AS101 Lecture Notes - Lecture 2: Cosmic Microwave Background, Big Bang, Rotational Energy

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11 Feb 2016
Astronomy Lecture #2
Temperature of Space
- -273 degrees – absolute zero.
- Not in our solar system – heat emitted from the sun.
- Temperature of space between stars.
- Andrew McKellar – looked for rotational energy in molecules in space to determine
temperature of space (are the interstellar molecules using energy?)
- Found that molecules are tumbling about – deducted that the temperature of space was
actually -270 degrees.
- Astronomers studying the origins of our universe picked up unexplainable noise with
their radio telescope – studying radio waves. Noise was persistent no matter the direction
in which the telescope was pointed.
- In collaboration with another astronomer from Princeton, they deduced that there is left
over sound energy spreading through the universe left over from the big bang –
measuring to precisely 3 degrees (in agreement with McKellars calculations).
- Static noise – background radiation (Cosmic microwave background radiation) – sound
of the birth of the Earth.
Fundamental Questions of Modern Astronomy
How did we come to be?
- The big bang theory of an initial cosmic explosion is the most widely accepted theory of
the origin of the universe.
- Matter and energy was hurled in all directions.
- The simplest elements hydrogen and helium initially dominated (most abundant initially)
- Most matter in space (living stars) is made of hydrogen and helium.
- Helium was initially discovered in the sun, then on Earth.
- Gravity caused matter to be drawn together to create stars, galaxies and clusters.
- Before the big bang, even the forces we know today, such as gravity did not exist.
- When massive stars die, they explode – called supernova explosions – most energetic
explosions we know of.
- So much energy released – heavier elements (in periodic table) are formed when a star
starts to die.
- Eventually these elements form new stars and planets (we are recycled by the
- Stars manufacture more complex elements such as nitrogen and oxygen.
- When the star dies, they are expelled into space… to form new stars and planets.
- Most of the atoms in our bodies were created in the core of a star.
What is our motion in the Universe?
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