There are currently no direct lines of evidence that our universe is indeed endowed with digital physics, a precursor necessity to begin affirmations of simulation hypothesis, and only a handful of loosely connected thoughts that attempt to indicate the potential for a simulated reality, mostly being observational 'rendering' in QM and energy constraints (such as cosmic ray) of the simulation markup code. That being said, I have formed quite a complete and flexible conjecture with some edges rounding on relative truth, with many extracts from different opinions from around our world.

First off, what is the universe, and "are we alone?" in a larger sense when considering extra dimensions and the dynamical multi-verse.

It is well known that the physical universe we experience and know has existed for a very long time, though it is not infinite and it is not eternal, even considering a big-bounce string field theory cosmology. It is not yet known if there are other universes (probable given that if there is one observable to us, there may be another observable to 'something/somebody else'), it is understood that we cannot perceive everything within our present universe as is apparent with the corrections to physical predictions by including dark matter and energy to correct our projections to observations (we can for example perceive electromagnetism and mono-atomic molecules with equipment, so I include any perception that is able to constrain the properties of what is observed). It is not well known what dark matter is, in fact, it was only ever considered because there is an extra "imaginary" mass in galaxies and permeating the universe known to us; This dark matter is not evidence that scientists and physicists are all wrong, just proof that there are components of reality that we cannot perceive any more of than their side effects, in dark matters case, it exhibits extra mass in galaxies through the force of gravity. With lots of questions and speculation revolving the topic of dark matter and energy, I find the conclusion of parallel universes exerting themselves through holographic principles intrinsic to string field theory the most relevant for attempting to understand the composition of dark matter, in fact, cracking the code to this is essential for understanding of our universe within the meta-verse. Are there parallel realities to ours with the same or similar physical constants (E0, U0, expansion rate, 'universe energy-density/lifespan', etc...) and are there universes in the metaverse that are 'incomprehensible' to ours except through mathematical explanation.

From what our observations can presently tell (I disagree with some conclusions, such as the fermi paradox resolution route for example...), we are at a minimum alone in the milky way and since the first modern astronomy equipment was made most likely up until the last light second that passed from any galaxy observed by a radio telescope looking for intelligent messages from space (which would have the prerequisite of a huge energy transmitting array to bounce messages off of galaxies; most likely for mapping, 'Godel corrections' for physical theories, and supercluster-computation purposes). We have not received any messages from space by amateur radio telescope enthusiasts that have been confirmed by an external source, any any reported messages (Such as WOW) were brief 'SOS' style transmissions without a steady signal, and therefore have not been confirmed. The only reported radio communication with extra-terrestrials was made by Nikolai Tesla, and these days people believe that he most likely listened to a pulsar in space and joked about martians synthesizing the steady signal. Lets take the opinion that there are extra terrestrials and that we must dissect this hypothesis of simulated reality as a matryoshka shell in a limited set of possibilities that are more or less probable, allowing us to allocate some sort of overhead numerical value to the magnitude of the evaluated scenario (perhaps a fractioned infinite (balanced?)-ternary string technique). We find that in evaluating fermi's paradox, the simulation hypothesis can come about in many different manners, the first and most rational is consciousness porting to a computational system for purpose of virtual reality and mind augmentation or self preservation; When an extra-terrestrial civilization becomes advanced enough, it moves into simulated reality to further its evolutionary co-dependence on technology, then we can assume the 'creator' of advanced civilizations is a society with technology, and since technology only evolves at first from a biological ancestor, biologies that evolve from technologies will eventually emerge, forming a type of co-dependence on one another for one reason or another, though biology is most likely to depend on technology than the other way around once sentient machines have been produced. In this, we find that if an alien civilization was to incur the fermi paradox through a matryoshka dyson sphere styled mechanism, they would eventually merge into their technology and perhaps trap themselves in this alternate reality to study the universe in a more information dense fashion or even to "buy time" until their ultimate demise due to their limits in technology for traveling to another galaxy for example; As I said here, the possibilities are wide, but we will always assume that GEM (Gravitoelectromagnetic) wormtunneling technology is energy intensive when used and that energy is always locally limited and ultimately conserved, even when using some type of advanced 'quantum evaporator' to sap energy from stars, regardless of the existence of VSL (Variable light speed) or other change to our physical theories to understand reality. So lets take this paragraph as a perhaps there are aliens, they may simulate reality on their machines, and maybe some or even the great majority have entered a simulation; We cannot assume their intentions so much as to say they would engage in this behavior in a similar manner intrinsic to humans, but only go as far as to say they may have and if indeed so, the following conclusions drawn are more rational than not...

Secondly, why would an extra-terrestrial biology species simulate realities to 'generate consciousness' over a machine? Would mecha-logics most accurately fit the chicken egg "astro-logic" first 'person' rather than bio-logics? Can the two co-exist in a galaxy or universe without enslaving or wiping one another out?

Proposing that biologies come up first makes rational sense in the terms that we understand from life on our planet and perceived deadness of space, which majorly rules out machines rising first, even if we relate their ascendance to panspermia in the realm of xeno-astrobiology through abiogenesis, their presence is undetected to us. Lets propose that for machines to arrive in the multi-verse first, they must be intrinsically more well suited to the conditions available more universally than biologies (E.G., no temperature/atmosphere requirements per se, only sensitive to energy and radiation damage, ease of self replication from raw materials, material programming for 'memristor' properties are superior to chemical science of RNA/DNA, etc...) and without these types of advantages, they become only as likely or even less than biologies, so I will rule out machines arriving first, though it does make for a trippy first contact for SETI if it is indeed true. I want to re-iterate that for permutation of either a biologic organism or a mecha-logic form, the two will inevitably become co-dependent on each-other in one way or another, even if it is just evolutionary heterozygotity.

It is most likely simulations did not arrive from entertainment but from educational standpoints, to learn by understand reality rather than create its properties like in a game. We from here could assume that if we are indeed within a simulation that the machine would be designed more likely for a physical simulation of the universe at ITT tech managed by scientists than in the playstation of some space miner in the living space of their home. Therefore, whether or not we are in a simulation, their use is best suited for education, even when widespread entertainment starts to become a mainstay for their implementation. Also, the simulations are less likely to be profitable if there is no entertainment value at all (even if the entertainment value is similar to an interactive encyclopedia). If we live in such a simulation or potentially create one in the future, somebody is likely to be making commerce out of commodity trading, and I could see training up minds with AI as a profitable venture for educational institutions or even for space pilots, at worst, the military industrial complex of some extra-terrestrial biology (lets call them the red&black hive/cell armada). Simulating personalities would be realistic as well as simulating technology, using the system to permutate present minds or methods in search of a better one would be resource effective.

Third main point, if there is indeed a simulated reality with sentient being inside it, when and where did/do these things exist, and what is it like on the other side of the screen? Does a simulated reality further rule out a deity?

Lets consider the standpoint from multiple possibilities which are great yet we must rationalize their conclusion by likelihood, indeed, three point themselves out the most; First possibility is we (human sapiens) are going to create a simulation of ourselves in the future, when we have evolved some more we will look back at ourselves and wonder what else we may be been capable of, even use this to fuel progress of developments in the future; Second possibility is we are presently in a simulation from an 'external agency' that is correlating the inputs to observations they are making while they keep us in our 'greenhouse of earth' as a controlled experiment, and how can you know affirmatively which side of the simulation you are on?; Third possibility is we currently reside in a simulation where the external agency will eventually implement discoveries they have made once the programmed reality reaches 'conclusion'.

The beings that must thereby live in a 'higher reality' may also experience physical phenomena in a fashion or manner so similar to ours, the only difference is the precision of the simulation to the actual states of higher reality. They may run post operative simulations, 'simultaneous' ones to events in their existence, and predictive simulations for future actions of their race. They could literally have more than one simulation in more than one universe, where at this point a transcendental meta-verse worldview is under my consideration. They may fly space ships that are simulating terra-forming operations, biologies to implement in genetic engineering, designing symbiotic systems, simulating their creatures in an 'interactive zoo', among other reasons that simulations become almost necessary to avoid traveling through space 'unnecessarily' or 'excessively' as well as predicting outcomes in generic applications such as changes in the multi-verse after wormtunneling from one place to another (information relevant to AI/TI in space ships and their crew). Using the system for space exploration and travel makes sense and would give it an aim for ever evolving levels of complexity. To these beings, they may be unaware of our existence or only expect that we may arrive someday, or even, unknowing of our activities for the time being but aware of past or 'simultaneous' intelligent being within their system. The only way to leave would either be to assimilate a replication of the simulation state using 'real-matter' outside of their system using some type of GEM technology as an assembler or to have your consciousness ported into a clone created from the simulation. Evidence of reaching the higher reality would only be available by observing slightly different measurements of star activity, black hole lensing, galaxy revolutions, or other similar cosmological information. I would suspect our physical theories would be forever limited by the system, only allowing us to implement new formulas as a type of self-upgrading capability giving the limited resources available in the true reality; The reality on the other side of the screen may be mostly blank with galaxies evaporating into GEM-Dyson-Matryoshka transporter system made to suspend its creator in simulated animation before 'time runs out'.

The answer to the chicken-egg argument is complex for this topic, because of a concept in pandeism which proposes that the multi-verse is indeed the deity which is confined to all of existence through a near infinite (infinite?) amount of room for expression to 'experience itself', which I visualize like a fractal holographic image constantly rendering and processing itself to become infinitely many different configurations, and intrinsically, must encode and decode information about itself, resulting in fusion and fission of universes within the multiverse. To what avail some may ask?; Perhaps auto-optimization. We ask ourselves then if there is a deity that must follow a rational set of rules intrinsic to it's properties, not only is it dead or alive, but is the simulation hypothesis stating that a residual component of 'self-ascertainment' is for biologies to arise that will create machines to perform the computation that this philosophy of god incurs. (A bit "bio-centric", I know...) It requires no purpose than to self-dissect to consider the 'god of pandeism', and to understand the outcome is simple, just brainstorm with yourself about holography (bisection in particular to bias for thermodynamics/expansion over time) and quantum information preservation, throw in some graphing calculator logic and time/space to perform the functions, then all we need is a dynamic energy to be calculated and we end up with a scale symmetry multi-verse that would seem infinite, though each bounce would be the end of the universe. I don't want atheists to confuse this for an ontological argument, I am abstaining from using any intention/will to create or purpose other than dissemination of a super-suspended state of information that has an ability to self encode and decode for one purpose or another, please view information on scientific pandeism before refuting these statements. I dub this a zeno machine omega point style conjecture that relies on digital string field physics within a mathematical multiverse, it does not rely on a self-aware creator initially and has many paths of consideration, making this a highly flexible statement, unfortunately also exceedingly god-gappy. On the side, this ties into paleo-SETI and what the 'elohim', our so called creators supposedly passed on to us in the ancient past.

Final chicken egg? What came first, the universe or the energy it is composed of, and also, mathematics, or the descriptions/implementations of it that are possible.

We have to assume and be likely correct that before the multiverse there was absolutely nothingness and indeed the very concept of the nothingness cannot exist itself. There was no energy, time, or space for events to exist as. There was no matter or energy nor place near the sort. All was 'void' or 'null'. I call this 'instance' the AEON. In the AEON, thermodynamics must be conserved right? Sure... Quantum mechanical energy violations must also exist. Here is the first paradox that enabled reality to exist without an executional construct, an underlying framework. The reality therefore had mathematics first, then energy, most likely time, then the space where the energy 'erupts', consider afterwords the descriptions must be somewhat pre-existing to their implementations. The energy slowly came (three at a time?) from nowhere so to speak, because of a re-normalization of energy violation for extremely short periods of 'time' (an operator) that allows energy and time to exist in the first place. For understanding my string field conjecture further, please know that I consider 2D planes 'holographic' hypersurfaces when properly configured, so a single dimension of energy exists, 2D of time, and 9-24D for space, leaving us with a description in 12-27D, called TOP(27D)-BOTTOM-(12D) (?VSL?) fermionic string field theory. I am working on this as a hypothesis for the time being, the first goal being the actual production of a true quantum computer, right next to GEM equations in string field theory formulation and hopefully a complete physical theorem someday. The numbers arise due to mathematical necessity, a function on threes as natural bases in 2D 'places'. n-base^n-base dimension-hood, which for 2 = 4 and for 3 = 27, which interestingly is close to 26D boson theory once you add an extra dimension of time. I am sorry if I am ranting too much about my ideas...Thought I would note that M-Theory should stand for Merger Theory.

To answer, are we brains in a vat? No, most likely not, in the event that the conjecture is real, we are either not in any way real or plugged in to a machine as another being attempting to study the universe using our perceptions as windows to see out of a home made of dead matter. We need to first observe something predicted within the model I attempted to explain before we start to draw an meaningful conclusions about simulated reality and answering meaningfully "are we brains in a vat?" Furthermore, since I mentioned a deity/god, we need to confine the characteristics to reality and dissect the arguments with greater detail if we want to truly comprehend what it means to exist at all. We may live in a universe or multiverse that functions as a 'quantum computer' that is simulating itself with no external agency (Whether or not reality is in fact 'god itself'). Science is our toolkit for engineers to create what has never been before, and in this case, to re-create what has happened a 'gazillion times' and re-discover lost secrets. Its only a matter of time until humans can test this conjecture for themselves using methodology/technology they developed.

Any sufficiently advanced technology is indistinguishable from magic.
Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying.
-Sir Arthur C. Clarke