A note on the medium:

Opera used to support @media projection, which was good for making slide shows.

Nobody supports that any more, including Opera, which is lame.

So I hacked together some javascript to simulate slideshow mode.

Controls: previous, next, beginning, end.

Hit n to see the first slide.

Are you tired of sitting? Get up!

Blockchain stuff that's not Bitcoin

Dan Talking About How Great Hashes Are Again

What makes a blockchain a blockchain?

What makes a blockchain a blockchain?

What makes a blockchain a blockchain?

What makes a blockchain useful?

Currencies are a popular use because

Making $$$ incentivizes doing the work to generate new blocks, and the work required gives the currency value.

Currencies are a popular use because

"We mine bitcoins because it is hard to mine bitcoins"

i.e. they're basically a huge waste of electricity so that someone (not you) can get rich.

Some Different Blockchains


Transactions can create and buy 'gas' to run 'smart contracts'


pragma solidity ^0.4.0;

contract Coin {
	// The keyword "public" makes those variables
	// readable from outside.
	address public minter;
	mapping (address => uint) public balances;
	// Events allow light clients to react on
	// changes efficiently.
	event Sent(address from, address to, uint amount);
	// This is the constructor whose code is
	// run only when the contract is created.
	function Coin() {
		minter = msg.sender;
	function mint(address receiver, uint amount) {
	if (msg.sender != minter) return;
		balances[receiver] += amount;
	function send(address receiver, uint amount) {
		if (balances[msg.sender] < amount) return;
		balances[msg.sender] -= amount;
		balances[receiver] += amount;
		Sent(msg.sender, receiver, amount);



Blockchain EHR


Blockchain EHR

Solution: Link your records (encrypted) in a blockchain!

Experimental implementation: MedRec

To Tha Moon!

This approach may be useful for a lot more than just health records!

Watch for a blockchain-based distributed social network.

In Conclusion