[gonehome]

This is the best (and also approachable well-written) book on the topic that I've found: https://bitcoinbook.cs.princeton.edu/

My (possibly incorrect) understanding is that POW is computationally expensive because that large investment of computation is what creates a chain of successive blocks (the blockchain). This prevents someone from rewriting history of transactions on the public chain (which would allow them to 'double-spend' or to take their money back).

POW currencies are guaranteed to prevent this kind of abuse unless any individual entity is able to get more than 51%. There's an incentive in addition to this because corrupting the integrity of the network would also devalue the currency. Larger networks (like BTC) are harder to do a hostile take over of because it's harder to get that much compute (though mining centralization is a risk).

POS relies on some variant individuals 'staking' coins to enable transactions, this means putting them up in escrow sort of in the network (they are paid small fees for this based on how much they stake) and if abuse is attempted, the system takes those staked coins away. There are no mathematical guarantees outside of this incentive.

POS is not as standardized across different currencies so I may be missing important bits in my understanding.

[plokiju]

> POW currencies are guaranteed to prevent this kind of abuse unless any individual entity is able to get more than 51%. There's an incentive in addition to this because corrupting the integrity of the network would also devalue the currency. Larger networks (like BTC) are harder to do a hostile take over of because it's harder to get that much compute (though mining centralization is a risk).

Couldn't this be re-written as:

> POS currencies are guaranteed to prevent this kind of abuse unless any individual entity is able to get more than 51% of the staked currency. There's an incentive in addition to this because corrupting the integrity of the network would also devalue the currency. Larger networks (like ETH) are harder to do a hostile take over of because it's harder to get that much stake (though validator centralization is a risk).

My (non-expert) interpretation is that staking is just an abstraction of mining, and they are secured by the same incentive system

[gonehome]

This comment above does a better job than I did at explaining why the staking incentive is somewhat flawed: https://news.ycombinator.com/item?id=26810686

[plokiju]

> PoS is closed-membership with a veneer of open-membership, because the means of coin production are tied to owning a coin already. What this means in practice is that no rational coin-owner is going to sell you coins at a fast enough rate that you'll be able to increase your means of coin production

It seems to me like they're arguing that PoW is more egalitarian/decentralized, which may be a fair point. But using the same argument, attackers being forced to buy stake in the open market should make PoS even more secure against 51% attacks than PoW.

I think this is a good post explaining the tradeoffs: https://vitalik.ca/general/2020/11/06/pos2020.html

[jude-]

Why would they need to buy 51% stake? Just buy x% and then knock the remaining staking nodes offline so that less than 2x% stake remains participating. That's often much cheaper.