Here is a problem that has been quietly gnawing at astronomers for decades.
The standard approach to detecting #life on other worlds involves scanning #exoplanet #atmospheres for #oxygen, #methane, and #ozone, whose presence is difficult to explain without #biology.
It's a clever idea, but it carries a hidden flaw. That entire shopping list was written by studying Earth. It is, inevitably, a search for life like us.
The list of ways that #chemistry alone can accidentally mimic these #biosignature gases is growing faster than the list of new ways to detect life.
Each new false positive scenario demands even more information about the #planet to rule it out, and there is a genuine question about whether that information can ever be gathered exhaustively.
But there is a solution.
#Assembly theory doesn't ask what #molecules are present in an #atmosphere. Instead, it asks how hard they were to make.
Every molecule can be assigned an assembly index, a minimum number of construction steps required to build it from basic #chemical building blocks.
Simple molecules are easy to assemble by chance, but truly complex ones, requiring many sequential steps, don't arise without something doing a great deal of deliberate selection.
That something would then be life itself.
#astrobiology #astronomy
https://phys.org/news/2026-03-life.html
Paper by Walker et al. (2026): https://arxiv.org/abs/2603.11086