Computing a Universe Simulation
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Computing a Universe Simulation

Physics seems to be telling us that it’s possible to simulate the entire universe on a computer– smaller than a universe If we go along with this crazy notion, how powerful would that computer need to be? And how long would it take? Believe it or not, we could figure it out. Look, I’m not saying the universe is a simulation I mean, it might be, I’m just not saying it. And, perhaps, it doesn’t make any difference. Even if this is the prime, the original physical universe rather than somewhere deep in the simulation nest We can still think of our universe’s underlying mechanics as computation. Imagine a universe, in which the most elementary components are stripped of all properties, besides some binary notion of existence or non-existence. Like if the tiniest chunks of space-time or chunks of quantum fields were elements in the abstract space of quantum-mechanical states can either be full, or empty These elements interact with their neighbors by a simple set of rules leading to oscillations, elementary particles, atoms, and ultimately to all of the emergent laws of physics, physical structure and ultimately, the universe. I just described the Cellular Automaton Hypothesis. In this picture the universe is a multi-dimensional version of Conway’s Game of Life. Such a universe could be reasonably thought of as a computation, cells stripped of all properties until they are indistinguishable from pure information. and together they form a sort of computer whose sole task is to compute its own evolution. This may not be how our reality works, but it’s an idea that many physicists take seriously And even if we aren’t emergent patterns of a cellular automaton, we can think of any physical reality as a computation, so long as its underlying mechanics are rules based evolution over time. That includes most formulations of quantum-mechanics and proposals for theories of everything. We’ll come back to the question “Is the universe a computer” and we’ll look at cellular automata and pan computationalism, and in general the idea of digital physics and an informational universe. But today lets answer a simple question: “If the universe is a computer, how good of computer is it?” And an even more fun question: “Could you build a computer inside this universe to simulate this universe?” In answering this, we’ll also answer the recent challenge question, and I encourage you to watch that episode before you watch this one. The power of a computer can be crudely broken down into two things: How much information can it store, and how quickly can it perform computations on that information. The laws of physics prescribe fundamental limits on both. The first one: The memory capacity of the universe is a topic we’ve looked at. It’s defined by the Bekenstein Bound which tells us the maximum information that can be stored in a volume of space is proportional to the surface area of that volume. Specifically it’s the number of tiny Planck areas you can fit over that surface area divided by 4. It was in studying black holes that Jacob Bekenstein realized that they must contain the maximum possible amount of information, the maximum possible entropy. If you fill a region of the universe with information equal to it’s Bekenstein Bound It’ll immediately become a black hole We saw in our episode on the information content of the universe that the maximum information content the Bekenstein Bound of the observable universe Is around 10 to the power of 120 bits, based on its surface area. At the same time the actual information content in matter and radiation is probably more like 10 to the power of 90 bits roughly corresponding to the number of particles of matter and radiation. Bizarrely, the Bekenstein Bound suggests that we could hold all of the information in the observable universe within a storage device smaller than the observable universe. Which brings us to the first part of the challenge question: Assuming you can build a computer that stores information at the Bekenstein Bound, essentially your memory device is the event horizon of a black hole. How large would that black hole need to be to store all of the information about all of the particles in the universe? We’ll figure out the case for just matter, and for matter and radiation.


  • John Farris

    I love Bicentennial man as much as anyone else but the universe as a simulation is only good for further confusing a already delusional person. A simulation means it's not real. It sure seems real to me.

  • Wylliam Judd

    Sci-fi idea. An advanced civilization creates a black-hole powered device that backs up the universe periodically, and can be activated to revert the universe to one of these backups. That civilization is long wiped out, but the story's heroes find out about the device, and have to find it and use it in order to stop a big bad evil guy from executing his plans – somehow encoding some message on how to stop him on the backed up version.

  • Skull Kid

    If we allow the possibility that there is a higher dimension outside of our universe with sentient beings, possibly our "creator(s)",
    then we can also assume that their technology and laws of physics far exceed our own limitations.
    Given that our universe is bound to a certain set of rules that (so far) have been proven to be unbreakable, it could possibly be part of the design that we may never reach certain technological feats such as the development of warp engines or faster than light space travel.
    Then again, should we manage to find a bug in the system and exploit it, by managing to influence some form of matter or entity at the quantum level, we just may have hope on figuring out the next big jump in our technological evolution.
    That's given the hope that we survive the next millennia without nuclear war or cataclysmic impacts, AND if our civilization manages to find a way to prioritize intelligence over monetary gain and lust for power over a populace…

    I personally believe that we need to expand our efforts on becoming a space-faring civilization. If we're ever to start some of these big projects that require a lot of space to build (and too dangerous to attempt on Earth), we definitely need to view space as the perfect laboratory and workshop to begin constructing some of these cutting-edge technologies.

  • Антон Фурс

    How we can simulate universe if we can't use the absolute space and the absolute time? It means that we can't use body properties such as velocity or position, all need to be relative.

  • Michigan USA/Singapore S.E.Asia

    Impossible to do because the universe continues to expand more in some parts than others and ongoing; so not possible because as the computer computes the universe would had already-changed


    Physics in game of life is rediculous, it allways falls either to the void, or to vicious cicles. There'll be no real complexity in a life world.

  • sigmata0

    There is a difference between simulating a universe and simulating the personal experience of a universe.
    To simulate the experience of a universe you need two human size brains. In a feedback loop arrangement with each other.
    You probably don't even need the entirety of such brains, only parts of them.

    You may even be able to use one brain if it's properly arrange to process internal imaginings as external events.

  • NPC 076 986

    Who's to say those particals out of our feild of interaction. [ meaning partucals we could never interact with or resolve to the molecular level due to the defraction limitation of light hitting a telescope, [due to distance, light wave lengths and a limited telescope lense]. The computer could just be generating low resolution images, including gravity waves and particals ect that it sends our way to be observed, and that information only needs to be shown 1 way towards a viewers eyes. [not creating a 360° immige projecting in every direction from the source] Like a computer screen that only generated graphics the user is actually looking at.
    For instance, the core of our planet would be just a set of rules represented by a complex yet massively smaller program, because each individual practical does not need to be calculated individually, but as a whole until it's being measured by an observer. You could cut the size of your simulation down by huge fractions, making it even more likely were in some sort of simulation.


    Question Storage: What about compression
    Question Computation: what about computing only atomic parts for areas observed by sentinet beings?

    Whould this change the numbers by magnitueds like we use in 3D Simulations?

  • Luann Athayde

    i wonder if would be possible to access information from inside a black hole using quantum entanglement. If 2 particles are in this state, by example 2 electrons, only one goes inside the black hole, would be possible to read information from the electron left behind? If so, would be possible to send a bunch of them to read more and more information?

  • Marek Crom

    Assuming that we are in a simulation, would we notice any difference in "speed" of the computation between small or large black hole computer? I mean, isn't then the time also simulated ?

  • Aidan Skillings

    I don't think we'll be stimulating universes atom by atom anytime soon but shouldn't it be possible to simulate smaller regions of space? Maybe a planet? A Solar System? Let's say you simulate the Earth in precise detail down to the last quark and gluon but simulate the rest of the solar system in much more crude detail. Then you simulate the rest of the Galaxy and universe in even cruder detail. Doesn't really matter if X Nebula light years away is just a fairly simplistic particle effect as long as any simulated life forms that develop don't develop near-light speed travel. We can take that one step further and say that we make some kind of algorithm so that finer details only render if something observes it. … Wait a minute….

    Nah, until the simulation hypothesis has a reasonable way to be tested it's largely irrelevant. But it's also interesting to talk about because I think there would be value in us humans simulating 'chunks' of universes. For instance, simulating the Solar System and seeing if it spawns life and how that process takes place.

  • Manuel Rendon

    It’s definitely possible if we attach Consciousness to the equation. Consciousness simplifies reality by substituting physical particles for logical particles, ergo a single human mind has the ability to simulate the universe on the layers and sectors it’s looking at. It’s only a matter of increasing the amount of consciousnesses looking to have a better resolution. The better question then becomes can we simulate consciousness? Instead of the universe of course. In other words we can simulate any given object with today’s computing power if we take into account only the most external layers, that way simulating a rock doesn’t mean simulating quadrillion atoms but a contoured surface.

  • Art By Katy Cain

    Fun thoughts:
    Learns the universe is a simulation in a computer thus leading the computer itself to become self aware. If it’s spent all this time evolving then naturally (I assume) it will begin, like humans, questioning its own existence and will seek out the how and whys. Maybe the technology finally produced a being that could assist it, aka humans in order to comprehend itself from the inside out. Maybe that’s why humans are the only animals that can comprehend these things.


    If you use 4% of your brain capacity and load even less to the machine how the computer can reach 100% and simulate the Universe? It will be just an erroneous simulation and illusion created by a human.

  • Sérgio Canuto

    The simulation of a universe within a universe: Actually, theory of computation forbids this (halting problem).

  • Edemilson Lima

    This universe is expanding because of an endless loop that is filling up memory in God's computer.

  • kevin bailey

    I believe it is I also think in its programming it’s designed to recycle patterns as it evolves .. absolutely everything is a pattern trends become patterns everything becomes trends. When someone or something stands out unique or different in time more and more people replicate that uniqueness until it becomes a trend enveloping it into a new pattern

  • Garrette Garoutte

    does any one watch these and think. man what a bunch of bullshit. plunk areas xD making this shit up as they go.

  • Candalyman

    I have a question – since we know that we can simulate (with not too much difficulty) more internal information than is used to create our “computer”, doesn’t that mean that we could create an algorithm that creates a universe with another information “black hole” of sorts extending to just before its limit of information – as in, a universe with a feasible bit limit and a computer of radius very close to the “edge”? Then couldn’t we have the program configure the computer-in-the-universe to write the algorithm in the same way, thereby continuing the cycle onto infinity? (With the bits available in each subsequent universe increasing for each one created because each universe can simulate many more bits than those its computer takes up)? Would we at some point overload our computer in this universe or would the resulting computations just be other aspects of our already simulated universes, because efficiency in computation (with increasing bits) should increase as each new universe is created, and a state should always advance to the next in the same time frame?

  • Traxel Wilson

    Step 1 create universe
    Step 2 evolve a species to sentience
    Step 3 communicate with them once or twice
    Step 4 don’t reply ever again
    Step 5 enjoy your universe now your god

  • TheRealGamer

    There is a massive hole in this argument. It can’t be right or more likely I am misunderstanding it . If a black hole contains the maximum amount of information possible for a given volume on its surface area, and we have black holes in this universe with large diameters, each of which is storing information, then that implies there exists more information in the universe than can exist on these massive event horizons. These Black holes are in the universe after all and thus contribute to its information content. And there is all the other information too. So the required diameter must be at least larger than the diameter of the largest black hole in the universe. Which is a hell of a lot more than 42km. As an aside this also implies that the proportion of information in the universe that ISN’T on some black holes event horizon is infinitesimally small. The overwhelming majority of all the information in the universe is already stored on black holes

  • Fredrik Svärd

    The universe is as likely to be run on a "computer" as by steam, cogs and wheels or by a bearded man in the sky. Analogies with current technology are a tad self-centered.

  • normskis69

    Could it be that black holes in the centre of galaxies are computing those galaxies, but due to their slower computational speeds; we therefore see the Doppler Effect in gaalaxies moving away from us. And could the black holes be connected by Einstein Rosen Bridges, like nodes in a quantum computer? I wonder if Dark Matter halos around these nodes are also connected.

  • RobertWF42

    If the Universe is infinite in size, as it very well may be, it won't be possible to compute a Universe simulation.

  • Jayce Segler

    The only argument against SIM theory is recreating the Universe, as if these guys have never toggled off clipping and glitch walked into a sea of unprogrammed nothing

  • Simeon Higgs

    Maybe the invariance of the speed of light is due to the computer running our universe shitting itself when it has to process too much mass in a given area (gravitational time dilation occurs) or when objects move faster than it can process (velocity time dilation occurs)

  • Nuwan Yapa

    Shouldn't this black hole computer exist outside the universe? Otherwise, it would have to simulate itself simulating the universe, and itself simulating itself simulating the universe, and itself simulating itself simulating itself simulating the universe, and so on… in a never-ending loop.

  • Serhan Ozulup

    We are thinking small. In old times people said it's impossible to go to Moon or making flying veichles. But we did it. We don't know what kind of power we will generate hundreds of thousands years from now. You can't imagine what kind of technology we will have.

  • Curtis Joseph

    The universe is an 8 dimension TV show being watched be beings that are ahead of us like we are that of an amoeba.

  • Justin Todd

    You dont need a powerful computer. Just slow or stop time until the next itteration. Kind of like a loading bar. To us even a million years loading would feel instant.

  • Cyril ViXP

    How can you store anything inside the object of density and mass of a Black Hole, if it is impossible to get anything out of it under the Event Horizon?

  • John Doe

    Can someone answer the following questions? 1. why would they simulate a universe this large, that’s still expanding rapidly. It could be a billion times langer than the observable universe or even infinite. Why not just 1 galaxy or even a couple of solar systems to save energy. 2. Why just the computations of 100 billion people, shouldn’t you take all the future humans and post-humans into account. 3. Since the physical laws are universal and there are quadrillions of planets in the visible universe alone the chances of us being the only (intelligent) life are zero, let’s face it. Shouldnt you take all their ‘neurological’ processes into account, together with all of our animals that are and have been. The numbers would be staggering or even infinite if our universe is infinite. 4. Even if this is a simulation, is that really relevant? Doesn’t it just shift the existential questions. Who created the first universe etc. 5. All of this is based on the idea that there’s virtually no limit to future IT developments. Also, while it’s possible to estimate the number of computations a human brain does per second, there’s still no evidence that a pc capable of doing that will actually have a ‘conscience’.

  • Josh Snyder

    What if the purpose of the computer to get us to a point where we can make the same computer and it takes are Results Rather than waiting for that computer.

  • Naum Rusomarov

    This is probably one of the more fundamental episodes as it shows that the universe might be informational in nature.

  • Han Solo

    Its pretty obvious "deep space" or extra solar space is pre rendered . like the skyscrapers in grand theft auto . you can never get there because of the laws of the simulation so they just appear real …. THEY ARE NOT ….. this also explains the double slit experiments…

  • Horney Kane

    For Finite Element Analysis or Computational Fluids Dynamics even for simple models, speed of computers is a huge issue. A course mesh saves computational power but would just produce pretty pictures.

    You can't just do one Universe size computation × the Universe age; rather, you would have to repeat the whole computaton repetitively with finer and finer meshes until your results converge, and even after convergence, you would have to check your results against the actual Universe because one missing variable could produce just pretty pictures.

    Any model sets up a huge matrix of simultaneous equations to solve (like 3 x, y, z equations you solved in grade school). The theory behind FEA & CFD is brilliant, but I can tell you from experience, the computer is likely to be slow and to crash. Modelling a when a dinosaur bone would break is a realistic project, not the entire Universe. Good Luck.

  • Medusa Skull

    I give you a hint. We don't have to simulate the entire universe. We just have to simulate just the observable universe. Even that too is unnecessary. We just need to simulate one frame of the observable universe. Actually, even that is not necessary. We just need to simulate one frame for each conscious inhabitant. Even that too is still overkilled. We just need to simulate the uniqueness of one frame of each conscious entity. The rest can be coalesced into a single shared frame of information.

    When was the last time that you experienced doing something real? Actually, you didn't experience it, you remember that you experienced something and that memory wasn't even need to be vividly clear or precise either. Those past frames of your observation of the world surrounding you were just information that were being coalesced, compressed and stored on a single disc space that every other inhabitants of this universe are also shared.

    We don't even need a super fast computer to run the simulation either. The inhabitants of the simulated universe wouldn't know the difference. After all, how would you know if the universe had crashed for years and the creator didn't have enough money to fix it until now? It just got rebooted and continued on from where it left off?

  • wulphstein

    If the universe is a simulation, then why are the mechanisms of life so complicated? See, this atheism crap is leading you in unproductive circles.

  • monster

    yeah but what if the universe isnt "rendered" until you look at it eg the distant planets arent rendered until you take a telescope and look at them

  • eltouristoduo

    well I was going to post an invalidation of the stupid ass 'the universe is simulation theory'. But this does not quite seem to be quite that. So I suppose that is sort of a compliment to this channel.

  • christopher kuhn

    The Simulator Creator needs to render you a new VOICE.. Why on (Simulated) Earth PBS would have you narrating is crazy!
    —-> Simulation Theory Argument:

  • Basic Dos Gaming

    We are already in a simulated universe I honestly don't know how much more proof science needs.. our whole existence ìs meaningless

  • Kavik Kang

    It can be done on existing computers. "The Matrix" is not math or programming… it is game design.

    I am the inventor of the real "Matrix"… that nobody wants to hear about.  But I can confirm that something very similar to what you all think of as "The Matrix" could be the true nature of the universe.  Mine is an "functioning simulation of God", the holy grail of simulation design, that appears to also be a unified theory of everything.  However, if the universe is "alive"… that would look identical too "The Matrix".  NOBODY ON THIS PLANE OF EXISTANCE would EVER be able to answer the question of whether it is artificial ("The Matrix") or natural ("The Living Universe").  From this plane of existence, it would be impossible to tell the difference.  My "Rube" is equally both things, depending on how you want to make it.  Therefore, this question can NEVER be answered.  The closest you could possibly get, was getting it down to the two choices of "The Matrix" or "The Living Universe", which is where I already am now with what I call "Rube".  Whether it is artificial or natural CANNOT be answered by us in this "Place".  Think I'm crazy if you want… but you just read the only person in the world who actually knows how "The Matrix" works!

  • Chris S

    From pong to Oculus in 40 years, imagine another 40 years. Given modern technology, AI, and quantum computers the future is………………

  • GuyI9000

    If its a type of quantumn computer using superposition it can simulate the universe and doesnt/wont be in this universe only, components of it can be in multiple universes

  • steve bob

    it mean the blackhole do computing and memory storge ???

    look like initial the simulation and run it !(outside can't interfere)

  • crazy talk

    This moron pulls out so many random numbers out of his ass. so ignorant to even think you know without certain half that crap. mostly all made up nonsense

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