1. The Expanding Universe

2. Ballooniverse activity
Hubble’s discovery
Ballooniverse activity
Randomly draw or glue sticky dots around a small inflated balloon.
Measure the distance between dots
Blow it up again and re-measure.
Hubble

3. Partially inflated
Totally Expanded
Dot #
Initial distance from dot #1 ‘home’ galaxy
Final distance from dot #1 (after blowing up the balloon)
Change in the distance
(cm) 2 cm 3 4 5 6 7 8 9 10

4. Original distance from Milky Way (cm)20 18 16 14 12 10 8 6 4 2
Change in distance (cm)
Original distance from Milky Way (cm)

5. Hubble's Law. "The More Distant an Object is, the Greater is its Recessional Speed."

7. ANY galaxy in the universe would experience the same expansion away from them

8. The Expanding Universe
We’ve known since the early twentieth century that the galaxies are moving in an ordered way
Distance between galaxies is expanding.
ALL galaxies move away from each other in a “universal recession”
Recent observations show that this expansion is speeding up
At the 8:20 min. mark

9. at one time were they all together??
So…
If according to Hubble, the galaxies are all moving away from each other,
at one time were they all together??
Ask “What could have happened that would have had enough energy to move all of these galaxies then away from each other if gravity is a force that pulls them together?”

10. Ess. Question: What is the evidence that the universe expanded in a Big Bang?
PHENOMENON:
What did you observe?
What evidence do you have?
What is the recorded or measured data?
OBJECTS:
What are the objects that are interacting in the system?
MODEL of the UNIVERSE:
Describe the motion that in the model that explains your observations
1. Dots on the balloon spread away from each other.
The dots farther from the ‘home’ galaxy moved farther than the dots that were closer to home galaxy
2.  Spectra: Gases in the universe
3. Spectra: Red Shift of stars (Doppler Effect)
4. Background ‘noise’
galaxies
Universe
EMR waves of energy
Stars and interstellar gases
spectra

11. The Electromagnetic Spectrum (EMS) is the range of all types of radiation.
Radiation is ENERGY that travels at the speed of light and spreads out in all directions.
Radiation in a of stream of particles (photons) that travel as waves of different lengths and frequency.
Demo a slinky stretching out?

12. 3 types of spectra

13. By viewing the light from galaxies scientists can analyze the spectra and determine that most of the gases in the universe are the elements…
Suns’ Spectra
Hydrogen
Helium
These simplest atoms were the first gases formed after the big bang

14. Every element has a unique spectra that can be used to identify it.

15. Abundance of Elements in the Universe

16. Doppler Effect Definition:
The apparent change in frequency due to the relative motion of the source or receiver.
car horn
Big Bang Theory

17. Activity: Observe the Spectra of two galaxies and determine:
What do they have in common?
How are they different?
What may account for those differences?
Which one appears ‘Redshifted’? What could that mean?

18.
The light from most objects in the Universe is redshifted as seen from the Earth supports the idea that our Universe is expanding.
The redshift of an object can be measured by examining the absorption or emission lines in its spectrum.
These sets of lines are unique for each atomic element and always have the same spacing.
When an object in space moves toward or away from us, the absorption or emission lines will be found at different wavelengths than where they would be if the object was not moving (relative to us).
The change in wavelength of these lines is used to calculate the objects redshift.
Redshift is defined as the change in the wavelength of the light divided by the wavelength that the light would have if its source was not moving (called the rest wavelength).
annimation

19. As the balloon (galaxies and universe) expanded away,
it (the light waves from the stars) stretches-out
Becoming longer, more RED wavelengths

20. As an object moves AWAY from you the wavelengths stretch and lengthen making them longer frequency (red) wavelengths As an object moves TOWARD you the wavelengths compact and shorten making them higher frequency wavelengths like blue , violet and UV
The spectra lines from the galaxy shift toward the red if the object is moving away from you.
Stationary: not moving
Moving away from you: redshift

21. Are microwaves long or short wavelength radiation?
Are microwaves high or low frequency waves?
Are microwaves high or low temperature?
Are microwaves high or low energy?
Wavelength
DeGrasse Tyson and Microwave Radiation

22. Evidence: Background Microwave Radiation
the-big-bang-theory/ Neil DeGrasse Tyson

23. Ess. Question: What is the evidence that the universe expanded in a Big Bang?
PHENOMENON:
What did you observe?
What evidence do you have?
What is the recorded or measured data?
OBJECTS:
What are the objects that are interacting in the system?
MODEL of the UNIVERSE:
Describe the motion that in the model that explains your observations
1. Dots on the balloon spread away from each other.
The dots farther from the ‘home’ galaxy moved farther than the dots that were closer to home galaxy
2.  Spectra: Gases in the universe
3. Spectra: Red Shift of stars (Doppler Effect)
4. Background ‘noise’
galaxies
Universe
EMR waves of energy
Stars and interstellar gases
spectra

24. Concept Check
Most Galaxies are receding away from the Milky Way galaxy. (True, False)
Explain the evidence supporting the Big Bang:
Red Shift/Doppler
Microwave Radiation
3. Expanding Universe