The Tiny (and Large) Scale of our Consciousness
Our subjective experience of the world is all we’ll ever have. Yet, it is a mere drop in an infinite ocean when compared to the whole of humanity and the vast universe. I have been thinking about this paradox for the past few days, and like any mathematically-inclined brain, I tried to put some numbers to it.
People like to sometimes say, you are one in a million, which is nice but it’s actually nothing compared to how many people there are! The UN Department of Economic and Social Affairs estimates that the planet will reach a population of 8 billion around the end of 2022. What an accomplishment for humanity! This means that really, you are one in eight billion. This is such an incomprehensible number. Humans have a very poor understanding of quantities that large, so I’ll try to put it into visual terms. Let’s assume you are reading this article on a 1920x1080 resolution computer monitor or phone screen. That means that the odds of you randomly picking a specific pixel is one in 2,073,600. Imagine if you had an array of four thousand similar screens, and you tried to randomly correctly pick a single pixel from the four thousand screens. That is what you represent. You are one single pixel from those four thousand screens! It’s hard to even see one pixel on a single screen, let alone four thousand screens. What a mind-boggling concept. To put it into a percentage figure, you represent 0.000001% of people alive today.
So that’s what your consciousness represents compared to all the humans alive today. But, what about compared to all human experience, ever? From the different estimates I have found online, there have been about 110 billion people to ever exist (give or take 10 billion).
For most of human history, the life expectancy was very short, since a majority of infants died at birth, and we had no access to health technologies. We also did not invent organized societies, agriculture, and specialization of labour until the past few thousand years. This means that the population did not have room to grow very much for most of human history. This phenomenon leads to a fairly interesting statistic: according to this source, about half of all human births (~45 billion) occurred before the year 0 AD, which seems strange to think about, since earth’s population at that time was only about 200 million (40x less than today). I think this imbalance shows just how much the life expectancy has increased in just 1% of the existence of modern humans (2,000 out of ~200,000 years).
Okay, why am I going off on this tangent? One answer is, it’s simply very interesting. But the actual reason is that I need these numbers to estimate the total number of human years ever experienced. From this history of life expectancies, the life expectancy of humans before 0 AD was about 20–30, so we’ll go with an average of 25 years. Estimating the weighted average life expectancy of all humans after year 0 is a bit more difficult since it rapidly increases after 1950, but we’ll go with a rough estimate of 55 years. If we do the math, 45 billion times 25 years plus 65 billion times 55 years gives us a total of four point seven trillion human years ever experienced. That’s every birth, every birthday party, every Joy Division album consumed, every stubbed toe, every teenage heartbreak, every career, every accidental (and intentional) shitting-of-the-pants, every sexual encounter, every marriage, every cancer treatment, every funeral, ever experienced in human history, encapsulated in a single number (plus or minus some error term). Again, what a mind boggling concept! So what do you, the wonderful reader, represent in all of this? If we assume your age to be about thirty years old, then your conscious experience represents 0.0000000006% of all human consciousness ever experienced. Feel special yet?
What about the amount of human consciousness that will ever exist in the universe? It is here that our estimations become very flimsy, because obviously we cannot predict the future (if you can actually do that, please send me an email). It is very hard to say because civilization might end very soon through an event like a nuclear winter, or humanity might survive long enough to colonize exoplanets, in which case a population increase of a few orders of magnitude is suddenly very reasonable. The future of humanity is not a settled question and there are many interesting competing theories for what might happen. For example, the Fermi Paradox is the apparent conflict between the lack of evidence for extraterrestrial life and the supposedly high estimates for their existence (the universe is so massive, it should be teeming with intelligent life). This leads some to conclude that there must be some sort of Great Filter, which posits that there exists some fundamental barrier to life expanding beyond a certain point. According to this theory, the probability that humanity will be wiped out by natural or human-caused events approaches 1 on a long enough time scale.
What’s worrying to me is that it seems like humanity is getting better, not worse, at wiping itself out. There existed no technology 1000 years ago capable of destroying civilization. We should be getting more durable as a species, given our better ability to utilize resources and our redundancy by spreading out the population around the globe, but it seems like our ability to kill ourselves is always outpacing our progress. Such is the double-edged nature of technology. Given a long-enough time scale, even small probability events are inevitable.
With this in mind, I estimate that in the best case scenario, in which humanity manages to beat the odds and colonize the cosmos, there will be about 10–100 trillion humans ever born. The reasoning behind this upper bound is that I find it hard to envision a realistic scenario in which biological humans (as we know them) survive in large numbers beyond the next 10,000 years. I think that future humans will inevitably start to replace their biological systems with computer chips and robotic parts. The human biological machine, while magnificent and magical, is simply not designed to be effective at the tasks that the future demands. Exploring the universe is best left to the robots, who have no need for the cumbersome life support systems and eight hour sleeps that humans require. As robots become more competent than humans at pretty much every task, humans will basically become redundant and biological intelligence will be replaced by machine intelligence. So, by my estimation, you represent perhaps 1 in 100 trillion humans that will ever exist.
After covering the future of humanity, we now take the leap to abstract away biology and humans from the idea of intelligence. If we believe in the laws of physics, in which everything is composed of “stuff” rearranged in different configurations, then there is no “special sauce” that breathes consciousness into human brains. Consciousness has a lot more to do with what is being computed by our neurons, rather than exactly how it is being computed by our neurons. So with this understanding of consciousness as information processing, we can begin to quantify our brain’s processing power relative to the universe. Since all matter is just rearranged quarks, let’s imagine a substance called computronium whose sole job is to compute things as efficiently as possible. Just like there are fundamental limits to other things in the universe, such as the speed of light, there is a limit to how much information can be computed by a quantity of matter. There are a few choices for this limit derived in different ways, but let’s go with Bremermann’s limit which is about 1.36 * 10⁵⁰ bits per second per kilogram. The human brain processes about 8.5 million bits per second per kilogram (1.3kg of matter processing about 11 million bits per second; although surprisingly, we can only consciously process about 50 bits per second).
Okay, now it’s time for the absurd numbers. There is about 10⁵³ kg of matter in our visible universe. So, if we somehow converted all the matter in the universe into a giant computer doing as many calculations as possible, we could achieve about 10¹⁰³ bits per second of information. Since our brains compute at a rate of about 10⁶ bits per second, our brains represent about 1 part in 10⁹⁷ of what information could possibly be computed in the universe.
This number is somewhat meaningless since we will probably never be able to achieve that amount of computational speed, but this whole exercise is just to give you a sense of just how tiny your experience of the world is compared to humanity or the universe. You are one person amongst many people. There were many people before you, and there will be people after you are gone. Your entire existence is one brief flash of light in between two periods of eternal non-existence! And think about all that must have taken place in the universe for you to arrive where you are right now — you are descended from an unbroken chain of organisms all the way back to the very first single-celled organisms to exist on the planet. I often marvel at just how incomprehensibly small we are compared to human history, the planet, and the universe. Somehow, in all of this chaos, the universe decided that you should be you, not any one of the other eight billion people alive today, or 100 billion people that have passed away. It would be such a tremendous waste if we were not to appreciate this fact, and I hope that my writing has given you some perspective on the whole matter.
