How The Life Begin

The history of Earth concerns the development of  planet   Earth  from its formation to the present day.Nearly all branches of  natural science  have contributed to understanding of the main events of Earth's past, characterized by constant  geological change and biological  evolution . The geological time scale (GTS), as defined by international convention,depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history. (In the graphic:  Ga  means "billion years ago";  Ma , "million years ago".) Earth formed around 4.54 billion years ago, approximately one-third the  age of the universe , by  accretion  from the  solar nebula . Volcanic  outgassing probably created the primordial  atmosphere  and then the ocean, but the early atmosphere contained almost no  oxygen . Much of the Earth was molten bec...

History of the center of the Universe Figure of the heavenly bodies — An illustration of the Ptolemaic geocentric system by Portuguese cosmographer and cartographer  Bartolomeu Velho , 1568 (Bibliothèque Nationale, Paris), depicting Earth as the centre of the Universe. The center of the Universe is a concept that lacks a coherent definition in modern  astronomy ; according to standard  cosmological  theories on the  shape of the universe , it has no center. Historically, the center of the Universe had been believed to be a number of locations. Many mythological cosmologies included an  axis mundi , the central axis of a flat Earth that connects the Earth, heavens, and other realms together. In the 4th century BCE Greece, the  geocentric model  was developed based on astronomical observation, proposing that the center of the Universe lies at the center of a spherical, stationary Earth, around which the sun, moon, planets, a...

Loop quantum gravity Loop quantum gravity ( LQG ) is a theory of  quantum gravity , merging  quantum mechanics  and  general relativity , making it a possible candidate for a  theory of everything . Its goal is to unify gravity in a common theoretical framework with the other three  fundamental forces  of nature, beginning with relativity and adding quantum features. It competes with  string theory that begins with  quantum field theory and adds gravity. From the point of view of  Einstein 's theory, all attempts to treat gravity as another quantum force equal in importance to electromagnetism and the nuclear forces have failed. According to Einstein, gravity is not a force – it is a property of  spacetime itself . Loop quantum gravity is an attempt to develop a quantum theory of gravity based directly on Einstein's geometric formulation. To do this, in LQG theory space and time are  quantized , analogously to the w...

N ext point will be quantum loop gravity

This subfield originated in 1999 by  Martin Bojowald , and further developed in particular by  Abhay Ashtekar  and  Jerzy Lewandowski , as well as  Tomasz Pawłowski  and  Parampreet Singh , et al. In late 2012 LQC represents a very active field in  physics , with about three hundred papers on the subject published in the literature. There has also recently been work by  Carlo Rovelli , et al. on relating LQC to the  spinfoam -based  spinfoam cosmology . However, the results obtained in LQC are subject to the usual restriction that a truncated classical theory, then quantized, might not display the true behaviour of the full theory due to artificial suppression of degrees of freedom that might have large quantum fluctuations in the full theory. It has been argued that singularity avoidance in LQC are by mechanisms only available in these restrictive models and that singularity avoidance in the full theory can still be obtained ...

Loop  quantum cosmology  (LQC) is a  finite ,  symmetry -reduced model of  loop quantum gravity  ( LQG ) that predicts a "quantum bridge" between contracting and expanding  cosmological  branches. The distinguishing feature of LQC is the prominent role played by the  quantum geometry  effects of loop quantum gravity (LQG). In particular,  quantum geometry  creates a brand new repulsive force which is totally negligible at low space-time curvature but rises very rapidly in the  Planck regime , overwhelming the classical gravitational attraction and thereby resolving  singularities of general relativity . Once singularities are resolved, the conceptual paradigm of  cosmology changes and one has to revisit many of the standard issues—e.g., the " horizon problem "—from a new perspective. Since LQG is based on a specific quantum theory of  Riemannian geometry , geometric observables display a f...

De Sitter space Ekpyrotic universe  − a string-theory-related model depicting a  five-dimensional ,  membrane -shaped universe; an alternative to the  Hot Big Bang Model , whereby the universe is described to have originated when two membranes collided at the fifth dimension Extra dimensions in string theory  for 6 or 7 extra space-like dimensions all with a compact topology History of the center of the Universe Holographic principle List of cosmology paradoxes Theorema Egregium  − The "remarkable theorem" discovered by  Gauss , which showed there is an intrinsic notion of curvature for surfaces. This is used by  Riemann  to generalize the (intrinsic) notion of curvature to higher-dimensional spaces Three-torus model of the universe Zero-energy universe  – hypothesis that the total amount of energy in the universe is exactly zero

Milne model ("spherical" expanding) Main article:  Milne model If one applies  Minkowski space -based  special relativity  to expansion of the universe, without resorting to the concept of a  curved spacetime , then one obtains the Milne model. Any spatial section of the universe of a constant age (the  proper time  elapsed from the Big Bang) will have a negative curvature; this is merely a  pseudo-Euclidean  geometric fact analogous to one that  concentric  spheres in the flat  Euclidean space  are nevertheless curved. Spatial geometry of this model is an unbounded  hyperbolic space . The entire universe is contained within a  light cone , namely the future cone of the Big Bang. For any given moment t> 0 of  coordinate time (assuming the Big Bang has t = 0), the entire universe is bounded by a  sphere  of radius exactly  c  t. The apparent paradox of an inf...

When cosmologists speak of the universe as being "open" or "closed", they most commonly are referring to whether the curvature is negative or positive. These meanings of open and closed are different from the mathematical meaning of open and closed used for sets in topological spaces and for the mathematical meaning of open and closed manifolds, which gives rise to ambiguity and confusion. In mathematics, there are definitions for a  closed manifold  (i.e., compact without boundary) and  open manifold  (i.e., one that is not compact and without boundary). A "closed universe" is necessarily a closed manifold. An "open universe" can be either a closed or open manifold. For example, in the  Friedmann–Lemaître–Robertson–Walker  (FLRW) model the universe is considered to be without boundaries, in which case "compact universe" could describe a universe that is a closed manifold.

Universe with negative curvature A hyperbolic universe, one of a negative spatial curvature, is described by  hyperbolic geometry , and can be thought of locally as a three-dimensional analog of an infinitely extended saddle shape. There are a great variety of  hyperbolic 3-manifolds , and their classification is not completely understood. Those of finite volume can be understood via the  Mostow rigidity theorem . For hyperbolic local geometry, many of the possible three-dimensional spaces are informally called "horn topologies", so called because of the shape of the  pseudosphere , a canonical model of hyperbolic geometry. An example is the  Picard horn , a negatively curved space, colloquially described as "funnel-shaped".

Universe with positive curvature Universe in an expanding sphere. The galaxies farthest away are moving fastest and hence experience length contraction and so become smaller to an  observer in the centre . A positively curved universe is described by  elliptic geometry , and can be thought of as a three-dimensional  hypersphere , or some other  spherical 3-manifold (such as the  Poincaré dodecahedral space ), all of which are quotients of the 3-sphere. Poincaré dodecahedral space , a positively curved space, colloquially described as "soccerball-shaped", as it is the quotient of the 3-sphere by the  binary icosahedral group , which is very close to  icosahedral symmetry , the symmetry of a soccer ball. This was proposed by  Jean-Pierre Luminet  and colleagues in 2003 and an optimal orientation on the sky for the model was estimated in 2008.

In a universe with zero curvature, the local geometry is  flat . The most obvious global structure is that of  Euclidean space , which is infinite in extent. Flat universes that are finite in extent include the  torus  and  Klein bottle . Moreover, in three dimensions, there are 10 finite closed flat 3-manifolds, of which 6 are orientable and 4 are non-orientable. These are the  Bieberbach manifolds . The most familiar is the aforementioned  3-torus universe . In the absence of dark energy, a flat universe expands forever but at a continually decelerating rate, with expansion asymptotically approaching zero. With dark energy, the expansion rate of the universe initially slows down, due to the effect of gravity, but eventually increases. The  ultimate fate of the universe  is the same as that of an open universe. A flat universe can have  zero total energy .

The curvature of the universe places constraints on the topology. If the spatial geometry is  spherical , i.e., possess positive curvature, the topology is compact. For a flat (zero curvature) or a hyperbolic (negative curvature) spatial geometry, the topology can be either compact or infinite. Many textbooks erroneously state that a flat universe implies an infinite universe; however, the correct statement is that a flat universe that is also  simply connected  implies an infinite universe. For example, Euclidean space is flat, simply connected, and infinite, but the  torus  is flat, multiply connected, finite, and compact. In general,  local to global theorems  in  Riemannian geometry  relate the local geometry to the global geometry. If the local geometry has constant curvature, the global geometry is very constrained, as described in  Thurston geometries . The latest research shows that even the most powerful future exper...

Assuming a finite universe, the universe can either have an edge or no edge. Many finite mathematical spaces, e.g., a  disc , have an edge or boundary. Spaces that have an edge are difficult to treat, both conceptually and mathematically. Namely, it is very difficult to state what would happen at the edge of such a universe. For this reason, spaces that have an edge are typically excluded from consideration. However, there exist many finite spaces, such as the  3-sphere  and  3-torus , which have no edges. Mathematically, these spaces are referred to as being  compact without boundary. The term compact basically means that it is finite in extent ("bounded") and  complete . The term "without boundary" means that the space has no edges. Moreover, so that calculus can be applied, the universe is typically assumed to be a  differentiable manifold . A mathematical object that possesses all these properties, compact without boundary and differentiable, is t...

One of the presently unanswered questions about the universe is whether it is infinite or finite in extent. For intuition, it can be understood that a finite universe has a finite volume that, for example, could be in theory filled up with a finite amount of material, while an infinite universe is unbounded and no numerical volume could possibly fill it. Mathematically, the question of whether the universe is infinite or finite is referred to as  boundedness . An infinite universe (unbounded metric space) means that there are points arbitrarily far apart: for any distance d, there are points that are of a distance at least d apart. A finite universe is a bounded metric space, where there is some distance d such that all points are within distance d of each other. The smallest such d is called the diameter of the universe, in which case the universe has a well-defined "volume" or "scale."

Global structure covers the  geometry and the  topology  of the whole universe—both the observable universe and beyond. While the local geometry does not determine the global geometry completely, it does limit the possibilities, particularly a geometry of a constant curvature. The universe is often taken to be a  geodesic manifold , free of  topological defects ; relaxing either of these complicates the analysis considerably. A global geometry is a local geometry plus a topology. It follows that a topology alone does not give a global geometry: for instance, Euclidean 3-space and  hyperbolic 3-space  have the same topology but different global geometries. As stated in the introduction, investigations within the study of the global structure of the universe include: Whether the universe is  infinite  or finite in extentWhether the geometry of the global universe is flat, positively curved, or negatively curvedWhether the topology is...

These and other astronomical measurements constrain the spatial curvature to be very close to zero, although they do not constrain its sign. This means that although the local geometries of spacetime are generated by the theory of relativity based on  spacetime intervals , we can approximate 3-space by the familiar  Euclidean geometry . The  Friedmann–Lemaître–Robertson–Walker (FLRW) model  using  Friedmann equations  is commonly used to model the universe. The FLRW model provides a curvature of the universe based on the mathematics of  fluid dynamics , that is, modeling the matter within the universe as a perfect fluid. Although stars and structures of mass can be introduced into an "almost FLRW" model, a strictly FLRW model is used to approximate the local geometry of the observable universe. Another way of saying this is that if all forms of  dark energy  are ignored, then the curvature of the universe can...

General relativity  explains that mass and energy bend the curvature of spacetime and is used to determine what curvature the universe has by using a value called the  density parameter , represented with Omega (Ω). The density parameter is the average density of the universe divided by the critical energy density, that is, the mass energy needed for a universe to be flat. Put another way, If Ω = 1, the universe is flatIf Ω > 1, there is positive curvatureif Ω < 1 there is negative curvature One can experimentally calculate this Ωto determine the curvature two ways. One is to count up all the mass-energy in the universe and take its average density then divide that average by the critical energy density. Data from  Wilkinson Microwave Anisotropy Probe  (WMAP) as well as the  Planck spacecraft  give values for the three constituents of all the mass-energy in the universe – normal mass ( baryonic matter  and  dark ma...

The  curvature  is a quantity describing how the geometry of a space differs locally from the one of the  flat space . The curvature of any locally  isotropic space  (and hence of a locally isotropic universe) falls into one of the three following cases: Zero curvature (flat); a drawn triangle's angles add up to 180° and the  Pythagorean theorem  holds; such 3-dimensional space is locally modeled by  Euclidean space  E 3 .Positive curvature; a drawn triangle's angles add up to more than 180°; such 3-dimensional space is locally modeled by a region of a  3-sphere  S 3 .Negative curvature; a drawn triangle's angles add up to less than 180°; such 3-dimensional space is locally modeled by a region of a  hyperbolic space  H 3 . Curved geometries are in the domain of  Non-Euclidean geometry . An example of a positively curved space would be the surface of a sphere such as the Earth. A triangle drawn from th...

As stated in the introduction, there are two aspects to consider: its local geometry, which predominantly concerns the curvature of the universe, particularly the  observable universe , andits  global geometry, which concerns the topology of the universe as a whole. The observable universe can be thought of as a sphere that extends outwards from any observation point for 46.5 billion light years, going farther back in time and more  redshifted  the more distant away one looks. Ideally, one can continue to look back all the way to the  Big Bang ; in practice, however, the farthest away one can look using light and other  electromagnetic radiation  is the  cosmic microwave background (CMB), as anything past that was opaque. Experimental investigations show that the observable universe is very close to  isotropic  and  homogeneous . If the observable universe encompasses the entire universe, we may be able to determin...

The shape of the universe is the  local and  global geometry  of the  universe . The local features of the geometry of the universe are primarily described by its  curvature , whereas the  topology  of the universe describes general global properties of its shape as of a continuous object. The shape of the universe is related to  general relativity , which describes how  spacetime  is curved and bent by mass and energy. Cosmologists distinguish between the  observable universe  and the global universe. The observable universe consists of the part of the universe that can, in principle, be observed by light reaching Earth within the age of the universe. It encompasses a region of space that  currently  forms a ball centered at Earth of estimated radius 46 billion light-years (4.4×10 26  m). This does not mean the universe is 46 billion years old; in fact, the universe  is believed to be 1...

Is presence in Goldilocks belt enough for having life on a planet? No, besides distance from the sun, if the atmospheric condition of the planet is accurate to form and sustain water to its surface, can only have the possibility of life. For instance, like Earth and Mars, Venus too considered in the habitable zone of the sun, but life chosen the earth only. Why? NASA's Mars rover mission evidences the ancient bacterial life on mars . Later, due to the thin atmospheric layer it was not able to sustain water to its surface. On the other hand, Venus is too hot to origin the life. Its atmosphere consist a very thick layer of carbon dioxide. It absorbs sun energy and restricts revert it back, thus create a non habitable furnace.   Bottlenecks for origin of life in the Goldilocks zoned planets: Billions planets in such zones in the universe orbit around different stars. For instance, NASA claims its recently discovered  TRAPPIST-1 planetary system have ...

What is Goldilocks zone? The origin of life requires a planet locate at a distance from its star having neither too cold nor too hot atmospheric conditions. Such moderate zones with life possibility exist around the certain stars, and the astronomers define this term asGoldilocks zone. Why it is so important to us? Today, it is very important for the astro biologists to search the extraterrestrial life locations in the universe. In future, the decreasing natural resources on earth and the extraterrestrial threats may compel human species to migrate for the new rendezvous. Thus the astronomers continuously peeping into the deep universe to spot such meaningful locations for the future invasions. What is a habitable zone around a star? Different stars depending on their brightness levels and burning tendency of its inside nuclear plants can have varying distances to the Goldilocks area. Water - the key ingredient for life can be formed only on a planet existing in such...

Goldilocks conditions The  Earth  is ideally located in a  Goldilocks condition —being neither too close nor too distant from the Sun. A theme in Big History is what has been termed Goldilocks conditions or the  Goldilocks principle , which describes how "circumstances must be right for any type of complexity to form or continue to exist," as emphasized by Spier in his recent book.For humans, bodily temperatures can neither be too hot nor too cold; for life to form on a planet, it can neither have too much nor too little energy from sunlight. Stars require sufficient quantities of  hydrogen , sufficiently packed together under tremendous gravity, to cause  nuclear fusion . Christian suggests that the universe creates complexity when these Goldilocks conditions are met, that is, when things are not too hot or cold, not too fast or slow. For example, life began not in solids (molecules are stuck together, preventing the right kinds of associations) ...

1. T he universe appears, incredibly hot, busting, expanding, within a second. 2.Stars are born. 3.Stars die, creating temperatures hot enough to make complex chemicals, as well as rocks, asteroids, planets, moons, and our solar system. 4.Earth is created. 5.Life appears on Earth, with molecules growing from the  Goldilocks conditions , with neither too much nor too little energy. 6.Humans appear, language, collective learning. 7.Christian elaborated that more complex systems are more fragile, and that while collective learning is a powerful force to advance humanity in general, it is not clear that humans are in charge of it, and it is possible in his view for humans to destroy the  biosphere  with the powerful weapons that have been invented. In the 2008 lecture series through  The Teaching Company's Great Courses entitled Big History: The Big Bang, Life on Earth, and the Rise of Humanity, Christian explains Big History in terms of eight thresholds of i...

Cosmic evolution is more than a subjective, qualitative assertion of "one damn thing after another". This inclusive scientific worldview constitutes an objective, quantitative approach toward deciphering much of what comprises organized, material Nature. Its uniform, consistent philosophy of approach toward all complex systems demonstrates that the basic differences, both within and among many varied systems, are of degree, not of kind. And, in particular, it suggests that optimal ranges of energy rate density grant opportunities for the evolution of complexity; those systems able to adjust, adapt, or otherwise take advantage of such energy flows survive and prosper, while other systems adversely affected by too much or too little energy are non-randomly eliminated. Fred Spier is foremost among those big historians who have found the concept of energy flows useful, suggesting that Big History is the rise and demise of complexity on all scales, from sub-microscopic particles ...

Notable among quantitative efforts to describe cosmic evolution are  Eric Chaisson 's research efforts to describe the concept of energy flow through open,  thermodynamic  systems, including galaxies, stars, planets, life, and society. The observed increase of  energy rate density (energy/time/mass) among a whole host of complex systems is one useful way to explain the rise of complexity in an  expanding universe  that still obeys the cherished  second law of thermodynamics  and thus continues to accumulate net  entropy . As such, ordered material systems—from buzzing bees and redwood trees to shining stars and thinking beings—are viewed as temporary, local islands of order in a vast, global sea of disorder. A recent review article, which is especially directed toward big historians, summarizes much of this empirical effort over the past decade. One striking finding of such complexity studies is the apparently ranked order a...

Cosmic evolution is a quantitative subject, whereas big history typically is not; this is because cosmic evolution is practiced mostly by natural scientists, while big history by social scholars. These two subjects, closely allied and overlapping, benefit from each other; cosmic evolutionists tend to treat universal history linearly, thus humankind enters their story only at the most very recent times, whereas big historians tend to stress humanity and its many cultural achievements, granting human beings a larger part of their story. One can compare and contrast these different emphases by watching two short movies portraying the Big-Bang-to -humankind narrative, one animating time linearly, and the other capturing time (actually look-back time) logarithmically; in the former, humans enter this 14-minute movie in the last second, while in the latter we appear much earlier—yet both are correct. These different treatments of time over ~14 billion years, each with different emphases ...