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122-489: Established in 1946 through the philanthropy of Linda (1859–1938) and Herbert F. Hall (1858–1941), of the Hall-Bartlett Grain Co., the library is open to the public, and invites individual researchers, academic institutions, and companies from Kansas City and around the world to use the library's research-level collection. Its mission is to act as "guardian of the collective intellectual heritage with regard to

244-573: A Hubble sphere . Some disputed estimates for the total size of the universe, if finite, reach as high as 10 10 10 122 {\displaystyle 10^{10^{10^{122}}}} megaparsecs, as implied by a suggested resolution of the No-Boundary Proposal . Assuming that the Lambda-CDM model is correct, the measurements of the parameters using a variety of techniques by numerous experiments yield

366-462: A best value of the age of the universe at 13.799 ± 0.021 billion years, as of 2015. Over time, the universe and its contents have evolved. For example, the relative population of quasars and galaxies has changed and the universe has expanded . This expansion is inferred from the observation that the light from distant galaxies has been redshifted , which implies that the galaxies are receding from us. Analyses of Type Ia supernovae indicate that

488-433: A certain place is seen through an aperture as in a pair of bellows. He also postulated regarding the formation of thunder and lightning, maintaining that they are caused by the wind becoming compressed inside a thick cloud and suddenly breaking through, causing the loud sound to be heard as the cloud is bursting. He claimed the fissure then looked like a spark because of the contrast with the dark cloud. Anaximander's model set

610-430: A cosmology. When cosmology is used without a qualifier, it often signifies physical cosmology, unless the context makes clear that a different meaning is intended. Physical cosmology (often simply described as 'cosmology') is the scientific study of the universe, from the beginning of its physical existence. It includes speculative concepts such as a multiverse, when these are being discussed. In physical cosmology ,

732-509: A great number of secondary authors. He lived throughout the fifth and fourth centuries, BCE, and was most likely the first philosopher to try to rationalize the system of the Earth, Sun, and Moon by the use of geometry and mathematics. Anaximander was also said to have created the first map of the world, however, like much of the rest of his works, this has been lost since his time. There is, however, documentation of Anaximander being responsible for

854-655: A heliocentric universe. Commonly regarded as the foundation of modern astronomy, the common universal view of the cosmos shifted as Nicolaus Copernicus positioned the Sun as the center of the Universe. Prior to the Copernican Revolution, the Ptolemaic system, also known as the geocentric model, was widely accepted. This put the Earth at the center of the universe, with the Sun and other planets revolving around

976-446: A precedent for succeeding theories, including Copernicus 's system, with the major change being the shift away from the geocentric model and towards the heliocentric model of the universe. The explained model, although accredited to Anaximander, did necessarily take from ideas originated in foreign cultures, such as the astronomical wheels which are known from Persian cosmology. But even without detailed commentary, these elements of

1098-547: A reasonably good account of various observations about the universe. The initial hot, dense state is called the Planck epoch , a brief period extending from time zero to one Planck time unit of approximately 10 seconds. During the Planck epoch, all types of matter and all types of energy were concentrated into a dense state, and gravity —currently the weakest by far of the four known forces —is believed to have been as strong as

1220-414: A refined substance called " quintessence ". This was understood to be a crystalline, completely transparent substance that held all of the superlunary spheres in perfect order. After their creation by God, these spheres did not change except for their rotation above the Earth. Objects below the lunar sphere were subject to constant combination, separation, and recombination. This was because they consisted of

1342-442: A set of four coordinates: ( x , y , z , t ) . On average, space is observed to be very nearly flat (with a curvature close to zero), meaning that Euclidean geometry is empirically true with high accuracy throughout most of the universe. Spacetime also appears to have a simply connected topology , in analogy with a sphere, at least on the length scale of the observable universe. However, present observations cannot exclude

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1464-485: A vast foam-like structure. Discoveries in the early 20th century have suggested that the universe had a beginning and has been expanding since then. According to the Big Bang theory, the energy and matter initially present have become less dense as the universe expanded. After an initial accelerated expansion called the inflationary epoch at around 10 seconds, and the separation of the four known fundamental forces ,

1586-489: A void of atoms as the fundamental elements of physics, while Stoicism postulated a void allowing for the cosmos to expand and contract in volume through its cycles. The Chinese had multiple theories of the processes and components of the cosmos. The most popular of these beliefs was the Xuan Ye theory, the astronomical view of the cosmos as an infinite space with floating pieces of condensed vapor. The Chinese believed that

1708-445: Is a composite particle made of quarks held together by the strong force . Hadrons are categorized into two families: baryons (such as protons and neutrons ) made of three quarks, and mesons (such as pions ) made of one quark and one antiquark . Of the hadrons, protons are stable, and neutrons bound within atomic nuclei are stable. Other hadrons are unstable under ordinary conditions and are thus insignificant constituents of

1830-483: Is accounted for by visible objects; stars, galaxies, nebulas and interstellar gas. This unseen matter is known as dark matter . In the widely accepted ΛCDM cosmological model, dark matter accounts for about 25.8% ± 1.1% of the mass and energy in the universe while about 69.2% ± 1.2% is dark energy , a mysterious form of energy responsible for the acceleration of the expansion of the universe . Ordinary (' baryonic ') matter therefore composes only 4.84% ± 0.1% of

1952-456: Is an alternative name for the universe or its nature or order. Usage of the word cosmos implies viewing the universe as a complex and orderly system or entity. The cosmos is studied in cosmology  – a broad discipline covering scientific, religious or philosophical aspects of the cosmos and its nature. Religious and philosophical approaches may include the cosmos among spiritual entities or other matters deemed to exist outside

2074-417: Is called the observable universe . The proper distance (measured at a fixed time) between Earth and the edge of the observable universe is 46 billion light-years (14 billion parsecs ), making the diameter of the observable universe about 93 billion light-years (28 billion parsecs). Although the distance traveled by light from the edge of the observable universe is close to the age of the universe times

2196-411: Is composed almost completely of dark energy, dark matter, and ordinary matter . Other contents are electromagnetic radiation (estimated to constitute from 0.005% to close to 0.01% of the total mass–energy of the universe) and antimatter . The proportions of all types of matter and energy have changed over the history of the universe. The total amount of electromagnetic radiation generated within

2318-405: Is composed of two types of elementary particles : quarks and leptons . For example, the proton is formed of two up quarks and one down quark ; the neutron is formed of two down quarks and one up quark; and the electron is a kind of lepton. An atom consists of an atomic nucleus , made up of protons and neutrons (both of which are baryons ), and electrons that orbit the nucleus. Soon after

2440-660: Is equal to, less than, or greater than 1. These are called, respectively, the flat, open and closed universes. Observations, including the Cosmic Background Explorer (COBE), Wilkinson Microwave Anisotropy Probe (WMAP), and Planck maps of the CMB, suggest that the universe is infinite in extent with a finite age, as described by the Friedmann–Lemaître–Robertson–Walker (FLRW) models. These FLRW models thus support inflationary models and

2562-618: Is in the Local Group of galaxies, which in turn is in the Laniakea Supercluster . This supercluster spans over 500 million light-years, while the Local Group spans over 10 million light-years. The universe also has vast regions of relative emptiness; the largest known void measures 1.8 billion ly (550 Mpc) across. The observable universe is isotropic on scales significantly larger than superclusters, meaning that

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2684-421: Is inside and outside. However, finite division of space is where time begins, and the division of time is where all beings were first created. It was believed that there are connections between the physical and the psychological worlds, and an equivalence existed between the outer cosmos and the inner cosmos of the individual. This is expressed in the famous sentence – yat pinḍe tad brahmṇḍe , “as in

2806-786: Is subject to the Pauli exclusion principle ; no two leptons of the same species can be in exactly the same state at the same time. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons), and neutral leptons (better known as neutrinos ). Electrons are stable and the most common charged lepton in the universe, whereas muons and taus are unstable particles that quickly decay after being produced in high energy collisions, such as those involving cosmic rays or carried out in particle accelerators . Charged leptons can combine with other particles to form various composite particles such as atoms and positronium . The electron governs nearly all of chemistry , as it

2928-487: Is the Standard Model , a theory that is concerned with electromagnetic interactions and the weak and strong nuclear interactions. The Standard Model is supported by the experimental confirmation of the existence of particles that compose matter: quarks and leptons , and their corresponding " antimatter " duals, as well as the force particles that mediate interactions : the photon , the W and Z bosons , and

3050-430: Is unknown whether or not they are composed of smaller and even more fundamental particles. In most contemporary models they are thought of as points in space. All elementary particles are currently best explained by quantum mechanics and exhibit wave–particle duality : their behavior has both particle-like and wave -like aspects, with different features dominating under different circumstances. Of central importance

3172-869: Is unknown. Dark matter, a mysterious form of matter that has not yet been identified, accounts for 26.8% of the cosmic contents. Dark energy, which is the energy of empty space and is causing the expansion of the universe to accelerate, accounts for the remaining 68.3% of the contents. Matter, dark matter, and dark energy are distributed homogeneously throughout the universe over length scales longer than 300 million light-years (ly) or so. However, over shorter length-scales, matter tends to clump hierarchically; many atoms are condensed into stars , most stars into galaxies, most galaxies into clusters, superclusters and, finally, large-scale galactic filaments . The observable universe contains as many as an estimated 2 trillion galaxies and, overall, as many as an estimated 10 stars – more stars (and earth-like planets) than all

3294-564: The American Academy of Arts and Sciences . It includes academic journals , academic conference proceedings , reference works , publications by the government , and technical reports , industrial standards , engineering society conference papers , U.S. patents , and monographs . In 1995, the Engineering Societies Library (ESL) was transferred to the library, an acquisition equal in significance to

3416-544: The American Institute of Mining, Metallurgical, and Petroleum Engineers , and the Institute of Electrical and Electronics Engineers . The library's distinguished History of Science Collection contains more than 50,000 volumes, including first editions of many landmarks of science and technology. Some of the oldest books date to the fifteenth century. The oldest book in the collection is a 1472 printing of Pliny

3538-581: The Big Bang , primordial protons and neutrons formed from the quark–gluon plasma of the early universe as it cooled below two trillion degrees. A few minutes later, in a process known as Big Bang nucleosynthesis , nuclei formed from the primordial protons and neutrons. This nucleosynthesis formed lighter elements, those with small atomic numbers up to lithium and beryllium , but the abundance of heavier elements dropped off sharply with increasing atomic number. Some boron may have been formed at this time, but

3660-418: The Big Bang , would have completely annihilated each other and left only photons as a result of their interaction. These laws are Gauss's law and the non-divergence of the stress–energy–momentum pseudotensor . Due to the finite speed of light , there is a limit (known as the particle horizon ) to how far light can travel over the age of the universe . The spatial region from which we can receive light

3782-541: The German words Das All , Weltall , and Natur for universe . The same synonyms are found in English, such as everything (as in the theory of everything ), the cosmos (as in cosmology ), the world (as in the many-worlds interpretation ), and nature (as in natural laws or natural philosophy ). The prevailing model for the evolution of the universe is the Big Bang theory. The Big Bang model states that

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3904-635: The Milky Way is roughly 100,000–180,000 light-years in diameter, and the nearest sister galaxy to the Milky Way, the Andromeda Galaxy , is located roughly 2.5 million light-years away. Because humans cannot observe space beyond the edge of the observable universe, it is unknown whether the size of the universe in its totality is finite or infinite. Estimates suggest that the whole universe, if finite, must be more than 250 times larger than

4026-488: The afterlife or world to come , although "aion/aeon" is also at times used in a more other-worldly sense as the eternal plane of the divine. Universe The universe is all of space and time and their contents. It comprises all of existence , any fundamental interaction , physical process and physical constant , and therefore all forms of matter and energy , and the structures they form, from sub-atomic particles to entire galactic filaments . Since

4148-412: The expansion is accelerating . The more matter there is in the universe, the stronger the mutual gravitational pull of the matter. If the universe were too dense then it would re-collapse into a gravitational singularity . However, if the universe contained too little matter then the self-gravity would be too weak for astronomical structures, like galaxies or planets, to form. Since the Big Bang,

4270-404: The general theory of relativity , explains gravity by recognizing that spacetime is not fixed but instead dynamical. In general relativity, gravitational force is reimagined as curvature of spacetime . A curved path like an orbit is not the result of a force deflecting a body from an ideal straight-line path, but rather the body's attempt to fall freely through a background that is itself curved by

4392-560: The gluon . The Standard Model predicted the existence of the recently discovered Higgs boson , a particle that is a manifestation of a field within the universe that can endow particles with mass. Because of its success in explaining a wide variety of experimental results, the Standard Model is sometimes regarded as a "theory of almost everything". The Standard Model does not, however, accommodate gravity. A true force–particle "theory of everything" has not been attained. A hadron

4514-483: The grains of beach sand on planet Earth ; but less than the total number of atoms estimated in the universe as 10 ; and the estimated total number of stars in an inflationary universe (observed and unobserved), as 10 . Typical galaxies range from dwarfs with as few as ten million (10 ) stars up to giants with one trillion (10 ) stars. Between the larger structures are voids , which are typically 10–150 Mpc (33 million–490 million ly) in diameter. The Milky Way

4636-441: The hadron epoch , and the lepton epoch . Together, these epochs encompassed less than 10 seconds of time following the Big Bang. These elementary particles associated stably into ever larger combinations, including stable protons and neutrons , which then formed more complex atomic nuclei through nuclear fusion . This process, known as Big Bang nucleosynthesis , lasted for about 17 minutes and ended about 20 minutes after

4758-404: The large-scale structure of the universe. Other than neutrinos , a form of hot dark matter , dark matter has not been detected directly, making it one of the greatest mysteries in modern astrophysics . Dark matter neither emits nor absorbs light or any other electromagnetic radiation at any significant level. Dark matter is estimated to constitute 26.8% of the total mass–energy and 84.5% of

4880-421: The observable universe and global geometry . Cosmologists often work with a given space-like slice of spacetime called the comoving coordinates . The section of spacetime which can be observed is the backward light cone , which delimits the cosmological horizon . The cosmological horizon, also called the particle horizon or the light horizon, is the maximum distance from which particles can have traveled to

5002-442: The observer in the age of the universe . This horizon represents the boundary between the observable and the unobservable regions of the universe. An important parameter determining the future evolution of the universe theory is the density parameter , Omega (Ω), defined as the average matter density of the universe divided by a critical value of that density. This selects one of three possible geometries depending on whether Ω

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5124-407: The physical laws that influence energy and matter, such as conservation laws , classical mechanics , and relativity . The universe is often defined as "the totality of existence", or everything that exists, everything that has existed, and everything that will exist. In fact, some philosophers and scientists support the inclusion of ideas and abstract concepts—such as mathematics and logic—in

5246-480: The weak and strong nuclear forces , decline very rapidly with distance; their effects are confined mainly to sub-atomic length scales. The universe appears to have much more matter than antimatter , an asymmetry possibly related to the CP violation . This imbalance between matter and antimatter is partially responsible for the existence of all matter existing today, since matter and antimatter, if equally produced at

5368-536: The Academy collection, and greater in terms of the number of volumes received. The ESL collection added depth to both the journal and monograph collections, containing publications of many engineering societies, including the American Institute of Aeronautics and Astronautics , the American Society of Civil Engineers , American Institute of Chemical Engineers , the American Society of Mechanical Engineers ,

5490-475: The Anaximander tradition give a strong impression of an original and courageous thinker making conscious efforts towards producing a rational explanation of fundamental physical principles, the nature and motion of heavenly bodies, the shape of Earth, its place in the universe, etc. Eastern and Western thought differed greatly in their understanding of space and the organization of the cosmos. The Chinese saw

5612-421: The Big Bang, so only the fastest and simplest reactions occurred. About 25% of the protons and all the neutrons in the universe, by mass, were converted to helium , with small amounts of deuterium (a form of hydrogen ) and traces of lithium . Any other element was only formed in very tiny quantities. The other 75% of the protons remained unaffected, as hydrogen nuclei. After nucleosynthesis ended,

5734-517: The Cosmos as empty, infinite, and intertwined with the Earth. Western ideas, based on the ancient Greeks ' understanding of the cosmos, believed in a multi-planar divided cosmos that was finite and filled with air. Early Europeans viewed the cosmos as a divinely created, spatially finite, bifurcated cosmos, divided into sublunary and superlunary realms. Objects above the lunar disc were believed to be stable, with heavenly bodies believed to be made out of

5856-451: The Earth consisted of condensed yin and the heavens of yang ; and that these properties coexisted in constant relation to each other, with yin and yang being used together to explain processes on Earth as well of those relating the Earth in conjunction with the heavens. This idea was described by Joseph Needham as a cosmos that functioned similarly to a complex organism, with discernible patterns in an ever-changing structure. There

5978-413: The Earth in an epicyclic orbit. Aristotle's geocentric model was also broadly acknowledged, along with his claim that the planets rotated but did not orbit. The reasoning behind this was due to the belief that all objects outside of the lunar sphere were celestial bodies, and therefore could not change, as they were made of quintessence. There were notable critiques of this model prior to Copernicus. In

6100-596: The Elder 's Naturalis Historia ( Natural History ). A number of works can be accessed online, including: The collection includes other important scientific works (many written in Neo-Latin and other languages), including: The 14-acre grounds on which the library sits are home to over 338 trees representing some 52 genera and 145 species. The arboretum and gardens are further embellished by beds of viburnum, tree peonies and Missouri native woodland plants. Seven trees on

6222-541: The Euahlayi saw the Milky Way as a river and between the two bright sides represented a Galactic Bulge where the two sons of the creator Baiame and the river made a connection from the earth and the sky. The Yolngu people were one of the first to discover how the tide of the ocean works. They discovered the tide had a direct correlation with the Moon. Their reasoning as to why the ocean did not fill up as much as perhaps when

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6344-522: The Islamic world, Ibn al-Haytham doubted Ptolemy's notion of the planetary orbits, and Muhammad al-Battani recalculated the parameters. However, both still agreed with the geocentric model. One of the first known astronomers that supported the Heliocentric theory was Aristarchus of Samos . After observing a lunar eclipse , he came to the conclusion that the Sun was farther away from Earth than

6466-480: The Moon and that the Sun was much larger than Earth. He also claimed the Sun was a star. While Aristarchus was later an influence on Copernicus and his groundbreaking work, prior to the 17th century Aristarchus' findings were obstructed by the more established theories of Ptolemy and Aristotle. Astronomer and mathematician Nicolaus Copernicus was appointed by the Catholic Church as an official, as his uncle

6588-426: The Moon beyond these stars, and assumed it to also be wheel-like in shape, being nineteen times the size of Earth. Finally, on the top of the universe is the Sun, which interacts with the Moon, and the relationship between them is described in terms of aperture , in which a stoppage in would lead to eclipses. In this model, the Sun is a ring, 28 times the size of the Earth, with a hollow rim, filled with fire, which at

6710-481: The Moon was full versus a crescent moon is because the Moon was not as full either. This contradicts the father of science, Galileo, who said that the tides correlated with the Earth's orbit around the Sun. Multiple indigenous tribes described winter by the Seven Sisters , a group of stars in the sky that provided hunter-gatherers a sort of calendar to indicate whether they should be hunting or gathering, based on

6832-646: The Moon, stars, and the Sun, this enabled them to create a sense of time. This also allowed them to navigate across the continent, create calendars, and predict the weather. One of the most important constellations in Australia for the Aboriginal people is the Emu. The Emu constellation represents the connection between the earth and the sky, and stories and representations of their constellations were written on some cave walls in Australia. Another indigenous tribe known as

6954-658: The Vedantic text called the Yoga Vāsiṣṭha (YV), which at 32,000 shlokas is one of the longest books in world literature. Australian cosmology has a vast and varied history. Australian cosmology beliefs were based around the Aboriginal and Torres Strait Islander people's ideas, also known as Indigenous astronomy, and it was around before the Babylonians, Greeks, and the Renaissance period. They found ways to observe

7076-435: The belief of a finite universe to an infinite one, which emphasized a more obscure and incomplete version of God. Cosmology is the study of the cosmos, and in its broadest sense covers a variety of very different approaches: scientific, religious and philosophical. All cosmologies have in common an attempt to understand the implicit order within the whole of being. In this way, most religions and philosophical systems have

7198-452: The body so in the universe”. The ancient Indians mapped out the outer world or the universe at an altar where Yajurveda listed multiples of ten that reached ten million. The numbers used to count to ten million was used as a reference to show the relation of the planets in the universe to Earth, it was not a relevant scale to the entire universe, therefore backing that they believed the universe to be infinite and endless. The Indians calculated

7320-484: The chaotic elements of earth, air, fire, and water. The idea of celestial spheres was developed in the cosmological models of Plato , Eudoxus , Aristotle , Ptolemy , Copernicus , and others. They believed in a stable cosmos created by God, where distinct realms were subject to different kinds of order. Some Europeans maintained the Aristotelian view that infinity could only be seen as an attribute of God, with

7442-543: The conception of the first mechanical model of the world, which is outlined by a geocentric model . He postulated that the Earth was at the center of the universe, and that its shape was convex and cylindrical, with life existing on one of the two flat sides. Beyond the Earth, sits the other planets, which Anaximander also details the order of. Next are the fixed stars, which he regarded as wheel-like condensations of air filled with fire, provided at certain places with openings through which flames are discharged. Anaximander places

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7564-447: The cosmos and astrology were viewed. Most notably, Copernicus claimed that the Sun was the stationary center of the universe. His work also included calculations on the motions of the Moon, and the motions in latitude and longitude of the planets, all which orbit the Sun. Copernicus' work was not immediately published as it disagreed with Biblical teachings, and he feared his work would be rejected by Catholic officials. Copernicus' work

7686-472: The cosmos being finite. Furthermore, following the Aristotelian view that "nature abhors a vacuum", some Europeans believed that the space between the spheres were filled with air. This theory persisted until the Scientific Revolution , when the discovery that the Sun was in the center of the planetary system rocked cosmological understanding to its core. Other theories such as Atomism posited

7808-565: The cosmos is the created heavenly bodies (Sun, Moon, wandering stars, and fixed stars ). The concept of cosmos as the created universe and its arrangement has been important in Christendom since its very inception, as it is heavily used in the New Testament and occurs over 180 times. In Christian theology , the word is sometimes used synonymously with aion to refer to "worldly life" or "this world" or "this age" as opposed to

7930-401: The cosmos. This is relatively consistent with the modern understanding of the congregation of matter through gravitational fields. The Chinese held a belief associated with the Xuan Ye theory, which held space as both empty and infinite. This was inconsistent with the Aristotelian concepts that nature would not contain a vacuum, and that infinity could only be a divine attribute. The idea of

8052-510: The definition of the universe. The word universe may also refer to concepts such as the cosmos , the world , and nature . The word universe derives from the Old French word univers , which in turn derives from the Latin word universus , meaning 'combined into one'. The Latin word 'universum' was used by Cicero and later Latin authors in many of the same senses as

8174-546: The density of matter was less than the density of dark energy, marking the beginning of the present dark-energy-dominated era . In this era, the expansion of the universe is accelerating due to dark energy. Of the four fundamental interactions , gravitation is the dominant at astronomical length scales. Gravity's effects are cumulative; by contrast, the effects of positive and negative charges tend to cancel one another, making electromagnetism relatively insignificant on astronomical length scales. The remaining two interactions,

8296-407: The earliest state of the universe was an extremely hot and dense one, and that the universe subsequently expanded and cooled. The model is based on general relativity and on simplifying assumptions such as the homogeneity and isotropy of space. A version of the model with a cosmological constant (Lambda) and cold dark matter , known as the Lambda-CDM model , is the simplest model that provides

8418-423: The early 20th century, the field of cosmology establishes that space and time emerged together at the Big Bang 13.787 ± 0.020 billion years ago and that the universe has been expanding since then. The portion of the universe that we can see is approximately 93 billion light-years in diameter at present, but the total size of the universe is not known. Some of the earliest cosmological models of

8540-411: The energy of each photon decreases as it is cosmologically redshifted . At around 47,000 years, the energy density of matter became larger than that of photons and neutrinos , and began to dominate the large scale behavior of the universe. This marked the end of the radiation-dominated era and the start of the matter-dominated era . In the earliest stages of the universe, tiny fluctuations within

8662-399: The first 10 seconds. This initial period of inflation would explain why space appears to be very flat . Within the first fraction of a second of the universe's existence, the four fundamental forces had separated. As the universe continued to cool from its inconceivably hot state, various types of subatomic particles were able to form in short periods of time known as the quark epoch ,

8784-430: The first time. Unlike plasma, neutral atoms are transparent to many wavelengths of light, so for the first time the universe also became transparent. The photons released (" decoupled ") when these atoms formed can still be seen today; they form the cosmic microwave background (CMB). As the universe expands, the energy density of electromagnetic radiation decreases more quickly than does that of matter because

8906-427: The gradual reionization of the universe between about 200–500 million years and 1 billion years, and also for seeding the universe with elements heavier than helium, through stellar nucleosynthesis . The universe also contains a mysterious energy—possibly a scalar field —called dark energy , the density of which does not change over time. After about 9.8 billion years, the universe had expanded sufficiently so that

9028-523: The largest pieces of malachite in North America, stands as the focal point in the center of the main reading room, which features parquet wood floors, paneling and bookshelves of oak, and large windows that overlook the south lawn. The library's collection numbers over 2 million items. It was initially established by the purchase of the 62,358 books and other items—assembled by John Adams before he became president—that had belonged to

9150-548: The modern English word is used. A term for universe among the ancient Greek philosophers from Pythagoras onwards was τὸ πᾶν ( tò pân ) 'the all', defined as all matter and all space, and τὸ ὅλον ( tò hólon ) 'all things', which did not necessarily include the void. Another synonym was ὁ κόσμος ( ho kósmos ) meaning 'the world , the cosmos '. Synonyms are also found in Latin authors ( totum , mundus , natura ) and survive in modern languages, e.g.,

9272-448: The modern universe. From approximately 10 seconds after the Big Bang , during a period known as the hadron epoch , the temperature of the universe had fallen sufficiently to allow quarks to bind together into hadrons, and the mass of the universe was dominated by hadrons . Initially, the temperature was high enough to allow the formation of hadron–anti-hadron pairs, which kept matter and antimatter in thermal equilibrium . However, as

9394-408: The nature of the universe, a theory or doctrine describing the natural order of the universe. The basic definition of Cosmology is the science of the origin and development of the universe. In modern astronomy, the Big Bang theory is the dominant postulation. Philosophy of cosmology is an expanding discipline, directed to the conceptual foundations of cosmology and the philosophical contemplation of

9516-541: The next heavier element, carbon , was not formed in significant amounts. Big Bang nucleosynthesis shut down after about 20 minutes due to the rapid drop in temperature and density of the expanding universe. Subsequent formation of heavier elements resulted from stellar nucleosynthesis and supernova nucleosynthesis . Ordinary matter and the forces that act on matter can be described in terms of elementary particles . These particles are sometimes described as being fundamental, since they have an unknown substructure, and it

9638-560: The nothingness of space was later recognized as one of the most important discoveries of modern science. The Indians believed in a cyclic universe related to three other beliefs: (i), time is endless and space has infinite extension; (ii), earth is not the center of the universe; and (iii), laws govern all development, including the creation and destruction of the universe. The Indians believed that there were three types of space, physiological, physical, and infinite space. The infinite space consists of undivided consciousness and everything that

9760-518: The observed rate of expansion. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant can be formulated to be equivalent to vacuum energy . Dark matter is a hypothetical kind of matter that is invisible to the entire electromagnetic spectrum , but which accounts for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, radiation, and

9882-428: The other fundamental forces, and all the forces may have been unified . The physics controlling this very early period (including quantum gravity in the Planck epoch) is not understood, so we cannot say what, if anything, happened before time zero . Since the Planck epoch, the universe has been expanding to its present scale, with a very short but intense period of cosmic inflation speculated to have occurred within

10004-439: The overall current view of the universe , in the form of the Standard Model of Cosmology , based on the latest James Webb Space Telescope studies. In October 2023, astronomers proposed a new, more comprehensive, view of the cosmos, and which includes all objects in the universe, and suggested that the universe may have begun with instantons , and may be a black hole . Cosmology is a branch of metaphysics that deals with

10126-407: The physical universe. The verb κοσμεῖν ( κοσμεῖν ) meant generally "to dispose, prepare", but especially "to order and arrange (troops for battle), to set (an army) in array"; also "to establish (a government or regime)", "to adorn, dress" (especially of women). Thus kosmos meant "ornaments, decoration" (compare kosmokomes "dressing the hair," and cosmetic). The philosopher Pythagoras used

10248-442: The possibilities that the universe has more dimensions (which is postulated by theories such as string theory) and that its spacetime may have a multiply connected global topology, in analogy with the cylindrical or toroidal topologies of two-dimensional spaces . General relativity describes how spacetime is curved and bent by mass and energy (gravity). The topology or geometry of the universe includes both local geometry in

10370-458: The presence of other masses. A remark by John Archibald Wheeler that has become proverbial among physicists summarizes the theory: "Spacetime tells matter how to move; matter tells spacetime how to curve", and therefore there is no point in considering one without the other. The Newtonian theory of gravity is a good approximation to the predictions of general relativity when gravitational effects are weak and objects are moving slowly compared to

10492-408: The present dark-energy era, it dominates the mass–energy of the universe because it is uniform across space. Two proposed forms for dark energy are the cosmological constant , a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli , dynamic quantities whose energy density can vary in time and space while still permeating them enough to cause

10614-463: The property have been designated Greater Kansas City Champion Trees and represent the largest specimens of their species in the metropolitan area: Sweet Birch, European Hornbeam, Hardy Rubber Tree, Double Flowered Horsechestnut, Rivers Purple Beech, Yulan Magnolia, and Anise Leaf Magnolia. Cosmos The cosmos ( Ancient Greek : κόσμος , romanized :  Kósmos , / ˈ k ɒ z m ɒ s / , US also /- m oʊ s , - m ə s / )

10736-498: The realization that the Sun is one of a few hundred billion stars in the Milky Way , which is one of a few hundred billion galaxies in the observable universe. Many of the stars in a galaxy have planets . At the largest scale , galaxies are distributed uniformly and the same in all directions, meaning that the universe has neither an edge nor a center. At smaller scales, galaxies are distributed in clusters and superclusters which form immense filaments and voids in space, creating

10858-456: The same from all vantage points and has no center. An explanation for why the expansion of the universe is accelerating remains elusive. It is often attributed to the gravitational influence of "dark energy", an unknown form of energy that is hypothesized to permeate space. On a mass–energy equivalence basis, the density of dark energy (~ 7 × 10 g/cm ) is much less than the density of ordinary matter or dark matter within galaxies. However, in

10980-456: The same time, a second observer who is moving relative to the first will see those events happening at different times. The two observers will disagree on the time T {\displaystyle T} between the events, and they will disagree about the distance D {\displaystyle D} separating the events, but they will agree on the speed of light c {\displaystyle c} , and they will measure

11102-477: The same value for the combination c 2 T 2 − D 2 {\displaystyle c^{2}T^{2}-D^{2}} . The square root of the absolute value of this quantity is called the interval between the two events. The interval expresses how widely separated events are, not just in space or in time, but in the combined setting of spacetime. The special theory of relativity cannot account for gravity . Its successor,

11224-541: The science, technology, and engineering disciplines." The library's William N. Deramus III Cosmology Theater, temporarily closed since 2020, shows images of the cosmos from the Hubble Space Telescope and NASA science missions. These images are delivered via ViewSpace to the library with daily updates (via the Internet) that provide the library with new content for visitors. "The Tazza ", one of

11346-528: The season. There is one way that both the Chinese and the Europeans, along with countless other ancient societies, related to the cosmos. This was through meaning, placed on celestial bodies, that were observed moving above the Earth. The Chinese had a very complex astronomical understanding of the stars and the cosmos that influenced everything from their art and architecture to their myths and science. This

11468-401: The second derivative of the cosmic scale factor a ¨ {\displaystyle {\ddot {a}}} has been positive in the last 5–6 billion years. Modern physics regards events as being organized into spacetime . This idea originated with the special theory of relativity , which predicts that if one observer sees two events happening in different places at

11590-472: The speed of light to be four thousand four hundred and four (4,404) yojanas per nimesa, or about one hundred eighty six thousand (186,000) miles per second. Ancient Indian beliefs also included the belief that the Earth was created after certain stars, these stars include the Sun, Gemini, Aja, and Kurma. Evidence from the Etymological considerations prove this belief and also points towards the discovery of

11712-414: The speed of light, 13.8 billion light-years (4.2 × 10 ^  pc), the proper distance is larger because the edge of the observable universe and the Earth have since moved further apart. For comparison, the diameter of a typical galaxy is 30,000 light-years (9,198 parsecs ), and the typical distance between two neighboring galaxies is 3 million light-years (919.8 kiloparsecs). As an example,

11834-454: The speed of light. The relation between matter distribution and spacetime curvature is given by the Einstein field equations , which require tensor calculus to express. The universe appears to be a smooth spacetime continuum consisting of three spatial dimensions and one temporal ( time ) dimension. Therefore, an event in the spacetime of the physical universe can be identified by

11956-483: The standard model of cosmology, describing a flat , homogeneous universe presently dominated by dark matter and dark energy . The fine-tuned universe hypothesis is the proposition that the conditions that allow the existence of observable life in the universe can only occur when certain universal fundamental physical constants lie within a very narrow range of values. According to this hypothesis, if any of several fundamental constants were only slightly different,

12078-433: The statistical properties of the universe are the same in all directions as observed from Earth. The universe is bathed in highly isotropic microwave radiation that corresponds to a thermal equilibrium blackbody spectrum of roughly 2.72548 kelvins . The hypothesis that the large-scale universe is homogeneous and isotropic is known as the cosmological principle . A universe that is both homogeneous and isotropic looks

12200-404: The temperature of the universe continued to fall, hadron–anti-hadron pairs were no longer produced. Most of the hadrons and anti-hadrons were then eliminated in particle–antiparticle annihilation reactions, leaving a small residual of hadrons by the time the universe was about one second old. A lepton is an elementary , half-integer spin particle that does not undergo strong interactions but

12322-857: The term cosmos is often used in a technical way, referring to a particular spacetime continuum within a (postulated) multiverse . The particular cosmos in which humans live, the observable universe , is generally capitalized as the Cosmos . In physical cosmology, the uncapitalized term cosmic signifies a subject with a relationship to the universe, such as 'cosmic time' (time since the Big Bang ), ' cosmic rays ' (high energy particles or radiation detected from space ), and ' cosmic microwave background ' (microwave radiation detectable from all directions in space). According to Charles Peter Mason in Sir William Smith Dictionary of Greek and Roman Biography and Mythology (1870, see book screenshot for full quote), Pythagoreans described

12444-633: The term kosmos ( Ancient Greek : κόσμος , Latinized kósmos ) for the order of the universe. Anaxagoras further introduced the concept of a Cosmic Mind ( Nous ) ordering all things. The modern Greek κόσμος "order, good order, orderly arrangement" is a word with several main senses rooted in those notions. κόσμος has developed, along with primary "the universe, the world", the meaning of "people" (collectively). The 1870 book Dictionary of Greek and Roman Biography and Mythology noted The book The Works of Aristotle (1908, p. 80 Fragments ) mentioned Bertrand Russell (1947) noted Anaximander

12566-476: The total matter in the universe. The remaining 4.9% of the mass–energy of the universe is ordinary matter, that is, atoms , ions , electrons and the objects they form. This matter includes stars , which produce nearly all of the light we see from galaxies, as well as interstellar gas in the interstellar and intergalactic media, planets , and all the objects from everyday life that we can bump into, touch or squeeze. The great majority of ordinary matter in

12688-609: The twin asses, which in western astrology can be found next to the Cancer constellation as Asellus, Borealis, and Asellus Australis. The Indian cyclic model assumes the existence of countless island universes, which go through their own periods of development and destruction. The conception of cyclicity is taken to be recursive. For an early exposition of these astronomical and cosmological ideas, one may read al-Bīrūnī's classic history of Indian science, composed in 1030 AD, and for an even earlier, popular, view of Indian ideas, one may consult

12810-401: The universe as a totality. It draws on the fundamental theories of physics – thermodynamics, statistical mechanics, quantum mechanics, quantum field theory, and special and general relativity – and on several branches of philosophy – philosophy of physics, philosophy of science, metaphysics, philosophy of mathematics, and epistemology. In theology ,

12932-488: The universe entered a period known as the photon epoch . During this period, the universe was still far too hot for matter to form neutral atoms , so it contained a hot, dense, foggy plasma of negatively charged electrons , neutral neutrinos and positive nuclei. After about 377,000 years, the universe had cooled enough that electrons and nuclei could form the first stable atoms . This is known as recombination for historical reasons; electrons and nuclei were combining for

13054-437: The universe gradually cooled and continued to expand, allowing the first subatomic particles and simple atoms to form. Giant clouds of hydrogen and helium were gradually drawn to the places where matter was most dense , forming the first galaxies, stars, and everything else seen today. From studying the effects of gravity on both matter and light, it has been discovered that the universe contains much more matter than

13176-454: The universe has decreased by 1/2 in the past 2 billion years. Today, ordinary matter, which includes atoms, stars, galaxies, and life , accounts for only 4.9% of the contents of the universe. The present overall density of this type of matter is very low, roughly 4.5 × 10 grams per cubic centimeter, corresponding to a density of the order of only one proton for every four cubic meters of volume. The nature of both dark energy and dark matter

13298-406: The universe has expanded monotonically . Perhaps unsurprisingly , our universe has just the right mass–energy density , equivalent to about 5 protons per cubic meter, which has allowed it to expand for the last 13.8 billion years, giving time to form the universe as observed today. There are dynamical forces acting on the particles in the universe which affect the expansion rate. Before 1998, it

13420-482: The universe is unseen, since visible stars and gas inside galaxies and clusters account for less than 10 percent of the ordinary matter contribution to the mass–energy density of the universe. Ordinary matter commonly exists in four states (or phases ): solid , liquid , gas , and plasma . However, advances in experimental techniques have revealed other previously theoretical phases, such as Bose–Einstein condensates and fermionic condensates . Ordinary matter

13542-401: The universe might be one among many. The physical universe is defined as all of space and time (collectively referred to as spacetime ) and their contents. Such contents comprise all of energy in its various forms, including electromagnetic radiation and matter , and therefore planets, moons , stars, galaxies, and the contents of intergalactic space . The universe also includes

13664-638: The universe were developed by ancient Greek and Indian philosophers and were geocentric , placing Earth at the center. Over the centuries, more precise astronomical observations led Nicolaus Copernicus to develop the heliocentric model with the Sun at the center of the Solar System . In developing the law of universal gravitation , Isaac Newton built upon Copernicus's work as well as Johannes Kepler 's laws of planetary motion and observations by Tycho Brahe . Further observational improvements led to

13786-422: The universe would have been unlikely to be conducive to the establishment and development of matter , astronomical structures, elemental diversity, or life as it is understood. Whether this is true, and whether that question is even logically meaningful to ask, are subjects of much debate. The proposition is discussed among philosophers , scientists , theologians , and proponents of creationism . The universe

13908-467: The universe's density led to concentrations of dark matter gradually forming. Ordinary matter, attracted to these by gravity , formed large gas clouds and eventually, stars and galaxies, where the dark matter was most dense, and voids where it was least dense. After around 100–300 million years, the first stars formed, known as Population III stars. These were probably very massive, luminous, non metallic and short-lived. They were responsible for

14030-480: The universe. It appears, in fact, from this, as well as from the extant fragments, that the first book (from Philolaus ) of the work contained a general account of the origin and arrangement of the universe. The second book appears to have been an exposition of the nature of numbers, which in the Pythagorean theory are the essence and source of all things. (p. 305) In September 2023, astrophysicists questioned

14152-434: The universe. Stars, planets, and visible gas clouds only form about 6% of this ordinary matter. There are many competing hypotheses about the ultimate fate of the universe and about what, if anything, preceded the Big Bang, while other physicists and philosophers refuse to speculate, doubting that information about prior states will ever be accessible. Some physicists have suggested various multiverse hypotheses, in which

14274-513: Was a bishop in the church. He used his income to further his studies, eventually studying at the University of Bologna in Italy. Copernicus began doubting the knowledge of natural philosophers and their beliefs, claiming that geometrical astronomy instead would result in the true reality of the cosmos. His manuscript, De revolutionibus , pioneered ideas that would change the course of how both

14396-483: Was a pre- Socratic Greek philosopher who is widely referred to as the "father of astronomy" and even as the "father of cosmology" as a result of his works to explain the origin and makeup of the physical universe. He is regarded as the most important of the Ionian philosophers, and was a pupil of Thales . Traditionally, details of his life and opinions are perpetuated not only by Aristotle and Theophrastos , but also by

14518-452: Was also true of the Greeks and Romans, whose 48 constellations, including the zodiac signs and the constellation of Orion, have been passed down to modern Western cultures. These were likely passed down to them from ancient Babylonian and Egyptian astronomers. Copernicus is said to have been inspired by the fecund sun deity of neoplatonic thought, which may have initially inspired his vision of

14640-414: Was both a pattern and a randomness to the cosmos. Because of this, the Chinese believed that earthly phenomena could affect heavenly bodies. The Chinese believed that qi was the substance of all things in the cosmos and Earth, including inanimate matter, humans, ideas, emotions, celestial bodies and everything that exists or has existed; and that it was qi condensing that created all the matter within

14762-485: Was expected that the expansion rate would be decreasing as time went on due to the influence of gravitational interactions in the universe; and thus there is an additional observable quantity in the universe called the deceleration parameter , which most cosmologists expected to be positive and related to the matter density of the universe. In 1998, the deceleration parameter was measured by two different groups to be negative, approximately −0.55, which technically implies that

14884-452: Was not entirely mathematical conviction. There is evidence that Copernicus was influenced by neoplatonism . Founded by philosopher Plotinus , neoplatonism believes that the Sun is the symbol of The One, or The Universal Soul . It would make sense then that Copernicus would place the god-like figure at the center of the universe. Neoplatonist Nicholas of Cusa claimed the universe was infinite, containing multiple earths and suns. This changed

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