In science, the purpose of testing is to see if hypotheses and theories are applicable to real-world principles. In many cases, these theories come from the extrapolation of abstract principles, which means that they may or may not work out in real life.
Some examples of questions that appear as hypotheses but require testing include whether cooking oil can power a modified diesel engine or whether a new medication is effectiveness for treating a particular condition or disease. In research studies, simple observations of experiments are not sufficient as they are too subjective. However, providing facts that are statistically able to be tested and analyzed is a way to resolve a theory or hypothesis.
Even though science is ostensibly an objective discipline, researchers hold opinions and stick to their ideas even in the face of contradictory evidence. Research and testing allow scientists to test their own ideas, as well as those of others, to pursue answers that either confirm or rule out the ideas under analysis. Even when proven, no scientific idea becomes an ironclad fact, but it can become a theory that leads to further research. As theories build on one another, the scientific community makes progress in its various disciplines.