1.12 How did the Universe begin?

11 January 2011

Out of 10, how confident are you in:

Evolution theory The Big bang theory

What is a theory?

Aims

• Explore data and explanation associated with the Big Bang

Galaxies

A spiral galaxy

Two nearby galaxies

Exotic galaxies I

Exotic galaxies II

Nazirah Jetha was

brought up in Burnley.

Now she’s studying

galaxies at Birmingham

University.

Galaxies, galaxies, galaxies

Pedro Ferreira is a

scientist at the University

of Oxford. He’s trying to

find out more about how

the Universe began.

Pedro Ferreira tries out his ideas by checking

predictions against observations, and also by using

computer simulations or ‘models’ like this. It shows

how galaxies are spread across the Universe.

Joy McKenny is an

experimental scientist.

She develops special

mirrors for observing

radiation from distant

objects in space.

A big bang

• Until the 20th century most people thought the Universe was eternal and unchanging

• Big telescopes changed everything, light from distant galaxies showed the Universe was getting bigger

• Space itself is actually expanding

• It is now imagined that the Universe was once incredibly dense, hot and small – the Big Bang theory

The bigger bang

• The theory passed a major test in 1965. A group of scientists predicted that the afterglow of the Big Bang should still fill the whole universe

• Penzias and Wilson found an annoying background hiss on their radio antennae – they found the microwave background radiation

• Whenever you see the snow on an untuned tv channel, some of the signal is this afterglow

The age of the Universe

• Fifty years ago scientists used the speed and distance of galaxies to estimate how long ago all galaxies were in the same place

• They made lots of assumption meaning the age of the Universe was between 10 – 20 billions years

• Later observations (2003) clarifies this date to 13.7 billion years +/- 0.2 by

Other evidence:

• Hot big bang explains the ratio of hydrogen to helium

• The oldest stars are younger than the Universe (rather important!)

Models of the Universe

• Cosmology is the study of the cosmos or universe

• Cosmologists often use mathematics to help their thinking

• Computer models use maths to stimulate the formation of galaxies

• Topology models physical properties