The Big Bang Theory

1. The Big Bang Theory The Beginning of All

2. Big Bang Theory • Humans have been wondering about the beginning of time for a LONG time • How did this all begin? • Creation of the universe had several theories • 1927 – Georges Lemaitre: priest and astronomer– first one to develop the idea of a “Big Bang” • Edwin Hubble confirmed his findings a couple of years later.

3. Important Terms • Density: amount of mass in a given volume • The more “stuff” there is in one spot, the more dense it is. Low Density High Density

4. Important Terms • Gravity: attraction between physical bodies with a force relative to their mass GRAVITY Lots of GRAVITY

5. Singularity • Singularity: a point of INFINITE density and INFINITE gravity GRAVITY GRAVITY GRAVITY GRAVITY

6. Big Bang Theory • The theory that states that the universe began from an extremely dense and hot state and continues to expand today. (13.7 billion years ago) Galaxies Singularity

7. Evidence for Big Bang Theory • 1. Hubble’s Law • All objects observed from Earth exhibit a red shift (they are moving away from us) • This is the same as the Doppler Effect • The speed of objects is proportional to their distance from Earth • If they are twice as far, they are moving twice as fast!

8. Expanding Universe • Rising Raisin Bread Analogy

9. Hubble’s Law and Doppler Effect Originally discovered by the Austrian mathematician and physicist, Christian Doppler (1803-53), this change in pitch results from a shift in the frequency of the sound waves.

10. Doppler Effect The electromagnetic radiation emitted by a moving object also exhibits the Doppler effect. • Redshift: A phenomenon where wavelengths get larger and light is shifted to the red end of the spectrum.

11. Blueshift: This spectrum shows hydrogen shifted to the blue end of the spectrum. This star is moving toward Earth. Redshift: This spectrum shows hydrogen shifted to the red end of the spectrum. This star is moving away from Earth. The radiation emitted by an object moving toward an observer is squeezed; its frequency appears to increase and is therefore said to be blueshifted. In contrast, the radiation emitted by an object moving away is stretched or redshifted. Blueshiftsand redshifts exhibited by stars, galaxies and gas clouds also indicate their motions with respect to the observer.

12. Evidence for Big Bang Theory • 2. Cosmic Background Radiation (microwaves) • “Leftover” radiation from initial explosion • Big Bang explosion was very, very hot • Leftover heat must exist! • Same radiation comes from every corner of the universe • 2.725 degree Kelvin (-454.765 degree Fahrenheit, -270.425 degree Celsius)

13. Evidence for Big Bang Theory • 2. Cosmic Background Radiation (microwaves) • Same temperature from every direction • Can be captured with a TV antenna (static “snow”)

14. Evidence for Big Bang Theory The first satellite built dedicated to cosmology. Its goals were to investigate the cosmic microwave background radiation (CMB) of the universe and provide measurements that would help shape our understanding of the cosmos.

15. Evidence for Big Bang Theory The "famous" map of the CMB formed from data taken by the COBE spacecraft. Won the two scientists (Penzias and Wilson) the Noble Prize for Physics in 1978.

16. Evidence for Big Bang Theory • 3. Abundance of “light” elements • Hydrogen and Helium found everywhere in the observable universe • First two elements created after the Big Bang

19. Another Look at the Big Bang

21. Hubble Ultra Deep Field