BITCOIN FANS like to point out that, like gold, the cryptocurrency is in limited supply. Its protocol specifies that only 21m bitcoin will ever be mined, with the last batch due in the middle of the 22nd century. A fixed supply, say bitcoiners, ensures that, unlike ordinary currencies, it will not be eroded by inflation.
比特币爱好者喜欢讲，与黄金一样，加密货币的供应是有限的。比特币的协议规定，最多只能开采2100万个比特币，而最后一批比特币将在22世纪中期开采完。比特币人士认为，与普通货币不同的是，固定的供应能确保它不会受到通货膨胀的侵蚀。
But whereas the supply of bitcoin may be limited, that of cryptocurrencies is not. Bitcoin’s protocol is open-source, so there is nothing to stop others copying the idea. And they have done, with gusto. So far thousands of different cryptocurrencies have been launched. Like bitcoin, they have proved attractive to speculators. For example, XRP, issued by Ripple, a payments firm, rose from less than one cent to touch $3.46 in January this year (it has since dropped back to around $0.35). The magnitudes vary, but the price movements of cryptocurrencies tend to be correlated. When bitcoin is rising, the so-called “altcoins” tend to rise as well, and vice versa.
不过，即便比特币的供应有可能是有限的，加密货币的供应却并不非如此。比特币协议是开源的，因此无法阻止其他人照抄这个想法。他们已然这么做了，而且是兴致盎然。到目前为止，有数千种不同的加密货币面市。与比特币一样，这些加密货币对投机者颇有吸引力。例如，支付机构瑞波（Ripple）发行的瑞波币（XRP），从今年1月不到1美分的价格上涨至将近3.46美元（此后又下跌至0.35美元左右）。虽然加密货币涨跌的幅度各不一样，它们价格的变动趋势往往是连动。当比特币上涨时，这些的“山寨币”也会上涨，反之亦然。
Some of these altcoins are shady. Several projects have actually been called PonziCoin, and one, in 2014, seems to have done exactly what it promised, advertising a 120% annual return before folding soon after enough suckers had bought in. Some are meant as jokes: Dogecoin is based on an internet meme involving a Shibu Ina dog that went viral in 2013. Even so, in 2017 its price surged along with that of all the other cryptocurrencies, from $0.0002 to $0.017, an 85-fold increase. Dogecoins currently in circulation are worth a nominal $267m.
一些山寨币则游走在灰色地带。有好几个项目实际上被称为“庞式币”（PonziCoin），而有一个项目在2014年似乎实现了承诺，在吸引足够多的买家进入之后，很快就在封盘前打广告，称有高达120％的年回报率。有些项目则是笑话：Dogecoin源于个互联网动图，是在2013年互联网上风靡一时的石布狗。即便如此，Dogecoin在2017年的价格也随着其他加密货币的价格飙升，从0.0002美元上涨到0.017美元，增长了85倍。目前流通的Dogecoin的名义价值2.67亿美元。
Some altcoins, though, are sincere attempts to fix some of bitcoin’s perceived problems. One of these is that bitcoin is not truly anonymous. If a pile of it can be tied to a user’s real identity, the blockchain will reveal every transaction in which he received those coins. (This was a big help to the FBI agents who in 2013 arrested Ross Ulbricht, the founder of the Silk Road, an early online black market that did much of its business in bitcoin.)
然而，一些山寨币正努力尝试修复一些对比特币的认知问题。其中之一就是比特币不是真正的匿名。如果一堆比特币能与用户的真实身份绑定，区块链就会显示他每次接收比特币的交易。（这帮了邦调查局特工一大忙，他们在2013年逮捕了丝绸之路网站的创始人罗斯·乌布利希特（Ross Ulbricht）。该网站此前是一个网络黑市，有很多交易通过比特币进行。）
Zcash, Dash and Monero are all cryptocurrencies that aim to give users more privacy. Monero, in particular, quickly became a popular alternative to bitcoin in some of the less salubrious corners of the internet. “Stablecoins” such as Basis, Carbon and Tether, meanwhile, attempt to tame the volatility that makes cryptocurrencies attractive to speculators. Tether claims that each of its coins is backed by a US dollar. About 2.5bn Tether coins are currently in circulation. In 2017 the firm promised to hire external auditors to prove that it does, in fact, have a pile of real cash backing those coins. In March this year, still without an audit, it announced that it had parted ways with the firm it had hired.
Zcash、Dash和Monero是三种旨在更为用户保密。尤其是Monero在互联网的灰色角落里，迅速成为比特币的替代品，很受欢迎。同时，诸如Basis，Carbon和Tether等“稳定币”试图遏制加密货币吸引投机者的波动性。Tether表示它的币与美元挂钩。目前它约有25亿个币流通。2017年，该公司承诺聘请外部审计机构来证实它确实有真实现金支持这些币。可是，今年3月仍然没有进行审计，该声称与其聘用的审计机构在审计方法上没有达成一致。
In December 2017 the government of Venezuela, a country in deep economic trouble, announced that it had created the petro, a cryptocurrency supposedly backed by the country’s large oil reserves. It was designed in part to circumvent American sanctions. Nicolas Maduro, the country’s president, claimed that presales of the petro had raised $735m in precious foreign currency on the day it launched.
2017年12月，陷入严重经济困境的委内瑞拉政府宣布创建石油币——一种据称由该国庞大的石油储备所支持的加密货币。它的出现一部分原因是为了绕开美国的制裁。委内瑞拉总统尼古拉斯·马杜罗（Nicolas Maduro）声称，在石油币面市当天，以稀缺的美元计算，预售额就达到了7.35亿美元。
Many cryptocurrencies, though, go nowhere. Deadcoins.com, a site that keeps track of moribund ones, lists about 900 coins that have been abandoned by their creators or their users.
然而，许多加密货币根本就不流通。跟踪垂死加密货币网站Deadcoins.com列出了大约900个被创造者或用户抛弃的加密货币。
The best-known and most interesting twist on bitcoin’s original idea is Ethereum. The brainchild of a bitcoin enthusiast, Vitalik Buterin, it was launched in 2015. Its main innovation is to allow computer code—dubbed “smart contracts”—to reside on its blockchain. That code will be run in predefined circumstances, against a small payment in ether—the Ethereum network’s native cryptocurrency—to compensate the owner of whichever computer ends up running the program. These programs can interact with each other, which makes it possible to construct complex distributed blockchain-powered “dapps” (distributed apps).
在比特币的最初构想中，最出名，也最有趣的转折是以太坊。 比特币爱好者Vitalik Buterin在2015年提出这个创意。它的主要创新是允许计算机代码 ——名为“智能合约”——驻留在其区块链上。该代码运行在预先定义的环境之中，并以以太坊的原生加密货币“以太”作为小额支付，用补偿运行该程序电脑的拥有者。这些程序可以相互交互，使得构建复杂分布式区块链“dapps”（分布式应用程序）成为可能。
Into the ether
进入以太
That, in theory, makes Ethereum a more generalised system than bitcoin. The bitcoin blockchain is designed to do just one job: to serve as a ledger for electronic cash. An Ethereum dapp could be written to do the same thing, but other uses are possible, too. Golem, for instance, an Ethereum-powered project launched this year, is designed to create a “decentralised supercomputer”, offering users rewards for putting their computers’ spare capacity to work for other people. That has led to excited talk of Ethereum itself becoming a sort of “world computer you can’t shut down”, or even “Web 3.0”, on top of which could be built decentralised, user-controlled versions of everything from Facebook to Skype.
从理论上讲，这种方式使得以太坊能比比特币成为一个更大众化的系统。比特币区块链旨在完成一项工作：成为电子现金的分类账。可以编写一个以太坊“dapps”来做同样的事情，也可以有其他用途。例如，Golem是今年推出的由以太坊支持的项目，用来创建一个“去中心化的超级计算机”，用于奖励用记让他们的计算机的闲置算力为其他人工作。这致使人们兴奋地讨论以太坊，认为以太坊本身成为了一种“无法关闭的世界计算机”，甚至是“互联网 3.0”，其中最重要的是可以构建去中心化的的，由用户控制的Facebook和Skype。
For a world worried about the power of big internet firms, that could be an attractive prospect. Ethereum’s smart contracts started on a modest scale, involving things like automated casinos and lotteries. Then they became grander: the Decentralised Autonomous Organisation (DAO), for instance, founded in 2016, was designed as an automated investment fund.
对于一个担忧互联网巨头的权力的世界来说，这可能会是一个极具吸引力的前景。以太坊的智能合约最开始的规模不大，涉及自动化赌场和彩票等领域，之后就变得更加壮大了：如成立于2016年的分散自治组织（DAO）就规划为自动化投资基金。
It ended up as a cautionary tale about the difficulty of writing bug-free code. Its smart contract took money from contributors and allocated it to projects that its 11,000 members had voted on. But after $150m of ether was invested in the DAO, a hacker found a bug in the code that allowed him to make off with $50m of that stash of cash.
以太坊最终会成为一个有关编写无错误代码难度的警示小故事。以太坊的智能合约从投资者手中获取资金，并将其分配给其11,000名投票参与项目的成员。但是，在1.5亿个以太投入到分散自治组织（DAO）后，一名黑客在代码中发现了一个错误，使得他瞬间就从中获得了5000万美元的现金。
These days shady dapps are flourishing. At the time of writing the second-most-popular dapp using Ethereum’s networks is a kind of lottery whose rules are hosted on a site called Exitscam.me. This may be nothing more than growing pains. Yet Ethereum also suffers from many of the same built-in limitations as bitcoin. Its transaction rate is capped at about 14 per second. As with bitcoin, there are long-running plans to ease the jam, though it is unclear whether they will succeed.
近来，灰色性质的dapp蓬勃发展。使用以太坊的网络编写第二个最受欢迎的“dapps”的时机就类似买彩票，而规则则托管一个名为在Exitscam.me网站上。这更多地是成长的痛苦。然而，以太坊也遭受许多与比特币相同的内置限制。以太坊的交易率为每秒14个左右。与比特币一样，虽然尚不清楚它们是否会成功，但仍有长期计划能来缓解交易缓慢的问题。
For now, popular dapps can still clog the network. In late 2017 a game called “CryptoKitties” went viral on Ethereum’s blockchain. It involves smart contracts that create unique, cryptographically protected virtual cats which can be traded between users. Traffic on Ethereum’s network rose at least sixfold and many transactions failed.
目前，用户众多的“dapps”仍然受阻塞网络。 2017年末，一款名为“CryptoKitties”的游戏在以太坊的区块链上传播开来。它拥有智能合约，用以创建独特的，受密码保护的虚拟猫，还可以在用户之间进行交易。由于这个原因，以太坊的网络流量至少增加了六倍，许多交易都无法成功进行。
Despite such fiascos, the flexibility of its smart contracts has made Ethereum the platform of choice for all sorts of blockchain-powered experiments. It has also provided a means to pay for them, by issuing new cryptocoins which, instead of running on their own blockchains, piggyback on the Ethereum one. That has turbocharged an idea called initial coin offerings (ICOs), a form of crowdsourced fundraising that is becoming popular in the cryptocurrency world.
尽管经历过这样的惨败，但以太坟智能合约的灵活性使得以它成为各种区块链支持的实验的首选平台。以太坊还以发行新加密货币的方式为这些区块链实验提供了支付方式。 这些新发行的加密货币并不在自己的区块链上运行，而是寄生在以太坊里。这引发了一种叫做代币（ICO）的想法——一种众包筹款形式，在加密货币世界中有越来越多的人使用。
编译：韩晓曦
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