Because scientists are in the business of investigating nature, scientists function as:

A scientific finding is believed to be true until new evidence arises. This view is referred to as:

When Pasteur tested the hypothesis of spontaneous generation, he compared the ability of a sterilized growth medium (meat broth) to produce a population of bacteria in two different types of flasks. One had a simple neck open to the outside, and the other had a "goose neck" bend that also was open to the environment. Pasteur expected that bacteria would appear in the flask with the standard neck. In this experiment, the standard neck flask served as a/an: