Introduction to Cosmology

Modern cosmology has entered its most precise — and most contested — era. Satellites have measured the universe's age, geometry, and composition to within a percent. Yet the two best methods for measuring how fast it's expanding now disagree by enough that something has to give: the Hubble tension. Introduction to Cosmology takes readers through the full architecture of this science, from Einstein's field equations and the Friedmann equations that govern cosmic expansion, through dark matter, the cosmic microwave background, and Big Bang nucleosynthesis, to inflation, structure formation, dark energy, and the still-unsolved question of why the universe contains matter at all.

What sets this book apart is depth of practice and currency of data. Every major derivation is followed by a fully worked example — 863 of them across sixteen chapters — turning abstract field equations into calculations a reader can actually perform. Over 100 figures, including real photography of the instruments and observatories behind the data, ground the mathematics in the actual observational campaigns that produced it. And unlike most textbooks on this shelf, it's current through DESI's 2025 dark energy results, JWST-era galaxy discoveries, and 2023 laboratory constraints on the origin of matter — a snapshot of cosmology as it stands today, not a decade ago.

• The Robertson–Walker metric derived directly from the cosmological principle, and the Friedmann equations built from it
• Zwicky's 1933 galaxy-cluster mass discrepancy, Vera Rubin's rotation-curve evidence, and the Bullet Cluster's direct proof that dark matter is real and separable from ordinary gas
• The cosmic microwave background's acoustic peaks, the Planck/WMAP/COBE measurements, and what the CMB's polarization and lensing signal reveal about neutrino mass
• Neutron-proton freeze-out, the deuterium bottleneck, and why the primordial helium-4 abundance still constrains the number of neutrino species
• The horizon, flatness, and monopole problems, and how slow-roll inflation solves all three — plus reheating and the swampland objections string theorists have raised against it
• Structure formation from primordial fluctuations through the matter power spectrum, redshift-space distortions, and the missing-satellites problem
• The 1998 supernova discovery of cosmic acceleration, the cosmological-constant problem (the "worst prediction in physics"), and quintessence as a dynamical alternative
• The Hubble tension worked from both sides — Cepheid/supernova distance-ladder measurements versus the CMB-inferred value — along with the S8 tension and DESI's 2024–2025 evolving-dark-energy hints
• Sakharov's three conditions for baryogenesis, electroweak and leptogenesis mechanisms, and the 2023 electron-EDM limits that are actively ruling out candidate models
• Gravity Probe B's direct measurement of frame-dragging, and the historical arc from Mercury's anomalous perihelion to LIGO's 2015 gravitational-wave detection
• Real observational instruments throughout — Hooker and Hale telescopes, COBE/WMAP/Planck, JWST, DESI — shown alongside the data they produced

• 863 worked examples — far more calculation practice than a typical end-of-chapter problem set
• Updated through DESI DR2 (2025), JWST-era observations, and 2023 electron EDM constraints
• 108 figures, including real observatory and instrument photography alongside technical diagrams
• Devotes full chapters to open, unresolved problems (the Hubble tension, baryogenesis) rather than treating cosmology as a closed subject
• Builds physical intuition alongside the mathematics, not equations in isolation