9.2 The Universe Homework: page 376 # 2, 3, 5, 6

KEY CONCEPTS: Edwin Hubble’s observations of galaxies led to the discovery that the universe is expanding Exploring space has generated valuable spinoff technologies The most widely accepted theory of the beginning of the universe is called the big bang theory. According to this theory, an unimaginably tiny volume of space suddenly and rapidly expanded to an immense size about 14 billion years ago

The Universe - Astronomer Edwin Hubble observed that distant galaxies were moving away from the Milky Way. - How did he know this and what did it mean???

The Doppler Effect Waves in front bunch up (short wavelength) Waves behind spread-out (long wavelength) The spectral lines were slightly displaced from their normal positions. The change in frequency of a light source due to its motion relative to the observer.

Redshift and Blueshift - light travels as a wave – blue light has short wavelengths - red light has long wavelengths

- the wavelength of light coming from galaxies all around is getting longer (towards the red wavelength of light) - galaxies are moving apart, but they themselves do not expand because of gravity - Hubble observed that most galaxies are redshifted, this means they are moving away from us in the Milky Way galaxy - the farther away the galaxy is from us, the faster it moves. This is called the Hubble Law

Big Bang Theory - about 14 billion years ago, all the matter of the entire universe exploded outwards from one small extremely hot mass under tremendous pressure - the “beginning” (time zero) - what happened before this is not known

Evidence for the Big Bang Theory 2. Scientists detected unexpected radiation (Cosmic Microwave Background) coming from all directions in space that could be the remains of the enormous amount of energy that exploded outwards at the time of the Big Bang. 1. Expanding universe

The Large Hadron Collider (LHC) The largest particle accelerator ever built. It will recreate conditions just after the Big Bang. What Is It?

How Does It Work? Two proton beams will be steered by magnets in opposite directions around a circular tunnel at close to the speed of light. At designated points around the tunnel, the beams will cross paths. Why Was It Built? Scientists hope previously unseen particles will be discovered when the beams smash together. When Will the Experiment Happen? It has already taken two decades to get this far. Physicists may have to wait between five and 10 years before they get any significant results.