Final Exam

Great! I’ve pulled everything from your exam study guide and will now give you a detailed, complete set of flashcards that cover EVERY key topic and concept.

Here’s the full flashcard set organized by section:

🌌 General Relativity

✅ What is the key idea of general relativity (GR)?
→ The universe is four-dimensional spacetime; only spacetime separation is absolute.

✅ What are the two postulates of GR?
→ 1⃣ Laws of physics are the same in all reference frames.
2⃣ Gravity is the curvature of spacetime caused by mass and energy.

✅ What experimental evidence supports GR?
→ Gravitational lensing, precession of Mercury’s orbit, gravitational redshift, GPS corrections.

✅ What is the cosmological principle?
→ The universe is homogeneous and isotropic on large scales.

✅ Why is the universe expanding but galaxies aren’t?
→ Spacetime itself expands, but galaxies are bound by gravity.

✅ What is a black hole?
→ A region where gravity is so strong that not even light can escape.

✅ How can a black hole form?
→ When a massive star collapses under its own gravity.

✅ How do we observe black holes?
→ By detecting X-rays from matter falling in or observing effects on nearby stars.

🔥 Cosmological Nuclear Physics

✅ What is the cosmic elemental abundance?
→ ~75% hydrogen, ~25% helium, <1% everything else.

✅ How does the universe’s temperature change as it expands?
→ Temperature and energy density decrease as the universe expands.

✅ What happens to atoms/nuclei when heated?
→ They break apart into constituent particles.

✅ When did particle, nuclear, and atomic physics dominate?
→ Particle: first microseconds; nuclear: first few minutes; atomic: after ~380,000 years.

✅ What are alpha, beta, gamma radiation?
→ Alpha: helium nuclei, beta: electrons/positrons, gamma: photons; gamma is most dangerous.

✅ How big is an atom vs. nucleus?
→ Atom: ~10⁻¹⁰ m; nucleus: ~10⁻¹⁵ m.

✅ How do a cloud chamber and Geiger counter detect radiation?
→ Cloud chamber: visible tracks; Geiger counter: counts ionizing events.

✅ What is the electric force law?
→ F=kq1q2r2.

✅ What is an isotope?
→ Same protons, different neutrons.

✅ How to find protons, neutrons, electrons?
→ Atomic number = protons = electrons; neutrons = mass number - atomic number.

✅ What’s half-life?
→ Time for half of a radioactive sample to decay.

✅ How old is the Earth? Universe?
→ Earth: ~4.5 billion years; Universe: ~13.8 billion years.

✅ What binds a nucleus?
→ The strong nuclear force.

✅ Difference between fission and fusion?
→ Fission: splitting heavy nuclei; fusion: combining light nuclei.

✅ Elements used in fission and fusion?
→ Fission: uranium, plutonium; fusion: hydrogen, deuterium, tritium.

✅ What’s a chain reaction?
→ Released neutrons cause further fissions.

✅ Applications of fission/fusion?
→ Nuclear power, bombs, medical treatments.

✅ How did the expanding universe produce hydrogen/helium?
→ Primordial nucleosynthesis during the first few minutes.

💥 Big Bang vs. Steady State Cosmology

✅ What’s the difference?
→ Big Bang: universe had a beginning; Steady State: eternal, constant density.

✅ Predictions on galaxy ages?
→ Big Bang: galaxies age over time; Steady State: all ages distributed evenly.

✅ What’s recombination?
→ Time when electrons and nuclei combined; universe became transparent.

✅ How were heavier elements created?
→ Stellar nucleosynthesis inside stars.

✅ How do stars form?
→ Gas clouds collapse under gravity.

✅ How does mass affect a star’s fate?
→ Low mass → white dwarf; medium mass → red giant, white dwarf; high mass → supernova, neutron star, black hole.

✅ What are a protostar, brown dwarf, red giant, white dwarf, supernova, neutron star, pulsar?
→ Protostar: forming star; brown dwarf: failed star; red giant: expanded aging star; white dwarf: collapsed core; supernova: exploding star; neutron star: collapsed dense core; pulsar: rotating neutron star emitting beams.

✅ How are supernovae used to measure expansion?
→ As standard candles to measure distance and acceleration.

✅ What’s equilibrium radiation?
→ Radiation where energy in = energy out; CMB is an example.

✅ Who predicted and discovered the CMB?
→ Predicted by Gamow, Alpher, Herman; discovered by Penzias and Wilson; shown to be equilibrium by COBE satellite.

⚛ Quantum Mechanics

✅ What’s wave-particle duality?
→ Particles behave as both waves and particles.

✅ What’s the two-slit experiment?
→ Shows interference pattern, proving wave-like behavior.

✅ What’s the wave function?
→ Describes probability of a particle’s position or momentum.

✅ Who contributed to quantum mechanics?
→ Bohr: atomic model; Heisenberg: uncertainty; Schrödinger: wave equation; Pauli: exclusion principle; Dirac: antimatter.

✅ How does wave-particle duality explain atomic energy levels?
→ Only certain standing wave patterns allowed → quantized levels.

✅ How does Pauli exclusion explain orbitals and supernovae?
→ No two fermions can occupy same state → degeneracy pressure resists collapse.

✅ What’s antimatter?
→ Particles with opposite charge to normal matter.

✅ What happens when matter meets antimatter?
→ Annihilation, releasing energy.

🔬 Particle Physics

✅ What are protons and neutrons made of?
→ Quarks.

✅ How do we study small scales?
→ Use high-energy particle beams.

✅ Size of quarks and nucleons?
→ Quark: ~10⁻¹⁸ m; nucleon: ~10⁻¹⁵ m.

✅ How does a particle accelerator work?
→ Uses electromagnetic fields to accelerate particles.

✅ What are the fundamental particles?
→ Quarks and electrons.

✅ How do particles interact at quantum level?
→ Via force-carrying particles (messenger particles).

✅ What are the four forces and their messengers?
→ Strong (gluons), electromagnetic (photons), weak (W/Z bosons), gravity (gravitons, hypothesized).

✅ Why doesn’t electron fall into nucleus?
→ Strong force only acts on quarks, not electrons.

✅ What’s antimatter made of?
→ Anti-quarks, anti-electrons (positrons), anti-protons, etc.

✅ How do matter-antimatter collisions create heavy particles?
→ Energy converts to mass via E=mc2.

✅ How were heavier quarks and leptons discovered?
→ By colliding matter and antimatter at high energy.

✅ What are the six quarks and six leptons?
→ Quarks: up, down, charm, strange, top, bottom; leptons: electron, muon, tau + their neutrinos.

✅ What’s the strong force’s behavior with distance?
→ Increases with separation → quark confinement.

✅ What’s the Higgs Field?
→ Field giving mass to particles.

✅ What’s the Higgs Boson?
→ Particle associated with the Higgs Field.

⏳ The First Few Seconds & Inflation

✅ What’s an event horizon?
→ Boundary beyond which events cannot affect an observer.

✅ What’s the horizon problem?
→ We see ~100,000 causally disconnected regions with similar properties.

✅ Why is a flat universe unnatural?
→ Small deviations would grow over time; fine-tuning required.

✅ What’s inflation?
→ Rapid expansion in early universe solving horizon and flatness problems.

✅ Predictions of inflation?
→ Flat universe, homogeneity, primordial density fluctuations.

✅ What’s a gravity wave?
→ Ripples in spacetime from accelerating masses.

✅ When were gravity waves first detected?
→ 2015 by LIGO.

✅ How would primordial gravity waves prove inflation?
→ By polarizing the cosmic microwave background.

🌑 Dark Matter

✅ What evidence points to dark matter?
→ Galactic rotation curves, galaxy cluster dynamics, collisions.

✅ Why is it called dark matter?
→ It doesn’t emit or absorb light.

✅ How much of the universe is dark matter?
→ ~30%.

✅ What are its properties?
→ Non-luminous, interacts via gravity, unknown particle nature.

✅ Have we detected dark matter particles?
→ No, only indirect evidence.

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