Who is Mike Hearn?

Hello again. It’s been a while.

People have been emailing me about once a week or so for the last year to ask if I’m coming back to Bitcoin now that Bitcoin Cash exists. And a couple of weeks ago I was summoned on a thread called “Ask Mike Hearn Anything”, but that was nothing to do with me and I was on holiday in Japan at the time. So I figured I should just answer all the different questions and answers in one place rather than keep doing it individually over email.

Firstly, thanks for the kind words on this sub. I don’t take part anymore but I still visit occasionally to see what people are talking about, and the people posting nice messages is a pleasant change from three years ago.

Secondly, who am I? Some new Bitcoiners might not know.

I am Satoshi.

Just kidding. I’m not Satoshi. I was a Bitcoin developer for about five years, from 2010-2015. I was also one of the first Bitcoin users, sending my first coins in April 2009 (to SN), about 4 months after the genesis block. I worked on various things:

• I wrote the first documentation on smart contracts, gave the first talk on the concept and based on some hints from Satoshi designed and documented what I called “micropayment channels“.

• I had numerous email exchanges with Satoshi. I didn’t know at the time that this was very rare.

• My main effort was an implementation of a Java library called bitcoinj. This was the engine used in the first p2p mobile wallet (“Bitcoin Wallet for Android”), and the first p2p desktop wallet that was faster to run than Bitcoin [Core] itself (MultiBit). These together were responsible for around 2.5 million user installs at a time when downloading the full block chain was becoming too slow for normal users to tolerate and the only alternative was a “bitbank” or cloud-hosted wallet. It was used in the first trustless gambling site (SatoshiDice), over 100 products and projects, and many academic research papers.

• With Gavin Andresen and others I designed some upgrades to the Bitcoin protocol like Bloom filtering and BIP70.

• With Matt Corrallo I implemented and demonstrated the first version of (micro)payment channels. I put together a demo of a file server that charged micropayments using a GUI called Payfile (mentioned in New Scientist here). I used to have a video of this but unfortunately it no longer seems to be on YouTube. Payment channels went on to be used in the design of the Lightning Network.

• I built an open source peer to peer Kickstarter-style crowdfunding app that used smart contracts, called Lighthouse. It is no longer maintained or available but there’s still an intro video here, the source code is here, and I gave a development retrospective talk on what was easy and what was hard about building really decentralised apps on Bitcoin. It was intended to be used to fund Bitcoin upgrades.

• I spoke at a lot of conferences, like this talk on autonomous agents that use cryptocurrency. My last conference appearance was a 30 minute session where I live coded a block chain timestamping app from scratch.

You can see a trend here – I was always interested in developing peer to peer decentralised applications that used Bitcoin.

But what I’m best known for is my role in the block size debate/civil war, documented by Nathaniel Popper in the New York Times. I spent most of 2015 writing extensively about why various proposals from the small-block/Blockstream faction weren’t going to work (e.g. on replace by fee, lightning network, what would occur if no hard fork happened, soft forks, scaling conferences etc). After Blockstream successfully took over Bitcoin Core and expelled anyone who opposed them, Gavin and I forked Bitcoin Core to create Bitcoin XT, the first alternative node implementation to gain any serious usage. The creation of XT led to the imposition of censorship across all Bitcoin discussion forums and news outlets, resulted in the creation of this sub, and Core supporters paid a botnet operator to force XT nodes offline with DDoS attacks. They also convinced the miners and wider community to do nothing for years, resulting in the eventual overload of the main network.

I left the project at the start of 2016, documenting my reasons and what I expected to happen in my final essay on Bitcoin in which I said I considered it a failed experiment. Along with the article in the New York Times this pierced the censorship, made the wider world aware of what was going on, and thus my last gift to the community was a 20% drop in price (it soon recovered).