"The empty block attack is one where a majority of mining power would be directed at mining only empty blocks and rejecting non-empty blocks. These miners would essentially execute a soft-fork where all non-empty blocks would be rejected. Given that they have a majority of hashing power on the network, so the thinking goes, they will eventually get the longer chain even if other miners were to mine non-empty blocks. If only empty blocks are being mined, all activity on the network would stop and so, the thinking goes, Bitcoin would be killed." - Jimmy Song