1. The Expanding Universe

2. REVIEW: The Local Group and Other Galaxy Clusters
Galaxies form clusters because of gravitational attraction
Newton’s Law of Gravity is universal…..
It works for the entire universe
Within 3 million light-years of the Milky Way lie about 20 galaxies
This is the Local Group

3. Our Local Group
Small group of galaxies in close proximity, attracted by gravitational influence

4. Virgo Cluster ClusterCluster
100’s of galaxy clusters

5. SUPERclusters
Clusters of clusters that are also gravitationally attracted to one another
Together they form superclusters

6. But how do all of these clusters react to each other…?

7. 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.

8. 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

9. Original distance from Milky Way (cm)
The assigned number of the star will have nothing to do with its graphing. It is just an assigned number for you to keep track of your measurements. 20 18 16 14 12 10 8 6 4 2
Change in distance (cm)
Original distance from Milky Way (cm)

10. What evidence do you have? What is the recorded or measured data?
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
Balooniverse Lab:
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: Red Shift of stars (Doppler Effect)
3. Spectra: Gases in the Universe
4. Background ‘noise’
Balloon
 Marker
 Ruler
 Air

11. 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

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

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

20. http://www.youtube.com/watch?v=hVApTLE7Csc Hubble
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
 Scientists can take pictures of galaxies/receive waves of “energy” and can observe that galaxies are moving away (receding) in an orderly way
2.  Spectra: Red Shift of stars (Doppler Effect)
3. Spectra: Gases in the Universe
4. Background ‘noise’
Balloon
 Marker
 Ruler
 Air
Telescope/ instrumentation
Galaxies
 (Hubble’s Law)
Hubble

21. 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?”

22. Evidence of The Big Bang
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
 Scientists can take pictures of galaxies/receive waves of “energy” and can observe that galaxies are moving away (receding) in an orderly way
2.  Spectra: Red Shift of stars (Doppler Effect)
3. Spectra: Gases in the Universe
4. Background ‘noise’
Balloon
 Marker
 Ruler
 Air
Telescope/ Instrumentation
Galaxies
 (Hubble’s Law)
If all of the galaxies are moving away from each other, then we can assume at one point they all had to be close together. There had to have been a force strong enough to overcome gravity and force all of these galaxies apart to the point where they are still moving away. THE BIG BANG!!

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

24. 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?

25. Evidence: Background Microwave Radiation
P: Scientists discovered interference (waves of energy) coming from apparent empty regions of space
the-big-bang-theory/ Neil DeGrasse Tyson

26. 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
 Scientists can take pictures of galaxies/receive waves of “energy” and can observe that galaxies are moving away (receding) in an orderly way
2.  Spectra: Red Shift of stars (Doppler Effect)
3. Spectra: Gases in the Universe
4. Background ‘noise’
Scientists discovered interference (waves of energy) coming from apparent empty regions of space
Balloon
 Marker
 Ruler
 Air
Telescope/ instrumentation
Galaxies
Microwave waves
Large “Horn” (antenna)
 (Hubble’s Law)
If all of the galaxies are moving away from each other, then we can assume at one point they all had to be close together. There had to have been a force strong enough to overcome gravity and force all of these galaxies apart to the point where they are still moving away. THE BIG BANG!!

27. Evidence: Background Microwave Radiation
P: Scientists discovered interference (waves of energy) coming from apparent empty regions of space
M: the energy (microwave waves) has to be emitted from something so if there is nothing there, then it must be left over energy powerful enough to still exist

28. 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

29. 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
 Scientists can take pictures of galaxies/receive waves of “energy” and can observe that galaxies are moving away (receding) in an orderly way
2.  Spectra: Red Shift of stars (Doppler Effect)
3. Spectra: Gases in the Universe
4. Background ‘noise’
Scientists discovered interference (waves of energy) coming from apparent empty regions of space
Balloon
 Marker
 Ruler
 Air
Telescope/ instrumentation
Galaxies
Microwave waves
Large “Horn” (antenna)
 (Hubble’s Law)
If all of the galaxies are moving away from each other, then we can assume at one point they all had to be close together. There had to have been a force strong enough to overcome gravity and force all of these galaxies apart to the point where they are still moving away. THE BIG BANG!!
The energy (microwave waves) has to be emitted from something so if there is nothing visible there, then it must be left over energy powerful enough to still exist (power like that from a huge explosion): THE BIG BANG!! And with microwaves being of low energy, the power source that initially dispersed them must have been immense!

30. The Universe is Receding
ALL galaxies are moving away from each other.
The farther distance the galaxy is from us, the faster its receding. (Hubble’s Law)
How do we know this? Redshift!

31. 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?

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

33. 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

34. 3 types of spectra
*an unbroken band of colors, which shows that its source is emitting light of all visible wavelengths
*a series of unevenly spaced lines of different colors and brightness; shows that the source is emitting light of only certain wavelengths
*a continuous spectrum crossed by dark lines; these lines form when light from a glowing object passes through a cooler gas, which absorbs some of the wavelengths

35. 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).

36. Activity: Observe the Absorption 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?

37. 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
 Scientists can take pictures of galaxies/receive waves of “energy” and can observe that galaxies are moving away (receding) in an orderly way
2.  Spectra: Red Shift of stars (Doppler Effect: the apparent change in frequency due to the relative motion of the source or receiver) )
(See above) It is observed that galaxies, when compared over different times, show a “red shift”
3. Spectra: Gases in the Universe
4. Background ‘noise’
Scientists discovered interference (waves of energy) coming from apparent empty regions of space
Balloon
 Marker
 Ruler
 Air
Telescope/ instrumentation
Galaxies
Galaxies’ Spectrum of light (spectrogram)
Spectroscope
Microwave waves
Large “Horn” (antenna)
 (Hubble’s Law)
If all of the galaxies are moving away from each other, then we can assume at one point they all had to be close together. There had to have been a force strong enough to overcome gravity and force all of these galaxies apart to the point where they are still moving away. THE BIG BANG!!
Increasing distance results in increased wavelengths which shift toward the red end on a light spectrum
the energy (microwave waves) has to be emitted from something so if there is nothing there, then it must be left over energy powerful enough to still exist (power like that from a huge explosion) THE BIG BANG!!
Ess. Question: What is the evidence that the universe expanded in a Big Bang?

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

39. 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

40. Abundance of Elements in the Universe

41. 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
 Scientists can take pictures of galaxies/receive waves of “energy” and can observe that galaxies are moving away (receding) in an orderly way
2.  Spectra: Red Shift of stars (Doppler Effect: the apparent change in frequency due to the relative motion of the source or receiver) )
(See above) It is observed that galaxies, when compared over different times, show a “red shift”
3. Spectra: Gases in the Universe
By viewing the light from the galaxies, scientists have analyzed the spectra and determined that most of the gases in the universe are the elements hydrogen and helium.
4. Background ‘noise’
Scientists discovered interference (waves of energy) coming from apparent empty regions of space.
Balloon
 Marker
 Ruler
 Air
Telescope/ instrumentation
Galaxies
 Galaxies’ Spectrum of light (spectrogram)
Spectroscope
Galaxies’ Spectrum of light (spectrogram)
Hydrogen
Helium
Microwave waves
Large “Horn” (antenna)
 (Hubble’s Law)
If all of the galaxies are moving away from each other, then we can assume at one point they all had to be close together. There had to have been a force strong enough to overcome gravity and force all of these galaxies apart to the point where they are still moving away. THE BIG BANG!!
Increasing distance results in increased wavelengths which shift toward the red end on a light spectrum
These simplest atoms, hydrogen and helium, were the first gases formed after THE BIG BANG!
the energy (microwave waves) has to be emitted from something so if there is nothing there, then it must be left over energy powerful enough to still exist (power like that from a huge explosion) THE BIG BANG!!
Ess. Question: What is the evidence that the universe expanded in a Big Bang?

42. 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