2/ PoW was originally invented as a measure against email spams (https://en.m.wikipedia.org/wiki/Proof-of-work_system …). Only later it was adapted to be used in digital cash, starting with @adam3us 's hashcash.
-
-
Show this thread
-
3/ What PoW mining actually does under the hood, is that it converts kinetic energy (electricity) into a ledger block.
Show this thread -
4/ A mining machine repeatedly performs hash operations until it solves a cryptographic puzzle. All hash operations are thrown away except for the one hash that solves it.
Show this thread -
5/ This one tiny hash, which itself takes very little energy to compute, is a direct representation of the huge ball of energy that was required to produce it. The “proof” that the block was minted.
Show this thread -
6/ In order to rewrite the block, an attacker later will have to spend a roughly equivalent number of hash operations that was originally required.
Show this thread -
7/ Let’s say that again: reverting takes an equivalent amount of hash operations, not an equivalent amount of energy. That is because the hash is only a *representation of the energy used*, not the energy itself.
Show this thread -
8/ Over time, this representation of energy becomes less & less accurate - as improved hardware becomes more efficient. Energy itself doesn’t change, but its old representations “leak”.
Show this thread -
9/ Another way to visualize this process, is to think of PoW mining as attaching physical weights to virtual blocks. Over time the older blocks get damaged and get lighter & lighter. This also reduces the total weight of the chain, everything else being equal.
Show this thread -
10/ Bitcoin combats this attrition process by constantly creating new blocks with fresh weights. This ensures that the tip of the chain is always heavy in the present, protecting the integrity of the entire chain. Heavy chain == secure chain.
Show this thread -
11/ (Some have suggested that “heaviest chain” is a better terminology than Satoshi’s “longest chain.” Longest chain can be very misleading when we don’t really mean length in the literal sense.)
Show this thread -
12/ SHA256 is the hash function that backs Bitcoin PoW mining. SHA256 protects the ledger from being rewritten. One hash in (to mine), one hash out (to revert). This is what gives Bitcoin its immutability property.
Show this thread -
13/ It’s amazing when you think about it. Hash operations dedicate their entire existence to the purpose of securing the ledger! Rarely anything in the real world has 100% dedication & efficiency. (e.g.: contrast that with gasoline & the combustion engine).
Show this thread -
14/ In reality, it is probably not 100% but something close to it. Because irreversibility relies on the hashed results being uniformly random (just like when you roll a dice), and algorithms can’t truly simulate real-world randomness.
Show this thread -
15/ Luckily for us, hash functions such as SHA256 have shown to be sufficiently random, aka “pseudorandom”. SHA256 has been reviewed & stress-tested for years, and has a rich research literature behind it. So it's not something we have to be too concerned about (yet).
Show this thread -
16/ Fundamentally, I believe the idea of “attaching energy” to blocks is the right one & probably the only way to simulate immutability virtually.
Show this thread -
17/ Using energy burnt to back a block allows us to view immutability objectively. Whereas any non-energy-based method ultimately requires someone’s subjective interpretation of immutability.https://twitter.com/hugohanoi/status/953346280134029312 …
Show this thread -
18/ By attaching energy to a block, we give it “form”, allowing it to have real weight & consequences in the physical world. We can also think of PoW as the link that brings a bunch of 0s & 1s into life.
Show this thread -
19/ In other words, PoW is the bridge between the digital & the physical.
Show this thread -
20/ Compare that to some cryptokitties that someone creates, modifies & removes as they see fit. Their uniqueness & existence are neither guaranteed nor reliable.
Show this thread -
21/ Even if the current variant of PoW fails, I’m confident that there will be other ways of attaching energy to a block.
Show this thread -
22/ In conclusion, PoW’s application in blockchains might prove to be far more significant & wide reaching than what it was originally invented for.
Show this thread -
23/ PoW gives us immutability, which gives us uncensorable money, which could potentially change how society organizes itself ( read
@NickSzabo4 ‘s wonderful essay on social scalability for more on that: http://unenumerated.blogspot.com/2017/02/money-blockchains-and-social-scalability.html … ).Show this thread
End of conversation
New conversation -
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.
