Yes but I think you guys are missing the point I'm trying to make which is how do you get onto the correct blockchain and make sure you are starting from the right starting point in a decentralized way?
I don't believe that is possible. Updated the first post to try to make it more clear what I'm trying to say.
Define
Correct Blockchain
If by Correct ,
you mean the one that the Majority supports, it is as easy as comparing your last block with 1 or 2 block explorers.
And that goes for PoW or PoS, especially if you are syncing your client for the 1st time.
The fact is since you receive blocks from multiple 3rd parties in PoW & PoS,
other clients, and if they are running a Sybil attack on you,
your client won't know the difference
(unless their is a checkpoint in the source code), or unless you verify thru another party. ie:blockexplorer
Yes, if you know the block you are building off of, then yes, you can verify you are building off of the same block. But what if you are downloading the blockchain for the 1st time, how do you know which block is the correct 1st block in a purely decentralized and algorithmic way that is hard to 51% attack?
No matter which algorithm, in order to determine which blockchain is the correct blockchain, Proof of Stake blockchain users need to trust that they have been told the correct initial account balances. How can you prove in a decentralized manner whether you are mining the correct blockchain? You can't without outside help. This makes Proof of Stake practically useless.
And along the same lines, POW-POS hybrids are only as strong/decentralized as their Proof of Work component.
Agreed?
Your confusion is this, PoW also receives block info from 3rd party clients, if I isolate your system from the others, I can make it see anything I want , as long as it meets the specs in the source code.
PoW or PoS can only determine the chain that matches it specs, as long as that requirement is met, anything else can be manipulated depending on your ability to isolate that node, and only by verifying thru a 3rd party can you be certain you are on the majority supported chain.
Put Simply , there is no correct chain in PoW or PoS, there is only the Majority Supported Chain.
People seem to forget in 2013 , the miners overwrote Bitcoin chain and basically used the collusion of the majority to determine a new majority chain.
https://bitcoinmagazine.com/articles/bitcoin-network-shaken-by-blockchain-fork-1363144448/The difference is with Proof of Work, you can verify that a large amount of work went into creating the block. Until you choose which initial block to trust in a centralized manner, you cannot verify this in a Proof of Stake system.