Bitcoin developer Robin Linus has released "BitVM2", a revamped version of last year's "BitVM" paradigm that aims to boost Bitcoin's programmability and push the concept closer to real-world applications. "BitVM2" introduces a "permissionless challenge" feature that allows anyone to question suspicious transactions, addressing key deficiencies in the original. The project creates a secure "bridge" that enables Bitcoin to move from the main network to the "rollups" secondary network and eventually back to the main network by using advanced cryptography and a new design. Linus' project is seen as a breakthrough for not requiring changes to Bitcoin's underlying code. The new design simplifies bridge operations, increases capital efficiency, and is expected to bring broader application prospects to the Bitcoin ecosystem.