Consistency

I've touched on the idea that separate observers each experience "their own reality", but when they come together and compare notes, they will always find their experiences are mutually consistent. This is the Law of Consistency.

Basically, if all that you can be certain of is only what you know and what you observe, then everything else is defined only by probabilities. Some quantum mechanics junk says that it can't be known any more than that, I think. But a separate observer may make observations of what you can't observe, meaning that they have a different definition of what is real and what is only probability.

When you and the other observer share information, you gain knowledge. What was previously just probable is now actual. Probability waveforms collapse, and this propagates "backward through time", in that observations of the present depend on observations of the past, and what you know to be real now makes what it is based on in the past, real in the past.

So you have your reality, and the other has their reality, and where those overlap is a shared reality. This reality will always be consistent. Your shared reality will have a common shared history. The events you shared will appear the same under any observation. At least, they will within the bounds of causality. For example, the chronology of causally unrelated events may not be agreed upon by separate observers. This may be a major clue about the Law of Consistency, but I'll put it aside for a moment.

Consistency appears on the surface to be a source of weirdness, in that there is an appearance that some mechanism "corrects" or "sorts out" observers when they come together, or somehow simultaneously restricts separate observers while they are apart. On the other hand, consistency may be what saves us from the otherwise weird aspects of quantum mechanics.

Take the example of entangled particles. When both particles are considered by a common observer, there are some "weird" aspects apparent, like "spooky action at a distance". Consistency requires that the observation of other laws, such as conservation of spin, is observed for both particles. However, the observer of only a single particle sees no weirdness. They see only a single particle behaving as a single particle. The expectation that a message can be passed from an observer of one particle to the observer of the other is false, because only an observer of both particles can observe an effect that depends on both particles (such as any effect of entanglement). This again may appear weird, because the common observer can include an observer who gains information from one or both separate particles at a later time. That is, I may gather the results from 2 separate observations, and notice that they display weird aspects of entanglement, but neither I nor anyone else will observe any effects of entanglement until we've made observations of (that is, gained information about) both particles.

And so Consistency simultaneously displays weirdness, and makes it not weird (because it is by definition consistent). That is to say, it is only because things must be consistent that they appear to be weird, in cases like this. The weirdness cannot be exploited in ways that break laws (FTL message passing breaks the law of Causality, notably).

Trying to exploit entanglement involves trying to make things inconsistent, but the only way to attempt that is to separate the observers, and in doing so, consistency between the observers no longer applies, and the effects of consistency (such as entanglement) can no longer be observed.