OCR · GCSE · Physics
Course version: J249 · Version from Sept 2018
Explain how red shift and other evidence can be linked to the Big-Bang…
Full specification wording
Beyond Earth: explain how red shift and other evidence can be linked to the Big-Bang model (to include: CMBR) (content found only in the physics separate science qualification)
The Big-Bang model says the universe began from a very small, hot, dense region and has expanded ever since.
Checked against the OCR J249 specification (opens in a new tab) on .
- Point 2 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The Big-Bang model says the universe began from a very small, hot, dense region and has expanded ever since. Red-shift supports this because nearly all galaxies show light shifted to longer wavelengths, indicating they recede, and more distant galaxies recede faster, which fits expansion from a common origin. A second line of evidence is the cosmic microwave background radiation (CMBR): faint microwave radiation arriving from every direction, interpreted as cooled remnant radiation from the early hot universe. Together these observations are explained by an initial hot dense state followed by expansion and cooling. A useful method is to state each piece of evidence, then say what the Big-Bang model predicts and how the observation matches that prediction.
What earns the marks
- States that the Big-Bang model describes the universe expanding from an initial hot, dense state.
- Explains that the red-shift of light from receding galaxies supports expansion from a common origin.
- Describes the CMBR as faint microwave radiation coming from all directions, interpreted as remnant radiation from the early universe.
- Links the cooling of the early universe to the present low temperature of the CMBR as evidence for the model.
Common mistakes and how to put them right
Presents the Big-Bang model as an explosion of matter into empty space.
Put it right by describing expansion of space itself from a hot dense state.
Describes the CMBR as light from stars or galaxies.
Put it right by identifying it as faint microwave radiation filling all of space.
Claims red-shift alone proves the model with certainty.
Put it right by saying the evidence supports or is consistent with the model.
Omits the cooling of the universe when explaining the CMBR.
Put it right by linking the early hot state to the present low-temperature microwaves.
Exam tips
- Name CMBR in full at least once and state that it is microwave radiation.
- Give at least two distinct pieces of evidence and say how each supports the model.
- Use the phrase 'consistent with' or 'supports' rather than claiming proof.
Try the lesson
The start of the Beyond Earth: explain how red shift and other evidence can be linked to the Big-Bang model (to include: CMBR) (content found only in the physics separate science qualification) lesson, made from checked teaching notes for this specification point.
Have a go first
A spectral line that has a wavelength of 500 nm in the laboratory is measured at 510 nm in light from a distant galaxy. What has happened to the light?
Listen
The Big-Bang model says the universe began from a very small, hot, dense region and has expanded ever since. Red-shift supports this because nearly all galaxies show light shifted to longer wavelengths, indicating they recede, and more distant galaxies recede faster, which fits expansion from a common origin. A second line of evidence is the cosmic microwave background radiation (CMBR): faint microwave radiation arriving from every direction, interpreted as cooled remnant radiation from the early hot universe. Together these observations are explained by an initial hot dense state followed by expansion and cooling. A useful method is to state each piece of evidence, then say what the Big-Bang model predicts and how the observation matches that prediction. A strong answer earns marks for these points. States that the Big-Bang model describes the universe expanding from an initial hot, dense state. Explains that the red-shift of light from receding galaxies supports expansion from a common origin. Describes the CMBR as faint microwave radiation coming from all directions, interpreted as remnant radiation from the early universe. Links the cooling of the early universe to the present low temperature of the CMBR as evidence for the model. A common slip: Presents the Big-Bang model as an explosion of matter into empty space. Instead, describing expansion of space itself from a hot dense state. Exam tip: Name CMBR in full at least once and state that it is microwave radiation.
Key words
Say what each word means before you turn the card.
Big-Bang model
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Red-shift as supporting evidence
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Cosmic microwave background radiation
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Expansion and cooling of the universe
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See every definition
- Big-Bang model
- The universe began from a very small, hot, dense region and has expanded ever since.
- Red-shift as supporting evidence
- Nearly all galaxies show light shifted to longer wavelengths, indicating they recede, and more distant galaxies recede faster, which fits expansion from a common origin.
- Cosmic microwave background radiation
- Faint microwave radiation arriving from every direction, interpreted as cooled remnant radiation from the early hot universe.
- Expansion and cooling of the universe
- An initial hot dense state followed by expansion and cooling, which together explain the observations.
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Test your understanding of Beyond Earth: explain how red shift and other evidence can be linked to the Big-Bang model (to include: CMBR) (content found only in the physics separate science qualification)
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