According to the Oxford online dictionary, science is "the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment". Scientific research is based on observation, hypothesis and most importantly – criticism. Any scientific theory must be refutable by a conceivable event, i.e. one must be able to design an experiment whose results can contradict and thus refute the theory in question. The following video introduces us to the scientific methods and to the principles on which it is based:
This video was produced by potholer54
The scientific method can be described as a flowchart: first, we collect data through observation, leading to the conception of a hypothesis. In order to validate our hypothesis and turn it into a theory, we must test it by experimentation, keeping in mind potential biases and performing all necessary controls. After analyzing our findings we formulate a conclusion and describe a unifying model, which is our theory. The more subsequent observations that validate our theory, the stronger it becomes. It is possible for a single phenomenon to be described by several theories. After we have formulated our theory it must be reviewed and refereed by other scientists, who may suggest additional experiments in order to test our theory. If our theory is accepted it will be published in a scientific journal. As mentioned, any theory must be refutable, which means that there must be a conceivable event that would contradict it. Hence, any scientific theory can be annulled or at least modified at any given moment. This is a critical point, as many scientists are keen to prove their colleagues' theories false and instead have their own theories accepted. Such a system ensures scientific progress.
A prominent example is "the ultraviolet catastrophe" – a late 19th century paradox. At the time, scientists knew how to measure the radiation emitted from a black body, but all attempts to calculate the expected radiation gave rise to infinite amounts. The reason for this was that these calculations were based on classical physical theory, according to which electromagnetic radiation behaves as a wave with continuous levels of energy. This implied that the greater the frequency of the electromagnetic wave, the greater the radiation emitted by a black body at that frequency. Adding up all these infinite frequencies yielded ever-growing levels of energy. Since the problem refers to high frequencies, i.e. at the ultraviolet range, the paradox has been termed "the ultraviolet catastrophe".
In order to solve this problem, German physicist Max Planck hypothesized that electromagnetic radiation is not a continuous form of energy but rather can be emitted only in quantized form, i.e. only in certain discrete magnitudes (quanta). At the time, Planck had no reason to raise this hypothesis other than the fact that it enabled him to solve the ultraviolet catastrophe paradox. He demonstrated that when factoring his assumption into the calculation of the radiation emitted by a black body, the results match the empiric measurements. Later on, through his introduction of the photoelectric effect, it was Albert Einstein who suggested how Planck's hypothesis can be validated by experiment. For this Einstein was awarded the Nobel Prize in Physics in 1921. Planck's hypothesis was the foundation for a new branch of physics – quantum mechanics. It was suddenly realized that classical theory, which until then was considered perfectly accurate, was in fact flawed. Further hypotheses and more experiments were carried out in the next few years to give rise to quantum theory. Several years later, upon his publication of his theory of relativity, Einstein revealed yet another aspect in which classical theory failed.
So this is the scientific method: there are no certainties and no proofs, and at any moment any theory can be refuted or modified, giving rise to a new theory. This can be very frustrating for scientists who have based their whole research on an outdated theory, but it is the only way by which our scientific knowledge and understanding can progress, for the well-being of all of humanity.