On Facebook, in response to this article that's been circulating today for some inscrutable reason, one A. Melaragni said:

Apparently the guy is just talking about our own galaxy; there are BILLIONS AND BILLIONS of galaxies in the universe. Not to mention that even if other life doesn't exist in our galaxy now, that doesn't mean it never did or never will. There is just so much room out there that I think it would be bizarre if life DIDN'T exist elsewhere.

Which got me thinking. In the absence of proof positive one way or another about the existence of life elsewhere or elsewhen, we can still do some perfectly legitimate Bayesian reasoning based on what we've [not] observed, and how the universe seems to work.

While I don't really buy it, I'll concede there are some legitimate reasons to think we might be the only life anywhere. The only other plausible option is that there is an abundance of life: is, was, and will be.

My reasoning is that physics doesn't do one-offs. You don't see a new kind of particle exactly once and never again, you don't see one wildly unique type of stellar body sitting among trillions of others in our galaxy. In general, there are strong mathematical reasons why if anything happens once, it (or something similar enough) will most likely happen twice. And if there's anything less likely than someone happening just once, it's something happening just twice, which would make a mockery of probability.

So, I figure it's probably not just us out here, and if that's the case, it's *certainly* not going to be just us and one or two other planets of life. Let's consider the two main possibilities.

In the scenario where intelligent life happens, and where you accept my assertion that there will probably be a lot of it, we can draw some conclusions. Crucially, **we are unlikely to be unusual**, within the range of all life that eventually takes form. Barring a meddling God, the various salient characteristics of a lifeform—longevity, intelligence, size, high reliance on optical/EM sensory input, overall temperament—are gonna end up distributed as big fat Gaussians, and we're gonna be right near the big fat middle of them for most of these things. Yes, there will be truly alien and bizarre creatures out on the fringes, so that's fun, but it's not us.

This also applies to our timeline of development of technology relative to others. We are one species selected at random from all those who have or will exist. There are some cosmological reasons why we might be one of the earlier ones, but I feel that's heavily outweighed by the implicit probabilistic evidence under discussion; if there are to be a million different life-bearing planets, what are the odds we're the very first to start to get our shit together?

Then of course you run into your Fermi paradox, which on the whole is pretty ominous. Without getting too sidetracked in that, it strongly suggests that either we'll never make it to the stars, or when we do, it will be in a form or mode unrecognizable by present-day us.

To recap:

- If there's any life besides us, there's probably a shitload of it.
- If there's a shitload of it, lots of them probably have a huge head start.
- For whatever reason, they're all gone, unrecognizable, or (at best) undetectable.
*Without exception*. This implies that whatever the attractor at work might ultimately be, it is likely inevitable and undeniable.

Basically, for anyone who dreams of 50s-scifi-style cruising around the galaxy and meeting aliens, give it up. Either there aren't any out there, or there is some overwhelmingly strong reason not to make contact on those sorts of terms, or there'll be some pesky obstacle like inexorable self-annihilation in the way. If we ever do make it to the tipping point where we have the social and engineering infrastructure for interstellar flight, and start doing it up in earnest, I figure that's the nail in the coffin for there being any other life out there. So, the other scenario:

In this scenario we are, somehow, a black swan—most likely, there would still be an infinite number of aliens in our infinite universe, but they'd be so negligibly rare as to essentially guarantee none in our light cone, which means they effectively don't exist. There's not a whole lot to say on this other than to point out the silver lining—that the massive, invisible, all-subsuming agent watching us hungrily from behind the curtain of the Fermi paradox would suddenly become a non-issue.

It may be a lonely existence, but this scenario is one in which there's no especially good reason why we can't go exploring all over observable space and spread like cancer. There just won't be all that much more to do out there, at least until we say "okay, fuck it" and seed some new form of life deliberately. I think that, of the two scenarios, this is actually the better deal, as it sidesteps the many and sundry sinister explanations for the current deafening silence.

**Note to self**: there was something worth exploring there that I skipped by. Given certain kinds of systems governed by a relatively small set of rules but seeded with some level of random initial conditions or ongoing perturbations, is it in fact true that it can be less likely for something to happen twice than to happen once? And if so, how much must a thing have to happen before the probabilities pull even again? I think there could be depth there. Maybe more weight behind %0%, %1%, and %oo% being the only relevant quantities of things. Which is arguably already well established. And %oo% is just a gussied-up %0%.

But I'll go digress.

]]>*As usual, the main ideas here are wildly speculative, written down as food for thought. I am not claiming to be a cosmetologist or astrologer.*

For the purposes of this post, let's suppose that the universe is ultimately discrete. By this, I mean that when you get down to its most fundamental level, there are "pixels" in one way or another, some ultimate underlying property of everything which is atomic and indivisible, digital and not analog. If the uncertainty inherent in quantum mechanics drives the deepest level, then the rest of this may not apply, but it is certainly possible that there are deeper underlying forces yet to be identified, so we don't know yet.

Note that the discreteness of the universe does not preclude space or time from being infinite (although it is arguably an infinity of a lower order). However, I'm about to suggest here that it *does* link the finite-ness of space and time inextricably: either they are both infinite, or both finite.

Consider a discrete universe with a finite volume, but lasting forever. Any such universe could be reasonably treated as an enormous finite-state machine. No matter how vast it might be, there would be only so many possible configurations it could take on before repeating itself.

If its physics are deterministic—configured such that any given arrangement of "pixels" (or "atoms" or "bits") necessarily defines its successor—it would use only a tiny fraction of all possible states. Even if there is some purely random influence at that level, and it could conceivably reach every single possible state, there would still be a limit to the number of possible states.

Granted, it would be enormous; for example, assuming a universe comprising %10^100% bits, there would be %2^(10^100)% possible configurations for it to be in at any given moment. Note that this is a big fucking number; we're talking %~30000...0% possible states, where the %...% is replaced by about %1,000,000,000,%%000,000,000,%%000,000,000,%%000,000,000,%%000,000,000,%%000,000,000,% %000,000,000,% %000,000,000,% %000,000,000,%%000,000,000,%%000,000,000% *digits*.

If we consider its progression over time, we're looking at all the permutations of those configurations, representing an upper bound on every possible narrative the universe could follow, of which there would be %2^(10^100) !% configurations. The number above, which we could not write because it has more digits than the number of electrons in the observable universe, is the number of *digits* of this new, incomprehensibly larger number. (Yet still finite, so overall, pretty small as numbers go.)

But I digress. So let's focus on the deterministic case, which seems likely to be the correct one in a discrete universe. If we have a finite number of bits, that means that sooner or later, we're bound to come back to an exact state that already occurred in the past. That point necessarily defines a set of states through which the universe will cycle, over and over, forever.

Each cycle will only take a finite amount of time. This means that time cannot truly be termed infinite, since there would be absolutely no reference point by which a state occurring in one cycle could be distinguished from the same state in the next cycle. Time would be a loop of finite length. Thus: *in a deterministic universe, finite space implies finite time*.

What was less clear to me is whether the converse follows, that finite time implies finite space. The symmetry of space and time biases me strongly towards thinking this is probably the case, but let's look at it.

In the finite-space situation above, I claim that time is effectively finite because there are a limited number of distinct states, rendering it meaningless to speak of any time beyond that necessary to differentiate each of them. In a finite-time universe containing infinite space, we might be tempted to look for the same general pattern; a finite cycle such that regardless of distance traveled (rather than time elapsed), there are a limited number of possibilities one can end up with.

Cue relativity.

Let's consider our infinite-space universe as an infinite number of bits spiraling out from a point-source observer (you). Pretend there is no speed of light limiting things in this universe. Even with a finite lifespan, the universe would still very much be spatially infinite, both in the sense of being able to observe every single bit in that infinite string, and secondarily the possibility of traveling an arbitrary distance within it so that you are now surrounded by an arbitrarily large amount of completely different information than wherever you started. This is clearly not analogous to the finite-space situation above.

How might we fix that asymmetry between time and space if we were designing a universe and wanted to keep things simple and balanced? Mix in relativity. With the speed of light governing things, any observer is now limited to a light cone demarcating a strict upper bound on the observable universe; this is equivalent to establishing a finite limit to the number of bits and consequently number of possible states perceivable for a finite interval of time.

In that sense, the invariant nature of the speed of light seems almost specifically tailored for the *purpose* of linking space and time together. All of the fun relativistic side effects you end up with are logical necessities conspiring to limit the information available starting at any point in space over a given period of time. Thus: *in a deterministic universe, finite time implies finite space—so long as you have relativity!*

Finally, the logical corollary to these assertions, taken together, is that infinite space implies infinite time and vice versa.

**Conclusion:** Maybe that's why relativity.

There's this longstanding observation that we live in a "fine-tuned universe," which is to say that several fundamental physical constants (e.g. strength of gravity, electromagnetism) appear to be set *perfectly* for us. If they were any different, even by one part in a billion, the universe would

There's this longstanding observation that we live in a "fine-tuned universe," which is to say that several fundamental physical constants (e.g. strength of gravity, electromagnetism) appear to be set *perfectly* for us. If they were any different, even by one part in a billion, the universe would have evolved very differently and failed to give rise to sufficient complexity to eventually enable life as we know it. Which, at first glance, seems awfully suspicious.

One proposed explanation for this is the **Anthropic Principle**, which tries to couch the whole thing as a selection effect. The claim is that obviously the cosmological constants had to be set that way, because if they weren't, nobody would be around to notice, and therefore no meaningful conclusions can be drawn. While the basic premise makes sense, arguing that there's nothing to be inferred strikes me as a load of horseshit.

If there were only one universe (ours), with one set of laws and constants, the probability of it just happening to work out like this is so close to 0 as to be negligible, barring the possibility that it was deliberately engineered that way (which is a whole different discussion.) So, it seems extremely likely to me that this should be taken as strong evidence in support of a multiverse of one form or another, consisting of a vast number (or more likely, an infinite number) of universes with varying laws of physics and initial conditions. This would neatly account for our seemingly extraordinarily unlikely circumstances, and incidentally explains and recolors Occam's Razor not just as a heuristic, but a de facto selection pressure in its own right.

So what?

Well, now let's look at consciousness and experience as computation. If you discount the notion of a soul, or other hand-wavy quantum mechanical effects, all we are is our own brain, fed appropriate input. The brain is presumably Turing-complete, essentially a computer— or more to the point, operates on principles that could be precisely modeled on a computer. You could be running on a PC right now, and if the model and coding were all correct, there'd be no subjective difference for you.

Of course, that's just The Matrix 101. But the problem is, things get weirder. It turns out that a huge variety of systems can be made to be Turing-complete, which is to say capable of carrying out any computation that a PC (or a brain) could execute. Bored CS students have designed Turing machines out of tinkertoys and Minecraft levels— hell, you could even have a hundred Tibetan monks pushing around beads on abacuses, and so long as they're conducting computation that can be isomorphically mapped bijectively to neural wetware, the end result is that you, your whole life and apparent consciousness and free will could be no more than a consequence of those beads getting pushed. Although this sounds a little out there, it all logically follows, and I think a growing consensus is emerging about it among people working in these fields.

So what's the first thing got to do with the second?

If we assume all possible universes exist and the level of algorithmic complexity of each universe is uniformly distributed over that infinite set (which seems like a plausible assumption), then universes dominated by the simplest of laws will be infinitely dense relative to more rarefied and complexity-heavy universes like our own. I expect that many of those universes will be appropriately configured such that they end up running a huge amount of computation, whether through a physical substrate (think an infinitely physically large universe consisting of random quantum fluctuations affecting clumps of molecules that tend to form NAND gates) or directly in some kind of even more abstract mathematical formalism.

If that's true, then every person that does exist or could exist and every life they could live would be inevitably simulated by just a single one of these Turing-verses. Which would mean, in turn, that it is essentially mathematically certain that you're not really here in the sense that you think, but are instead one of those simulations in a completely different and alien universe.

Now the question is how one could falsify this whole hypothesis, or better yet, if it turns out to be true, how one could arrange things in our universe such that we tunnel our way out into some control of the underlying Turing-verse.

And it's also conceivable that carrying out computation itself is not necessary to give rise to our subjective reality. It may be that just the pattern itself, in static form, is sufficient. That would be a beautiful thing, because it would open up the possibility that the only thing that exists in all of creation, across all universes and all time, is a single number encoding all things, in exactly the same way that any phone number, or book, or data representations of entire lives and worlds are contained within the digits of the number pi.

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