PoW is Efficient

Many people believe that Bitcoin's Proof of Work (PoW) mechanism "wastes electricity". I think I should explain to everyone: actually everything is energy, currency is also energy, and the evaluation of energy is subjective. In the end, how does PoW's energy consumption compare to existing regulatory systems like ours? This article blends original thoughts from many people in the community — what I've done is merely to aggregate, refine and combine these perspectives.