6.2.3 The Universe
- Syllabus
- 0625–2026–2027
- Topic
- 6.2.3
- Level
- —
6.2.3.1—Milky Way is one of many billions of
- Know: the Milky Way is one of many billions of galaxies making up the Universe and that the diameter of the Milky Way is approximately 100 000 light-years
6.2.3.2—Redshift as an increase in the
- Describe redshift as an increase in the observed wavelength of electromagnetic radiation emitted from receding stars and galaxies
6.2.3.3—Light emitted from distant galaxies
- Know: the light emitted from distant galaxies appears redshifted in comparison with light emitted on the Earth
6.2.3.4—Redshift in the light from distant
- Know: redshift in the light from distant galaxies is evidence that the Universe is expanding and supports the Big Bang Theory
6.2.3.5—Microwave radiation of a specific
- Know: microwave radiation of a specific frequency is observed at all points in space around us and is known as cosmic microwave background radiation (CMBR)
6.2.3.6—The CMBR was produced shortly after
- Explain that the CMBR was produced shortly after the Universe was formed and that this radiation has been expanded into the microwave region of the electromagnetic spectrum as the Universe expanded
6.2.3.7—Speed v at which a galaxy is moving
- Know: the speed v at which a galaxy is moving away from the Earth can be found from the change in wavelength of the galaxy’s starlight due to redshift
6.2.3.8—Distance d of a far galaxy can be
- Know: the distance d of a far galaxy can be determined using the brightness of a supernova in that galaxy
6.2.3.9—Hubble constant H0 as recession speed
- Define Hubble constant H0 as recession speed divided by distance from Earth; recall/use: H0 = v/d
6.2.3.10—Current estimate for H0 is 2.2 × 10–18
- Know: the current estimate for H0 is 2.2 × 10–18 per second
6.2.3.11—D/v = 1/H0 estimates the age of the
- Know d/v = 1/H0 estimates the age of the Universe and supports the idea that all matter was once at a single point
Objective notes
11 learning objectivesConceptIGCSE Physics