1. The Expanding Universe

2. The Doppler Effect  Relative motion affects wavelength affects wavelengthaffects wavelength  Cars  Trains  Stars!  Galaxies!

3. Galactic Observations  Edwin Hubble (1889-1953)  He observed that galaxies outside the Local Group were all red shifted red shiftedred shifted  Galaxies are moving away from us!  Galaxies farther away are moving faster – Hubble Expansion  The universe is expanding!

4. QUESTION  If all the galaxies around us are moving away from Earth, does this mean that the Milky Way is at the center?  Write your own prediction based on what we’ve learned in this unit

5. ACTIVITY Model the Expansion of the Universe

6. Analyze & Interpret  What pattern do you see in the five sets of measurements you took as you inflated the balloon?  Does this model help you answer the question and verify the prediction? Why or why not?

7. The Center of the Universe  If the Milky Way is not at the center of the Universe… Where is the center ?  Demo (1D) – Elastic band universe  Demo (2D) – Balloon Example  3D … Our Universe

8. The Big Bang (pg 374-375)

9. The Big Bang (t >= 0)  t = 0 … ENERGY  t = 1 to 10000 seconds Light elements (H, He, …)Light elements (H, He, …)  t = 400 million years The first stars and galaxies formThe first stars and galaxies form  t = 4 billion years Milky Way galaxyMilky Way galaxy  t = 14 billion years…TODAY!

10. The Big Bang (t < 0) NSA “No Such Animal” … not a valid question