BITCOIN RAILS EPISODE #19: Cracking The Bitcoin Bridging Problem | with Alexei Zamayatin @alexeiZamyatin @build_on_bob was one of the first Bitcoin L2s to hit the scene after Ordinals made Bitcoin an investable “utility” category and @robin_linus BitVM paper took the Bitcoin developer world by storm. Shortly after the publication of BitVM, BOB founder @alexeiZamyatin pivoted sharply into Bitcoin L2s after having previously “given up” on the idea that Bitcoin could integrate trustless bridges of any kind. “My entire PhD thesis was focused on building trustless bridges for Bitcoin… our conclusion was that trustless bridging was impossible” …until BitVM came along. After meeting BitVM author @robin_linus on @TheOrdinalShow (fun fact!) and falling down the BitVM rabbit hole, Alexei eventually became co-author of the BitVM2 paper, helping optimize original ideas of BitVM for trust-minimized bridging. In this episode, Alexei and I chat about: The history of developing bridges for scaling—starting with Adam Back’s introduction of sidechains, to early “roll up” models like commit chains, and other early architecture. Why building trustless bridges in any ecosystem was widely considered impossible - and which “practical solutions” academics were focused on before BitVM. How BitVM2 optimizes BitVM for bridging—and the “electric” developer culture that spawned the current Layer 2 landscape in Bitcoin. Why BOB takes a different approach to scaling than other BitVM-style projects—and why it’s “hybrid” model may be most realistic for scaling. Additional shout outs in the episode to: @TO @SuperTestnet @JeremyRubin @robin_linus As always, you can watch this episode on YouTube or Spotify—linktree in my bio + full episode in the comments. This episode is powered by Best In Slot—the leading API for Ordinals and BRC20 data aggregation and indexing. TIMESTAMPS: 1:50 How did BOB come to be? 4:28 How early was the “Bitcoin L2” conversation? 5:45 The problem with merged mining 11:40 Alexei’s growing interest in Bitcoin DeFi 13:17 Never a fan of lightning 15:00 The Blocksize Wars begin 17:00 Academic early research on “distributed systems.” 19:40 Bitcoin’s “dark age” after SegWit 20:30 Alexei’s super early work on “trustless” bridging 22:10 Alexei’s PHD: Trustless bridging is impossible 25:00 Pre BitVM bridging solutions 28:40 Alexei’s work on Polkadot and intro to ZKPs 32:50 Ethereum is hard to verify 34:35 Starting work on BOB 38:50 The Hybrid Consensus: Merged Mining and Ethereum Rollups 42:25 How BitVM derailed Alexei’s plans 47:00 Working with Robin Linus on a ZK bridge 49:35 SNARKs vs STARKs 50:35 The limitation of BitVM, how we’ve improved it 52:30 BitVM: Making challenging proofs permissionless 55:50 The challenge / response game of BitVM 59:55 BitVM2: Splitting programs to fit into Bitcoin blocks 01:03:00 Competition in the BitVM design space 01:05:00 Focusing on BOB, leaving BitVM to Fiamma 01:07:00 BOB is an “interoperable execution environment” 01:09:00 Build in isolation; get liquidity fragmentation 01:10:30 Is BOB the most secure Bitcoin L2? 01:13:05 How BitVM makes Babylon staking more secure 01:17:50 “Trust minimization dick measuring”