https://youtu.be/UyxDaPGIXig

Problem

Pick 2 out of

• Decentralized

• Secure

• Fast

Bitcoin chooses

• Decentralized

• Secure

But loses 'fast'

Bitcoin's proof of work limits it's throughput to 3-7 transactions per second

This is already showing as too little.

A lot of energy is wasted in bitcoin

Proposed solutions

• [bitcoin cash] Increase blocksize

• Proof of stake (instead of proof of work)

• [eos] Delegated proof of stake (DPOS sacrifices decentralisation)

• [ripple] transfer 'I owe you' (centralized)

• [stellar] stellar consensus protocol

• Side-chains (secondary layer for lower cost and higher speed)

• Off-chains (move entire computation outside blockchain)

• [lightning] Offchain state channels (part of the blockchain is locked by a smart contract that requires 100% consensus, then is transfered back to the blockchain and the state channel is closed)

• Offchain computations

• [plasma] only block headers in main chain

• Etherium sharding

• Decentralized storage