This is the first of five papers comprising The Semantic Arrow of Time. The argument begins with a claim: computing's arrow of time is semantic, not thermodynamic. The direction in which meaning is preserved or destroyed across transactions is not a consequence of the second law but of design choices embedded in protocol architectures since Shannon's 1948 channel model. These choices encode the Forward-In-Time-Only (FITO) assumption -- the commitment that causation is irreversible, acyclic, and globally monotonic. We trace this assumption from Eddington's 1927 coinage of "the arrow of time," through the Boltzmann--Loschmidt debate, to contemporary philosophy of physics: Price's time-symmetric ontology, Smolin's temporal naturalism, Rovelli's relational quantum mechanics, and Roberts's analysis of time-reversal symmetry. We show that fundamental physics is time-symmetric at the microscopic level, that the thermodynamic arrow emerges from boundary conditions rather than fundamental law, and that recent demonstrations of indefinite causal order confirm nature admits correlations with no well-defined temporal ordering. We then identify the category mistake (Ryle, 1949): computing inherited Newton's absolute background time -- via Shannon, Lamport, and the impossibility theorems -- and encoded it as a semantic primitive. The FITO assumption is not a law of nature but a design choice, and recognizing this dissolves apparent constraints that have shaped forty years of distributed systems theory. Subsequent papers develop the constructive alternative through link semantics, RDMA, transaction failures, and the Leibniz Bridge framework.

翻译：本文是《语义时间之箭》系列五篇论文中的首篇。论证始于一个主张：计算的时间之箭是语义的，而非热力学的。意义在事务中得以保存或销毁的方向，并非第二定律的结果，而是自香农1948年信道模型以来，内嵌于协议架构中的设计选择。这些选择编码了“仅向前时间”（FITO）假设——即因果性不可逆、无环且全局单调的承诺。我们追溯这一假设，从爱丁顿1927年创造“时间之箭”这一术语，历经玻尔兹曼-洛施密特争论，直至当代物理学哲学：普赖斯的时间对称本体论、斯莫林的时间自然主义、罗韦利的关系量子力学，以及罗伯茨的时间反演对称性分析。我们表明，基础物理学在微观层面是时间对称的，热力学时间之箭源于边界条件而非基本定律，并且近期关于非定因果序的演示证实，自然界允许不存在明确定义时间顺序的关联。随后，我们指出了范畴错误（赖尔，1949）：计算继承了牛顿的绝对背景时间——经由香农、兰波特及相关不可能性定理——并将其编码为语义原语。FITO假设并非自然法则，而是一种设计选择；认识到这一点，便可消解那些塑造了四十年分布式系统理论的表面约束。后续论文将通过链接语义、RDMA、事务故障以及莱布尼茨桥框架，发展出建设性的替代方案。