The foundation of quantum mechanics is Heisenberg's Uncertainty Principle. And the root of the Uncertainty Principle lies in the generation process of quantum motion, caused by the non-commutative self-reference. The consensus mechanism of $BTC is exactly the same logic. The longest chain exhibits quantum properties—it is dynamically generated and never 100% confirmed. The root cause lies in the non-commutative nature of the transaction order during the generation process of the longest chain. Transaction order is the only consensus principle of $BTC. The higher the certainty of the longest chain, the longer the historical confirmation time. In other words: the position of the longest chain and its momentum (the block currently being mined on the longest chain) are a pair of non-commutative conjugate variables.