By: Lidia Moscoso, Lucia Vicario, Tania Martin and Paula Moreno THE BIG BANG THEORY

WHAT IS THE BIG BANG THEORY? The Big Bang was a theory proposed by Albert Einstein. Astronomers believe that the Universe came into being about 13.7 billion years ago, in an explosion known as the Big Bang. In an instant, space and the building blocks of matter were created, and time began. Initially the Universe would have been extremely hot and dense. From that moment on, the Universe began to expand, and continues to cool off till today. Over billions of years, matter formed into large and complex structures that continue to evolve.

FACTS This theory was born from the observation that other galaxies are moving away from our own at great speed and in all directions. The Big Bang created an extremely hot Universe. It started to cool off and expand, for a brief moment growing at a tremendous rate. In less than a millisecond, the first matter was created But, for thousands of years, the Universe was dominated by radiation. It includes Albert Einstein's general theory of relativity along with standard theories of fundamental particles.

EVIDENCE FOR THE BIG BANG Redshift of Galaxies Microwave Background Mixture of Elements The look back in time

REDSHIFT OF GALAXIES Galaxies appear to be moving away from us at speeds proportional to their distance Means that the Universe is probably expanding. Supports the expansion of the universe and suggests that the universe was once compacted.

COSMIC MICROWAVE BACKGROUND Electronic radiation from the sky with no source recognizable It is the thermal radiation left over from the time of recombination in Big Bang Cosmology. It is fundamental to observational cosmology because it is the oldest light in the universe.

MIXTURE OF ELEMENTS The Big Bang theory predicts how much of each element should have been made in the early universe. You cannot look in new stars, like the Sun, for this evidence, because they contain elements that were created in previous generations of stars. As such, the composition of new stars will be very different from the composition of stars that existed 7 billion years ago, shortly after the Big Bang.

LOOKING BACK IN TIME Main alternative to the Big Bang theory: Steady State theory. Remember that because light takes a long time to travel across the Universe, when we look at very distant galaxies, we are also looking back in time.