Why it is (nearly) impossible that we live in a simulation

Just keep reading the abstract.

> Only universes with very different physical properties can produce some version of this Universe as a simulation. On the other hand, our results show that it is just impossible that this Universe is simulated by a universe sharing the same properties, regardless of technological advancements of the far future.

One strand of argument for the simulation hypothesis is that future beings would conduct "ancestor simulations" to understand key events in history. Such simulations would of course use the same laws of physics (or nearly the same) to be useful. This paper, at least, refutes the ancestor simulation strand of arguments (to the extent you believe it of course)

Who knows, it could be populated entirely by all-knowing, all-powerful beings that watch our every moral decision and intervene in subtle ways if we sincerely entreat them.

The simulation argument is that we'll make these universe simulators. Because we will in this universe, they'll be common. If they are common it's likely we're in one.

If you change that to they won't happen in this universe. That suggests they are not common. And so while we could be in a simulation the argument kind of dies off

I present to you the halting problem.

I love this. It seems like conspiracy theory on a Universal scale.

And at that point it doesn't matter if we're in a simulation as it could be simulations all the way down.

Just pointing out that that is the case for Christianity too (not religion in general because others that I am aware of require some sort of actions be taken, although some would say that true acceptance necessarily leads to actions so there is room for debate there). Also, if the creator of the simulation did want to guide us in a specific direction, might they send avatars into the simulation with messages, rather than simply banking on individuals like yourself to come up with the “goal” on their own? I’m not coyly suggesting you must convert, just raising some thoughts that I’ve had.

This sounds like Pascal's Mugging.

Because how can you account for those undiscovered phenomena? You can only imagine them, but then you stop making science and start writing sci-fi

Because science is made up of humans and humans like to make dramatic conclusions, because those seem to be more likely to result in attention and promotions and prestige.

It's not a weakness limited to science, believe me...

Mankind didn't know about germs, black holes, electrons, radioactivity, … for a long time but back then no one ever claimed they didn't exist, either. They were simply outside our realm of experience but at the same time there was also nothing in our experience as humans that was really constraining their existence.

Today, we have a pretty good understanding of the broad strokes of how nature works (think local energy & momentum, spacetime, quantum mechanics, etc.) Yes, we don't understand everything yet (not by a long shot) but we expect future insights do be compatible with what we've seen and measured so far[0]. In that sense, today's "laws" of nature constrain tomorrow's (updated) "laws" of nature. This is also how the authors arrives at his conclusions.

[0]: Yes, there is no guarantee for that. It could happen that physical laws change wildly from one day to the next. But this is not a particularly interesting direction for a research program, because if you start with that assumption, then anything could happen at any time, and physics as the discipline of trying to understand nature would become a rather pointless endeavor. However, the success of physics at describing nature seems to indicate that we're onto something.

I think you misunderstand what science is and how it works. Everyone understands that we are not just possibly, but in fact certainly, missing not just one something but many things. But until there is actual evidence of those things, they can't be considered.

Nobody thinks that science as it stands now is complete or even necessarily correct. All scientific knowledge is always provisional, subject to revision as evidence requires.

They could just append "according to current scientific knowledge" to every sentence. But it would be a waste of time.

I think you're being profoundly uncharitable in that characterization of the author's work here, in that if you read the paper (and, really, even just the abstract), you'll see that they clearly understand the existence of such possibilities, and have simply chosen to limit their investigation to what their area of professional expertise (namely, the physical sciences) can assess with confidence. An illustrative quote from the concluding discussion:

Guessing how conservation laws for energy and information applies in a universe with entirely different laws, or whether they should even apply in the first place, appears impossible and this entirely prevents us from guessing whether the SH is possible in such case. For example, hypothetical conscious creatures in the famous Pac-Man video game in the ’80s will just be incapable of figuring out the constraints on the universe in which their reality is being simulated, even based on all the information they can gather around them. They would not guess the existence of gravity, for example, they would probably measure energy costs in ”Power Pellets”, and they would not conceive the existence of a third dimension, or of an expanding space time, and so on. Even if they could ever realise the level of graininess of their reality, and make the correct hypothesis of being living in a simulation, they would never guess how the real universe (”our” Universe, if it is real indeed) function in a physical sense. In this respect, our modelling shows that the SH can be reasonably well tested only with respect to universes which are at least playing according to the Physics play book - while everything else appears beyond the bounds of falsifiability and even theoretical speculation.

If you were simulating two beings' experiences of the universe and they met and compared notes, you might expect little incongruities where random chance was used in the decisions necessary to generate their perspectives.

Let's say a sparrow falls and a simulated being observes it, but so does a camera, which stores the footage in an unexamined hard drive. Years later another being observes the footage stored by that camera, and up until that point there had been no point in manifesting it in the simulation. Would the wings of the falling sparrow flutter exactly the same way for the two observers? What if they met and discussed it, as part of a deliberate experiment to test the consistency of the universe? Would they agree? Imagine the computational overhead necessary in storing details that you're not sure will ever be useful. The same logic could hold true for a photon generated by an exploding star 12 billion years ago that zipped across the expanding universe and eventually interacted with some silicon in a CCD in an astronomer's camera.

Indeed, you only have to simulate what one person perceives and where they explore, etc. One person's conscious experience in theory should be able to be fully simulated with very little information relative to the complexity of matter etc. You just have to simulate the senses and model the universe around a person.

And why not do that as an experiment? If science/experimentation is a useful thing - why not have the main reality and lots of individual experiments?

> However, since we have NOT created such a simulation, we are either in the FIRST real existence, OR the last in line of simulations which have not yet created one. So the chance go down from infinite to 1 that we ARE in one, to 50-50 that we are NOT.

This is like saying that the chance of winning the lottery is 50%: Either you win or you lose. I hope further explanation of why this is incorrect is not necessary.

Obligatory.

https://www.youtube.com/watch?v=1kKoqE-sAb8

And that the number of observers in this universe will be allowed to grow infinitely.

It's entirely possible that the universe will conspire to have some clever mechanism to limit the number of observers to whatever the universe simulation can support. For all we know They have been upgrading the cluster as we advance. We don't even have a way to know if the simulation is in real time. Maybe it slows down when we have too many babies or make too many sensors, and speeds up after a plague.

But whatever the truth is, the game is whatever winning conditions you wish to make it. Some people have very personal goals, others subscribe to group goals. We don't know if there's an after.

Even when someone else gives your life meaning, you still chose to accept it. Most of us reject when someone tries to give our lives a negative meaning. That door swings both ways.

In this era perhaps it's a plus. The paper is the direct thoughts of the authors, and hasn't been put through a LLM.

Any part of the universe you look at requires simuilating too much of the entire universe to get it from the state you last observed to the state it's supposed to be in now.

Time is important, if it takes too long no one is going to run the simulation.

The entire point of the simulation argument is they are fast and easy and therefore common. If simulations are common then it's likely we're in one. If you keep adding requirements that likely make them slow and hard then they are likely uncommon and the argument for us being in one disappears.

I thought chaos doesn't allow that kind of selective simulation, although maybe no one would notice that the butterfly effect only happens in places people are watching.

Ken MacLeod used a similar argument in The Corporation Wars.

Isn't it not really deterministic because you cannot know both the exact position and exact velocity of particle? (along with the other pairs of physical properties that also follow the uncertainty principle)

> So, any smart simulation would only be simulating a small very percentage of itself at any given time

does a falling tree make a sound if the simulation is not running? : )

Yeah, when I heard that the largest supercomputer in the world was going to simulate the folding of a single protein (something that takes infinitesimal time and energy in reality) it was also obvious to me that simulating the universe would be incredibly wasteful. There's plenty of room at the bottom but not that much room.

Of course this argument does not apply if the outer universe contains extra dimensions or whatever, but that isn't the kind of ancestor simulation Bostrom and friends are talking about.