Ultimate fate of the universe

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The ultimate fate of the universe is a topic in physical cosmology, whose theoretical restrictions allow possible scenarios for the evolution and ultimate fate of the universe to be described and evaluated. Based on available observational evidence, deciding the fate and evolution of the universe has become a valid cosmological question, being beyond the mostly untestable constraints of mythological or theological beliefs. Several possible futures have been predicted by different scientific hypotheses, including that the universe might have existed for a finite and infinite duration, or towards explaining the manner and circumstances of its beginning.

Contents

Observations made by Edwin Hubble during the 1930s–1950s found that galaxies appeared to be moving away from each other, leading to the currently accepted Big Bang theory. This suggests that the universe began very dense about 13.787 billion years ago, and it has expanded and (on average) become less dense ever since. [1] Confirmation of the Big Bang mostly depends on knowing the rate of expansion, average density of matter, and the physical properties of the mass–energy in the universe.

There is a strong consensus among cosmologists that the shape of the universe is considered "flat" (parallel lines stay parallel) and will continue to expand forever. [2] [3]

Factors that need to be considered in determining the universe's origin and ultimate fate include the average motions of galaxies, the shape and structure of the universe, and the amount of dark matter and dark energy that the universe contains.

Emerging scientific basis

Theory

The theoretical scientific exploration of the ultimate fate of the universe became possible with Albert Einstein's 1915 theory of general relativity. General relativity can be employed to describe the universe on the largest possible scale. There are several possible solutions to the equations of general relativity, and each solution implies a possible ultimate fate of the universe.

Alexander Friedmann proposed several solutions in 1922, as did Georges Lemaître in 1927. [4] In some of these solutions, the universe has been expanding from an initial singularity which was, essentially, the Big Bang.

Observation

In 1929, Edwin Hubble published his conclusion, based on his observations of Cepheid variable stars in distant galaxies, that the universe was expanding. From then on, the beginning of the universe and its possible end have been the subjects of serious scientific investigation.

Big Bang and Steady State theories

In 1927, Georges Lemaître set out a theory that has since come to be called the Big Bang theory of the origin of the universe. [4] In 1948, Fred Hoyle set out his opposing Steady State theory in which the universe continually expanded but remained statistically unchanged as new matter is constantly created. These two theories were active contenders until the 1965 discovery, by Arno Allan Penzias and Robert Woodrow Wilson, of the cosmic microwave background radiation, a fact that is a straightforward prediction of the Big Bang theory, and one that the original Steady State theory could not account for. As a result, the Big Bang theory quickly became the most widely held view of the origin of the universe.

Cosmological constant

Einstein and his contemporaries believed in a static universe. When Einstein found that his general relativity equations could easily be solved in such a way as to allow the universe to be expanding at the present and contracting in the far future, he added to those equations what he called a cosmological constant ⁠— ⁠essentially a constant energy density, unaffected by any expansion or contraction ⁠— ⁠whose role was to offset the effect of gravity on the universe as a whole in such a way that the universe would remain static. However, after Hubble announced his conclusion that the universe was expanding, Einstein would write that his cosmological constant was "the greatest blunder of my life." [5]

Density parameter

An important parameter in fate of the universe theory is the density parameter, omega (), 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 is equal to, less than, or greater than . These are called, respectively, the flat, open and closed universes. These three adjectives refer to the overall geometry of the universe, and not to the local curving of spacetime caused by smaller clumps of mass (for example, galaxies and stars). If the primary content of the universe is inert matter, as in the dust models popular for much of the 20th century, there is a particular fate corresponding to each geometry. Hence cosmologists aimed to determine the fate of the universe by measuring , or equivalently the rate at which the expansion was decelerating.

Repulsive force

Starting in 1998, observations of supernovas in distant galaxies have been interpreted as consistent [6] with a universe whose expansion is accelerating. Subsequent cosmological theorizing has been designed so as to allow for this possible acceleration, nearly always by invoking dark energy, which in its simplest form is just a positive cosmological constant. In general, dark energy is a catch-all term for any hypothesized field with negative pressure, usually with a density that changes as the universe expands. Some cosmologists are studying whether dark energy which varies in time (due to a portion of it being caused by a scalar field in the early universe) can solve the crisis in cosmology. [7] Upcoming galaxy surveys from the Euclid, Nancy Grace Roman and James Webb space telescopes (and data from next-generation ground-based telescopes) are expected to further develop our understanding of dark energy (specifically whether it is best understood as a constant energy intrinsic to space, as a time varying quantum field or as something else entirely). [8]

Role of the shape of the universe

The ultimate fate of an expanding universe depends on the matter density O M {\displaystyle \Omega _{M}} and the dark energy density O L {\displaystyle \Omega _{\Lambda }} . Friedmann universes.svg
The ultimate fate of an expanding universe depends on the matter density and the dark energy density .

The current scientific consensus of most cosmologists is that the ultimate fate of the universe depends on its overall shape, how much dark energy it contains and on the equation of state which determines how the dark energy density responds to the expansion of the universe. [3] Recent observations conclude, from 7.5 billion years after the Big Bang, that the expansion rate of the universe has probably been increasing, commensurate with the Open Universe theory. [9] However, measurements made by the Wilkinson Microwave Anisotropy Probe suggest that the universe is either flat or very close to flat. [2]

Closed universe

If , the geometry of space is closed like the surface of a sphere. The sum of the angles of a triangle exceeds 180 degrees and there are no parallel lines; all lines eventually meet. The geometry of the universe is, at least on a very large scale, elliptic.

In a closed universe, gravity eventually stops the expansion of the universe, after which it starts to contract until all matter in the universe collapses to a point, a final singularity termed the "Big Crunch", the opposite of the Big Bang. If, however, the universe contains dark energy, then the resulting repulsive force may be sufficient to cause the expansion of the universe to continue forever—even if . [10] This is the case in the currently accepted Lambda-CDM model, where dark energy is found through observations to account for roughly 68% of the total energy content of the universe. According to the Lambda-CDM model, the universe would need to have an average matter density roughly seventeen times greater than its measured value today in order for the effects of dark energy to be overcome and the universe to eventually collapse. This is in spite of the fact that, according to the Lambda-CDM model, any increase in matter density would result in .

Open universe

If , the geometry of space is open, i.e., negatively curved like the surface of a saddle. The angles of a triangle sum to less than 180 degrees, and lines that do not meet are never equidistant; they have a point of least distance and otherwise grow apart. The geometry of such a universe is hyperbolic. [11]

Even without dark energy, a negatively curved universe expands forever, with gravity negligibly slowing the rate of expansion. With dark energy, the expansion not only continues but accelerates. The ultimate fate of an open universe with dark energy is either universal heat death or a "Big Rip" [12] [13] [14] [15] where the acceleration caused by dark energy eventually becomes so strong that it completely overwhelms the effects of the gravitational, electromagnetic and strong binding forces. Conversely, a negative cosmological constant, which would correspond to a negative energy density and positive pressure, would cause even an open universe to re-collapse to a big crunch.

Flat universe

If the average density of the universe exactly equals the critical density so that , then the geometry of the universe is flat: as in Euclidean geometry, the sum of the angles of a triangle is 180 degrees and parallel lines continuously maintain the same distance. Measurements from the Wilkinson Microwave Anisotropy Probe have confirmed the universe is flat within a 0.4% margin of error. [2]

In the absence of dark energy, a flat universe expands forever but at a continually decelerating rate, with expansion asymptotically approaching zero. With dark energy, the expansion rate of the universe initially slows, due to the effects of gravity, but eventually increases, and the ultimate fate of the universe becomes the same as that of an open universe.

Theories about the end of the universe

The fate of the universe may be determined by its density. The preponderance of evidence to date, based on measurements of the rate of expansion and the mass density, favors a universe that will continue to expand indefinitely, resulting in the "Big Freeze" scenario below. [16] However, observations are not conclusive, and alternative models are still possible. [17] [ obsolete source ]

Big Freeze or Heat Death

The heat death of the universe, also known as the Big Freeze (or Big Chill), is a scenario under which continued expansion results in a universe that asymptotically approaches absolute zero temperature. [18] Under this scenario, the universe eventually reaches a state of maximum entropy in which everything is evenly distributed and there are no energy gradients—which are needed to sustain information processing, one form of which is life. This scenario has gained ground as the most likely fate. [19]

In this scenario, stars are expected to form normally for 1012 to 1014 (1–100 trillion) years, but eventually the supply of gas needed for star formation will be exhausted. As existing stars run out of fuel and cease to shine, the universe will slowly and inexorably grow darker. Eventually black holes will dominate the universe, but they will disappear over time as they emit Hawking radiation. [20] Over infinite time, there could be a spontaneous entropy decrease by the Poincaré recurrence theorem, thermal fluctuations, [21] [22] and the fluctuation theorem. [23] [24]

The heat death scenario is compatible with any of the three spatial models, but it requires that the universe reaches an eventual temperature minimum. [25] Without dark energy, it could occur only under a flat or hyperbolic geometry. With a positive cosmological constant, it could also occur in a closed universe.

Big Rip

The current Hubble constant defines a rate of acceleration of the universe not large enough to destroy local structures like galaxies, which are held together by gravity, but large enough to increase the space between them. A steady increase in the Hubble constant to infinity would result in all material objects in the universe, starting with galaxies and eventually (in a finite time) all forms, no matter how small, disintegrating into unbound elementary particles, radiation and beyond. As the energy density, scale factor and expansion rate become infinite, the universe ends as what is effectively a singularity.

In the special case of phantom dark energy, which has supposed negative kinetic energy that would result in a higher rate of acceleration than other cosmological constants predict, a more sudden big rip could occur.

Big Crunch

The Big Crunch. The vertical axis can be considered as expansion or contraction with time. Big crunch.png
The Big Crunch. The vertical axis can be considered as expansion or contraction with time.

The Big Crunch hypothesis is a symmetric view of the ultimate fate of the universe. Just as the theorized Big Bang started as a cosmological expansion, this theory assumes that the average density of the universe will be enough to stop its expansion and the universe will begin contracting. The result is unknown; a simple estimation would have all the matter and spacetime in the universe collapse into a dimensionless singularity back into how the universe started with the Big Bang, but at these scales unknown quantum effects need to be considered (see Quantum gravity). Recent evidence suggests that this scenario is unlikely but has not been ruled out, as measurements have been available only over a relatively short period of time and could reverse in the future. [19]

This scenario allows the Big Bang to occur immediately after the Big Crunch of a preceding universe. If this happens repeatedly, it creates a cyclic model, which is also known as an oscillatory universe. The universe could then consist of an infinite sequence of finite universes, with each finite universe ending with a Big Crunch that is also the Big Bang of the next universe. A problem with the cyclic universe is that it does not reconcile with the second law of thermodynamics, as entropy would build up from oscillation to oscillation and cause the eventual heat death of the universe.[ citation needed ] Current evidence also indicates the universe is not closed.[ citation needed ] This has caused cosmologists to abandon the oscillating universe model.[ citation needed ] A somewhat similar idea is embraced by the cyclic model, but this idea evades heat death because of an expansion of the branes that dilutes entropy accumulated in the previous cycle.[ citation needed ]

Big Bounce

The Big Bounce is a theorized scientific model related to the beginning of the known universe. It derives from the oscillatory universe or cyclic repetition interpretation of the Big Bang where the first cosmological event was the result of the collapse of a previous universe.

According to one version of the Big Bang theory of cosmology, in the beginning the universe was infinitely dense. Such a description seems to be at odds with other more widely accepted theories, especially quantum mechanics and its uncertainty principle. [26] Therefore, quantum mechanics has given rise to an alternative version of the Big Bang theory, specifically that the universe tunneled into existence and had a finite density consistent with quantum mechanics, before evolving in a manner governed by classical physics. [26] Also, if the universe is closed, this theory would predict that once this universe collapses it will spawn another universe in an event similar to the Big Bang after a universal singularity is reached or a repulsive quantum force causes re-expansion.

In simple terms, this theory states that the universe will continuously repeat the cycle of a Big Bang, followed by a Big Crunch.

Cosmic uncertainty

Each possibility described so far is based on a simple form for the dark energy equation of state. However, as the name is meant to imply, little is now known about the physics of dark energy. If the theory of inflation is true, the universe went through an episode dominated by a different form of dark energy in the first moments of the Big Bang, but inflation ended, indicating an equation of state more complex than those assumed for present-day dark energy. It is possible that the dark energy equation of state could change again, resulting in an event that would have consequences which are difficult to predict or parameterize. As the nature of dark energy and dark matter remain enigmatic, even hypothetical, the possibilities surrounding their coming role in the universe are unknown.

Other possible fates of the universe

There are also some possible events, such as the Big Slurp, which would seriously harm the universe, although the universe as a whole would not be completely destroyed as a result.

Big Slurp

This theory posits that the universe currently exists in a false vacuum and that it could become a true vacuum at any moment.

In order to best understand the false vacuum collapse theory, one must first understand the Higgs field which permeates the universe. Much like an electromagnetic field, it varies in strength based upon its potential. A true vacuum exists so long as the universe exists in its lowest energy state, in which case the false vacuum theory is irrelevant. However, if the vacuum is not in its lowest energy state (a false vacuum), it could tunnel into a lower-energy state. [27] This is called vacuum decay . This has the potential to fundamentally alter the universe: in some scenarios, even the various physical constants could have different values, severely affecting the foundations of matter, energy, and spacetime. It is also possible that all structures will be destroyed instantaneously, without any forewarning. [28]

However, only a portion of the universe would be destroyed by the Big Slurp while most of the universe would still be unaffected because galaxies located further than 4,200 megaparsecs (13 billion light-years) away from each other are moving away from each other faster than the speed of light while the Big Slurp itself cannot expand faster than the speed of light. [29] To place this in context, the size of the observable universe is currently about 46 billion light years in all directions from earth. [30] The universe is thought to be that size or larger.

Observational constraints on theories

Choosing among these rival scenarios is done by 'weighing' the universe, for example, measuring the relative contributions of matter, radiation, dark matter, and dark energy to the critical density. More concretely, competing scenarios are evaluated against data on galaxy clustering and distant supernovas, and on the anisotropies in the cosmic microwave background.

See also

Related Research Articles

<span class="mw-page-title-main">Big Bang</span> Physical theory

The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. The notion of an expanding universe was first scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations. The earliest empirical observation of the notion of an expanding universe is known as Hubble's Law, published in work by physicist Edwin Hubble in 1929, which discerned that galaxies are moving away from Earth at a rate that accelerates proportionally with distance. Independent of Friedmann's work, and independent of Hubble's observations, physicist Georges Lemaître proposed that the universe emerged from a "primeval atom" in 1931, introducing the modern notion of Big Bang.

<span class="mw-page-title-main">Physical cosmology</span> Branch of cosmology which studies mathematical models of the universe

Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood.

<span class="mw-page-title-main">Cosmic inflation</span> Theory of rapid universe expansion

In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the very early universe. Following the inflationary period, the universe continued to expand, but at a slower rate. The re-acceleration of this slowing expansion due to dark energy began after the universe was already over 7.7 billion years old.

<span class="mw-page-title-main">Cosmological constant</span> Constant representing stress–energy density of the vacuum

In cosmology, the cosmological constant, alternatively called Einstein's cosmological constant, is a coefficient that Albert Einstein initially added to his field equations of general relativity. He later removed it; however, much later it was revived to express the energy density of space, or vacuum energy, that arises in quantum mechanics. It is closely associated with the concept of dark energy.

<span class="mw-page-title-main">Accelerating expansion of the universe</span> Cosmological phenomenon

Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. The accelerated expansion of the universe was discovered in 1998 by two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team, which used distant type Ia supernovae to measure the acceleration. The idea was that as type Ia supernovae have almost the same intrinsic brightness, and since objects that are further away appear dimmer, the observed brightness of these supernovae can be used to measure the distance to them. The distance can then be compared to the supernovae's cosmological redshift, which measures how much the universe has expanded since the supernova occurred; the Hubble law established that the further away an object is, the faster it is receding. The unexpected result was that objects in the universe are moving away from one another at an accelerating rate. Cosmologists at the time expected that recession velocity would always be decelerating, due to the gravitational attraction of the matter in the universe. Three members of these two groups have subsequently been awarded Nobel Prizes for their discovery. Confirmatory evidence has been found in baryon acoustic oscillations, and in analyses of the clustering of galaxies.

In physics, quintessence is a hypothetical form of dark energy, more precisely a scalar field, postulated as an explanation of the observation of an accelerating rate of expansion of the universe. The first example of this scenario was proposed by Ratra and Peebles (1988) and Wetterich (1988). The concept was expanded to more general types of time-varying dark energy, and the term "quintessence" was first introduced in a 1998 paper by Robert R. Caldwell, Rahul Dave and Paul Steinhardt. It has been proposed by some physicists to be a fifth fundamental force. Quintessence differs from the cosmological constant explanation of dark energy in that it is dynamic; that is, it changes over time, unlike the cosmological constant which, by definition, does not change. Quintessence can be either attractive or repulsive depending on the ratio of its kinetic and potential energy. Those working with this postulate believe that quintessence became repulsive about ten billion years ago, about 3.5 billion years after the Big Bang.

<span class="mw-page-title-main">Shape of the universe</span> Local and global geometry of the universe

In physical cosmology, the shape of the universe refers to both its local and global geometry. Local geometry is defined primarily by its curvature, while the global geometry is characterised by its topology. General relativity explains how spatial curvature is constrained by gravity. The global topology of the universe cannot be deduced from measurements of curvature inferred from observations within the family of homogeneous general relativistic models alone, due to the existence of locally indistinguishable spaces with varying global topological characteristics. For example; a multiply connected space like a 3 torus has everywhere zero curvature but is finite in extent, whereas a flat simply connected space is infinite in extent.

<span class="mw-page-title-main">Big Rip</span> Cosmological model

In physical cosmology, the Big Rip is a hypothetical cosmological model concerning the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, and even spacetime itself, is progressively torn apart by the expansion of the universe at a certain time in the future, until distances between particles will infinitely increase.

<span class="mw-page-title-main">Big Crunch</span> Hypothetical scenario for the ultimate fate of the universe

The Big Crunch is a hypothetical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach zero, an event potentially followed by a reformation of the universe starting with another Big Bang. The vast majority of evidence indicates that this hypothesis is not correct. Instead, astronomical observations show that the expansion of the universe is accelerating rather than being slowed by gravity, suggesting that a Big Freeze is more likely. Nonetheless, some physicists have proposed that a "Big Crunch-style" event could result from a dark energy fluctuation.

<span class="mw-page-title-main">Non-standard cosmology</span> Models of the universe which deviate from then-current scientific consensus

A non-standard cosmology is any physical cosmological model of the universe that was, or still is, proposed as an alternative to the then-current standard model of cosmology. The term non-standard is applied to any theory that does not conform to the scientific consensus. Because the term depends on the prevailing consensus, the meaning of the term changes over time. For example, hot dark matter would not have been considered non-standard in 1990, but would have been in 2010. Conversely, a non-zero cosmological constant resulting in an accelerating universe would have been considered non-standard in 1990, but is part of the standard cosmology in 2010.

<span class="mw-page-title-main">Big Bounce</span> Model for the origin of the universe

The Big Bounce hypothesis is a cosmological model for the origin of the known universe. It was originally suggested as a phase of the cyclic model or oscillatory universe interpretation of the Big Bang, where the first cosmological event was the result of the collapse of a previous universe. It receded from serious consideration in the early 1980s after inflation theory emerged as a solution to the horizon problem, which had arisen from advances in observations revealing the large-scale structure of the universe.

<span class="mw-page-title-main">Cyclic model</span> Cosmological models involving indefinite, self-sustaining cycles

A cyclic model is any of several cosmological models in which the universe follows infinite, or indefinite, self-sustaining cycles. For example, the oscillating universe theory briefly considered by Albert Einstein in 1930 theorized a universe following an eternal series of oscillations, each beginning with a Big Bang and ending with a Big Crunch; in the interim, the universe would expand for a period of time before the gravitational attraction of matter causes it to collapse back in and undergo a bounce.

<span class="mw-page-title-main">Lambda-CDM model</span> An anomaly in astronomical observations of the Cosmic Microwave Background

The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components:

  1. a cosmological constant, denoted by lambda (Λ), associated with dark energy
  2. the postulated cold dark matter, denoted by CDM
  3. ordinary matter
<span class="mw-page-title-main">Flatness problem</span> Cosmological fine-tuning problem

The flatness problem is a cosmological fine-tuning problem within the Big Bang model of the universe. Such problems arise from the observation that some of the initial conditions of the universe appear to be fine-tuned to very 'special' values, and that small deviations from these values would have extreme effects on the appearance of the universe at the current time.

<span class="mw-page-title-main">Expansion of the universe</span> Increase in distance between parts of the universe over time

The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it. To any observer in the universe, it appears that all but the nearest galaxies recede at speeds that are proportional to their distance from the observer, on average. While objects cannot move faster than light, this limitation applies only with respect to local reference frames and does not limit the recession rates of cosmologically distant objects.

<span class="mw-page-title-main">Future of an expanding universe</span> Future scenario if the expansion of the universe will continue forever or not

Current observations suggest that the expansion of the universe will continue forever. The prevailing theory is that the universe will cool as it expands, eventually becoming too cold to sustain life. For this reason, this future scenario once popularly called "Heat Death" is now known as the "Big Chill" or "Big Freeze".

<span class="mw-page-title-main">Chronology of the universe</span> History and future of the universe

The chronology of the universe describes the history and future of the universe according to Big Bang cosmology.

<span class="mw-page-title-main">Dark energy</span> Energy driving the accelerated expansion of the universe

In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe. Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density is very low: 7×10−30 g/cm3, much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass–energy content because it is uniform across space.

<span class="mw-page-title-main">Cosmological constant problem</span> Concept in cosmology

In cosmology, the cosmological constant problem or vacuum catastrophe is the substantial disagreement between the observed values of vacuum energy density and the much larger theoretical value of zero-point energy suggested by quantum field theory.

<span class="mw-page-title-main">Black hole cosmology</span> Cosmological model in which the observable universe is the interior of a black hole

A black hole cosmology is a cosmological model in which the observable universe is the interior of a black hole. Such models were originally proposed by theoretical physicist Raj Kumar Pathria, and concurrently by mathematician I. J. Good.

References

  1. ↑ Wollack, Edward J. (10 December 2010). "Cosmology: The Study of the Universe". Universe 101: Big Bang Theory. NASA. Archived from the original on 14 May 2011. Retrieved 27 April 2011.
  2. 1 2 3 "WMAP – Shape of the Universe". map.gsfc.nasa.gov.
  3. 1 2 "WMAP – Fate of the Universe". map.gsfc.nasa.gov.
  4. 1 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. 47: 49–56. Bibcode:1927ASSB...47...49L.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 (5): 483–490. Bibcode:1931MNRAS..91..483L. doi: 10.1093/mnras/91.5.483 .
  5. ↑ Did Einstein Predict Dark Energy?, hubblesite.org.
  6. ↑ Kirshner, Robert P. (13 April 1999). "Supernovae, an accelerating universe and the cosmological constant". Proceedings of the National Academy of Sciences. 96 (8): 4224–4227. Bibcode:1999PNAS...96.4224K. doi: 10.1073/pnas.96.8.4224 . PMC   33557 . PMID   10200242.
  7. ↑ Falk, Dan (2023-10-05). "The 'least crazy' idea: Early dark energy could solve a cosmological conundrum". Astronomy Magazine. Retrieved 2023-11-14.
  8. ↑ "Euclid overview". www.esa.int. Retrieved 2023-11-14.
  9. ↑ "Dark Energy, Dark Matter – Science Mission Directorate". science.nasa.gov.
  10. ↑ Ryden, Barbara. Introduction to Cosmology. The Ohio State University. p. 56.
  11. ↑ Tegmark, Max (2014). Our Mathematical Universe: My Quest for the Ultimate Nature of Reality (1 ed.). Knopf. ISBN   978-0307599803.
  12. ↑ Caldwell, Robert R.; Kamionkowski, Marc (2009). "The Physics of Cosmic Acceleration". Annu. Rev. Nucl. Part. Sci. 59 (1): 397–429. arXiv: 0903.0866 . Bibcode:2009ARNPS..59..397C. doi:10.1146/annurev-nucl-010709-151330. S2CID   16727077.
  13. ↑ Caldwell, R. R.; Dave, R.; Steinhardt, P. J. (1998). "Cosmological Imprint of an Energy Component with General Equation-of-State". Physical Review Letters. 80 (8): 1582–1585. arXiv: astro-ph/9708069 . Bibcode:1998PhRvL..80.1582C. doi:10.1103/PhysRevLett.80.1582. S2CID   597168.
  14. ↑ Caldwell, Robert R. (2002). "A phantom menace? Cosmological consequences of a dark energy component with super-negative equation of state". Physics Letters B. 545 (1–2): 23–29. arXiv: astro-ph/9908168 . Bibcode:2002PhLB..545...23C. doi:10.1016/S0370-2693(02)02589-3. S2CID   9820570.
  15. ↑ Caldwell, Robert R.; Kamionkowski, Marc; Weinberg, Nevin N. (2003). "Phantom Energy and Cosmic Doomsday". Physical Review Letters. 91 (7): 071301. arXiv: astro-ph/0302506 . Bibcode:2003PhRvL..91g1301C. doi:10.1103/PhysRevLett.91.071301. PMID   12935004. S2CID   119498512.
  16. ↑ "WMAP – Fate of the Universe". map.gsfc.nasa.gov. Retrieved 2023-06-15.
  17. ↑ Lehners, Jean-Luc; Steinhardt, Paul J.; Turok, Neil (2009). "The Return of the Phoenix Universe". International Journal of Modern Physics D. 18 (14): 2231–2235. arXiv: 0910.0834 . Bibcode:2009IJMPD..18.2231L. doi:10.1142/S0218271809015977. S2CID   119257111.
  18. ↑ Glanz, James (1998). "Breakthrough of the year 1998. Astronomy: Cosmic Motion Revealed". Science. 282 (5397): 2156–2157. Bibcode:1998Sci...282.2156G. doi:10.1126/science.282.5397.2156a. S2CID   117807831.
  19. 1 2 Wang, Yun; Kratochvil, Jan Michael; Linde, Andrei; Shmakova, Marina (2004). "Current observational constraints on cosmic doomsday". Journal of Cosmology and Astro-Particle Physics. 2004 (12): 006. arXiv: astro-ph/0409264 . Bibcode:2004JCAP...12..006W. doi:10.1088/1475-7516/2004/12/006. S2CID   56436935.
  20. ↑ Adams, Fred C.; Laughlin, Gregory (1997). "A dying universe: the long-term fate and evolution of astrophysical objects". Reviews of Modern Physics. 69 (2): 337–372. arXiv: astro-ph/9701131 . Bibcode:1997RvMP...69..337A. doi:10.1103/RevModPhys.69.337. S2CID   12173790.
  21. ↑ Tegmark, Max (May 2003). "Parallel Universes". Scientific American. 288 (5): 40–51. arXiv: astro-ph/0302131 . Bibcode:2003SciAm.288e..40T. doi:10.1038/scientificamerican0503-40. PMID   12701329.
  22. ↑ Werlang, T.; Ribeiro, G. A. P.; Rigolin, Gustavo (2013). "Interplay Between Quantum Phase Transitions and the Behavior of Quantum Correlations at Finite Temperatures". International Journal of Modern Physics B. 27: 1345032. arXiv: 1205.1046 . Bibcode:2013IJMPB..2745032W. doi:10.1142/S021797921345032X. S2CID   119264198.
  23. ↑ Xing, Xiu-San; Steinhardt, Paul J.; Turok, Neil (2007). "Spontaneous entropy decrease and its statistical formula". arXiv: 0710.4624 [cond-mat.stat-mech].
  24. ↑ Linde, Andrei (2007). "Sinks in the landscape, Boltzmann brains and the cosmological constant problem". Journal of Cosmology and Astroparticle Physics. 2007 (1): 022. arXiv: hep-th/0611043 . Bibcode:2007JCAP...01..022L. CiteSeerX   10.1.1.266.8334 . doi:10.1088/1475-7516/2007/01/022. S2CID   16984680.
  25. ↑ Yurov, A. V.; Astashenok, A. V.; González-Díaz, P. F. (2008). "Astronomical bounds on a future Big Freeze singularity". Gravitation and Cosmology. 14 (3): 205–212. arXiv: 0705.4108 . Bibcode:2008GrCo...14..205Y. doi:10.1134/S0202289308030018. S2CID   119265830.
  26. 1 2 Halliwell, J. J. (1991). "Quantum cosmology and the creation of the universe". Scientific American. 265 (6): 76, 85. Bibcode:1991SciAm.265f..28H. doi:10.1038/scientificamerican1291-76.
  27. ↑
  28. ↑ Hawking, Stephen W. & Moss, I. G. (1982). "Supercooled phase transitions in the very early universe". Physics Letters B. 110 (1): 35–38. Bibcode:1982PhLB..110...35H. doi:10.1016/0370-2693(82)90946-7.
  29. ↑ Cain, Fraser; Today, Universe. "How are galaxies moving away faster than light?". phys.org. Retrieved 2023-06-15.
  30. ↑ Crane, Leah (29 June 2024). de Lange, Catherine (ed.). "How big is the universe, really?". New Scientist. p. 31.

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