#cosmology_140 1) Cosmology studies the properties of the universe. This discipline was born in the 1920s thanks to Edwin Hubble. 2) Cosmology focuses on the history of the Universe and tells us clearly that our galaxy is one of a huge number.

#cosmology_140 The cosmic microwave background (CMB) is practically isotropic, the same in all spatial directions. That means the almost homogeneity of the space at the moment of being generated.

#cosmology_140 The distance between the Earth and the Moon (1.3 light-second) allows all the planets to fit into a radius. See this pretty image

#cosmology_140 Theory of special relativity ignores gravity and uses a 4-dimensional space with the Minkoswky metric and Lorentz transformations

#cosmology_140 Gravity warps space-time, making it curved.

#cosmology_140 The GRT tells us that gravity is caused by the energy-moment tensor that is related to the curvature tensor by this equation:

#cosmology_140 The Einstein field equation is as fundamental as Maxwell's equations for Electromagnetism.

#cosmology_140 A black hole, rotating or not, is an object from which light cannot escape. Even photons are trapped.

#cosmology_140 Newton's Physics assumes the existence of universal time along with a cartesian coordinate system.

#cosmology_140 We are an insignificant planet in a very remote galaxy, inhabited by an underdeveloped civilization. We are a single point.

#cosmology_140 The time measured by observers traveling at relativistic speed passes more slowly than for those at non-relativistic speed.

#cosmology_140 Newton´s theory of gravitation (so successful) is an approximation to General Relativity Theory.

#cosmology_140 Gravitational waves are oscillating solutions, traveling through space-time, of the Einstein field equation of GRT

#cosmology_140 Gravity causes space-time to be curved.

#cosmology_140 A gravitational wave is a beam of gravitons, hypothetical elementary particles in QFT.

#cosmology_140 Graviton mediates the force of gravitation, it is massless and a spin-2 boson, a tensor boson.

#cosmology_140 Gravitational waves are generated by any object accelerating, and electromagnetic waves are generated by charged object accelerating

#cosmology_140 Individual gravitons are created from vacuum fluctuations, like photons.

#cosmology_140 We don´t know about the whole Universe, we only know about the part of the Universe that we can see.

#cosmology_140 The observable Universe is a sphere of radius 14 Gpc= 46 GL-y= 46000 ML-y.

#cosmology_140 We are on the Edge of a large galaxy, Milky Way. Galileo in 1610 saw the stars of Milky Way.

#cosmology_140 Only 4 galaxies are visible to the naked eye: Milky Way, Andromeda Nebula (northern), Small and Large Magallanes clouds (southern).

#cosmology_140 Larger galaxies have a Black Hole (BH) at their center. The mass of this BH is about 1 million times the solar mass.

#cosmology_140 A large amount of matter is falling into black holes, generating intense electromagnetic and gravitational waves.

#cosmology_140 Most galaxies are grouped in galaxy clusters.

If you like cosmology (time travel) you are invited to consult the thread #cosmology_140 by Prof. Enrique Arribas @55enrique.

#cosmology_140 A scientific study estimates that there are 100 million black holes in the Milky Way galaxy with masses tens of times that of the Sun.

#cosmology_140 About 90 M of these Black Holes are less than 30 times the mass of the Sun. About 10 M are larger, with >30 times its mass.

#cosmology_140 Gravitational Waves are produced by close binaries, pair of very nearby objects that are rotating around each other.

#cosmology_140 If a Gravitational Wave is emitted, the distance between the pair decreases so that their orbit spiral inwards.

#cosmology_140 In 2016 a burst of Gravitational Waves was observed due to spiraling orbit and final collision.

#cosmology_140 The observation of Gravitational Waves was performed with a laser interferometer: LIGO

#cosmology_140 In 2016 GWs were detected with an amplitude of 1E-32 m, which came from the collision of two BH at 1E9 y-l from us.

At the beginnig: cosmic inflation

Cosmology of Incas

Maya Cosmology

Tenochtitlán

Lower world (inframundo)

Tree of life Mayan universe

Parallel Universes: multiverses https://www.cronica.com.mx/notas-los_universos_paralelos_un_concepto_que_genera_debate_en_ciencia_y_cultura-1158549-2020

#cosmology_140 In addition to the baryons, the Universe contains Cold Dark Matter (CDM).

#cosmology_140 Cold Dark Matter doesn´t emit any type of radiation.

#cosmology_140 The particles of Cold Dark Matter have barely any random motion.

#cosmology_140 The most well-known equation in Physics, and at the same time one of the worst understood, is energy equal to mass times the speed of light squared.

#cosmology_140 The Higgs field interacts through its famous boson with almost all particles. From this interaction arises the mass of each particle.

#cosmology_140 The Higgs field is transparent to photons. They do not interact with this field. Therefore, photons have no rest mass.

#cosmology_140 In General Relativity vector fields interact with spacetime in four dimensions. Space-time is no longer an immutable container, now it participates in the interaction.

#cosmology_140 The geometry of spacetime is variable and distorted (and is distorted) by vector fields.

#cosmology_140 Photons deviate from their rectilinear path as they pass near massive objects, which behave like gravitational lenses, producing refraction.

#cosmology_140 Quantum gravity should be the key to understanding highly energetic configurations, such as the origin of the universe or black holes.

#cosmology_140 The main tool of cosmology is the Theory of General Relativity.

#cosmology_140 The universe is isotropic (it is the same in all directions) and homogeneous (it has the same properties at all points).

#cosmology_140 The properties of the cosmic background radiation confirm the isotropy and homogeneity of the universe.

#cosmology_140 Isotropy and homogeneity lead us to think that the universe has no center. It is not an expanding sphere.

#cosmology_140 An effort must be made to understand this statement: the universe does not have a special point that we can call the center.

#cosmology_140 It can be said in another equivalent way: All points in the universe are the center of the universe.

#cosmology_140 There are two types of matter: the usual and the dark.

#cosmology_140 We know that the universe is in accelerating expansion.

#cosmology_140 If Cold Dark Matter (CDM) doesn´t absorb any either is called Cold Transparent Matter.

#cosmology_140 We only know the physical properties of Cold and Dark Matter through its gravitational effect.

#cosmology_140 Most of the Cold Dark Matter is distributed throughout the Universe

#cosmology_140 The Universe contains electromagnetic radiation: photons

#cosmology_140 Photons were emitted before there were any stars.

#cosmology_140 At the beginning of the Universe there was a soup of photons and electrons, together with other particles.

#cosmology_140 After atoms were generated the photons were allowed to move freely

#cosmology_140 Those primitive photons traveling with v=c are called Cosmic Microwave Background (CMB).

#cosmology_140 The Cosmic Microwave Background is almost isotropic because the early Universe was almost homogenized.

#cosmology_140 The slight anisotropy of the universe is crucial for cosmology.

#cosmology_140 The universe also contains neutrinos which constitute the Cosmic Microwave Background (CMB), not yet directly detected.

#cosmology_140 Some objects in the universe emit particles and nuclei that reach Earth: these are the so-called primary cosmic rays

#cosmology_140 The cosmic rays (very high energy gamma rays) reach us from all directions.

#cosmology_140 Primary cosmic rays are electrons and nuclei (H, He) with a tiny fraction of positrons and antiprotons.

#cosmology_140 When primary cosmic rays penetrate the atmosphere, they produce secondary cosmic rays.

#cosmology_140 It is known the history of the universe in its second stage, up to the present when it is 1.38E10 years old.

#cosmology_140 The Big Bang was probably preceded by a period called inflation.

#cosmology_2020 While inflation lasted, the Universe was expanding at an ever faster rate because it contained fields instead of particles.

#cosmology_2020 The expansion of the Universe is homogeneous (it is the same everywhere) and isotropic (it is the same in all directions).

#cosmology_2020 Very few minutes after the Big Bang, neutrons combine with protons to form nuclei. This phenomenon is called Big Bang Nucleosynthesis (BBN). BBN begins with the formation of deuterium nuclei.

#cosmology_2020 After the formation of the light nuclei, nothing seems to happen for about half a million years. Follow the expansion in a very relaxed and predictable way.

#cosmology_2020 Suddenly, almost all the electrons in the Universe were attracted to the protons, forming helium and hydrogen atoms.

#cosmology_2020 70% of today's energy density comes from a vacuum. That vacuum energy density is called the cosmological constant because it does not change with time.

#cosmology_2020 We know that the cosmological constant exists because we can measure its gravitational effect.