Ms. JohnsonFoundations

CHAPTER 17: SCIENTIFIC DISCOVERY

Science is the search for the truth about the universe. The processes of science include questioning, exploring, experimenting, observing, measuring, concluding, and communicating. Science also includes a body of knowledge consisting of facts, theories, principles, laws, and so on.

The scientifi c method is a procedure by which scientifi c discovery can be accomplished. However, scientifi c discovery is not a single process; it can be accomplished in many diff erent ways.

Factors that infl uence scientifi c discovery may be social, economical, and technological.

The ways scientifi c discovery occurs vary greatly in time and the number of scientists contributing to the discovery. It often takes many years and many individuals to arrive at the truth about some aspect of the universe.

OBJECTIVES

ScienceScientific methodHypothesisTheory

VOCABULARY

Science: the search for the truth about the universe and a body of knowledge consisting of facts, laws, principles, and theories. It is a process by which information about the

universe is gathered and organized into bodies of knowledge such as biology, physics, chemistry, geology, and astronomy.

Science seeks answers about the world around us.

Science also involves exploring, experimenting, observing, measuring, concluding, and communicating.

SCIENCE DEFINED

Scientific method: a process that helps scientists make discoveries.State the problemCollect informationForm a hypothesisTest your hypothesis (experiment)Record observationsCheck results (or re-test)

If the results are incorrect, form a new hypothesis and test it

Draw conclusionsCommunicate results

SCIENTIFIC METHOD

Hypothesis: plausible guess based on the known facts Proposed to answer the questions Followed by experimentation to test the hypothesis

If all evidence gathered supports the hypothesis and appears to lead to new truths about the universe, a theory can be presented.

A theory can raise new questions that will lead to new hypotheses, new experiments, and new studies.

SCIENTIFIC METHOD

A scientific experiment includes a control group and an experimental group. Control: conditions

remain the same or as close to normal so the experimental group can be compared to it

Experimental: the group that is manipulated in an experiment

SCIENTIFIC METHOD

Many of the great discoveries in science have come about over a span of many years, with contributions made by many people.1. Plate Tectonics2. Heliocentric Solar System3. Germ Theory4. Atomic Theory

EXAMPLES OF MAJOR SCIENTIFIC DISCOVERIES

Two discovery questions: How did the

continents get to their present shapes and positions?

What process could cause the continents to shift on Earth’s surface?

1912 Alfred Wegener proposed

continents were moving due to the shapes of the continents and matching features of rocks and fossils had on both sides of the Atlantic

Wegener thought the continents were once one large landmass

1912-1960 Eventually interest

decreased because no one could come up with an idea for how the continents moved

Wegener’s theory lacked an answer to this, even with the evidence he found

PLATE TECTONICS

1960 Oceanographers

discovered the Mid-Atlantic Ridge that ran North and South down the Atlantic Harry Hess believed

that new rock material was being pushed up and outward in opposite directions- Seafloor Spreading

1969 Fred Vine and Drummond

Matthews found matching magnetic polarity on both sides of the Ridge to support Hess’ ideas

Sea Floor Spreading was the suffi cient evidence needed to support the theory of continental drift

1970s Detailed maps of the

ocean floor revealed all the features of seafloor spreading

PLATE TECTONICS

Wegener is credited with the theory of continental drift even though other scientists helped support the evidence he had

Many scientists were skeptical about the theoryToday, with technology so advanced, continental drift

has been tested thoroughly and is accepted by almost all scientists.

PLATE TECTONICS

Question: What is Earth’s position in the solar system and in the universe?

6 th Century B.C. Early Greeks believed the sun

was the center of the universe, but lacked any evidence to support it

About 350 B.C. Aristotle’s geocentric model

(Everything revolved around the Earth)

About 150 A.D. Ptolemy backed up Aristotle

with his idea of retrograde motion. His explanation was incorrect but was accepted because he had data and it upheld the idea of an earth-centered universe.

HELIOCENTRIC SOLAR SYSTEM

1543 Copernicus proposed heliocentric (sun-centered) theory based on

his observations of the movement of the stars and planets (claimed they were perfect circles around the sun).

1632 Galileo supported the heliocentric model. With a telescope he observed the phases of Venus; he saw that

Venus sometimes passed the earth and sun, so he assumed it was going all the way around the sun.

1618 Kepler observed Mars and derived mathematical laws of planetary

motion- determined the orbit was elliptical (oval) and not circular. 1784

Herschel concluded that our solar system was a part of a large cluster of stars he called The Milky Way. He saw less stars out from the sun and concluded the sun was the center of the galaxy. He was later proved wrong about the location of the sun but his idea of The Milky Way was correct.

HELIOCENTRIC SOLAR SYSTEM

It took about 2500 years for scientists to understand Earth’s place in the universe. Each one provided information to either change or refine

evidenceToday, scientists are still gathering new evidence

using the Hubble Telescope to further refine the original question.

HELIOCENTRIC SOLAR SYSTEM

Question: What causes diseases?

1800 Ben Rush, a doctor of his time,

believe that imbalance of body fluids caused sickness and thought the best way to cure them was through bleeding, blistering, and vomiting- which were supposed to restore the balance.

1820-1900 People were wary of doctors

and medicine became replaced by trickery. Causes of diseases were not wanted.

Less scientific approaches were used to try to cure sicknesses

Such as hydrotherapy, electrical treatment, and “cure all” medical potions

GERM THEORY

1840s-1870s Scientists found that

increased cleanliness and use of purified water were decreasing the number of childbed fever and cholera cases.

1860s Civil War casualties

forced the medicine field to study the causes of disease and infection in more detail.

1870 Louis Pasteur

developed the Germ Theory of disease- stated that microorganisms were the cause of some diseases.

GERM THEORY

Scientific medical treatment of disease was accepted slowly because people did not trust doctors

Many of the nonscientific methods of treating disease were harmful to patients

GERM THEORY

Question: What is the structure of the atom?

The structure of the atom was not always known even though it was known to be the smallest particle of an element.

ATOMIC THEORY

Early 1800s John Dalton stated that all matter is composed of atoms; he

believed that all atoms were similar in structure but that each element has its own atoms and those atoms could be combined to form compounds.

1897 Joseph J. Thompson discovered electrons, the negatively

charged particles in atoms.1903

Philip Lenard proposed that atoms were mainly empty space, not solid spheres.

1911 Ernest Rutherford concluded that atoms consist of a

massive central nucleus surrounded by space and electrons.1913

Niels Bohr suggested electrons travel in circles around the nucleus.

ATOMIC THEORY

Scientific discoveries are at an ever-increase rate.

Each new discovery leads to more questions and eventually to more research in an effort to answer these questions.

The advancement of scientific discovery can be attributed to an increase in technology.

SCIENTIFIC DISCOVERY

Chapter 17QUESTIONS?