4. Can future aging states be reliably predicted?

At fine resolution, a non-biological aging trajectory is largely unpredictable: to know exactly what will happen you would, in effect, have to let the system age, because the future depends on an enormous web of interacting processes with stochastic micro-events. This puts a bound on the prediction power (and on the possibility that a single biomarker can fully summarize a future of that system). However, useful predictions are possible in biological aging, because biology contains many evolved functions that behave reproducibly at the scales we can measure, and therefore produce more predictable deleteriomes. Practically, this means biological aging predictions are only partially probabilistic and conditional, and partially quite predictable, as illustrated by using aging clocks.