Use blocks to keep time.

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Editor’s note: Since the birth of Bitcoin and other virtual currencies, it is destined to be a process of mixed reputation. Just like the proverb: half of human nature is divine and half of animal nature. This sentence perfectly embodies the characteristics of Bitcoin. Its decentralized design mechanism generally arouses people’s infinite reverie and hope; but in the process of implementation, it is mixed with too much human greed about wealth and desire. The “Animal Spirit” of Keynes was vividly embodied. “When you stare into the abyss, the abyss also stares at you. In this article, the author cites classics and deeply analyzes the nature of Bitcoin. He believes that timekeeping devices have changed civilization more than once. As the American social philosopher Lewis Mumford said As pointed out in 1934: “The key machine in the modern industrial age is a clock, not a steam engine.” Today, it is another timekeeping device that is changing our civilization: clocks, not computers, are the real key to the modern information age. Machine, and this clock is Bitcoin. The original title Bitcoin Is Time, author dergigi.

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Decentralization time

Time has passed everything. ——Aeschylus (525 BC-456 BC)

Time and order have a very close relationship. As Leslie Lamport (a well-known computer scientist in the United States, well-known for inventing key distributed technologies and receiving the Turing Award in 2013) pointed out in his 1978 paper “Time, Clock, and Event Sequencing in Distributed Systems”. “The concept of time is the foundation of our way of thinking. It is from eventsDerived from the more basic concept of the order of occurrence. Without a central point of coordination, the seemingly intuitive concepts of “before,” “after,” and “at the same time” would collapse. In Lamport’s words: the concept of “occurs before” defines an unchanging partial sequence of events in a distributed multi-process system.

To put it another way: if people are not allowed to be responsible, who should be responsible for the time? If there is no central frame of reference, how can there be a reliable clock?

You might think that solving this problem is easy, because everyone can use their own clock. This only works if everyone’s clock is accurate, and more importantly, everyone does not cheat. In an adversarial system, relying on a personal clock would be a disaster. Moreover, due to the existence of the theory of relativity, the time of the clock in different spaces cannot be kept consistent.

Do a thought experiment and imagine how you can cheat the system if everyone is responsible for timing themselves. You can pretend that the transaction you are sending is actually yesterday, but it was delayed for some reason, so you will still have all the money you spent today. Because asynchronous communication exists in every decentralized system, this situation is not just a theoretical thought experiment. News will indeed be delayed, the timestamp is inaccurate, and due to the effect of relativity and the natural speed limit of our universe, it is very difficult to distinguish the order of things without a central institution or observer.

“Who is there? Boom, knock on the door”

—— an asynchronous joke

In order to better illustrate the impossibility of this problem, let’s look at a specific example. Imagine that both you and your business partner can use your company’s bank account. You do business all over the world, your bank account is in Switzerland, you are in New York, and your business partner is in Sydney. For you, today is January 3rd and you are enjoying a beautiful Sunday night in the hotel. For her, it is already Monday morning, so she decided to buy breakfast with a debit card from your common bank account at a cost of 27 yuan. The fee is 27 yuan, and the available balance is 615 yuan. The local time is 8:21 in the morning.

At the same time, you are about to use another debit card linked to the same bank account to pay for your accommodation. The cost is 599 yuan. The available balance is 615 yuan. The local time is 5:21 pm.

So, at the same moment, you all swiped your cards, what happened? (Dear physicist, please forgive me for using “same moment”-we will ignore the effect of relativity and the fact that there is no absolute time in our universe for the time being, and we will also ignore the fact that the concept of synchronous events does not really exist. To explain the bit The currency is complicated enough!).

Your bank’s central ledger may receive a transaction before another transaction, so one of you will be lucky, and the other will not. If these two transactions happen to arrive at the same time, say within the same millisecond, the bank will have to decide who will spend the money.

Now, if there is no bank, what will happen? Who decides who is the first person to swipe the card? What if it is not just the two of you, but hundreds or even thousands of people coordinating? What if you don’t trust those people? What if some of them want to cheat, such as turning the clock back to the original point to make people think they spent a few minutes in advance?

A time-related tool is needed to establish a canonical order and execute a unique history without any central coordinator.

——Giacomo Zucco, Discovering Bitcoin (2019).

This problem is the reason why all previous digital cash users needed a centralized registry. You always have to believe that someone can correctly identify the order of things, and you need a centralized party to save time.

Bitcoin solved this problem by reinventing time itself. It says no to “seconds” and yes to “blocks”.

Use blocks to keep time

The emperor’s fight is the style of time,

Exposing the lie and letting the truth come to light,

Imprint the years and stamp the past,

Watch the night and wake up at dawn,

Punish the wicked until he repents,

—— William Shakespeare, “Luke Liss Humiliation” (1594)

All clocks rely on periodic processes, which we can call “ticks”. The “tick” sound of the clock is essentially the same as the molecular and atomic hum of our modern quartz clocks and cesium clocks. Something is oscillating, or oscillating, we only need to calculate these oscillations until they add up to one minute or one second.

For large pendulum clocks, these swings are long and easy to see. For smaller and more professional clocks, special settings are requiredPrepared. The frequency of the clock, its beating frequency depends on its usage.

Most clocks have a fixed frequency. After all, we want to know the time precisely. However, there are also some clocks whose frequency is variable. For example, the metronome, its frequency is variable, you can set it before making it tick. Once the metronome is set, its rhythm will remain unchanged, while Bitcoin’s time will change every tick, because its internal mechanism is probabilistic. However, the purpose is the same: to keep the music alive so that the dance can continue.

Clock beat frequency

Old-style clock ~0.5 Hz.

Metronome ~0.67 Hz to ~4.67 Hz

Quartz watch 32768 Hz

Cesium-133 atomic clock 9,192,631,770 Hz

Bitcoin 1 block (0.00000192901 Hz* to ∞ Hz**).

* The first block (6 days)

** Timestamps between blocks may show as negative deltas.

The fact that Bitcoin is a clock is hidden in full view. In fact, Satoshi Nakamoto pointed out that the Bitcoin network as a whole is a clock, or in his words: a distributed timestamp server.

In this paper, we propose a method to solve the double-spending problem, using a peer-to-peer distributed timestamp server to generate a calculation proof of the transaction time sequence.

—— Satoshi Nakamoto (2009)

Time stamp is the fundamental problem to be solved. This can also be seen by studying the references at the end of the Bitcoin white paper. Of the total eight references, three are about time stamps:

How do I get a time stamp to a digital file, author: S.Haber, W.S.Stornetta (1991)

Improving the efficiency and reliability of digital time stamping, D. Bayer, S. Haber, W.S. Stornetta (1992)

Secure time stamp service with minimum trust requirements designed by H.Massias, X.S.Avila and J.-J.Quisquater (May 1999)

As outlined by Haber and Stornetta in 1991, digital timestampsIt is about the actual procedure of calculation, so that the user (or opponent) cannot retrospect the date or forward the date of the digital file. Contrary to physical files, digital files are easily tampered with, and this change does not necessarily leave any obvious traces on the physical media itself. In the digital realm, forgery and tampering can be perfect.

Due to the plasticity of information, time stamping digital files is a complicated process. The native solution will not work. Take a text document as an example. You cannot simply add a date to the end of the document. Because everyone, including yourself, can simply change the date in the future. You can also fabricate the date at the beginning.

Time is a causal chain

In an extreme view, the world can be seen as having only connections and nothing else.

—Tim Berners Lee, Weaving the Web (1999).

Making up dates is a common problem, even in non-digital areas. The method called “newspaper authentication” in the kidnapping community is a general solution to the problem of arbitrary timestamps.

Time proof

This is feasible because newspapers are difficult to forge and easy to verify. It is difficult to fake, because the front page of the newspaper today mentions yesterday’s events. If the photos are from a few weeks ago, the kidnappers would not be able to predict these events. Through the agency of these incidents, this photo proved that the hostages were still alive on the day the newspaper was published.

This approach highlights a key concept when it comes to time: causality. The arrow of time describes the causality of events. Without causality, there is no time. Causality is also the reason why cryptographic hash functions are so critical when it comes to time-stamped files in cyberspace: they introduce a kind of causality. Since it is actually impossible to create a valid cryptographic hash if there is no document in the first place, a causal relationship is introduced between the document and the hash: the relevant data exists first, and then the hash is generated. In other words: if there is no computational irreversibility of a one-way function, there will be no causality in cyberspace.

A precedes B

With this causal component, people can come up with some solutions to create a series of events, from A to B to C, and so on. In this sense, the secure digital time stamp allows us to enter the field of digital history from an eternal place in the ether.

Causality fixes events in time. If an event is determined by some previous events and determines some later events, then this event is firmly clamped in the historical position.

——Bayer, Haber, Stornetta (1992).

There is no doubt that causality is the most important in economic calculations. A ledger is nothing more than a manifestation of the economic calculations of multiple cooperative participants, so causality is essential for each ledger.

We need a system for participants to agree on a single history […]. The solution we propose starts with a timestamp server.

—— Satoshi Nakamoto (2009)

The fascinating thing is that all the puzzles that make Bitcoin work already exist. As early as 1991, Haber and Stornetta proposed two schemes that made it “difficult or impossible to generate false timestamps.” The first relies on a trusted third party; the second, more complex “distributed trust” scheme, does not. The author even pointed out the inherent problems of the causal chain of trust events and the conditions needed to rewrite history. In their words, “The only possible deception is to prepare a false timestamp chain, long enough to exhaust the most suspicious challengers that people expect.” Similar attack vectors exist in Bitcoin today, in the form of It is a 51% attack (more on this in a later chapter).

One year later, Bayer, Haber, and Stornetta, based on their previous work, proposed to use trees instead of simple linked lists to link events together. The Merkle tree as we know it today is simply to deterministically create an efficient data structure of a hash value from multiple hash values. For timestamps, this means that you can efficiently bundle multiple events into one “tick”. In the same paper, the author proposed that the distributed trust model introduced in 1991 could be improved through repeated “World Championships” to determine a single “winner”.The generated hash value is widely published in a public place, such as a newspaper. Sound familiar?

We will see that the original newspaper is also the second element of thinking time: an excellent way of unpredictability.

Translator: Di Kewei

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The magical Internet currency, why is it said that Bitcoin is time? (Two)

The magical Internet currency, why is it said that Bitcoin is time? (Three)

The magical Internet currency, why is it said that Bitcoin is time? (Four)