Tag: Turing machines

Searching for Emergence

Mark Davis1 Comment

I have a longstanding interest in the concept of emergence as a way of explaining a wide range of human ideas and the natural world. We have this incredible algorithm of evolutionary change that creates novel life forms. We have, according to mainstream materialist accounts of philosophy of mind, a consciousness that may have a unique ontology (what really exists) of subjective experiencers and qualia and intentionality, but that is also somehow emergent from the meat of the brain (or supervenes or is an epiphenomenon, etc. etc.) That emergence may be weak or strong in various accounts, with strong meaning something like the idea that a new thing is added to the ontology while weak meaning something like we just don’t know enough yet to find the reduction of the concept to its underlying causal components. If we did, then it is not really something new in this grammar of ontological necessity.

There is also the problem of computational irreducibility (CI) that has been championed by Wolfram. In CI, there are classes of computations that result in outcomes that cannot be predicted by any simpler algorithm. This seems to open the door to a strong concept of emergence: we have to run the machine to get the outcome; there is no possibility (in theory!) of reducing the outcome to any lesser approximation. I’ve brought this up as a defeater of the Simulation Hypothesis, suggesting that the complexity of a simulation is irreducible from the universe as we see it (assuming perfect coherence in the limit).

There is also a dual to this idea in algorithmic information theory (AIT) that is worth exploring. In AIT, it is uncomputable to find the shortest Turing Machine capable of accepting a given symbol sequence.… Read the rest

Find the Alien

Mark Davis2 Comments

Assembly Theory (AT) (original paper) is some new theoretical chemistry that tries to assess the relative complexity of the molecular underpinnings of life, even when the chemistry might be completely alien. For instance, if we send a probe to a Jovian moon and there are new microscopic creatures in the ocean, how will we figure that out? In AT, it is assumed that all living organisms require a certain complexity in order to function since that is a minimal requirement for life on Earth. The chemists experimentally confirmed that mass spectrometry is a fairly reliable way of differentiating the complexity of living things and their byproducts from other substances. Of course, they only have Earthly living things to test, but they had no false positives in their comparison set of samples, though some substances like beer tended to be unusually high in their spectral analysis. The theory is that when a mass spec ionizes a sample and routes it through a magnetic and electric field, the complexity of the original molecules is represented in the complexity of the spray of molecular masses recorded by the detectors.

But what is “complexity” exactly? There are a great number of candidates, as Seth Lloyd notes in this little round-up paper that I linked to previously. Complexity intuitively involves something like a trade-off between randomness and uniformity, but also reflects internal repetition with variety. There is a mathematical formalism that in full attribution is “Solomonoff-Chaitin-Kolmogorov Complexity”—but we can just call it algorithmic complexity (AC) for short—that has always been an idealized way to think about complexity: take the smallest algorithm (in terms of bits) that can produce a pattern and the length of the algorithm in bits is the complexity.… Read the rest