Why the ETH PoW fork is not legitimate from a technical perspective

I see many friends often confuse various "forks" and why ETH PoW is not orthodox from a fork perspective. Today I want to popularize a little concept.

As the name implies, blockchain is a chain of blocks. New blocks are connected to old blocks without stopping. If we calculate time in seconds in the real world, the world on blockchain calculates time in blocks as the smallest unit.

There are two kinds of forks in the world:

1. A fork caused by network desynchronization.

2. A fork caused by a divergence in versions.

Let's talk about the first one, the fork caused by network problems. This is a very common phenomenon that happens every day. For example, when two miners solve the problem almost at the same time and pack a new block, whose block is eligible to receive the old block? Forks occur naturally.

Generally speaking, miners will think that the first block they calculate is the legitimate one. However, they are afraid that two miners may calculate it almost at the same time, for example, a few milliseconds apart, and then add the delay of broadcasting in the network. Then naturally, there will be two groups. Someone received block A first, and someone received block B first.

At the same time, new blocks are received

To solve this problem, the industry has developed the "longest chain principle", which stipulates that if a blockchain forks at a certain height, then the block of the chain with the longer chain will be meaningful, and the shorter one will be discarded.

As shown in the figure, starting from the fork height, two miner groups began to compete in computing power, and all other miners had to choose sides. Because it is a brute force calculation of hash, the party with stronger computing power can usually calculate it faster. But in theory, there is also a possibility that the weaker party can be lucky enough to overtake.

Computing Competition

The winner earns all the block header rewards + transaction fees, while the loser gets nothing and wastes electricity.

Of course, in order to solve this problem, ETH has specially designed uncle blocks. Uncle is the younger brother of the father, but the uncle has no son. It allows the loser to get a little compensation and avoid some miners from fighting to the death.

If one party is malicious, it is a 51% attack. If both parties are not malicious, it is a normal fork. This is also the reason why exchanges require that tokens be deposited after a certain number of blocks.

Then, as shown in the figure, the longest chain becomes the main chain, and the network fork crisis is over.

The winner becomes the orthodox main chain

Now let’s talk about the second type, which is the fork caused by version differences.

Theoretically, ETH has forked many, many, many times, most of which are due to system version upgrades. For any forks caused by version upgrades, the longest chain principle does not apply. The longest chain principle is only applicable to solving network synchronization problems.

This is further divided into hard forks and soft forks.

If the whole network agrees to the hard fork caused by the upgrade, no new forked chain will be born. It is actually a complete replacement of the old chain by the new chain. The representative case is Ethereum's "London Upgrade", which is called an upgrade, but is actually a London fork. The London Upgrade brought EIP-1559 (burning of handling fees), but no new chain was generated. This is like the Qing Dynasty basically inherited the territory of the Ming Dynasty, and the Republic of China inherited the territory of the Qing Dynasty.

EIP1559 is a standard hard fork upgrade

However, if the community does not reach a consensus on the version upgrade, it will cause a split. For example, the ETC fork, the ETC and ETH chains are completely separated. The former is a version that has not been rolled back due to hackers, while the latter is a version that has. The two versions have differences and do not recognize each other. This is similar to North Korea and South Korea, which used to be one country, but now have completely become two countries and do not recognize each other.

ETC and ETC exist at the same time without interfering with each other

Therefore, hard forks are risky and cannot guarantee that the entire network will agree every time. Therefore, the Bitcoin world prefers soft forks, which have much smaller risks.

What is a soft fork? It means that although the version has changed, it can be upgraded or not, and everyone is still in the same network. Everyone knows that each state in the United States has its own laws, but they all follow the US Constitution. A soft fork is like a state in the United States introducing new regulations, which do not need to be adopted nationwide and will not cause division.

The most famous soft fork of Bitcoin is Segwit, which can remove part of the witness information to save Bitcoin block space without destroying 1MB and affecting security. As shown in the figure, if you agree with Segwit, you can upgrade, and if you don't agree, you don't have to upgrade. Although different versions of clients have differences, they can still mine together.

Soft fork: new and old versions can coexist

Soft forks are very concerned about the issue of "forward compatibility", while hard forks cannot be "forward compatible". Therefore, you can see that Bitcoin's reforms "seem" to be small, while Ethereum's reforms are drastic. This is because soft forks are a great test of the wisdom of core developers.

Friends who do software development may have a deep understanding of how difficult it is to want to add new features while keeping the old version in use. This is like dancing with shackles on your feet. It is very difficult to design a solution that has the best of both worlds. But Bitcoin has done it, using a lot of political trade-offs and development wisdom. Each soft fork design is very ingenious and amazing.

The reason is that Bitcoin is a public chain with an absolutely stable "fiscal policy". This feeling gives people a very reassuring feeling. Bitcoin pursues perfection in this aspect. In another 10 or even 100 years, Bitcoin will not be much different from today, just like real gold. In the next 100 years, the US dollar may disappear, but gold will not.

On the Ethereum side, Vitalik is still alive, and Ethereum does not pursue ultimate security, but seeks to break through the impossible triangle, so it takes risks every time to upgrade hard forks. You know, hard forks can easily cause the community to split. ETC in the past, ETH PoW today.

According to previous experience, as shown in the figure, PoS Merge should have been a hard fork upgrade similar to the previous one, and no new chain would have been created, directly inheriting the original version. At the same time, no one has ever asked about the ownership of USDT and USDC before.

It turned out to be a technical upgrade

However, the ETHPoW team is determined to conduct another hard fork upgrade at the same height of PoS Merge. This upgrade removes the difficulty bomb, etc. Here is a common mistake: the ETH PoW fork is not the original PoW chain of ETH. Many people mistakenly think that it is as shown in the following figure, one goes straight and the other turns left.

If this is the case, the legitimacy of ETH PoW is unquestionable.

Commonly Misunderstood Situations

However, the original PoW chain of ETH should be the chain with the difficulty bomb, that is, the PoW chain with "no client upgrade". PoS ETH is a new chain with "upgraded client". And ETH PoW is actually also a chain with "upgraded client"! Therefore, the actual situation should be as shown in the following figure, one turns left, one turns right, and no one goes straight.

The real situation, one goes left, one goes right, no one goes straight

Therefore, the actual situation is: ETH PoS and ETH PoW are actually new chains generated by hard forks, but they just happen to be at the same height, and the real ETH PoW original chain will die due to the difficulty bomb.

Therefore, ETH PoW is also weak in terms of legitimacy. In other words, if it forks today, it is completely fine to choose a different height than PoS Merge. So why does it have to choose the same height as PoS ETH? The answer is obvious to everyone.

Some people may ask, Todd, why do you want to clarify these things? I think that each chain is actually a country. If you live in a country, you must understand its legitimacy and system. Since it starts with 0x, as a citizen of the ETH world, it is natural to get to the bottom of it.

Consensus determines the ceiling of a chain. If it loses its legitimacy, it will also lose a lot of consensus.