How is it possible or how is it challenging? The FAQ document describes both. It relies on a principle called "Weak Subjectivity" that Vitalik describes in deta

How is it possible or how is it challenging? The FAQ document describes both. It relies on a principle called "Weak Subjectivity" that Vitalik describes in detail here: https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity/ https://blog.ethereum.org/2014/11/25/proof-stake-learned-lov... I'll admit, that I don't have a complete understanding of the theory behind PoS systems, and there are certainly tradeoffs between PoW and PoS, but Vitalik makes the arguments that the benefits of lower energy consumption and quicker transaction fees outweigh the weakened guarantees. Whether you agree with him depends on your values with respect to Cryptocurrency.