Chapter 2: The World of Science

1. Chapter 2: The World of Science

2. 2.1: Scientific Explanation • Scientific Explanation describes how something works, or why something happens • But how do scientist form scientific explanations? • Scientist use methods such as • Researching information • Designing experiments • And making models to form scientific explanations

3. Florida Disaster • Jan 28, 1986: Challenger Space shuttle launched from Kennedy Space Center • 73s later, the Challenger exploded • Scientist and Engineers reviewed all the data records. • They carried out many test and experiments • They concluded that the joint between the two lower segments of the right solid rocket booster did not work correctly. • http://www.youtube.com/watch?v=j4JOjcDFtBE

4. What is the Basis for Scientific Explanation? • Scientist cannot make a claim unless they have EVIDENCE to support it. • Empirical Evidence: is the data and observations that have been collected through the scientific process Scientists often use graphs to analyze the evidence collected during an experiment. This graph shows how many radish seeds sprouted over time at two different temperatures.

5. Evaluating • Different scientists might interpret the same evidence differently. • For this reason scientist must evaluate the quality of each scientific explanation. • Sometimes the explanations are based on opinions. • An opinion is an idea that may be formed from evidence but has not been confirmed by evidence.

6. 2.2: Scientist and Society • Sometimes society wont accept a scientific discovery. This can cause a controversy. • Galileo Galilei • In 1610 he published his discoveries which supported the heliocentric model, this model showed that the sun, not earth was the center of our solar system

7. Society didn't agree with this, so in 1616 all books that supported this model were banned. • In 1632 Galileo wrote a book supporting this model. As a result, he was tried, found guilty and had to live the rest of his life under house arrest. • In time Galileo’s work led to an acceptance of science as a way of explaining the natural world

8. 2.3: How Science Changes Scientific Knowledge changes as a result of new evidence or new interpretations of existing evidence. • In 1905 Einstein was able to show how mass and energy were related. • He stated that mass could be converted to energy • A similar reaction happens with the sun and stars. • Every second about 4.5 million tons of the sun’s mass is converted to energy.

9. How is a Scientific Law Different from a Theory? • Scientist do not accept a new explanation after just one successful experiment. Rather an explanation is tested repeatedly as many scientist try to apply it to their work. • Sometimes a large set of related observations can be connected to a single explanation. This can lead to the development of a scientific theory. • Scientific Theory is a well tested explanation for a wide range of observations or experimental results. • Further testing can prove a theory to be incorrect

10. How is a Scientific Law Different from a Theory? • Have you ever heard the expression: what goes up must come down? • When scientist observe the same result in specific circumstances, they may arrive at a scientific law. • A Scientific Law is a statement that describes what scientists expect to happen every time under a particular set of conditions. • Unlike a theory, a scientific law describes an observed pattern in nature without attempting to explain it.

11. 2.4: Models as Tools in Science • In science model is any representation of an object or process • Scientist use models to understand things they cannot observe directly. • For example, scientist use models as reasonable representations of things that are either very large like the Earth’s core or very small like an atom.

12. What is a System? • Many things you see or use are systems • A system is a group of parts that work together to perform a function or produce a result • All systems have input, process and output • Input: is the material or energy that goes into a system • Process: What happens in a system • Output: material or energy that comes out of the system. • Some systems have feedback which is output that changes the system in some way.

13. How are Models of System Used? Scientist use models to understand how systems work. They also use models to predict changes in a system as a result of feedback or input changes. A Basic Model In this model of a food chain in the Florida Everglades, the algae make food using the sun’s energy. Algae are tiny living things that make their own food.

14. Modeling a Simple System A Model of a Simple System This model of an Everglades food web contains overlapping food chains.

15. Modeling a Complex System How Arctic Sea Ice Melts The Arctic sea-ice system can be modeled by a diagram. What is the input, process, and output in this model? http://studyjams.scholastic.com/studyjams/jams/science/scientific-inquiry/scientific-theory-and-evid.htm