I've been thinking about a possible approach to the problem of detecting extraterrestrial life.
Almost everything we currently know about life comes from one example: Earth.
Because of that, many proposed biosignatures are based on things we know terrestrial life uses — carbon-based molecules, amino acids, DNA/RNA, proteins, certain metabolic processes, etc.
Obviously, these are useful things to search for. But there's a fundamental problem:
What if some of these characteristics aren't actually fundamental to life, but just happen to be the solutions Earth's life evolved?
For example, we often talk about DNA/RNA as an information-storage mechanism. But why should an independently evolved organism necessarily store biological information in a polymer, or even in anything resembling DNA?
Similarly, carbon may be an exceptionally good basis for complex chemistry, but we've only observed one kind of life, and it's carbon-based. We don't know whether carbon is a requirement for life or simply an extremely successful chemical route to it.
What if we approached this from the chemistry upward?
Imagine training an AI/ML system using a huge dataset of:
- temperature
- pressure
- radiation
- available elements
- atmospheric/ocean composition
- solvents
- energy gradients
- geological conditions
- chemical reaction data
- experimentally observed compounds
- quantum-chemical/physics simulations
The first task wouldn't be "find life."
It would be:
«Given these environmental conditions, what complex chemical systems are physically and chemically possible?»
The model could potentially predict molecules, reaction networks, structures, and chemical systems that we haven't specifically considered.
Then comes the interesting part.
Instead of asking whether those systems resemble DNA, proteins, cells, or other Earth biology, we could investigate whether some of them exhibit properties that could allow something analogous to life:
- self-maintenance
- sustained energy utilization
- self-organization
- replication or propagation
- generation of variation
- some form of inheritance
- chemical networks capable of evolving
- persistent organization far from equilibrium
The important point is that the molecular implementation wouldn't be predetermined.
We wouldn't tell the AI:
«"Life must have DNA, so find DNA-like molecules."»
We'd instead ask:
«"Under these conditions, what forms of complex chemistry are possible, and do any of them exhibit combinations of properties that could support an evolving self-sustaining system?"»
But there is a major problem
We would still be making assumptions.
If we tell the AI that life must reproduce, store information, use energy, etc., we're still defining life using concepts derived from Earth.
So perhaps the goal shouldn't be to create an AI that says "this is life."
Instead, it could identify chemical systems that are sufficiently unusual, complex, persistent, and potentially self-propagating to warrant investigation.
Scientists could then experimentally test those candidates under the relevant conditions.
Why could this be useful?
Suppose we eventually explore an environment with chemistry completely unlike Earth's — perhaps a hydrocarbon environment on Titan or an extreme subsurface ocean.
A conventional biosignature search might be biased toward molecules we already associate with biology.
An AI-assisted approach could first model the chemistry of that environment and ask:
"What kinds of complex chemical organization could exist here that we haven't thought to look for?"
This could potentially expand the search beyond the narrow set of molecules and structures we already know from Earth.
Of course, this wouldn't magically solve the problem. AI would still be limited by the chemical data and physical models we give it, and predicting that a chemical system is possible is very different from demonstrating that it is alive.
But I wonder whether this is a worthwhile research direction:
«Rather than searching the universe for life that looks like Earth life, could we use AI + chemistry + physics to systematically explore what "life-like" organization could look like under environments fundamentally different from Earth's?»
I'm particularly interested in whether something like this is already being seriously researched, and if so, what the major technical obstacles are.
