Scientific Theory | Definition, Characteristics & Examples

• Law of gravity: Isaac Newton's law of gravity is a mathematical statement of the acceleration of falling objects based on their mass. The law does not explain why gravitational attraction occurs; it merely describes the behavior of objects subject to gravitational forces.
• Law of independent assortment: Mendel's law of independent assortment states that alleles for genetic traits get separated during gamete formation. When Mendel proposed this law, he did not have a theoretical explanation for how independent assortment happens. He simply knew that it was happening. Since he observed that it happened consistently, it became a scientific law. As with all scientific laws, the law of independent assortment is merely a statement of what happens, not how something happens.

Modification of a Scientific Theory

As time passes, theories are often revised. For example, as new technologies are developed, new observations are possible. Researchers can refine theories as a result of these discoveries. If new observations are greatly inconsistent with the predictions of a theory, then the theory may be discarded or altered.

Atomic theory is an excellent example of how ideas can be modified and improved given new data. Over the past two hundred years scientists have gained a deeper understanding of the complexity of atoms compared to original understandings.

• In the early 19th century, John Dalton described atoms as microscopic, indivisible particles, almost like tiny, unbreakable billiard balls.
• By the late 19th century, J.J. Thomson had identified negatively charged components of atoms called electrons
• In the late 19th and early 20th century, scientists observed other subatomic particles, protons and neutrons, which disproved Dalton's original conception of atoms as whole, indivisible particles.
• During the 20th century, the quantum mechanical behavior of electrons was introduced into atomic theory, resulting in our present-day understanding of atoms and subatomic particles.

Unification of a Scientific Theory

There are times when different theories are combined into a single explanation. Electromagnetism is an example of this. Electricity and magnetism were both well known to scientists during the early 19th century, and for the most part, they were treated as separate phenomena. However, Hans Oersted observed in 1820 that magnetism and electricity were interrelated. Oersted published his observations, leading to Michael Faraday's development of a unified theory of electromagnetism and James Clerk Maxwell's electromagnetic equations.

Scientific theories differ from scientific facts and scientific laws. Theories are tested explanations of general natural occurrences that can be applied universally, while scientific facts are verified observations of particular, specific phenomena or objects. Scientific laws describe some observable regularities of nature but do not attempt to explain why these regularities occur.

Theories are not static and unchanging. Scientists modify theories to accommodate new observations and supplementary reasoning. Different theories may be unified when phenomena previously thought to be unconnected turn out to be part of related processes. Researchers can also falsify theories if observations arise that are not consistent with the theories' predictions.