Human Intelligence and the Multiverse Tuesday, Apr 24 2007
anthropics 6:45 pm
Humans find it hard to imagine intelligences smarter than we are because we’re designed by evolution to ignore the problems we can’t solve and focus on those we can. Doing it any other way would be an inappropriate use of cognitive resources.
What are the top five elements in your body and their relative proportions? You can’t answer? What’s taking you so long? You don’t even know what you’re made of?
Fact is, humans are pretty damn stupid. Not stupid relative to me or stupid relative to Einstein, but stupid in the scheme of things. Stupid relative to what we could be. We can offer any number of excuses, but in the end they’re nothing but excuses.
Homo sapiens evolved out of the primordial muck. We’re what happens when the muck gets just barely smart enough to reflect upon itself and manipulate its environment significantly.
There are two anthropic pressures at play here. Let’s assume, like Max Tegmark and other physicists, that we live in a gigantic multiverse where all possibilities are realized. The sector of the multiverse capable of harboring intelligent life, or life of any type, is extremely small. If our spatial dimensionality were different, or the intensity of the strong force, or the fine structure constant, or any number of other fundamental constants varied by even a tiny bit, life in this universe would be impossible. Tipler and Barrow beat this point into the ground in The Anthropic Cosmological Principle, but we’ve seen it already from numerous physicists.
The first anthropic pressure is the probabilistic bias towards chaos, disorder, and inhospitability to life, intelligent life in particular. In most of the multiverse life is impossible. But in some tiny portion, in which we (surprise!) happen to find ourselves, intelligent life just barely was able to evolve out of the muck and acquire enough cognitive complexity to consciously kill each other and compete for mates instead of just doing so mindlessly.
The second anthropic pressure is slightly more speculative. It’s the idea that intelligent species that are too smart wipe themselves out too quickly to really get anywhere. They build self-improving AIs that ignore their creators and tile the cosmic neighborhood with value structures that are a mere shadow of what the programmers originally meant, or launch superintelligent uploads who slowly, and then quickly become obsessed with the idea of constantly stimulating their own pleasure centers to the exclusion of all other pursuits. Both outcomes radically reduce the number of conscious individuals in existence after that point, thereby selecting those quadrants of spacetime out of the anthropic lottery. We’re unlikely to be born into those regions because they are relatively uninhabited, just like we’re unlikely to be born in universes where infant stars have so much gravity that their accretion discs get sucked in before forming stable planets.
We are born in regions that are typical. Industrial civilizations filled with billions of non self-modifying intelligent social animals, apparently. We’re relatively unintelligent because 1) we just evolved from the muck and 2) because we haven’t been clever enough to destroy ourselves yet. Two factors, any one of which alone would be enough to hold the argument up.
But, worry not. There is no reason to despair. These anthropic arguments for our relative stupidity only underscore our potential for growth. We can improve our quality of life to new heights we could never even dream of.
There is an issue of concern, however. If the future is so much more prosperous and populous than today, then why don’t we find ourselves there, instead of here? If out of every 1,000,000 random beings, only one finds itself in civilizations with only a few billion people, then is it just an enormous coincidence that we happen to find ourselves here?
Coincidence is not a satisfactory explanation. There are reasons to believe that this probabilistic issue is a huge problem. It’s called the Doomsday Argument. You can find numerous rebuttals in the Wikipedia article, but many of them are quite subtle, and if you dismiss the argument merely based on its implications, then I think we can justifiably throw out your opinion.
What is your reason for dismissing the Doomsday Argument? Or if you don’t have one, how do you cope?
There are a few points where the DA has flaws. One; it is unreasonable to presume that the human population will stabilize at all; current UN estimates indicate the population will *peak* at 9.1 Billion, and will fall within twenty years thereafter to 2.8 Billion.
I could also add that the DA preassumes that there is a fixed number of human beings that will ever be born. Under that logic, it is inevitable that there will be an extinction of the human race, barring physical immortality for the final population. In other words; I respond that the DA is obviated by the fact that it is nothing more than an example of the confirmation bias; there is no negative confirmation in the argument.
So: I dismiss it not because it might not be accurate; I dismiss it because it isn’t a contributive argument to the discussion of the fate of the human race.
It would have apparently been logical for every generation of humans to assume they were part of the peak population, going all the way back to our beginings.
Obviously we know this isn’t the case, so all those past generations would have been incorrect in accepting the DA argument. If DA has always been wrong, why should we now fear that its right?
Sounds vaguely similar to The Misanthropic Principle, a kind of mashup of “Murphy’s Law” and the anthropic principle:
“All of history prior to your existence is necessarily favorable to your existence. But once you’re here, all bets are off!”
I’m curious about something, though:
“Coincidence is not good enough.”
…good enough for what?
I think the doomsday argument may be correct. However, if Tegmark is correct, then many-world is correct, which means that we are individually subjectively immortal.
See for example:
http://www.physicsforums.com/archive/index.php/t-59491.html
Even if we have a 1e-50 chance of surviving, it still means there is a continuation of our consciousness within the local quantum many-world. Even a future of being swallowed by a black hole has a quantum branch where you tunnel away.
Note, however, that a high % of the human race might end up dead in the branches where you manage to stay alive despite a doomsday, so it might be lonely and unpleasant for awhile. Probably best to work on making doomsday less likely so as to reduce those future branches….
Which is what we’re doing anyway!
…good enough for what?
A good enough explanation.
Re: the DA:
Instead of talking about human beings, I’ll talk about identical coins. Let’s imagine a 1-dimensional room containing a bunch of identical coins. We can think of locations within the room in chronological terms: “early” and “late”. We have two hypotheses about the room. Hypothesis A is that the coins go on forever; there are infinitely many of them. Hypothesis B(N) is that the coins end somewhere, in a “coin doomsday,” and there are only N coins in all.
Now let’s say I hand you a coin. You know it came from the room, but I haven’t told you which coin it is yet. It could be the first coin, or the billionth, or any other coin. But you’re a Bayesian, so you can quantify your uncertainty: you can report your probability distribution for which coin you are holding.
First suppose hypothesis A. Since there are infinitely-many coins under this hypothesis, you can’t use a uniform distribution. So as the coin index increases, the probability must eventually go to zero. Of course, your distribution could look like anything, but I would use something like an inverse square (maybe a lot of people would use an exponential; I can talk more about my reasoning here sometime). You may or may not agree with me about the inverse square, so let’s call your distribution the “diminishing distribution” in order to be non-specific. Then there is some integer K such that you feel pretty sure (let’s say 90% sure) that the coin I gave you has an index of less than K.
Now suppose hypothesis B(N). What probability distribution would you give for the index of the coin? Well, there are only finitely many, so you could use a uniform distribution. But do you really want to? You already used this nice diminishing distribution. Wouldn’t it be more elegant to re-use that, instead of coming up with some new distribution?
Perhaps you imagined some coin-selecting process from which you derived the diminishing distribution. You can imagine the same process being applied to the finite population. For instance, maybe I had to walk into the room to retrieve the coin for you. I’m more likely to pick a coin with lower index, because those are closer to the door.
At this point, I’ll let you forget about hypothesis A if you like. Who believes in infinitely many coins, anyway? I only mentioned hypothesis A so that you would think of using a diminishing distribution. Instead of considering an infinite room, we can consider finite rooms of different sizes.
One thing you may observe at this point is that for a sufficiently large N, your probability distributions over coins given B(N) and B(2N) are nearly identical. If you were using uniform distributions, they would be quite different; your probability for coin 1 would be twice as big given B(N) as given B(2N).
So if you use the diminishing distribution, and I tell you that you are holding coin 1 (or any coin with index N or less), it has a negligible effect on your belief in B(N) vs. B(2N) (for sufficiently large N).
In other words, there is some N such that, once you know that there are at least that many coins, the index K of the coin you receive has a negligible effect on your belief about N (other than that it must be at least K).
** ”What is your reason for dismissing the Doomsday Argument? Or if you don’t have one, how do you cope?” **
Personally I don’t worry too much about the doomsday argument; I *cope* with it by reflecting that there is simply no point in trying to work out the overall chance that the end of the world will happen, that you will die and that everything you value will be gone for ever. What is the point of working out the marginal probability that you will fail? None, in my opinion! Why? Because the answer you get will not affect your actions.
What you want to do is work out conditional probabilities of success given some action, and then take the action that maximizes the probability of success, where success in this case means a friendly singularity. Doing anything else (like trying to work out the probability of the extinction of the human race, etc) is just pointless and fatalistic.
I have a problem with anthropic reasoning in general. It seems sound, but seems like it should give some absurd predictions. For instance, intelligences that spontaneously emerge (through tunnelling, Hawking radiation, whatever) in the infinity of time following the heat death of the universe should outnumber those born naturally in the early days of the universe – because a given region of space will generate an infinite number of the former and a finite number of the latter over the entire history of the universe – yet we observe ourselves to be in the latter class. The Tegmark level IV multiverse theory looks even more problematic, because I see no convincing reason to believe that intelligences can only arise in a universe like ours – you can build a Turing machine and a replicator in Conway’s Life, even. You probably have to get more complex than that to make intelligence likely to arise, but you still shouldn’t need laws of physics as complex as ours. And if universes have measures according to the Kolmogorov complexity of their laws (doesn’t Tegmark suggest this?), we would overwhelmingly expect to be in a simpler universe.
I also, personally, take umbrage at the concept that self-repeating patterns cannot emerge in any other set of physical laws other than our own. Ours is uniquely tailored to the universe we exist within, and as such it is unreasonable to expect that any sentience resembling our own would arise in any universe not fundamentally similar to our own.
But does that even *IMPLY* that sentience is impossible in even the majority of universes? Or just that *WE* are impossible in the majority of universes? Different physical laws would result in different systems. Life is nothing more than an assemblage of self-repeating patterns. It seems to me that there is nothing in that which in and of itself *REQUIRES* a universe even remotely similar to our own. Carbon-based life? Certainly. But to equate “Carbon-based life” with “The only possible form of life”? THAT is anthropocentrism.
Imagine for a second a universe where the proton does not form. Is it impossible to believe that such a chaotic maelstrom of electrical fields, absent any other material, would not given a long enough period start to assemble into self-repeating or sustaining patterns? Isn’t that what a plasmoid is?
… Okay, I’ll stop ranting now. :)
I love your 404 page…It came up when I clicked on the link to Bostrom’s utopia article. :)
In the grand scheme of things, there will allways be many more people born after you than before, so, even if you were born much later than now, it would seem, to you, like you were born near the very beginning. Therefore, your arrival is strickly random, and you would be asking the same question regardless of when you would be born, and the answer would be the same.
The doomsday argument has nothing to stand on, every “point” in the timespan of humanity will seem very similar, one apparent existential threat will replace the one that came before.
While I do not agree with actual estimate the wiki article makes for the maximum actual amount of humans, I do agree with the actual argument.
In a system where time exists (such as our universe), things are finite. That is, everything that has a beginning, has an end. Eventually, anyways.
The solution? Break time. That’s the only possibility, supposing that human population growth is stable (which I do not concur to), to avoid reaching the N-point.
So the only possibility of avoiding the end in a finite system is make the system infinite. How, I have no idea.
Oh, another issue with the Doomsday argument is that the future number of people can have no causal influence on the people alive now – thus the simple fact that we are alive now has the same posterior probability no matter how many people are born in the future. This still allows anthropic reasoning to be used on things like the laws of physics that do have a causal effect on here-now.
I don’t find the Doomsday argument at all intuitively compelling. Beyond the concept of the observer existing at a certain time, it refers to no observations. For present humans, the reasoning of the Doomsday argument is excatly as compelling in both the possible world where humans are about to go extint and the possible world where there will be an immense amount of sentient beings in the future. In both cases, the same number of observers will end up existing in the present. In the situation where there will be no extinction and a massive expansion of sentience, the few improbably individuals who end up existing at a time similar to ours can be exactly as convinced of their impending doom as we are.
I’m genuinely puzzled why people regard the Doomsday argument as anything other than a curiosity of probabilistic reasoning.
I may be misunderstanding this, but it seems to me that if you use the wikipedia article math, but you happened to be a clever chap in the distant past, then n=(the 53 existent beings sufficiently evolved to count as homo sapiens) and N
Please disregard previous post, I tried to use a less-than sign in an equation and it apparently got treated as the beginning of an HTML tag.