The second Scaling Bitcoin workshop convened in Hong Kong on December 5-6, 2015, bringing together the brightest minds in Bitcoin development and mining to address the network’s most pressing challenge: scalability. With Bitcoin trading at approximately $389 and the block size debate reaching a fever pitch, the stakes had never been higher for the young cryptocurrency ecosystem.
TL;DR
- Scaling Bitcoin Phase II gathered core developers and miners controlling ~80% of network hashing power in Hong Kong
- Adam Back of Blockstream emphasized fungibility as a core Bitcoin property that needs urgent improvement
- Peter Todd advocated for a cautious approach to scaling, pointing to Lightning Network as a promising off-chain solution
- A landmark mining panel featured seven major mining operations discussing BIP proposals and network governance
- Zero-knowledge proofs were presented as a potential long-term scalability breakthrough
A Gathering of Bitcoin’s Power Players
The Hong Kong workshop represented a critical moment in Bitcoin’s young history. The cryptocurrency had spent much of 2015 trading between $200 and $400, a far cry from the heady days of late 2013 when it briefly touched $1,000. But beneath the relatively stable price action, a fundamental disagreement was tearing the community apart: how should Bitcoin scale to handle more transactions?
The block size debate had been simmering for months. Bitcoin’s original 1MB block size limit was increasingly seen as a bottleneck, with transactions sometimes delayed and fees creeping upward. Some advocated for a simple block size increase through proposals like BIP 101, while others warned that such changes could centralize the network by making mining prohibitively expensive for smaller operators.
Adam Back and the Fungibility Question
Blockstream president Adam Back opened the workshop with a presentation that went beyond mere block size discussions. He argued that fungibility — the property that makes individual bitcoins interchangeable and equal — was under threat and deserved immediate attention from the development community.
Back told the audience that fungibility was essential for any electronic cash system and that all Bitcoin users would face problems if it disappeared. He explored privacy-enhancing technologies like CoinJoin and Zerocash implementations as potential solutions, positioning fungibility improvements alongside scaling work as essential to Bitcoin’s long-term viability.
Zero-Knowledge Proofs Enter the Conversation
Researcher Madars Virza presented a fascinating talk on zero-knowledge proofs and their potential application to Bitcoin scalability. His presentation, titled “Zero-knowledge proofs for Bitcoin scalability and beyond,” offered a technical deep dive into how cryptographic proofs could allow the network to verify transactions without revealing underlying data — a concept that would later become central to privacy coins and layer-2 solutions.
Virza urged attendees to keep zero-knowledge proofs on their radar, arguing that anyone concerned with Bitcoin’s scalability should care about this emerging technology. At the time, the idea seemed theoretical to many in the room, but it would prove prescient as zk-SNARKs and zk-rollups became fundamental to blockchain scaling years later.
Peter Todd’s Cautious Approach
Perhaps the most provocative presentation came from developer Peter Todd, who argued against rushing to implement scaling solutions. Todd advocated for a “wait and see” approach, suggesting that small, incremental code changes over time were preferable to dramatic block size increases.
Todd argued that adversarial environments required better technology rather than simple workarounds. He pointed to the Lightning Network as an example of how off-chain solutions could address scalability without compromising Bitcoin’s core architecture. He noted that Lightning’s design meant mistakes don’t build on each other and users could always verify the consensus blockchain.
The Mining Panel: 80% of Hashing Power Speaks
The workshop’s most anticipated session was a mining panel featuring seven of the largest mining operations in the world, collectively representing approximately 80% of Bitcoin’s total hashing power. Panelists included Sam Cole of KnCMiner, Alex Petrov of BitFury, Liu Xiang Fu of Avalon, Wang Chun of F2Pool, Robin Yao of BW, Pan Zhibiao of Bitmain, and Marshall Long of FinalHash.
The panel discussed various BIP proposals and the mining industry’s perspective on the block size debate. Their collective input carried enormous weight — any scaling solution would ultimately require miner support to implement. The discussion highlighted the growing professionalization of Bitcoin mining, which had evolved from a hobbyist activity into a multi-million dollar industry with significant capital investments in specialized hardware.
Why This Matters
The Scaling Bitcoin Hong Kong workshop captured a pivotal moment in cryptocurrency history. The debates held in that room — block size versus layer-2 solutions, on-chain versus off-chain scaling, developer vision versus miner preferences — would shape Bitcoin’s development for years to come. The eventual result was a community split that produced Bitcoin Cash in 2017, while Bitcoin itself pursued the SegWit and Lightning Network path that Todd and Back advocated for in Hong Kong. At $389 per BTC, the cryptocurrency was still deeply undervalued relative to its future potential, and the decisions made at this workshop would help determine whether it could fulfill that promise.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. Cryptocurrency investments carry significant risk. Always conduct your own research before making investment decisions.