Hope folks involved in this type of exploration have it clear in mind that what they are reasoning about it’s strictly the model of the real world only. It’s far from obvious that nature follows anything remotely computational.

> The simulation hypothesis — the idea that our universe might be an artificial construct running on some advanced alien computer — has long captured the public imagination.

Right; that's the feeble public imagination. What captures my imagination is the idea that the existence of the rules alone is enough to obtain the universe; no simulator is required.

We can make an analogy to a constant like pi. No division has to take place of a circumference by a diameter in order to prop up the existence of pi.

The requirement for a simulator just punts the rock down the road: in what universe is that simulator, and what simulates that? It's an infinite regress. If there is no simulator, that goes away.

If certain equations dictate that you exist and have experiences, then you exist and have experiences in the same way that pi exists.

Here is one thing I don't understand about these kind of approaches. Doesn't a computational simulation imply that time is discrete? If so, doesn't this have consequences for our currently best physical theories? I understand that the discreteness of time would be far below what can be measured right now but AFAIK it would still makes a difference for physical theories whether time is discrete or not. Or am I mistaken about that? There are similar concerns about space.

By the way, on a related note, I once stumbled across a paper that argued that if real numbers where physically realizable in some finite space, then that would violate the laws of thermodynamics. It sounded convincing but I also lacked the physical knowledge to evaluate that thesis.

This all assumes there's no computation beyond a Turing machine, right? Therefore, this assumes reality is a simulation on a finite set of rationals?

So, as long as one believes in continuum, this is just toying around?

Simulating a/the universe, and simulating the universe at-or-above realtime are also two separate things.

A non-realtime simulation would allow you certain solutions (such as perfectly recreating a past state of the current universe), but might not allow you to practically see a future state.

These models get things backwards. The universe is a wave function in logic space. It appears discrete and quantized because integers composed of primes are logically stable information entropy minimal nodes. In other words the universe is the way it is because it depends on math. Math does not depend on the universe. Logic is its own "simulation." Math does not illuminate physics, rather physics illuminates math. This can be shown by the construction of a filter that cleanly sorts prime numbers from composites without trial division but by analysis of the entropic harmonics of integers. In other words what we consider integers are not fundamental but rather emergent properties of the minimal subjunctive of superposition of zero (non existence) and infinity (anything that is possible). By ringing an integer like a bell according to the template provided by the zeta function we can find primes and factor from spectral analysis without division. Just as integers emerge from the wave as stable nodes so do quanta in the physical isomorphism. In other words both integers and quanta are emergent from the underlying wave that is information in tension between the polarity of nonexistence and existence. So what appears discrete or simulated is actually an emergent phenomenon of the subjunctive potential of information constrained by the two poles of possibility.

"Example 1. ... After this you physically isolate isolate your laptop, from the rest of the Universe, and start running it..."

However there is no way "you can physically isolate isolate your laptop, from the rest of the Universe" so doesn't that refute this example (at least?)

Like running Kubernetes in a Docker container.

I Don't Know, Timmy, Being God Is a Big Responsibility https://qntm.org/responsibilit

It's starting with the assumption that the simulation would reproduce the universe perfectly; this eliminates a lot of possibilities.

Many would expect that the parent universe would be more sophisticated, potentially with more dimensions, that we can only glimpse through artifacts of the simulation.