The rabbis of the Talmud molded Jewish law and practice, but they also took note of scientific ideas and the world around them. They made observations, tested their hypotheses, and classified their results. This was, in large part, because it helped them know how to perform the mitzvot most accurately. In order to apply the mitzvot of the Torah to the world–the chief project of the Talmud–the rabbis had to know the world.
A survey of the Talmud turns up frequent discussions of botany, anatomy, biology, zoology, astronomy, medicine, magic, astrology (which would have been regarded as "science"), and even rudimentary chemistry. Although they were not engaged in sophisticated scientific calculations, the rabbis demonstrated a remarkable awareness of various branches of scientific study.
Religion and science are often seen as being in conflict. In general, the former makes claims based on faith; the latter on reason and method. But because the religion of the Talmud is concerned with practice more than dogma, this dichotomy is rarely addressed.
Driven by practicality and their own curiosity, there were times that the rabbis did what would be called science for its own sake, as a means to understand the way the world operated. This may have helped them do mitzvot more accurately, but that was not always their chief concern.
One of the most important endeavors for the rabbis in talmudic times was setting the calendar and the holidays. This depended on a significant understanding of astronomy, and many of the talmudic sages became experts in this field. Using observations of the new moon, Samuel bar Abba was able to calculate and determine the calendar and the dates of holidays many years in advance, and even accounted for leap years (Rosh Hashana 20b).
Judaism is often described as an embodied religion–the practices depend on the physical performance of the commandments. The rabbis tried to become intimately aware of the ways that the body works, in order to more fully understand how to observe the commandments.