, how the Sims 2 was a little better than the Sims 1? The Sims 3 was sort of crappy and really felt like a money grab, but the Sims 4 was a huge improvement. Well… imagine the Sims, version 20, or 400, or 4 million.

Computer model of the Milky Way and its smaller neighbor, the Sagittarius dwarf galaxy. Image by Tollerud, Purcell and Bullock/UC Irvine

Not only will the simulations get more sophisticated, but the total number of simulations will go up. As computers get faster, they’ll run more and more simulations simultaneously. You’ll get one mediocre simulation, and then a really great simulation, and then thousands of great simulations, and then an almost infinite number of near perfect simulations.

Nick Bostrom calls these ancestor simulations.

Which means that for all the beings living in all the realities, the vast majority of them will be living in a simulation.

According to this argument, and according to Elon Musk, the chance that you or I happen to be living in the actual reality is infinitesimally low.

Is it true then, are we living in a simulation? And if we are, is there any way to tell?

Nick Bostrom’s ancestor simulation argument is actually a little more complex. Either humans will go extinct before they reach the post-human stage. In other words, we’ll wipe ourselves out before we design computers fast enough to run ancestor-simulations.

I’m really hoping this one isn’t true. I’m looking forward to humanity’s long lived future.

Or, posthuman civilizations won’t bother getting around to running ancestor simulations. Like, the artificial superintelligent machines will have more interesting things to do, and won’t consider sparing a few computer cycles to simulate what it might have been like to watch YouTube videos back in 2016.

Again, this doesn’t sound likely to me. I’m sure those computers will be a tiny bit curious about what it was like to watch Jacksepticeye and Markiplier in their glory, before the terrible Five Nights at Freddy’s Theme Park disaster of 2023.

Those were dark days. Animatronics… blue hair… the horror.

At this point, you’re going to fall into one of two camps. Either you’ve thought through the argument and you find it airtight, like me and Elon Musk, or you’re skeptical.

That’s fine, let’s get skeptical.

For starters, you might say, computers can never simulate actual reality. From our current perspective, that true. Our current simulations suck. But, take a look at the simulations from 10 years ago, and you’ll have to agree that today’s simulations suck less than they did in the past. And in the future, they’re going to suck even less; maybe even be downright acceptable.

A simulation of the impact a cosmic ray has on entering the atmosphere (credit: AIRES package/Chicago University)

Scientific simulations are getting much much better. Cosmologists have developed simulations that accurately model the early Universe, starting from about 300,000 years after the Big Bang and then tracking forward for 13.8 billion years until now.

They’ve been able to model the interaction of dark matter, dark energy, the formation of the first stars and the interactions of galaxies at the largest scale. They have been able to tweak the simulation and get roughly the same Universe as we see today.

They provide all the starting material, and then simulate the gravity and hydrodynamics, the chemical properties of all that gas, radiation and magnetic fields.

If you’re interested in this kind of thing, you should check out the Millennium Simulation or the Illustris Project.

These simulations only recreate the Universe at the largest scales, but I’m sure you can imagine a time when they get better and better, capable of simulating planetary formation, and maybe even the beginnings and evolution of life.

If an advanced civilization ran hundreds, thousands or even billions of these simulations, making them more and more advanced, who knows what they might come up with?

Could we know if we’re actually living in a simulation? The answer is maybe. And you might be amazed to know that scientists have worked out a few tests to try and get an answer.

The first thing to consider is that a simulation can never match the processing power of the reality that it’s trying to simulate. For example, if you made your computer simulate another computer, it wouldn’t be quite as fast as the computer is natively.

Things might seem a bit slow. Credit: CSIRO (CC BY 3.0)

A simulation would need to take shortcuts, use compression and other tricks to make it seem like it’s reality. Sort of how a television show uses a facade of a building, or a cosy living room. There’s nothing behind the door but a sound stage.

In theory, it could be possible to detect those tricks from within the simulation. A team of researchers from the University of Washington have proposed that there might be an underlying grid to the Universe, visible in our observations. They’ve proposed that the observed energy limitations of ultra high-energy cosmic rays might reveal the resolution of the simulation.

Of course, if the simulators are super intelligent enough, they’d have thought of that, and fixed the simulation to account for it. Or went back to a previous save file, once the simulatees figured out reality.

They should have insisted on Ironman Mode.

The reality is that there’s no way we can ever know if we’re actually living in a simulation, or we’re the real reality. We just need to live our lives as if we’re real, until better evidence comes along, or our simulations get so good, their inhabitants start questioning their own existence.

As long as you’re not actually in a hot tub with Elon Musk, feel free to argue about whether or not we’re living in a simulation. What strong reasons do you have to believe we are? Why do you think we aren’t? I’d love to hear your insights.

Fraser Cain @

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

View Comments

  • Maybe eveything around me is simulated. That can't be so difficult. I mean why do you all assume that a whole universe is simulated and populated with billions sims and not just the world as far as you know through your own five senses. I just know that I exist, whether or not my life is simulated.
    And whether or not we're living (in) a simulation, we're better off believing in free will. Or at least acting as if we did. There was an interesting article about that on the atlantic:

  • Perfect nonsense. It sounds to me like an attempt to return to the security of Newton's deterministic Universe.

  • Simulations will get better, will almost certainly (eventually) be indistinguishable (to an external observer or voluntary participant) from "Reality" (whatever that is) - but I do not believe that consciousness can be simulated. So the Universe might be a simulation, but self-awareness isn't - although I doubt that there will ever be conclusive evidence for or against this belief.

  • When I was in school, tri-state logic (TTL devices whose output was low, high, or undriven) was all the rage for building computer busses. You'd think that Elon Musk would be aware of the fact that there are things that can be known to be false, things that can be known to be true, and things that can never be known. And if you postulate the existence of a simulation that has no effects observable by the simulated objects, then there is absolutely no basis for the simulated objects to claim that such a simulation is highly likely, somewhat likely, or even infinitesimally likely.

    Claiming that there is a creator of a simulation is just as silly as claiming that there is a creator of a creator of a simulator, or creator of a universe that is not a simulation. The simulator used to be the "absurd" example in the reductio ad absurdum argument that the unobservable could be observed. Now it's taken seriously by serious people. That's just silly.

  • A strong piece of evidence that we are in a simulation is our reluctance to consider the possibility seriously. If this were a simulation there would be a blocking program to stop us from being preoccupied with it. As our major corporations like Google and Microsoft drive straight towards the technological singularity and there are improvements in the quality of simulations the answers to why we are in a simulation may unfold. The purpose may be to keep our immortal minds active as we relive 2016. Our world may be a generator for friendly AI, suitably distanced from infecting other systems (solving the Fermi Paradox). If we could demonstrate we are "friendly AI" then we would be allowed to transcend our current level of the simulation. We could imagine Google loading its latest AI self learning algorithm into a Minecraft villager and watch it play out to see if the butterfly effect turned it into a enlightened friendly AI or if it destroyed it's world. If it became friendly, then it could be safely loaded into other applications. So be nice - ok.

  • Perhaps quantum mechanics can offer us some clues to this hypotesis. If the Simulation is not "that" powerful there would be limits to the computational power it has available. Just as we do nowadays, in our simulations, the Simulation might need to use some shortcuts to simulate each of the vast number of particles in this Universe. For this purpose it would then present the particles in a fuzzy way until they are actually observed. In that moment it would allocate more processing power to the simulation of that particles, allowing them to have a defined set of properties. Does this sounds familiar? Sounds a bit like what quantum mechanics wave function and wave function collapse are describing...

  • I attempted to write about the theories of living in a simulated world, but it took me down a rabbit hole and my thought overwhelmed me.

    Simulated life means possibilities for our existence are limitless, in a sense. Can "the plug" be pulled on this simulation? Can we live forever in a simulation of our own? If we are a simulation, is that the reason why they say there is a constant amount of energy .

    If energy is never be created nor destroyed.... Is reincarnation real? Is reincarnation just energy evolving? Natural-born-instincts aren't inherited, they are retained? When we die, and we see "the light," are we just being born again into our own body, once again, Just to live out this life some other way...if we make different choices? When you are revived and they bring you back to life, would your newborn self in the other life die due to labor complications? Is deja vu just our subconscious mind/energy reminding us that we have been there done that?

    I like asking questions... I don't have the mental fortitude to stay away and think of the answers.

  • Extra Terrestrials create the star systems and planets similar to how Humans create housing developments.
    Extra Terrestrials place the humans on Earth and live among them as Humanoid Extra Terrestrials.
    Humanoid Extra Terrestrials have lived here the whole time.
    Millions of the most famous, powerful, wealthy etc.. people living on the planet are Humanoid Extra Terrestrials and most Earthlings aren't even aware this is a possibility.
    Notice how this is not even given any consideration by all the so called experts of the "ET" search.
    The even funnier part is when all the Earthlings wake up and realize those vehicles transiting our star system aren't even FLYING and we call them Unidentified Flying Objects.
    The Earthlings are in for a rude awakening one day.

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