science

Just look at how many people are religious. So yea, people will believe anything for the oddest reasons.

We understand the universe as complex. Honestly though, I wonder if a True understanding of how the universe works—from the fundamentals of which all things may emerge—is rather simple.

For example: within U0, you would control the spacetime simulation of U1. Therefore, what could be a single moment of simulation by U0s standards, could be experienced as trillions of years from within the perspective of U1. They control the frame rate.

They could simulate the fundamentals, fast forward to the end of the universe, and here we are somewhere in the very early part of that having no idea someone hit fast forward because everything is relative for us.

Very simple fix for that perceived contradiction: A simulation doesn't need to simulate everything. All it needs to simulate is the inputs and outputs perceived by a single human being, the observer, me.

For me it would be indistinguishable if the universe I am living in is real, if it's a simulation or if it doesn't exist at all and instead only the things I can perceive are simulated.

Simulating the perception of a single human being should be in the reach of our current calculation power.

Kind of how in a computer game only areas around a player are simulated.

So first is to accept this is more philosophy/religious sort of discussion rather than science, because it's not falsifiable.

One thing is that we don't need to presume infinite recursion, just accept that there can be some recursion. Just like how a SNES game could run on a SNES emulator running inside qemu running on a computer of a different architecture. Each step limits the next and maybe you couldn't have anything credible at the end of some chain, but the chain can nonetheless exist.

If U0 existed, U1 has no way of knowing the nature of U0. U1 has no way of knowing 'absolute complexity', knowing how long of a time is actually 'long', or how long time passes in U0 compared to U1. We see it already in our simulations, a hypothetical self-aware game engine would have some interesting concepts about reality, and hope they aren't in a Bethesda game. Presuming they could have an accurate measurement of their world, they could conclude the observed triangles were the smallest particles. They would be unable to even know that everything they couldn't perceive is not actually there, since when they go to observe it is made on demand. They'd have a set of physics based on the game engine, which superficially looks like ours, but we know they are simplifications with side effects. If you clip a chair just right in a corner of the room, it can jump out through the seemingly solid walls. For us that would be mostly ridiculous (quantum stuff gets weird...), but for them they'd just accept it as a weird quirk of physics (like we accept quantum stuff and time getting all weird based on relative velocity).

We don't know that all this history took place, or even our own memories. Almost all games have participants act based on some history and claimed memories, even though you know the scenario has only been playing out in any modeled way for minutes. The environment and all participants had lore and memories pre-loaded.

Similarly, we don't know all this fancy physics is substantial or merely superficial "special effects". Some sci-fi game in-universe might marvel at the impossibly complicated physics of their interstellar travel but we would know it's just hand waving around some pretty special effects.

This is why it's kind of pointless to consider this concept as a 'hard science' and disproving it is just a pointless exercise since you can always undermine such an argument by saying the results were just as the simulation made them to be.