About your analogy - quantum cloning may not be allowed by laws of nature. That would make any consciousness unique at any point in time.
Also I feel the experiment suggests split brains would most likely become 2 very different (new?) entities with different behavior after losing integrity.
Not analogous. Sons are practically obligated by family (and indirectly by the immediate society) to marry even against their will for keeping the tradition. Also females were considered unfit to get married after a certain (very young) age creating a pressure on girl's family to find a groom as early as possible. People created pseudo scientific and religious basis for enforcing these.
It was a social evil has rightly been banned but slavery was both a social evil and individual maliciousness on part of people who partook in it - and there were a few black folk too in that group who were selling their own people. No society 'mandated' slaverer to sell people as a way of life. There were always other professions if it didn't fit well with their conscience. No one would make your life hell for not actively selling slaves by making you into a social outcast.
For 1 because your trading existence in that universe would change the future which you can't account for. Your activity influences decisions of other HFTs in real time whereas with a static history you're claiming to be able to trade without perturbing the markets.
Well not at all scales. Gravity at quantum scales is still not well understood.
Also the only way to claim it works as expected at any scale is to test it out. This allows scientists to claim that the theory checks out at this scale too.
Who is everyone that you refer to ? One thing I can certainly say is that US isn't the only one that interferes. China is a growing power with intention to dominate. We're already aware of the cyber attacks that have originated from China. It makes sense that their intervention goes beyond hacking for weapon blueprints.