Cosmology Cheatsheet
Basic Concepts
- Cosmology: The study of the universe on its largest scales.
- Universe: Everything that exists, including all matter and energy.
- Big Bang Theory: The prevailing theory of the origin and evolution of the universe.
- Dark Matter: Matter that does not interact with light and cannot be detected directly, but can be inferred from its gravitational effects on visible matter.
- Dark Energy: A hypothetical form of energy that is thought to permeate all of space and accelerate the expansion of the universe.
History of the Universe
- Planck Epoch: The earliest known period of the universe, which lasted from the beginning of time to 10^-43 seconds.
- Grand Unification Epoch: A period of the universe’s history, from 10^-43 seconds to 10^-36 seconds, when the strong, weak, and electromagnetic forces were unified.
- Inflationary Epoch: A brief period of exponential expansion of the universe, occurring at around 10^-36 seconds after the Big Bang.
- Electroweak Epoch: A period from 10^-36 seconds to 10^-12 seconds after the Big Bang, when the strong and electroweak forces separated.
- Particle Era: The period from 10^-12 seconds to 380,000 years after the Big Bang, when particles combined to form atoms.
- Era of Nucleosynthesis: The time period from 3 to 20 minutes after the Big Bang, when light elements were formed.
- Era of Recombination: The period about 380,000 years after the Big Bang, when atoms formed and the universe became transparent to radiation.
- Cosmic Microwave Background: Radiation left over from the Big Bang, which fills the entire universe and is observed as a faint glow in the microwave region of the electromagnetic spectrum.
- Era of Galaxies: The period from about 400 million years after the Big Bang to the present, during which galaxies formed and evolved.
Theories and Models
- Lambda-CDM Model: The most widely accepted model of the universe, which includes dark matter and dark energy.
- Inflationary Cosmology: A theory that proposes the universe underwent a brief period of exponential expansion at the beginning of time.
- Multiverse Theory: The idea that there may be multiple universes, each with different physical laws and constants.
- String Theory: A theoretical framework that attempts to unify all the forces of nature and explain the fundamental nature of matter and energy.
Observations and Measurements
- Redshift: The phenomenon in which light from distant objects is shifted towards longer wavelengths, indicating that the object is moving away from us.
- Cosmic Distance Ladder: A series of methods used to measure distances to celestial objects, including parallax, standard candles, and redshift.
- Hubble’s Law: The observation that the farther away a galaxy is, the faster it appears to be moving away from us.
- Cosmic Microwave Background Radiation: Radiation left over from the Big Bang, which provides a snapshot of the universe about 380,000 years after the Big Bang.
- Edwin Hubble: American astronomer who first observed and described the expansion of the universe.
- Georges Lemaître: Belgian physicist and astronomer who proposed the Big Bang Theory.
- Stephen Hawking: British physicist who made significant contributions to our understanding of black holes, the Big Bang, and the origin of the universe.
Resources for Cosmology
Websites
Journals
Books
- Cosmology by Steven Weinberg
- The Early Universe by Edward Kolb and Michael Turner
- Cosmology for the Curious by Delia Perlov and Alex Vilenkin
- An Introduction to Modern Cosmology by Andrew Liddle
- The Large Scale Structure of Space-Time by Stephen Hawking and George Ellis