history of astronomy (timeline)

7/28/2019 History of astronomy (timeline)

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BIG BANG THEORY


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Georges Lemaitre, a Belgian astrophysicist and

Catholic priest, came to be known as the

"Father of the Big Bang".

Lemaitre proposed that the universe began as:

a single primordial atom of energy

something hot and dense that exploded

causing space to expand outward.


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In the late 1940s, George Gamow, a Russian-

American physicist, conceived of the Big

Bang theory as we know it today.

He and his colleagues proposed that if a big

bang had occurred, it would have left an

afterglow, traces of background radiation thatwould still be present


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In 1965, physicists Arno Penzias and RobertWilson started to search for faint radio signals(actually microwaves) from the outskirts of theMilky Way Galaxy.

While conducting their investigations, theyactually found the afterglow predicted byGamow.

It was important evidence that the universebegan with a hot big bang.

More recently, NASA's COBE satellite measuredthis radiation in great detail.

All of the measurements were consistent with theBig Bang theory.


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In 1979, particle physicist Alan Guth

performed calculations that led to the idea of

"cosmic inflation", a brief period of rapidexpansion in the early universe.

Inflation solves many problems with the

simple, original Big Bang. It explains why the universe is so big and so

smooth, why at least four different forces act

in it today, and where the large amountsof matter that make up the universe came

from


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Timeline

Copernicus

1473-1543

Tycho

1546-1601Kepler

1571-1630

Galileo

1564-1642 Newton

1642-1727


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The Scientific Revolution began with the European re-

discovery of Aristotle in the 12th and 13th centuries.

The earliest followers were burned at the stake asheretics because they went against church teachings.

Over time, teachings are combined with church doctrine

to form a watereddown science.


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In the Middle Ages, scientists were

mostly concerned with alchemy

standard chemistry problems

Roger Baconmost important

scientist of this time.

Invented gunpowderCame up with experimental

science

Despite this progress, people believedthe center of truth and existence was

God.


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The Scientific Revolution gains momentum during the

Renaissance with the works ofLeonardo da Vinci in the

middle of the 15th century, and Nicolaus Copernicus in

the 16th

century.Here, right here, in the eye, here forms, here colors,

right here the character of every part and everything

of the universe are concentrated to a single point.

How marvelous that point is! In this small space theuniverse can be completely reproduced and

rearranged in its entire vastness! (da Vinci)

Da Vinci is saying humans can see the universe in the

same way as God can encompass the universe. This is a

huge shift in the European thought! Now people were

willing to extend their views to new thingsscience.


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Arabic NumeralsDuring the Middle Ages, Europeans switched from Roman to

Arabic numerals. This is very important for the Scientific

Revolution. (Leonardo de Pisa)

Without this system, Copernicus could not have made his

mathematical calculations,

Arabic numerals use a place number system consisting of ten

numeralswhen these are used up, a new number is added.

Allows for fast calculations.

Try to multiply: MDMCXLVII BY CCCLXXII withoutconverting to Arabic Numerals


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AS THE WORLD TURNS

Geocentric Heliocentric


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Old Geocentric Theory

Sun rises Sun sets

Earth seems still

Official view of the Catholic Church

Geocentric: Earth-centered


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Proof:

Earth seems stationary

Sun seems to move across the sky

Bible quotes

Blind acceptance of Greek teachings

Man views himself as focus of the universe

Geocentric Theory


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Teachings of Aristotle300 BCE

World is made up of5

elements:

Earth, air, water, fire

and Quintessence

Earth does not rotate.


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Teachings of Aristotle

Clear, round, domes holdpalanets and stars.

Laws of Motion:

Things move by

weight or violent force


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Ptolemy 150 CE (Greek)

Agrees with Aristotle

Used math and Geometry to prove the

Geocentric Theory

Problems:

Planets must travel in loop orbits

Does not fit calendar

Math is forced


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NEW HELIOCENTRIC THEORY

The theory is introduced by Copernicus (1473

1543) a Polish astronomer and mathematician

Goal: Fix the problems of Ptolemy (Calendar

and math)

Make the sun thecenter and the

math works!


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HELIOCENTRIC THEORY

Sun is the center of the

universe.The earth revolves around the

sun and it rotates

Problem: It goes against the

teachings Aristotle and

common sense

On the Revolutions of the Celestial Spheres,

the book written by Copernicus is notpublished until after his death

T h B h (D i h


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Tycho Brahe (Danish

mathematician)

Really supported Aristotle-

wanted to prove

Copernicus wrong

Provides the mathematical

evidence that Copernicus

is correct.

Takes measurements for

over 20 years

Leaves his work toassistant Johannes

Kepler


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Tycho Brahe

Had two sets of astronomicaltables: one based on Ptolemys

theory and one based on

Copernicus.

He found that both tablespredictions were off by days

to a month.

He believed that much better

tables could be constructed

just by more accurate observations.

Tychos homemade instruments improved

measurement precision from ten minutes of arc (which

had held since Ptolemy) to less than one


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The skies change

Tycho observed 2 phenomena thatshowed the heavens DO change:

In November 1572, Tycho noticed

a new star in the constellationCassiopeia

Comet of 1577

Prior to this sighting,

comets were thought to be atmosphericphenomena because of the immutabilityof the heavens

But neither the star nor the comet changedposition as the observer moved, as expected for

atmospheric phenomena


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Johannes Kepler (15711630) German

The Proof: Used Brahes measurements

made one adjustment, and the math worked

perfectly!

Laws:

Planets travel in an Ellipse

Planets travel slow then

fast

Figure distance from sun by how long it

takes to revolve around sun. T = ka


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Galileo Tells The World

Galileo (15641642) Italian

On Motion:Things fall at an equal rate

Objects tend to stay in motion

Always liked proving

Aristotle wrong


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First Telescope

Sees Venus, moon, and 4 moons of

Jupiter

Visual proof Copernicus is correct


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Galileo tries to convince the

churchtold to be quiet

Wrote The Dialogs3 guystalking (Galileo, Copernicus,

and Ptolemy). Used the

book to prove his point, but

says Ptolemy is correct

W th f C th li Ch h


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Wrath of Catholic Church:

Defensive of CriticismGalileo put on trial

Found Guilty of heresygoing against thePope

Sentenced to house arrest until his death

Never figured

out gravity.


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The final pieceGravity!

Sir Isaac Newton 16421727

(England)

Explains orbit of planets:Gravity and Inertia

Created Calculus to help

explain

Finalized the Laws Of Motion


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Law #1 Objects in motion tend to stay in motion, objects at

rest tend to stay at rest. (Unless acted upon by another

force)


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Law #2 Change in

motion is proportional to

force


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Law #3 For each action

there is an equal and

opposite reaction


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Law of Gravity: All objects have a natural attraction

that varies with mass and distance

history of astronomy (timeline)

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