18UNIT1: PHYSICALSCIENCEANDYOUFigure 1.17: Three different models for Earth and the solar system that were believed at different times in history.scientific method- a process of learning that begins with a hypothesis and proceeds to prove or change the hypothesis by comparing it with scientific evidence.The Scientific MethodLearning bychanceAt first, humans learned about the world by trial and error, trying one thing at a time, like a small child attempting to open a jar. She will try what she knows: biting the lid, pulling on it, shaking the jar, dropping it … until, by chance, she twists the lid. It comes off. She puts it back and tries twisting it again — and the lid comes off again. The child learns by trying many things and remembering what works.Learning by thescientific methodIt takes a long time to learn by randomly trying everything. What is worse, you can never be sure you tried everything. The scientific methodis a much more dependable way to learn. The Scientific Method1.Scientists observe nature, then invent or revise hypothesesabout how things work.2.The hypotheses are tested against evidence collected fromobservations and experiments. 3.Any hypothesis which correctly accounts for all of the evidencefrom the experiments is a potentially correct theory.4.A theory is continually tested by collecting new and differentevidence. Even a single piece of evidence that does not agreewith a theory causes scientists to return to step one.Why the scientificmethod worksThe scientific method is the underlying logic of science. It is basically a careful and cautious way to build a supportable, evidence-based understanding of our natural world. Each theory is continually tested against the results of observations and experiments. Such testing leads to continued development and refinement of theories to explain more and more different things. The way people learned about many things great and small, to the solar system and beyond, can be traced through many hypotheses (Figure 1.17).