Outline the historical development of
models of the universe from the time of
Aristotle to the time of Newton……
By Rebecca Smith
Scientific Background
•Astronomy is the oldest science about 1000 BC.
•Used by Priests and Holy Men for planting cycles and
organisation of religious celebrations
•First models developed with NO Formulas NO technology and
a lot of uncertainty
Timeline of major models…
Aristarchus
(312 –
230BC)
Aristotle
(384-322 BC)
Nicholas
Copernicus
(1473-1542)
Claudius
Ptolemy (AD
150)
Johannes
Kepler
(1571-1630)
Tycho Brahe
(1546 –
1601)
Isaac Newton
(1643-1727)
Galileo
Galilei
(1542 –
1643)
Definitions
• Geocentric – universe where the Earth is placed at the centre
• Heliocentric – universe where the sun is placed at the centre.
• Parallax effect - a change in displacement of an object taken from two
different frames of reference and can be measured by the angle of inclination of the two
lines.
OVERVIEW OF ARGUMENTS
FOR • incorporation of heaven (Christians)
• Consistent with other models
• Easy to understand
• Ease for measurements
AGAINST • Too complex
• Too simplistic
• No mathematical evidence
• Summary
• Consistent with other models
• Only relative measures made
• Religious views
ARISTOTLE
•FEATURES :
• Main
•Earth to be flat, spherical universe with
heavens above.
•Geocentric model
Aristarchus
FEATURES :
•
•
•ARGUMENTS :
•gaining Christian approval due to incorporation
of heavens
•becoming to complex with additions and many
modifications and having no real impact on
scientific advances
•in astronomy but rather acted more as a
summary.
•Unfathomable nature of infinity
•could not detect a parallax effect, and could not
explain universal changes.
First heliocentric model
Developed idea that earth
rotated on axis once a day
giving illusions of astronomical
features.
ARGUMENTS :
•
Disliked due to so different from
widely accepted Aristotle.
Claudius Ptolemy
FEATURES :
•
•
Compiled an extensive summary of all the Greek's previous
studies on astronomical physics.
This model reliably predicted positions of planets, was
geocentric, showed the earth to be at rest and explained the
motion of planets as the combination of perfect circles.
ARGUMENTS :
•
•
The model was advantageous as it provided useful predictions
to both past and present planetary positions and allowed was
consistent with previous models, however the model had no
mathematical evidence,
was very complex and measures were found to be relative not
absolute.
RECOMMENDATIONS :
Whilst the Ptolemy model can not be used to make accurate mathematical
calculations about the universe, it is a very effective model in providing a
summary of all previous astronomical theories, and assists one in learning about
the history of models of the universe.
Nicholas Copernicus
FEATURES :
•
supported the Aristarchus heliocentric model, where the
stationary sun was in the centre of the model with
everything else in the universe revolving around it.
ARGUMENTS :
•
•
•
•
ease for mathematical calculations
simpler model.
church and government had the major objections to this
model as there was no account for the heavens unlike the
Aristotle model.
The inadequacies of the model. As only a change of
reference was shown
RECOMMENDATIONS :
Copernicus` model is essential in the study of the history of models of the
universe. Whilst it was criticised for only being a change in the frame of
reference, this change makes this model one of the most accurate first
models ever developed. This model is definitely recommended as an
important discovery.
FEATURES :
Tycho Brahe
•
•
•
Johannes Kepler
studied and plotted the night sky in extensive detail, this
was seen as an incredible achievement as he managed
to do this with no aid of a telescope.
combination of both geocentric and heliocentric models
Due to lack of technology, Brahe could not show a
parallax effect,
FEATURES :
•Tycho Brahe` talented mathematician assistant,
•developed mathematical laws to determine the movemen
planets.
•He discovered; that planets moved in ellipses, known as t
Law of ellipses and the Law of Periods.
ARGUMENTS :
Due to Kepler being a protestant in Austria, his theory was
able to be voiced openly with little risk, Rome's arguments
however were still the same as they were with the Coperni
model.
Galileo Galilei
FEATURES :
•
•
•
believed in the Copernicus model.
Galilei was a brave man who made his own telescope and became the first person to point one at
the night sky.
he disproved Ptolemy's geocentric model.
ARGUMENTS :
•
Roman Church views
Galilei left a great legacy even though he had to fight many arguments as a
result of his findings.
Isaac Newton
FEATURES :
•
•
•
•
The physics that the great Isaac Newton (1643 – 1727) brought to the world of Astronomy allowed the proof of a
heliocentric model.
summarising a long history of developments.
Newton's major law which aided this include the Law of Universal Gravity, which describes gravity as a force which
exists between two masses, with particular effect on large masses such as planets.
From this law Kepler's laws could be derived and therefore the explanation for why planets orbit in ellipses not circles
was found. This supported a parallax effect and allowed the heliocentric model to be supported.
Recommendation
When recommending the best astronomical model of the universe it is difficult to
choose which model is the most efficient. Newton`s model can be suggested
as the best as there is mathematical evidence and workings that prove aspects of
the universe. However his model could only be produced with the strong foundation
of models previously developed. Therefore when studying the universe, Newton’s
model is most efficient however all models specifically Ptolemy's and Copernicus`
(mentioned previously) are found to be productive in providing information on the
development of models of the universe.