Here is an image from that sparked a profound revelation in my understanding:

Now, I always believed if you could construct a big enough machine (say a computer) and you could program it correctly, it could simulate a real universe (like our own) and within this simulated universe, life could evolve, and it could eventually become intelligent and self aware and it might wonder why it exists and what are the fundamental physical principles of the universe in which it lives.

From our point of view, we really have no way of knowing what is actually running our universe. It could be a big machine as described, or it could be a single immortal person with unlimited patience and an ability to move rocks around according to a set of known rules while making negligible mistakes.

In either case, within the simulation itself, intelligent life could exist that is self aware. In the case described in the comic above, a single row of rocks represents a single instant in the simulation. Each instant contains a representation of every single particle in the universe, including all those that make up every lifeform, even the intelligent ones. Each row is a snapshot, with time stopped. And since the "man" performing the simulation is leaving each row alone once it's complete, we have the whole history of this simulated universe laid out on the infinite rock plain, from the very first instant.

I was trying to intuitively understand how the self-aware entities in the simulated universe might perceive the concept of now. If you stop and think about the current instant of time, it is always now. It's like if you're watching a DVD movie and pause the DVD, that instant of now is frozen. What passes for now is an endless sequence of instants, one following another. But each one always feels like now.

In the case of a computer simulation of a universe, I had always expected the simulation would only have stored the current instant of time. Meaning it would take the current state of the universe, do some processing on it, and it would compute the next state of the universe -- after which it could throw out the previous state. This saves on memory. In the web comic's case, however, there is no throwing out of the earlier state. They all exist for all time. So my question was, which simulated universe instant would actually be the one representing now?

Well I decided that each one would represent its own now. Within each instant, the intelligent entities would always be thinking that instant is now. Just as we do in our existence. So I got off that puzzle and was thinking about some other aspect.

I was trying to figure out how the consciousness could manifest itself when after all all we have is patterns of rocks on an infinite expanse of desert. The rocks obviously don't perceive anything. The meaning of the patterns is not at all self evident. The way the rocks are laid out in order to represent the state of every particle in the universe would be inherently arbitrary, dependent on how the "man" performing the simulation decided to set it up. In fact, the reality represented by the rocks only has meaning to the "man" himself.

This seemed hard to grasp. Within the simulation, you can have intelligent entities that are self aware, yet their own representation has no meaning except within the mind of the "man" running their simulation. If he doesn't exist, the rocks on the desert revert to just being rocks. The entities within the simulation don't exist without the "man" to breath life into the universe.

Yet there really is no "life" that the "man" is giving to the intelligent entities in the simulated universe. At best he is aware of a few particles at a time, represented by the positions of a small number of rocks. He, presumably being of human level intelligence, would not be able to perceive the life that exists within his own simulation. It requires too many particles, countless trillions upon trillions of particles for each cell within each and every lifeform within the whole simulated universe. His perception is limited to perhaps a few particles at a time. Trillions together are needed to form even the simplest particle of life. He simply cannot communicate or comprehend in any way the life that exists within his own simulation.

As such, the self aware life within the simulation must exist and have its own reality, and yet it can't be dependent on the "man" for that reality. The rocks are a representation of a real living universe, but only if you read them in a certain way. Nevertheless, the life within the simulation perceives itself to be intelligent and self aware. It doesn't need to understand the underlying reality of the simulation or the underlying physical principles. It perceives itself, and that's all that matters.

Now I was thinking along these lines and I came back to the question of whether our universe is a simulation within some other universe. We really have no way of determining this, unless the simulation's operators care to tell us somehow. The rocks-on-desert universe would obviously have no way of jumping out of their reality to determine experimentally that they exist as patterns of rocks on an endless desert. They could conceivably figure out the physical principles that are operating in their universe, but that's all.

Anyway suppose we are a simulation running in some other universe. That explains our existence, but what explains that other universe's existence? What created that universe? Well, conceivably our parent universe could be operating as a simulation within some still higher universe. Which in turn could be a simulation in some still higher universe...

But when does this end? At some point the chain must end. It must end in a universe that is real and not a simulation. It must end in the first universe. And so the question is, what gave rise to this first universe? Why does it exist? Why does anything exist, and not nothing. We know we exist because we perceive it. But the question is why? A far more likely situation is where there is simply nothing at all. Meaning there is no intelligent life at all, no life, no matter, no universes, nothing at all, there never was, and there never will be.

Yet here we are. We undeniably exist. So still there is that question of why we exist. Religious minded people might fall back on, "Well, God created us." But then where did God come from? What created God? God still has to exist on top of some reality, some other "universe" with its own physical laws and principles. Why does that universe exist, as opposed to nothing? Invoking "God" simply doesn't answer much of anything.

I was trying to grapple with this concept, when the answer suddenly hit me.

The problem with a universe existing as a simulation within another universe leaves you wondering about the origin of the parent universe. Eventually you get to the outermost universe, and you ask where did it come from? There is no still-more-outer universe that could have existed to create that universe, by definition. Because if there were, you would step up a level and ask what created that parent universe. So the outermost universe cannot itself have a creator universe that gave rise to it. The outermost universe cannot actually be running as a simulation anywhere else. It cannot be a simulation at all, because then it wouldn't be the outermost universe. As such the outermost universe cannot be a simulation, as we typically conceive of it, as that would depend on some other pre-existing reality, which is not available, by definition.

So what gave rise to the outermost universe?

The answer is, and this is the big concept to grasp, the universe exists because it can, in theory, exist. Meaning all the physical laws and principles that describe the outermost universe can in theory exist independent of any consciousness that is aware of them, independent of any intelligence, independent of any physical simulation of them. The outermost universe exists, and all that is required is that there exist a set of physical laws, whether or not they have ever been discovered by an intelligent entity, that can describe the universe.

This may be tough to grasp, and I may not be expressing myself effectively. As a side effect, it has to be noted that what goes along with this is that there isn't just one single outer universe. An infinite number of universes must exist, with the infinity of possible arrangements for physical laws, with the infinity of all possible initial conditions. They are all just aspects of information, whether or not they have ever been explored by any intelligent entity. Information itself exists independently of any physical reality. The information itself gives rise to reality.

Take our universe. Imagine there is a compact set of mathematical laws that could be written down on one sheet of paper, and these laws describe all the physics of our universe. The theoretical existence of such a set of laws, in and of itself, has given rise to our own universe. I'm skipping a step where I make the assumption that our own universe is the outermost universe -- we're not actually a simulation within some other universe.

Our universe itself is the manifestation of the physical laws that govern it. There is no "big machine" number crunching those physical laws, performing the simulation. There is no entity that "imagined" those laws. Our universe is a piece of information that is called into being merely by the physical laws that define it. And there is nothing especially unique about that set of laws, except perhaps from our point of view they are sufficient to allow for the evolution of intelligent, self aware lifeforms to exist.

This conclusion, in my opinion, is inescapable. At some point one must come to grips with the fact that there has to be some "universe" that did not itself have a creator. Some universe, such as ours, must have been created out of nothing. And what created it and gave rise to its own reality is the existence of a set of physical laws that it operates under.

There are an infinite number of possible sets of physical laws. And so there are perforce an infinite number of universes. And the universes exist completely independent of each other. They have no way of communicating with each other, because they are each in its own closed off reality. They are not being simulated by anything real, so there is no way to communicate between them. It's like each universe exists only in an imaginary reality.

Yet within the infinite possibilities there must exist realities that involve almost-independent universes that can communicate with each other. Suppose that our universe is shut off from all others, due to our physical laws. That doesn't preclude that somewhere out there exist other universes that are actually parts of an even bigger meta-universe that are able to communicate with their related universes. Really it comes down to anything that can be imagined must already exist in some reality. And more -- even things we cannot imagine must exist in some reality. We're talking about the infinity of all possible realities -- they all must exist. There is no limiting factor, it's not like there is a limit on theoretical concepts. Because there is no machinery that is responsible for running any of the theoretical universes, there is no limitation of any kind within each universe, nor with the total number of universes possible.

As such, there is no guarantee that our universe, or any other universe for that matter, is actually computable. Our universe can operate under principles that simply cannot be simulated by a typical digital computer. Now, I had always rejected such thoughts. I had always wanted to believe that at the bottommost level, the physical laws operating within our universe must themselves be computable -- meaning you could simulate portions of our universe. We just haven't discovered the underlying physical laws, and the ones (such as modern quantum theories and uncertainty and coupled particles and whatnot) currently in vogue are simply wrong or incomplete.

But now I'm not sure. There is no guarantee that the physical laws our universe operates under can be simulated. It is certainly possible to imagine a universe that operates under physical laws that cannot be simulated. And per my underlying thesis, anything that can be imagined (and indeed far more than that) must actually exist and give rise to its own reality. So since non-computable universes must exist, there is absolutely no guarantee that our universe is computable.

Indeed, there is no guarantee of any kind as regards the physical principles governing our universe. There is no requirement that they be simple, elegant, consistent, or intuitive. The only known requirement is that they were sufficiently rich to give rise to us, meaning intelligent life. Beyond that, anything goes. They might be ridiculously, needlessly complicated. Intelligent life could conceivably arise in universes with far simpler, even computable, physical laws.

I'm devoutly non-religious. I don't believe in god, because I've never experienced anything that demands invoking god as an explanation. Yet in truth there is no reason why a god-like intelligence couldn't coexist with us in this universe, operating under its own principles in such a way that we can't physically, using scientific principles, prove its existence. The physical laws operating within this universe might have aspects that we simply don't experience within our typical sphere of existence. We simply don't know.

Anyway, I'm convinced that my understanding above is absolutely correct. Every possible reality exists. Each exists in its own reality, even without anyone having to imagine it. Think about that. There exists a reality where Superman is real. There exist realities where magic actually works. There exist realities where time travel is possible. There exist realities where The Federation is busy fighting Romulans.

Every conceivable reality must exist. And we know this because we ourselves exist and are real. And so all possible realities must also exist, and are as real as we are -- to themselves.

I wonder if our own reality has a back door?

-- Dave Ashley, Hillsborough, North Carolina, USA, Earth, November 23, 2008