I am confused about miners being able to modify timestamp data within the header. I thought the only modifiable piece of data within the header was the nonce. I understand changing the Merkle root, through different transactions being included in a trial block, but how are timestamps modifiable? I thought the timestamps where reliant upon the sender, and when they pushed their transaction, is this incorrect?
I understand where the target value comes from now, much more so than last night. Now I'm wondering what happened if/when SHA-256 becomes compromised to some degree. Thanks for the input, goddog and achow101.
I'd still argue that it is doing work, in order to create a solution to a problem/question, but I do understand why that would be confusing terminology. Plus, it's clear that I understand very little about our protocol, so my arguments hold little weight.
the timestamp is choosen by the miner, it is another arbitrary data the miner can use. But there is a fixed range of values. It can not bee too much in the future or too much in the past.
The block time is a Unix epoch time when the miner started hashing the header (according to the miner). Must be strictly greater than the median time of the previous 11 blocks. Full nodes will not accept blocks with headers more than two hours in the future according to their clock.