In the future, there will be an Internet of chains, with bitcoin serving as the root chain for different applications such as factom / proofofexistence, ChainDB, Blockstream side chains, merge mined side chains, and more. A multi-chain design offers greater scalability in general. Mike Hearn argues that either everything must be validated or nothing at all, though probabilistic verification through validating a random subset of all scripts is possible. Side chains are not a means of scaling up. Jeff Garzik is a Bitcoin core developer and open source evangelist at BitPay, Inc.