
Lux(λ) |光尘|空灵|GEB|May 21, 2025 02:42
The concept of the "world computer" model faces fundamental challenges, with the core being the limitations of the Turing machine itself. What we usually refer to as' Turing completeness' only means the completeness of all computable data defined by Turing. However, to build a truly secure and reliable adaptive complex system, computable completeness alone is far from enough.
Beyond the completeness of 'computability'
A sound adaptive system must have the ability to handle both computable and non computable problems simultaneously. The term 'uncomputable' here does not refer to problems that cannot be solved by algorithms, but rather to those that rely on external interactions, game decisions, or unpredictable human behavior beyond formal logic. These 'uncomputable' characteristics are the key to maintaining robustness and resilience of the system in an open and dynamic environment.
The manifestation of 'uncomputable': P/NP and asymmetric interaction
The exploration direction of 'uncomputable' can be extended to asymmetric interactions in P/NP problems in computer science. The P problem represents a problem that is easy to compute and verify, while the NP problem represents a problem that is easy to verify but extremely difficult to compute. Asymmetric encryption in cryptography utilizes this computational asymmetry: encryption is easy, decryption is extremely difficult, thus ensuring information security.
In a complex system, this' uncomputable 'property is manifested through asymmetric interactions. For example, the cost of attacking a system (which may involve solving an 'uncomputable' problem) is much higher than the cost of normal use and validation (solving a 'computable' problem). It is precisely this computational asymmetry that provides important guarantees for the security and reliability of the system.
Bitcoin: The First Artificial "(computable+non computable) Complete" System
Based on this, Bitcoin can be regarded as the first artificial adaptive system in human history that satisfies both computable and uncomputable completeness.
The computable part: The core operations of Bitcoin, such as transaction verification, hashing, and block propagation, are all based on rigorous and predictable algorithms, making them typical "computable" tasks.
The non computable part (reflected through P/NP asymmetric interaction): The emergence of the longest chain: The formation of Bitcoin's longest chain is not purely a result of computation, but rather a product of miners' game in P/NP asymmetric interaction. Finding a valid hash value is an "uncomputable" problem (NP problem), while verifying its correctness is a "computable" problem (P problem). The competition for computing power, strategic choices, and expectations for future rewards among miners all contain elements of "non computability", ultimately leading to the consensus of the longest chain. UTXO and human-computer interaction: The UTXO (Unspent Transaction Output) model of Bitcoin also reflects the asymmetry of P/NP and is closely related to human-computer interaction. Generating a new UTXO (i.e. initiating a transaction) involves digital signature and other operations, which are relatively complex, while verifying the validity of the UTXO is relatively simple. Users interact with UTXO through tools such as wallets, and this interaction itself contains "incalculable" factors, such as users' subjective decisions, risk preferences, etc.
Therefore, if a "world computer" model cannot generate or effectively handle the "uncomputable" characteristics brought about by asymmetric interactions within it, it cannot truly construct the Bitcoin network, nor can it claim the universality of its theory. The success of Bitcoin lies in its ability to surpass the computational boundaries of traditional Turing machines, cleverly blending computability and non computability, achieving true security and adaptability.
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