How Observations Can Challenge Existing Scientific Theory

Instructor: Lisa Roundy

Lisa has taught at all levels from kindergarten to college and has a master's degree in human relations.

New observations can contradict existing scientific theories. This lesson will explain what happens when new evidence demonstrates that an existing theory is incomplete or incorrect.

Science in Action

Have you heard of Sir Isaac Newton? You know, that guy who had an apple fall on his head and subsequently discovered gravity - or so the story goes. Newton came up with some important information that we call the Newtonian Laws. It sounds like he is a pretty important guy! Would you dare to question his laws of motion? Well, that is exactly what Albert Einstein did.

Einstein's theory of relativity explained how the Newtonian laws of motion did not remain true when objects traveled at or near the speed of light. Einstein is really smart! However, when it was observed that his ideas didn't apply to extremely small particles, the theory of quantum mechanics was born.

A scientific theory is a tested explanation of why things happen, and is accepted to be true. This knowledge has been through rigorous testing that demonstrates it is reliable explanation of a phenomenon. If this is true, why do scientific theories continue to evolve? Because science is an ongoing process. As new observations are made, new ideas are developed to explain them.

Incomplete Theories

Our example of Newton, Einstein, and quantum mechanics is an example of the modification of an existing theory. Newton wasn't wrong. He just didn't have enough information. His ideas still hold up when we apply them to a falling apple or dropping our car keys. Likewise, Einstein's work wasn't overturned by the discovery of quantum mechanics. Each of these new ideas simply added to what we had already learned.

This is because the theories of Newton and Einstein were incomplete theories. Incomplete theories aren't wrong, but they do not apply to all situations. This is usually because the scientists don't have enough information to expand on the theory at the time it was formed. How much information do you think Newton had about gravity anywhere other than the earth in the 1600s?

Sir Issac Newton and Albert Einstein
incomplete theories

Erroneous Theories

We have seen how scientific theories can be incomplete, but most scientific knowledge holds up over time. However, on rare occasion scientists simply make mistaken assumptions and develop erroneous theories. Erroneous theories are theories that are incorrect. The discovery of new evidence will cause them to be rejected. This is just another part of the process of gaining knowledge.

The existence of the Martian canals is example of an erroneous theory that was considered correct by scientists not too long ago. An Italian astronomer named Giovanni Schiaparelli observed through a telescope what he believed to be a system of canals on the planet Mars in 1877. Scientists began to map these canals and speculate on their origins. Some even suggested they were built by unknown intelligent life.

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