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What Is a Hypothesis?
A scientific hypothesis is a proposed explanation for an observable phenomenon. In other words, a hypothesis is an educated guess about the relationship between multiple variables. A hypothesis is a fresh, unchallenged idea that a scientist proposes prior to conducting research. The purpose of a hypothesis is to provide a tentative explanation for an occurrence, an explanation that scientists can either support or disprove through experimentation.
A Basic Example of a Hypothesis
Forming a hypothesis is a key component of the scientific method. Consider an everyday example of how you might create a new hypothesis and test it using the steps of the scientific method:
- Observation: Your car won’t start.
- Question: Is the battery dead?
- Hypothesis: If the battery is dead, then jumper cables will help it to charge, and the car will start.
- Experiment: You hook jumper cables up to the battery.
- Result: The car starts.
- Conclusion: Your battery was dead, and your hypothesis was correct.
What Is a Theory?
A scientific theory is an explanation for a natural phenomenon that is widely accepted among the scientific community and supported by data. Scientific theories are confirmed by many tests and experiments, meaning theories are unlikely to change. While the word “theory” is commonly used outside the scientific world to describe a simple hunch, scientists use the term to describe a broadly accepted explanation for an occurrence.
The purpose of a theory is to establish a general principle that clearly explains certain phenomena. While a theory is not a prediction, scientists may use theories to help make a prediction about an unexplained aspect of the natural world.
4 Examples of Scientific Theories
Below are a few of history's most revolutionary theories. Remember, what makes these claims theories is that they are backed by scientific evidence.
- The Big Bang Theory: The Big Bang Theory claims that the universe started as a small singularity 13.8 billion years ago and expanded suddenly.
- The Heliocentric Theory: Nicolaus Copernicus' theory demonstrates that Earth travels around the Sun.
- The Theory of General Relativity: Albert Einstein's theory claims that massive objects (like the Earth) cause a distortion in space-time, which is experienced as gravity. This theory actually supplanted one of the most famous scientific laws, Newton's Law of Universal Gravitation.
- The Theory of Evolution by Natural Selection: Charles Darwin's theory—most succinctly summarized as “survival of the fittest”—explains how gradual changes in populations of organisms over time leads to the emergence of traits that allow those organisms to survive.
Theory vs. Hypothesis: What’s the Difference?
A hypothesis proposes a tentative explanation or prediction. A scientist bases their hypothesis on a specific observed event, making an educated guess as to how or why that event occurs. Their hypothesis may be proven true or false by testing and experimentation. A theory, on the other hand, is a substantiated explanation for an occurrence. Theories rely on tested and verified data, and scientists widely accepted theories to be true, though not unimpeachable.
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