  The multifarious internal workings of organisms are difficult to reconcile
with a single feature defining a state of being alive. Indeed, definitions of
life rely on emergent properties (growth, capacity to evolve, agency) only
symptomatic of intrinsic functioning. Empirical studies demonstrate that
biomolecules including ratcheting or rotating enzymes and ribozymes undergo
repetitive conformation state changes driven either directly or indirectly by
thermodynamic gradients. They exhibit disparate structures, but govern
processes relying on directional physical motion (DNA transcription,
translation, cytoskeleton transport) and share the principle of repetitive
uniplanar conformation changes driven by thermodynamic gradients, producing
dependable unidirectional motion: heat engines exploiting thermodynamic
disequilibria to perform work. Recognition that disparate biological molecules
demonstrate conformation state changes involving directional motion, working in
self-regulating networks, allows a mechanistic definition: life is a
self-regulating process whereby matter undergoes cyclic, uniplanar conformation
state changes that convert thermodynamic disequilibria into directed motion,
performing work that locally reduces entropy. Living things are structures
including an autonomous network of units exploiting thermodynamic gradients to
drive uniplanar conformation state changes that perform work. These principles
are independent of any specific chemical environment, and can be applied to
other biospheres.
