The Nature of Science

1. The Nature of Science

2. Questions for Consideration • How do scientists solve problems? • What are some aspects of a scientific experiment? • What is the difference between a scientific law, a hypothesis, and a theory? • What is the importance of scientific literacy?

3. How Do Scientists Solve Problems? • The myth of “the scientific method”. • Not just one method for problem-solving. • “Scientific method” often taught in school is a simplified procedure for building knowledge. • Real science can be much more exciting and complex. • No specified order for building knowledge.

4. How Do Scientists Solve Problems? • Online Homework Assignment: • Visit the following site: • http://www.undsci.berkeley.edu • Answer the questions on the worksheet you have been given. • Due Friday, January 30, 2009. • For a copy of the worksheet, click below:

5. What Are Some Aspects of a Scientific Experiment? • Variables – factors that can change. • Manipulated variable – changed by the experimenter. • “Independent variable” • Responding variable – observed by the experimenter. • “Dependent variable” • Control • Variables that are kept constant. • Ensures that the impact of another factor can be better understood.

6. Example • A contract research organization (CRO) is being paid to find out if a new drug for tuberculosis yields better results than the standard treatment. • They organize a double-blind study: • One group of patients is given the new drug. • One group of patients is given a placebo. • Placebo: A “sham” therapy that does not actually contain any sort of medication. • Both groups’ progress is compared to the progress of patients who receive the standard therapy.

7. Example • In the clinical study, what is the CRO attempting to find out? • If the new TB drug is more effective than the standard treatment. • What is the control group? • The placebo group is the control group. • What is the responding variable? • The health of the group that receives the drug (compared to the health of the group that receives the standard treatment).

8. Fact, Hypothesis, Law, Theory • Fact • An observation. • Hypothesis • A proposed explanation for observations. • Can be supported or refuted by further testing. • Law • A concise statement that describes a relationship in nature. • Theory • A broadly supported explanation for a set of observed phenomena. • Theories CANNOT be 100% proven. • They are generally accepted as true unless disproven.

9. The Nature of Science • Science: • is tentative. • doe NOT follow a single method. • is goal-oriented. • uses laws to describe and theories to explain. • is creative.

10. The Tunguska Event • On June 30, 1908 there was a large explosion above the Tunguska region in Russia. • At about 7:17 am local time, eyewitnesses near Lake Baikal in Russia reported seeing a column of intense blue light moving across the sky. • A few minutes later, they saw a bright flash of light and heard loud bangs, like artillery fire.

11. The Tunguska Event • Witnesses closer to the explosion were knocked off their feet by the shockwave. • They reported intense heat and pressure from the blast. • Windows were broken hundreds of kilometers from the blast site. • Tremors from the explosion were registered at seismic stations all across Europe and Asia. • The explosion is thought to have been equivalent to 10 – 15 Megatons of TNT, or about 1000 Hiroshima A-bombs. • It is also thought that the explosion happened about 5 – 10 kilometers above the Earth’s surface.

12. The Tunguska Event

13. The Tunguska Event • What caused the Tunguska event? • There have been many proposed explanations, or hypotheses: • An alien spaceship exploded high above the Earth. • A small black hole hit the Earth. • An asteroid or comet entered Earth’s atmosphere and exploded. • A top-secret superweapon was being tested or deployed by the US or Russia. • A chunk of antimatter entered Earth’s atmosphere and self-destructed when it contacted normal matter. • A huge amount of natural gas was released from the Earth’s crust and exploded in the air.

14. The Tunguska Event • Scientists actively debate various hypotheses and attempt to use available evidence to develop a theory. • The current theory: a comet or asteroid exploded in the lower atmosphere. • Supporting evidence: • Asteroids and comets do exist. • Particles from outer space enter Earth’s atmosphere every day. • When they do, they burn up or explode because of the heat generated by the compressed air in front of them.

15. The Tunguska Event • Supporting evidence: • A larger object (a few tens of meters across) would release energy consistent with the Tunguska blast. • Fragments found embedded in downed trees are consistent with asteroid and comet composition. • Eyewitness reports are consistent with an asteroid or comet impact. • Also, the asteroid/comet impact hypothesis is parsimonius. • it doesn’t require the existence of things that must be assumed without evidence, like alien spaceships or secret superweapons.

16. The Importance of Scientific Literacy • You are going to see ten true-false statements that will test your scientific literacy. • Try to determine whether each statement is true or false.

17. The Statements TRUE • 1. Science only produces tentative conclusions that can change. • 2. Science has one uniform way of conducting research called “the scientific method”. • 3. When being scientific one can have faith only in what is justified by empirical evidence. • 4. To be scientific one must conduct experiments. • 5. An experiment can prove a theory true. • 6. Scientific theories are just ideas about how something works. • 7. An accepted scientific theory is a hypothesis that has been confirmed by considerable evidence and has endured all attempts to disprove it. • 8. Scientists construct theories to guide further research. • 9. Scientists work alone without sharing data or ideas. • 10. Imagination and creativity are used in all stages of scientific investigations. False TRUE false false false TRUE TRUE false TRUE

18. What Is The Importance of Scientific Literacy? • Scientific literacy makes you an informed person: • It helps you make decisions in elections. • It keeps you from being fooled by people who make fraudulent claims. • It keeps you from being worried about things you don’t really have to worry about.

19. What Is The Importance of Scientific Literacy? • If somebody tells you that the world is going to end in 2012, be skeptical. • If somebody tells you that vaccines cause autism in children, ask for evidence. • If somebody tells you that the Large Hadron Collider will destroy the world, consult a real scientist to find out. • Examine the evidence for yourself and make your own informed decisions.

20. Skepticism The truth is out there...but so is this garbage.