Concepts 4 Checked Slides PDF

# In what ways do all humans employ scientific thinking? - Scientific thinking is based on everyday ideas of observation and trial-and-error experiments. ## Example: Astronomical observations benefit ancient societies - Keeping track of time and seasons for practical purposes: - Agriculture...

# In what ways do all humans employ scientific thinking? - Scientific thinking is based on everyday ideas of observation and trial-and-error experiments. ## Example: Astronomical observations benefit ancient societies - Keeping track of time and seasons for practical purposes: - Agriculture - Religious and ceremonial purposes - Aid to navigation ## Ancient Greek Science - Modern science traces its roots to the Greeks - Islamic scientists preserved and extended Greek science ## Development of Astronomy - So far astronomy only involved making observations, recognizing basic patterns and making rudimentary predictions. - A crucial part of the scientific method - building models/hypotheses that did not resort to supernatural or godly influence was missing. - This was about to change in Greece.... ## Greek Astronomy ### Eratosthenes Measures the Earth *c. 240 BC* - **Measurements:** - At noon on the first day of summer, - Syene: sun directly overhead - Alexandria: sun at 7 degrees from vertical - Syene to Alexandria distance 5000 stadia - **Angle = 7 degrees** - **Calculate circumference of Earth:** - 7/360 x (circum. Earth) = 5000 stadia - ➡circum. Earth = 5000x360/7 stadia ≈ 250,000 stadia - **Compare to modern value (~40,100 km):** - Greek stadium ≈ 1/6 km - 250,000 stadia ≈ 42,000 km ## Greek Astronomy - 500BC: Pythagoras suggests that the Earth is a sphere and not flat, as had been previously assumed - What observations of the ancient Greek astronomers could you use to prove the spherical model of the earth to a member of the Flat Earth Society. ## Greek Astronomy - **Earth as a sphere** - Ships disappear sailing away from shore by sinking below horizon with mast last visible; Earth's curvature visible over 13 mile distance. - Circular shadow projected by Earth when it eclipses the Moon. - When traveling north, new stars appeared above northern horizon, while stars previously seen along southern horizon no longer visible; reverse true traveling south. ## How did the Greeks explain planetary motion? - Heavens must be “perfect” objects moving on perfect spheres or in perfect circles. - But this made it difficult to explain apparent retrograde motion of planets... ## Greek Astronomy - The modern heliocentric model easily explains apparent retrograde motion of planets. - The most sophisticated geocentric model was that of Ptolemy (A.D. 100-170) - the Ptolemaic model: - Sufficiently accurate to remain in use for 1,500 years. - Ptolemy's model could handle retrograde motion ## The Ordered Universe - **Physical events:** - Predictable - Quantifiable - Without the predictability of physical events the scientific method could not proceed ## The Ordered Universe - **Experimentation** - collecting data using instruments and mathematical calculations ## The Nature of Science - How can we distinguish science from non-science? - Defining science can be surprisingly difficult. - Science from the Latin _scientia_, meaning "knowledge." - But not all knowledge comes from science... ## The Scientific Method - This "process" - never truly finished - Over time - hypothesis receives more support - Testing continues: - Making predictions - Observing results ## The Scientific Method - a "process" - Identifying patterns - Hypothesis - Prediction - Experimentation (Observation) - Identifying patterns ... ## The Idealized Scientific Method - Based on proposing and testing hypotheses - Hypothesis = educated guess ## But science rarely proceeds in this idealized way - Sometimes we start by "just looking" then coming up with possible explanations. - Sometimes we follow our intuition rather than a particular line of evidence. ## Hallmarks of Science: #1 - Modern science seeks explanations for observed phenomena that rely solely on natural causes. ## Hallmarks of Science: #2 - Science progresses through the creation and testing of models of nature that explain the observations as simply as possible. ## Hallmarks of Science: #3 - A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations. ## What is a scientific theory? - The word theory has a different meaning in science than in everyday life. - In science, a theory is NOT the same as a hypothesis, rather: - **A scientific theory must:** - Explain a wide variety of observations with a few simple principles, __AND__ - Must be supported by a large, compelling body of evidence. - Must NOT have failed any crucial test of its validity. ## Thought Question - **Darwin’s theory of evolution meets all the criteria of a scientific theory. This means:** - A. Scientific opinion is about evenly split as to whether evolution really happened. - B. Scientific opinion runs about 90% in favor of the theory of evolution and about 10% opposed. - C. After more than 100 years of putting Darwin's theory to the test, the theory stands stronger than ever, having successfully met every scientific challenge to its validity. - D. There is no longer any doubt that the theory of evolution is absolutely true. - **Darwin's theory of evolution meets all the criteria of a scientific theory. This means:** - A. Scientific opinion is about evenly split as to whether evolution really happened. - B. Scientific opinion runs about 90% in favor of the theory of evolution and about 10% opposed. - C. After more than 100 years of putting Darwin's theory to the test, the theory stands stronger than ever, having successfully met every scientific challenge to its validity. - D. There is no longer any doubt that the theory of evolution is absolutely true.