Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
Ultimate fate of the universe

Ultimate fate of the universe

Overview
The ultimate fate of the universe is a topic in physical cosmology
Physical cosmology
Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. For most of human history, it was a branch of metaphysics and religion...

. Many possible fates are predicted by rival scientific theories, including futures of both finite and infinite duration.

Once the notion that the universe started with a rapid inflation nicknamed the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 became accepted by the majority of scientists, the ultimate fate of the universe became a valid cosmological question, one depending upon the physical properties of the mass/energy in the universe, its average density, and the rate of expansion.


The theoretical scientific exploration of the ultimate fate of the universe became possible with Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

's 1916 theory of general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

.
Discussion
Ask a question about 'Ultimate fate of the universe'
Start a new discussion about 'Ultimate fate of the universe'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Recent Discussions
Encyclopedia
The ultimate fate of the universe is a topic in physical cosmology
Physical cosmology
Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. For most of human history, it was a branch of metaphysics and religion...

. Many possible fates are predicted by rival scientific theories, including futures of both finite and infinite duration.

Once the notion that the universe started with a rapid inflation nicknamed the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 became accepted by the majority of scientists, the ultimate fate of the universe became a valid cosmological question, one depending upon the physical properties of the mass/energy in the universe, its average density, and the rate of expansion.

Theory



The theoretical scientific exploration of the ultimate fate of the universe became possible with Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

's 1916 theory of general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

. General relativity can be employed to describe the universe on the largest possible scale. There are many possible solutions to the equations of general relativity, and each solution implies a possible ultimate fate of the universe. Alexander Friedman proposed a number of such solution
Friedmann equations
The Friedmann equations are a set of equations in physical cosmology that govern the expansion of space in homogeneous and isotropic models of the universe within the context of general relativity...

s in 1922 as did Georges Lemaître
Georges Lemaître
Monsignor Georges Henri Joseph Édouard Lemaître was a Belgian priest, astronomer and professor of physics at the Catholic University of Louvain. He was the first person to propose the theory of the expansion of the Universe, widely misattributed to Edwin Hubble...

 in 1927. In some of these the universe has been expanding
Metric expansion of space
The metric expansion of space is the increase of distance between distant parts of the universe with time. It is an intrinsic expansion—that is, it is defined by the relative separation of parts of the universe and not by motion "outward" into preexisting space...

 from an initial singularity
Gravitational singularity
A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system...

; this is, essentially, the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

.

Observation


In 1931, Edwin Hubble
Edwin Hubble
Edwin Powell Hubble was an American astronomer who profoundly changed the understanding of the universe by confirming the existence of galaxies other than the Milky Way - our own galaxy...

 published his conclusion, based on his observations of Cepheid variable
Cepheid variable
A Cepheid is a member of a class of very luminous variable stars. The strong direct relationship between a Cepheid variable's luminosity and pulsation period, secures for Cepheids their status as important standard candles for establishing the Galactic and extragalactic distance scales.Cepheid...

 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
Georges Lemaître
Monsignor Georges Henri Joseph Édouard Lemaître was a Belgian priest, astronomer and professor of physics at the Catholic University of Louvain. He was the first person to propose the theory of the expansion of the Universe, widely misattributed to Edwin Hubble...

 set out a theory that has since come to be called the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 theory of the origin of the universe. In 1948, Fred Hoyle
Fred Hoyle
Sir Fred Hoyle FRS was an English astronomer and mathematician noted primarily for his contribution to the theory of stellar nucleosynthesis and his often controversial stance on other cosmological and scientific matters—in particular his rejection of the "Big Bang" theory, a term originally...

 set out his opposing steady state theory
Steady State theory
In cosmology, the Steady State theory is a model developed in 1948 by Fred Hoyle, Thomas Gold, Hermann Bondi and others as an alternative to the Big Bang 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 Penzias and Robert Wilson
Robert Woodrow Wilson
For the American President, see Woodrow Wilson.Robert Woodrow Wilson is an American astronomer, 1978 Nobel laureate in physics, who with Arno Allan Penzias discovered in 1964 the cosmic microwave background radiation...

, of the cosmic microwave background radiation
Cosmic microwave background radiation
In cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....

, 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


When Einstein formulated general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

, he and his contemporaries believed in a static universe. When Einstein found that his equations could easily be solved in such a way as to allow the universe to be expanding now, and to contract in the far future, he added to those equations what he called a cosmological constant
Cosmological constant
In physical cosmology, the cosmological constant was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe...

, 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. After Hubble announced his conclusion that the universe was expanding, Einstein wrote that his cosmological constant was "the greatest blunder of my life".

Density parameter


An important parameter in fate of the universe theory is the Density parameter, Omega (Ω), defined as the average matter density of the universe divided by a critical value of that density. This selects one of three possible geometries
Shape of the Universe
The shape of the universe is a matter of debate in physical cosmology over the local and global geometry of the universe which considers both curvature and topology, though, strictly speaking, it goes beyond both...

 depending on whether Ω is equal to, less than, or greater than 1. 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
Spacetime
In physics, spacetime is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space as being three-dimensional and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions...

 caused by smaller clumps of mass (for example, galaxies and star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s). If the primary content of the universe is inert matter, as in the dust models
Dust solution
In general relativity, a dust solution is an exact solution of the Einstein field equation in which the gravitational field is produced entirely by the mass, momentum, and stress density of a perfect fluid which has positive mass density but vanishing pressure...

 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 Ω, or equivalently the rate at which the expansion was decelerating.

Repulsive force


Starting in 1998, observations of supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

e in distant galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

 have been interpreted as consistent with a universe whose expansion is accelerating
Accelerating universe
The accelerating universe is the observation that the universe appears to be expanding at an increasing rate, which in formal terms means that the cosmic scale factor a has a positive second derivative, implying that the velocity at which a given galaxy is receding from us should be continually...

. Subsequent cosmological theorizing has been designed so as to allow for this possible acceleration, nearly always by invoking dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

, which in its simplest form is just a positive cosmological constant. In general dark energy is a catch-all term for any hypothesised field with negative pressure, usually with a density that changes as the universe expands.

Role of the shape of the universe


The current scientific consensus of most cosmologists is that the ultimate fate of the universe depends on its overall shape, how much dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

 it contains, and on the equation of state
Equation of state (cosmology)
In cosmology, the equation of state of a perfect fluid is characterized by a dimensionless number \! w, equal to the ratio of its pressure \! p to its energy density \! \rho: \! w=p/\rho...

 which determines how the dark energy density responds to the expansion of the universe. Recent observations have shown that, from 7.5 billion years
Graphical timeline of the Big Bang
This timeline of the Big Bang shows the sequence of events as predicted by the Big Bang theory, from the beginning of time to the end of the Dark Ages....

 after the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 onwards, the expansion rate of the universe has actually been increasing, commensurate with the Open Universe theory.

Closed universe


If , then 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
Elliptic geometry
Elliptic geometry is a non-Euclidean geometry, in which, given a line L and a point p outside L, there exists no line parallel to L passing through p. Elliptic geometry, like hyperbolic geometry, violates Euclid's parallel postulate, which can be interpreted as asserting that there is exactly one...

.

In a closed universe lacking the repulsive effect of dark energy, 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
Big Crunch
In physical cosmology, the Big Crunch is one possible scenario for the ultimate fate of the universe, in which the metric expansion of space eventually reverses and the universe recollapses, ultimately ending as a black hole singularity.- Overview :...

", by analogy with Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

. However, if the universe has a significant amount of dark energy that will be used as an infinite force, then the expansion of the universe can continue forever—even if .

Open universe


If , the geometry of space is open
Shape of the Universe
The shape of the universe is a matter of debate in physical cosmology over the local and global geometry of the universe which considers both curvature and topology, though, strictly speaking, it goes beyond both...

, 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
Hyperbolic geometry
In mathematics, hyperbolic geometry is a non-Euclidean geometry, meaning that the parallel postulate of Euclidean geometry is replaced...

.

Even without dark energy, a negatively curved universe expands forever, with gravity barely slowing the rate of expansion. With dark energy, the expansion not only continues but accelerates. The ultimate fate of an open universe is either universal heat death
Heat death of the universe
The heat death of the universe is a suggested ultimate fate of the universe, in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain motion or life. Heat death does not imply any particular absolute temperature; it only requires that...

, the "Big Freeze", or the "Big Rip
Big Rip
The Big Rip is a cosmological hypothesis first published in 2003, about the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, is progressively torn apart by the expansion of the universe at a certain time in the future...

", where the acceleration caused by dark energy eventually becomes so strong that it completely overwhelms the effects of the gravitational, electromagnetic
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...

 and strong binding forces.

Conversely, a negative cosmological constant
Cosmological constant
In physical cosmology, the cosmological constant was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe...

, which would correspond to a negative energy density and positive pressure, would cause even an open universe to recollapse to a big crunch. This option has been ruled out by observations.

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
Euclidean geometry
Euclidean geometry is a mathematical system attributed to the Alexandrian Greek mathematician Euclid, which he described in his textbook on geometry: the Elements. Euclid's method consists in assuming a small set of intuitively appealing axioms, and deducing many other propositions from these...

, the sum of the angles of a triangle is 180 degrees and parallel lines continuously maintain the same distance.

Absent dark energy, a flat universe expands forever but at a continually decelerating rate, with expansion asymptotically approaching zero. With dark energy, the expansion rate of the universe initially slows down, due to the effect of gravity, but eventually increases. The ultimate fate of the universe is the same as an open universe.

Theories about the end of the universe


The fate of the universe is determined by the density of the universe. 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. However, new understandings of the nature of dark matter also suggest its interactions with mass and gravity demonstrate the possibility of an oscillating universe.

Big Freeze or heat death



The Big Freeze is a scenario under which continued expansion results in a universe that asymptotically
Asymptote
In analytic geometry, an asymptote of a curve is a line such that the distance between the curve and the line approaches zero as they tend to infinity. Some sources include the requirement that the curve may not cross the line infinitely often, but this is unusual for modern authors...

 approaches absolute zero
Absolute zero
Absolute zero is the theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached using only thermodynamic means....

 temperature. It could, in the absence of dark energy, occur only under a flat or hyperbolic geometry. With a positive cosmological constant, it could also occur in a closed universe. This scenario is currently the most commonly accepted theory within the scientific community. A related scenario is heat death
Heat death of the universe
The heat death of the universe is a suggested ultimate fate of the universe, in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain motion or life. Heat death does not imply any particular absolute temperature; it only requires that...

, which states that the universe goes to a state of maximum entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...

 in which everything is evenly distributed, and there are no gradient
Gradient
In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....

s — which are needed to sustain information processing
Information processing
Information processing is the change of information in any manner detectable by an observer. As such, it is a process which describes everything which happens in the universe, from the falling of a rock to the printing of a text file from a digital computer system...

, one form of which is life
Life
Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes from those that do not, either because such functions have ceased , or else because they lack such functions and are classified as inanimate...

. The heat death scenario is compatible with any of the three spatial models, but requires that the universe reach an eventual temperature
minimum.

Big Rip



In the special case of phantom dark energy
Phantom energy
Phantom energy is a hypothetical form of dark energy with equation of state \! w Phantom energy is a hypothetical form of dark energy with equation of state...

, which has even more negative pressure than a simple cosmological constant, the density of dark energy increases with time, causing the rate of acceleration to increase, leading to a steady increase in the Hubble constant. As a result, all material objects in the universe, starting with galaxies and eventually (in a finite time) all forms, no matter how small, will disintegrate into unbound elementary particles and radiation, ripped apart by the phantom energy force and shooting apart from each other. The end state of the universe is a singularity, as the dark energy density and expansion rate becomes infinite. For a possible timeline based on current physical theories, see 1 E19 s and more.

Big Crunch




The Big Crunch theory is a symmetric view of the ultimate fate of the Universe. Just as the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 started a cosmological expansion, this theory assumes that the average density of the universe is enough to stop its expansion and begin contracting. The end result is unknown; a simple estimation would have all the matter and space-time in the universe collapse into a dimensionless singularity
Gravitational singularity
A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system...

, but at these scales unknown quantum effects need to be considered (see Quantum gravity
Quantum gravity
Quantum gravity is the field of theoretical physics which attempts to develop scientific models that unify quantum mechanics with general relativity...

).

This scenario allows the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 to have been immediately preceded by the Big Crunch
Big Crunch
In physical cosmology, the Big Crunch is one possible scenario for the ultimate fate of the universe, in which the metric expansion of space eventually reverses and the universe recollapses, ultimately ending as a black hole singularity.- Overview :...

 of a preceding universe. If this occurs repeatedly, we have an oscillatory universe which is also known as cyclic universe. The universe could then consist of an infinite sequence of finite universes, each finite universe ending with a Big Crunch that is also the Big Bang of the next universe. Theoretically, the cyclic universe could not be reconciled with the second law of thermodynamics
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...

: entropy would build up from oscillation to oscillation and cause heat death. Other measurements suggested the universe is not closed
Shape of the Universe
The shape of the universe is a matter of debate in physical cosmology over the local and global geometry of the universe which considers both curvature and topology, though, strictly speaking, it goes beyond both...

. These arguments caused cosmologists to abandon the oscillating universe model. A somewhat similar idea is embraced by the cyclic model
Cyclic model
A cyclic model is any of several cosmological models in which the universe follows infinite, 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...

, but this idea evades heat death, because of an expansion of the branes
Membrane (M-Theory)
In theoretical physics, a membrane, brane, or p-brane is a spatially extended mathematical concept that appears in string theory and related theories...

 that dilutes entropy accumulated in the previous cycle.

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 had infinite density. Such a description seems to be at odds with everything else in physics, and especially quantum mechanics and its uncertainty principle
Uncertainty principle
In quantum mechanics, the Heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known...

. It is not surprising, therefore, that quantum mechanics has given rise to an alternative version of the Big Bang theory. 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.

Multiverse: no complete end



One multiverse hypothesis states that our uni-"verse" is merely one Big Bang among an infinite number of simultaneously expanding Big Bangs that are spread out over endless distances (open space).

Each "verse" may be either matter or antimatter, with an equal number in existence at any given time. As the "verses" expand they collide and matter and antimatter annihilate, releasing energy. Heat death of a finite universe would be predicted as entropy increases; however, the infinite size of the multiverse and the infinite number of "verses" could mean that new "verses" would be formed as old "verses" were annihilated.

A chain reaction multiverse would be analogous to a fireworks display (each explosion representing a Big Bang) that starts in one neighborhood and is followed by fireworks displays in surrounding neighborhoods and then in neighborhoods further out. The chain reaction of Big Bangs would continue to expand as Big Bang fuel is consumed. If the multiverse is open and the fuel is infinite then the chain reaction would expand forever. Of course, it is not known what the "fuel" is, but it is logical to assume that matter and energy are the product of a transformation from a real reactant, possibly the Higgs boson
Higgs boson
The Higgs boson is a hypothetical massive elementary particle that is predicted to exist by the Standard Model of particle physics. Its existence is postulated as a means of resolving inconsistencies in the Standard Model...

.

The multiverse as a whole may never end completely.

False vacuum


If the vacuum is not in its lowest energy state (a false vacuum
False vacuum
In quantum field theory, a false vacuum is a metastable sector of space that appears to be a perturbative vacuum, but is unstable due to instanton effects that may tunnel to a lower energy state. This tunneling can be caused by quantum fluctuations or the creation of high-energy particles...

), it could tunnel
Quantum tunnelling
Quantum tunnelling refers to the quantum mechanical phenomenon where a particle tunnels through a barrier that it classically could not surmount. This plays an essential role in several physical phenomena, such as the nuclear fusion that occurs in main sequence stars like the sun, and has important...

 into a lower energy state. This is called the vacuum metastability event. This has the potential to fundamentally alter our universe; in more audacious scenarios even the various physical constant
Physical constant
A physical constant is a physical quantity that is generally believed to be both universal in nature and constant in time. It can be contrasted with a mathematical constant, which is a fixed numerical value but does not directly involve any physical measurement.There are many physical constants in...

s could have different values, severely affecting the foundations of matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...

, energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

, and spacetime
Spacetime
In physics, spacetime is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space as being three-dimensional and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions...

. It is also possible that all structures will be destroyed instantaneously, without any forewarning.

According to the many-worlds interpretation
Many-worlds interpretation
The many-worlds interpretation is an interpretation of quantum mechanics that asserts the objective reality of the universal wavefunction, but denies the actuality of wavefunction collapse. Many-worlds implies that all possible alternative histories and futures are real, each representing an...

 of quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

, the universe will not end this way. Instead, each time a quantum event happens that causes the universe to decay from a false vacuum to a true vacuum state
Vacuum state
In quantum field theory, the vacuum state is the quantum state with the lowest possible energy. Generally, it contains no physical particles...

, the universe splits into several new worlds. In some of the new worlds the universe decays; in some others the universe continues as before.

Cosmic uncertainty


Each possibility described so far is based on a very simple form for the dark energy equation of state. But as the name is meant to imply, we know almost nothing of the real physics of the dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

. 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 much more complicated than those assumed so far 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 extremely difficult to parametrize or predict. It is also possible the universe may never have an end and continue in its present state forever.

Observational constraints on theories


Choosing among these rival scenarios is done by 'weighing' the universe, for example, measuring the relative contributions of matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...

, radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

, dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 and dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

 to the critical density. More concretely, competing scenarios are evaluated against data on galaxy clustering and distant supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

e, and on the anisotropies in the Cosmic Microwave Background.

Life in a mortal universe


Dyson's eternal intelligence
Dyson's eternal intelligence
Dyson's eternal intelligence is a concept that states an intelligent being would be able to think an infinite number of thoughts in an open universe....

 hypothesis proposes that an advanced civilization could survive for an effectively infinite period of time while consuming only a finite amount of energy. Such a civilization would alternate brief periods of activity with ever longer periods of hibernation.

Recent work in inflationary cosmology
Cosmic inflation
In physical cosmology, cosmic inflation, cosmological inflation or just inflation is the theorized extremely rapid exponential expansion of the early universe by a factor of at least 1078 in volume, driven by a negative-pressure vacuum energy density. The inflationary epoch comprises the first part...

, string theory
String theory
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...

, and quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

 has moved the discussion of the ultimate fate of the universe in directions distinct from the scenarios set out by Dyson. Theoretical work by Eric Chaisson
Eric Chaisson
Eric J. Chaisson is an American astrophysicist and science educator best known for his research, teaching, and writing on the interdisciplinary science of cosmic evolution....

 finds that an expanding spacetime
Spacetime
In physics, spacetime is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space as being three-dimensional and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions...

 gives rise to an increasing "entropy gap", casting doubt on the heat death hypothesis
Heat death of the universe
The heat death of the universe is a suggested ultimate fate of the universe, in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain motion or life. Heat death does not imply any particular absolute temperature; it only requires that...

. Invoking Ilya Prigogine
Ilya Prigogine
Ilya, Viscount Prigogine was a Russian-born naturalized Belgian physical chemist and Nobel Laureate noted for his work on dissipative structures, complex systems, and irreversibility.-Biography :...

's work on far-from-equilibrium thermodynamics, their analysis suggests that this entropy gap may contribute to information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

, and hence to the formation of structure.

Meanwhile, Andrei Linde
Andrei Linde
Andrei Dmitriyevich Linde is a Russian-American theoretical physicist and professor of Physics at Stanford University. Dr. Linde is best known for his work on the concept of the inflationary universe. He received his Bachelor of Science degree from Moscow State University. In 1975, Linde was...

, Alan Guth
Alan Guth
Alan Harvey Guth is an American theoretical physicist and cosmologist. Guth has researched elementary particle theory...

, Ted Harrison
Edward Robert Harrison
Edward R. Harrison was a British astronomer and cosmologist, who spent much of his career at the University of Massachusetts and University of Arizona...

, and Ernest Sternglass  argue that inflationary cosmology strongly suggests the presence of a multiverse
Multiverse
The multiverse is the hypothetical set of multiple possible universes that together comprise all of reality.Multiverse may also refer to:-In fiction:* Multiverse , the fictional multiverse used by DC Comics...

, and that it would be practical even with today's knowledge for intelligent beings to generate and transmit de novo information into a distinct universe. Alan Guth
Alan Guth
Alan Harvey Guth is an American theoretical physicist and cosmologist. Guth has researched elementary particle theory...

 has speculated that a civilization at the top of the Kardashev scale
Kardashev scale
The Kardashev scale is a method of measuring an advanced civilization's level of technological advancement. The scale is only theoretical and in terms of an actual civilization highly speculative; however, it puts energy consumption of an entire civilization in a cosmic perspective. It was first...

 might create fine-tuned universe
Fine-tuned universe
The fine-tuned universe is the proposition that the conditions that allow life in the Universe can only occur when certain universal fundamental physical constants lie within a very narrow range, so that if any of several fundamental constants were only slightly different the universe would be...

s in a continuation of the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

ary drive to exist, grow, and multiply. This has been further developed by the Selfish Biocosm Hypothesis, and by the proposal that the existence of the fundamental physical constants may be subject to a kind of cosmological natural selection. Moreover, recent theoretical work on the unresolved quantum gravity
Quantum gravity
Quantum gravity is the field of theoretical physics which attempts to develop scientific models that unify quantum mechanics with general relativity...

 problem and the holographic principle
Holographic principle
The holographic principle is a property of quantum gravity and string theories which states that the description of a volume of space can be thought of as encoded on a boundary to the region—preferably a light-like boundary like a gravitational horizon...

 suggests that traditional physical quantities may possibly themselves be describable in terms of exchanges of information, which in turn raises questions about the applicability of older cosmological models.

In science fiction


Scientific speculation about the ultimate fate of life in the universe merges almost seamlessly into science fiction. Many works describe the end of the universe—occasionally purely educational exercises describing theories of the day, more often exploiting its potential as the ultimate sense of wonder
Sense of wonder
A sense of wonder is an intellectual and emotional state frequently invoked in discussions of science fiction. It is an emotional reaction to the reader suddenly confronting, understanding, or seeing a concept anew in the context of new information....

 plot device, or satirising the pretensions of humanity in general and cosmologists in particular. Science fiction can try to suggest a scientific eschatology that searches for meaning in the face of the new knowledge. Countless sci-fi and fantasy
Fantasy
Fantasy is a genre of fiction that commonly uses magic and other supernatural phenomena as a primary element of plot, theme, or setting. Many works within the genre take place in imaginary worlds where magic is common...

 works use the threatened destruction of the universe as their plot device, usually with an evil supervillain and/or the incompetence of humanity as the cause, and usually with human ingenuity saving the day.

The topic of heat death was explored in science fiction as early as 1895 in H. G. Wells
H. G. Wells
Herbert George Wells was an English author, now best known for his work in the science fiction genre. He was also a prolific writer in many other genres, including contemporary novels, history, politics and social commentary, even writing text books and rules for war games...

' The Time Machine
The Time Machine
The Time Machine is a science fiction novella by H. G. Wells, published in 1895 for the first time and later adapted into at least two feature films of the same name, as well as two television versions, and a large number of comic book adaptations. It indirectly inspired many more works of fiction...

, which includes an evocation of the heat death of the universe as imagined by scientists like Lord Kelvin at that time, consisting of the fading out of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 to an exhausted red ember and a vision of Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 as a cold and bland eroded desert, to as recently as 2007 in the Doctor Who
Doctor Who
Doctor Who is a British science fiction television programme produced by the BBC. The programme depicts the adventures of a time-travelling humanoid alien known as the Doctor who explores the universe in a sentient time machine called the TARDIS that flies through time and space, whose exterior...

 episode Utopia
Utopia (Doctor Who)
"Utopia" is an episode of the British science fiction television series Doctor Who. It was broadcast on BBC One on 16 June 2007 and is the eleventh episode of series three of the revived Doctor Who series...

, with the last remnants of society struggling to survive in a universe without stars and few planets still capable of supporting life.

Religion is not wholly excluded from science fiction's explorations of the end of our universe. Olaf Stapledon
Olaf Stapledon
William Olaf Stapledon was a British philosopher and author of several influential works of science fiction.-Life:...

's 1937 science fiction novel Star Maker
Star Maker
-External links:*...

describes intelligent life in the far future in each galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

 merging into hive mind
Group mind (science fiction)
A group mind, hive mind or group ego in science fiction is a single consciousness occupying many bodies. Its use in literature goes back at least as far as Olaf Stapledon's science fiction novel Last and First Men ....

-like Galactic Minds which themselves finally merge into a Cosmic Mind which, ascending into hyperspace
Hyperspace (science fiction)
Hyperspace is a plot device sometimes used in science fiction. It is typically described as an alternative region of space co-existing with our own universe which may be entered using an energy field or other device...

, encounters God
God
God is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....

 (the Star Maker). The "Star Maker" reveals to the "Cosmic Mind" a vision of the simpler Cosmoses He created in the past and of those more complex Cosmoses He will create in the future. Arthur C. Clarke
Arthur C. Clarke
Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...

's 1953 short story "The Nine Billion Names of God
The Nine Billion Names of God
"The Nine Billion Names of God" is a 1953 science fiction short story by Arthur C. Clarke. The story was the winner of the retrospective Hugo Award for Best Short Story for the year 1954.-Plot summary:...

" treats non-scientific eschatology seriously. Its famous last line ominously chronicles the end of the universe as observed by mankind: Overhead, without any fuss, the stars were going out..

James Blish
James Blish
James Benjamin Blish was an American author of fantasy and science fiction. Blish also wrote literary criticism of science fiction using the pen-name William Atheling, Jr.-Biography:...

's Cities in Flight
Cities in Flight
Cities in Flight is an omnibus volume of four novels written by James Blish, originally published between 1955 and 1962, which became known over time collectively as the 'Okie' novels. The novels feature entire cities that are able to fly through space using an anti-gravity device, the spindizzy...

series of books (1955 and 1962) ends with the disruption of the Universe in accordance with the hypercollision theory. The protagonists are able to 'seed' the resultant new universes with their own bodies (dying in the process) by using technology which isolates them from local space-time at the instant of the collision.

Isaac Asimov
Isaac Asimov
Isaac Asimov was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular science books. Asimov was one of the most prolific writers of all time, having written or edited more than 500 books and an estimated 90,000...

's short story, "The Last Question
The Last Question
"The Last Question" is a science fiction short story by Isaac Asimov. It first appeared in the November 1956 issue of Science Fiction Quarterly and was reprinted in the collections Nine Tomorrows , The Best of Isaac Asimov , Robot Dreams , the retrospective Opus 100 , and in Isaac Asimov: The...

" was published in 1956. The story is broken up into several segments, with each segment revolving around an artificial, evolving supercomputer. In each segment, humans pose the question "Can entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...

 be reversed?" to the computer, to which the computer responds, "There is Insufficient Data for a Meaningful Answer." At the end of the story, humankind has long since succumbed to heat death (the only cosmological end-scenario articulated at the time). The evolving super-computer, now having evolved to the point where it existed without physical form in hyperspace, finally discovers how to reverse the process and with the proclamation "'LET THERE BE LIGHT!
Let there be light
"Let there be light" is an English translation of the Hebrew יְהִי אוֹר . Other translations of the same phrase include the Latin phrase fiat lux, and the Greek phrase γενηθήτω φῶς . The phrase is often used for its metaphorical meaning of dispelling ignorance.The phrase comes from the third verse...

' And there was light—" the story ends.

Piers Anthony
Piers Anthony
Piers Anthony Dillingham Jacob is an English American writer in the science fiction and fantasy genres, publishing under the name Piers Anthony. He is most famous for his long-running novel series set in the fictional realm of Xanth.Many of his books have appeared on the New York Times Best...

's soft science fiction novel Ghost, deals with the topic of an energy-poor future humanity struggling to find every energy resource possible, and deals with the eventual dying of a universe. In the novel, near limitless energy is able to be found by effectively cannibalizing dead galaxies from other dead universes. Even though the novel does not necessarily give a plausible scientific answer, it does bring up the question of what happens when a galaxy's central black hole becomes so massive that not even gravity can escape it, and what happens when a black hole's event horizon is so far from the central point that it does not have significant gravitational effects. The title of the book, "Ghost" refers to the remains of such a devoured galaxy.

The Big Crunch
Big Crunch
In physical cosmology, the Big Crunch is one possible scenario for the ultimate fate of the universe, in which the metric expansion of space eventually reverses and the universe recollapses, ultimately ending as a black hole singularity.- Overview :...

 as the fate of the Universe was also explored in Poul Anderson
Poul Anderson
Poul William Anderson was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century. Anderson also authored several works of fantasy, historical novels, and a prodigious number of short stories...

's 1970 novel Tau Zero
Tau Zero
Tau Zero is a hard science fiction novel by Poul Anderson. The novel was based upon the short story "To Outlive Eternity" appearing in Galaxy Science Fiction in 1967. It was first published in book form in 1970....

which posits a cyclic universe where the big crunch will be surrounded by a cloud of hydrogen, and that a starship could navigate a course to avoid the singularity and emerge into the new universe after the subsequent big bang.

The plot of Spider Robinson's Callahan's Key
Callahan's Crosstime Saloon
In the fictional universe of Spider Robinson, Callahan's Place is a bar with strongly community-minded and empathic clientele. It appears in the Callahan's Crosstime Saloon stories In the fictional universe of Spider Robinson, Callahan's Place is a bar with strongly community-minded and empathic...

 focuses on the efforts of the group to prevent a vacuum metastability event caused by a high-energy point created through a combination of random factors.

The end of the universe has been used for satirical and comedic effect. In Douglas Adams
Douglas Adams
Douglas Noel Adams was an English writer and dramatist. He is best known as the author of The Hitchhiker's Guide to the Galaxy, which started life in 1978 as a BBC radio comedy before developing into a "trilogy" of five books that sold over 15 million copies in his lifetime, a television...

's science-fiction series The Hitchhiker's Guide to the Galaxy
The Hitchhiker's Guide to the Galaxy
The Hitchhiker's Guide to the Galaxy is a science fiction comedy series created by Douglas Adams. Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, and over several years it gradually became an international multi-media phenomenon...

, the "Restaurant at the End of the Universe" and its patrons are projected through time to the end of the universe, for guests to watch the event as dinner entertainment. Zaphod Beeblebrox
Zaphod Beeblebrox
Zaphod Beeblebrox is a fictional character in the various versions of the humorous science fiction story The Hitchhiker's Guide to the Galaxy by Douglas Adams who based him on his Cambridge contemporary, Johnny Simpson....

, the three-armed, two-headed former President of the Galaxy, scorned the main event, describing it as nothing but a "gnaB giB", or the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 in reverse. The astronomical cost of this exercise is paid for by depositing a small sum in the restaurant's account when the booking is made—by the end of the universe this has become a huge fortune due to the operation of compound interest.

The concept of an end to the universe has inspired some authors to explore the more human-centric topics of fate
Destiny
Destiny or fate refers to a predetermined course of events. It may be conceived as a predetermined future, whether in general or of an individual...

 and free will
Free will
"To make my own decisions whether I am successful or not due to uncontrollable forces" -Troy MorrisonA pragmatic definition of free willFree will is the ability of agents to make choices free from certain kinds of constraints. The existence of free will and its exact nature and definition have long...

. In Kurt Vonnegut
Kurt Vonnegut
Kurt Vonnegut, Jr. was a 20th century American writer. His works such as Cat's Cradle , Slaughterhouse-Five and Breakfast of Champions blend satire, gallows humor and science fiction. He was known for his humanist beliefs and was honorary president of the American Humanist Association.-Early...

's classic novel Slaughterhouse Five, the primary character is a war veteran who is contacted by aliens from the planet Tralfamadore who claim that one of their scientists will accidentally destroy the universe while testing a new type of spaceship fuel. Tralfamadorians are aware of this event because they perceive all of time instantaneously, in a similar way to how someone would observe an entire range of mountains in one instant.

Though intended for comedic purposes, the Star Trek: Deep Space Nine
Star Trek: Deep Space Nine
Star Trek: Deep Space Nine is a science fiction television series set in the Star Trek universe...

episode "Chrysalis" features a trio of genetically-enhanced humans contemplating the end of the universe. They come to agree that the universe is far too massive, and that it will inevitably collapse in on itself; essentially, a Big Crunch. The quandary is depicted in the episode as evidence of the characters' eccentricities.

Bungie
Bungie
Bungie, Inc is an American video game developer currently located in Bellevue, Washington, USA. The company was established in May 1991 by University of Chicago undergraduate student Alex Seropian, who later brought in programmer Jason Jones after publishing Jones' game Minotaur: The Labyrinths of...

's video game, Marathon
Marathon (video game)
Marathon is a first-person shooter video game with a science fiction theme developed and published by Bungie released in December 1994 for the Apple Macintosh. The game was Bungie's second foray into the emerging genre of games with a first-person perspective, the first being Pathways into...

, has an AI who tries to escape the end of the universe. The end of Marathon Infinity
Marathon Infinity
Marathon Infinity is the third game in the Marathon Trilogy of science fiction first-person shooter computer games from Bungie Software. The game was released on October 15, 1996 and included more levels than its predecessor Marathon 2. These were larger, and formed part of a more intricate plot...

 takes place at the universe's final moments.

In the Futurama
Futurama
Futurama is an American animated science fiction sitcom created by Matt Groening and developed by Groening and David X. Cohen for the Fox Broadcasting Company. The series follows the adventures of a late 20th-century New York City pizza delivery boy, Philip J...

episode The Late Philip J. Fry
The Late Philip J. Fry
"The Late Philip J. Fry" is the seventh episode of the sixth season of the animated series Futurama. It originally aired on Comedy Central on July 29, 2010. In the episode, Fry attempts to make it on time to a birthday dinner date for Leela. He is sidetracked by Professor Farnsworth and Bender,...

, a time machine
Time Machine
A time machine is a fictional/hypothetical device used to achieve time travel. The term may also refer to:-Novels and films:* The Time Machine, an 1895 novel by H. G...

 is invented that can only travel into the future. An accident during the initial test hurdles Fry, Bender and Professor Farnsworth 10,000 years in the future. With no hope of getting back to their own time, the trio decide to kick back and watch the end of the universe together. Eventual Heat Death occurs, which leads to another Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 after which all time simply repeats itself indefinitely allowing the main characters to travel forward to their familiar location in the continuum and resume their lives unaffected. Even after making the same mistake again, Professor Farnsworth simply suggest that they "bring her around again". This 3rd universe is 10 feet lower than the old one however.

The setting for Greg Bear
Greg Bear
Gregory Dale Bear is an American science fiction and mainstream author. His work has covered themes of galactic conflict , artificial universes , consciousness and cultural practices , and accelerated evolution...

's City at the End of Time is one hundred trillion years in the future and explores the cold death of the universe.

In Stephen Baxter
Stephen Baxter
Stephen Baxter is a prolific British hard science fiction author. He has degrees in mathematics and engineering.- Writing style :...

's short story "Last Contact" describes a Big Rip.

Douglas Adams
Douglas Adams
Douglas Noel Adams was an English writer and dramatist. He is best known as the author of The Hitchhiker's Guide to the Galaxy, which started life in 1978 as a BBC radio comedy before developing into a "trilogy" of five books that sold over 15 million copies in his lifetime, a television...

 Humorously describes the end of the universe having turned into a major eating establishment in the second book in The Hitchhiker's Guide to the Galaxy
The Hitchhiker's Guide to the Galaxy
The Hitchhiker's Guide to the Galaxy is a science fiction comedy series created by Douglas Adams. Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, and over several years it gradually became an international multi-media phenomenon...

, The Restaurant at the End of the Universe
The Restaurant at the End of the Universe
The Restaurant at the End of the Universe is the second book in the Hitchhiker's Guide to the Galaxy comedy science fiction trilogy of five by Douglas Adams. It was originally published by Pan Books as a paperback. The book was inspired by the song "Grand Hotel" by British rock band Procol Harum...


See also



  • Anthropic principle
    Anthropic principle
    In astrophysics and cosmology, the anthropic principle is the philosophical argument that observations of the physical Universe must be compatible with the conscious life that observes it. Some proponents of the argument reason that it explains why the Universe has the age and the fundamental...

  • Arrow of time
    Arrow of time
    The arrow of time, or time’s arrow, is a term coined in 1927 by the British astronomer Arthur Eddington to describe the "one-way direction" or "asymmetry" of time...

  • Big Bang
    Big Bang
    The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

  • Big Crunch
    Big Crunch
    In physical cosmology, the Big Crunch is one possible scenario for the ultimate fate of the universe, in which the metric expansion of space eventually reverses and the universe recollapses, ultimately ending as a black hole singularity.- Overview :...

  • Big Freeze
  • Big Rip
    Big Rip
    The Big Rip is a cosmological hypothesis first published in 2003, about the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, is progressively torn apart by the expansion of the universe at a certain time in the future...

  • Big Bounce
    Big Bounce
    The Big Bounce is a theoretical scientific model of the formation of the known universe. It is implied by 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.- Expansion and contraction...

  • Cosmology
    Cosmology
    Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

  • Cyclic model
    Cyclic model
    A cyclic model is any of several cosmological models in which the universe follows infinite, 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...

  • Doomsday event
    Doomsday event
    A doomsday event is a specific, plausibly verifiable or hypothetical occurrence which has an exceptionally destructive effect on the human race...

  • Dyson's eternal intelligence
    Dyson's eternal intelligence
    Dyson's eternal intelligence is a concept that states an intelligent being would be able to think an infinite number of thoughts in an open universe....

  • Eschatology
    Eschatology
    Eschatology is a part of theology, philosophy, and futurology concerned with what are believed to be the final events in history, or the ultimate destiny of humanity, commonly referred to as the end of the world or the World to Come...

  • Esoteric cosmology
    Esoteric cosmology
    Esoteric cosmology is cosmology that is an intrinsic part of an esoteric or occult system of thought. It almost always deals with at least some of the following themes: emanation, involution, spiritual evolution, epigenesis, planes of existence or higher worlds , hierarchies of spiritual beings,...

  • False vacuum
    False vacuum
    In quantum field theory, a false vacuum is a metastable sector of space that appears to be a perturbative vacuum, but is unstable due to instanton effects that may tunnel to a lower energy state. This tunneling can be caused by quantum fluctuations or the creation of high-energy particles...

  • Final anthropic principle
  • General relativity
    General relativity
    General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

  • Heat death of the universe
    Heat death of the universe
    The heat death of the universe is a suggested ultimate fate of the universe, in which the universe has diminished to a state of no thermodynamic free energy and therefore can no longer sustain motion or life. Heat death does not imply any particular absolute temperature; it only requires that...

  • Kardashev scale
    Kardashev scale
    The Kardashev scale is a method of measuring an advanced civilization's level of technological advancement. The scale is only theoretical and in terms of an actual civilization highly speculative; however, it puts energy consumption of an entire civilization in a cosmic perspective. It was first...

  • Multiverse
    Multiverse (science)
    The multiverse is the hypothetical set of multiple possible universes that together comprise everything that exists and can exist: the entirety of space, time, matter, and energy as well as the physical laws and constants that describe them...

  • Frank J. Tipler#The Omega Point
  • Shape of the universe
    Shape of the Universe
    The shape of the universe is a matter of debate in physical cosmology over the local and global geometry of the universe which considers both curvature and topology, though, strictly speaking, it goes beyond both...

  • Space and survival
    Space and survival
    Space and survival is the relationship between outer space and the long-term survival of the human species and civilization. Its investigation is justified by the fact that space colonization and space science could prevent many human extinction scenarios...

  • Timeline of cosmology
    Timeline of cosmology
    This timeline of cosmological theories and discoveries is a chronological record of the development of humanity's understanding of the cosmos over the last two-plus millennia. Modern cosmological ideas follow the development of the scientific discipline of physical cosmology.-Pre-1900:* ca...

  • Timeline of the Big Bang
    Timeline of the Big Bang
    This timeline of the Big Bang describes the history of the universe according to the prevailing scientific theory of how the universe came into being, using the cosmological time parameter of comoving coordinates...

  • Zero-energy Universe
    Zero-energy Universe
    The zero-energy universe hypothesis states that the total amount of energy in the universe is exactly zero. When the energy of the universe is considered from a pseudo-tensor point of view, zero values are obtained in the resulting calculations...


Scientists:
  • John D. Barrow
    John D. Barrow
    -External links:****** The Forum-Publications available on the Internet:************...

  • Freeman Dyson
    Freeman Dyson
    Freeman John Dyson FRS is a British-born American theoretical physicist and mathematician, famous for his work in quantum field theory, solid-state physics, astronomy and nuclear engineering. Dyson is a member of the Board of Sponsors of the Bulletin of the Atomic Scientists...

  • Alan Guth
    Alan Guth
    Alan Harvey Guth is an American theoretical physicist and cosmologist. Guth has researched elementary particle theory...

  • Andrei Linde
    Andrei Linde
    Andrei Dmitriyevich Linde is a Russian-American theoretical physicist and professor of Physics at Stanford University. Dr. Linde is best known for his work on the concept of the inflationary universe. He received his Bachelor of Science degree from Moscow State University. In 1975, Linde was...

  • Frank J. Tipler
    Frank J. Tipler
    Frank Jennings Tipler is a mathematical physicist and cosmologist, holding a joint appointment in the Departments of Mathematics and Physics at Tulane University. Tipler has authored books and papers on the Omega Point, which he claims is a mechanism for the resurrection of the dead. It has been...



Nonfiction


Fiction

  • Anderson, Poul
    Poul Anderson
    Poul William Anderson was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century. Anderson also authored several works of fantasy, historical novels, and a prodigious number of short stories...

    . Tau Zero.
  • Asimov, Isaac
    Isaac Asimov
    Isaac Asimov was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular science books. Asimov was one of the most prolific writers of all time, having written or edited more than 500 books and an estimated 90,000...

    . The Last Question
    The Last Question
    "The Last Question" is a science fiction short story by Isaac Asimov. It first appeared in the November 1956 issue of Science Fiction Quarterly and was reprinted in the collections Nine Tomorrows , The Best of Isaac Asimov , Robot Dreams , the retrospective Opus 100 , and in Isaac Asimov: The...

    .
  • Barrow, John
    John D. Barrow
    -External links:****** The Forum-Publications available on the Internet:************...

    . Impossibility.
  • Baxter, Stephen
    Stephen Baxter
    Stephen Baxter is a prolific British hard science fiction author. He has degrees in mathematics and engineering.- Writing style :...

    . Vacuum Diagrams, Deep Future, Manifold: Time, Exultant, and others.
  • Modesitt, L. E., Jr.
    L. E. Modesitt, Jr.
    L. E. Modesitt, Jr. is an author of 56 science fiction and fantasy novels. He is best known for the fantasy series The Saga of Recluce....

     Gravity Dreams
    Gravity Dreams
    Gravity Dreams is a 2000 science fiction novel by L. E. Modesitt, Jr.-Synopsis:Set in the distant future of the year 4512, wherein humans have achieved spaceflight faster than the speed of light, along with nanotechnology, Gravity Dreams centers itself around its main character, Tyndel...

    .

External links