Activity type Activity 1.6 The Big Bang

About 14 billion years SEVERAL IMPORTANT ago, a huge explosion OBSERVATIONS SUPPORT THE started the expansion BIG BANG MODEL. of the universe. At that time, all the matter and THE EXPANSION OF THE UNIVERSE energy of space was Edwin Hubble's observation of the red cloud of du contained at one point, a is a st and g shift in the spectra of distant galaxies bul as fr . ne om ve from which particles A whic vol was the first clue the theory might be h stars ets e moved away from each and plan right. other, at high speed, in THE ABUNDANCE OF LIGHT ELEMENTS every direction. The Big HYDROGEN, HELIUM AND LITHIUM Bang was actually an How was the universe The amounts of these elements present explosion of space. created? People once believed it in the observable universe, agree with Since then, the universe had no beginning or end and was the predictions in the Big Bang theory. has been continuously truly infinite. These light elements should have been expanding and so The Big Bang theory proposed the fused from protons and neutrons in the there is more and more universe was created about first few minutes after the Big Bang. distance between 14 billion years ago. It has a history, COSMIC MICROWAVE BACKGROUND clusters of galaxies. a beginning and is immense, but finite. RADIATION (CMB) The early universe should have been very hot. The cosmic microwave background radiation is the remnant heat leftover The Cosmic from the Big Bang. Background Explorer (COBE) is a satellite launched DID YOU KNOW? in 1989 to measure the infrared and Sir Fred Hoyle, an eminent astronomer of the cosmic microwave Sir Fred Hoyle 20th Century, coined the term "Big Bang" to background ridicule the theory of an expanding universe. Thermal photograph of cosmic background radiation radiation from the taken from the COBE. Hotter areas appear red. early universe.

Science Futures Student Guide Part 1 Last frontiers for scientific discovery 13 Activity 1.6 The big bang Continued

1 billion yrs. 15 billion yrs. -200 ºC -273 ºC As galaxies cluster 300,000 yrs. Gravity makes ,000 ºC 7together under 10 6hydrogen and gravity, the first stars helium gas coalesce Electrons combine die and spew heavy to form the giant 3 min. with protons to elements into space: 5 clouds that will 8 ºC form atoms, mostly these will eventually become galaxies: 10 hydrogen and helium. form into new stars smaller clumps of gas Still too hot to Light can finally shine. and planets. -6 collapse to form the 10 -43 sec. form into atoms, sec. 10 4 first stars. 13 ºC charged electrons -32 10 and protons prevent 10 sec. Time A rapidly cooling light from shining, the IT TOOK ABOUT A BILLION 27 Temperature 10 ºC cosmos permits universe is a superhot YEARS FOR THE COOLING 3 fog. The cosmos quarks to clump PRODUCTS OF THE BIG Post-inflation, into protons and 1goes through the universe is a BANG TO BEGIN TO FORM a superfast 2 neutrons. seething hot soup THE GIANT CLOUDS “inflation,” of electrons, quarks expanding from and other particles. THAT WOULD CONDENSE the size of an TO BECOME GALAXIES, atom to that of a grapefruit in a STARS AND PLANETS. tiny fraction of a second. Click here to learn more about the Big Bang.

Science Futures Student Guide Part 1 Last frontiers for scientific discovery 14