The Expanding Universe
PHYS 501 · Module 5
This module introduces the observational basis of modern cosmology. Students study Hubble's law, redshift, distance measurements, the cosmic microwave background, and dark energy.
Lessons in this module
Hubble's law and the expanding universe
Distant galaxies recede from us with speeds proportional to distance. This lesson explains Hubble's law, expansion of space, scale factor, and the meaning of the Hubble constant.
Redshift and distance measurements
Cosmology depends on measuring redshifts and distances. This lesson explains redshift definitions, standard candles, distance ladders, luminosity distance, and lookback time.
The cosmic microwave background
The cosmic microwave background is relic radiation from the early universe. This lesson explains recombination, blackbody radiation, anisotropies, and why the CMB is a cornerstone of cosmology.
Dark energy and the accelerating expansion
Observations show that cosmic expansion is accelerating. This lesson introduces Type Ia supernova evidence, the cosmological constant, equation of state, and open questions about dark energy.
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