That's not what happened with the Bitcoin Cash fork though -- it resulted in "sloshing" between the two networks as miners would congregate in the currently-most-profitable network. That makes it so at any given time, one of the networks is easy to attack.
Look at the block creation and hash rates for BTC vs BCH:
Adding layers of complexity like Ethereum's Casper to solve the incentive incompatibilities caused by the nothing at stake and long range attacks do not address the fundamental issues, as consensus then require users to agree on a list of bonded validators (for which there is no switching cost). "Phone a friend" consensus is objectively weaker as a security model compared to POW which just requires users to validate the rules and calculate the chain with the most work.
POW is secure because it requires energy from outside the system to be provably burned. It's thermodynamically sound in that respect. /u/nullc recently described POS as a logical tautalogy which I think captures the issue well. If chains were a car, Bitcoin would be fueled by gas and a POS coin would be fueled by the leather on the seats. You're not going to get very far.
Due to the algorithms being inefficient
If that is resolved then the entire history will be suspect
And any thermodynamically similar future will have to compete on constants and exponents
Or you could regulate the hardware, 'this blockchain is only compatible with, and so calculated on, a gateway lt1700 with exactly 640k of ram' ;P
> Due to the algorithms being inefficient
This is by design, when the hardware gets better Bitcoin network starts requiring even more work, so being "efficient" is actually what is not desired here. See: https://en.bitcoin.it/wiki/Difficulty
>the miners must select one chain to mine
I am pointing out that the "sloshing" is in fact perfect evidence that they are only mining one chain at a time, or splitting their hashpower to varying proportions. This is completely normal and healthy miner behavior, they are simply greedy actors looking for the most profit. They cannot however mine both chains with their full hashpower for free (as you can with PoS), and this is an essential understanding when analyzing the security model of a consensus algorithm.
Also, the oscillations are most commonly exploitable only when the difficulty adjustments happen very quickly (see: BCH's EDA), so if 70% of the hashpower left, even if 16% of the remaining hashpower was malicious, the efficacy of a 51% will be handicapped by the disproportionately high difficulty.
I don’t care whether sloshing is “normal healthy behavior”. I care whether a fork has become easy to attack. You seem to focus on every topic but that one.
Original comment: "Also, with Proof of [Work] you get protection against an explosion of too many hard forks..."
My reply: "That's not what happened with the Bitcoin Cash fork though ... any given time, one of the networks is easy[er than 51%] to attack."
If you're not disputing that point, then you're not refuting my objection to that original comment.
It is not true that on PoS you can mine multiple forked chains without being penalized. On the chain that "wins" you can be penalized for mining multiple chains which is clearly bad behavior.
The main problems of PoS that Casper, the Ethereum implementation, is trying to solve are "Nothing at Stake" and "Long Range Attacks". Both problems are being tackled right now and close to be solved.
Make a technical or economic argument.
Meanwhile: http://www.truthcoin.info/blog/pow-cheapest/
You're confusing multiple branches competing for being the most-cumulative-difficulty branch, with multiple distinct cryptocurrencies resulting from a hardforking code change.
Penalization only applies to the first case, but the parent was talking about the latter case. E.g. a miner could mine both ETH and ETC once both adopt PoS.
I don't see any problem in hard forks and being able to stake on multiple chains. Let people hard fork as much as they want and decide, later on, which chains hold value.
How? Who decides?
This is really where every PoS algorithm seems to break down. The whole idea of blockchain is to build a decentralized consensus, and PoS just handwaves it away.
Every user of the system.
>How?
Mostly by taking in consideration the differences of the software from both chains.
I do. I prefer to call it "Proof of Burn" instead of "Proof of Work". With Proof of Burn you can assure that it's difficult to create fake blocks because the attacker must burn even more petrol barrels that the good people.
Also, with Proof of Burn you get protection against an explosion of too many hard forks. If you have a hard fork in a Proof of Burn coin, the miners must select one chain to mine (or split the resources), so usually only one chain survives. In a Proof of Stake coin, after a hard fork the miners can continue mining in both chains.