Is Life Inevitable?

🌍 Two Stories About Life

There are two ways to explain why we're here, and they couldn't be more different.In the first, life is what matter does when it gets water, energy, and time – almost a chemical inevitability, so the universe should be quietly full of it. In the second, life is an absurd fluke – a one-off accident so unlikely it may have happened only here, and we exist simply because in an endless universe even near-impossible things occur somewhere. What gets me is that two completely opposite answers to such a basic question are both still wide open – nobody can rule either one out.

🪤 Why the Question Is a Trap

There's a hidden catch in asking it. We have exactly one example of life – ours. And we could only ever find ourselves on a planet where life did appear. So even if life is wildly rare, every observer who exists will look around and see life and feel like it must be common.That's why the usual argument – "life showed up on Earth pretty fast, so it must be easy" – is weaker than it sounds. Of course it looks easy from inside the one place it worked. With a sample size of one, we're nearly blind.

🧬 From Chemistry to Life

The hardest part of the puzzle isn't life evolving once it exists – it's life starting: how plain chemistry first became something that copies itself. The idea that finally made it click for me is the self-replicating molecule. Reading Dawkins' The Selfish Gene, it just fit: once a molecule appears that can copy itself, even badly, the copies that happen to survive and replicate best simply pile up. Chemical evolution slides into biological evolution with no magic moment in between. For me that's still the most convincing bridge from dead matter to life.

☄️ Maybe the Ingredients Are Common

What nudges me toward "life is common" is how easily its raw materials turn up off Earth. Amino acids – the building blocks of proteins – have been found in meteorites, and even detected streaming off a comet. And bacteria have survived years bolted to the outside of the Space Station, in raw vacuum and radiation, the dead outer cells shielding the living core. So the ingredients are scattered everywhere, and life is tougher than it looks.And it isn't only at the edge of space. Right here on Earth we keep finding life everywhere we assume it couldn't possibly be: kilometres down inside solid rock, frozen into glaciers, thriving in acid lakes that would dissolve us, even drifting as microbes through the fog and clouds of the atmosphere. There's barely a corner harsh enough to keep it out. The more we look, the more it seems life isn't fragile and picky but stubborn, adaptable, and quick to colonize anything – which makes it feel far less like a rare miracle and far more like something that takes hold wherever it gets half a chance.Then comes the flip side – the Fermi paradox: if life is so likely, where is everybody? The sky is silent. Maybe simple life really is everywhere, and what's actually rare is the leap to complex, intelligent life – not life itself that's scarce, but minds. Or maybe they're out there and we just haven't heard them yet. We don't know.

🔁 Replay the Tape

This is the same question I ask about the whole universe in Would It Happen Again?, just shrunk down to life: if we re-ran evolution from the start, would we get anything like this again?What makes me lean toward "yes, roughly" is how often nature arrives at the same answer twice. Eyes were invented independently many separate times; so were wings, and the streamlined body shape of fast swimmers. Biologists call this convergent evolution, and it suggests evolution isn't wandering an endless space of possibilities – there are only a few good solutions, and the rules keep funneling life toward them. Maybe even intelligence is one of those destinations.

🧪 Could We Answer It Without Leaving Earth?

What I keep turning over is whether there's a way to settle this without scanning the skies for someone else at all – an experiment run entirely here on Earth that still gives an answer. A few shapes seem possible:

• Run thousands of tiny young-Earths in parallel jars and see whether self-copying chemistry appears again and again, or basically never.
• Run evolution in software from random starts, millions of times, and watch whether the same kinds of solutions – even intelligence – keep emerging.
• If the same outcomes recur across independent runs, life is a destination. If they almost never do, we really are a fluke.

❄️ Snowflakes and Rivers

The image I keep landing on is a snowflake and a river. No two are identical, yet they all share a structure – six arms, a branching delta – because the underlying rules force it. The details vary; the shape does not.Maybe life is like that. The exact species, the exact me, would never repeat. But something alive, organizing itself and reaching toward complexity, might form every time, because the rules quietly favor it – life as what matter leans toward when energy flows through it, the thread I pull in Life Against Entropy.And yet I can't fully close the question, because it leans on the one I still can't answer: whether anything is truly random at all. If re-running reality could land somewhere new, life might be a coin toss that came up heads. If reality only ever unfolds one way, then life was never probable or improbable – it was simply always going to be here. Until I know that, I can't really know this.