1. Limitations of Science
Unit 1
Methods of Science:
Hypothesis
Law
Theory
Model
Limitations of Science

2. Read Section 1.2 prior to viewing the slides.
Section 1.2: Science: Reproducible, Testable, Tentative, Predictive, and Explanatory

3. Topics for Unit 1 Basic characteristics of science (1.2)
Hypothesis – testable and reproducible
Law – summary of many observations
Theory – tentative attempt to explain observations
Model – attempt to explain abstract ideas with more familiar scale examples
Limitations of science – why don’t we always know the answer?

4. Hypothesis A hypothesis is an educated guess that is testable
Hypotheses (plural of hypothesis) are tentative explanations of phenomena that can be tested by further experimentation
Example: If a plant receives fertilizer it will grow larger than a plant that does not receive fertilizer.

5. Testable vs. Untestable Hypotheses
The ability to test a hypothesis is a key element of its viability.
A testable hypothesis is one for which experiments may be designed to determine absolutely whether the hypothesis is false. Such a hypothesis typically involves some sort of quantitative (numerical) determination.
An untestable hypothesis is one for which no determination may be made as to its validity. Examples of untestable data include emotions, perceptions, etc.
The fertilizer/plant hypothesis on the previous page could be tested if the experiment is well designed – both watered equally, same sunlight, same seed stock, etc.

6. Law A law is a brief summary of large amounts of scientific data
A law does not attempt to explain why something happens – it simply states that it does
A law is universal – under the stated sets of conditions it has always been found to be true
Examples: The law of the conservation of mass, the law of gravity, the law of conservation of energy

7. Theory
A theory provides a detailed possible explanation as to why something is observed
Theories are tentative – they can be modified or discarded based upon new evidence
Theories provide predictive capability
Examples: Theory of Relativity, Kinetic-Molecular Theory

8. Model
A model attempts to explain abstract phenomena with tangible approaches
A model is often used to help picture the description of a process provided by a theory
Example: The processes in a gas can be envisioned as similar to billiard balls hitting each other – this lends a tangible visualization to the kinetic molecular theory

9. Interaction of Hypothesis, Law, Theory, and Model
Sometimes you may get the perception that these concepts are explored in a certain order, for example:
Observation → Hypothesis → Theory
In reality, though, there is no hard and fast rule as to the order in which these concepts are considered in scientific work.

10. Limitations of Science
It might seem that with the usually perceived “cold, hard fact” view of science that everything would have an absolute answer.
This is not the case due to the fact that science cannot control all of the variables.
Example: Consider man-made global warming, which is widely accepted now, but not by everybody. The number of variables to be understood is immense.