Modern science is confounded by quantum physics. Things that don't exist are represented by waves. Waves present a diffraction pattern that is unique when they pass through a double slit. When an observer is added these waves get converted through some process to the characteristic of particles. Particles are reality. They exist. They exist because they were observed (created?). A wave is an alternative universe that has the possibility or probability of existing at some future or past time.

Now you take Harry Truman's actions in 1948. If they existed then they did so before I came on earth. In a sense nothing that happened before I was born ever existed or the details of that existence might be other than the history books report. When I observe something I make it concrete. The manner in which I observe and record are what brings these observation into present day reality.

Just a little background. If you look at history through this lens there is less chance of being influenced by other people who try to control your observations (and beliefs) for their own ends (and their own creations). You will also understand how important it is to notice things or not to take notice of things.

Not taking notice is something you always have an interest in. If someone presents you with a notice in a non-official manner you don't have to accept that notice. Or you might consider the notice to be a new contract offer and either accept that offer, refuse it (in the nature of a dishonor) or perform a counter-offer. The counter-offer is an honorable way to cancel a notice/offer. An example of this is the bailiff stating "all rise". If you don't feel like agreeing with this notice/offer you raise your hand and ask "Is it ok if I stand on one leg?" in the manner of a counter-offer. You give him a second to consider and then state "nevermind" and keep your seat. By this statement you cancel your counteroffer. Your first statement (the counter-offer) cancelled his notice/offer.