So as long as you have no extended downtime, your nodes know what the right chain has to look like. Ethereum dynamically adds checkpoints so that block reorgs can't reach too far into the past but that is mostly a convenience function as it alone couldn't solve this issue.
Now, there is a problem if you are a new participant. Then you can't decide which chain is the right one. You could observe for a while and choose the one that has more validators but in theory, there's the possibility that there's a contentious hard fork going on.
In this case you need to get the information which chain is the right one from outside sources. E.g. like your preferred exchange or the official subreddit.
This is the most glaring difference between POS and POW. With POW, you don't need any outside information as you can just verify which chain needed more work to be created and this is by definition the correct one.
POW leverages physics to be completely self contained for the price of energy consumption.
And with algorithmic difficulty adjustment in PoW, you don't pick the chain with the headers with the most 0s preceding, you pick the longest chain. A longer chain with a sudden difficulty adjustment is an obvious invalid chain, but I digress
The bigger problems for me are the nothing st stake problem. Why pick one chain when you're new? Just pick both, it costs virtually nothing, and when you figure out which one is more profitable to you, just let the stake in the other one get slashed. Validators can help an attack on the network just in case it becomes profitable, and if it doesn't they lose nothing, because they incur no ongoing costs in the real world to do so.
But then, I wonder, if we're all anyway looking for the trustworthy data ourselves (based on general human intuition), why use blockchain at all? Why not just apply the same level of trust towards, say, a regular database?
My thinking is that PoS makes it easier to trust because we'd only have to trust the beginning of the chain, and the rest is verified via the PoS math. Whereas with a normal database we'd have no real way of verifying it hasn't been tampered with?
It does seem a bit scary though that so much money is going into a system where "you have to find the trustworthy data yourself based on your own social network".
You don't have the same level of transparency with a regular database. You can't look into the databases of Google or Facebook or of your bank and see what's going on. You have to trust them to some degree.
From a high level view, any blockchain solution is less efficient than a centralized one. If you don't care about trust and transparency, a centralized solution will always be better.
> It does seem a bit scary though that so much money is going into a system where "you have to find the trustworthy data yourself based on your own social network".
The whole cryptocurrency thing is about reducing trusting third parties. But that adds burden on your part. With Bitcoin's POW you have to do less work for getting to the trust level you are comfortable with because we are pretty certain that no human can change physics. With POS, you need to compensate for the loss of the physical part.
Does that sum assume that every coin will be staked? As I understand it, coins staked for validation are held in escrow and can’t be used for transactions until the validator node unstakes the coins. Surely only a small percentage of coins will be staked at any given time.
https://coinmarketcap.com/currencies/ethereum/
and most of it is not staked
If the former; as someone with little knowledge of cryptocurrency the post read fairly convincingly to me. In what ways is it misinformed?
Basically he built up a strawman and then burned it to the ground.
In my skimming, I can’t find anything that addresses this — and especially not anything that merits describing TFA as a strawman.
In reality, everyone just ignores the attacker's chain, because it attempts to rewrite not seconds, minutes, or days of canonical history (periods of time short enough that the identity of the canonical chain might be in question), but many months of history that the entire world has already agreed on and that node software refuses to reorganize the chain past.
This post by Vitalik in 2014, shortly before the launch of Ethereum, explains why this "weak subjectivity" property of PoS is not nearly as problematic as PoW proponents make it out to be.
https://blog.ethereum.org/2014/11/25/proof-stake-learned-lov...
If you’re still worried about that happening to some ETH you received, wait for the blocks to finalize. Once they have, they will never be reverted without a change to the protocol.