# Origins of the Universe and How It is Changing

In this worksheet, students will explore theories about the creation of the Universe and the red-shift (how the Universe is changing).

Key stage:  KS 4

Curriculum topic:  Physics: Space Physics

Curriculum subtopic:  Features of the Solar System

Difficulty level:

### QUESTION 1 of 10

Around 15 billion years ago all of the matter in the Universe was one single point. Imagine how compacted everything was! The temperature in that single point was more than one trillions degrees Celsius, literally hotter than anything there has ever been or ever will be. Nobody is yet sure why or how that single point exploded, and the Universe took a form similar to how we know it today. It all happened in a small fraction of a second and we call this explosion the Big Bang

After one-ten-millionth of a second, the temperature dropped to one billion degrees Celsius, what a relief! In one second there were electrons, protons and neutrons and after three seconds hydrogen and helium were formed.

The estimated mass of the Universe is 3 x1052 kg. That means you have to multiply 3 by 10 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000! Not a small mass indeed! How could it fit into that small point? The density was really high.

Scientists have found that the Universe is expanding, which means galaxies are moving away from each other. There is a theory stating that the Universe will reach a maximum size and will then start collapsing, returning to the original small point; this is called the Big Crunch. In order to demonstrate the expanding Universe, you can draw dots on a balloon to represent galaxies and then blow it. The bigger the balloon gets, the faster the dots will move away from each other.

Scientists have come to the conclusion that the Universe is expanding due to redshift. Red shift is difficult to understand, so pay close attention:

The Earth constantly receives signals from all parts of the Universe. The spectrum of white light we receive from the Sun is shown in the diagram as unshifted. Watch the white vertical lines. On the redshifted spectrum of the diagram the white lines are the same distance apart, but have shifted towards the red end. This is light from a distant star and the redshift means it is moving away from us. The opposite happens with blue shift.

To understand red shift a bit better, recall the last time you heard an ambulance or police siren. As it was approaching you the sound was higher pitched than when it was moving away from you, but the sound the siren made was actually the same. It was just that you could hear a different pitch sound depending on its distance from you.

Where was all matter of the Universe before the big explosion?

At a number of locations

In a single point

In the distant galaxies

What is the name of the expansion that gave the Universe a form that we can recognise today?

The Big Explosion

The Big Pop

The Big Bang

How many seconds did it take for hydrogen and helium to form?

2 seconds

3 seconds

6 seconds

Select one of the words below to complete the following sentence:

The density in that single point before the Big Bang was ________.

High

Low

Describe the theory that exists for the movement of the Universe today.

It is collapsing

It is stable

It is expanding

What can you use to demonstrate the expanding Universe?

A balloon

A sponge

A football

What statement describes the Big Crunch theory?

The Universe is expanding.

The Universe has exploded from a single point.

The Universe will reach its maximum size and will then gradually collapse to a single point.

What is the opposite of redshift?

Purple shift

Blue shift

Green shift

What do scientists compare in order to understand the movement of the Universe?

Light from nearby stars

Light from distant stars

Light from the Sun and light from distant stars

What do you need to look at on a light spectrum to detect redshift?

The colours of the spectrum

The red end

The lines

• Question 1

Where was all matter of the Universe before the big explosion?

In a single point
EDDIE SAYS
All matter of the Universe before the big expansion was in a single point. It wasn't really matter as we know it, but more like energy - it gets weird when you push everything together like that...
• Question 2

What is the name of the expansion that gave the Universe a form that we can recognise today?

The Big Bang
EDDIE SAYS
The Big Bang is an explosion that released all the matter in the Universe from one single point to start shaping up to what we know it to be today. It wasn't an explosion, but more of a 'rapid expansion'.
• Question 3

How many seconds did it take for hydrogen and helium to form?

3 seconds
EDDIE SAYS
Hydrogen and helium were formed 3 seconds after the Big Bang took place. They needed to wait for the universe to cool down so they could from.
• Question 4

Select one of the words below to complete the following sentence:

The density in that single point before the Big Bang was ________.

High
EDDIE SAYS
The density in that single point before the Big Bang was high. Again, because it was literally everything in the universe compressed into a single point, things get strange, it wasn't really matter as we know it now.
• Question 5

Describe the theory that exists for the movement of the Universe today.

It is expanding
EDDIE SAYS
Scientists today believe that the Universe is expanding. We know this because of the evidence we get when we are looking at starts from far away.
• Question 6

What can you use to demonstrate the expanding Universe?

A balloon
EDDIE SAYS
A balloon can be used to demonstrate the expanding Universe, by drawing dots on it before it is blown up, and then blowing up the balloon and watching the dots move away from eachother.
• Question 7

What statement describes the Big Crunch theory?

The Universe will reach its maximum size and will then gradually collapse to a single point.
EDDIE SAYS
The theory behind the Big Crunch is that the Universe will, at some point, reach its maximum size and will then gradually collapse to a single point again. This is what we think will happen given the evidence we currently have. But we don't really understand the universe very well and there are still a lot of pieces missing in the puzzle.
• Question 8

What is the opposite of redshift?

Blue shift
EDDIE SAYS
The opposite of redshift is blue shift. Redshift happens when things move away from you and blue shift happens when things move towards you.
• Question 9

What do scientists compare in order to understand the movement of the Universe?

Light from the Sun and light from distant stars
EDDIE SAYS
In order to understand how the Universe moves scientists compare light from the Sun and light from distant stars.
• Question 10

What do you need to look at on a light spectrum to detect redshift?

The lines
EDDIE SAYS
In order to detect redshift one has to look at the position of the lines on the light spectrum. When we compare them with what we know they should look like we can see that they have moved. This tells us that the star is moving away from or towards us.
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