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.
比特幣愛好者喜歡講，與黃金一樣，加密貨幣的供應是有限的。比特幣的協議規定，最多隻能開採2100萬個比特幣，而最後一批比特幣將在22世紀中期開採完。比特幣人士認為，與普通貨幣不同的是，固定的供應能確保它不會受到通貨膨脹的侵蝕。
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.
不過，即便比特幣的供應有可能是有限的，加密貨幣的供應卻並不非如此。比特幣協議是開源的，因此無法阻止其他人照抄這個想法。他們已然這麼做了，而且是興致盎然。到目前為止，有數千種不同的加密貨幣面市。與比特幣一樣，這些加密貨幣對投機者頗有吸引力。例如，支付機構瑞波（Ripple）發行的瑞波幣（XRP），從今年1月不到1美分的價格上漲至將近3.46美元（此後又下跌至0.35美元左右）。雖然加密貨幣漲跌的幅度各不一樣，它們價格的變動趨勢往往是連動。當比特幣上漲時，這些的“山寨幣”也會上漲，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.
一些山寨幣則遊走在灰色地帶。有好幾個項目實際上被稱為“龐式幣”（PonziCoin），而有一個項目在2014年似乎實現了承諾，在吸引足夠多的買家進入之後，很快就在封盤前打廣告，稱有高達120％的年回報率。有些項目則是笑話：Dogecoin源於個互聯網動圖，是在2013年互聯網上風靡一時的石布狗。即便如此，Dogecoin在2017年的價格也隨著其他加密貨幣的價格飆升，從0.0002美元上漲到0.017美元，增長了85倍。目前流通的Dogecoin的名義價值2.67億美元。
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，一些山寨幣正努力嘗試修復一些對比特幣的認知問題。其中之一就是比特幣不是真正的匿名。如果一堆比特幣能與用戶的真實身份綁定，區塊鏈就會顯示他每次接收比特幣的交易。（這幫了邦調查局特工一大忙，他們在2013年逮捕了絲綢之路網站的創始人羅斯·烏布利希特（Ross Ulbricht）。該網站此前是一個網絡黑市，有很多交易通過比特幣進行。）
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是三種旨在更為用戶保密。尤其是Monero在互聯網的灰色角落裡，迅速成為比特幣的替代品，很受歡迎。同時，諸如Basis，Carbon和Tether等“穩定幣”試圖遏制加密貨幣吸引投機者的波動性。Tether表示它的幣與美元掛鉤。目前它約有25億個幣流通。2017年，該公司承諾聘請外部審計機構來證實它確實有真實現金支持這些幣。可是，今年3月仍然沒有進行審計，該聲稱與其聘用的審計機構在審計方法上沒有達成一致。
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，陷入嚴重經濟困境的委內瑞拉政府宣佈創建石油幣——一種據稱由該國龐大的石油儲備所支持的加密貨幣。它的出現一部分原因是為了繞開美國的制裁。委內瑞拉總統尼古拉斯·馬杜羅（Nicolas Maduro）聲稱，在石油幣面市當天，以稀缺的美元計算，預售額就達到了7.35億美元。
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，許多加密貨幣根本就不流通。跟蹤垂死加密貨幣網站Deadcoins.com列出了大約900個被創造者或用戶拋棄的加密貨幣。
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).
在比特幣的最初構想中，最出名，也最有趣的轉折是以太坊。 比特幣愛好者Vitalik Buterin在2015年提出這個創意。它的主要創新是允許計算機代碼 ——名為“智能合約”——駐留在其區塊鏈上。該代碼運行在預先定義的環境之中，並以以太坊的原生加密貨幣“以太”作為小額支付，用補償運行該程序電腦的擁有者。這些程序可以相互交互，使得構建複雜分佈式區塊鏈“dapps”（分佈式應用程序）成為可能。
Into the ether
進入以太
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.
從理論上講，這種方式使得以太坊能比比特幣成為一個更大眾化的系統。比特幣區塊鏈旨在完成一項工作：成為電子現金的分類賬。可以編寫一個以太坊“dapps”來做同樣的事情，也可以有其他用途。例如，Golem是今年推出的由以太坊支持的項目，用來創建一個“去中心化的超級計算機”，用於獎勵用記讓他們的計算機的閒置算力為其他人工作。這致使人們興奮地討論以太坊，認為以太坊本身成為了一種“無法關閉的世界計算機”，甚至是“互聯網 3.0”，其中最重要的是可以構建去中心化的的，由用戶控制的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.
對於一個擔憂互聯網巨頭的權力的世界來說，這可能會是一個極具吸引力的前景。以太坊的智能合約最開始的規模不大，涉及自動化賭場和彩票等領域，之後就變得更加壯大了：如成立於2016年的分散自治組織（DAO）就規劃為自動化投資基金。
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.
以太坊最終會成為一個有關編寫無錯誤代碼難度的警示小故事。以太坊的智能合約從投資者手中獲取資金，並將其分配給其11,000名投票參與項目的成員。但是，在1.5億個以太投入到分散自治組織（DAO）後，一名黑客在代碼中發現了一個錯誤，使得他瞬間就從中獲得了5000萬美元的現金。
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.
近來，灰色性質的dapp蓬勃發展。使用以太坊的網絡編寫第二個最受歡迎的“dapps”的時機就類似買彩票，而規則則託管一個名為在Exitscam.me網站上。這更多地是成長的痛苦。然而，以太坊也遭受許多與比特幣相同的內置限制。以太坊的交易率為每秒14個左右。與比特幣一樣，雖然尚不清楚它們是否會成功，但仍有長期計劃能來緩解交易緩慢的問題。
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，用戶眾多的“dapps”仍然受阻塞網絡。 2017年末，一款名為“CryptoKitties”的遊戲在以太坊的區塊鏈上傳播開來。它擁有智能合約，用以創建獨特的，受密碼保護的虛擬貓，還可以在用戶之間進行交易。由於這個原因，以太坊的網絡流量至少增加了六倍，許多交易都無法成功進行。
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.
儘管經歷過這樣的慘敗，但以太墳智能合約的靈活性使得以它成為各種區塊鏈支持的實驗的首選平臺。以太坊還以發行新加密貨幣的方式為這些區塊鏈實驗提供了支付方式。 這些新發行的加密貨幣並不在自己的區塊鏈上運行，而是寄生在以太坊裡。這引發了一種叫做代幣（ICO）的想法——一種眾包籌款形式，在加密貨幣世界中有越來越多的人使用。
編譯：韓曉曦
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