Cosmic Times

1. Cosmic Times

2. The History Behind The Big Bang Theory • 1919 • Albert Einstein’s Theory of Relativity and Law of Gravitation was confirmed when the light from stars was bent around the sun • Einstein’s model also predicted that the universe is either expanding or contracting • He didn’t like this so he added a universal (or cosmological constant) so that the universe would be static • Sun is not the center of the galaxy • Galaxy is all-encompassing (only one galaxy) • Other “nebulae” are still a part of our galaxy

3. The History Behind The Big Bang Theory • 1929 • Edwin Hubble discovered that the “nebulae” observed, are much farther away than we expected, which means they are their own galaxies • Hubble also found that objects are moving away from us • Red shifted • Hubble found that objects are moving away, the universe is expanding. • Einstein’s original Theory of Relativity called for expansion, but instead he added the cosmological constant. Even after these new discoveries, Einstein was still not convinced.

4. The History Behind The Big Bang Theory • 1955 • Albert Einstein passed away • Cepheid variables had been used to calculate the distance of far objects, however, they had been used incorrectly. • There are two types of cepheid variables. • Combination of scientists determined that a nova is far different from a “super”nova. • Two types of supernovae. (composition) • Steady State vs. Big Bang • First studies of radio transmissions

5. The History Behind The Big Bang Theory • 1965 • Found microwaves (possible remnant of big bang) CMB • Ideas of open vs closed universe • In an attempt to calculate the mass of a galaxy, Burbidge and others found that there is more matter than can be see. (dark matter) • No current explanation (must be miscalculation) • Begin studying X-rays, but do not currently have a good way to study things above the atmosphere • No orbiting telescopes

6. The History Behind The Big Bang Theory • 1993 • In 1989, COBE found that the CMB was not completely uniform. • Big Bang Theory gets a tune-up: Inflation • Following Big Bang, Inflation was extremely fast and hot expansion. After inflation, everything began to slow down and cool off. • ROSAT found an area of extremely hot gas. • Should have diffused away, so something must be holding it in place. • Beginnings of dark matter • Discovery of two different types of supernovae • Confirmation of existence of gravitational waves, predicted by Einstein

7. The History Behind The Big Bang Theory • 2006 • Discovery of Dark Energy in addition to Dark Matter • Dark energy is speeding up the expansion of the universe? • Einstein’s cosmological constant actually accounted for this • Scheduled launch for JDEM is 2013 • Study Dark energy

8. Big Bang Theory • Historically… • 1912 - Vesto Slipher • Measured the first Doppler shift (red shift) • Object in space is moving away from us • 1922 – Alexander Friedman • Used Einstein’s relativity to show that the universe might be expanding • 1924 – Edwin Hubble • Measured the distance to other galaxies

9. Big Bang Theory • Historically… • 1927 – Georges Lemaitre • Predicted the recession of nebulae was due to the expanding • 1931 – Georges Lemaitre • Followed the logical backward thought… • So if the universe is far apart now, at some time in the past it was very close • Primeval atom • Before which time & space did not exist

10. Big Bang Theory • Historically… • 1924 – Edwin Hubble • Series of distance indicators • 1929 – Hubble’s Law • the velocity at which various galaxies are receding from the earth is proportional to their distance from us • The farther away they are, the faster they are moving

11. Big Bang Theory • Historically… • 1930s (through 1960s) • Many Non-Standard Cosmological Theories were introduced • Any cosmological model of the universe that is an alternative to the Big Bang • Many have disputed parts of the Big Bang theory or the Big Bang theory as a whole

12. Big Bang Theory • Some opponents to Big Bang • Newtonian cosmology • Lorentzian universes • static universe • Machian universe • Gödel's universe • MOND – Modified Newtonian Dynamics • TeVeS - Tensor-vector-scalar gravity • Steady state theories • Tired light • Dirac large numbers hypothesis • Plasma cosmology

13. Cosmic Microwave Background Radiation • Possibly the single most influential factor that contributed to the general acceptance of the Big Bang theory • The discovery and confirmation of the cosmic microwave background radiation in 1964 secured the Big Bang as the best theory of the origin and evolution of the cosmos

14. The Big Bang Theory • The universe, originally in an extremely hot and dense state (singularity or primeval atom), • That expanded rapidly, (the big bang), • And has since cooled by expanding to the present state, • And continues to expand today

15. What happens from here? • Two main theories on the universe as a whole: • Open • Closed

16. Open Universe • The term open universe refers to a universe which has no physical or practical barriers to it's continued expansion. • If the universe is indeed open, then the universe can continue expanding forever. • Big Rip • Big Freeze • If the universe cannot expand forever, then some barrier must exist to prevent the expansion.

17. Closed Universe • The second model of the universe is one in which the curvature of space is roughly spherical, because of that the universe has a finite size • An object moving in a straight line in a closed universe would eventually return to its starting point.

18. Closed Universe • According to most current cosmological theories, the universe is closed if it is sufficiently dense, and therefore possesses enough gravitational force to stop or reverse the expansion started by the big bang • Big Crunch • Big Bounce

19. 4 Ways for the Universe to End • The Big Rip: The big rip is a theory that occurs following general relativity, it states the universe will continue to expand at an accelerated rate, eventually reaching a point where life cannot exist. The accelerated expansion occurs due to dark energy, leading to everything being ripped apart into elementary particles.

20. 4 Ways for the Universe to End • The Big Freeze: The big freeze theory suggests that the universe will continue to expand until it becomes too cold to support life. This can only occur for certain shapes of the universe, which allow it to expand forever. The heat death theory is related to this and will occur for all three models of space, and requires a minimum temperature to be reached. It suggests everything is evenly distributed and life cannot be supported.

21. 4 Ways for the Universe to End • The Big Crunch: The big crunch assumes that the average density of the universe will stop it expanding and it will begin to contract. This may cause it to collapse into a singularity, which may then lead to a big bang creating another universe. If this is repeated then the universe is an infinite cycle of universes starting in big bangs and ending in big crunches.

22. 4 Ways for the Universe to End • Big Bounce: This suggests that we might be living in the first of all universes, but are equally likely to be living in the 2 billionth universe (or any of an infinite other sequential universes). • Similar to the Big Crunch (repeated)