But there is a big issue standing in the way of this goal and that is scalability.

但是爲了實現這一目標，有一個很大的問題，就是可擴展性。

Let me give an example: the payment provider VISA processes on average around 4000 transactions

讓我舉一個例子：支付提供商VISA平均每秒約處理4000筆交易，而最高可擴展至6,5000筆。

per second and scale up to a maximum of 65,000.

而比特幣在目前區塊大小爲1 MB的情況下，每秒最多可以處理7筆交易。

Bitcoin on the other hand can handle up to 7 transactions per second with the current

不是幾万筆，而只是7筆！

block size of 1MB.

顯然主區塊鏈不是很可擴展的。

Not tens of thousands, but just 7!

但其實不一定要這樣。

Clearly the main blockchain isn't very scalable.

社區已經想出了一個新的技術，稱作“閃電网絡”，來解決可擴展性問題。

But it doesn't have to be!

關鍵的想法是，小型的日常交易 不必存儲在主區塊鏈上。

The community has come up with a new technique called the Lightning network to solve the

這可以避免每秒7筆的交易限制，也被稱為鏈下方法。

scalability issue's.

那麼它是怎樣工作的呢？

The key idea is that small, everyday transactions don't have to be stored on the main blockchain.

那麼讓我們來看一個例子吧，比方說每天早上Bob上班路上買一杯咖啡。

This avoids the 7 transactions per second limit and is also called the off-chain approach.

在區塊鏈上僅爲了一杯咖啡而創建一筆交易確實是過分了。

So how does it work?

他可能最終會支付比他的咖啡的實際價格多很多的費用。

Well let's take a look at an example, let's say that every morning Bob buys a cup of coffee

但是，Bob可以用閃電網絡與咖啡店建立一個付款通道。

on his way to work.

要做到這一點，咖啡店和Bob都要向“多重簽名地址”裏面存一定數量的比特幣。

Creating a transaction on the blockchain for a simple coffee is really overkill.

讓我們假設Bob存了0.05 BTC，而咖啡店沒有存，因爲他們不提供退款。

He might end up paying more fees than the actual price of his coffee.

這個多重簽名地址基本上就像一個只有在雙方都同意的時候纔能打開的保險箱。

However, with the lightning network Bob can setup a payment channel with the coffee shop.

當我們建立付款渠道時，我們也建立了一個餘額表，說明地址裏的資金應該如何分配。

To do that, both the coffee shop and Bob deposit a certain amount of Bitcoin in what is called

所以現在的餘額表顯示：“Bob會得到0.05 BTC，咖啡店將獲得0 BTC。“

a multi-signature address.

和他們存入時一樣。

Let's assume that Bob deposits 0.05 BTC and the coffeeshop deposits nothing, because

付款通道是在主區塊鏈上打開的，這樣就有了完全的透明度。

they don't offer refunds.

咖啡店老闆可以看到Bob確實存入了0.05 BTC，他們可以確保，當通道關閉時他們將會得到錢。

This multi-signature address is basically like a safe that can only be opened when both

現在這個通道是打卡的，Bob可以預訂他早晨的咖啡！

parties agree.

假設一杯咖啡的價格是0.001 BTC。

When we open the payment channel we also make a balance sheet that says how the funds in

爲了付這筆帳，鮑勃只需要改變餘額表。

the address should be distributed.

他從自己的餘額中減去了咖啡的價錢，並將其添加到咖啡店的餘額上。

So right now it says: “Bob will get 0.05 BTC and the coffee shop will get 0 BTC.”

所以現在是“Bob獲得0.045 BTC ，而咖啡店得到0.005 BTC“（爲什麼付了5杯的錢？）

The same as they deposited.

Bob 和咖啡店現在用他們的私鑰對更新的餘額表簽名，

Opening the payment channel happens on the main blockchain so that there is full transparency.

然後他們雙方都保留其一個副本，但他們不需要做其它事情。

The coffee shop owner can see that Bob has deposited 0.05 BTC and they can rest assured

Bob可以一直點咖啡，只要他在付款通道中還有餘額。

that they will get their money once the channel closes.

他們兩人可以在他們之閒建立幾十万筆交易。

Now that the channel is open, Bob can order his morning coffee!

這完全沒有限制，因爲這發生在主區塊鏈之外。

Lets say that a coffee costs 0.001 BTC.

但是所有的好故事都會結束。

To pay for it, Bob simply changes the balance sheet.

支付通道可以隨時由Bob或咖啡店關閉。

He subtracts the cost of the coffee from his balance, and adds it to the coffeeshop's

他們所要做的就是按照雙方簽名的最新的餘額表格，將其廣播到比特幣网絡中。

balance.

礦工們將會驗證餘額表中的簽名。如果一切都沒問題了，將會按照餘額表釋放資金。

So now it says that “Bob gets 0.045 BTC and the coffee shop gets 0.005BTC”.

這將在比特幣區塊鏈中創建一筆單一的交易。

Bob and the coffeeshop now sign the updated balance sheet with their private keys, they

所以閃電网絡可以顯著減少主區塊鏈上的負荷。

then each keep a copy of it but they don't do anything else with it.

它只需要在區塊鏈上進行兩筆交易：一筆是打開付款通道的，另一筆是關閉的。

Bob can keep ordering coffee's for as long as he has a balance in the payment channel.

這也是非常安全的。

Both of them can make hundreds of thousands of transactions between them.

系統確保只有最新簽名的餘額表可以用來解鎖資金。

There is really no limit because this happens away from the main blockchain.

而且因爲雙方都有已簽名副本的餘額表，他們在任何時候釋放資金，

But all good stories come to an end.

即使另一方不想繼續合作。

The payment channel can be closed at anytime by either Bob or the Coffee shop.

比如說：Bob不能持有這筆屬於咖啡店的押金，

All they have to do is take the latest balance sheet, which was signed by both parties and

反之亦然。

broadcast it to the Bitcoin network.

它並沒有在存在那裏。

Miners will then validate the signatures on the balance sheet and - if everything checks

你並不需要向每一個你需要付比特幣的人建立直接的支付通道。

out - release the funds according to the balance sheet.

你用网絡來傳輸你的幣就行了。

This will create a single transaction on the Bitcoin blockchain.

這是Alice，她是Bob的朋友。

So the lightning network can significantly reduce the load on the main blockchain.

他們之前已經在閃電网絡上交易過了，所以他們有個活躍的支付通道。

It only requires two transactions on the blockchain: one to open the payment channel and another

現在假設，Alice想買一杯咖啡。

one to close it.

她不需要和咖啡店建立一個直接的通道，她可以把錢轉給Bob，

It's also very safe.

然後由Bob將轉給咖啡 店。

The system ensures that only the latest signed balance sheet can be used to unlock the money.

並不需要爲每個人創建一個支付通道！

And because both parties have a signed copy of the balance sheets, they can release the

在閃電密語絡中，您的支付會試圖 尋找從A到B的路徑。

funds at anytime, even if the other doesn't want to cooperate anymore.

它試圖用最少的中閒結點和最低的費用來做到這一點。

So for example: Bob cannot hold the money hostage that belongs to the coffeeshop and

這進一步減少了區塊鏈上的壓力，但是它要求中閒節點在支付通道中有足夠的錢。

vice versa.

所以，現在你知道什麼是閃電網絡 ，以後它是如何工作的了。但是什麼時候才能真正實現呢？

It doesn't end there.

現在有一個用來驗證概念的實例在比特幣測試网絡上運行。

You don't need to open a direct payment channel with everyone you want to send bitcoins

我們還不知道閃電网絡什麼時候會讓每個人能用上，很可能在2018年會發生！

to.

這個視頻到此結束。

You can simply use the network to pass your coins around.

如果你喜歡它，點擊豎起大拇指的按鈕並訂閱。

Here is Alice, she's a friend of Bob.

非常感謝您的收看，下期視頻再見！

They've exchanged money on the lightning network before, so they have an active payment

channel.

Now let's say that Alice wants to buy a coffee.

Instead of opening a direct channel to the coffeeshop, she can transfer the money to

Bob, who will then transfer it to the coffee shop.

No need to create a payment channel with everyone!

In the lightning network, your payment tries to find a route from person A to person B.

It tries to do this with the least amount of intermediates and the least amount of fees.

This further reduces the strain on the blockchain but it requires the intermediates to have

enough money in the payment channels.

So, now you know what the Lightning network is and how it works, but when will it actually

go live?

Well right now there is a proof-of-concept implementation running on the Bitcoin testnet.

We don't know yet when it will go live for everyone, but chances are it happening in

2018!

So that was it for this video.

If you liked it, hit the thumbs up button and get subscribed.

Thank you very much for watching and I'll see you in the next video!