We've detected 6000+ exoplanets, but are we even searching for life the right way?
We search for biosignatures based entirely on what we know: carbon, liquid water, oxygen, temperatures compatible with our biochemistry. But that's just one data point — life on Earth. We have zero alternative examples.
Which raises the question: are we searching for life, or are we searching for copies of ourselves?
In 2023, the James Webb Space Telescope detected possible traces of dimethyl sulfide in the atmosphere of K2-18b — a compound that, on Earth, is only produced by living organisms. It's not confirmed, but it's not dismissed either.
Meanwhile, researchers like Lee Cronin and Sara Walker are working on Assembly Theory, an attempt to define and detect life based on chemical complexity rather than specific biochemistry — which could theoretically identify life that looks nothing like ours.
Fiction has been playing with this for years: the astrophage in Project Hail Mary, the Na'vi's biological network in Avatar, even the energon-based Transformers. All fictional, but all pointing at the same idea — life doesn't have to work the way ours does.
So my question is genuine: given that our instruments are calibrated to detect our kind of life, how confident can we actually be that none of those 6,000+ exoplanets host something alive? And what would it even take to detect life we don't recognize as life?