Physics:
The Universe
1 SPEAKING Work in pairs. How many stars, planets or galaxies can you name? Write a list.
2 Read the text. What do these very large numbers refer to?
What is the universe?
The universe contains everything we know about, including all living things, stars, planets, space, energy and even time. It is bigger that we can possibly imagine. It contains billions of galaxies (groups of stars held together by gravity), and each galaxy can also contain billions of stars. Distances in space are enormous. Because of this, we measure them using ‘light years’, the distance that light travels in one year.
The Big Bang theory
Many scientists think that the universe began about 13.8 billion years ago, with what they call the ‘Big Bang’. Before that time, they believe that the whole universe was in a space smaller than the end of a ! The Big Bang was when it suddenly expanded. The famous scientist Einstein showed that the universe is still getting bigger today.
From atoms to stars
Energy from the Big Bang created the elements and . After millions of years, gravity pulled these gases together and eventually formed stars. Then other elements formed in these stars. It is amazing to think that everything we can see (including our own bodies!) comes from the stars.
Our place in the universe
Do you feel small? You should! We may think the Earth is important, but there are billions more planets just in our own galaxy, the Milky Way. It is around 100,000 light years from one side of our galaxy to the other, and 2.5 million light years to the next closest galaxy, Andromeda.
Will the universe end?
Scientists think the universe may end, but not for billions or even trillions of years. One theory, often called the ‘Big Freeze’, is that heat from the hot parts of the universe will eventually spread into the cooler parts until the temperature is the same everywhere. The universe cannot live if this happens. Another theory, the ‘Big Crunch’, is that the universe will get smaller and smaller and become hotter and until it goes back to the way it was before the Big Bang.
3 Rewrite these sentences so that they are true.
4 SPEAKING Work in pairs. Do you think there could be life in other parts of the universe? Do you think it would be a good thing if there is? Give your reasons.
