The brief reply is sure, PoW is an indispensable element in blockchain.
First, let’s focus on whether or not Bitcoin’s proof-of-work-chain may be thought of a consensus mechanism.
The article proposing the Bitcoin community concludes with the concept that the “proof-of-work-chain” consists of two elements: the proof-of-work mechanism and the chaining course of. This mix may be seen as a consensus mechanism.
Nonetheless, Bitcoin’s proof-of-work mechanism doesn’t totally fulfill the ‘Settlement‘ situation required for consensus mechanisms.
In Bitcoin’s proof-of-work, short-term forks can happen, particularly in the course of the creation of recent blocks. Miners may discover legitimate options to the cryptographic puzzle concurrently, leading to competing legitimate blocks. This results in totally different elements of the community initially supporting totally different blocks.
Whereas the community finally converges to a single chain, and the longest-chain rule determines the canonical blockchain, there are transient durations when consensus isn’t unanimous, and totally different nodes may briefly help totally different blocks. This short-term fork phenomenon is inherent within the probabilistic nature of Bitcoin’s proof-of-work mechanism.
The talk on whether or not the mixture of proof-of-work and the chaining course of in Bitcoin constitutes a consensus mechanism stays unsettled. The Bitcoin community mechanism doesn’t fulfill all circumstances of a consensus mechanism, which embrace Termination, Uniform Integrity, Settlement, and Uniform Validity. [citation]
[citation] Kshemkalyani, Ajay D., and Mukesh Singhal. Distributed computing: ideas, algorithms, and methods. Cambridge College Press, 2011.
It is very important observe that the designers of the Bitcoin community proposed the ‘proof-of-work-chain’ as a consensus mechanism, implying the mixture of proof-of-work with the chaining course of, not proof-of-work alone.
Due to this fact, the early time period ‘proof-of-work-chain’ is likely to be extra correct than ‘blockchain,’ because it emphasizes the mixing of proof-of-work and the chaining course of. Separating these two components impacts the complete community, together with the effectiveness of the chaining course of with out proof-of-work.
With out PoW, the linked blocks may be fully changed by an altered chain. That is true whether or not there’s a lack of a Sybil or DoS assault prevention mechanism—akin to a sufficiently tough proof-of-work proportional to the entire hashing energy of the community—or in a permissioned community.
Within the absence of PoW, it’s attainable to switch the complete blockchain with a brand new legitimate one, the place all blocks are generated primarily based on the hash of earlier blocks, thereby creating and changing the present blockchain with a brand new legitimate chain.
Due to this fact, sure, PoW is an indispensable element in blockchain
A blockchain system with out PoW doesn’t make sense for stopping the alteration of transaction historical past.
That is regardless of Bitcoin’s proof-of-work-chain having its personal issues and inefficiencies, akin to consuming a considerable amount of vitality whereas processing solely 7 to 10 transactions per second.
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