D.3 – Cosmology

The Hot Big Bang model is a theory that describes the origin and expansion of the universe and is supported by extensive experimental evidence.

The modern field of cosmology uses advanced experimental and observational techniques to collect data with an unprecedented degree of precision and as a result very surprising and detailed conclusions about the structure of the universe have been reached.

Understandings:

• The Big Bang model

• The cosmological principle (HL)

• Cosmic microwave background (CMB) radiation

• Fluctuations in the CMB (HL)

• Hubble’s law

• The accelerating universe and redshift (z)

• The cosmological origin of redshift (HL)

• The cosmic scale factor (R)

• Rotation curves and the mass of galaxies (HL)

• Dark matter (HL)

• Critical density (HL)

• Dark energy (HL)

Applications and skills:

• Describing both space and time as originating with the Big Bang

• Describing the characteristics of the CMB radiation

• Explaining how the CMB radiation is evidence for a Hot Big Bang

• Solving problems involving z, R and Hubble’s law

• Estimating the age of the universe by assuming a constant expansion rate

• Describing the cosmological principle and its role in models of the universe (HL)

• Describing rotation curves as evidence for dark matter (HL)

• Deriving rotational velocity from Newtonian gravitation (HL)

• Describing and interpreting the observed anisotropies in the CMB (HL)

• Deriving critical density from Newtonian gravitation (HL)

• Sketching and interpreting graphs showing the variation of the cosmic scale factor with time (HL)

• Describing qualitatively the cosmic scale factor in models with and without dark energy (HL)

International-mindedness:

• Contributions from scientists from many nations made the analysis of the cosmic microwave background radiation possible

• This is a highly collaborative field of research involving scientists from all over the world

Utilization:

• Doppler effect (see Physics sub-topic 9.5)

Aims:

• Aim 1: scientific explanation of black holes requires a heightened level of creativity

• Aim 2: unlike how it was just a few decades ago, the field of cosmology has now developed so much that cosmology has become a very exact science on the same level as the rest of physics (HL)

• Aim 9: our limit of understanding is guided by our ability to observe within our universe

• Aim 10: it is quite extraordinary that to settle the issue of the fate of the universe, cosmology, the physics of the very large, required the help of particle physics, the physics of the very small (HL)

TOK:

• Experimental facts show that the expansion of the universe is accelerating yet no one understands why. Is this an example of something that we will never know? (HL)

Essential Equations

Magnitude of the Red-Shift

Rotational velocity of star near center of galaxy

Cosmic Scale Factor (Note: CSF can also be used with Red-Shift)

Critical Density of Universe

Hubble's Law

Hubble's Law applied to Age of Universe

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