المعرفة

علم الكون

علم الكون أو الكوسمولوجيا هو العلم الذي يدرس الكون بمجمله بكل ما فيه من مادة وطاقة كمكان يعيش به الإنسان و يتفاعل معه.

هبل - مجرة ناشئة

تأتي كلمة كوسمولوجيا من الكلمة الإغريقية : κόσμος (cosmos) وتعني الكون واللاحقة λογια (logia) بمعنى خطبة أو محاضرة وهي تلحق بمعظم الكلمات لتشير إلى العلم الذي يدرس هذا الموضوع. ورغم حداثة هذا العلم من حيث تداخله مع الفيزياء الحديثة فإن جذوره تمتد إلى العصور القديمة بمعالجاتها الفلسفية والدينية الغيبية (ميتافيزيقية) لموضوع أصل الكون و الوجود.

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المجالات

ويوجد العديد من النسخ التاريخية لعلم الكون:

"... يعمل الكون نفسه علينا كآلة تعليمية عشوائية، غير فعالة، إلا أنها على المدى البعيد فعالة. ...وقد تحورت تدريجياً طريقتنا في النظر إلى الكون عبر انتقاء طبيعي للأفكار." —ستيڤن واينبرگ[1]


علم الكون على مر التاريخ

للمزيد من المعلومات: خط زمني لعلم الكون
الاسم المؤلف والتاريخ التصنيف تعليقات
علم الكون البابلي الأدب البابلي (1900-1200 ق.م.) Plurality of heavens and earths الأرض والسماء يشكلان "spatial whole, even one of شكل مستدير،" revolving around the "cult-place of the deity" rather than the Earth,[2] and there is a plurality of heavens and earths.[3]
براهماندا (علم الكون الهندوسي) ريگڤـِدا هندوسية (1700–1100 ق.م.) Cyclical or oscillating, Infinite in time The universe sustains for around 311 trillion and 40 billion years that is 100 years of the cosmic creator Brahma. There is a smaller period of unmanifestation in around 4 billion years that is one day in the life of Brahma. The universe cycles between expansion and total collapse. After one cycle of the life of Brahma another universe follows up to an infinite number each of which exists for a time period of 311 trillion and 40 billion years. It also speaks of an infinite number of universes at one given point of time. Universe expanded from a concentrated form —a point called a Bindu. The universe, as a living entity, is bound to the perpetual دورة الميلاد، الموت واعادة الميلاد.
Atomist universe أناكساگوراس (500-428 ق.م.) & ولاحقاً إپيقور Infinite in extent The universe contains only two things: an infinite number of tiny seeds, or atoms, and the void of infinite extent. All atoms are made of the same substance, but differ in size and shape. Objects are formed from atom aggregations and decay back into atoms. Incorporates ليوكيپوس' principle of السببية: "nothing happens at random; everything happens out of reason and necessity." The universe was not ruled by gods.
الكون الفيثاغوري فيلولاوس (ت. 390 ق.م.) Existence of a "Central Fire" at the center of the Universe. At the center of the Universe is a central fire, around which the Earth, Sun, Moon and Planets revolve uniformly. The sun revolves around the central fire once a year, the stars are immobile. The earth in its motion maintains the same hidden face towards the central fire, hence it is never seen. This is the first known non-geocentric model of the Universe.[4]
Stoic universe Stoics (300 B.C. - 200 A.D.) Island universe The cosmos is finite and surrounded by an infinite void. It is in a state of flux, as it pulsates in size and periodically passes through upheavals and conflagrations.
الكون الأرسطوطلي أرسطو (384-322 B.C.) Geocentric, static, steady state, finite extent, infinite time Spherical earth is surrounded by concentric celestial spheres. Universe exists unchanged throughout eternity. Contains a 5th element called aether (later known as quintessence).
Aristarchean universe Aristarchus (circa 280 B.C.) Heliocentric Earth rotates daily on its axis and revolves annually about the sun in a circular orbit. Sphere of fixed stars is centered about the sun.
الكون السلوقي سلوقس من سلوقيا (حوالي 190 ق.م.) متمركز حول الشمس Modifications to the Aristarchean universe, with the inclusion of the tide phenomenon to explain heliocentrism.
النموذج البطلمي (based on Aristotelian universe) بطليموس (القرن الثاني الميلادي) متمركز حول الأرض Universe orbits about a stationary Earth. Planets move in circular epicycles, each having a center that moved in a larger circular orbit (called an eccentric or a deferent) around a center-point near the Earth. The use of equants added another level of complexity and allowed astronomers to predict the positions of the planets. The most successful universe model of all time, using the criterion of longevity. المجسطي (النظام الأعظم).
نموذج أريابهاتا أريابهاتا (499) Geocentric or Heliocentric The Earth rotates and the planets move in elliptical orbits, possibly around either the Earth or the Sun. It is uncertain whether the model is geocentric or heliocentric due to planetary orbits given with respect to both the Earth and the Sun.
الكون الابراهيمي فلاسفة القرون الوسطى (500-1200) Finite in time The universe that is finite in time and has a beginning is proposed by the الفيلسوف المسيحي, يوحنا فيلوپونوس, who argues against the ancient Greek notion of an infinite past. Logical arguments supporting a finite universe are developed by the الفيلسوف المسلم المبكر، الكندي; the الفيلسوف اليهودي، سعديا گاعون؛ والمتكلمة، الغزالي.
Multiversal cosmology Fakhr al-Din al-Razi (1149–1209) Multiverse, multiple worlds & universes There exists an infinite outer space beyond the known world, and God has the power to fill the vacuum with an infinite number of universes.
نماذج المراغة مدرسة المراغة (1259–1528) متمركز حول الأرض Various modifications to Ptolemaic model and Aristotelian universe, including rejection of equant and eccentrics at Maragheh observatory, and introduction of Tusi-couple by Al-Tusi. Alternative models later proposed, including the first accurate lunar model by Ibn al-Shatir, a model rejecting stationery Earth in favour of Earth's rotation by Ali Kuşçu, and planetary model incorporating "circular inertia" by البرجندي.
نموذج نيلاكانثا نيلاكانثا سوماياجي (1444–1544) Geocentric and Heliocentric A universe in which the planets orbit the Sun and the Sun orbits the Earth, similar to the later Tychonic system.
الكون الكوپرنيقي نيكولاوس كوپرنيكوس (1543) Heliocentric نموذج المراغة المتمركز حول الأرض لابن الشاطر adapted to meet the requirements of the ancient heliocentric Aristarchean universe in his De revolutionibus orbium coelestium.
نظام تيخو تيخو براهه (1546–1601) Geocentric and Heliocentric A universe in which the planets orbit the Sun and the Sun orbits the Earth, similar to the earlier نموذج نيلاكانثا.
نيوتوني استاتيكي السير إسحق نيوتن (1642–1727) Static (evolving), steady state, infinite Every particle in the universe attracts every other particle. Matter on the large scale is uniformly distributed. Gravitationally balanced but unstable.
Cartesian Vortex universe رينيه ديكارت

17th century

Static (evolving), steady state, infinite A system of huge swirling whirlpools of aethereal or fine matter produces what we would call gravitational effects. His vacuum was not empty. All space was filled with matter that swirled around in large and small vortices.
كون هيراركي إيمانويل كانت، يوهان لامبرت القرن 18 Static (evolving), steady state, infinite Matter is clustered on ever larger scales of hierarchy. Matter is endlessly being recycled.
Einstein Universe with a cosmological constant ألبرت أينشتاين 1917 Static (nominally). Bounded (finite) "Matter without motion." Contains uniformly distributed matter. Uniformly curved spherical space; based on Riemann's hypersphere. Curvature is set equal to Λ. In effect Λ is equivalent to a repulsive force which counteracts gravity. Unstable.
كون ده سيتر ڤيلم ده سيتر 1917 فضاء مسطح متمدد.

Steady state. Λ > 0

"Motion without matter." Only apparently static. Based on Einstein's النسبية العامة. Space expands with constant acceleration. Scale factor (radius of universe) increases exponentially, i.e. constant inflation.
كون مكميلان وليام دنكان مكميلان ع1920 Static &

steady state

New matter is created from radiation. Starlight is perpetually recycled into new matter particles.
كون فريدمان من الفضاء الكروي ألكسندر فريدمان 1922 Spherical expanding space.

k= +1 ; no Λ

Positive curvature. Curvature constant k = +1

Expands then recollapses. Spatially closed (finite).

كون فريدمان of hyperbolic space ألكسندر فريدمان 1924 Hyperbolic expanding space.

k= -1 ; no Λ

Negative curvature. Said to be infinite (but ambiguous). Unbounded. Expands forever.
فرضية ديراك للأرقام الكبيرة پول ديراك 1930s متمدد Demands a large variation in G, which decreases with time. Gravity weakens as universe evolves.
Friedmann zero-curvature, a.k.a. the Einstein-DeSitter universe أينشتاين وده سيتر 1932 فضاء مسطح متمدد.

k= 0 ; Λ = 0 Critical density

Curvature constant k = 0. Said to be infinite (but ambiguous). 'Unbounded cosmos of limited extent.' Expands forever. 'Simplest' of all known universes. Named after but not considered by Friedmann. Has a deceleration term q =½ which means that its expansion rate slows down.
جورج لميتر

the original Big Bang. a.k.a. Friedmann-Lemaître Model

جورج لميتر 1927-29 تمدد

Λ > 0 Λ > |Gravity|

Λ is positive and has a magnitude greater than Gravity. Universe has initial high density state ('primeval atom'). Followed by a two stage expansion. Λ is used to destabilize the universe. (Lemaître is considered to be the father of the big bang model.)
الكون المتأرجح

(a.k.a. Friedmann-Einstein; was latter's 1st choice after rejecting his own 1917 model)

Favored by Friedmann

1920s

Expanding and contracting in cycles Time is endless and beginningless; thus avoids the beginning-of-time paradox. Perpetual cycles of big bang followed by big crunch.
إدنگتن آرثر إدنگتن 1930 كان استاتيكياً

ثم تمدد

Static Einstein 1917 universe with its instability disturbed into expansion mode; with relentless matter dilution becomes a DeSitter universe. Λ dominates gravity.
كون ميلن من النسبية التحريكية إدوارد ميلن, 1933, 1935;

وليام مكري، 1930s

تمدد تحريكي بدون تمدد الفضاء Rejects general relativity and the expanding space paradigm. Gravity not included as initial assumption. Obeys cosmological principle & rules of special relativity. The Milne expanding universe consists of a finite spherical cloud of particles (or galaxies) that expands WITHIN flat space which is infinite and otherwise empty. It has a center and a cosmic edge (the surface of the particle cloud) which expands at light speed. His explanation of gravity was elaborate and unconvincing. For instance, his universe has an infinite number of particles, hence infinite mass, within a finite cosmic volume.
Friedmann-Lemaître-Robertson-Walker class of models هوارد روبرتسون, آرثر واكر، 1935 يتمدد بانتظام Class of universes that are homogenous and isotropic. Spacetime separates into uniformly curved space and cosmic time common to all comoving observers. The formulation system is now known as the FLRW or Robertson-Walker metrics of cosmic time and curved space.
Steady-state expanding (Bondi & Gold) هرمان بوندي، توماس گولد 1948 Expanding, steady state, infinite Matter creation rate maintains constant density. Continuous creation out of nothing from nowhere. Exponential expansion. Deceleration term q = -1.
Steady-state expanding (Hoyle) فرد هويل 1948 Expanding, steady state; but unstable Matter creation rate maintains constant density. But since matter creation rate must be exactly balanced with the space expansion rate the system is unstable.
Ambiplasma هانس ألفڤين 1965 اوسكار كلاين Cellular universe, expanding by means of matter-antimatter annihilation Based on the concept of علم الفلك البلازمي. The universe is viewed as meta-galaxies divided by double layers —hence its bubble-like nature. Other universes are formed from other bubbles. Ongoing cosmic matter-antimatter annihilations keep the bubbles separated and moving apart preventing them from interacting.
برانز-ديك كارل برانز; روبرت ديك متمدد مبني على مبدأ ماخ. G varies with time as universe expands. "But nobody is quite sure what Mach's principle actually means."
تضخم كوني ألان گوث 1980 Big Bang with modification to solve horizon problem and flatness problem. Based on the concept of hot inflation. The universe is viewed as a multiple quantum flux —hence its bubble-like nature. Other universes are formed from other bubbles. Ongoing cosmic expansion kept the bubbles separated and moving apart preventing them from interacting.
Eternal Inflation (a multiple universe model) أندري لينده 1983 Big Bang with تمدد كوني A multiverse, based on the concept of cold inflation, in which inflationary events occur at random each with independent initial conditions; some expand into bubble universes supposedly like our entire cosmos. Bubbles nucleate in a spacetime foam.
النموذج الدوري پول شتاينهارد; نيل توروك 2002 Expanding and contracting in cycles; M theory. Two parallel orbifold planes or M-branes collide periodically in a higher dimensional space. With quintessence or الطاقة الداكنة
النموذج الدوري لوريس باوم؛ پول فرامپتون 2007 حل مشكلة الإنتروبية لتولمان Phantom dark energy fragments universe

into large number of disconnected patches. Our patch contracts containing only dark energy with zero entropy.

ملاحظة على الجدول: المصطلح "استاتيكي" ببساطة يعني ليس متمدداً وليس منكمشاً. الرمز G يمثل ثابت الجاذبية لنيوتن؛ و(لامبدا) هي الثابت الكوني.

علم الكون الفيزيائي


علم الكون الميتافيزيقي


ملف:The origin.swf

ملف:The ORIGIN.flv


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انظر أيضا

ملاحظات و مراجع

  1. ^ Weinberg, p158.
  2. ^ Norriss S. Hetherington (1993), Cosmology: historical, literary, philosophical, religious, and scientific perspectives, Taylor & Francis, p. 46, ISBN 0815309341 
  3. ^ Norriss S. Hetherington (1993), Cosmology: historical, literary, philosophical, religious, and scientific perspectives, Taylor & Francis, p. 44, ISBN 0815309341 
  4. ^ Boyer, C. A History of Mathematics. Wiley, p. 54.

قراءات إضافية

  • Landau, Lev, Lifshitz, E.M. (1975). The Classical Theory of Fields (Course of Theoretical Physics, Vol. 2) (revised 4th English ed.). New York: Pergamon Press. pp. 358–397. ISBN 9780080181769.{{cite book}}: CS1 maint: multiple names: authors list (link)
  • Misner, C.W.,Thorne, Kip, Wheeler, J.A. (1973). Gravitation. San Francisco: W. H. Freeman. pp. 703–816. ISBN 978-0-7167-0344-0.{{cite book}}: CS1 maint: multiple names: authors list (link) The classic text for a generation.
  • Rindler, W. (1977). Essential Relativity: Special, General, and Cosmological. New York: Springer Verlag. pp. 193–244. ISBN 0-387-10090-3.
  • Weinberg, S. (1972). Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity. New York: John Wiley and Sons. pp. 407–633. ISBN 0-471-92567-5.
  • Weinberg, S. (1993). The First Three Minutes: A Modern View of the Origin of the Universe (2nd updated ed.). New York: Basic Books. ISBN 978-0465024377. OCLC 28746057.

الروابط الخارجية

 
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