Do u really need more than %50 mining power in order to attack bitcoin blockchain? my question is about concept, so code is not related, however, do you really need %51 of the mining power in order to attack/replace the real bitcoin Blockchain? For example, a blockchain has a length of 8, A, B, C, D, E each represent a individual with %20 of the total mining power, lets say person A and B decide to work together, but that's only %40 of the total mining power(less than %51), for illustration purpose, miner C, D, E will always mine alone, so by the time miner C, D, E each finished mining the 9th block, A and B have already mined the 11th block(assuming they mine faster, since they work together and have a total mining power of %40), so longest chain wins right? and now the 9th block that miner C, D, E just mined becomes invalid and their chain will be replaced to the longer blockchain, does this mean A and B might have the power to control and manipulate the entire bitcoin Blockchai