The scientific method attempts to explain the natural occurrences (phenomena) of the universe by using a logical, consistent, systematic method of investigation, information (data) collection, data analysis (hypothesis), testing (experiment), and refinement to arrive at a well-tested, well-documented, explanation that is well-supported by evidence, called a theory. The process of establishing a new scientific theory is necessarily a grueling one; new theories must survive an adverse gauntlet of skeptics who are experts in their particular area of science; the original theory may then need to be revised to satisfy those objections. The typical way in which new scientific ideas are debated are through refereed scientific journals, such as Nature and Scientific American. (Depending upon the area of science, there are many other journals specific to their respective fields that act as referees.) Before a new theory can be officially proposed to the scientific community, it must be well-written, documented and submitted to an appropriate scientific journal for publication. If the editors of these prestigious publications accept a research article for publication, they are signaling that the proposed theory has enough merit to be seriously debated and scrutinized closely by experts in that particular field of science. Skeptics or proponents of alternative or opposing theories may then try to submit their research and data, while the original proponents of the proposed theory may publish new data that answers the skeptics. It may take many years of often acrimonious debate to settle an issue, resulting in the adoption, modification, or rejection of a new theory. For example, the Alvarez Meteorite Impact theory (a 6-mile wide meteorite struck the earth 65 million years ago, ending the Cretaceous Period and causing extinction of the dinosaurs), was first proposed in 1979, and took about 10 years of debate before winning over the majority of earth scientists.
A successful scientific inquiry may culminate in a well-tested, well-documented explanation (theory) that is supported overwhelmingly by valid data, and often has the power to predict the outcome of certain scenarios, which may be tested by future experiments. There are rare examples of scientific theories that have successfully survived all known attacks for a very long time, and are called scientific laws, such as Newton's Law of Gravity.
Below is a generalized sequence of steps taken to establish a scientific theory:
The classic scientific method where a convenient laboratory experiment may be devised and observed often cannot be done in the earth sciences. This is because most of earth and geological phenomena are too big (earthquakes, volcanic eruptions) or too slow (mountain building, climate change) to be observed easily or replicated; the earth itself is the "laboratory." Also, because many of the events analyzed by geologists occurred long ago, they often "working backwards" - that is, they start with the conclusion (a rock or fossil), and try to work out the sequence of past events that occurred over geologic time.
Limitations of the Scientific Method
The scientific method is limited to those phenomena which can be observed or measured. For example, what existed prior to the Big Bang and the known universe is outside of the realm of science to investigate.
Science is good at explaining "how things work" but not necessarily for explaining "why do such things exist" or "for what purpose." (Science does not really explain why the Universe exists.)