Take a look at your hands. In them, you find atoms that once belonged to stars dead more than 5 billion years ago. Those stars, bigger than our sun, forged much of the chemistry of life during their last moments, before exploding into giant supernovae. They forged chemical elements spread through the interstellar medium, collecting here and there in self-gravitating hydrogen clouds. Occasionally, these clouds would become unstable to their own gravity and contract. These contracting nebulae gave rise to stars and their orbiting planets, trillions of them in our Milky Way alone. In at least one of them, elements combined in incredibly complex ways to create living creatures. And of these myriad beings, one developed mind, the ability to sustain complex thoughts and to wonder about its origins.
We are, in a very real sense, self-aware stardust.
Amazingly, all the stars had to start with was hydrogen and gravity. As gravity compressed the hydrogen gas to enormous pressures, hydrogen fused into helium, climbing the first step of the chemical ladder. For most of their life, stars kept this fusion process on. As they ran out of hydrogen in their core, they started fusing helium into carbon, then oxygen and nitrogen, and so on all the way to uranium. That's what stars do, they make chemical elements.
In the modern scientific view, we are what happens when you give hydrogen and gravity a few billion years.
There are many gaps to fill in this cosmic narrative, and this is what makes science exciting. As we thrust ahead, we learn more about the universe and our place in it. Perhaps one of the most controversial questions that follows from this discussion concerns our inevitability. Is our existence an inevitable consequence of the laws of Nature? Or are we an accident, and the cosmos could equally well exist without us?
The hard line scientific position would answer that all we can do is explain what we measure. There is no purpose or plan, just what happens. And what we measure tells a story that starts at least with quarks (the particles that make up protons and neutrons), electrons, and radiation, and ends, a few billions later, with life and humans. As we move on from the early universe populated with quarks one-millionth of a second after the big bang to the star-studded cosmos of today, there is no question that matter became more “complex,” in the sense that more complicated structures arose as time went by. I don’t think anyone in his/her right mind would argue that a cosmos filled with a soup of elementary particles and radiation is less complex than one filled with stars, planets, and people. So, we see a connection between the arrow of time and the increase in complexification of the natural world. Why?
Before venturing down this road, we should pause for a second and contemplate the beauty of this achievement. We humans have come to understand, at least in part, this grand epic of creation from its origins to today. And what we’ve learned speaks of our deep connection with the cosmos, not just because we live in it but because we are made of it. If we are bits of star stuff— as is any other aggregation of matter across space—we are one with the cosmos: we are in the cosmos and the cosmos is in us.
Whoever doubts that science is a deeply spiritual endeavor should reflect upon this. The very concrete data gathering and theorizing that are the trademarks of science and that make up most of a scientist’s everyday activities are all part of this quest. Some may stop there and not bother to look around, and that’s fine. But if you do take a step back and lift your head, the truth is obvious for all who want to see it:
Science responds to the same spiritual need for meaning that has been with us since the dawn of humanity.
So, if we return to our existence and ask if we are inevitable, what can we say? Yes, there is an obvious increase in complexification as you go from quarks to mind. And yes, there could be a hidden principle out there explaining why this is so. But could it have been otherwise, that is, could the universe and, in particular, life on Earth, have developed so that we wouldn’t be here? From what we know now, the honest answer is yes. If we look at the way in which life evolved here at least, we see contingency playing a big role: change this or that cosmic event, and life would have taken another turn. Dinosaurs were here for 150 million years and were doing fine until the big rock came from the sky and killed them. Before the dinosaurs, for the first 3 billion years, life here was mostly bacteria. So, it’s hard to state with confidence that there is an imperative for complex intelligent life to exist in the universe. (Although many do.) On the other hand, even if we don’t think there is an imperative for our existence, we are here, products of 13.7 billion years of cosmic evolution. And that is a fact.
How you choose to respond to this question tells much about who you are and what you believe in. If you think there is some kind of cosmic teleology, a sense of purpose that inevitably leads to life, you are saying we are inevitable. If you don’t, if you say we are the result of a series of cosmic accidents, then for you believe we aren’t inevitable. We just happened. This latter position is often accused of being nihilistic: if we are the results of accidents, what’s the point of being alive?
Well, since we presently lack a principle explaining our inevitability, I’d argue that precisely because we are the result of accidents we are very important. We don’t have to be the result of a grand plan to have a sense of purpose. Going further, I’d claim that our purpose comes from our rarity, from the fact that at least as far as we know we are the only beings capable of thinking about our existence. So, the point of being the result of an accident and yet being alive and intelligent is to celebrate and protect that what made us possible: our universe and our planet. Until we find a principle explaining our cosmic inevitability, this gives me plenty to work with.