"dark energy is an unknown form of energy that affects the universe on the largest scales."
This is a subfield that studies the role of dark energy in the expansion and acceleration of the universe.
Introduction to Cosmology: This topic covers the basics of the study of the structure, origin, and evolution of the universe.
General Relativity: This topic discusses Einstein's theory of general relativity, which describes the curvature of spacetime and the nature of gravity.
Friedmann Equation: This topic discusses the equation that describes the expansion of the universe and how it changes with time.
Cosmic Microwave Background Radiation (CMB): This topic covers the leftover radiation from the Big Bang and how it can be used to study the early universe.
Large Scale Structure of the Universe: This topic covers the distribution of matter in the universe and how it is related to the expansion of the universe.
Dark Matter: This topic deals with the unseen matter in the universe that interacts with gravity but not with light.
Observational Cosmology: This topic covers the technologies used to observe the universe, including telescopes, satellites, and other equipment.
Supernovae: This topic deals with the study of supernovae explosions and how they can be used to measure the expansion of the universe.
Dark Energy: This topic covers the mysterious force that is causing the universe to accelerate in its expansion, and how it is related to the geometry of the universe.
Luminosity Distance: This topic deals with how the distance between objects in the universe can be calculated using their observed brightness.
Hubble’s Law: This topic covers the relationship between the distance of objects from us and their recession velocity, as discovered by Edwin Hubble.
Baryon Acoustic Oscillations (BAOs): This topic discusses the distribution of matter in the universe on large scales, and how it can be used to study dark energy.
Gravitational Lensing: This topic covers the bending of light by gravity, and how it can be used to study the distribution of matter in the universe.
Inflation: This topic discusses the theory of cosmic inflation, which proposes that the universe underwent a period of exponential expansion in the first moments after the Big Bang.
Multiverse: This topic deals with the possibility of there being multiple universes, and how such a concept may arise from dark energy cosmology.
Quantum Physics: This topic covers the study of the fundamental particles and forces that make up the universe and how they interact.
Black Holes: This topic covers the phenomenon of black holes, which are regions of spacetime where gravity is so strong that nothing can escape.
Neutrinos: This topic covers the elusive particles that are very difficult to detect and can provide insight into the early universe.
Cosmic Infrared Background: This topic covers the study of the infrared radiation emitted by the universe and how it can be used to learn about its history.
Dark Energy Survey: This topic covers the ongoing large-scale survey of the universe designed to study dark energy and other phenomena.
Lambda-CDM model: This is the most widely accepted and commonly used model for Dark Energy Cosmology. It postulates that Dark Energy is a cosmological constant (represented by the Greek letter lambda) that causes the universe to expand at an accelerated rate. The model also includes Cold Dark Matter (CDM), which is an invisible form of matter that helps explain the formation of large-scale structures in the universe.
Modified Gravity: Some scientists propose that Dark Energy is not an actual force, but rather a manifestation of a modification to Einstein's theory of General Relativity that governs the behavior of gravity at large scales. These modifications would cause the expansion of the universe to accelerate without the need for Dark Energy.
Quintessence: This theory proposes that Dark Energy is a new, scalar field that behaves like a fluid and causes gravitational repulsion. The field could be either constant, or it could evolve over time, leading to different rates of cosmic expansion.
Phantom Energy: This model proposes that Dark Energy follows an equation of state that is less than -1, which means that it has a negative energy density and negative pressure. This negative pressure would amplify over time, leading to the eventual "Big Rip" of the universe.
Chameleon Field: This theory postulates that Dark Energy is a scalar field that behaves differently in different environments. In regions of high energy density, it would behave like normal Dark Energy and cause the universe to accelerate; in low-energy regions, it would behave like ordinary matter and interact with gravity.
Gravitational Waves: This theory posits that Dark Energy is a form of gravitational waves, which would fill the universe and cause it to expand at an accelerated rate.
"Its primary effect is to drive the accelerating expansion of the universe."
"...dark energy is the dominant component of the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary matter contribute 26% and 5%, respectively."
"Dark energy's density is very low: 6×10−10 J/m3 (≈7×10−30 g/cm3), much less than the density of ordinary matter or dark matter within galaxies."
"...it dominates the universe's mass–energy content because it is uniform across space."
"The first observational evidence for dark energy's existence came from measurements of supernovae."
"Scientists thought that the gravitational attraction of matter and energy in the universe would cause the universe's expansion to slow down over time."
"Comparing this distance to the redshift (which measures the speed at which the supernova is receding) shows that the universe's expansion is accelerating."
"Since the discovery of accelerating expansion, several independent lines of evidence have been discovered that support the existence of dark energy."
"The main candidates are a cosmological constant (representing a constant energy density filling space homogeneously) and scalar fields (dynamic quantities having energy densities that vary in time and space) such as quintessence or moduli."
"A cosmological constant would remain constant across time and space, while scalar fields can vary."
"Yet other possibilities are interacting dark energy, an observational effect, and cosmological coupling."
"Dark energy's density is very low: 6×10−10 J/m3 (≈7×10−30 g/cm3)."
"dark matter...contribute[s] 26% of the total energy in the present-day observable universe."
"dark energy...affects the universe on the largest scales."
"Dark energy's density is...much less than the density of ordinary matter or dark matter within galaxies."
"Its primary effect is to drive the accelerating expansion of the universe."
"...dark energy is the dominant component of the universe."
"The first observational evidence for dark energy's existence came from measurements of supernovae."
"...the universe's expansion is accelerating... scientists thought that the gravitational attraction of matter and energy in the universe would cause the universe's expansion to slow down over time."