(a) What is meant by the term molecularity? (b) Why are ter-molecular elementary reactions so rare? (c) What is an intermediate in a mechanism?
Lecture 1 The Scientific Method and Scientific Principles 1. What is science Science is a process of discovering how the physical world works. i.e. how things relate to each other 1) Process primarily inductive vs. deductive Inductive = leads to “possible” or “probable” connections among things Deductive = leads to “certain” conclusions 2) Deductive reasoning: Reasoning from cause and effect 3) Inductive reasoning Generalization: consistent observations of something in a subset(sample) is construed to be true of the whole set(population) 2. What is animal science Animal science is one of the oldest “sciences” as it began when man first began domesticating animals about 15,000 years ago. 3. The scientific method 1) Observe some aspect of the universe. Natural phenomenon 2) Invent a tentative description, called a hypothesis (educated guess,) that is consistent with what you have observed. Hypothesis It is not a question. It is the answer to that question. Basis of scientific knowledge A proposed idea that explains the relationship among some observations or evidence Must be testable Hypotheses that successfully pass testing → Theories Prove by many scientist with a long time. It is not a question. A guess! Ex: Ladybugs are a good natural pesticide for treating aphid infected plaints. 3) Use the hypothesis to make predictions. 4) Test those predictions by experiments or further observations and modify the hypotheses in the light of your results. 5) Repeat steps 3 and 4 until there are no discrepancies between theory and experiment and/or observation. Why Human errors Outliners Natural variability Reinforce the validity Decrease margin of errors “Theory” means different things to different audiences To scientists: a theory represents certainly and is a unifying explanation for a broad range of observations. To the general public: a theory implies a lack of knowledge or guess Scientists’ acceptance of theory is provisional. Possibility always remains that future evidence will cause a theory to be revised. 4. Scientific Principles 1) Repeatable 2) Obtained by same and other observers 3) Objective (vs. subjective) (have a standard) 4) Adequate numbers (n) (sample size)