The Big Bang!

1. The Big Bang! ESCI 518 Fall 2004

2. Origins • How and when did the: • universe form? • solar system / Earth form? • Moon form? • What were early Earth conditions? How Do We Know?

3. Origin of the Universe • Big Bang • occurred 15 billion years ago • model for the beginning of the universe

4. Building a Universe - infinitely dense point not governed by our physical laws or time - all matter and energy contained in one point http://rainbow.ldeo.columbia.edu/courses/v1001/7.html

5. Building a Universe - instantaneous filling of space with all matter http://rainbow.ldeo.columbia.edu/courses/v1001/7.html

6. Edwin Hubble • Universe is continuously expanding • Galaxy’s velocity is proportional to its distance (galaxies that are twice as far from us move twice as fast) • taken every galaxy the same amount of time to move from a common starting position to its current position

7. Hubble’s Evidence • Doppler shifting - wavelength emitted by something moving away from us is shifted to a lower frequency • Sound of a fire truck siren - pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you • Visible wavelengths emitted by objects moving away from us are shifted towards the red part of the visible spectrum • The faster they move away from us, the more they are redshifted. Thus, redshift is a reasonable way to measure the speed of an object (this, by the way, is the principal by which radar guns measure the speed of a car or baseball) • When we observe the redshift of galaxies outside our local group, every galaxy appears to be moving away from us - universe is expanding.

8. Evidence for Big Bang • Red shift - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to wavelengths being stretched • In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once - radiation left over from the Big Bang • In June 1995, scientists detected primordial helium in the far reaches of the universe - consistent with an important aspect of the Big Bang theory that a mixture of hydrogen and helium was created at the beginning of the universe

9. Building a Universe • 10-43 s - gravity separates from other forces - 10-28 centimeters • 10-35 to 10-32 s - fundamental particles - quarks and electrons - softball • 10-6 s - quarks combine into protons and neutrons - solar system • 1 s - electromagnetic and weak nuclear forces separate • 3 minutes - protons and neutrons combine into atomic nuclei • 105 years - electrons join nuclei to make atoms; light is emitted • 105-109 years - matter collapses into clouds, making galaxies and stars Orion Nebula - http://stardate.utexas.edu/resources/ssguide/planet_form.html

10. When Did the Universe Form? • 10 to 20 billion years ago (15) • How do we know? • spreading (Red Shift) • know distances, rates of retreat, relative positions • pervasive background radiation of 2.7°C above absolute zero • afterglow of the Big Bang Orion Nebula - http://stardate.utexas.edu/resources/ssguide/planet_form.html

11. How old is the universe? • Speed x time = distance • (distance of a particular galaxy) / (that galaxy’s velocity) = (time) • or • 4.6 x 10^26 cm / 1 x 10^9 cm/sec = 4.6 x 10^17 sec • ~ 15 billion years

12. Features of Our Solar System • in a spiral arm of the Milky Way Galaxy • Sun • 9 planets • 101 known moons (satellites) • a tremendous number of asteroids • most orbit the Sun between the orbits of Mars and Jupiter • millions of comets and meteorites • interplanetary dust and gases

13. Relative Sizes of the Sun and Planets

14. Solar System Configuration

15. Origin of Our Solar System Solar nebula theory • cloud of gases and dust • formed a rotating disk • condensed and collapsed due to gravity • forming solar nebula • with an embryonic Sun • surrounded by a rotating cloud

16. Embryonic Sun and Rotating Cloud • planetesimals have formed in the inner solar system • large eddies of gas and dust remain far from the protosun

17. The Planets • Jovian Planets • Jupiter • Saturn • Uranus • Neptune • large, composed of hydrogen, helium, ammonia, methane, relatively small rocky cores • Terrestrial Planets • Mercury • Venus • Earth • Mars • small, composed of rock, with metal cores – Pluto?