Introduction to Science, Experimentation, & Evolution PDF

What is science? A process that logically addresses questions about cause-effect relationships in nature Science considers past and current events Science can make logical predictions The proposed explanations must be testable and falsifiable  What science is NOT...

What is science? A process that logically addresses questions about cause-effect relationships in nature Science considers past and current events Science can make logical predictions The proposed explanations must be testable and falsifiable  What science is NOT Non-science: topics that can be logical and based on good reasoning, but fail to meet scientific criteria (CONPTT). Examples include religious beliefs, philosophy, personal opinions/attitudes, ethics, moral judgments. Pseudoscience: ideas portrayed as legitimate science by supporters, but fail to meet criteria. Ideas might be testable, but scientific method is not employed and ideas are held as unchangeable “beliefs”. Examples include Six Criteria of Science : Consistent, Observable, "CONPTT" Natural, Predictable, Testable, Tentative. Information taken from Steven Dickhaus (ENSI 89)  Consistency: The results of observations and/or experiments are reasonably the same when performed and repeated. 1. Green plants will grow towards a light source. 2. Walking under a ladder will cause bad luck. Observability: The event or evidence of the event, can be observed and explained. The observations are limited to the basic human senses or to extensions of the senses. 1. Some plants can eat meat. 2. Extraterrestrial beings have visited Earth. Natural: A natural cause (mechanism) must be used to explain why or how the event happens. 1. Green plants convert sunlight into energy. 2. People can walk through walls.  Predictability: Specific predictions can be used to make foretell an event. Each prediction can be tested to determine if the prediction is true of false. 1. Students who attend class do better than students who do not attend class 2. If you are a "Scorpio", your horoscope for today is "You'll be saying 'I feel rich !' Lunar position highlights back pay, refunds, correction of accounting error." Testability: the event must be testable through the processes of science, and controlled experimentation. 1. The Bermuda Triangle causes ships and planes to sink and disappear. 2. Dogs are more social than cats. Tentativeness: Scientific theories are subject to revision and correction, even to the point of the theory being proven wrong. Scientific theories have been modified and will continue to be modified. 1. The number of human chromosomes was once "known" to be 48, but is now considered to be 46. 2. We know that the world began about 6000 years ago, and nothing will change that.  In science, ideas are tested and many are disproved. Only those that we fail to disprove survive. Ancient Greeks: hypothesized that the earth was round Against many warnings that he would sail off the edge, Magellan sailed around the earth. (1) Science starts with observation: What do you see? What is already known? (2) Put forth a hypothesis… A hypothesis is a proposed explanation for an observable phenomenon (3) Design an experiment to test hypothesis (4) Collect and analyze data (5) Make a conclusion Lets test whether people can’t walk a straight line without a visual cue. http://www.youtube.com/watch?v=fA6pqvgUuO0  Experiments explore the relationship between variables A variable is: – Something that can vary in an environment or organism Which of the following are variables? – Body length in a fish – Sex in honey bees – The mass of an electron In a controlled experiment, one variable is altered and all others are kept the same  What is a controlled experiment? A scientific investigation in which both the control group and experimental group(s) are kept under similar variables (matched variables) except the factor under study (independent variable) so that the effect or influence of that factor can be identified or determined  Scientific control A scientific control is an experiment or observation designed to minimize the effects of variables other than the single independent variable (the  Why use a control? Controls give you a baseline to which you can compare the rest of the results It is the “zero” or starting point Controls are also used as a check for failures in an experiment – Positive versus negative controls Example of a controlled experiment: the Widowbird experiment Long-tailed widowbird – Small grassland bird of southern Africa Males have long tails! Tails likely hinder flight and escape from predators Why the long tails? Hypothesis: Males have The Experimental Design Manipulated tail length of males (poor guys!) – Control group: normal tail length – Two experimental groups - Short and Long tails Birds placed in similar  Data Collection and Results Counted number of female nests in each male’s territory Control Short tails Long tails Result: males w/ 1