Time Travel #1

Some things I have learned and have been thinking about regarding time travel:

1. You cannot traverse your origin world line. This means that if you traverse time, you wind up in either a slightly or wildly different reality from the one you left. Most things may be the same, but enough will be different that actions you take in the place you traveled to will not carry over to your original worldline. What I take from this bit is that there is a world where communism is the norm, and one each where every mad idea, as well as many we have never heard of, which grew into a movement, actually won. There's a world where the third reich took place, where it failed, et cetera.
2. While someone could not manipulate events on their own worldline, what they could do is simply move into the past of another worldline. This would be like a situation where I went back in time, patented a few key inventions regarding computing and networking specifically long before IBM or anyone else was capable of doing so, and reshaped the computing future -- in that worldline, which would not be an exact replica of the one I left -- to one where my ideals and my vision were the dominant mode by the time the 90s and 2000s rolled around.
3. John Titor may have begun as a hoax, but consider that such a well documented hoax would be a magnet for people who may be able to take action on any actual messages delivered by time travelers. Therefore even if it were a hoax, and the traveler knew that most people considered it a hoax, a quick "key word" if you will, if you wanted to communicate to a lot of people in short order, would be to call yourself by that name. There were more than one persons identifying as John Titor, after all, and they said they were working together and had met.
4. As a technologist, I have to believe that some elements of the John Titor story must be fictional -- for instance, the ability to imitate a mainframe computer system would only be important in a world where IBM had achieved maximum dominance, and Microsoft went completely unchallenged, etc. While this worldline exists, certainly, it does seem less likely that this worldline would reach the ability to time travel while such stifling conditions were the case. Innovation happens in chaotic times when anything is actually possible. A future where IBM and Microsoft were virtually in charge of worldwide computing would likely not yield a workable time travel solution for many more decades than alternate ones, and it seems that a culture which would abide as much as that would have several more severe problems. All-out luddism would seem more likely under circumstances like that.
5. As a blockchain enthusiast, I'm aware that the blockchain represents the one clear and identifiable way for time travelers to prove themselves. Because future data added to a public ledger is entirely unpredictable, a verifable hash from a future block which is soon to pass can be inserted into a past block, therefore the time traveller has proven they are able to see blocks "before" they happen. At this point, the first responsible message for a time traveler to deliver would be patches to the blockchain which would hopefully enable it to be more tamper resistant to motivated travelers. This all sounds insane, but in legacy systems not only would such thefts be easily possible, they would never even be notable. There are a few science fiction novels to be written around this subject alone. What if someone went back further in history and created the blockchain earlier? In any case, as stated earlier, tampering with the blockchain would only be a risk when travelers intended to stay in our worldline. Presumably this is already happening, and has always been happening. Beacuse if time travel exists, which it has to exist, then it has always existed, in the way that electricity always has, but we have not always been able to make use of it.

I think I'll be writing more on this subject as time goes on. It certainly fascinates me enough to spur the writing of some fiction.