The Scientific Revolution In the mid-1500s, scientists begin to question accepted beliefs and make new theories based on experimentation. Scientists continued this revolutionary process into the 19 th, 20 th and 21 st centuries.

During the Middle Ages, Europeans’ understanding of the nature of the world around them was based on the writings of ancient classical philosophers such as Aristotle and Ptolemy. The Renaissance of the 15 th and 16 th centuries led scholars to examine these texts more closely. A new enthusiasm for knowledge, in addition to a greater belief in the abilities of humanity, led some to start making observations and formulating new theories.

Central to this new spirit of inquiry was an insistence that theories should be based on experimental evidence and not on the authority of ancient sources. The Scientific Revolution of the 16th and 17th centuries changed the way Europeans saw the world and promoted the application of scientific methods of rational inquiry to all aspects of life.

The Roots of Modern Science The Medieval View Most knowledge in Middle Ages comes from Bible and Greco-Roman sources Believed in the geocentric theory— moon, sun, planets revolve around earth

The Roots of Modern Science A New Way of Thinking Renaissance prompts new ways of thinking (1300–1600) Scientific Revolution—new way of viewing natural world— based on observation, inquiry New discoveries, overseas exploration open up thinking Scholars make new developments in astronomy, mathematics

A Revolutionary Model of the Universe The Heliocentric Theory Copernicus develops heliocentric theory—planets revolve around sun Later scientists mathematically prove Copernicus to be correct

1473–1543 Nicolaus Copernicus Polish priest and mathematician. He denies the medieval belief, inherited from the classical Greek astronomer Ptolemy (c. 90– 168), that the Earth is the center of the universe and develops the revolutionary theory that the Earth and planets revolve around the Sun (heliocentric theory) Heliocentric Model of the Solar System

Revolutionary Model of the Universe Galileo’s Discoveries Italian scientist Galileo Galilei makes key advances in astronomy -makes discovery about planet surfaces, supports heliocentric theory Conflict with the Church Church attacks Galileo’s work, fears it will weaken people’s faith Pope forces Galileo to declare his and other new findings are wrong

Galileo at trial before the Inquisition in Painting, 17th century.

1564–1642 Galileo Galilei, Italian mathematician and scientist. The first to use telescopes for astronomy. He describes the surface of the Moon and the rotation of the moons of Jupiter. Also establishes basic laws of motion from experimentation. He is arrested by the Inquisition and forced to recant his endorsement of the heliocentric Theory. Heliocentric Model of the Solar System

1571–1630 Johannes Kepler, German mathematician and astronomer. Accepts the heliocentric theory after examining data gathered by the Danish astronomer Tycho Brahe (1546–1601). He explains that the orbits of the planets are elliptical and not circular as Copernicus has suggested Heliocentric Model - Elliptical

The Scientific Method A Logical Approach Revolution in thinking leads to development of scientific method -series of steps for forming, testing scientific theories Bacon and Descartes Thinkers Bacon and Descartes help to create scientific method Bacon urges scientists to experiment before drawing conclusions Descartes advocates using logic, math to reason out basic truths

1561–1626 Francis Bacon, English philosopher. His Novum organum (1620) stresses the importance of proper scientific method: theories must be supported by proof acquired by experimentation and observation Scientific Method

1596–1650 René Descartes, French philosopher and mathematician. Develops analytic geometry and other mathematical techniques useful in theoretical science. He believes that mathematical proof is the model for rational scientific inquiry. His best-known philosophical work, Meditations on First Philosophy, emphasizes the importance of accepting only indubitable evidence Scientific Method

Newton Explains the Law of Gravity Newton’s Theories English scientist Isaac Newton develops theory of motion - states same forces rule motion of planets, matter in space, earth Motion in space, earth linked by the law of universal gravitation - holds that every object in universe attracts every other object Newton views universe as a vast, perfect mechanical clock

1642–1727 Issac Newton, English physicist and mathematician. One of the greatest theoretical scientists in history. He discovers the law of gravitation after studying Kepler’s laws of planetary motion and formulates three laws of motion that form the basis of physics until the 20th century Also invents the reflecting telescope (uses a curved mirror to focus light) Develops the mathematical system known as calculus. Gravity, Laws of Motion, Calculus

Scientific Instruments Scientists develop microscope, barometer, thermometer New instruments lead to better observations, new discoveries

1514–1564 Andreas Vesalius, Belgian physician and anatomist. He describes human anatomy more accurately than the ancient Greeks. His work brings a sentence of death from the Inquisition for immorality, but he is not executed Human Anatomy

Dura mater—the membrane surrounding brain. Anatomical drawing by Andreas Vesalius (1543).

1578–1657 William Harvey, English physician and anatomist. He discovers the circulation of the blood and describes the purpose of arteries, veins, and the heart. Human Anatomy – Circulatory System

Edward Jenner, English physician and scientist. Creates world’s first vaccination— for smallpox Medicine, Vaccination

1627–1691 Robert Boyle, Irish physicist and chemist. He investigates the properties of air and develops a theory describing the relationship between the pressure and volume of gases (known as Boyle’s Law). InThe Sceptical Chemist (1661) he questions the accepted belief that the world is made up of just four elements (Earth, Air, Fire, Water) and argues that they can be broken down into more fundamental, chemical elements Chemistry

The Scientific Revolution Continues Michael Faraday, (1791 – 1867) English scientist who contributed to the fields of electromagnetism and electrochemistry. Charles Robert Darwin (1809 – 1882) English naturalist best known for his contributions to evolutionary theory

Gregor Johann Mendel ( ) German scientist and Augustinian monk who gained posthumous fame as the founder of the modern science of genetics Sigmund Freud (1856 – 1939) Austrian neurologist who became known as the founding father of psychoanalysis

Louis Pasteur (1822 – 1895) French chemist and microbiologist Renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases, and his discoveries have saved countless lives ever since. Marie Curie (1867 – 1934) Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the first woman to win a Nobel Prize, the only woman to win in two fields, and the only person to win in multiple sciences.

Niels Henrik David Bohr (1885 – 1962) Danish physicist who made foundational contributions to understanding atomic structure and quantum theory Received the Nobel Prize in Physics in Albert Einstein (1879 – 1955) German-born theoretical physicist. He developed the general theory of relativity He is best known in popular culture for his formula E = mc2 He received the 1921 Nobel Prize in Physics

Enrico Fermi (1901 – 1954) Italian physicist best known for his work on the first nuclear reactor and for his contributions to the development of quantum theory, nuclear and particle physics and statistical mechanics. He is one of the men referred to as the "father of the atomic bomb". Awarded the 1938 Nobel Prize in Physics Werner Heisenberg (1901 – 1976) German physicist and one of the key creators of quantum mechanics. Awarded the Nobel Prize in Physics for 1932

Alexander Fleming, (1881 – 1955) Scottish biologist. His best-known discovery is the antibiotic substance penicillin from the mold in 1928, Won the Nobel Prize in Medicine in 1945 J Robert Oppenheimer (1904 – 1967) American physicist He is among the persons who are often called the "father of the atomic bomb" for their role in the Manhattan Project, the World War II project that developed the first nuclear weapons.

Gregory Pincus (1903 – 1967) American biologist who co-invented the birth control pill Jonas Salk (1914 – 1995) American medical researcher and virologist He discovered and developed the first successful inactivated polio vaccine.

James Watson (1928) and Francis Crick (1916–2004), discovered the structure of DNA, but only by drawing on the work of many scientists who came before them, including Rosalind Franklin.

Let’s see where these scientists rank on the 100 Most Influential Persons of the Millennium.