قانون هبل

تلسكوب مرصد مونت ويلسون الذي استخدمه إدوين هابل لرصد المجرات، وقاده لصياغة القانون المعروف باسمه.
تطور نشأة الكون حتى الآن (توضيح بمقياس رسم اختياري لتمدد الكون ، الثانية 0 إلى اليسار).

قانون هبل Hubble's law أو قانون لومتر Lemaître's law، هو اسم نظرية في علم الكون الفيزيائي (تم إثباتها بالرصد)، وتنص على أن السرعة التي تبتعد بها مجرة من المجرات عنا تتناسب تناسبا طرديا مع المسافة بينها وبين الأرض. [1] وقد استنبط الفيزيائي والقسيس في نفس الوقت جورج لومتر هذا القانون عن طريق حله ل النظرية النسبية العامة لأينشتاين عام 1927. [2] ثم تبعه إدوين هابل عام 1929 وصاغ مثيلا لهذا القانون عن طريق القياس العملي لسرعة المجرات وسمي القانون باسمه "قانون هابل" حيث أنه يستند إلى قياسات عملية. [3] وذلك بعد عدة سنوات من الرصد وتسجيل القياسات، وقد استنتجت سرعة ابتعاد المجرات عنا عن طريق قياس مقدار الانزياح الأحمر الذي نجده عند قياس أطياف تلك المجرات. [4] وهي تعتبر أول مشاهدة تعتمد على المشاهدة العملية عن طريق التلسكوبات والتي تبين أن الكون يتمدد وهي أحد الإثباتات المعترف بها في وقتنا الحاضر لحدوث الانفجار العظيم منذ نحو 13.7 مليار سنة ونشأة الكون.

تطورت نظرية الانفجار العظيم من ملاحظات واعتبارات نظرية. الملاحظات الأولى كانت واضحة منذ زمن وهي أن السدم اللولبية تبتعد عن الأرض، لكن من سجل هذه الملاحظات لم يذهب بعيدا في تحليل هذه النتائج. في عام 1927 قام الكاهن البلجيكي جورج لومتر باشتقاق معادلات فريدمان-ليمايتري-روبرتسون-ووكر انطلاقا من النظرية النسبية العامة لأينشتاين واستنتج بناء على ظاهرة استمرار السدم الحلزونية في الابتهاد عن مجرتنا، مجرة درب التبانة أن الكون لابد وأن يكون قد بدأ من انفجار ذرة بدئية، وهذا ما دعي لاحقا في الأوساط العلمية ب الانفجار العظيم.

وفي عام 1929، أثبت إدوين هابل نظرية لومتر بإعطاء دليل رصدي للنظرية. اكتشف هابل أن المجرات تبتعد بعيدا من الأرض في جميع الاتجاهات وبسرعة تتناسب طرديا مع بعدها عن الأرض. هذا ما عـُرف لاحقا باسم قانون هابل. حسب المبدأ الكوني فإن الكون لا يملك إتجاها مفضلا ولا مكانا مفضلا لذلك كان استنتاج هابل أن الكون يتمدد بشكل معاكس تماما لتصور أينشتاين الذي كان يعتقد في كون ساكن.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

الاكتشاف

Three steps to the Hubble constant[5]

A decade before Hubble made his observations, a number of physicists and mathematicians had established a consistent theory of an expanding universe by using Einstein's field equations of general relativity. Applying the most general principles to the nature of the universe yielded a dynamic solution that conflicted with the then-prevalent notion of a static universe.


معادلات فريدمان

شكل الكون

نجوم المتغير السيفاوي خارج درب التبانة

الجمع بين الانيزاح الأحمر وقياسات المسافة

Fit of redshift velocities to Hubble's law; patterned after William C. Keel (2007). The Road to Galaxy Formation. Berlin: Springer published in association with Praxis Pub., Chichester, UK. ISBN 3-540-72534-2.Various estimates for the Hubble constant exist. The HST Key H0 Group fitted type Ia supernovae for redshifts between 0.01 and 0.1 to find that H0 = 71 ± 2(statistical) ± 6 (systematic) km s−1Mpc−1,[6] while Sandage et al. find H0 = 62.3 ± 1.3 (statistical) ± 5 (systematic) km s−1Mpc−1.[7]


مخطط هبل

التخلي عن الثابت الكوني

After Hubble's discovery was published, Albert Einstein abandoned his work on the cosmological constant, which he had designed to modify his equations of general relativity to allow them to produce a static solution, which he thought was the correct state of the universe. The Einstein equations in their simplest form model generally either an expanding or contracting universe, so Einstein's cosmological constant was artificially created to counter the expansion or contraction to get a perfect static and flat universe.[8] After Hubble's discovery that the universe was, in fact, expanding, Einstein called his faulty assumption that the universe is static his "biggest mistake".[8] On its own, general relativity could predict the expansion of the universe, which (through observations such as the bending of light by large masses, or the precession of the orbit of Mercury) could be experimentally observed and compared to his theoretical calculations using particular solutions of the equations he had originally formulated.

In 1931, Einstein made a trip to Mount Wilson Observatory to thank Hubble for providing the observational basis for modern cosmology.[9]

The cosmological constant has regained attention in recent decades as a hypothesis for dark energy.[10]

التفسير

A variety of possible recessional velocity vs. redshift functions including the simple linear relation v = cz; a variety of possible shapes from theories related to general relativity; and a curve that does not permit speeds faster than light in accordance with special relativity. All curves are linear at low redshifts. See Davis and Lineweaver.[11]

The discovery of the linear relationship between redshift and distance, coupled with a supposed linear relation between recessional velocity and redshift, yields a straightforward mathematical expression for Hubble's law as follows:

where

  • is the recessional velocity, typically expressed in km/s.
  • H0 is Hubble's constant and corresponds to the value of (often termed the Hubble parameter which is a value that is time dependent and which can be expressed in terms of the scale factor) in the Friedmann equations taken at the time of observation denoted by the subscript 0. This value is the same throughout the universe for a given comoving time.
  • is the proper distance (which can change over time, unlike the comoving distance, which is constant) from the galaxy to the observer, measured in mega parsecs (Mpc), in the 3-space defined by given cosmological time. (Recession velocity is just v = dD/dt).

Hubble's law is considered a fundamental relation between recessional velocity and distance. However, the relation between recessional velocity and redshift depends on the cosmological model adopted and is not established except for small redshifts.

For distances D larger than the radius of the Hubble sphere rHS , objects recede at a rate faster than the speed of light (See Uses of the proper distance for a discussion of the significance of this):

Since the Hubble "constant" is a constant only in space, not in time, the radius of the Hubble sphere may increase or decrease over various time intervals. The subscript '0' indicates the value of the Hubble constant today.[12] Current evidence suggests that the expansion of the universe is accelerating (see Accelerating universe), meaning that for any given galaxy, the recession velocity dD/dt is increasing over time as the galaxy moves to greater and greater distances; however, the Hubble parameter is actually thought to be decreasing with time, meaning that if we were to look at some fixed distance D and watch a series of different galaxies pass that distance, later galaxies would pass that distance at a smaller velocity than earlier ones.[13]

سرعة الانزياح الأحمر والسرعة المتراجعة

سرعة الانزياح الأحمر



السرعة المتراجعة



We now define the Hubble constant as

واكتشاف قانون هبل:



or


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

القدرة على رصد المتغيرات

السرعة الزائدة مقابل السرعة النسبية

قانون هبل المثالي

المصير النهائي وعمر الكون

The age and ultimate fate of the universe can be determined by measuring the Hubble constant today and extrapolating with the observed value of the deceleration parameter, uniquely characterized by values of density parameters (ΩM for matter and ΩΛ for dark energy). A "closed universe" with ΩM > 1 and ΩΛ = 0 comes to an end in a Big Crunch and is considerably younger than its Hubble age. An "open universe" with ΩM ≤ 1 and ΩΛ = 0 expands forever and has an age that is closer to its Hubble age. For the accelerating universe with nonzero ΩΛ that we inhabit, the age of the universe is coincidentally very close to the Hubble age.

The value of the Hubble parameter changes over time, either increasing or decreasing depending on the value of the so-called deceleration parameter , which is defined by

In a universe with a deceleration parameter equal to zero, it follows that H = 1/t, where t is the time since the Big Bang. A non-zero, time-dependent value of simply requires integration of the Friedmann equations backwards from the present time to the time when the comoving horizon size was zero.

It was long thought that q was positive, indicating that the expansion is slowing down due to gravitational attraction. This would imply an age of the universe less than 1/H (which is about 14 billion years). For instance, a value for q of 1/2 (once favoured by most theorists) would give the age of the universe as 2/(3H). The discovery in 1998 that q is apparently negative means that the universe could actually be older than 1/H. However, estimates of the age of the universe are very close to 1/H.

مفارقة أولبرز

The expansion of space summarized by the Big Bang interpretation of Hubble's law is relevant to the old conundrum known as Olbers' paradox: If the universe were infinite in size, static, and filled with a uniform distribution of stars, then every line of sight in the sky would end on a star, and the sky would be as bright as the surface of a star. However, the night sky is largely dark.[14][15]

Since the 17th century, astronomers and other thinkers have proposed many possible ways to resolve this paradox, but the currently accepted resolution depends in part on the Big Bang theory, and in part on the Hubble expansion: In a universe that exists for a finite amount of time, only the light of a finite number of stars has had enough time to reach us, and the paradox is resolved. Additionally, in an expanding universe, distant objects recede from us, which causes the light emanated from them to be redshifted and diminished in brightness by the time we see it.[14][15]

ثابت هبل عديم الأبعاد

Instead of working with Hubble's constant, a common practice is to introduce the dimensionless Hubble constant, usually denoted by h, and to write Hubble's constant H0 as h × 100 km s−1 Mpc−1, all the relative uncertainty of the true value of H0 being then relegated to h.[16] The dimensionless Hubble constant is often used when giving distances that are calculated from redshift z using the formula dc/H0 × z. Since H0 is not precisely known, the distance is expressed as:

In other words, one calculates 2998×z and one gives the units as or

Occasionally a reference value other than 100 may be chosen, in which case a subscript is presented after h to avoid confusion; e.g. h70 denotes km s−1 Mpc−1, which implies .

This should not be confused with the dimensionless value of Hubble's constant, usually expressed in terms of Planck units, obtained by multiplying H0 by 1.75 × 10−63 (from definitions of parsec and tP), for example for H0=70, a Planck unit version of 1.2 × 10−61 is obtained.

تحديد ثابت هبل

Value of the Hubble Constant including measurement uncertainty above measurement method

تقدر أحدث القياسات (مارس 2010) ثابت هابل التي حصل عليها تلسكوب هابل الفضائي بواسطة مسبار ويلكينسون لقياس اختلاف الموجات الراديوية (تقدير ديسمبر 2012 (http://arxiv.org/pdf/1212.5225.pdf) ) بـ 3و69 (km/s)/(Mpc ), أي نحو 3و69 كيلومتر في الثانية لكل مليون فرسخ فلكي. (الفرسخ الفلكي = 3,26 سنة ضوئية).

إلا أنه توجد أيضا بعض القياسات الأخرى:

يهتم العلماء منذ سنين طويلة بالحصول على ثابت هابل بدقة. وهم لذلك يستخدمون أجهزة مختلفة لقياسه، منها تلسكوب هابل الفضائي، ومسبار ويلكينسون لقياس اختلاف الموجات الراديوية WMAP وأيضا قياسات تلسكوب شاندرا الفضائي للأشعة السينية.

يستغل تلسكوب هابل قياس ضوء المتغيرات القيفاوية (هي نجوم نباضة وتتميز بتناسب بين دورة ضوئها (الدورية) وقدر سطوعها)، كما تستغل المستعرات العظمى من نوع a1 كي تشكل "شمعات عيارية".

كما توجد طريقة جديدة لرصد المجرات وهي ظاهرة عدسة الجاذبية، وهي طريقة تمكن من قياس تغيرات سطوع المجرات عند عبرور ضوئها أحد عدسات الجاذبية. فعند عبور ضوء مجرة تقع خلف مجرة بالنسبة للمشاهد فإن مسارات ضوء المجرة الخلفية تتأثر بمجال الجاذبية للمجرة الوسطية بحيث تظهر للمشاهد كما لو كانت عدة مجرات وليست مجرة واحدة. فعند تغير سطوع المجرة المصدرة للضوء فإن هذا يغير أيضا من الصور التي يحصل عليها المشاهد. ومن معرفة هذا التغير في درجة السطوع يمكن حساب المافة بيننا وبين المجرة المصدرة للضوء. وبمعرفة بعدها وكذلك مقدار الانزياح الأحمر والذي يعطي سرعة اتعاد المجرة عنا يمكن تعيين معدل تمدد الكون.

أما الطريقة الثالثة وهي قياسات مسبار ويلكينسون لقياس اختلاف الموجات الراديوية فهي تختص بقياس توزيع الحرارة للموجات الكهرومغناطيسية في نطاق الميكروويف. ويمثل إشعاع الخلفية الميكروني الكوني جزءا تلك الأشعة الكهرومغناطيسية، وما إشعاع الخلفية هذا إلا بواقي التوزيع الحراري بعد الانفجار العظيم مباشرة. فمسبار ويلكينسون يقيس ذلك الاختلاف الضعيف في درجة الحرارة في صفحة السماء، وهي تمثل تشتت الإشعاع الأولي بوساطة المجرات وقت نشأتها وعطينا في وقتنا الحالي صورة لما كان في الماضي.

  • ومن نتائج قياسات أجراها مسبار ويلكينسون لمدة 5 سنوات نصل إلى القيمة:[18]:
  • ومن تحليل صور تلسكوب هابل التي أجراها باستخدام طريقة عدسات الجاذبية فهي تعطي قيمة لثابت هابل تبلغ:

[19]:

حيث : Mpc تساوي مليون parsec أي لكل مليون فرسخ فلكي. (مع العلم بأن الفرسخ الفلكي يعادل مسافة 3.3 سنة ضوئية)


القياسات السابقة ومناهج النقاش

تسارع الاتساع


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

اشتقاقات من متغير هبل


الكون المهمين عليه المادة (والثابت الكوني)


so Also, by definition,

and


الكون المهمين عليه المادة والطاقة المظلمة


لوكان كان الثابت w،


If dark energy does not have a constant equation-of-state w, then

and to solve this we must parametrize , for example if , giving


وحدات مشتقة من ثابت هبل

زمن هبل

طول هبل

حجم هبل


قيم مرصودة لثابت هبل

Multiple methods have been used to determine the Hubble constant. "Late universe" measurements using calibrated distance ladder techniques have converged on a value of approximately 73 km/s/Mpc. Since 2000, "early universe" techniques based on measurements of the cosmic microwave background have become available, and these agree on a value near 67.7 km/s/Mpc. (This is accounting for the change in the expansion rate since the early universe, so is comparable to the first number.) As techniques have improved, the estimated measurement uncertainties have shrunk, but the range of measured values has not, to the point that the disagreement is now statistically significant. This discrepancy is called the Hubble tension.[20][21]

اعتبارا من 2020, the cause of the discrepancy is not understood. In April 2019, astronomers reported further substantial discrepancies across different measurement methods in Hubble constant values, possibly suggesting the existence of a new realm of physics not currently well understood.[22][23][24][25][26] By November 2019, this tension had grown so far that some physicists like Joseph Silk had come to refer to it as a "possible crisis for cosmology", as the observed properties of the universe appear to be mutually inconsistent.[27] In February 2020, the Megamaser Cosmology Project published independent results that confirmed the distance ladder results and differed from the early-universe results at a statistical significance level of 95%.[28] In July 2020, measurements of the cosmic background radiation by the Atacama Cosmology Telescope predict that the Universe should be expanding more slowly than is currently observed.[29]

Estimated values of the Hubble constant, 2001–2020. Estimates in black represent calibrated distance ladder measurements which tend to cluster around 73 km/s/Mpc; red represents early universe CMB/BAO measurements with ΛCDM parameters which show good agreement on a figure near 67 km/s/Mpc, while blue are other techniques, whose uncertainties are not yet small enough to decide between the two.
تاريخ النشر ثابت هبل
(كم/ث)/Mpc
الراصد المصدر تعليقات / منهاج
2020-12-16 72.1±2.0 Hubble Space Telescope and Gaia EDR3 [30] Combining earlier work on red giant stars, using the tip of the red-giant branch (TRGB) distance indicator, with parallax measurements of Omega Centauri from Gaia EDR3.
2020-12-15 73.2±1.3 Hubble Space Telescope and Gaia EDR3 [31] Combination of HST photometry and Gaia EDR3 parallaxes for Milky Way Cepheids, reducing the uncertainty in calibration of Cepheid luminosities to 1.0%. Overall uncertainty in the value for is 1.8%, which is expected to be reduced to 1.3% with a larger sample of type Ia supernovae in galaxies that are known Cepheid hosts. Continuation of a collaboration known as Supernovae, , for the Equation of State of Dark Energy (SHoES).
2020-12-04 73.5±5.3 E. J. Baxter, B. D. Sherwin [32] Gravitational lensing in the CMB is used to estimate without referring to the sound horizon scale, providing an alternative method to analyze the Planck data.
2020-11-25 71.8+3.9
−3.3
P. Denzel et al. [33] Eight quadruply lensed galaxy systems are used to determine to a precision of 5%, in agreement with both "early" and "late" universe estimates. Independent of distance ladders and the cosmic microwave background.
2020-09-29 67.6+4.3
−4.2
S. Mukherjee et al. [34] Gravitational waves, assuming that the transient ZTF19abanrh found by the Zwicky Transient Facility is the optical counterpart to GW190521. Independent of distance ladders and the cosmic microwave background.
2020-02-26 73.9±3.0 Megamaser Cosmology Project [28] Geometric distance measurements to megamaser-hosting galaxies. Independent of distance ladders and the cosmic microwave background.
2019-10-14 74.2+2.7
−3.0
STRIDES [35] Modelling the mass distribution & time delay of the lensed quasar DES J0408-5354.
2019-09-12 76.8±2.6 SHARP/H0LiCOW [36] Modelling three galactically lensed objects and their lenses using ground-based adaptive optics and the Hubble Space Telescope.
2019-08-20 70.3+1.36
−1.35
K. Dutta et al. [37] This is obtained analysing low-redshift cosmological data within ΛCDM model. The datasets used are type-Ia supernovae, baryon acoustic oscillations, time-delay measurements using strong-lensing, measurements using cosmic chronometers and growth measurements from large scale structure observations.
2019-08-15 73.5±1.4 M. J. Reid, D. W. Pesce, A. G. Riess [38] Measuring the distance to Messier 106 using its supermassive black hole, combined with measurements of eclipsing binaries in the Large Magellanic Cloud.
2019-07-16 69.8±1.9 Hubble Space Telescope [39][40][41] Distances to red giant stars are calculated using the tip of the red-giant branch (TRGB) distance indicator.
2019-07-10 73.3+1.7
−1.8
H0LiCOW collaboration [42] Updated observations of multiply imaged quasars, now using six quasars, independent of the cosmic distance ladder and independent of the cosmic microwave background measurements.
2019-07-08 70.3+5.3
−5.0
LIGO and Virgo detectors [43] Uses radio counterpart of GW170817, combined with earlier gravitational wave (GW) and electromagnetic (EM) data.
2019-03-28 68.0+4.2
−4.1
Fermi-LAT [44] Gamma ray attenuation due to extragalactic light. Independent of the cosmic distance ladder and the cosmic microwave background.
2019-03-18 74.03±1.42 Hubble Space Telescope [22] Precision HST photometry of Cepheids in the Large Magellanic Cloud (LMC) reduce the uncertainty in the distance to the LMC from 2.5% to 1.3%. The revision increases the tension with CMB measurements to the 4.4σ level (P=99.999% for Gaussian errors), raising the discrepancy beyond a plausible level of chance. Continuation of a collaboration known as Supernovae, , for the Equation of State of Dark Energy (SHoES).
2019-02-08 67.78+0.91
−0.87
Joseph Ryan et al. [45] Quasar angular size and baryon acoustic oscillations, assuming a flat LambdaCDM model. Alternative models result in different (generally lower) values for the Hubble constant.
2018-11-06 67.77±1.30 Dark Energy Survey [46] Supernova measurements using the inverse distance ladder method based on baryon acoustic oscillations.
2018-09-05 72.5+2.1
−2.3
H0LiCOW collaboration [47] Observations of multiply imaged quasars, independent of the cosmic distance ladder and independent of the cosmic microwave background measurements.
2018-07-18 67.66±0.42 Planck Mission [48] Final Planck 2018 results.
2018-04-27 73.52±1.62 Hubble Space Telescope and Gaia [49][50] Additional HST photometry of galactic Cepheids with early Gaia parallax measurements. The revised value increases tension with CMB measurements at the 3.8σ level. Continuation of the SHoES collaboration.
2018-02-22 73.45±1.66 Hubble Space Telescope [51][52] Parallax measurements of galactic Cepheids for enhanced calibration of the distance ladder; the value suggests a discrepancy with CMB measurements at the 3.7σ level. The uncertainty is expected to be reduced to below 1% with the final release of the Gaia catalog. SHoES collaboration.
2017-10-16 70.0+12.0
−8.0
The LIGO Scientific Collaboration and The Virgo Collaboration [53] Standard siren measurement independent of normal "standard candle" techniques; the gravitational wave analysis of a binary neutron star (BNS) merger GW170817 directly estimated the luminosity distance out to cosmological scales. An estimate of fifty similar detections in the next decade may arbitrate tension of other methodologies.[54] Detection and analysis of a neutron star-black hole merger (NSBH) may provide greater precision than BNS could allow.[55]
2016-11-22 71.9+2.4
−3.0
Hubble Space Telescope [56] Uses time delays between multiple images of distant variable sources produced by strong gravitational lensing. Collaboration known as Lenses in COSMOGRAIL's Wellspring (H0LiCOW).
2016-08-04 76.2+3.4
−2.7
Cosmicflows-3 [57] Comparing redshift to other distance methods, including Tully–Fisher, Cepheid variable, and Type Ia supernovae. A restrictive estimate from the data implies a more precise value of 75±2.
2016-07-13 67.6+0.7
−0.6
SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) [58] Baryon acoustic oscillations. An extended survey (eBOSS) began in 2014 and is expected to run through 2020. The extended survey is designed to explore the time when the universe was transitioning away from the deceleration effects of gravity from 3 to 8 billion years after the Big Bang.[59]
2016-05-17 73.24±1.74 Hubble Space Telescope [60] Type Ia supernova, the uncertainty is expected to go down by a factor of more than two with upcoming Gaia measurements and other improvements. SHoES collaboration.
2015-02 67.74±0.46 Planck Mission [61][62] Results from an analysis of Planck's full mission were made public on 1 December 2014 at a conference in Ferrara, Italy. A full set of papers detailing the mission results were released in February 2015.
2013-10-01 74.4±3.0 Cosmicflows-2 [63] Comparing redshift to other distance methods, including Tully–Fisher, Cepheid variable, and Type Ia supernovae.
2013-03-21 67.80±0.77 Planck Mission [64][65][66][67][68] The ESA Planck Surveyor was launched in May 2009. Over a four-year period, it performed a significantly more detailed investigation of cosmic microwave radiation than earlier investigations using HEMT radiometers and bolometer technology to measure the CMB at a smaller scale than WMAP. On 21 March 2013, the European-led research team behind the Planck cosmology probe released the mission's data including a new CMB all-sky map and their determination of the Hubble constant.
2012-12-20 69.32±0.80 WMAP (9 years), combined with other measurements. [69]
2010 70.4+1.3
−1.4
WMAP (7 years), combined with other measurements. [70] These values arise from fitting a combination of WMAP and other cosmological data to the simplest version of the ΛCDM model. If the data are fit with more general versions, H0 tends to be smaller and more uncertain: typically around 67±4 (km/s)/Mpc although some models allow values near 63 (km/s)/Mpc.[71]
2010 71.0±2.5 WMAP only (7 years). [70]
2009-02 70.5±1.3 WMAP (5 years), combined with other measurements. [72]
2009-02 71.9+2.6
−2.7
WMAP only (5 years) [72]
2007 70.4+1.5
−1.6
WMAP (3 years), combined with other measurements. [73]
2006-08 76.9+10.7
−8.7
Chandra X-ray Observatory [74] Combined Sunyaev–Zel'dovich effect and Chandra X-ray observations of galaxy clusters. Adjusted uncertainty in table from Planck Collaboration 2013.[75]
2001-05 72±8 Hubble Space Telescope Key Project [76] This project established the most precise optical determination, consistent with a measurement of H0 based upon Sunyaev–Zel'dovich effect observations of many galaxy clusters having a similar accuracy.
before 1996 50–90 (est.) [77]
early 1970s ≈ 55 (est.) Allan Sandage and Gustav Tammann [78]
1958 75 (est.) Allan Sandage [79] This was the first good estimate of H0, but it would be decades before a consensus was achieved.
1956 180 Humason, Mayall and Sandage [78]
1929 500 Edwin Hubble, Hooker telescope [80][78][81]
1927 625 Georges Lemaître [82] First measurement and interpretation as a sign of the expansion of the universe

انظر أيضاً


الهوامش

  1. ^ Peter Coles, ed. (2001). Routledge Critical Dictionary of the New Cosmology. Routledge. p. 202. ISBN 0203164571.
  2. ^ Lemaître, Georges (1927). "Un univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques". Annales de la Société Scientifique de Bruxelles. A47: 49–56. {{cite journal}}: Invalid |ref=harv (help) translated by A. S. Eddington Lemaître, Georges (1931). "Expansion of the universe, A homogeneous universe of constant mass and increasing radius accounting for the radial velocity of extra-galactic nebulæ". Monthly Notices of the Royal Astronomical Society. 91: 483–490. {{cite journal}}: Invalid |ref=harv (help)
  3. ^ Hubble, Edwin, "A Relation between Distance and Radial Velocity among Extra-Galactic Nebulae" (1929) Proceedings of the National Academy of Sciences of the United States of America, Volume 15, Issue 3, pp. 168-173 (Full article, PDF)
  4. ^ Malcolm S Longair (2006). The Cosmic Century. Cambridge University Press. p. 109. ISBN 0521474361.
  5. ^ "Three steps to the Hubble constant". www.spacetelescope.org. Retrieved 26 February 2018.
  6. ^ Wendy L Freedman; et al. (2001). "Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant". Astrophys J. 553 (1): 47–72. arXiv:astro-ph/0012376. Bibcode:2001ApJ...553...47F. doi:10.1086/320638. {{cite journal}}: Invalid |ref=harv (help); Unknown parameter |author-separator= ignored (help)
  7. ^ Steven Weinberg (2008). Cosmology. Oxford University Press. p. 28. ISBN 0-19-852682-2.
  8. ^ أ ب "What is a Cosmological Constant?". Goddard Space Flight Center. Retrieved 2013-10-17.
  9. ^ Isaacson, W. (2007). Einstein: His Life and Universe. Simon & Schuster. p. 354. ISBN 978-0-7432-6473-0.
  10. ^ "Einstein's Biggest Blunder? Dark Energy May Be Consistent With Cosmological Constant". Science Daily. 28 November 2007. Retrieved 2013-06-02.
  11. ^ قالب:Cite arxiv
  12. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة Keel
  13. ^ "Is the universe expanding faster than the speed of light?". Ask an Astronomer at Cornell University. Archived from the original on 23 November 2003. Retrieved 5 June 2015.
  14. ^ أ ب Chase, S. I.; Baez, J. C. (2004). "Olbers' Paradox". The Original Usenet Physics FAQ. Retrieved 2013-10-17.
  15. ^ أ ب Asimov, I. (1974). "The Black of Night". Asimov on Astronomy. Doubleday. ISBN 978-0-385-04111-9.
  16. ^ Peebles, P. J. E. (1993). Principles of Physical Cosmology. Princeton University Press.
  17. ^ Hubble-Konstante Mai 2009 (Hubble)
  18. ^ Hubble-Konstante Oktober 2008 (WMAP5)، arXiv.org: WMAP5 (v2)
  19. ^ Hubble-Konstante März 2010 (Gravitationslinsen)
  20. ^ Poulin, Vivian; Smith, Tristan L.; Karwal, Tanvi; Kamionkowski, Marc (2019-06-04). "Early Dark Energy can Resolve the Hubble Tension". Physical Review Letters. 122 (22): 221301. arXiv:1811.04083. Bibcode:2019PhRvL.122v1301P. doi:10.1103/PhysRevLett.122.221301. PMID 31283280. S2CID 119233243.
  21. ^ Mann, Adam (26 August 2019). "One Number Shows Something Is Fundamentally Wrong with Our Conception of the Universe - This fight has universal implications". Live Science. Retrieved 26 August 2019.
  22. ^ أ ب Riess, Adam G.; Casertano, Stefano; Yuan, Wenlong; Macri, Lucas M.; Scolnic, Dan (18 March 2019). "Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM". The Astrophysical Journal. 876 (1): 85. arXiv:1903.07603. Bibcode:2019ApJ...876...85R. doi:10.3847/1538-4357/ab1422. S2CID 85528549.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  23. ^ NASA/Goddard Space Flight Center (25 April 2019). "Mystery of the universe's expansion rate widens with new Hubble data". EurekAlert!. Retrieved 27 April 2019.
  24. ^ Wall, Mike (25 April 2019). "The Universe Is Expanding So Fast We Might Need New Physics to Explain It". Space.com. Retrieved 27 April 2019.
  25. ^ Mandelbaum, Ryan F. (25 April 2019). "Hubble Measurements Confirm There's Something Weird About How the Universe Is Expanding". Gizmodo. Retrieved 26 April 2019.
  26. ^ Pietrzyński, G; et al. (13 March 2019). "A distance to the Large Magellanic Cloud that is precise to one per cent". Nature. 567 (7747): 200–203. arXiv:1903.08096. Bibcode:2019Natur.567..200P. doi:10.1038/s41586-019-0999-4. PMID 30867610. S2CID 76660316.
  27. ^ Di Valentino, E.; Melchiorri, A.; Silk, J. (4 November 2019). "Planck evidence for a closed Universe and a possible crisis for cosmology". Nature Astronomy. 4 (2019): 196–203. arXiv:1911.02087. Bibcode:2019NatAs.tmp..484D. doi:10.1038/s41550-019-0906-9. S2CID 207880880.{{cite journal}}: CS1 maint: bibcode (link)
  28. ^ أ ب Pesce, D. W.; Braatz, J. A.; Reid, M. J.; Riess, A. G.; et al. (26 February 2020). "The Megamaser Cosmology Project. XIII. Combined Hubble Constant Constraints". The Astrophysical Journal. 891 (1): L1. arXiv:2001.09213. Bibcode:2020ApJ...891L...1P. doi:10.3847/2041-8213/ab75f0. S2CID 210920444.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  29. ^ Castelvecchi, Davide (2020-07-15). "Mystery over Universe's expansion deepens with fresh data". Nature (in الإنجليزية). 583 (7817): 500–501. Bibcode:2020Natur.583..500C. doi:10.1038/d41586-020-02126-6. PMID 32669728. S2CID 220583383.
  30. ^ Soltis, J.; Casertano, S.; Riess, A. G. (16 December 2020). "The Parallax of Omega Centauri Measured from Gaia EDR3 and a Direct, Geometric Calibration of the Tip of the Red Giant Branch and the Hubble Constant". arXiv:2012.09196. {{cite journal}}: Cite journal requires |journal= (help)
  31. ^ Riess, A. G.; Casertano, S.; Yuan, W.; Bowers, J. B.; et al. (15 December 2020). "Cosmic Distances Calibrated to 1% Precision with Gaia EDR3 Parallaxes and Hubble Space Telescope Photometry of 75 Milky Way Cepheids Confirm Tension with LambdaCDM". arXiv:2012.08534. {{cite journal}}: Cite journal requires |journal= (help)
  32. ^ Baxter, E. J.; Sherwin, B. D. (February 2021). "Determining the Hubble constant without the sound horizon scale: measurements from CMB lensing". Monthly Notices of the Royal Astronomical Society. 501 (2): 1823–1835. arXiv:2007.04007. doi:10.1093/mnras/staa3706.
  33. ^ Denzel, P.; Coles, J. P.; Saha, P.; Williams, L. L. R. (February 2021). "The Hubble constant from eight time-delay galaxy lenses". Monthly Notices of the Royal Astronomical Society. 501 (1): 784–801. arXiv:2007.14398. doi:10.1093/mnras/staa3603.
  34. ^ Mukherjee, S.; Ghosh, A.; Graham, M. J.; Karathanasis, C.; et al. (29 September 2020). "First measurement of the Hubble parameter from bright binary black hole GW190521". arXiv:2009.14199. {{cite journal}}: Cite journal requires |journal= (help)
  35. ^ Shajib, A. J.; Birrer, S.; Treu, T.; Agnello, A.; Buckley-Geer, E. J.; Chan, J. H. H.; Christensen, L.; Lemon, C.; et al. (14 October 2019). STRIDES: A 3.9 per cent measurement of the Hubble constant from the strongly lensed system DES J0408-5354. doi:10.1093/mnras/staa828. 
  36. ^ Chen, G.C.-F.; Fassnacht, C.D.; Suyu, S.H.; Rusu, C.E.; et al. (12 September 2019). "A SHARP view of H0LiCOW: H0 from three time-delay gravitational lens systems with adaptive optics imaging". Monthly Notices of the Royal Astronomical Society (in الإنجليزية). 490 (2): 1743–1773. arXiv:1907.02533. Bibcode:2019MNRAS.490.1743C. doi:10.1093/mnras/stz2547. S2CID 195820422.
  37. ^ Dutta, Koushik; Roy, Anirban; Ruchika, Ruchika; Sen, Anjan A.; Sheikh-Jabbari, M. M. (20 August 2019). "Cosmology With Low-Redshift Observations: No Signal For New Physics". Phys. Rev. D (in الإنجليزية). 100 (10): 103501. arXiv:1908.07267. Bibcode:2019PhRvD.100j3501D. doi:10.1103/PhysRevD.100.103501. S2CID 201107151.
  38. ^ Reid, M. J.; Pesce, D. W.; Riess, A. G. (15 August 2019). "An Improved Distance to NGC 4258 and its Implications for the Hubble Constant". The Astrophysical Journal (in الإنجليزية). 886 (2): L27. arXiv:1908.05625. Bibcode:2019ApJ...886L..27R. doi:10.3847/2041-8213/ab552d. S2CID 199668809.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  39. ^ Carnegie Institution of Science (16 July 2019). "New measurement of universe's expansion rate is 'stuck in the middle' - Red giant stars observed by Hubble Space Telescope used to make an entirely new measurement of how fast the universe is expanding". EurekAlert!. Retrieved 16 July 2019.
  40. ^ Sokol, Joshua (19 July 2019). "Debate intensifies over speed of expanding universe". Science. doi:10.1126/science.aay8123. Retrieved 20 July 2019.
  41. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة The Carnegie-Chicago Hubble Program
  42. ^ Kenneth C. Wong (2020). "H0LiCOW XIII. A 2.4% measurement of H0 from lensed quasars: 5.3σ tension between early and late-Universe probes". Monthly Notices of the Royal Astronomical Society. arXiv:1907.04869. doi:10.1093/mnras/stz3094. S2CID 195886279.
  43. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة NAT-20190708
  44. ^ Domínguez, Alberto; et al. (28 March 2019). "A new measurement of the Hubble constant and matter content of the Universe using extragalactic background light γ-ray attenuation". The Astrophysical Journal. 885 (2): 137. arXiv:1903.12097v1. Bibcode:2019ApJ...885..137D. doi:10.3847/1538-4357/ab4a0e. S2CID 85543845.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  45. ^ Ryan, Joseph; Chen, Yun; Ratra, Bharat (8 February 2019), "Baryon acoustic oscillation, Hubble parameter, and angular size measurement constraints on the Hubble constant, dark energy dynamics, and spatial curvature", Monthly Notices of the Royal Astronomical Society 488 (3): 3844–3856, doi:10.1093/mnras/stz1966, Bibcode2019MNRAS.tmp.1893R 
  46. ^ Macaulay, E; et al. (DES collaboration) (2018). "First Cosmological Results using Type Ia Supernovae from the Dark Energy Survey: Measurement of the Hubble Constant". Monthly Notices of the Royal Astronomical Society. 486 (2): 2184–2196. arXiv:1811.02376. doi:10.1093/mnras/stz978. S2CID 119310644.
  47. ^ Birrer, S; Treu, T; Rusu, C. E; Bonvin, V; et al. (2018). "H0LiCOW - IX. Cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 and a new measurement of the Hubble constant". Monthly Notices of the Royal Astronomical Society. 484 (4): 4726–4753. arXiv:1809.01274. Bibcode:2018arXiv180901274B. doi:10.1093/mnras/stz200. S2CID 119053798.
  48. ^ Planck Collaboration; Aghanim, N.; et al. (2018). "Planck 2018 results. VI. Cosmological parameters". arXiv:1807.06209. Bibcode:2018arXiv180706209P.
  49. ^ Riess, Adam G.; Casertano, Stefano; Yuan, Wenlong; Macri, Lucas; et al. (2018). "Milky Way Cepheid Standards for Measuring Cosmic Distances and Application to Gaia DR2: Implications for the Hubble Constant". The Astrophysical Journal (in الإنجليزية). 861 (2): 126. arXiv:1804.10655. Bibcode:2018ApJ...861..126R. doi:10.3847/1538-4357/aac82e. ISSN 0004-637X. S2CID 55643027.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  50. ^ Devlin, Hannah (10 May 2018). "The answer to life, the universe and everything might be 73. Or 67". the Guardian (in الإنجليزية). Retrieved 13 May 2018.
  51. ^ Riess, Adam G.; Casertano, Stefano; Yuan, Wenlong; Macri, Lucas; et al. (22 February 2018). "New parallaxes of galactic Cepheids from spatially scanning the Hubble Space Telescope: Implications for the Hubble constant" (PDF). The Astrophysical Journal. 855 (2): 136. arXiv:1801.01120. Bibcode:2018ApJ...855..136R. doi:10.3847/1538-4357/aaadb7. S2CID 67808349. Retrieved 23 February 2018.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  52. ^ Weaver, Donna; Villard, Ray; Hille, Karl (22 February 2018). "Improved Hubble Yardstick Gives Fresh Evidence for New Physics in the Universe". NASA. Retrieved 24 February 2018.
  53. ^ The LIGO Scientific Collaboration and The Virgo Collaboration; The 1M2H Collaboration; The Dark Energy Camera GW-EM Collaboration and the DES Collaboration; The DLT40 Collaboration; et al. (2017-10-16). "A gravitational-wave standard siren measurement of the Hubble constant" (PDF). Nature (in الإنجليزية). 551 (7678): 85–88. arXiv:1710.05835. Bibcode:2017Natur.551...85A. doi:10.1038/nature24471. ISSN 1476-4687. PMID 29094696. S2CID 205261622.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  54. ^ Feeney, Stephen M; Peiris, Hiranya V; Williamson, Andrew R; Nissanke, Samaya M; et al. (2019). "Prospects for resolving the Hubble constant tension with standard sirens". Physical Review Letters. 122 (6): 061105. arXiv:1802.03404. Bibcode:2019PhRvL.122f1105F. doi:10.1103/PhysRevLett.122.061105. hdl:2066/201510. PMID 30822066. S2CID 73493934.
  55. ^ Vitale, Salvatore; Chen, Hsin-Yu (12 July 2018). "Measuring the Hubble Constant with Neutron Star Black Hole Mergers". Physical Review Letters. 121 (2): 021303. arXiv:1804.07337. Bibcode:2018PhRvL.121b1303V. doi:10.1103/PhysRevLett.121.021303. hdl:1721.1/117110. PMID 30085719. S2CID 51940146.
  56. ^ Bonvin, Vivien; Courbin, Frédéric; Suyu, Sherry H.; et al. (2016-11-22). "H0LiCOW – V. New COSMOGRAIL time delays of HE 0435−1223: H0 to 3.8 per cent precision from strong lensing in a flat ΛCDM model". MNRAS. 465 (4): 4914–4930. arXiv:1607.01790. Bibcode:2017MNRAS.465.4914B. doi:10.1093/mnras/stw3006. S2CID 109934944.
  57. ^ Tully, R. Brent; Courtois, Hélène M.; Sorce, Jenny G. (3 August 2016). "COSMICFLOWS-3". The Astronomical Journal. 152 (2): 50. arXiv:1605.01765. Bibcode:2016AJ....152...50T. doi:10.3847/0004-6256/152/2/50.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  58. ^ Grieb, Jan N.; Sánchez, Ariel G.; Salazar-Albornoz, Salvador (2016-07-13). "The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sample". Monthly Notices of the Royal Astronomical Society. 467 (2): stw3384. arXiv:1607.03143. Bibcode:2017MNRAS.467.2085G. doi:10.1093/mnras/stw3384. S2CID 55888085.
  59. ^ "The Extended Baryon Oscillation Spectroscopic Survey (eBOSS)". SDSS. Retrieved 13 May 2018.
  60. ^ Riess, Adam G.; Macri, Lucas M.; Hoffmann, Samantha L.; Scolnic, Dan; et al. (2016-04-05). "A 2.4% Determination of the Local Value of the Hubble Constant". The Astrophysical Journal. 826 (1): 56. arXiv:1604.01424. Bibcode:2016ApJ...826...56R. doi:10.3847/0004-637X/826/1/56. S2CID 118630031.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  61. ^ "Planck Publications: Planck 2015 Results". European Space Agency. February 2015. Retrieved 9 February 2015.
  62. ^ Cowen, Ron; Castelvecchi, Davide (2 December 2014). "European probe shoots down dark-matter claims". Nature. doi:10.1038/nature.2014.16462. Retrieved 6 December 2014.
  63. ^ Tully, R. Brent; Courtois, Helene M.; Dolphin, Andrew E.; Fisher, J. Richard; et al. (5 September 2013). "Cosmicflows-2: The Data". The Astronomical Journal. 146 (4): 86. arXiv:1307.7213. Bibcode:2013AJ....146...86T. doi:10.1088/0004-6256/146/4/86. ISSN 0004-6256. S2CID 118494842.
  64. ^ Bucher, P. A. R.; et al. (Planck Collaboration) (2013). "Planck 2013 results. I. Overview of products and scientific Results". Astronomy & Astrophysics. 571: A1. arXiv:1303.5062. Bibcode:2014A&A...571A...1P. doi:10.1051/0004-6361/201321529. S2CID 218716838.
  65. ^ "Planck reveals an almost perfect universe". ESA. 21 March 2013. Retrieved 2013-03-21.
  66. ^ "Planck Mission Brings Universe Into Sharp Focus". JPL. 21 March 2013. Retrieved 2013-03-21.
  67. ^ Overbye, D. (21 March 2013). "An infant universe, born before we knew". New York Times. Retrieved 2013-03-21.
  68. ^ Boyle, A. (21 March 2013). "Planck probe's cosmic 'baby picture' revises universe's vital statistics". NBC News. Retrieved 2013-03-21.
  69. ^ Bennett, C. L.; et al. (2013). "Nine-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: Final maps and results". The Astrophysical Journal Supplement Series. 208 (2): 20. arXiv:1212.5225. Bibcode:2013ApJS..208...20B. doi:10.1088/0067-0049/208/2/20. S2CID 119271232.
  70. ^ أ ب Jarosik, N.; et al. (2011). "Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: Sky maps, systematic errors, and basic results". The Astrophysical Journal Supplement Series. 192 (2): 14. arXiv:1001.4744. Bibcode:2011ApJS..192...14J. doi:10.1088/0067-0049/192/2/14. S2CID 46171526.
  71. ^ Results for H0 and other cosmological parameters obtained by fitting a variety of models to several combinations of WMAP and other data are available at the NASA's LAMBDA website Archived 2014-07-09 at the Wayback Machine.
  72. ^ أ ب Hinshaw, G.; et al. (WMAP Collaboration) (2009). "Five-year Wilkinson Microwave Anisotropy Probe observations: Data processing, sky maps, and basic results". The Astrophysical Journal Supplement. 180 (2): 225–245. arXiv:0803.0732. Bibcode:2009ApJS..180..225H. doi:10.1088/0067-0049/180/2/225. S2CID 3629998.
  73. ^ Spergel, D. N.; et al. (WMAP Collaboration) (2007). "Three-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Implications for cosmology". The Astrophysical Journal Supplement Series. 170 (2): 377–408. arXiv:astro-ph/0603449. Bibcode:2007ApJS..170..377S. doi:10.1086/513700. S2CID 1386346.
  74. ^ Bonamente, M.; Joy, M. K.; Laroque, S. J.; Carlstrom, J. E.; et al. (2006). "Determination of the cosmic distance scale from Sunyaev–Zel'dovich effect and Chandra X‐ray measurements of high‐redshift galaxy clusters". The Astrophysical Journal. 647 (1): 25. arXiv:astro-ph/0512349. Bibcode:2006ApJ...647...25B. doi:10.1086/505291. S2CID 15723115.
  75. ^ Planck Collaboration (2013). "Planck 2013 results. XVI. Cosmological parameters". Astronomy & Astrophysics. 571: A16. arXiv:1303.5076. Bibcode:2014A&A...571A..16P. doi:10.1051/0004-6361/201321591. S2CID 118349591.
  76. ^ Freedman, W. L.; et al. (2001). "Final results from the Hubble Space Telescope Key Project to measure the Hubble constant". The Astrophysical Journal. 553 (1): 47–72. arXiv:astro-ph/0012376. Bibcode:2001ApJ...553...47F. doi:10.1086/320638. S2CID 119097691.
  77. ^ Overbye, D. (1999). "Prologue". Lonely Hearts of the Cosmos (2nd ed.). HarperCollins. p. 1ff. ISBN 978-0-316-64896-7.
  78. ^ أ ب ت John P. Huchra (2008). "The Hubble Constant". Harvard Center for Astrophysics.
  79. ^ Sandage, A. R. (1958). "Current problems in the extragalactic distance scale". The Astrophysical Journal. 127 (3): 513–526. Bibcode:1958ApJ...127..513S. doi:10.1086/146483.
  80. ^ Edwin Hubble, A Relation between Distance and Radial Velocity among Extra-Galactic Nebulae, Proceedings of the National Academy of Sciences, vol. 15, no. 3, pp. 168-173, March 1929
  81. ^ "Hubble's Constant". Skywise Unlimited - Western Washington University.
  82. ^ Lemaître, Georges (1927). "Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques". Annales de la Société Scientifique de Bruxelles (in الفرنسية). A47: 49–59. Bibcode:1927ASSB...47...49L.

المصادر

  • Eng, A. E. (1985). "A New Approach to Starlight Runs". Oswego. {{cite journal}}: Cite journal requires |journal= (help); Invalid |ref=harv (help)
  • Hubble, E. P. (1937). The Observational Approach to Cosmology. Oxford: Clarendon Press 
  • Kutner, Marc (2003). Astronomy: A Physical Perspective. New York: Cambridge University Press. ISBN 0-521-52927-1. {{cite book}}: Invalid |ref=harv (help)
  • Liddle, Andrew R. (2003). An Introduction to Modern Cosmology (2nd ed.). Chichester: Wiley. ISBN 0-470-84835-9. {{cite book}}: Invalid |ref=harv (help)

قراءات إضافية

وصلات خارجية