1. The Expanding Universe???

2. The Expanding Universe???

3. The Expanding Universe???
Big Bang Theory -- the scientific theory of the universe’s earliest moments, stating that all the matter in our observable universe came into being at a single moment in time as an extremely hot, dense mixture of subatomic particles and radiation.

4. The Expanding Universe???
There are 4 evidences that led scientists to widely accept the Big Bang theory.

5. The Expanding Universe???
There are 4 evidences that led scientists to widely accept the Big Bang theory.
Hubble’s Law
Cosmic Microwave Background (CMB)
Galaxies that are spread apart
Chemical Composition of the Universe

6. The Expanding Universe???
Hubble’s Law

7. Hubble’s Law Redshift – Signifies object moving away
Blueshift – Signifies object moving towards

8. Hubble’s Law
TWrT
Galaxy

9. Hubble’s Law
TWrT
1) Which direction is this galaxy traveling?
Galaxy

10. Hubble’s Law
TWrT
1) Which direction is this galaxy traveling?
Galaxy

11. Hubble’s Law Edwin Hubble
(1889 – 1953) – an American astronomer who discovered galaxies outside of the Milky Way.

12. Hubble’s Law

13. Hubble’s Law

14. Hubble’s Law

15. Hubble’s Law
luminosity – a measurement of the power output (absolute brightness) of an object (Watts).
apparent brightness – the brightness of a star as seen from Earth.

16. Hubble’s Law
Cepheid Variable Star -- a pulsing star that has a known and defined luminosity that is directly related to the pulsation period.
(the longer the pulsation period the more luminous the Cepheid star)

17. Hubble’s Law
TWrT

18. Hubble’s Law
TWrT
1) Cepheid A pulses over a period of 2 days. Cepheid B pulses over 2 weeks. Which has a greater luminosity?
2) When you look at the sky, Cepheid A and B have the same apparent brightness. Are they the same distance, or is one further than the other?

19. Hubble’s Law B A

20. Hubble’s Law
Challenge

21. Hubble’s Law
Challenge
Find the Cepheid

22. Hubble’s Law
Challenge
Find the Cepheid

23. Hubble’s Law
1.2 million light years away
40,000 light years away

24. Hubble’s Law Velocity (away) (km/s, thousands) (ly, millions) 54.0
48.0
42.0
36.0
30.0
Velocity (away) (km/s, thousands)
24.0
18.0
12.0
6.0
326
652
978
1305
1631
1957
2283
2609
(ly, millions)

25. Hubble’s Law Velocity (away) (km/s, thousands) (ly, millions) 54.0
48.0
42.0
36.0
30.0
Velocity (away) (km/s, thousands)
24.0
18.0
12.0
6.0
326
652
978
1305
1631
1957
2283
2609
(ly, millions)

26. Hubble’s Law Velocity (away) (km/s, thousands)
54.0
48.0
42.0
m = 22 km/s / 1 million ly
36.0
30.0
Velocity (away) (km/s, thousands)
24.0
18.0
12.0
6.0
326
652
978
1305
1631
1957
2283
2609
(ly, millions)

27. Hubble’s Law Hubble’s Law: v = H0d H0 = 22 km/s / 1 million ly
54.0
Hubble’s Law: v = H0d
48.0
H0 = 22 km/s / 1 million ly
42.0
36.0
30.0
Velocity (away) (km/s, thousands)
24.0
18.0
12.0
6.0
326
652
978
1305
1631
1957
2283
2609
(ly, millions)

28. Hubble’s Law
Hubble’s Law -- the farther away a galaxy is, the faster it moves away from the observer.

29. Hubble’s Law
TWrT

30. Hubble’s Law
TWrT
1) Think of a situation where you are in a pitch black environment and you see little lights all around you moving away from you, what could be happening?

31. The Expanding Universe???

32. The Expanding Universe???
Forwards in Time

33. The Expanding Universe???
Backwards in Time

34. The Expanding Universe???
Backwards in Time

35. The Expanding Universe???

36. Cosmic Microwave Background (CMB)

37. Cosmic Microwave Background (CMB)

38. Cosmic Microwave Background (CMB)

39. Cosmic Microwave Background (CMB)
The mathematics predict that this happened approximately 378,000 years after the BB.

40. Cosmic Microwave Background (CMB)
Universe gets colder as it expands.

41. Cosmic Microwave Background (CMB)

42. Cosmic Microwave Background (CMB)
Arno Penzias & Robert Wilson – discovered the CMB in 1964 at Bell Labs in Holmdel, NJ. They were awarded the Nobel Prize for Physics in 1978 for this discovery.

43. Cosmic Microwave Background (CMB)
WMAP satellite

44. The CMB is about 2.73 K and varies by about .00001 K across the sky.
Cosmic Microwave Background (CMB)
The CMB is about 2.73 K and varies by about K across the sky.

45. Cosmic Microwave Background (CMB)
The mathematics that predicts this temperature also predicts that the light is about 13.8 billion years old.

46. Galaxies that are spread apart
The slight variation of temperature would lead to galaxies that were separate and spread apart.

47. Galaxies that are spread apart
The slight variation of temperature would lead to galaxies that were separate and spread apart.

48. Galaxies that are spread apart
TWrT

49. Galaxies that are spread apart
TWrT
1) Think of a situation where you are in a very small forest (the size of a yard), when you look in any direction, what do you see?
2) Think of a situation where you are in an infinite forest, when you look in any direction, what do you see?

50. Galaxies that are spread apart
If the Universe were infinite with an infinite number of stars, anywhere we looked, we would see a wall of stars. The whole sky would be bright, day or night.

51. Galaxies that are spread apart
Since we see separate galaxies that are spread apart, there are 2 things we can conclude.
1) The Universe is changing and not infinite.
and / or
2) There are a finite number of stars.

52. Galaxies that are spread apart
Since we see separate galaxies that are spread apart, there are 2 things we can conclude.
1) The Universe is changing and not infinite.
and / or
2) There are a finite number of stars.
Scientists have widely accepted both of these ideas which both point to the Big Bang.

53. Chemical Composition of the Universe
75% hydrogen
25% helium

54. Chemical Composition of the Universe
Space is too cold to make helium. Only the inside of a star is hot enough to make helium.
The helium from all the stars could only produce at most 10% of the helium in the Universe.
Where did the helium come from?

55. Chemical Composition of the Universe
TWrT

56. Chemical Composition of the Universe
TWrT
1) What type of environment is needed to make helium?
2) Come up with a theory that describes a situation hot enough to make enough helium to account for the 25% we see in the Universe today.

57. Chemical Composition of the Universe

58. Chemical Composition of the Universe
The mathematics of the Big Bang Theory predict an environment hot enough to make helium and predicts a 75% hydrogen 25% helium ratio.

59. Chemical Composition of the Universe