GALILEO GALILEI

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GALILEO GALILEI

• 1564-1642

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The OLD View of the UNIVERSEPtolemaic
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The OLD View of the UNIVERSE
The moon
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The OLD View of the UNIVERSE
The sun
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The OLD View of the UNIVERSE
Mercury Venus Mars Jupiter Saturn
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The OLD View of the UNIVERSE
The stars
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Reasons for supporting the old view

• Religious beliefs Humans were Gods creation and
  so must be at the centre of the universe.
• Some passages in the bible implied that the sun
  was in motion across the sky.

This may have been good enough reason for many to
believe in an earth centred view but for
scientists of the time their were further
issues..
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Reasons for supporting the old view

• Everyday we see the sun rise, move across the
  sky and set.

It looks as though the sun moves around us?
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But what would the movement of the sun in the sky
look like if we (the earth) were rotating on our
axis and orbiting the sun?

• It would look the same!!!!
• So this cant be the key reason for believing
  that the sun orbits the earth.

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The key is our understanding of MOTION!

• Learned people of the time believed that if the
  earth was hurtling through space we would be able
  to feel that motion.
• Surely an object cannot keep moving unless a
  force is pushing/pulling it along, and we would
  be aware of that force????
• OUR MODERN UNDERSTANDING OF MOTION SAYS.NO
• A steady/straight motion requires no forces to be
  involved.

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The argument to support the old view

• If the earth was moving surely we would be
  able to feel the motion
• Falling objects would appear to fall sideways
  wouldnt they?

Surely an apple is no longer pulled along with
the earth and tree as it starts to
fall!... The path you would observe.
MOTION OF EARTH ( you and the tree)
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Galileo realised that our understanding of motion
was wrong.
The apple continues to move sideways with the
earth and the tree as it falls.
The idea that things need to be pulled along to
keep them moving was wrong
To anyone standing on earth the apple appears to
fall straight down!
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If you are being smart.

• You may be saying..but if we are rotating and
  moving round the sun we are not moving in a
  straight line, but a circle!

Can you name the force that we experience and
allows us to hold our circular path..????
WE WOULD FEEL THIS FORCE.
FOR US TO MOVE IN A CIRCLE WE MUST EXPERIENCE A
FORCE THAT PULLS US TOWARDS THE CENTRE OF THIS
CIRCLE.
GRAVITY !!!
All this makes the explanation more complicated,
but that s all.
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Problems for the old view

• The observations of the other planets didnt
  match the model.
• If you plot the path of Venus across the sky it
  looks a bit like this
• Surely it should move in a straight line!

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Other problems for the old view

• Galileo had created a telescope that showed
• Moons around Jupiter
• Craters and Mountains on the moon
• Spots on the sun
• Everything should move around the earth. The
  planets/sun and moons were supposed to be perfect
  and smooth!

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Birth of a new view

• 1530 Nicholas Copernicus came up with a sun
  centred model.
• He didnt publish it until he was on his deathbed!

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The New View of the UNIVERSECopernican
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The New View of the UNIVERSE
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The New View of the UNIVERSE
Now all the planets orbits around the sun
Stationary picture
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The New View of the UNIVERSE
Stationary picture
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Galileo

• He spoke out in favour of the Sun centred model
  of the universe.
• In 1633 he was put on trial by the Inquisition
  and found guilty of heresy.
• He was sentenced to life imprisonment which was
  later reduced to permanent house arrest

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