Intensity gamma ray background

A factor that is uncontrollable by the experimenter might nevertheless be controlled by some other forces. Incident gamma ray background intensity, fluctuations in the levels of the oceans, barometric pressure, and phase of the moon cannot be controlled by the experimenter, but they are controlled by the Laws of Nature . Such factors are usually relatively constant with time (e.g., barometric pressure over a short term), or vary in some predictable way (e.g., phase of the moon). 

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