The block difficulty formula we saw earlier uses a 10-second threshold to make sure that the difference between the time a parent and child block mines is in is between 10-20 seconds. But why is it 10-20 seconds and not some other value? And why there is such a constant time difference restriction instead of a constant difficulty?
Imagine that we have constant difficulty, and miners just need to find a nonce to get the hash of the block less and equal to the difficulty. Suppose the difficulty is high; then, in this case, users will have no way to find out how long it will take to send ether to another user. It may take a very long time if the computational power of the network is not enough to find the nonce to satisfy the difficulty ...
