How proof work prevents rebuilding of blockchain

Question

In proof of state, nonce is not that hard to found. So is it possible to tamper a block and rebuild subsequent blockchain? Or proof of stake has some other way to prevent this?

Answer 1

POS has the same idea as POW. The difference is, instead of computational (CPU/GPU) power, in POS the miners that own the most number of coin would have the power to make changes in the chain. To attack a blockchain network based on POS, the attacker will need to acquire more than 50% of all the coins in circulation.