To ensure that someone can possibly calculate new answers every day, the train conductor estimates the number of people participating in obtaining the questions and gradually increases the difficulty of the questions.
Above the Rules#
The neighboring village heard that there is a magical train that gives tips when the cargo is placed on the train. Everyone wants to try it out.
After the village chief looked at the rules, he didn't take the questions like everyone else, but studied the rules: "If I can control more than 50% of the people to calculate together, I can make the train generate according to my ideas. That means I can control the train and even swap the goods on the train or create items out of thin air..."
The neighboring village chief was excited about the idea and quickly returned to the village to call on all the villagers to calculate together. After explaining the pros and cons to the villagers, the whole village unanimously decided to become prosperous together.
The neighboring village chief put up a banner near the train: "Calculate the questions together, become rich together, include the village, include marriage."
The village chief quickly discovered this problem and followed suit, gathering all the people in the village to calculate together and enticing people from other villages who came to solve the questions to calculate together in his own village. He also tried various methods to prevent the number of people from exceeding 50%.
- POW adopts the "longest chain consensus" mechanism, which means that if you control 51% of the network's computing power, you have an absolute advantage in obtaining the right to record, can generate blocks faster, and have the right to tamper with blockchain data.
- This can also lead to double-spending attacks.
- The simplest understanding of the longest chain consensus is that if multiple people have the right to package at the same time, whoever reaches a chain length of 6 on their own node first will be recognized by the main chain.
- In reality, when the computing power exceeds 45% of the entire network, an attack may occur. The entire network resists through methods such as changing mining pools. (Because BTC, in essence, still needs a basis of trust. If BTC is controlled by anyone, its credibility disappears, its value disappears, and the entire network cannot function. Therefore, this situation rarely occurs and is mostly balanced by multiple parties.)
Double-Spending Attack#
This can be understood as follows: You first use 1 BTC from the public chain to buy a computer, and then secretly create a longer chain that indicates that this BTC was used to buy a phone, and broadcast this chain to the public chain. This way, you can spend 1 BTC twice.
- Double-spending and 51% attacks are actually very difficult to achieve and have rarely occurred in reality. When the Chashio mining pool approached 50% of the network's computing power, it was collectively resisted, and an announcement was made to exercise control.