Cosmology (Edexcel GCSE Physics)

The Big Bang theory is one theory for the origin of the Universe. The Big Bang theory suggests:

• the Universe had a beginning

• the Universe is still expanding

Which of these provides evidence that the Universe had a beginning?

Evidence that the Universe is still expanding comes from observations of light from distant galaxies.

Describe how light from distant galaxies shows that the Universe is still expanding.

The Steady State theory is also a theory about the origin of the Universe.

Give one similarity and one difference when comparing the Big Bang theory with the Steady State theory.

similarity................................................................................. difference...............................................................................

Observations of the expanding Universe have shown that the further away a galaxy is from the Earth, the faster the galaxy is moving away from the Earth.

Figure 4 shows how the velocity of galaxies is related to their distance from the Earth.

Figure 4

Mpc is a unit of distance used for large distances in space.

i) Use Figure 4 to estimate the velocity of a galaxy that is 15 Mpc away from the Earth.

velocity = ............................. km/s[1]

ii) Calculate the gradient of the line shown in Figure 4.

State the unit.

gradient = ........................... unit ..........................[3]

iii) The gradient of the line in Figure 4 can be used to estimate the age of the Universe.

Explain why the gradient of the line in Figure 4 can only provide an estimate of the age of the Universe.

[2]

Which row of the table is correct for both force and velocity?

Figure 6 shows a satellite orbiting the Earth.

Figure 6

i) State the name of the force that keeps the satellite in orbit around the Earth.

[1]

ii) Draw an arrow on Figure 6 to show the direction of the force acting on the satellite, that keeps the satellite in orbit around the Earth.

Label this arrow ‘F’.

[1]

Satellites are used to gather data about the origin of the Universe.

The Big Bang theory is a theory about the origin of the Universe.

Evidence for the Big Bang theory is provided by red-shift and CMB radiation.

i) Describe what is meant by red-shift.

[2]

ii) Explain how red-shift provides evidence for the Big Bang theory.

[2]

iii) The Cosmic Background Explorer (COBE) satellite observed CMB radiation from 1989 to 1993.

State what the ‘M’ in CMB radiation stands for.

[1]

iv) State what is meant by ‘cosmic background radiation’.

[1]

v) Explain how the presence of CMB radiation provides evidence for the Big Bang theory.

[2]

Explain the term galactic redshift.

Explain why galactic redshift provides evidence to support the Big Bang theory.

Describe and explain what can be deduced from the cosmic microwave background radiation (CMBR).

Telescopes can be located on Earth or in space. 

(i) State two advantages of locating a telescope in space.

[2]

(ii) State two disadvantages of locating a telescope in space.

[2]

The Big Bang theory attempts to explain the origins of the Universe.

Describe the main ideas of the Big Bang theory.

Explain the two pieces of evidence which support the Big Bang Theory of the origin of the Universe.

State and explain the type of electromagnetic radiation the CMBR will change into over the next few billion years.

Explain why our understanding of the beginning of the Universe is just a theory.

Define the Doppler effect.

State the two properties of a wave which are observed to have changed due to the Doppler effect.

An object is moving away from a stationary observer whilst emitting a steady sound wave.  

(i) State the property of the sound wave which increases.

[1]

(ii) State the property of the sound wave which decreases.

[1]

(iii) State the property of the sound wave which remains constant.

[1]

The following passage is about the Doppler effect. 

Complete the following sentences by circling the correct words:

When a source starts to move away from / towards the observer, the wavelength of the wave broadens. 

For sound waves, sound, therefore, appears at a higher / lower frequency to the observer. 

For light waves, the light shifts towards the blue / red end of the electromagnetic spectrum due to its lower / higher frequency. 

When a source starts to move away from / towards the observer, the wavelength of the wave shortens. 

For sound waves, sound therefore appears at a higher / lower frequency to the observer. 

For light waves, the light shifts towards the blue / red end of the electromagnetic spectrum due to its lower / higher frequency. 

This is because blue / red light has a longer wavelength than blue / red light.

Stars may originate as a nebula.

i) Describe the process that then occurs to produce the conditions necessary for nuclear fusion in a new star.

[3]

ii) The energy, E, released in nuclear fusion is equivalent to loss in mass, m, according to the equation.

E = mc²

where c is the velocity of light.

c = 3.00×10⁸ m/s

In 1 second, the energy radiated by the Sun is 3.86 × 10²⁶ J.

Calculate the loss in mass of the Sun in 1 second.

loss in mass = .............................................................. kg[2]

The Big Bang theory gives an explanation for the origin of the Universe.

Explain how evidence supports the ideas that

• the Universe is expanding

• the Universe began at a single point.

A star has evolved to become a neutron star.

The mass, M, of the neutron star, of radius R, is given by

        where D is a constant

M = 4×10³⁰ kg

D = 6×10¹⁷ kg/m³

Use the equation to calculate the value for R.

R = .............................................................. m

The Big Bang theory suggests that the universe is approximately 14 billion years old.

Describe the evolution of the universe from the Big Bang until the present day. 

State the main principles of the steady state theory and explain why it is no longer used as the model representing the history of the universe.

Describe the observations of distant galaxies compared to closer galaxies and discuss what this tells us about the universe.

Figure 1 below shows the spectrum of light received on the Earth from the Sun and from a star in a distant galaxy.

Figure 1

The spectrum contains some characteristic dark lines, which occur at very specific wavelengths in the laboratory.

Explain how the shift in the position of the dark lines provides evidence to support the Big Bang theory.

The data in Figure 1, along with data from other galaxies, can be used to plot a graph showing how the shift in position changes with the distance of each galaxy from the Earth, as shown in Figure 2.

A new galaxy is discovered with a red-shift of 0.02.

Using the graph in Figure 2, estimate the distance to this new galaxy.

Show clearly how you obtained your answer.

State an assumption you made in obtaining the answer to part (b).