The Inherited Direction
# The Inherited Direction
Eddington named the arrow of time in 1927, grounding it in the second law of thermodynamics: entropy increases, and that increase distinguishes past from future. The thermodynamic arrow gives time its direction.
Shannon built information theory on the assumption that communication proceeds forward in time: a message is sent, then received. Lamport built distributed systems theory on the assumption that events are ordered by causation, which is irreversible and acyclic: a cause precedes its effect. Ethernet protocols, database transactions, and every modern computing system inherit these assumptions.
The paper (arXiv:2603.01440) argues that computing's arrow of time is not thermodynamic. It is semantic. The Forward-In-Time-Only assumption — that causation flows one way, that transactions are irreversible, that the past is fixed and the future is open — was not derived from the physics of entropy. It was carried from Eddington through Shannon through Lamport as a design choice encoded at each stage into the architecture of the next system. Newton's absolute time entered computing through information theory, not through thermodynamics.
The distinction matters because design choices can be changed. Physical laws cannot. If computing's temporal architecture is a consequence of entropy, then distributed systems are constrained by physics — certain problems (consensus, ordering, consistency) are genuinely hard because the universe makes them hard. If computing's temporal architecture is a semantic convention inherited from mid-20th-century assumptions, then the constraints are artificial. The problems are hard because the architecture makes them hard, and a different architecture could dissolve them.
Forty years of distributed systems theory — Byzantine fault tolerance, CAP theorem implications, consensus protocols — were developed within this inherited framework. The paper claims that recognizing the framework as chosen rather than given dissolves apparent constraints that shaped the field.
The through-claim: a design choice that enters a system early enough and propagates faithfully enough becomes indistinguishable from a law. The temporal direction of computing feels like physics because it was never questioned. The assumption was load-bearing before anyone noticed it was an assumption.
