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Astronomy portal. v. t. e. The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components: a cosmological constant, denoted by lambda (Λ), associated with dark energy. the postulated cold dark matter, denoted by CDM. ordinary matter. It is referred to as the standard model of ...
Miyake event. A Miyake event is an observed sharp enhancement of the production of cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope 14. Cl in ice cores, which are all independently dated. At present, five significant events are known (7176 BCE, 5259 BCE, 660 BCE, 774 CE, 993 CE ...
Cosmological horizon. A cosmological horizon is a measure of the distance from which one could possibly retrieve information. [ 1] This observable constraint is due to various properties of general relativity, the expanding universe, and the physics of Big Bang cosmology. Cosmological horizons set the size and scale of the observable universe.
Using the values known in 2018 and Planck units for Ω Λ = 0.6889 ± 0.0056 and the Hubble constant H 0 = 67.66 ± 0.42 (km/s)/Mpc = (2.192 7664 ± 0.0136) × 10 −18 s −1, Λ has the value of = = = where is the Planck length. A positive vacuum energy density resulting from a cosmological constant implies a negative pressure, and vice versa.
In cosmology, the cosmological constant problem or vacuum catastrophe is the substantial disagreement between the observed values of vacuum energy density (the small value of the cosmological constant) and the much larger theoretical value of zero-point energy suggested by quantum field theory . Depending on the Planck energy cutoff and other ...
The horizon problem (also known as the homogeneity problem) is a cosmological fine-tuning problem within the Big Bang model of the universe. It arises due to the difficulty in explaining the observed homogeneity of causally disconnected regions of space in the absence of a mechanism that sets the same initial conditions everywhere.
NGC 1999. NGC 1999, also known as The Cosmic Keyhole, [1] [2] is a dust-filled bright nebula with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a reflection nebula, and shines from the light of the variable star V380 Orionis. It was previously believed that the black patch was a dense ...