The Scientific Method. Activity: Kepler’s 1 st law Form a group of 3-4 people Pick up a rope Construct ellipses by walking around Questions: –What happens.

The Scientific Method

Activity: Kepler’s 1st law

• Form a group of 3-4 people• Pick up a rope• Construct ellipses by walking

around• Questions:

– What happens if you make the rope loop longer/shorter? In Nature?

– What happens if the “Focal people” change position? In Nature?

Activity: Kepler’s 2nd law

• Get out your worksheet books• Form a group of 3-4 people• Work on the questions on the sheet• Fill out the sheet and put your name on top• Hold on to the sheet until we’ve talked about

the correct answers• Hand in a sheet with the group member’s

names at the end of the lecture • I’ll come around to help out !

Activity: Kepler’s 3rd law

• Get out your worksheet books• Form a group of 3-4 people• Work on the questions on the sheet• Fill out the sheet and put your name on top• Hold on to the sheet until we’ve talked about

the correct answers• Hand in a sheet with the group member’s

names at the end of the lecture • I’ll come around to help out !

The Scientific Method• Systematized by Francis

Bacon, Descartes and Galileo in the 17th century

• Not the only way of knowing, but a very successful one

• A method to yield conclusions that are independent of the individual

• Conclusions are based on observation

Francis Bacon (1561-1626)

Contemporary of Shakespeare,

Elizabeth I, Kepler and Galilei

Rejects Aristotelianism and Scholasticism

Major Work:• Novum Organum (1620) (“New Tools”, the old Organum was Aristotle’s)

Francis Bacon (1561-1626)

Novum Organum Title:

Allegory on the daring mind: A Ship passes

through the “pillars of

Hercules”, beyond old

knowledge.

Rene Descartes – The RationalistDescribed the method to do science,

known for his mind-body dualism

Major Works:• Discourse (1637) [full title: Discours

de la méthode pour bien conduire sa raison et chercher la vérité dans les sciences]

• Meditations on first Philosophy (1641) [6 Meditations: Of the Things that we may doubt;

Of the Nature of the Human Mind; Of God: that He exists; Of Truth and Error; Of the Essence of Material Things; Of the Existence of Material Things; Of the Real Distinction between the Mind and the Body of Man]

Rene Descartes (1596-1650)

Rene Descartes’ Discourse

Describes the method to do science in a straightforward way (see below)

Major points:

• Science must be based on correct reasoning (logic)

• Science must be formulated in mathematical language

Starting line: “Good sense is the most evenly distributed thing in the world, for all people suppose themselves so well provided with it that even those who are the most difficult to satisfy

in every other respect never seem to desire more than they have.”

Modifying our Epicycle Model• More observation & reasoning shows that Mars

does not just go around an epicycle in 6 months

• Also: loop generated by epicycle is not the same as the size of the epicycle itself, see animation

• Modify model to better describe Nature: Epicycle turns once in a synodic period, i.e. time from one retrograde loop to the next

• See video

A Classical Example

• Aristotle observes that during lunar eclipses the Earth’s shadow on the moon is curved

• He assumes it will be curved for all eclipses• A hypothesis that explains this: the earth is round• A prediction of this theory is that the location of the

stars in the sky should be different for observers at different latitudes

• This is confirmed by additional observations– E.g. Canopus is visible in Egypt but not further north

• It is applied by Eratosthenes to determine the size of Earth

Scientific Literacy

• An important skill to have in an increasingly complex society

• As a voting citizen you should know what you are voting on

• As a consumer you should know (or be able to figure out) what you buy

• Makes life more interesting• Nobody knows everything, but smart people can

figure out fast if something is obviously wrong

What does this Juice contain?a) 100% Ruby Red Grapefruit Juiceb) A mix of juices, and nothing but juicesc) No Sugard) None of the above

“100% Juice”

…is the name of this juice that contains:

• Filtered water• Apple juice• White grape juice• Sugar (that is in

the juices)• Color, etc.