Nondeterminism.

A property or a state of an object is nondeterministic when it has no real value until measured. QM showed that, at the quantum level, observers can't detect something without disturbing it, so the act of measuring is what forces a property to take a value.

As said, emissions and detections are necessary parts for any interaction, so any observer is part of the reality it detects, because it's making it happen. An observer is merely a bunch of absorption points, so they force reality to manifest around them (they “bend” spacetime, as explained earlier). When we place a detector somewhere, we aren't just intercepting carriers “in flight”, our operations (and the rest of the universe configuration) create the conditions that “got the journey started”. In some way, the emission point got “linked” to our detector by our actions. What we call “the future” is part of the carrier's instantaneous experience when detected, so the future we talk about is, in fact, always in the past. In this sense, they “always knew” our detector would be there. But the “wormholes” that connect the emission point to our detector wouldn't exist without it in place. They'd be different wormholes, with histories that fulfil the conditions to reach other absorption points in the universe.

Anything we can perceive is conformed as a spacetime process, so nothing we can see is made of “fixed values”. Fixed properties are just recurrent or structured fluctuations. Besides, we always need at least two events to define a relation, a process or an interval, so our knowledge about anything existing out there is always at least one spacetime unit old. This seems to be a small interval, but quite literally, the universe we see each time is completely brand new, made from information carriers never detected before by any other observer.