CONTENTS Seeking scientific knowledge 4 The theory of light 6 A universal force 8 The origin of species 10 Germ theory of disease 12 Explaining radiation 14 Inheritance and genetics 16 Light space and time 18 An expanding universe 20 The start of the universe 22 The reshaping of Earth 24 The genetic code for life 26 The origin of cells 28 Glossary 30 Answers 31 Index 32
SEEKING SCIENTIFIC KNOWLEDGE Scientists seek knowledge about the world around us To do this they make careful observations which lead to new theories Scientists design experiments to test their theories Depending on the evidence of the experiments good theories are kept and bad ones are discarded 4 Scientists in ancient times Early scientists often worked in many different areas of knowledge One of the first scientists the ancient Greek Aristotle 384 322 bce wrote about physics biology astronomy and psychology Today scientists usually specialize in one field of study Building knowledge Scientists make new discoveries by building on the work of the scientists that came before them In this way our scientific knowledge grows When asked to describe his own discoveries in 1675 the famous English physicist Isaac Newton paid respect to other scientists by saying If I have seen further it is only by standing on the shoulders of giants
The scientific method The scientific method is a process that scientists follow in order to increase their understanding of a problem The scientific method usually consists of these steps 1 Ask a question 2 Carry out research by gathering information and making observations 3 Make a hypothesis which is a guess about what the answer might be 4 Design an experiment to test your hypothesis making a prediction of what will happen 5 Analyze your results and present your conclusion Using this method scientists are able to collect evidence that supports their theories They can also use the scientific method to show that a theory is wrong Scientists in the Islamic world were among the first to use the scientific method more than 1,000 years ago In the 800s Persian chemist Jabir ibn Hayyan was one of the first scientists to carry out experiments in a laboratory 5 Teamwork Scientists often work together in large teams At the European Organization for Nuclear Research CERN thousands of scientists carry out experiments using the Large Hadron Collider This machine smashes together tiny subatomic particles at close to the speed of light This recreates conditions from near the beginning of the universe to test theories about the structure of space Read on to discover the challenges that scientists have overcome through the ages The answers to each project's questions are found on page 31
