and the Formation of Stars… The creation of our Universe The Big Bang and the Formation of Stars… The creation of our Universe

The Big Bang!!! Most scientists believe that 13.7 billion years ago the Universe was created by an event called the “Big Bang” (which was neither big nor loud) The Universe is…everything that exists!!! It all started from the “singularity”.

The Big Bang Theory states that: The singularity was where all matter and energy were concentrated in an area the size of an atom. The singularity (for reasons unknown) expanded rapidly creating matter and time. As matter spread outward it organized into atoms, molecules, and eventually Galaxies, stars, solar systems, planets, moons, asteroids, and everything else we know

Is the Universe static or dynamic??? The Age Mystery Is the Universe static or dynamic??? In 1929, Edwin Hubble discovered that almost all galaxies appeared to be moving away from us, meaning the Universe is expanding. There is no center, everything simply moves away from everything else. 2. He also noticed that the farther away a galaxy is, the faster it is moving away from us.

How do we know the 13.7 byo age of the Universe? Hubble discovered this by plotting distance vs. velocity on a graph. The inverse of the slope has the dimension of time, and can be taken as an estimate of the age of the Universe at around 13.7 byo. But how did he measure velocity and distance? The slope of this line is called the Hubble Constant.  V=D/T so T=D/V

We use electromagnetic radiation to examine the Universe. This is the EM spectrum as shown in ESRT. All radiation travels in EM waves.

Doppler Effect Hubble estimated the velocity and distance of other galaxies by using the…Doppler Effect The Doppler effect (or Doppler shift), named after the Austrian physicist Christian Doppler, who proposed it in 1842, is the change in frequency of a wave for an observer moving relative to its source. Fire engine - train

Doppler Effect We can see that stars/galaxies give off light. As they move, the wavelengths of light get shifted. If a galaxy moves away from you, the wave-lengths are stretched, increasing the wavelength – called a red shift If it moves toward you, the wave-lengths are squeezed together, decreasing the wavelength – called a blue shift

Types of Spectra

Hubble noticed that almost all galaxies display a red shift, meaning they are moving away from us. The galaxies do not look red, their spectra are simply shifted towards the long-wave, red light.

This means they are going away at a faster rate. He also noticed that the farther away the galaxy, the bigger the shift. This means they are going away at a faster rate.

This is supporting evidence for the Big Bang Theory The best explanation for this is that the Universe is expanding in all directions. This is supporting evidence for the Big Bang Theory

When you reverse this expansion you are left with the singularity. Reversing the expansion takes 13.7 billion years...the age of the Universe.

Other evidence for the Big Bang In 1964, Arno Penzias and Robert Wilson, discovered microwave background radiation that came from all directions at once - radiation left over from the Big Bang

Other evidence for the Big Bang In June 1995, scientists detected primordial helium in the far reaches of the universe This is consistent with an important aspect of the Big Bang theory that a mixture of hydrogen and helium was created at the beginning of the universe