What principle states that gravity can contaminate a sterile object if a contaminated liquid flows over it?

The principle that gravity can contaminate a sterile object through the flow of a contaminated liquid is accurately captured by the idea of "contamination by gravity." This concept emphasizes that when a liquid—potentially carrying pathogens—flows over a sterile surface, gravity plays a crucial role in allowing the contaminants to come into contact with that surface.

When a sterile object or area is exposed to a liquid that is not sterile, the force of gravity can facilitate the downward movement of this liquid and its contaminants, thereby leading to possible contamination of the sterile object. This principle is especially important in settings where maintaining sterility is critical, such as in surgical environments or laboratories.

In contrast, the other options do not accurately reflect the principles of contamination and sterility. For instance, the idea that a wet surface can make something sterile is misleading, as moisture can actually promote microbial growth. Additionally, stating that gravity has no effect on sterility contradicts the fundamental understanding of how contaminants can spread. Lastly, the notion that only physical touch can contaminate ignores the various ways that objects can become contaminated, including through airborne particles, liquids, and other indirect means.