timestamp 1:20:50 - 1:39:32

We learned about how the hashes are derived.

We also talked about the differences between PoW (proof of work) and PoS (proof of stake), and why we're moving a way from PoW because PoS is much cheaper computationally.

We also learned about Sybil and 51% attacks. Sybil attacks are peer-to-peer attacks, and blockchains are resistent.

Patrick was also nice enough to clarify that the problem is not always to make all of the first four number a zero. Blockchains can choose easier or more complex problems in order to regulate the "block time", or how long it takes for the blockchain to be published.

Ethereum uses the Nakamoto consensus, which uses a combination of the "longest chain rule" and proof of work to determine which blockchain takes point.