Science develops through objective analysis, instead of through personal belief. Knowledge gained in science accumulates as time goes by, building on work performed earlier. Some of this knowledge-such as our understanding of numbers-stretches back' to the time of ancient civilizations, when scientific thought first began. Other scientific knowledge such as our understanding of genes that cause cancer or of quarks (the smallest known building block of matter) -dates back less than 50 years. However, in all fields of science, old or new, researchers use the same systematic approach, known as the scientific method, to add to what is known.
41__________. For example, in 1676, the English physicist Robert Hooke discovered that elastic objects, such as metal springs, stretch in proportion to the force that acts on them. Despite all the advances that have been made in physics since 1676, this simple law Still holds true.
42__________. Sometimes scientific predictions go much further by describing objects or events that are not yet known. An outstanding instance occurred in 1869, when the Russian chemist Dmitry Mendeleyev drew up a periodic table of the elements arranged to illustrate patterns of recurring chemical and physical properties.
43__________. At the time, most geologists discounted Wegener's ideas, because the Earth's crust seemed to be fixed. But following the discovery of plate tectonics in the 1960s, in which scientists found that the Earth's crust is actually made of moving plates, continental drift became an important part of geology.
Through advances like these, scientific knowledge is constantly added to and refined. As a result, science gives us an ever more detailed insight into the way the world around us works.
44__________. However, with the dawn of the Industrial Revolution in the 18th century, this rapidly changed. Today, science has a profound effect on the way we live, largely through technology--the use. of scientific knowledge for practical
45__________. The refrigerator, for example, owes its existence to a discovery that liquids take in energy when they evaporate, a phenomenon known as latent heat.
A. Scientists utilize existing knowledge in new scientific investigations to predict how things will behave. For example, a scientist who knows the exact dimensions of a lens can predict how the lens will focus a beam of light. In the same way, by knowing the exact makeup and properties of two chemicals, a researcher can predict what will happen when they combine.
B. For a large part of recorded history, science had little bearing on people's everyday lives. Scientific knowledge was gathered for it sown sake, and it had few practical applications.
C. During scientific investigations, scientists put together and compare new discoveries and existing knowledge. In most cases, new discoveries extend what is currently accepted, providing further evidence that existing ideas are correct.
D. Tile principle of latent heat was first exploited in a practical way in 1876, and the refrigerator has played a major role in maintaining public health ever since. Tile first automobile, dating from the 1880s, made use of many advances in physics and engineering, including reliable ways of generating high-voltage sparks, while the first computers emerged in the 1940s from simultaneous advances in electronics and mathematics.
E. Some forms of technology have become so well established that it is easy to forget the great scientific achievements that they represent.
F. In science, important advances can also be made when current ideas are shown to be wrong. A classic case of this occurred early in the 20th century, when the German geologist Alfred Wegener suggested that the continents were at one time connected, a theory known as continental drift.
G. Other fields of science also play an important role in the things we use or consume every day. Research in food technology has created new ways of preserving and flavoring what we eat.