The Evolution of Astronomy and Science: From Ancient Observations to Modern Discoveries - , Study notes of Physics

Download The Evolution of Astronomy and Science: From Ancient Observations to Modern Discoveries - and more Study notes Physics in PDF only on Docsity!  The Night Sky o Ancient observers of the sky were perhaps the first humans to accept the most basic tenet of science. o Physical events are quantifiable and therefore predictable.  Stonehenge o Prehistoric stone monument on Salisbury Plain in southern England. o Structure consists of a large circular bank of earth surrounding a ring of single upright stones which in turn encircle a horseshoe shaped structure of five giant stone archways. o Without a written language, people would have to pass complex information about the movements of the Sun, the Moon, and the planets from one generation to the next.  Science by Numbers o Ancient Astronauts o Ockham’s razor, after William of Ockham a fourteenth-century English philosopher who argued that “postulates must not be multiplied without necessity” that is, given a choice, the simplest solution to a problem is most likely to be right. Scientists thus reject the notion of ancient astronauts building Stonehenge, and they relegate such speculation to the realm of pseudoscience.  Science in the Making o The Discovery of the Spread of Disease  During the 19th century, for example, Europe experienced an epidemic of cholera, a severe and often fatal intestinal disease.  The name of the disease is derived from the early days of medicine when “choler” was seen as one of the “humors” that governed human health. But even without knowing the cause of the disease physicians and scientists could observe the places and times when it occurred. o John Snow (1823-1858): Well-known London physician. Remembered in medicine as one of the pioneers in the new field of anesthesiology. Even attended the birth of Queen Victoria’s last children, administering chloroform during labor. o 1854- Snow makes a dramatic discovery. He noticed that the incidence of cholera that year seemed to be concentrated around a place called Golden Square a poor neighborhood where people drew their water from a place called the Broad Street pump. Snow found that the square was surrounded by a large number of homes where human waste was dumped into backyard pits. Argued that these findings suggested the disease was somehow related to contamination of the water supply. o Thus Snow’s discovery of a regularity in nature (between disease and polluted water) was the foundation on which modern sanitation and public health systems are based. o Robert Koch – 1890’s found that the disease was caused by a particular bacterium, Vibrio cholera, that is carried in human waste  Birth of Modern Astronomy o Claudius Ptolemy and Egyptian born Greek astronomer and geographer who lived in Alexandria in the second century AD- proposed the first widely accepted explanation for complex celestial motions. Working with the accumulation observations of earlier Babylonian and Greek astronomers, he put together a singularly successful model- a theory, to use the modern term, about how the heavens had to be arranged to produce the display we see every night.  The Historical Background: Ptolemy and Copernicus o Copernicus was a Polish cleric (1473-1543) considered a competing hypothesis that was to herald the end of Ptolemy’s crystal spheres. o Retained notions of a spherical universe with circular orbits, and even kept the ideas of spheres rolling within a sphere.  Observations: Tycho Brahe and Johannes Kepler o Ptolemaic placed Earth at the center and assumed that all orbits are circular o Copernicus placed the Sun at the center and assumed that all orbits are circular  Tycho Brahe showed the way out of this passé. Tycho observed and described a new star in the sky (a supernova). This discovery challenged the prevailing wisdom that the heavens are unchanging o Built his career on the design and use of vastly improved observational instruments. o Died and passed data to Kepler who made first law stating that all planets, including Earth, orbit the sun in elliptical not circular paths.  Birth of Mechanics o Mechanics is an old word for the branch of science that deals with the motions of material objects. o Galileo Galilei  Forerunner of the modern scientist. Famous for being first person to record observations of the heavens with a telescope which he built after hearing of the instrument from others.  Science of mechanics- the way things move near Earth’s surface.  Astronomical writings which supported the sun centered Copernican model of the universe led to his trial conviction and eventual house arrest by the Inquisition.  Science in the Making o Speed, Velocity, and Acceleration o Speed is the distance an object travels divided by the time it takes to travel the distance. o Velocity has the same numerical value as speed, but it is a quantity that also includes information on the direction of travel. o Acceleration is the measure of the rate of change of velocity. Whenever an object changes speed or direction, it accelerates. Acceleration is the amount of change in velocity divided by the time it takes change to occur. o Motion at a constant speed in a single direction is called uniform motion. o G=0.8m/s^2 o V=a x t