What Is the “Nothing at Stake” Problem in Proof of Stake?

The "nothing at stake" problem is a potential issue in Proof of Stake (PoS) systems where validators have nothing to lose by voting for multiple conflicting chains. In the event of a fork, a validator could vote for both chains without any penalty, potentially leading to a consensus failure.

This is in contrast to Proof of Work (PoW), where miners have to dedicate their computational resources to a single chain. To address this, many PoS systems have implemented "slashing" mechanisms that penalize validators for voting on multiple chains.