Question

the double - slit experiment is a famous experiment that reveals the wave - particle duality of light and matter. when particles such as electrons are fired through two closely spaced slits, they create an interference pattern on a detection screen, indicative of wave behavior, but if one attempts to observe which slit the electron passes through, the interference pattern collapses, and the electrons behave like particles. this phenomenon, known as wave - function collapse, initially shocked the world due to its implications for our understanding of quantum mechanics—scientists explain that unlike macro - level interactions, the act of measurement itself alters the system, suggesting that
14 ◇ mark for review
which choice most logically completes the text?
① the interference pattern can be restored by removing the detection apparatus.
② the wave - function collapse is a common but avoidable consequence of measurement.
③ at the quantum level, there may not be a truly neutral observer.
④ the electrons behavior is determined solely by the experimental setup.

Explanation:

To solve this, we analyze each option:

• Option A: Removing the detection apparatus doesn't restore the interference pattern as the act of observation (not just the apparatus) causes collapse. Eliminate A.
• Option B: The text says the collapse is due to measurement altering the system, not that it's "avoidable". Eliminate B.
• Option C: The text states that measuring (observing) alters the quantum system, meaning an observer can't be neutral (since observing changes the system). This fits.
• Option D: The electrons' behavior changes with observation, so it's not "solely" the experimental setup (observation is part of the setup's effect, but the key is observation altering the system). Eliminate D.

Answer:

C. at the quantum level, there may not be a truly neutral observer.