Scientific Theories Overview

Scientific Theories

• Scientific theories explain the natural world and advance knowledge.
• They are the highest level of explanation in science.
• Thoroughly tested over time.
• Provide accurate explanations and predictions for many phenomena.
• Widely accepted by the scientific community.
• Supported by strong experimental and observational evidence.

Distinguishing Scientific Theories from Everyday Usage

• Common usage equates "theory" with uncertainty or a guess.
• In science, "theory" is the best explanation for how things work.
• Theories are tested multiple times by different scientists.
• They represent robust, working models of the natural world.
• Supported by multiple lines of evidence.
• Not static; can develop and change with new observations and reasoning.
• Can be disproven by new contradictory data.
• Example: Evolution by natural selection.

Developing a Scientific Theory

• A theory starts as a hypothesis—a proposed explanation.
• Hypothesis development relies on prior knowledge, evidence, logic, and scientific reasoning.
• Hypotheses require testing and experimentation.
• Theories differ from hypotheses in scope of explanation and amount of testing. Theories are more reliable because of their extensive evidence.
• A hypothesis becomes a theory through testing, refinement, and increasing evidence.
• Example: Einstein's theory of special relativity.

The Scientific Method

• Scientists don't always follow a strict sequence of steps.
• The scientific method is better described as a cycle.
• It encompasses various activities like:
  • Making observations
  • Formulating questions
  • Developing hypotheses
  • Testing hypotheses through experiments or investigations
  • Analyzing results and data
  • Drawing conclusions
  • Restarting the cycle when necessary

Using the Scientific Method in Everyday Life

• The scientific method is not limited to specialized research.
• Can be used to solve daily problems.
• Example: Locating a lost phone.

Characteristics of a Scientific Theory

• Testability: Confirmed through experiments or rigorous scientific investigations.
• Reproducibility: Other scientists achieve the same results following the same procedures.
• Replicability: Consistent results with the predictions when re-examining phenomena
• Simplicity: Preference for simpler theories, avoiding unnecessary concepts or objects.
• Consistency: Compatible with other widely accepted theories.

Fact vs. Theory

• Theory: Explains universal mechanisms across the natural world.
• Fact: Confirmed observation of a specific phenomenon or object.
• Theories are built upon scientific facts.
• Example: Atomic theory. Matter is made of atoms. Scientific observations support this.

Scientific Law vs. Scientific Theory

• Scientific law: Describes regular occurrences in nature.
• Do not explain why phenomena occur, just how they occur.
• Unlike scientific theories, scientific laws do not typically predict phenomena nor provide overarching explanations.
• Examples:
  • Law of gravity: Describes the acceleration of falling objects.
  • Law of independent assortment: Describes the separation of alleles during gamete formation

Scientific Theory Examples

• Plate tectonics: Describes Earth's crustal changes, explaining geological phenomena like earthquakes and volcanic eruptions.
• Big Bang theory: Explains the origins of the universe, supported by many observations from astronomers and astrophysicists.

Modifying Scientific Theories

• Theories often need revision as new technologies/observations emerge.
• Example: Atomic theory has changed over time as scientists gained a deeper understanding.
  • Early understanding of atoms was basic, later models incorporating subatomic particles.

Unifying Scientific Theories

• Combining different theories into a single explanation.
• Example: Electromagnetism. Electricity and magnetism, originally considered separate, were unified to create the theory of electromagnetism with the work of scientists like Oersted, Faraday, and Maxwell.