51% attacks are commonly discussed where one entity could potentially mine blocks ahead of the network. The assumption is that the attacker manages to acquire 51% of computational power.

However, assuming that some entity manages to acquire much more computational power, and starting now over the next few years if it manages to exceed total amount of work, can they fork a complete new chain from the genesis block?
Hypothetical case, but purely according to the rule of longest chain by Total amount of work, isn't it possible that in future one could overcome the total amount of work done until now and invalidate current chain completely ?

1 Answer 1


It is possible only in theory. In practice that would require many times the world’s total energy output to pull that off not to mention the amount of hardware needed. And even if they could why would they and not just mine bitcoin?

  • > And even if they could why would they and not just mine bitcoin? .. That only, if they have a long position against BTC. An attacker who wants to destroy BTC (for example, a state actor) hat different incentives. Jun 21, 2021 at 12:47
  • Even if they do, once people know about it, they can simply choose to ignore that miner and fork. It would be pretty obvious I think
    – noone392
    Jun 21, 2021 at 14:51
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    @noone392 note that there is no way to 'choose to ignore an attacking miner', without hardforking to a consensus mechanism other than SHA256 (aka, creating a new network).
    – chytrik
    Jun 21, 2021 at 19:56
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    Right but you can choose a branch. Inguess that still counts as a different concensus mechanism but " all good miners just agree that this block's hash doesn't count" still a hard fork but no need to change ge the actual algorithms
    – noone392
    Jun 22, 2021 at 4:51

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