Formation of the Universe

1. Formation of the Universe

2. Cosmology • Cosmology is the study of the • Nature, • Structure, • Origin, • And fate of the universe.

3. Universe in a Nutshell

4. Big Bang Theory • The Big Bang Theory was first proposed in the late 1920’s. • It states that there was an infinitely small, infinitely dense point that contained everything that is the universe. • This singularity was incredibly dense and hot.

5. Big Bang Theory • The Big Bang is believed to have occurred between 10 and 15 billionyearsago. (Most scientists agree that the universe is 13.7 billion years old.) • Two elements, hydrogen and helium were created in the primordial fireball, along with small amounts of lithium and beryllium.

6. Georges Henri Lemaitre • Late 1920’s • Belgian Astronomer • “Father of the Big Bang” • First suggested that the universe formed from a singularity but had no evidence.

7. Edwin Hubble • 1929 • Studied light given off by galaxies. • Proposed Hubble’s Law after studying these galaxies.

8. Hubble’s Law • The rate at which a galaxy is moving is directly proportional to its distance from us. • In other words, the farther away a galaxy is from us, the faster it travels away from us. • Thus the universe is expanding.

9. Steady State Theory • Opposes the Big Bang Theory • Steady State Theory states that the universe has always been essentially the same as it is today and that it will continue that way forever.

10. Steady State Theory • As matter moves apart, new matter is created to fill the gaps. • Cosmic Background Radiation in the universe ruled out the Steady State Theory.

11. Evidence of the Big Bang 1. The expansion of the universe Hubble 1929-galaxies were generally receding

12. Evidence of the Big Bang 2. The abundance of the light elements H, He, Li -BBT predicts that these were fused from protons and neutrons in the first few minutes after the BB.

13. Evidence of the Big Bang 3. The cosmic microwave background (CMB) radiation -Early universe was very hot. - CMB radiation is the remnant heat from the Big Bang.

14. Limitations of the Big Bang 1. Structure in the universe Doesn’t explain how structures like stars and galaxies came to exist in the universe.

15. Limitations of the Big Bang 2. Fluctuations in the cosmic microwave background (CMB) radiation -The temperature of the CMB is observed to vary slightly across the sky. -What produced these fluctuations? -How do they relate to stars and galaxies?

16. Limitations of the Big Bang 3. The inflationary universe -A very short, rapid burst of growth in the very early universe (“inflation”) - Why?

17. Big Picture Timeline

19. What’s the Universe Made Of? • 4 % Atoms • 22% Cold Dark Matter • 74% Dark Energy

20. What is Dark Matter? • Matter that interacts only weakly with ordinary matter. • Never been directly observed in the laboratory, its existence has long been suspected.

21. What is Dark Energy? • Bizarre form of matter, or a property of the vacuum itself • Characterized by a large, negative pressure (repelling force). • Only form of matter that can cause the expansion of the universe to accelerate, or speed up.

23. Fates of the Universe • Open Universe • Closed Universe • Flat Universe • Accelerating Universe

24. Fates of the Universe • Open Universe – little gravity; outward expansion goes on forever • Closed Universe – gravity will eventually halt the expansion and draw everything. Also known as the Big Crunch

25. Fates of the Universe • Flat Universe – expansion slows down but never stops • Accelerating Universe - expansion of the universe will speed up. (Most accepted theory because of dark energy.)

27. Other Galaxies

28. Types of Galaxies • Spiral • Barred Spiral • Elliptical • Irregular

29. Hubble’s Diagram of Galaxy Types

30. 1. Spiral Galaxies Type Sa Type Sb Type Sc

32. Spiral Galaxies Seen Edge-on M104: Sa galaxy NGC 891: Sb galaxy NGC 4631: Sc galaxy

33. Variety in Spiral Arms M33: A Spiral Galaxy with Flocculent Spiral Arms – created by explosions. M74: a Grand Design Spiral Galaxy – created by waves, like ripples in water.

34. 2. Barred Spiral Galaxies NGC 1365: SBc galaxy M83: SBb galaxy

35. 3. Elliptical Galaxies NGC 4526: E7 galaxy M49: E4 galaxy

36. 4. Irregular Galaxies Large Magellanic Cloud, Irr 1 galaxy NGC 4485 (Irr 2) and NGC 4490 (Sc) galaxies

37. Galaxies are Clumped in Space • Occur in Clusters that are gravitationally bound. • Bound by gravity to each other, and can collide. • Milky Way belongs to a Cluster called “The Local Group.” • Clusters of galaxies occur in bigger groups called Superclusters (not gravitationally bound). • All the Clusters are moving away from each other as the Universe expands.

38. A Cluster of Galaxies

39. The Local Group – Our Cluster Our Galaxy belongs to a poor, irregular (wimpy) cluster – consisting of about 40 galaxies – called the Local Group.

40. Colliding Galaxies • Clustered galaxies can collide. • They can pass through each other or combine. • The individual stars in the colliding galaxies do not hit each other, but the huge clouds of gas and dust do collide.

41. Colliding Galaxies

42. Colliding Galaxies

43. The Universe is Expanding • The Redshift of Superclusters shows us that the Universe is expanding. • The farther away a galaxy is from us, the faster it moves away from us. • GALAXY SPEED = GALAXY DISTANCE x HUBBLE’S CONSTANT (H0).

44. Redshift Explained -As the universe expands the frequency of waves decreases. -Wavelength increases -Coloring of light shifts towards the red color. -Doppler Effect- Frequency decreases and wavelength increases as waves move farther from the source; energy spreads out

46. The Expansion of the Universe –Cosmological Redshift Space itself is expanding.

47. Hubble’s Law The farther away a galaxy is from us, the faster it moves away from us: GALAXY SPEED = GALAXY DISTANCE x HUBBLE’S CONSTANT (H0).

48. The Milky Way – Side View

49. The Milky Way – Top View

50. How We Map the Galaxy Radio waves from different gas clouds show slightly different Doppler shifts, permitting astronomers to sort out the gas clouds and map the Galaxy.