Ethereum enthusiasts 2021-06-19 03:20:38 阅读数:871
The original title | Beyond electricity ——PoS Not the Savior
author : KF
translate : jianqi
Cryptography inside and outside the monetary circle , More and more people put their hopes on proof of rights and interests （Proof-of-stake,PoS） It can not only contribute the advantages of cryptography currency to us 、 It can also avoid workload proof （Proof-ofwork,PoW） Energy consumption property of . This wish will come to nothing , because Paul Sztorc stay 2015 The year is just around the corner. “nothing is cheaper than proof of work” This is discussed in the article （ Chinese version ）.PoS It's just confusing costs , But it's impossible to eliminate them . Here it is , I want to talk about why PoW It's like democracy ： It's the worst way , But it's the only one that works . This paper does not discuss whether the security of cryptocurrency is “ Worth ” At such a high price , Just focus on PoS Is it an efficient way .
To make a reasonable comparison PoW and PoS We need to put the cost （ Carbon footprint ） And benefits （ Blockchain security ） Take into account . therefore , Our problem can be either “ To get a given security , Is the environmental cost of proof of equity lower ”, It can also be “ Given the cost , Can proof of interest be more secure ”？ The two problems are logically equivalent . In this paper , We'll take the second way ：
axiom #1： The most environmentally friendly cryptography currency , It should be the most efficient one when buying security .
Money is not magic . If money wants to circulate, it must have certain security , And the way to get security is more efficient ; And the most efficient technology , There will also be the smallest environmental carbon footprint . It's a very useful point of view , Because it reminds us of a profound economic law ： Marginal revenue equals marginal cost . A blockchain , It cost X In terms of safety , That means miners will spend a total of X Yuan to compete for this award .
axiom #2： If a cryptographic currency buys value X The security of yuan , Its verifier （ To get a reward ） There will be value X The cost of yuan .
This is an unbreakable economic law of competition . Any miner who spends less than he gets , Will be defeated by miners who are willing to spend more ; And any miner who spends more than he gets , It's going to go bankrupt in the end . A blockchain costs X In terms of safety , Eventually, it's going to cost the miners X Yuan to defend this blockchain . The proportion of different types of spending may change , But all the expenses add up to X element . The difference is the same as a jin of cotton and a jin of iron .
People say “ Bitcoin wastes energy ” When , What they mean is that electricity is needed to drive the mining equipment that produces bitcoin blocks ; Ironically , One side , This part of energy is obviously not the whole energy used by bitcoin network , And just a part of it ; On the other hand , This part is the most direct part to protect the blockchain , So it is least Wasteful . To fully measure the carbon footprint of bitcoin , We also have to consider the cost of hardware （ Manufacturing and scrap costs ） And the cost of normal business operations （ To decorate a decent office , And fly to bitcoin conferences ）. The latter two types of costs are more ambiguous , More difficult to estimate . But to understand the impact of the whole system , They are just as important .
axiom #3： Consider the carbon footprint of a system , You have to consider all aspects of the verifier's expenses .
These three kinds of activities , There's a waste in every one of them . Bitcoin networks inevitably have isolated blocks , That's a waste of energy to dig out this solitary block . Some of the hardware is made , But operational efficiency is not perfect . Some operational overhead is necessary , Some just change places to drink tea . A kind of expenditure is closely related to the actual work of verifying the blockchain , The more efficient it is in exchange for blockchain security . It's similar to machines that are more efficient with fewer degrees of freedom ： One more part will make more useless work . The same goes for the economic system —— The more structures , The less efficient .
for instance ： Travel for a good relationship with a big client , It can be abstracted to improve the efficiency of the whole business , So it's also helpful to buy Security —— But it's very indirect , And the effect of buying security may not be as good as the same spending on electricity . The more a cryptography currency spends its security budget directly on electricity , The more secure it is ; The more money you spend on commercial operators , The less secure it is . Mining enterprises CEO It may be necessary for the company itself , But they don't contribute much to network security .
axiom #4： The more the expenditure is related to the actual actions of verifying the blockchain , The more efficient its purchase security is .
therefore , Sometimes you see people talking about ASIC 1 , Think they corrupt the environmental impact of a cryptographic currency , But it's actually the opposite . Specialization of mining equipment , So that the unit hardware can produce more computing power , This means that the security budget of blockchain is less spent on hardware , More on electricity . It's good for efficiency —— ASIC Mining is fundamentally better than traditional CPU Mining should be cleaner , because ASIC It's more efficient at turning energy into safety （ It's cheaper ）.
That's why people misunderstand “ Space proof （Proof-of-space）” The cryptography of classes （ such as Chia）（ They use memory instead of computing power to validate blockchains ） Impact on the environment . Using hard disks as a scarce resource to generate security doesn't reduce costs , It's just getting the security budget of the blockchain out of the electricity 、 It's hardware . If you only look at electricity consumption to measure the carbon emissions of cryptocurrency , You feel like we've made great progress —— But if you take into account the cost of hardware , You'll find it's a big loss of efficiency .
There are many idle hard disks in the world at present , therefore Chia It's like getting some subsidies . But don't expect it to last forever . Wait until some cryptography currency succeeds in monetizing computer memory ,GPU What has happened on the Internet will be repeated in the related hardware field . what's more , In the end, the system will be bigger than the same size, but based on PoW My system is worse , Because the security budget is spent on developing hardware , And that's less efficient than the security budget that's directly spent on electricity .
“ Tom's Hardware It has been reported that Chia Soaring prices and the shortage of large capacity mechanical hard disks . But what's more serious may be solid state drives （ The shortage of ）, Because you also need a solid state drive to make something that can fill a large drive Bram Cohen BinggoTM card ”
Conclusion #1： The most environmentally friendly cryptography currency , It's about spending the safety budget on the issues that are most closely related to the verification work .
Chia And other blockchains that use spatial proofs , It's still easier to follow PoW Compared with , Because it's easy to imagine old hard drives filling landfills , So it's easy to be sure , they “ Really? ” Impact on the environment . however , Lost capital also has a real impact on the environment . Because the money can be spent on carbon capture technology and carbon efficiency research , And so on . people “ Feeling ” They're free （ There is no consumption of ）, Just because humans are not good at thinking about the value of time （time-value）. If capital is really free , The miner won't have to pay any price .
Sometimes you'll see people claiming that proof of rights and interests can be wasted from an individual point of view , But from a social point of view, it's a saving , It's like Dan Robinson Yes ：
“ Suppose your religion requires you to prove your sincerity with your own sacrifice . You can throw a cow into the crater , You can also give it to strangers . Both things are equally expensive for you （ So they all meet the commandments ）, But the social cost of the first is higher .”
The opposite is true . Locking in capital is not a waste for you personally , because PoS The pledge algorithm will compensate you —— This capital has not been thrown into the volcano , It makes money for you , With other ETH At the expense of the holder . Locking in capital is not the same as giving it to strangers , Because there's no stranger taking over the money . The verifier did not “ Distribute their capital equally to everyone ”, actually , It's that everyone pays equally for the verifier's work （ The form is new ETH）. and , Thank you #2, We know that the verifier gets paid Exactly equal to The cost of these funds .
On the other hand , Lock in capital from a social point of view Namely It's a waste , Because that capital can no longer be used to build factories 、 Funding research and doing everything that's good for society . Think 2008 The financial crisis of —— No factories were destroyed , No house has collapsed , There is no loss of any physical assets . The consequence is just a loss of capital —— But it's still a very, very heavy social cost . Capital is a special form of information accumulation , What is condensed is the information about the optimal allocation of resources . The loss of information is not the same as the loss of something tangible , But it's also a loss , Even worse .
therefore , Remember the axioms #1 And axioms #2,PoS and PoW The fair comparison should be like this ：
There is no proof of interest （ It's impossible ） Eliminate the cost of miners , Just put PoW Part of system spending on electricity is turned into capital spending . Lock in the externality of capital , Compared to the externality of electricity consumption , It's a complex and delicate issue —— But the bad thing is ,PoS Proponents of the system tend to pretend that electricity is （ System operation ） The only price to pay ：
- This is a misleading comparison , From Ethereum foundation blog .-
disappointing . The Ethereum foundation knows ,“ The average single transaction consumes energy ” It's a totally meaningless indicator , Using this data in this way is deliberate deception . The point is not at all PoS Whether the system uses less energy —— It's really less , But that's not all . A meaningful discussion is ： It's better to consume capital , It's better to consume electricity ？ Any support PoS Instead of discussing the theory of cost of capital , It's all fundamentally wrong .
stay PoW/PoS In this debate ,PoS Supporters can often take advantage of ： There has never been a fully decentralized proof of interest system . It also means that ,PoS Supporters can fantasize about how efficient the final solution can be 、 How elegant . The known mining algorithms are not perfect and efficient （ For example, being “ Selfish mining ” problem ）, and , There is also no reason to believe that PoS The system can be impeccable —— however , Before the solution finally takes shape ,PoS Proponents don't have to think about what the verifier might use to cheat the system Specifically Strategy .
The more opportunities to juggle the system , The looser the relationship between security budget and actual verification . because “ No one has ever tried real proof of interest ”, First of all, we don't know how much security budget can be converted into locked in capital , What's more, I don't know how efficient lock in capital is in generating security . According to the definition ,PoW It's tightly coupled with verification , but PoS, As of writing until , Not yet fully defined .
Observe #1：PoW Tightly coupled with security . But it's not clear PoS To what extent .
Suppose we all agree , From the perspective of security and efficiency , The efficiency of locking in capital and mining is the same , Then there's only one problem left , Namely “ Externality ”. This is also where I think rational discussionists can still disagree on the trade-offs .
In the short term ,PoW The system has to compete with other projects to use energy , But in the long run , It will stimulate the development and production of cheap energy , And that will gradually reduce the cost of electricity , Good for all （ Whether it's financial use or environmental protection ）. Cheap electricity will also lead to new technologies and more production .
Proof of equity will compete with other projects to use capital in the short term , But it doesn't inspire the creation of more capital , So it will gradually increase the cost of capital . The cost of capital is higher , It means fewer projects —— Fewer factories , And less research .
You prefer PoW The externality of this is still PoS The externality of , It may depend on what you think is the solution to the environmental crisis by investing in Technological Development 、 It's better to save current consumption 2. To save the earth , We should make cheaper renewable energy , Or should we make everything more expensive ？
Observe #2： The workload proved to encourage future investment . And proof of rights and interests is to curb exploration .
As we said earlier , We don't know whether a fully decentralized proof of rights system can be realized . The existing one flaunts itself as PoS The cryptography of the system , Basically, it depends on some kind of centralized coordinator or “ checkpoint （checkpoint）”. From Ethereum from 2015 Since its inception in , They've been trying to transform into a completely decentralized PoS System , And now , They just launched Phase 0, It just supports the verifier's pledge …… Once you lock the money in , I can't get out , It doesn't cost .
About PoS Is the system safe enough , There's a lot of debate （ see “ Long range attack ”、“nothing-at-stake”、“ The workload spans time / Equity is the opposite ”）. These are all open questions in research , Instead of the to-do list in the implementation process . We don't know how long it will take to come up with a good plan , It's doubtful whether there's even a good plan . Look at this. 2017 Posts from ：
PoS Maybe “ Can run ”, It's just that the way it works is morbid .PoW People who have access to cheap electricity , And reward them with capital . Though not entirely equal , But not in a positive feedback loop .PoS They prefer those who can get capital at a cheap price , And reward them with capital , This creates a cycle . The rich will become richer , And the more money you have , The easier it is to be rich .
If proof of interest “ You can start ”, But the end result is that all power is concentrated in the hands of a small number of super rich institutions , And they can control the system forever , Then it can't solve the problem that cryptography money wants to solve . Then we might as well continue to use the current central bank and those “ Insiders who benefit from the Cantillon effect ” Composed system . We hope that cryptocurrency can break this system , Not old wine in new bottles .
Observe #3： The workload proved to exist , And proved that it can continue to grow . But proof of interest is still an unsolved problem .
axiom #1： The most environmentally friendly cryptography currency , It should be the most efficient one when buying security .
Unfortunately , After a detailed investigation , We know PoS Most of “ advantage ” It's all just looking bright , And there are many major public challenges . At least so far , It's also a utopian fantasy , Not a realistic choice . and PoW Although there are shortcomings , To build a network that doesn't need to trust centralized authority , But it's still the best known solution （ actually , And the only solution ）.
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