Ok so if you can't see it then how do you really know anything about the effect or behavior on the unmeasured side? Isn't this dependent on the particular interpretation used, such as the Copenhagen Interpretation for instance? I mean what really is the "collapse of the wave function"? Ah I sense that you are not completely satisfied with this codified evasion of a deeper causal answer. If so, you have good reason. Quantum mechanics simply says that the particle "flavor" was indeterminate before it was measured. We must simply take this interpretation (as empty of causality as it is) as an article of faith. The Sorce Theory interpretation is quite different. The states of the particles are NOT indeterminate at any time whatsoever. They are perfectly determinate systems, fluctuations or disturbances in the so-called "quantum vacuum" which can be described mathematically as a zero-energy superfluid. Such a "particle" is a structured positive or negative density/pressure gradient--a soliton or vortex with complex and specific properties due to harmonic equilibration of the input energies within the immediate environment. When the particles are created in the confluence of the engaging energy systems, a determined complex fluid-dynamic interaction takes place in which the two emergent measurable products (particles) possess distinct properties relating to each other which are entirely dependent on the interaction process itself and not the measurement process which happens later. The "entanglement" happens in the "creation" event and not in the measurement or the subsequent collapse. In the positron and electron pair production, for instance, the "photon" of the required energy simply splits its charge-balanced wave-system into its equal and oppositely charged components which, in a photon of the proper energy, are the positron and electron. The electron charge and the positron charge were already present in the wave (photon) in the first place, they had simply balanced each-other out previous to being split (because a photon has no net charge). Now how do you know the other side would show a different behavior without doing the two different measurements simultaneously? And how do you know that the act of measurement itself hasn't influenced the particle to measure the property in question thus making it incompatable with the different measurement selection??