Scientific language tends to use predominantly the agentless passive voice while literary language tends to use more active voice. If you are writing a science report, the emphasis is on the action rather than the agent (or actor).
For example: The cup was broken (says what happened but doesn't say who did it). In order to get the agent of the action into the sentence, you must include the information in a prepositional phrase.
or: David broke the cup (tells immediately who performed the act).
The distinction is important because each discipline favours language that fits with their values. In writing about literature, we use the active voice because the characters or the agents of an act are as important as the act itself. In writing about science, we wish to eliminate the agents because the action and not the scientist or the agent is what is really important.