The Big Bang theory connects particle physics to the birth of our universe. It explains how fundamental forces separated and particles formed in the first moments after creation. This cosmic drama set the stage for everything we see today.

Exploring the Big Bang helps us understand dark matter, cosmic radiation, and why there's more matter than antimatter. It's a cosmic detective story, using particle physics to decode the universe's earliest secrets and greatest mysteries.

Particle Physics and the Early Universe

High-Energy Conditions and Fundamental Interactions

• Early universe characterized by extremely high energies and temperatures provided conditions for fundamental particle interactions unreplicable in modern experiments
• Particle physics theories (Standard Model) provide framework for understanding matter and energy behavior in extreme early universe conditions
• Study of particle physics informs understanding of processes leading to formation of matter and fundamental forces in universe
• Cosmological models of early universe rely on particle physics to explain phenomena (baryogenesis, nucleosynthesis, cosmic microwave background formation)

Symmetry Breaking and Phase Transitions

• Concept of spontaneous symmetry breaking in particle physics crucial for understanding phase transitions in early universe (electroweak phase transition)
• Particle physics predicts existence of dark matter particles playing significant role in evolution of large-scale structures in universe

Timeline of the Big Bang

Early Epochs and Force Separation

• Big Bang timeline begins with Planck epoch ($10^{-43}$ seconds after Big Bang) where quantum gravity effects dominate and current physics theories break down
• Grand Unification epoch ($10^{-43}$ to $10^{-36}$ seconds) marks separation of strong nuclear force from electroweak force, first symmetry breaking event
• Electroweak epoch ($10^{-36}$ to $10^{-12}$ seconds) characterized by separation of electromagnetic and weak nuclear forces, and inflationary period of rapid expansion

Particle Formation and Nucleosynthesis

• Quark epoch ($10^{-12}$ to $10^{-6}$ seconds) sees quark confinement leading to formation of hadrons (protons, neutrons)
• Lepton epoch ($10^{-6}$ to 1 second) dominated by leptons and anti-leptons, with most hadrons and anti-hadrons having annihilated
• Photon epoch (1 second to 380,000 years) begins nucleosynthesis, forming first atomic nuclei (hydrogen, helium)
• Recombination epoch (380,000 years) marks formation of neutral atoms and decoupling of matter and radiation, allowing cosmic microwave background to form

Evidence for the Big Bang

Elemental Abundance and Cosmic Radiation

• Abundance of light elements in universe (hydrogen, helium, lithium) aligns with predictions from Big Bang nucleosynthesis, supporting theory's accuracy in describing early particle interactions
• Cosmic microwave background radiation exhibits near-perfect blackbody spectrum consistent with particle physics models of early universe
• Observed matter-antimatter asymmetry in universe supports theories of baryogenesis involving CP violation in particle interactions during early universe

Particle Discoveries and Cosmic Neutrinos

• Discovery of Higgs boson provides evidence for Higgs mechanism crucial for understanding mass generation in early universe
• Neutrino physics supports Big Bang predictions and informs models of early universe particle interactions
  • Detection of cosmic neutrino background
  • Observation of neutrino oscillations
• Success of inflationary models in explaining cosmic uniformity and flatness relies on concepts from particle physics (scalar fields, vacuum energy)

Standard Model Limitations

Unaccounted Phenomena and Particles

• Standard Model does not account for gravity becoming increasingly important at extreme energies of early universe (Planck epoch)
• Dark matter not explained by Standard Model requires extensions or new theories to describe its nature and interactions
• Observed matter-antimatter asymmetry in universe not fully explained by CP violation within Standard Model necessitates additional mechanisms or new physics

Cosmological Challenges and Particle Masses

• Inflation requires physics beyond Standard Model to explain rapid expansion and subsequent reheating of universe
• Standard Model provides no mechanism for generating neutrino masses known to be non-zero from neutrino oscillation experiments and playing role in early universe physics
• Hierarchy problem questions why weak force much stronger than gravity becomes particularly relevant when considering physics of early universe
• Standard Model does not explain nature of dark energy playing crucial role in expansion of universe and potentially having implications for early universe physics