Obsolete blocks sometimes appear. But two together is rare.
Bitcoin had two obsolete blocks in the blockchain on Tuesday (29), according to an analysis by BitMEX Research. The two obsolete blocks were found at the time of blocks 650.473 and 650.491, respectively.
This is not a common occurrence. One obsolete block happened in July, and two more came in August. Although not particularly dangerous, there are some ways in which they may slightly affect the network. But it is rare that they appear so often.
Obsolete blocks do not indicate anything disastrous in the blockchain, but they do indicate poor network propagation. In other words, an obsolete block „results in wasted work, less proof-of-work, which can make the network cheaper to attack,“ a BitMEX Research spokesman told Decrypt.
He added that obsolete blocks can „benefit larger mining companies by increasing the pressure of centralisation.
What are obsolete blocks?
Obsolete blocks are valid blocks that almost become part of the blockchain – but they narrowly lose. The Bitcoin Revival blockchain operates on an underlying rule that wins the longest chain. As several competing chains receive blocks, they increase in length, all competing to become the longest. During this competition, some blocks on a shorter chain can be left behind, creating obsolete blocks.
One of the potential risks of obsolete blocks is that they can cause twice as much expenditure. On 27 January 2020, a double spending of US$3 occurred on an obsolete block, the first obsolete block in the Bitcoin blockchain since October 2019. But it is very unlikely that it was a purposeful attack.
It is unlikely that double spending as a result of an obsolete block has a malicious intent. Double spending usually does not offer much financial reward, making it a vulnerability far from attractive to evildoers. In addition, the distributed nature of blockchain technology means that the success of an attack would depend on controlling 51% of the network’s mining hash rate, making these types of attacks almost impossible.
„Obsolete blocks are very rare, so it’s probably not worth an attacker’s while trying to make a double expense if they show up,“ BitMEX Research told Decrypt.
There are many potential attacks to worry about in the world of cryptomorphs, but the possibility of obsolete blocks is not one of them.