A hypothesis attempts to answer questions by putting forth a plausible explanation that has yet to be rigorously tested. A theory, on the other hand, has already undergone extensive testing by various scientists and is generally accepted as being an accurate explanation of an observation. This doesn’t mean the theory is correct; only that current testing has not yet been able to disprove it, and the evidence as it is understood, appears to support it.
A theory will often start out as a hypothesis -- an educated guess to explain observable phenomenon. The scientist will attempt to poke holes in his or her hypothesis. If it survives the applied methodologies of science, it begins to take on the significance of a theory to the scientist. The next step is to present the findings to the scientific community for further, independent testing. The more a hypothesis is tested and holds up, the better accepted it becomes as a theory.
The theory of evolution, for example, is supported by a plethora of scientific evidence in the form of cosmological, geophysical and archaeological research data, to name just a few relevant fields. Scientists have not only traced the evolution of species through skeletal records, but the earth itself, our solar system, the stars and galaxies can be “dated” through various scientific methods. This evidence appears to track the universe back about 13.7 billion years to a “Big Bang” event.
While there appears to be no end to the evidence supporting the theory of evolution, it is still only a theory. Theories, no matter how well accepted, are always subject to change as new knowledge comes to light. Einstein’s Theory of Relativity, for example, explained the world on a massive scale, but broke down when it came to the world of the infinitesimally small. This famous theory was augmented more recently by superstrings’ M-theory, which very nicely united the four known forces in the universe in one elegant mathematical equation. M-theory exotically predicts we live in a world of ten dimensions, plus one for time, for a total of 11 dimensions. While many aspects of M-theory make it difficult to test, the mathematical perfection of this theory has lent it strength in scientific circles.
A current hypothesis of great importance is that of dark energy. Scientists can calculate how much mass is present in the universe, yet physical matter – matter made from atoms – makes up only four percent of the total. Dark matter is believed to make up another twenty percent, leaving about seventy-six percent unaccounted for. Enter the hypothetically summoned dark energy to fill the gap. There are a few competing candidates for dark energy with research underway. However, one of the problems is difficulty in detecting it. So even while its interaction with gravity on a massive scale is sufficient to cause the universe to rapidly expand outwards, in the lab detecting it is a bit like checking for a light breeze using a weathervane full of gigantic holes. Nevertheless, as scientists untangle the mystery of the missing mass, the answer will one day rise from mere hypothesis to generally accepted theory.