For the first time in 5 years, it takes 2 hours to mine a block on the Bitcoin network

According to Bitcoinist on October 2, the Bitcoin network mined an abnormally slow block, which took a total of 119 minutes to mine. This abnormal phenomenon occurred despite the fact that the mining power of the Bitcoin network has recently hit a new high.

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The probability of the Bitcoin network generating slow blocks is extremely low

In the Bitcoin network settings, miners mine a new block every ten minutes. So far, the block time of the Bitcoin network has remained within the predetermined time and has only fluctuated slightly.

But the block with a block height of 597273 really took miners a lot of time and computing power.

After the previous block was mined, it took miners 119 minutes to mine a block with a block height of 59727319.

This has only happened 10 times in Bitcoin’s history, with the last time this happened in May 2014.

Assuming that the average block time of the Bitcoin network is 10 minutes, the probability of generating this block is only 0.000679%.

— Antoine Le Calvez (@khannib) September 30, 2019

It is very rare for a block to take that long to be mined. As of October 1, the Bitcoin network's hash rate was 89 trillion hashes per second. This means that in 119 minutes, miners consumed a lot of electricity and computing power to mine it.

The next block was mined in less than a minute. Since some miners try to use probability optimization to mine, the probability of this block appearing should be extremely low.

There are currently two explanations for the appearance of this block. The first is that miners did not reach a consensus on the block. The other explanation is that the Bitcoin blockchain may have split, but the fork monitor did not detect the occurrence of this event.

Bitcoin lacks an emergency difficulty adjustment mechanism

In fact, other networks have also experienced long block times, such as Bitcoin Cash. The main reason is that there are too few miners participating in mining, and the network has not adjusted the mining difficulty. The Bitcoin network adjusts the mining difficulty every two weeks, and the mining difficulty of the network is currently at its highest level in history.

Just before block 59727319 was mined, the Bitcoin network suddenly lost 30% of its hash rate. In addition, the Bitcoin network has lost more than 1,400 nodes in the past three months, indicating that the decentralization of the Bitcoin network has decreased and the possibility of potential security risks in the network has increased.

The Bitcoin network has proven many times that it will not easily fall into a “mining death spiral.” However, the Bitcoin code does not have a more flexible way to respond to sudden changes in mining difficulty.

So far, Bitcoin mining activity has been steadily increasing and has not seen a significant decline.