Exam 3 Stars and Galaxies

Age of the Universe

approximately 13.8 billion years, is determined using Hubble's Law and measurements of the Cosmic Microwave Background Radiation (CMBR).

Alan Guth

a physicist who proposed the theory of cosmic inflation, which explains the rapid expansion of the Universe moments after the Big Bang.

Big Bang Theory

describes the origin of the Universe as an expansion from an extremely hot and dense singularity, supported by evidence like the CMBR and Hubble's Law.

Big Crunch

a theoretical scenario where the Universe's expansion reverses, causing it to collapse into a singularity.

Blazars

a type of active galactic nucleus with a jet pointed directly at Earth, emitting strong electromagnetic radiation across all wavelengths.

Clusters

groups of galaxies bound by gravity

Superclusters

are vast networks of galaxy clusters forming the largest known structures in the Universe.

Cosmic Microwave Background Radiation (CMBR)

the residual thermal radiation from the Big Bang, providing a snapshot of the early Universe's state.

Cosmological Constant

a term in Einstein's field equations of General Relativity, associated with the energy density of empty space (vacuum energy).

Cosmological Redshift

the stretching of light to longer wavelengths due to the Universe's expansion, distinct from Doppler redshift caused by relative motion.

Cosmology

the scientific study of the Universe's origin, evolution, structure, and eventual fate.

Dark Energy

a mysterious force driving the accelerated expansion of the Universe.

Dark Matter

an invisible form of matter inferred from its gravitational effects, essential for explaining galaxy rotation curves.

Doppler Redshift

occurs when an object moves away, causing its emitted light to shift to longer wavelengths.

Edwin Hubble / Hubble's Law

discovered the Universe's expansion through observations of galactic redshifts

Electromagnetic Force

one of the four fundamental forces, responsible for interactions between charged particles.

Electroweak Theory

unifies the electromagnetic and weak forces, proposed by Steven Weinberg and others.

Four Fundamental Forces

gravity, electromagnetic, strong nuclear, and weak nuclear forces, governing interactions in the Universe.

Galactic Collisions

occur when galaxies interact gravitationally, often leading to star formation and structural changes.

Gamma-Ray Bursts

short, intense bursts of gamma radiation from cataclysmic events like supernovae or neutron star mergers

General Relativity (GR)

describes gravity as the warping of spacetime by mass and energy, with its central equation being Einstein's field equation.

Gravity Force

the attractive force between masses, crucial for the formation and evolution of cosmic structures.

High Energy Physics

explores fundamental particles and forces at small length scales and high energy levels.

Hubble Flow

describes the movement of galaxies due to the Universe's expansion.

Hubble's Parameter and Law

quantifies the rate of the Universe's expansion and is a key part of Hubble's Law.

Inflation

rapid exponential expansion of the Universe shortly after the Big Bang, resolving issues like homogeneity.

Lawrence Krauss

a cosmologist known for his work on dark energy and the physics of the early Universe.

Local Group

a cluster of galaxies including the Milky Way, Andromeda, and approximately 54 smaller galaxies.

Matter-Dominated Universe

is one where matter density exceeds radiation, as in the present cosmic era.

Quasars

highly luminous active galactic nuclei powered by supermassive black holes, important for studying early galaxies.

Quintessence

hypothetical form of dark energy with dynamic properties, unlike the cosmological constant.

Recessional Velocity

the speed at which galaxies move away due to the Universe's expansion.

Richard Feynman

a physicist known for quantum electrodynamics and Feynman diagrams, which visualize particle interactions.

Special Relativity

imposes constraints on objects moving close to the speed of light, affecting time and space measurements.

Strong Force

binds quarks together to form protons and neutrons, essential for atomic nuclei.

Superstrings and Brane Theory

propose that fundamental particles are one-dimensional strings, aiming to unify physics.

Tully & Fisher's Relation

links galaxy luminosity and rotation speed, used to measure distances in the Universe.

Vacuum Energy

ffrom particle physics we have a reasonable origin of dark energy which is simply known as

Weak Force

governs radioactive decay and neutrino interactions, playing a role in stellar processes.

heisenberg relation

e * t = h