Here’s a question that has a direct bearing on both the Drake Equation and the Fermi Paradox: When did life first emerge in the universe? More important to the SETI discussion, however, is determining the earliest point at which a radio-capable or Singularity era intelligence could have emerged. My initial suspicion is that the conditions required to support intelligent life have been established for quite some time now – a conclusion that will only reinforce the Fermi quandary rather than diminish it.
A lot of hand waving goes on when people dismiss the Fermi Paradox. The fact that the universe isn’t already teeming with ETI’s and machine intelligences is more disturbing than most people realize. One such person is Ray Kurzweil who believes that we are the first (or among the very first) intelligences in the universe to approach the Singularity. I find this absurdly improbable, but it’s an hypothesis that I’m willing to entertain.
For the sake of this discussion, let’s set aside Ward and Brownlee’s Rare Earth hypothesis and invoke the self-sampling assumption about our conditions here on Earth. We can heretofore assume that the circumstances on Earth are extremely typical in regards to how life emerges and evolves.
According to cosmologist Charles Lineweaver's estimates, planets started forming 9.1 billion years ago. Obviously, radio-communicating or pre-Singularity intelligences didn't emerge overnight. So, how long does that take? Using the Earth as an example we can come up with a rough idea.
Life on Earth first emerged about 600 million years after its formation (that’s awfully quick – a strike against the Rare Earth hypothesis, I would say). Consequently, given similar conditions in other parts of the universe, I’d say that life could not have arisen any earlier than 8.5Gyr ago. What I’d be interested to know is, in what way, if any, were planets and solar systems different 8.5Gyr ago as compared to those which formed 4.57Gyr ago (which is when the Earth formed)? Would any of those differences negate or retard the processes of life?
The next factor to look at is the complexification of life. On Earth, it took RNA/DNA about 3.7Gyr to get to the point where it was able to express complex land dwelling organisms. This is the time when, about 220 million years ago, that dinosaurs emerged. It’s conceivable that hominid-type creatures and their attendant civilizations could have emerged around this time instead of super-predator dinosaurs. Let's work with this assumption.
Now, I suppose we should account for the mass extinction events that characterized the early phases of Earth. Given the short period of time in which it’s taken Homo sapiens to emerge from beast to virtual cyborg (less than 2 million years), it’s safe to say that the high frequency of mass extinctions wouldn’t have been a factor.
That said, NEO impacts and other mass extinction events have been the cause of drastic evolutionary re-starts, but have decreased in frequency over the course of our solar system’s history. The solar system is stabilizing. A fair question to ask is, were mass extinction events necessary for the emergence of intelligence life, and if so, why?
Given the length of time required to go from the ignition of life through to complex life, the earliest that civilizations could have emerged on Earth is 220 million years ago. I'm going to conclude that natural selection requires 3.7Gyr before it can express creatures that are morphologically sophisticated enough to resemble humans. As an interesting aside, that doesn’t necessarily suggest that organisms could have evolved the cognitive capacity of humans at that time. For all we know, the mammalian brain requires the 200 million years of evolution and accumulated/refined DNA data to get to the sophistication it has today. I’ll admit, however, that that’s a stretch; time-to-evolve is not a fixed rate and is largely dictated by the severity of environmental stressors.
Using the 3.7Gyr metric, the earliest that complex humanoid life could have emerged in our universe is 4.72Gyr ago. That figure does not negate the Fermi Paradox. Given the potential emergence of intelligent life in our galaxy around that time, and given Fermi’s estimate that an ETI could colonize the galaxy within 10 million years, our galaxy could have been colonized nearly 500 times over by now.
Let’s try to whittle the figure down even further. Assuming that an advanced civ could have emerged on earth 220 million years ago, what would they have used to fuel their industrial revolution? Working under the assumption that fossil fuels are a necessary prerequisite for an industrial revolution to occur, how many years of accumulated biomass is required? By the same token, how much biomass is required to get to the Singularity?
Today, considering the threat of peak oil, we don’t know the answer to that question ourselves. We know that human civilization had enough to get to an industrialized phase of existence, but we don't actually know if we have enough energy to get to the Singularity (although I'm inclined to believe that we do).
Let’s assume here, however, that we have enough energy to make it. Vast forests of clubmosses (lycopods), horsetails, and tree ferns started to cover the land 300 million years ago – biomass that decayed and eventually formed coal and oil. Let’s use that as our metric for the time required to establish energy needs. That knocks our figure of 3.7Gyr down to 3.4Gyr – barely a dent.
I’m making an assumption, here – that the presence of oil and coal are a necessary condition for the emerge of radio-capable and pre-Singularity intelligences. I remember getting into a discussion with Eliezer Yudkowsky about this a number of years ago who begged to differ. He essentially claimed that 'where there’s a will there’s a way,' particularly given long enough time frames (I think he used the example of solar power).
I’m still unconvinced and would argue that fossil fuels are absolutely necessary. I'm going to use that in our calculation to push back the emergence of complex civs in the universe from 4.72Gyr ago to 4.42Gyr ago.
There are undoubtedly a plethora of factors I’m either omitting or exaggerating. The exact conditions required for the emergence of human-like intelligences may be more complex than it appears, and the universe may only be intelliphillic at this unique time (a violation of the Copernican Principle, I know, but one that should be considered; is the universe entering a phase transition?).
Formalizing my argument about when intelligences could first emerge in the universe, I'm going to use this as a starting equation:
[y.a. planets formed (P)] – [years it takes for life to emerge (L)] – [years it takes for DNA to become hominid-expressible (H)] – [years it takes to accumulate required biomass for energy (E)] = [y.a. radio-capable civs first emerged in the galaxy (A)]
P – L – H – E = A
Using my figures (in Gigayears):
9.1 – 0.6 – 3.78 – 0.3 = 4.42Gyr
So, it’s conceivable that Singularities and outward galactic expansions could have happened as long as 4.42 billion years ago. This is still an immense amount of time, keeping the Fermi problem deeply relevant.
So, where is everybody?
Tags: SETI, fermi paradox, drake equation, origin of life, astrobiology, astrosociobiology, cosmology, life on other planets, singularity.