what do physicists mean when they say we potentially live in a simulation?

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I get what a simulation is, at least in the very literal sense. What I’m experiencing feels like reality, it would have to, it’s all any of us have ever known. But what would it mean for us if we truly lived in a simulation? Can it just be turned off and we cease to exist? If we found out we did live in one, how could it change our reality? How do we even hypothesize such a thing? I have zero background in physics just so we’re at an understanding of my physics understanding.

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Anonymous 0 Comments

It is a tought experiment, but everyone commenting seems to be missing two important things:

1. That doesn’t mean it’s not scientific. A lot of physics is “just a thought experiment” in this sense. Take dark matter for example (ELI5: there seems to be some gravitational forces acting on large scale things in the universe, so scientists came up with invisible matter that exerts those forces). That is also just a “made up” thing based on observations. There seems to be some gravitational force that’s not coming from something else we can observe, so there’s probably some matter that we can’t otherwise observe.

2. It doesn’t mean it’s useless. There’s some interesting questions it opens up, and there’s some interesting interpretations you can make with this model.

The important thing is the question is usually actually posed as “are we living in a simulation that we could theoretically eventually produce?”. For instance, we seem to only be able to simulate discrete things: the picture on your screen is composed of individible pixels, the numbers have finite precision, time is actually made up of chopped up intervals. But that seems to be the way the universe is also made (as I understand it; quantum theory). Matter is made of indivisible particles, time actually moves in quanta… But we’re not sure that’s actually how it is (important thing about physics, the theories change and refine all the time). Maybe the universe is actually continuous, and we will never be able to harness the continuity for our purposes. Maybe the universe is continuous, and we *will* be able to harness it.

Take that dark matter thing again. A less popular alternative to it is that laws of motion just behave differently at large scales, and that’s why galaxies move in this surprising way. That seems far fetched, but in a simulation, there’s no reason that couldn’t be true. We make games with inconsistent “physical” laws all the time.

My favorite though experiment based on this simulation idea (and this is far fetched, so bear with me, but it does ilustrate what this could be used) is how heaven could work. You know how religious people talk about heaven and hell and what not, and then you ask “ok, well, where is it?”, and the answer is that it’s not here, you can’t interact with it. The reasonable reaction to that is “well, that sounds like the definition of not existing”, how can it be real if we can’t interact with it in any way and it doesn’t occupy any space, how do people move in there…

Now imagine you have a game of sims running. Any time a sim dies, their data is saved to a flash disk or something. Then that sim is moved to another computer, and loaded into another game of sims. There’s no way for the sims in the first game to know about this second game, no way to interact with it. Yet it’s a very real scenario that you can go create right now.

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