Yes, we WILL construct simulated universes of
very high detail someday - good enough to spawn
e-life - and the inhabitants may never be able
to prove they are 'fake'. Of course these sims
may not be done using 'computers' per-se, but
be implemented in fabricated spacetime pockets,
making them not *really* what you'd call 'fake'.
Being human, we'll do it because we can, not
for any wonderful 'higher' purpose.
And sims within sims within sims - no problem.
Now a 'ring' of sims, where the last is the first,
would be pretty cool ..... :-)
As for THIS universe ... yea, it COULD theoretically
be a good sim running on a Pentium-99000 on some
alien grad-students PC while he's off partying at
spring break. It would be VERY hard to prove otherwise
if his software is good. The nearest hint lies in the
quantum nature of things ... that there are 'resolution
limits' to events/time/space/energy ... 'aliasing'.
HOWEVER ... it is quite possible that 'reality' is
a 'simulation' without the need of a programmer, any
formal software or a Pentium-99000.
In his overpriced tome "A New Kind of Science", boy
genius Stephen Wolfram posited (and elaborated upon
in brain-wilting detail) that the stuff of the
universe behaves just like cute little computer
programs called "cellular automata" (the old 'Game
Of Life' being the first popular vision of this
principle in action).
With cellular automata, large quantities of calculating
'cells' are created which don't really DO much beyond
interact in a few simple ways with neighboring 'cells'
according to a few simple rules. The interesting bits
aren't the 'cells', but the EMERGENT BEHAVIORS that
appear on the larger scale as a result of all the
'cells' doing their simple jobs.
Wolfram showed how many of the laws of physics and
matter/energy/time could emerge from lots of 'cells'
doing their little rule-based thing with each other.
Simple emergent properties combine to create far
more complex properties and so forth - until you
have protons and neutrons and all the stuff you
can make out of those.
One interpretation is that he kinda re-invented
'string theory' ... which posits that reality is
an emergent property of zillions of little
11-dimensional string-like energy squiggles. What
you get depends on which strings in what vibration
modes getting together in whatever way.
Nobody needs to create or program these kinds of
'simulations'. They are 'nature', how the raw
stuff of nature bahaves at its most basic level
and what that ultimately causes at larger scales.
And you don't need a Pentium-99000 either. Instead
every 11-D hypercubic Planck unit of the real universe
is a small, rather dumb, little 'computer' that inter-
acts with all the others according to a small number
of rules. Each 'string' is a 'cell' more or less and
does its own little 'calculations'.
It's parallel-processing literally on the universal
scale ... the universe IS "computers" and "reality"
is the emergent behavior. Tweak the rules and you
get a totally different sort of "reality" which may
or may not allow for our kind of physics.
This means our 'reality' IS a "simulation" and
we may, eventually, be able to get a glimpse of
the individual 'cells' that make it work and
how the chains of interactions combine to
generate the larger emergent bits like particles
and fields and energy, space and time. Let's
hope nobody tries to 'hack' this machine :-)
(but someone will, of course)
Theists and philosophers hoping that a 'sim-like'
reality necessarily implies a 'god' or intelligent
'programmer' will find no traction here however.
Blind nature can indeed produce complex emergent
features without any direction/intent whatsoever.
That THIS chain of emergences produced wonderful
US is evidence of nothing ... we could be the
10^999999999-th variation on this cozmic harmony
and fade away as some new patterns emerge - which
may or may not support 'protons' or 'time' or
things in any way like ourselves.