 “Science may be described as the art of systematic oversimplification.” --Karl Popper ( )  “Science is a way of thinking more than it is a body of knowledge.” --Carl Sagan ( )

1. Observartion 2. Hypothesis 3. Experiment 4. Law 5. Theory

1. Observe and record data 2. Classify relevant data 3. Search for a pattern in the data 4. Formulate a hypothesis 5. Make a predication based on steps Test prediction using an experiment 7. If experiment confirms hypothesis = discovery of a scientific law Controllability: vary only 1 factor at a time to help isolate cause of phenomenon being investigated Measurability: relevant variables must be measurable, which allows precisions & objectivity Repeatability: others must be able to repeat experiment & confirm results 8. Develop a theory, which explains & unifies various laws based on an underlying principle: a good theory explains why laws are the way they are & provides focus for further research* * Lagemaat, Richard van de, Theory of Knowlesde: for the IB Diploma, Cambridge: Cambridge University Press, 2009, p.226.

Observation:  Observation of the nighttime sky over the centuries became better, leading to a more complicated picture of heavenly bodies  Ptolemy’s geocentric model of the universe become less orderly and more messy, needing more & more new explanations to make sense of the model

Hypothesis  Nicolaus Copernicus ( ) proposes a heliocentric model of the universe with the sun at the center & the Earth revolving around the sun  Simpler & more elegant explanation

Prediction  In Ptolemaic model, Venus always same size  In Copernican model, Venus’ size should vary depending on its distance from the Earth  1609: Galileo ( ) uses his telescope to observe that Venus’ size does vary depending on its relative position from Earth just as Copernicus had predicted

Law  Johann Kepler ( ) used the above observations & discoveries in his study of the heavenly bodies  Kepler developed his laws of planetary motion, which included his assertion than planets revolve around the Sun in ellipses

Theory  Isaac Newton ( ) devised the theory of gravity  Theory of Gravity: there is a force of attraction between objects, directly proportional to their masses & inversely proportional to the square of the distance between objects (2x distance: ¼ gravitational attraction)  Broader theory of gravity explained why apples fall (probably apocryphal story), people have weight, movement of the tides & led to discovery of Uranus (1781) & Neptune (1846)

 Scientific progress needs a background of careful observation (Kepler need Tycho Brahe, )  Technology can strengthen powers of observation (telescope & microscope)  Imagination has an important role in scientific discoveries (Copernicus saw what so many others had not seen*)  Mathematics plays a key function; it gives expression & precision (Newton’s laws) *Aristarchus (3 rd century BCE Greek astronomer proposed a heliocentric universe)

Observation  Relevance: humans always begin with an idea(s) of what is or is not relevant to a problem  Selective nature of perception: possible to overlook or not anticipate something that turns out to be relevant (# people in a room during an experiment)  Expectations can influence observations  Expert seeing: practice & experience to look in microscope or read an ultrasound  Observer effect: an of observation can affect what is observed (thermometer)

Hypothesis  Confirmation bias: accept evidence that confirms biases & reject evidence that does not  Charles Darwin ( ): “’I followed a golden rule, namely that whenever a new observation or thought came across me, which was opposed to my general results, I make a memorandum of it without fail at once; for I had found by experience that such facts and thoughts were far more apt to escape from the memory than favorable ones.” (Lagermaat, p. 230)

Hypothesis  Background assumptions: humans make assumptions that may prove to be incorrect (notion that stars were close to the Earth)  Different hypotheses can be consistent with a set of data  Principle of Simplicity: in the presence of two or more competing theories that make the same predictions… the simpler theory is to be preferred

Law  Problem of Induction: move from observed to unobserved (all swans are white or all metals expand when heated)  Practical Problems: how many observations are needed?  Theoretical Problems:  science is based on empricism (no claims beyond the observed)  grounding in observation gives authority to science not found in pseudo- science  do we refuse to make claims that go beyond what has been observed?  how do new laws & discoveries get made  allow right of scientists to reason from particular to general  abandon claim that science is strictly emprical?