Looking for a critique of the following write-up:

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Since the initial conditions for the simulation must be relative to
some observer, the simulation itself would be a simulation of the
observable universe according to one observer.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The above is false.

Looking for a critique of the following write-up:


The Problem:

Create a computer simulation of the universe

This is a software engineering problem that requires some physics
knowledge.

It is tempting to think that something like a pong game, a three
dimensional space with some objects boucing around and a few more
interesting features like mass and thermodynamics, would be adequate
enough to solve the problem of simulating the universe.

But it isn't that simple, according to the scientific knowledge we have
of the universe today. Specifically, that kind of model fails to
account for the insights provided by relativity and quantum mechanics.

Newton's model was based on absolute space and absolute time, but
Einstein abandonded those concepts and made a model from relative space
and relative time that combine to make a four dimensional structure
called spacetime. In doing so, he was able to eliminate an absolute
reference frame, which allowed him to make the speed of light constant
in all relative frames, providing an explanation of the
Michelson-Morley experiment among other things.

If our solution to the problem is a good solution, the simulation
should reproduce accurate predictions of the results of actual
experiments, such as the Michelson-Morely experiment. Which brings up
The Relativity Problem:

Create a computer simulation of the universe using spacetime

The wikipedia states:

"The basic elements of spacetime are events, these being represented by
points in the spacetime. Examples of events include the explosion of a
star, or the single beat of a drum.

A spacetime is independent of any observer. However, in describing
physical phenomena (which occur at certain moments of time in a given
region of space), each observer chooses a convenient coordinate system.
Events are specified by four real numbers in any coordinate system."

Spacetime may be independent of an observer, but in order for it to
actually describe the universe, we must supply it measurements that are
depedent on an observer. This is important to know.

If a computer algorithm were made for spacetime, that would not be a
computer simulation. To create a computer simulation we would need
initial conditions to which our algorithm can be applied successively.
Since the initial conditions for the simulation must be relative to
some observer, the simulation itself would be a simulation of the
observable universe according to one observer. While that simulation
may provide enough data to use as initial conditions to simulate the
universe according to a second observer, there are several issues with
going that route:

1. there will be observers outside of the original observer's light
cone, meaning the scope of the simulation will always be severely
limited
2. even if another set of initial conditions can be derived from the
original simulation, that requires the initialization of another
simulation

Those are severe problems that boil down to one critical problem: in
order to simulate the universe for all observers using spacetime, more
than one simulation is required.