Text c The Evolution of the Universe

Task. Scan the text and compare the “open” and “closed universe” theories.

In recent years some exciting hypotheses have been advanced about the origin and evolution of the universe. Most scientists have by now accepted what is called the “big bang” theory. About 18 billion years ago, they say, a primordial fireball exploded and immediately began to expand, until eventually clouds of gas and dust formed and condensed, coalescing into galaxies of stars. It has been estimated that the universe now consists of about 100 billion galaxies, each one with about. 100 billion stars, all rushing away from each other as the universe continues to expand.

Our galaxy, the Milky Way, began to form about 10,000 million years ago as an enormous flattened spiral consisting of dust, gas and stars. The spiral is thicker at the centre, where the stars are more crowded. About 4,500 million years back, near the edge of the galaxy, the solar system came into being. Some of the nuclei in a cloud of gas and dust condensed, and as they were rotating they gathered up surrounding matter, growing ever larger and more solid. The central nucleus became the sun and the others developed into the planets in the solar system, one of them being our own planet, Earth. The earth began as a mass of liquid fire, but after cooling sufficiently, the surface solidified to form a rocky crust, and clouds condensed as rain, forming seas. The crust, however, has remained a thin layer, in places only a few kilometres thick. Under it lies a thicker layer of hotter denser rocks called the mantle, while the temperature of the still partially molten inner core has been calculated by some scientists to be as much as 5,538 degrees centigrade. The crust, more over, has been continuing to contract and shift, slowly changing the landscapes of the earth.

The story of the universe so far is thus one of continuous expansion and evolution. Some scientists believe that this process will continue for ever. According to the “open universe” theory, the universe will continue to expand indefinitely, because it doesn’t contain enough matter to control the fleeing galaxies by gravitational attraction. On the other hand, according to the “closed universe” theory, the universe will eventually contract, because the gravitational force is supported by matter in stars and gas clouds that has not yet been detected. Astronomers have already discovered individual instances of this kind of contraction in what they call “black holes”; these are collapsed stars, which suck in all surrounding matter into a mass of infinitesimal volume but with immense gravity. If there had not been enough surrounding matter, black holes could not have operated in this way. Thus, it is argued, the whole universe may eventually contract into an incredibly dense cluster about 100 billion years from now. Will the universe simply cease to exist, or will it expand again into its present form or into a completely different form?

Ex. 1. Put the sentences in the logical order.

1. Our galaxy, a huge spiral-shaped collection of stars, formed 10 billion years ago.

2. The gravitational pull of the unknown matter will prevent the Universe from growing beyond a certain size.

3. The universe was born in unimaginable explosion 18 billion years ago.

4. As the earth was cooling a rocky crust was forming and ocean came into existence.

5. The universe is continuously expanding and evolving, and it will expand forever.

6. The spiral arms of the galaxies are where star birth is taking place.

7. The earth began as a mass of liquid fire.

8. The universe had a definite beginning. Will it then have a definite end?

Ex. 2. Complete the chart below.

Theory	Pros	Cons	Further Development of the Universe

Ex. 3. Discuss in groups the problem raised in the text.