The Ethereum Layer 2 project Plasma yesterday introduced the Optimistic Virtual Machine (OVM) on Medium, a virtual machine that supports all Layer 2 protocols. Its versatility comes from repositioning Layer 2 as an optimal fork selection mechanism based on the Ethereum protocol. The OVM specification draws heavily on the CBC Casper Consensus Protocol paper and describes Layer 2 as a direct extension based on the Layer 1 consensus. This provides the possibility to unify all Layer 2 protocols (Lightning Network, Plasma, etc.) through a virtual machine OVM.