A scientific theory is a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation. As with most (if not all) forms of scientific knowledge, scientific theories are inductive in nature and aim for predictive power and explanatory force. The strength of a scientific theory is related to the diversity of phenomena it can explain, and to its elegance and simplicity (Occam’s razor). As additional scientific evidence is gathered, a scientific theory may be rejected or modified if it does not fit the new empirical findings- in such circumstances, a more accurate theory is then desired. In certain cases, the less-accurate unmodified scientific theory can still be treated as a theory if it is useful (due to its sheer simplicity) as an approximation under specific conditions (e.g. Newton’s laws of motion as an approximation to special relativity at velocities which are small relative to the speed of light). Scientific theories are testable and make falsifiable predictions. They describe the causal elements responsible for a particular natural phenomenon, and are used to explain and predict aspects of the physical universe or specific areas of inquiry (e.g. electricity, chemistry, astronomy). Scientists use theories as a foundation to gain further scientific knowledge, as well as to accomplish goals such as inventing technology or curing disease. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge. This is significantly different from the common usage of the word “theory”, which implies that something is a conjecture, hypothesis, or guess (i.e., unsubstantiated and speculative).