Looking back on 2018, it's difficult to remember a month or even a week in which blockchains weren't making news, making it difficult to separate the legitimate scientific breakthroughs from the hype of cryptocurrency speculation. To help us distinguish fact from fiction and start to form a picture of where the future of blockchain technology may lie, we're turning to Professor Maurice Herlihy of Brown CS, asking him one question per week and compiling his answers below.
Long known for his research with multiprocessor synchronization and application of combinatorial topology to distributed computing, much of Maurice's recent work has dealt with blockchains. He delivered the PODC 2017 keynote ("Blockchains and the Future of Distributed Computing"), recently won a grant from the Ethereum Foundation for research into the creation of transactions that span multiple blockchains, and hit maximum attendance in his new course on blockchains and cryptocurrencies, one of very few courses nationwide that deals with the subject from a scientific perspective.
1) What led you to create a course about blockchains and cryptocurrencies, and why do you think there's been so much interest in it?
I wanted to teach this course because the study of systems that manage trust is an important emerging direction in distributed computing, and right now blockchains and cryptocurrencies are the most prominent examples.
The level of excitement and hype surrounding blockchain is a mixed blessing: on the one hand it attracts the brightest students and developers, but on the other hand the field's credibility suffers every time some coin's price takes a predictable nosedive. One of the messages I want to convey to students is that the scientific value of studying blockchain-related algorithms, data structures, and systems is independent of the fortunes of any particular coin, company, or crackpot economic belief.
2) What makes your course different from others on the same subject?
My course differs from most of the blockchain courses I've seen (and there are not that many) in the following ways. First, I plan to focus less on the details of Bitcoin's plumbing, and more on later technical innovations such as smart contracts and privacy coins, along with a dose of cold scrutiny about overheated claims to decentralization, censorship-resistance, and similar properties. Second, I want to look at blockchain applications other than currencies. Finally, I think private (permissioned) blockchains, although anathema to some blockchain culture warriors, are going to have a quiet but long-lasting influence on society, and I want to make sure their strengths and weaknesses are thoroughly understood.
3) Can you tell us more about atomic cross-chain transactions and why they're important?
Atomic cross-chain transactions will be essential if blockchain technology is to live up to its promise. In the future, there will be many blockchains. Different institutions will require different blockchains to manage different resources, and even within a single institution it may make sense to split a blockchain into multiple shards (distinct co-operating chains) for scalability. If blockchain technology will be useful only if it will be possible to conduct multi-step atomic transactions that span multiple blockchains.