| The essential prediction is that complex things are made by some sort of repeatable assembly process/factory, not by chance (with increased confidence when multiple copies have been seen). There is an idea of an "assembly index" for objects (e.g. molecules) as a measure/bound of how many steps they took to assemble - the level of complexity. There is also a prediction (or definition?) that things with a high assembly index are produced by some form of life, so if one can measure the assembly index of molecules and find ones of high index/complexity, then this indicates they were created by some form of life, and so this can be used as a test for life without having to make any assumptions of it being like life on earth (and therefore only looking for biosignatures of life we know of). Assembly theory seems most interesting when applied to molecules, although it's not limited to that in scope. There are constraints on how complex molecules are formed in terms of what reacts with what, as well as some intuitive measure of complexity in terms of their size and variety of components and atomic bonds. One thing that Lee Cronin has discovered/noted is that mass spectrometry can be used as a crude way to measure complexity of molecules, and hence give an idea of their "assembly index", since different chemical bonds have different fingerprints in terms of how they absorb energy (diff. frequencies of UV or IR light absorbed in the mass spec.). There's a couple of different applications of this use of mass spectroscopy as a proxy for assembly index that Cronin mentions in his interview with Lex Fridman, which do seem to provide some proof of it's predictions of high assembly index being an indicator of life, and relative assembly index and indicator of which came first. 1) NASA, wanting Cronin to prove the value of this as a potential life-detector, gave him a variety of unlabeled organic and inorganic samples, and Cronin was able to classify them all correctly based just on their mass spec. signatures. 2) By analyzing a variety of biological samples, again via his mass spec. technique, Cronin was able to reconstruct the evolutionary tree of life in agreement with other ways of doing this. He goes into a little detail on the Lex interview, but it sounds complex and he does not fully describe the technique/analysis. |