document_title: Electromagnetism

question_text: who discovered the link between electricity and magnetism

text: Electromagnetism

text: History of the theory[edit]

text: Originally, electricity and magnetism were considered to be two separate forces. This view changed, however, with the publication of James Clerk Maxwell's 1873 A Treatise on Electricity and Magnetism in which the interactions of positive and negative charges were shown to be mediated by one force. There are four main effects resulting from these interactions, all of which have been clearly demonstrated by experiments:

text:
Electric charges attract or repel one another with a force inversely proportional to the square of the distance between them: unlike charges attract, like ones repel.
Magnetic poles (or states of polarization at individual points) attract or repel one another in a manner similar to positive and negative charges and always exist as pairs: every north pole is yoked to a south pole.
An electric current inside a wire creates a corresponding circumferential magnetic field outside the wire. Its direction (clockwise or counter-clockwise) depends on the direction of the current in the wire.
A current is induced in a loop of wire when it is moved toward or away from a magnetic field, or a magnet is moved towards or away from it; the direction of current depends on that of the movement.

tag: ol

text: While preparing for an evening lecture on 21 April 1820, Hans Christian Ørsted made a surprising observation. As he was setting up his materials, he noticed a compass needle deflected away from magnetic north when the electric current from the battery he was using was switched on and off. This deflection convinced him that magnetic fields radiate from all sides of a wire carrying an electric current, just as light and heat do, and that it confirmed a direct relationship between electricity and magnetism.

text: At the time of discovery, Ørsted did not suggest any satisfactory explanation of the phenomenon, nor did he try to represent the phenomenon in a mathematical framework. However, three months later he began more intensive investigations. Soon thereafter he published his findings, proving that an electric current produces a magnetic field as it flows through a wire. The CGS unit of magnetic induction (oersted) is named in honor of his contributions to the field of electromagnetism.

text: His findings resulted in intensive research throughout the scientific community in electrodynamics. They influenced French physicist André-Marie Ampère's developments of a single mathematical form to represent the magnetic forces between current-carrying conductors. Ørsted's discovery also represented a major step toward a unified concept of energy.

text: This unification, which was observed by Michael Faraday, extended by James Clerk Maxwell, and partially reformulated by Oliver Heaviside and Heinrich Hertz, is one of the key accomplishments of 19th century mathematical physics. It has had far-reaching consequences, one of which was the understanding of the nature of light. Unlike what was proposed by electromagnetic theory of that time, light and other electromagnetic waves are at present seen as taking the form of quantized, self-propagating oscillatory electromagnetic field disturbances called photons. Different frequencies of oscillation give rise to the different forms of electromagnetic radiation, from radio waves at the lowest frequencies, to visible light at intermediate frequencies, to gamma rays at the highest frequencies.

text: Ørsted was not the only person to examine the relationship between electricity and magnetism. In 1802, Gian Domenico Romagnosi, an Italian legal scholar, deflected a magnetic needle using a Voltaic pile. The factual setup of the experiment is not completely clear, so if current flew across the needle or not. An account of the discovery was published in 1802 in an Italian newspaper, but it was largely overlooked by the contemporary scientific community, because Romagnosi seemingly did not belong to this community.[4]

text: Fundamental forces[edit]

text: The electromagnetic force is one of the four known fundamental forces. The other fundamental forces are:

text:
the weak nuclear force, which binds to all known particles in the Standard Model, and causes certain forms of radioactive decay. (In particle physics though, the electroweak interaction is the unified description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction);
the strong nuclear force, which binds quarks to form nucleons, and binds nucleons to form nuclei
the gravitational force.

text: All other forces (e.g., friction, contact forces) are derived from these four fundamental forces (including momentum which is carried by the movement of particles).

text: The electromagnetic force is the one responsible for practically all the phenomena one encounters in daily life above the nuclear scale, with the exception of gravity. Roughly speaking, all the forces involved in interactions between atoms can be explained by the electromagnetic force acting between the electrically charged atomic nuclei and electrons of the atoms. Electromagnetic forces also explain how these particles carry momentum by their movement. This includes the forces we experience in "pushing" or "pulling" ordinary material objects, which result from the intermolecular forces that act between the individual molecules in our bodies and those in the objects. The electromagnetic force is also involved in all forms of chemical phenomena.

text: A necessary part of understanding the intra-atomic and intermolecular forces is the effective force generated by the momentum of the electrons' movement, such that as electrons move between interacting atoms they carry momentum with them. As a collection of electrons becomes more confined, their minimum momentum necessarily increases due to the Pauli exclusion principle. The behaviour of matter at the molecular scale including its density is determined by the balance between the electromagnetic force and the force generated by the exchange of momentum carried by the electrons themselves.

text: Classical electrodynamics[edit]

text: In 1600, William Gilbert proposed, in his De Magnete, that electricity and magnetism, while both capable of causing attraction and repulsion of objects, were distinct effects. Mariners had noticed that lightning strikes had the ability to disturb a compass needle. The link between lightning and electricity was not confirmed until Benjamin Franklin's proposed experiments in 1752. One of the first to discover and publish a link between man-made electric current and magnetism was Romagnosi, who in 1802 noticed that connecting a wire across a voltaic pile deflected a nearby compass needle. However, the effect did not become widely known until 1820, when Ørsted performed a similar experiment.[5] Ørsted's work influenced Ampère to produce a theory of electromagnetism that set the subject on a mathematical foundation.

text: A theory of electromagnetism, known as classical electromagnetism, was developed by various physicists the period between 1820 and 1873 when it culminated in the publication of a treatise by James Clerk Maxwell, which unified the preceding developments into a single theory and discovered the electromagnetic nature of light. In classical electromagnetism, the behavior of the electromagnetic field is described by a set of equations known as Maxwell's equations, and the electromagnetic force is given by the Lorentz force law.

text: One of the peculiarities of classical electromagnetism is that it is difficult to reconcile with classical mechanics, but it is compatible with special relativity. According to Maxwell's equations, the speed of light in a vacuum is a universal constant that is dependent only on the electrical permittivity and magnetic permeability of free space. This violates Galilean invariance, a long-standing cornerstone of classical mechanics. One way to reconcile the two theories (electromagnetism and classical mechanics) is to assume the existence of a luminiferous aether through which the light propagates. However, subsequent experimental efforts failed to detect the presence of the aether. After important contributions of Hendrik Lorentz and Henri Poincaré, in 1905, Albert Einstein solved the problem with the introduction of special relativity, which replaced classical kinematics with a new theory of kinematics compatible with classical electromagnetism. (For more information, see History of special relativity.)

text: In addition, relativity theory implies that in moving frames of reference a magnetic field transforms to a field with a nonzero electric component and conversely, a moving electric field transforms to a nonzero magnetic component, thus firmly showing that the phenomena are two sides of the same coin. Hence the term "electromagnetism". (For more information, see Classical electromagnetism and special relativity and Covariant formulation of classical electromagnetism.

text: Quantum mechanics[edit]

text:
Quantum field theory

Feynman diagram

History

Background[show]

Field theory
Electromagnetism
Weak force
Strong force
Quantum mechanics
Special relativity
General relativity
Gauge theory

Symmetries[show]

Symmetry in quantum mechanics
C-symmetry
P-symmetry
T-symmetry
Space translation symmetry
Time translation symmetry
Rotation symmetry
Lorentz symmetry
Poincaré symmetry
Gauge symmetry
Explicit symmetry breaking
Spontaneous symmetry breaking
Yang–Mills theory
Noether charge
Topological charge

Tools[show]

Anomaly
Crossing
Effective field theory
Expectation value
Faddeev–Popov ghosts
Feynman diagram
Lattice gauge theory
LSZ reduction formula
Partition function
Propagator
Quantization
Regularization
Renormalization
Vacuum state
Wick's theorem
Wightman axioms

Equations[show]

Dirac equation
Klein–Gordon equation
Proca equations
Wheeler–DeWitt equation
Bargmann–Wigner equations

Standard Model[show]

Quantum electrodynamics
Electroweak interaction
Quantum chromodynamics
Higgs mechanism

Incomplete theories[show]

Topological quantum field theory
String theory
Supersymmetry
Technicolor
Theory of everything
Quantum gravity

Scientists[show]

C. D. Anderson
P. W. Anderson
Bethe
Bjorken
Bogoliubov
Brout
Callan
Coleman
DeWitt
Dirac
Dyson
Englert
Fermi
Feynman
Fierz
Fock
Fröhlich
Glashow
Gell-Mann
Gross
Guralnik
Heisenberg
Higgs
Haag
Hagen
't Hooft
Jordan
Kendall
Kibble
Lamb
Landau
Lee
Majorana
Mills
Nambu
Nishijima
Parisi
Polyakov
Salam
Schwinger
Skyrme
Sudarshan
Tomonaga
Veltman
Ward
Weinberg
Weisskopf
Weyl
Wilczek
Wilson
Yang
Yukawa

v
t
e

text: Early quantum theory[edit]

text: In a second paper published in 1905, Albert Einstein undermined the very foundations of classical electromagnetism. In his theory of the photoelectric effect, for which he won the Nobel prize in physics, he posited that light could exist in discrete particle-like quantities, which later came to be called photons. Einstein's theory of the photoelectric effect extended the insights that appeared in the solution of the ultraviolet catastrophe presented by Max Planck in 1900 and who coined the term "quanta" . In his work, Planck showed that hot objects emit electromagnetic radiation in discrete packets ("quanta"), which leads to a finite total energy emitted as black body radiation. Both of these results were in direct contradiction with the classical view of light as a continuous wave. Planck's and Einstein's theories were progenitors of quantum mechanics, which, when formulated in 1925, necessitated the invention of a quantum theory of electromagnetism.

text: Quantum electrodynamics[edit]

text: Maxwell's equations have been superseded by quantum electrodynamics (QED). Richard Feynman called it "the jewel of physics"[6]:Ch1 for its extremely accurate predictions of quantities like the Lamb shift,[7] and measurement of the magnetic moment of the electron.[8] The electromagnetic field is quantized by imagining that at every point in space and time is a quantum harmonic oscillator. The empty field (vacuum state) fluctuates randomly as a consequence of the uncertainty principle. This theory, completed in the 1940s–1950s, is one of the most accurate theories known to physics in situations where perturbation theory can be applied. Like classical electromagnetism, QED is a linear U(1) gauge group.

text: Electroweak interaction[edit]

text: The electroweak interaction is a unified field theory description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction. It is a SU(2) × U(1) gauge group. Although these two forces appear very different at everyday low energies, the theory models them as two different aspects of the same force. At energies greater than 100 GeV, called the unification energy, the two forces merge into a single electroweak force. Thus when the universe was hot enough (approximately 1015 K, a temperature that was exceeded until shortly after the Big Bang) the electromagnetic force and weak force were merged into the electroweak force. With the cooling of the universe, at the end of the electroweak epoch, the electroweak force separated into the electromagnetic force and the weak force. During the following quark epoch, it was still too hot for quarks to combine into hadrons and they moved about freely.

text: Chaotic and emergent phenomena[edit]

text:
Beyond the Standard Model

Simulated Large Hadron Collider CMS particle detector data depicting a Higgs boson produced by colliding protons decaying into hadron jets and electrons

Standard Model

Evidence[show]

Hierarchy problem
Dark matter
Cosmological constant problem
Strong CP problem
Neutrino oscillation

Theories[show]

Technicolor
Kaluza–Klein theory
Grand Unified Theory
Theory of everything
String theory
Causal fermion systems
Superfluid vacuum theory

Supersymmetry[show]

MSSM
Superstring theory
Supergravity

Quantum gravity[show]

String theory
Loop quantum gravity
Causal dynamical triangulation
Causal fermion systems
Causal sets
Canonical quantum gravity
Superfluid vacuum theory

Experiments[show]

ANNIE
Gran Sasso
INO
LHC
SNO
Super-K
Tevatron
NOνA

v
t
e

text: The mathematical models used in classical electromagnetism, quantum electrodynamics (QED) and the standard model all view the electromagnetic force as a linear set of equations. In these theories electromagnetism is a U(1) gauge theory, whose topological properties do not allow any complex nonlinear interaction of a field with and on itself.[9] For example, in the QED vacuum the field fluctuates randomly as a consequence of the uncertainty principle but these fluctuations cancel each other out with no overall observable effect. However, there are many observed nonlinear physical electromagnetic phenomena such as Aharonov–Bohm (AB)[10][11] and Altshuler–Aronov– Spivak (AAS) effects,[12] Berry,[13] Aharonov– Anandan,[14] Pancharatnam[15] and Chiao–Wu[16] phase rotation effects, Josephson effect,[17] [18] Quantum Hall effect,[19] the de Haas–van Alphen effect,[20] the Sagnac effect and many other physically observable phenomena which would indicate that the electromagnetic potential field has real physical meaning rather than being a mathematical artifact[21] and therefore an all encompassing theory would not confine electromagnetism as a local force as is currently done, but as a SU(2) gauge theory or higher geometry. Higher symmetries allow for nonlinear, aperiodic behaviour which manifest as a variety of complex non-equilibrium phenomena that do not arise in the linearised U(1) theory, such as multiple stable states, symmetry breaking, chaos and emergence.[22] In higher symmetry groups, the electromagnetic field is not a calm, randomly fluctuating, passive substance, but can at times can be viewed as a turbulent virtual plasma that can have complex vortices, entangled states and a rich nonlinear structure.

text: What are called Maxwell's equation's today are in fact a simplified version of the original equations reformulated by Heaviside, FitzGerald, Lodge and Hertz. The original equations used Hamilton's more expressive quaternion notation,[23] a kind of Clifford algebra, which fully subsumes the standard Maxwell vectorial equations largely used today.[24] In the late 1880s there was a debate over the relative merits of vector analysis and quaternions. According to Heaviside the electromagnetic potential field was purely metaphysical, an arbitrary mathematical fiction, that needed to be "murdered".[25] It was concluded that there was no need for the greater physical insights provided by the quaternions if the theory was purely local in nature. Local vector analysis has become the dominant way of using Maxwell's equations ever since. However, this strictly vectorial approach as led to a restrictive topological understanding in some areas of electromagnetism, for example, a full understanding of the energy transfer dynamics in Tesla's oscillator-shuttle-circuit can be achieved only in quaternionic algebra or higher SU(2) symmetries.[26] It has often been argued that quaternions are not compatible with special relativity,[27] but multiple papers have shown ways of incorporating relativity[28][29][30]

text: A good example of nonlinear electromagnetics is in high energy dense plasmas, where vortical phenomena occur which seemingly violate the second law of thermodynamics by increasing the energy gradient within the electromagnetic field and violate Maxwell's laws by creating ion currents which capture and concentrate their own and surrounding magnetic fields. In particular Lorentz force law, which elaborates Maxwell's equations is violated by these force free vortices.[31][32][33] These apparent violations are due to the fact that the traditional conservation laws in classical and quantum electrodynamics (QED) only display linear U(1) symmetry (in particular, by the extended Noether theorem,[34] conservation laws such as the laws of thermodynamics need not always apply to dissipative systems,[35][36] which are expressed in gauges of higher symmetry). The second law of thermodynamics states that in a closed linear system entropy flow can be only be positive (or exactly zero at the end of a cycle). However, negative entropy (i.e. increased order, structure or self-organisation) can spontaneously appear in an open nonlinear thermodynamic system that is far from equilibrium, so long as this emergent order accelerates the overall flow of entropy in the total system.

text:
Given the complex and adaptive behaviour that arises from nonlinear systems considerable attention in recent years has gone into studying a new class of phase transitions which occur at absolute zero temperature. These are quantum phase transitions which are driven by electromagnetic field fluctuations as a consequence of zero-point energy[37] A good example of a spontaneous phase transition that are attributed to zero-point fluctuations can be found in superconductors. Superconductivity is one of the best known empirically quantified macroscopic electromagnetic phenomena whose basis is recognised to be quantum mechanical in origin. The behaviour of the electric and magnetic fields under superconductivity is governed by the London equations. However, it has been questioned in a series of journal articles whether the quantum mechanically canonised London equations can be given a purely classical derivation.[38] Bostick[39][40] for instance, has claimed to show that the London equations do indeed have a classical origin that applies to superconductors and to some collisionless plasmas as well. In particular it has been asserted that the Beltrami vortices in the plasma focus display the same paired flux-tube morphology as Type II superconductors.[41][42] Others have also pointed out this connection, Fröhlich[43] has shown that the hydrodynamic equations of compressible fluids, together with the London equations, lead to a macroscopic parameter (

μ

{\displaystyle \mu }

 = electric charge density / mass density), without involving either quantum phase factors or Planck's constant. In essence, it has been asserted that Beltrami plasma vortex structures are able to at least simulate the morphology of Type I and Type II superconductors. This occurs because the "organised" dissipative energy of the vortex configuration comprising the ions and electrons far exceeds the "disorganised" dissipative random thermal energy. The transition from disorganised fluctuations to organised helical structures is a phase transition involving a change in the condensate's energy (i.e. the ground state or zero-point energy) but without any associated rise in temperature.[44] This is an example of zero-point energy having multiple stable states (see Quantum phase transition, Quantum critical point, Topological degeneracy, Topological order[45]) and where the overall system structure is independent of a reductionist or deterministic view, that "classical" macroscopic order can also causally affect quantum phenomena.

text: Quantities and units[edit]

text: Electromagnetic units are part of a system of electrical units based primarily upon the magnetic properties of electric currents, the fundamental SI unit being the ampere. The units are:

text:
ampere (electric current)
coulomb (electric charge)
farad (capacitance)
henry (inductance)
ohm (resistance)
siemens (conductance)
tesla (magnetic flux density)
volt (electric potential)
watt (power)
weber (magnetic flux)

text: In the electromagnetic cgs system, electric current is a fundamental quantity defined via Ampère's law and takes the permeability as a dimensionless quantity (relative permeability) whose value in a vacuum is unity. As a consequence, the square of the speed of light appears explicitly in some of the equations interrelating quantities in this system.

text:
SI electromagnetism units

Symbol[46]
Name of Quantity
Derived Units
Unit
Base Units

I
electric current
ampere (SI base unit)
A
A (= W/V = C/s)

Q
electric charge
coulomb
C
A⋅s

U, ΔV, Δφ; E
potential difference; electromotive force
volt
V
kg⋅m2⋅s−3⋅A−1 (= J/C)

R; Z; X
electric resistance; impedance; reactance
ohm
Ω
kg⋅m2⋅s−3⋅A−2 (= V/A)

ρ
resistivity
ohm metre
Ω⋅m
kg⋅m3⋅s−3⋅A−2

P
electric power
watt
W
kg⋅m2⋅s−3 (= V⋅A)

C
capacitance
farad
F
kg−1⋅m−2⋅s4⋅A2 (= C/V)

E
electric field strength
volt per metre
V/m
kg⋅m⋅s−3⋅A−1 (= N/C)

D
electric displacement field
coulomb per square metre
C/m2
A⋅s⋅m−2

ε
permittivity
farad per metre
F/m
kg−1⋅m−3⋅s4⋅A2

χe
electric susceptibility
(dimensionless)
–
–

G; Y; B
conductance; admittance; susceptance
siemens
S
kg−1⋅m−2⋅s3⋅A2 (= Ω−1)

κ, γ, σ
conductivity
siemens per metre
S/m
kg−1⋅m−3⋅s3⋅A2

B
magnetic flux density, magnetic induction
tesla
T
kg⋅s−2⋅A−1 (= Wb/m2 = N⋅A−1⋅m−1)

Φ

{\displaystyle \Phi }

magnetic flux
weber
Wb
kg⋅m2⋅s−2⋅A−1 (= V⋅s)

H
magnetic field strength
ampere per metre
A/m
A⋅m−1

L, M
inductance
henry
H
kg⋅m2⋅s−2⋅A−2 (= Wb/A = V⋅s/A)

μ
permeability
henry per metre
H/m
kg⋅m⋅s−2⋅A−2

χ
magnetic susceptibility
(dimensionless)
–
–

J
current density
ampere per square metre
A/m2
C⋅m−2⋅s−1

text: Formulas for physical laws of electromagnetism (such as Maxwell's equations) need to be adjusted depending on what system of units one uses. This is because there is no one-to-one correspondence between electromagnetic units in SI and those in CGS, as is the case for mechanical units. Furthermore, within CGS, there are several plausible choices of electromagnetic units, leading to different unit "sub-systems", including Gaussian, "ESU", "EMU", and Heaviside–Lorentz. Among these choices, Gaussian units are the most common today, and in fact the phrase "CGS units" is often used to refer specifically to CGS-Gaussian units.


document_title: Merlin (miniseries)

question_text: who does helena bonham carter play in merlin

root

text: Merlin (miniseries)

text: Plot[edit]

text: This article's plot summary may be too long or excessively detailed. Please help improve it by removing unnecessary details and making it more concise. (March 2015) (Learn how and when to remove this template message)

tag: table

text: Merlin, now an elderly man, tells his story, explaining how Britain was faced with rulers and invasion that are increasingly destructive to its own people. Queen Mab (Miranda Richardson), goddess of the fey, seeks to reclaim her power by drawing people back to the "Old Ways". To do so, she creates a wizard named Merlin, whom she intends to champion her crusade. After Merlin's mother dies giving birth to him, his guardian Ambrosia (Billie Whitelaw), tells Mab she is too cruel and cold to raise Merlin (Daniel Brocklebank), and Mab reluctantly agrees that Ambrosia will bring him up until the time when Merlin's powers emerge, when Mab will send for him.

tag: p

text: Years later, a teenage Merlin recounts to Ambrosia how he has rescued a nobleman's daughter, Nimue (Isabella Rossellini), in the forests near their home by magically growing a small branch. A shocked Ambrosia tells him of his past and he is sent to Mab to begin his training with Frik (Martin Short), Mab's gnome servant; however, while able to learn magic, Merlin has little interest in helping Mab's crusade to restore the Old Ways, angering her. Merlin finds out from the Lady of the Lake (Miranda Richardson in a dual role), that her sister Mab let his birth mother die, and that Ambrosia is ill. Mab reaches Ambrosia's home before Merlin, but when Ambrosia refuses to convince Merlin to return to Mab, the fey queen lashes out in fury, fatally injuring Ambrosia inadvertantly. Ambrosia tells Merlin before she dies that he must follow his heart. Merlin tries to attack Mab, but can't defeat her; she dismisses the deaths of his mother and Ambrosia as "casualties of war" and vows that Merlin will help her in her quest for power. Merlin makes a blood-oath never to use magic in his effort to defeat Mab.

text: Many years pass. Merlin (now Sam Neill) is brought before the tyrant King Vortigern (Rutger Hauer) who is having problems constructing his castle, which keeps collapsing. Merlin calls the king stupid for believing what he has been told by a soothsayer (influenced by Mab) that the blood of a man with no mortal father will set the mortar. Merlin tells the king his vision: a red dragon representing Uther Pendragon, whose father, King Constant (John Gielgud) was murdered by Vortigern to seize his throne, defeats the white dragon that represents Vortigern. Mab misleads the king that he can vanquish Uther by sacrificing Nimue; Mab hopes doing so will cause Merlin to break his vow not to use magic. Merlin uses magic to save Nimue from the fire of the dragon and Nimue is sent to Avalon to recover from her burns. Merlin leaves Nimue to ask the Lady of the Lake for help against Vortigern; she gives him the magical sword Excalibur.

text: Merlin warns Uther of Vortigern's intention to attack him under the cover of winter; Uther heeds Merlin's warning and advice to confront the king on a frozen river. In the ensuing battle, Merlin duels Vortigern with Excalibur, using the sword's magic to open up the ice beneath Vortigern's feet, who plunges into the river and drowns. Merlin believes that Uther will be a decent king and gives to him Excalibur. Uther soon becomes obsessed with Igraine (Rachel De Thame), the wife of Gorlois, Lord of Cornwall. Merlin, worried about Uther misusing Excalibur, tricks Uther out of the sword and plunges it into the Rock of Ages (voice of James Earl Jones), who promises to keep it until a good man can withdraw it. Uther's mind is plagued by madness and lust, and Britain slides back into civil war. Merlin strikes a deal with Uther to bed Igraine, in exchange for guardianship of the son born from the union, and for the Duke and his men to be spared. Merlin transforms Uther's appearance into that of Gorlois. While Uther's forces lead Cornwall and his men away, Uther enters the castle and has sex with Igraine. Igraine's disfigured daughter, Morgan le Fay (Helena Bonham Carter), is the only one who sees through Uther's disguise. Uther betrays Merlin, going back on his word and having Cornwall and his men slaughtered. Merlin forever regrets allowing this to happen. While Igraine is in labor, at Mab's behest, Frik meets and amuses Morgan through his magic, offering to teach her the same in exchange for placing a black stone beneath the baby's sheets in his crib, cursing his life. Igraine then gives birth to King Arthur (Paul Curran), but at the cost of her own life. Mab then confronts Merlin, proclaiming Arthur to be damned, but Merlin vows to raise him in the ways of good, and hopes Arthur will help bring her down.

text: Arthur, who is unaware of his heritage, is tutored throughout his childhood by Merlin. He teaches him ethics and morals, hoping to make Arthur the image of goodness and a perfect King. Meanwhile, Uther commits suicide, which leaves the kingdom in turmoil over who will be the new King. Merlin informs Arthur of his rightful place as the only son of Uther and true heir to the throne. Mab attempts to kill Arthur by unleashing a pack of griffins; Merlin foils the attack by directing a swarm of bees to drive the monsters off, but is thus reminded that Mab is still a threat. The failed assassination likewise informs Mab that she is rapidly losing her power. With the throne vacant, all the noblemen in the kingdom try to take Excalibur from the Rock of Ages, but none can. Mab pleads with the rock to not let Arthur have the sword, saying he will bring bloodshed like his father, and will destroy the Old Ways. Arthur replies that he doesn't know what he will be, only what he is. This wise response makes the Rock of Ages see the goodness in Arthur, and grants him Excalibur.

text: Merlin presents Arthur to the gathered nobility vying for the throne; while most accept his claim upon seeing him bearing Excalibur, but a handful, led by Lord Lot (John Turner) initially refuse to accept Arthur as King. However, Arthur, using Merlin's teachings is able to convince Lot and his allies of his rightful claim to the throne. Satisfied that Arthur is the king destined to bring Britain stability, Merlin leaves, thinking the kingdom is finally at peace, but Mab comes up with a counter-plan of her own. She instructs Frik to seek out Arthur's half-sister Morgan (Helena Bonham Carter), and poison her mind by making her beautiful, and has her seduce Arthur, who is unaware of their relationship. Morgan and Arthur's act of incest eventually reaches Merlin, who races back to Camelot to confront Arthur. Merlin tells Arthur that Morgan will give birth to Arthur's abomination of a son, Mordred (Jason Done), whom Mab raises to become Arthur's downfall and bring back the Old Ways. Despite being from a cursed union, Mordred is exceptionally strong and grows at an abnormally fast rate. Arthur starts construction of his castle of Camelot and marries Guinevere (Lena Headey), while Merlin eventually forgives him for his indiscretion with Morgan. Unfortunately, when he tries to convince Morgan to stop plotting against Arthur, she disregards his warning, unaware that she and Mordred are merely pawns in Mab's ambition.

text: Arthur decides to take his knights on a quest for the Holy Grail, so he holds a tournament to crown a champion whom will be given the duty of defending and completing Camelot in his absence. Knowing that Arthur's enemies would take advantage of his absence, the Lady of the Lake vows to guide Merlin by boat to a "good man" worthy of being Camelot's guardian. Merlin eventually finds a boy, Galahad, by the riverbank in front of the estate of his parents, Lancelot - a skilled rider and swordsman - and Elaine of Astolat. Merlin brings Lancelot back to Camelot, where he then wins the tournament. Unfortunately, in Arthur's absence, Guinevere and Lancelot become infatuated with each other and embark on a love affair, despite Merlin warning of the consequences. Mab magically makes sure Lancelot's wife can see his betrayal, and she is found dead at the shores of Camelot not long after. Merlin accuses Lancelot of killing her through heartbreak and he flees Camelot in his guilt and shame. Arthur and his knights return to the city shortly afterwards, their quest a failure. Mordred then makes his presence as Arthur's son and heir known and reveals Guinevere's betrayal to all. Outmaneuvered by Mordred, Arthur is forced to condemn her to be burned at the stake for treason. Midway through the execution, Arthur changes his mind and begs Merlin to save her, so Merlin makes it rain, which saves Guinevere long enough for Lancelot to fight his way into Camelot and ride off with her to safety.

text: Mordred confronts Arthur, who denounces and banishes him. Mordred begins to raise an army among those dissatisfied with Arthur and Merlin. Meanwhile, Frik and Morgan have fallen in love after Mab's magic makes them both beautiful. When Morgan refuses to allow Mab to further use Mordred for her own ends, Mab kills her with Frik watching. Frik holds the dying Morgan and they revert to their true ugly forms, but they both call each other beautiful anyway, and she dies in his arms. When Frik vows revenge on Mab, she takes his powers away, and he later joins Arthur's army. Queen Mab then lures Nimue into a wilderness and removes the scars from her past injury, explaining she wishes to keep Merlin out of the way, so he cannot intervene in the battle to come. Wanting to be with him, Nimue agrees and sends for Merlin. He comes to her, but senses a trap when he realizes that the idyllic paradise they are in is a creation of Mab's. However, Nimue compels him to give up his war with her and simply be at peace. Meanwhile, the armies of Mordred and Arthur prepare themselves for the Battle of Camlann. Many on both sides are slain, and in a climactic duel, Arthur defeats Mordred. Mordred deals Arthur a fatal blow before Arthur kills him.

text: Knowing his protégé is dying, Merlin leaves Nimue to go to Arthur; however once he leaves, the magic of Mab's creation seals itself behind him, parting Merlin from Nimue forever. At the battlefield, both Mab and Merlin witness the deaths of their protégés. Mab's magic is unable to save Mordred while Arthur lives long enough to tell Merlin to return Excalibur to the place it was found so that no one else could wield its power. Arthur dies as Merlin gives back the sword to the Lady of the Lake. She is slowly dying as Old Ways are being rejected and forgotten. Merlin accuses her of lying to him about the guardian of Camelot, but she explains that, "it was the boy, Galahad," who was the true guardian and could have averted all this, though she assures Merlin that Arthur's death is not his fault. Merlin encounters Frik among the survivors of Arthur's army, who warns him that although Mab is greatly weakened, she is still dangerous.

text: Merlin confronts Mab at Camelot but the ensuing magical duel ends in stalemate. Mab sneers that she is invulnerable to conventional means of destruction, but Merlin responds that everyone ignoring her will led to her defeat. Mab slowly fades into nothing as Merlin, Frik and the entire court of Camelot turn their backs on her and walk away, ignoring her desperate screaming at them to acknowledge her. An aged Merlin is shown telling, in the same voice as the over voice narration at the beginning of the film, his story for coin. Frik makes himself known to Merlin with the caution that Merlin's version is not what Frik remembers. Merlin replies that his version he believes people will prefer. After Merlin finds his aged magic horse, Frik reveals it will lead him to Nimue. When Merlin asks how, Frik says that some time after Mab had disappeared, the spells she had cast has lost their effectiveness; Nimue was set free. After Merlin and Frik part ways, Merlin finds Nimue at Ambrosia's old forest home. Both lovers, now old, are transformed to younger days by Merlin's last act of magic, free at last to live out their lives together.

text: Cast[edit]

text:
Sam Neill as Merlin

Daniel Brocklebank as teenage Merlin

Miranda Richardson as Queen Mab and The Lady of The Lake
Isabella Rossellini as Nimue

Agnieszka Kozon as teenage Nimue

Martin Short as Frik
Paul Curran as Arthur
Helena Bonham Carter as Morgan le Fay

Alice Hamilton as young Morgan le Fay

Rutger Hauer as King Vortigern
James Earl Jones as the Rock of Ages
John Gielgud as King Constant
Billie Whitelaw as Ambrosia
Lena Headey as Guinevere
Jason Done as Mordred
Rachel De Thame as Igraine
Jeremy Sheffield as Lancelot
Sebastian Roché as Gawain
John McEnery as Lord Ardente
Roger Ashton-Griffiths as Sir Boris
Nicholas Clay as Lord Leo
Robert Addie as Sir Gilbert
Nickolas Grace as Sir Egbert
John Turner as Lord Lot
Peter Woodthorpe as Soothsayer

tag: ul

text: Production[edit]

text: It was produced by Dyson Lovell and directed by Steve Barron. The story is by Edward Khmara with the teleplay written by David Stevens and Peter Barnes.

text: Illustrator Alan Lee served as the film's conceptual designer. Despite heavy fantasy elements, the production is historically accurate to a degree, in keeping with the probable origins of the Arthurian legend in Sub-Roman Britain. The costumes and props used in the film include Dark Age or Early Medieval Celtic and Roman-style weapons (e.g. Iron Age swords) and armor (e.g. mail, scale and leather), while other Arthurian films like Excalibur, Knights of the Round Table and First Knight use High Medieval or Late Medieval-style weapons (e.g. longswords) and armour (e.g. full suits of plate). However, some anachronisms are present, like the use of the terms "knight" and "Sir" and the presence of the Roman lorica segmentata armour years after it was discontinued. During the conflict between Vortigern and Uther, Uther is said to be invading from Normandy, despite the film taking place long before the age of the Vikings, and thus of the Norman colonization which gave Normandy its name.

text: Nicholas Clay, who plays Guinevere's father Lord Leo, and Robert Addie, who plays Sir Gilbert, both appeared in John Boorman's 1981 film Excalibur, as (respectively) Lancelot and Mordred. Paul Curran, who played the adult King Arthur, played Kay alongside Jason Connery as Merlin in Merlin: The Quest Begins, an unrelated television film released the same year.

text: Accolades[edit]

text:
Award
Date of ceremony
Category
Recipient(s)
Result

Primetime Emmy Awards
September 13, 1998
Outstanding Limited Series
Merlin
Nominated

Outstanding Lead Actor in a Limited Series or Movie
Sam Neill
Nominated

Outstanding Supporting Actor in a Limited Series or Movie
Martin Short
Nominated

Outstanding Supporting Actress in a Limited Series or Movie
Helena Bonham Carter
Nominated

Outstanding Directing for a Limited Series, Movie, or Dramatic Special
Steve Barron
Nominated

Outstanding Writing for a Limited Series, Movie, or Dramatic Special
David Stevens, Peter Barnes and Edward Khmara
Nominated

Golden Globe Awards
January 24, 1999
Best Miniseries or Television Film
Merlin
Nominated

Best Actor – Miniseries or Television Film
Sam Neill
Nominated

Best Actress – Miniseries or Television Film
Miranda Richardson
Nominated

Best Supporting Actress – Series, Miniseries or Television Film
Helena Bonham Carter
Nominated

Satellite Awards
January 17, 1999
Best Supporting Actor – Series, Miniseries or Television Film
Martin Short
Nominated

text: Novelisations[edit]

text: Three books were written as novelisations of the film by James Mallory.[1] They included new ideas and characters including former priest Hearne and Lord Idath who rule Anoeth the land of Death and Winter. The books are as follows:

text: Much of what occurs in this book is not in the film, Merlin's mother Elissa is introduced as a Princess and novice Nun to Avalon who moves out with Ambrosia to Barnstable Forest when she becomes pregnant with Merlin. We further see Ambrosia's life and her failing faith in Queen Mab who gets Vortigern to take the throne of Britain from its Christian King Constance. Naturally some of the early events unfold such as the Lady of the Lake and Mab not agreeing on creating Merlin, etc. but we get to explore Merlin's magic education in the Lands of Magic under the hollow hill. An important element is Merlin being half magic and half human, where Fairy magic relies on illusion Merlin can make illusion real melding fairy spellcraft with human feeling merging the powers together in reality. Frik hides this and Merlin only uses it once in this book by shapeshifting into a bird. We meet Lord Idath the god of death and the wild hunt, Mab's former consort who does not fear as Mab does knowing there is life for him as long as mortals fear the shadow of midnight. The story ends just before Vortigern's men are on their way to get Merlin.

text: This is more familiar with the film where Merlin meets Vortigern and is given Excalibur by the Lady of the Lake. He and Nimue meet again and fall in love. Merlin becomes the King's Wizard and help Uther to become King only to be betrayed and manipulating events like Mab would by allowing him to sleep with the Duke of Cornwall's wife. Leading to the birth of Arthur and his tutoring as well as the building of Camelot and arrival of Lancelot. The book ends around this point with problems between the love triangle that is Arthur, Guinevere and Lancelot as well as the birth of Mordred.

text: The battle between Mab and Merlin continues and the disastrous love affair between Lancelot and Guinevere causes chaos. Mordred grows up and Morgan and Frik develop their relationship into true love. Naturally as the title suggests it leads to the end of magic but we learn of the thirteen treasures of Britain, one being Idath's horn which becomes more useful over time. Also Merlin uses his heart magic once more turning fairy illusion into reality and even becomes a wizard of pure thought.

text: Sequel[edit]

text: Hallmark Entertainment filmed a subsequent miniseries in Vancouver, entitled Merlin's Apprentice, with Neill and Richardson returning, though Richardson played a somewhat different role. The miniseries was broadcast in 2006 on Hallmark Channel.


document_title: Formation and evolution of the Solar System

question_text: where did the elements that formed planets come from

text: History[edit]

text: Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because it was not generally thought that the Solar System, in the sense we now understand it, existed. The first step toward a theory of Solar System formation and evolution was the general acceptance of heliocentrism, which placed the Sun at the centre of the system and the Earth in orbit around it. This concept had developed for millennia (Aristarchus of Samos had suggested it as early as 250 BC), but was not widely accepted until the end of the 17th century. The first recorded use of the term "Solar System" dates from 1704.[4]

text: The current standard theory for Solar System formation, the nebular hypothesis, has fallen into and out of favour since its formulation by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace in the 18th century. The most significant criticism of the hypothesis was its apparent inability to explain the Sun's relative lack of angular momentum when compared to the planets.[5] However, since the early 1980s studies of young stars have shown them to be surrounded by cool discs of dust and gas, exactly as the nebular hypothesis predicts, which has led to its re-acceptance.[6]

text: Understanding of how the Sun is expected to continue to evolve required an understanding of the source of its power. Arthur Stanley Eddington's confirmation of Albert Einstein's theory of relativity led to his realisation that the Sun's energy comes from nuclear fusion reactions in its core, fusing hydrogen into helium.[7] In 1935, Eddington went further and suggested that other elements also might form within stars.[8] Fred Hoyle elaborated on this premise by arguing that evolved stars called red giants created many elements heavier than hydrogen and helium in their cores. When a red giant finally casts off its outer layers, these elements would then be recycled to form other star systems.[8]

text: Formation[edit]

text: Pre-solar nebula[edit]

text: The nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud.[9] The cloud was about 20 parsec (65 light years) across,[9] while the fragments were roughly 1 parsec (three and a quarter light-years) across.[10] The further collapse of the fragments led to the formation of dense cores 0.01–0.1 pc (2,000–20,000 AU) in size.[note 1][9][11] One of these collapsing fragments (known as the pre-solar nebula) formed what became the Solar System.[12] The composition of this region with a mass just over that of the Sun (M☉) was about the same as that of the Sun today, with hydrogen, along with helium and trace amounts of lithium produced by Big Bang nucleosynthesis, forming about 98% of its mass. The remaining 2% of the mass consisted of heavier elements that were created by nucleosynthesis in earlier generations of stars.[13] Late in the life of these stars, they ejected heavier elements into the interstellar medium.[14]

text: The oldest inclusions found in meteorites, thought to trace the first solid material to form in the pre-solar nebula, are 4568.2 million years old, which is one definition of the age of the Solar System.[1] Studies of ancient meteorites reveal traces of stable daughter nuclei of short-lived isotopes, such as iron-60, that only form in exploding, short-lived stars. This indicates that one or more supernovae occurred near the Sun while it was forming. A shock wave from a supernova may have triggered the formation of the Sun by creating relatively dense regions within the cloud, causing these regions to collapse.[15] Because only massive, short-lived stars produce supernovae, the Sun must have formed in a large star-forming region that produced massive stars, possibly similar to the Orion Nebula.[16][17] Studies of the structure of the Kuiper belt and of anomalous materials within it suggest that the Sun formed within a cluster of between 1,000 and 10,000 stars with a diameter of between 6.5 and 19.5 light years and a collective mass of 3,000 M☉. This cluster began to break apart between 135 million and 535 million years after formation.[18][19] Several simulations of our young Sun interacting with close-passing stars over the first 100 million years of its life produce anomalous orbits observed in the outer Solar System, such as detached objects.[20]

text: Because of the conservation of angular momentum, the nebula spun faster as it collapsed. As the material within the nebula condensed, the atoms within it began to collide with increasing frequency, converting their kinetic energy into heat. The centre, where most of the mass collected, became increasingly hotter than the surrounding disc.[10] Over about 100,000 years,[9] the competing forces of gravity, gas pressure, magnetic fields, and rotation caused the contracting nebula to flatten into a spinning protoplanetary disc with a diameter of about 200 AU[10] and form a hot, dense protostar (a star in which hydrogen fusion has not yet begun) at the centre.[21]

text: At this point in its evolution, the Sun is thought to have been a T Tauri star.[22] Studies of T Tauri stars show that they are often accompanied by discs of pre-planetary matter with masses of 0.001–0.1 M☉.[23] These discs extend to several hundred AU—the Hubble Space Telescope has observed protoplanetary discs of up to 1000 AU in diameter in star-forming regions such as the Orion Nebula[24]—and are rather cool, reaching a surface temperature of only about 1000 kelvin at their hottest.[25] Within 50 million years, the temperature and pressure at the core of the Sun became so great that its hydrogen began to fuse, creating an internal source of energy that countered gravitational contraction until hydrostatic equilibrium was achieved.[26] This marked the Sun's entry into the prime phase of its life, known as the main sequence. Main-sequence stars derive energy from the fusion of hydrogen into helium in their cores. The Sun remains a main-sequence star today.[27]

text: Formation of the planets[edit]

text: The various planets are thought to have formed from the solar nebula, the disc-shaped cloud of gas and dust left over from the Sun's formation.[28] The currently accepted method by which the planets formed is accretion, in which the planets began as dust grains in orbit around the central protostar. Through direct contact, these grains formed into clumps up to 200 metres in diameter, which in turn collided to form larger bodies (planetesimals) of ~10 kilometres (km) in size.[29] These gradually increased through further collisions, growing at the rate of centimetres per year over the course of the next few million years.[29]

text: The inner Solar System, the region of the Solar System inside 4 AU, was too warm for volatile molecules like water and methane to condense, so the planetesimals that formed there could only form from compounds with high melting points, such as metals (like iron, nickel, and aluminium) and rocky silicates. These rocky bodies would become the terrestrial planets (Mercury, Venus, Earth, and Mars). These compounds are quite rare in the Universe, comprising only 0.6% of the mass of the nebula, so the terrestrial planets could not grow very large.[10] The terrestrial embryos grew to about 0.05 Earth masses (M⊕) and ceased accumulating matter about 100,000 years after the formation of the Sun; subsequent collisions and mergers between these planet-sized bodies allowed terrestrial planets to grow to their present sizes (see Terrestrial planets below).[30]

text: When the terrestrial planets were forming, they remained immersed in a disk of gas and dust. The gas was partially supported by pressure and so did not orbit the Sun as rapidly as the planets. The resulting drag and, more importantly, gravitational interactions with the surrounding material caused a transfer of angular momentum, and as a result the planets gradually migrated to new orbits. Models show that density and temperature variations in the disk governed this rate of migration,[31][32] but the net trend was for the inner planets to migrate inward as the disk dissipated, leaving the planets in their current orbits.[33]

text: The giant planets (Jupiter, Saturn, Uranus, and Neptune) formed further out, beyond the frost line, which is the point between the orbits of Mars and Jupiter where the material is cool enough for volatile icy compounds to remain solid. The ices that formed the Jovian planets were more abundant than the metals and silicates that formed the terrestrial planets, allowing the giant planets to grow massive enough to capture hydrogen and helium, the lightest and most abundant elements.[10] Planetesimals beyond the frost line accumulated up to 4 M⊕ within about 3 million years.[30] Today, the four giant planets comprise just under 99% of all the mass orbiting the Sun.[note 2] Theorists believe it is no accident that Jupiter lies just beyond the frost line. Because the frost line accumulated large amounts of water via evaporation from infalling icy material, it created a region of lower pressure that increased the speed of orbiting dust particles and halted their motion toward the Sun. In effect, the frost line acted as a barrier that caused material to accumulate rapidly at ~5 AU from the Sun. This excess material coalesced into a large embryo (or core) on the order of 10 M⊕, which began to accumulate an envelope via accretion of gas from the surrounding disc at an ever-increasing rate.[34][35] Once the envelope mass became about equal to the solid core mass, growth proceeded very rapidly, reaching about 150 Earth masses ~105 years thereafter and finally topping out at 318 M⊕.[36] Saturn may owe its substantially lower mass simply to having formed a few million years after Jupiter, when there was less gas available to consume.[30][37]

text: T Tauri stars like the young Sun have far stronger stellar winds than more stable, older stars. Uranus and Neptune are thought to have formed after Jupiter and Saturn did, when the strong solar wind had blown away much of the disc material. As a result, the planets accumulated little hydrogen and helium—not more than 1 M⊕ each. Uranus and Neptune are sometimes referred to as failed cores.[38] The main problem with formation theories for these planets is the timescale of their formation. At the current locations it would have taken millions of years for their cores to accrete.[37] This means that Uranus and Neptune may have formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated or were ejected outward (see Planetary migration below).[38][39] Motion in the planetesimal era was not all inward toward the Sun; the Stardust sample return from Comet Wild 2 has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt.[40]

text: After between three and ten million years,[30] the young Sun's solar wind would have cleared away all the gas and dust in the protoplanetary disc, blowing it into interstellar space, thus ending the growth of the planets.[41][42]

text: Subsequent evolution[edit]

text: The planets were originally thought to have formed in or near their current orbits. From that a minimum mass of the nebula i.e. the protoplanetary disc, was derived that was necessary to form the planets - the minimum mass solar nebula. It was derived that the nebula mass must have exceeded 3585 times that of the Earth.

text: However, this has been questioned during the last 20 years. Currently, many planetary scientists think that the Solar System might have looked very different after its initial formation: several objects at least as massive as Mercury were present in the inner Solar System, the outer Solar System was much more compact than it is now, and the Kuiper belt was much closer to the Sun.[43]

text: Terrestrial planets[edit]

text: At the end of the planetary formation epoch the inner Solar System was populated by 50–100 Moon- to Mars-sized planetary embryos.[44][45] Further growth was possible only because these bodies collided and merged, which took less than 100 million years. These objects would have gravitationally interacted with one another, tugging at each other's orbits until they collided, growing larger until the four terrestrial planets we know today took shape.[30] One such giant collision is thought to have formed the Moon (see Moons below), while another removed the outer envelope of the young Mercury.[46]

text: One unresolved issue with this model is that it cannot explain how the initial orbits of the proto-terrestrial planets, which would have needed to be highly eccentric to collide, produced the remarkably stable and nearly circular orbits they have today.[44] One hypothesis for this "eccentricity dumping" is that the terrestrials formed in a disc of gas still not expelled by the Sun. The "gravitational drag" of this residual gas would have eventually lowered the planets' energy, smoothing out their orbits.[45] However, such gas, if it existed, would have prevented the terrestrial planets' orbits from becoming so eccentric in the first place.[30] Another hypothesis is that gravitational drag occurred not between the planets and residual gas but between the planets and the remaining small bodies. As the large bodies moved through the crowd of smaller objects, the smaller objects, attracted by the larger planets' gravity, formed a region of higher density, a "gravitational wake", in the larger objects' path. As they did so, the increased gravity of the wake slowed the larger objects down into more regular orbits.[47]

text: Asteroid belt[edit]

text: The outer edge of the terrestrial region, between 2 and 4 AU from the Sun, is called the asteroid belt. The asteroid belt initially contained more than enough matter to form 2–3 Earth-like planets, and, indeed, a large number of planetesimals formed there. As with the terrestrials, planetesimals in this region later coalesced and formed 20–30 Moon- to Mars-sized planetary embryos;[48] however, the proximity of Jupiter meant that after this planet formed, 3 million years after the Sun, the region's history changed dramatically.[44] Orbital resonances with Jupiter and Saturn are particularly strong in the asteroid belt, and gravitational interactions with more massive embryos scattered many planetesimals into those resonances. Jupiter's gravity increased the velocity of objects within these resonances, causing them to shatter upon collision with other bodies, rather than accrete.[49]

text: As Jupiter migrated inward following its formation (see Planetary migration below), resonances would have swept across the asteroid belt, dynamically exciting the region's population and increasing their velocities relative to each other.[50] The cumulative action of the resonances and the embryos either scattered the planetesimals away from the asteroid belt or excited their orbital inclinations and eccentricities.[48][51] Some of those massive embryos too were ejected by Jupiter, while others may have migrated to the inner Solar System and played a role in the final accretion of the terrestrial planets.[48][52][53] During this primary depletion period, the effects of the giant planets and planetary embryos left the asteroid belt with a total mass equivalent to less than 1% that of the Earth, composed mainly of small planetesimals.[51] This is still 10–20 times more than the current mass in the main belt, which is now about 1/2,000 M⊕.[54] A secondary depletion period that brought the asteroid belt down close to its present mass is thought to have followed when Jupiter and Saturn entered a temporary 2:1 orbital resonance (see below).

text: The inner Solar System's period of giant impacts probably played a role in the Earth acquiring its current water content (~6×1021 kg) from the early asteroid belt. Water is too volatile to have been present at Earth's formation and must have been subsequently delivered from outer, colder parts of the Solar System.[55] The water was probably delivered by planetary embryos and small planetesimals thrown out of the asteroid belt by Jupiter.[52] A population of main-belt comets discovered in 2006 has been also suggested as a possible source for Earth's water.[55][56] In contrast, comets from the Kuiper belt or farther regions delivered not more than about 6% of Earth's water.[2][57] The panspermia hypothesis holds that life itself may have been deposited on Earth in this way, although this idea is not widely accepted.[58]

text: Planetary migration[edit]

text: According to the nebular hypothesis, the outer two planets may be in the "wrong place". Uranus and Neptune (known as the "ice giants") exist in a region where the reduced density of the solar nebula and longer orbital times render their formation highly implausible.[59] The two are instead thought to have formed in orbits near Jupiter and Saturn, where more material was available, and to have migrated outward to their current positions over hundreds of millions of years.[38]

text: The migration of the outer planets is also necessary to account for the existence and properties of the Solar System's outermost regions.[39] Beyond Neptune, the Solar System continues into the Kuiper belt, the scattered disc, and the Oort cloud, three sparse populations of small icy bodies thought to be the points of origin for most observed comets. At their distance from the Sun, accretion was too slow to allow planets to form before the solar nebula dispersed, and thus the initial disc lacked enough mass density to consolidate into a planet.[59] The Kuiper belt lies between 30 and 55 AU from the Sun, while the farther scattered disc extends to over 100 AU,[39] and the distant Oort cloud begins at about 50,000 AU.[60] Originally, however, the Kuiper belt was much denser and closer to the Sun, with an outer edge at approximately 30 AU. Its inner edge would have been just beyond the orbits of Uranus and Neptune, which were in turn far closer to the Sun when they formed (most likely in the range of 15–20 AU), and in 50% of simulations ended up opposite locations, with Uranus farther from the Sun than Neptune.[61][2][39]

text: According to the Nice model, after the formation of the Solar System, the orbits of all the giant planets continued to change slowly, influenced by their interaction with the large number of remaining planetesimals. After 500–600 million years (about 4 billion years ago) Jupiter and Saturn fell into a 2:1 resonance: Saturn orbited the Sun once for every two Jupiter orbits.[39] This resonance created a gravitational push against the outer planets, possibly causing Neptune to surge past Uranus and plough into the ancient Kuiper belt.[61] The planets scattered the majority of the small icy bodies inwards, while themselves moving outwards. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards.[39] This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward.[note 3] Those objects scattered by Jupiter into highly elliptical orbits formed the Oort cloud;[39] those objects scattered to a lesser degree by the migrating Neptune formed the current Kuiper belt and scattered disc.[39] This scenario explains the Kuiper belt's and scattered disc's present low mass. Some of the scattered objects, including Pluto, became gravitationally tied to Neptune's orbit, forcing them into mean-motion resonances.[62] Eventually, friction within the planetesimal disc made the orbits of Uranus and Neptune circular again.[39][63]

text: In contrast to the outer planets, the inner planets are not thought to have migrated significantly over the age of the Solar System, because their orbits have remained stable following the period of giant impacts.[30]

text: Another question is why Mars came out so small compared with Earth. A study by Southwest Research Institute, San Antonio, Texas, published June 6, 2011 (called the Grand Tack Hypothesis), proposes that Jupiter had migrated inward to 1.5 AU. After Saturn formed, migrated inward, and established the 2:3 mean motion resonance with Jupiter, the study assumes that both planets migrated back to their present positions. Jupiter thus would have consumed much of the material that would have created a bigger Mars. The same simulations also reproduce the characteristics of the modern asteroid belt, with dry asteroids and water-rich objects similar to comets.[64][65] However, it is unclear whether conditions in the solar nebula would have allowed Jupiter and Saturn to move back to their current positions, and according to current estimates this possibility appears unlikely.[66] Moreover, alternative explanations for the small mass of Mars exist.[67][68][69]

text: Late Heavy Bombardment and after[edit]

text: Gravitational disruption from the outer planets' migration would have sent large numbers of asteroids into the inner Solar System, severely depleting the original belt until it reached today's extremely low mass.[51] This event may have triggered the Late Heavy Bombardment that occurred approximately 4 billion years ago, 500–600 million years after the formation of the Solar System.[2][70] This period of heavy bombardment lasted several hundred million years and is evident in the cratering still visible on geologically dead bodies of the inner Solar System such as the Moon and Mercury.[2][71] The oldest known evidence for life on Earth dates to 3.8 billion years ago—almost immediately after the end of the Late Heavy Bombardment.[72]

text: Impacts are thought to be a regular (if currently infrequent) part of the evolution of the Solar System. That they continue to happen is evidenced by the collision of Comet Shoemaker–Levy 9 with Jupiter in 1994, the 2009 Jupiter impact event, the Tunguska event, the Chelyabinsk meteor and the impact feature Meteor Crater in Arizona. The process of accretion, therefore, is not complete, and may still pose a threat to life on Earth.[73][74]

text: Over the course of the Solar System's evolution, comets were ejected out of the inner Solar System by the gravity of the giant planets, and sent thousands of AU outward to form the Oort cloud, a spherical outer swarm of cometary nuclei at the farthest extent of the Sun's gravitational pull. Eventually, after about 800 million years, the gravitational disruption caused by galactic tides, passing stars and giant molecular clouds began to deplete the cloud, sending comets into the inner Solar System.[75] The evolution of the outer Solar System also appears to have been influenced by space weathering from the solar wind, micrometeorites, and the neutral components of the interstellar medium.[76]

text: The evolution of the asteroid belt after Late Heavy Bombardment was mainly governed by collisions.[77] Objects with large mass have enough gravity to retain any material ejected by a violent collision. In the asteroid belt this usually is not the case. As a result, many larger objects have been broken apart, and sometimes newer objects have been forged from the remnants in less violent collisions.[77] Moons around some asteroids currently can only be explained as consolidations of material flung away from the parent object without enough energy to entirely escape its gravity.[78]

text: Moons[edit]

text: Moons have come to exist around most planets and many other Solar System bodies. These natural satellites originated by one of three possible mechanisms:

text:
Co-formation from a circumplanetary disc (only in the cases of the giant planets);
Formation from impact debris (given a large enough impact at a shallow angle); and
Capture of a passing object.

text: Jupiter and Saturn have several large moons, such as Io, Europa, Ganymede and Titan, which may have originated from discs around each giant planet in much the same way that the planets formed from the disc around the Sun.[79][80][81] This origin is indicated by the large sizes of the moons and their proximity to the planet. These attributes are impossible to achieve via capture, while the gaseous nature of the primaries also make formation from collision debris unlikely. The outer moons of the giant planets tend to be small and have eccentric orbits with arbitrary inclinations. These are the characteristics expected of captured bodies.[82][83] Most such moons orbit in the direction opposite the rotation of their primary. The largest irregular moon is Neptune's moon Triton, which is thought to be a captured Kuiper belt object.[74]

text: Moons of solid Solar System bodies have been created by both collisions and capture. Mars's two small moons, Deimos and Phobos, are thought to be captured asteroids.[84] The Earth's Moon is thought to have formed as a result of a single, large head-on collision.[85][86] The impacting object probably had a mass comparable to that of Mars, and the impact probably occurred near the end of the period of giant impacts. The collision kicked into orbit some of the impactor's mantle, which then coalesced into the Moon.[85] The impact was probably the last in the series of mergers that formed the Earth. It has been further hypothesized that the Mars-sized object may have formed at one of the stable Earth–Sun Lagrangian points (either L4 or L5) and drifted from its position.[87] The moons of trans-Neptunian objects Pluto (Charon) and Orcus (Vanth) may also have formed by means of a large collision: the Pluto–Charon, Orcus–Vanth and Earth–Moon systems are unusual in the Solar System in that the satellite's mass is at least 1% that of the larger body.[88][89]

text: Future[edit]

text: Astronomers estimate that the Solar System as we know it today will not change drastically until the Sun has fused almost all the hydrogen fuel in its core into helium, beginning its evolution from the main sequence of the Hertzsprung–Russell diagram and into its red-giant phase. Even so, the Solar System will continue to evolve until then.

text: Long-term stability[edit]

text: The Solar System is chaotic over million- and billion-year timescales,[90] with the orbits of the planets open to long-term variations. One notable example of this chaos is the Neptune–Pluto system, which lies in a 3:2 orbital resonance. Although the resonance itself will remain stable, it becomes impossible to predict the position of Pluto with any degree of accuracy more than 10–20 million years (the Lyapunov time) into the future.[91] Another example is Earth's axial tilt, which, due to friction raised within Earth's mantle by tidal interactions with the Moon (see below), will be incomputable at some point between 1.5 and 4.5 billion years from now.[92]

text: The outer planets' orbits are chaotic over longer timescales, with a Lyapunov time in the range of 2–230 million years.[93] In all cases this means that the position of a planet along its orbit ultimately becomes impossible to predict with any certainty (so, for example, the timing of winter and summer become uncertain), but in some cases the orbits themselves may change dramatically. Such chaos manifests most strongly as changes in eccentricity, with some planets' orbits becoming significantly more—or less—elliptical.[94]

text: Ultimately, the Solar System is stable in that none of the planets are likely to collide with each other or be ejected from the system in the next few billion years.[93] Beyond this, within five billion years or so Mars's eccentricity may grow to around 0.2, such that it lies on an Earth-crossing orbit, leading to a potential collision. In the same timescale, Mercury's eccentricity may grow even further, and a close encounter with Venus could theoretically eject it from the Solar System altogether[90] or send it on a collision course with Venus or Earth.[95] This could happen within a billion years, according to numerical simulations in which Mercury's orbit is perturbed.[96]

text: Moon–ring systems[edit]

text: The evolution of moon systems is driven by tidal forces. A moon will raise a tidal bulge in the object it orbits (the primary) due to the differential gravitational force across diameter of the primary. If a moon is revolving in the same direction as the planet's rotation and the planet is rotating faster than the orbital period of the moon, the bulge will constantly be pulled ahead of the moon. In this situation, angular momentum is transferred from the rotation of the primary to the revolution of the satellite. The moon gains energy and gradually spirals outward, while the primary rotates more slowly over time.

text: The Earth and its Moon are one example of this configuration. Today, the Moon is tidally locked to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth. The Moon will continue to recede from Earth, and Earth's spin will continue to slow gradually. In about 50 billion years, if they survive the Sun's expansion, the Earth and Moon will become tidally locked to each other; each will be caught up in what is called a "spin–orbit resonance" in which the Moon will circle the Earth in about 47 days and both Moon and Earth will rotate around their axes in the same time, each only visible from one hemisphere of the other.[97][98] Other examples are the Galilean moons of Jupiter (as well as many of Jupiter's smaller moons)[99] and most of the larger moons of Saturn.[100]

text: A different scenario occurs when the moon is either revolving around the primary faster than the primary rotates, or is revolving in the direction opposite the planet's rotation. In these cases, the tidal bulge lags behind the moon in its orbit. In the former case, the direction of angular momentum transfer is reversed, so the rotation of the primary speeds up while the satellite's orbit shrinks. In the latter case, the angular momentum of the rotation and revolution have opposite signs, so transfer leads to decreases in the magnitude of each (that cancel each other out).[note 4] In both cases, tidal deceleration causes the moon to spiral in towards the primary until it either is torn apart by tidal stresses, potentially creating a planetary ring system, or crashes into the planet's surface or atmosphere. Such a fate awaits the moons Phobos of Mars (within 30 to 50 million years),[101] Triton of Neptune (in 3.6 billion years),[102] Metis and Adrastea of Jupiter,[103] and at least 16 small satellites of Uranus and Neptune. Uranus's Desdemona may even collide with one of its neighboring moons.[104]

text: A third possibility is where the primary and moon are tidally locked to each other. In that case, the tidal bulge stays directly under the moon, there is no transfer of angular momentum, and the orbital period will not change. Pluto and Charon are an example of this type of configuration.[105]

text: Prior to the 2004 arrival of the Cassini–Huygens spacecraft, the rings of Saturn were widely thought to be much younger than the Solar System and were not expected to survive beyond another 300 million years. Gravitational interactions with Saturn's moons were expected to gradually sweep the rings' outer edge toward the planet, with abrasion by meteorites and Saturn's gravity eventually taking the rest, leaving Saturn unadorned.[106] However, data from the Cassini mission led scientists to revise that early view. Observations revealed 10 km-wide icy clumps of material that repeatedly break apart and reform, keeping the rings fresh. Saturn's rings are far more massive than the rings of the other giant planets. This large mass is thought to have preserved Saturn's rings since it first formed 4.5 billion years ago, and is likely to preserve them for billions of years to come.[107]

text: The Sun and planetary environments[edit]

text: In the long term, the greatest changes in the Solar System will come from changes in the Sun itself as it ages. As the Sun burns through its supply of hydrogen fuel, it gets hotter and burns the remaining fuel even faster. As a result, the Sun is growing brighter at a rate of ten percent every 1.1 billion years.[108] In one billion years' time, as the Sun's radiation output increases, its circumstellar habitable zone will move outwards, making the Earth's surface too hot for liquid water to exist there naturally. At this point, all life on land will become extinct.[109] Evaporation of water, a potent greenhouse gas, from the oceans' surface could accelerate temperature increase, potentially ending all life on Earth even sooner.[110] During this time, it is possible that as Mars's surface temperature gradually rises, carbon dioxide and water currently frozen under the surface regolith will release into the atmosphere, creating a greenhouse effect that will heat the planet until it achieves conditions parallel to Earth today, providing a potential future abode for life.[111] By 3.5 billion years from now, Earth's surface conditions will be similar to those of Venus today.[108]

text: Around 5.4 billion years from now, the core of the Sun will become hot enough to trigger hydrogen fusion in its surrounding shell.[109] This will cause the outer layers of the star to expand greatly, and the star will enter a phase of its life in which it is called a red giant.[112][113] Within 7.5 billion years, the Sun will have expanded to a radius of 1.2 AU—256 times its current size. At the tip of the red giant branch, as a result of the vastly increased surface area, the Sun's surface will be much cooler (about 2600 K) than now and its luminosity much higher—up to 2,700 current solar luminosities. For part of its red giant life, the Sun will have a strong stellar wind that will carry away around 33% of its mass.[109][114][115] During these times, it is possible that Saturn's moon Titan could achieve surface temperatures necessary to support life.[116][117]

text: As the Sun expands, it will swallow the planets Mercury and Venus.[118] Earth's fate is less clear; although the Sun will envelop Earth's current orbit, the star's loss of mass (and thus weaker gravity) will cause the planets' orbits to move farther out.[109] If it were only for this, Venus and Earth would probably escape incineration,[114] but a 2008 study suggests that Earth will likely be swallowed up as a result of tidal interactions with the Sun's weakly bound outer envelope.[109]

text: Gradually, the hydrogen burning in the shell around the solar core will increase the mass of the core until it reaches about 45% of the present solar mass. At this point the density and temperature will become so high that the fusion of helium into carbon will begin, leading to a helium flash; the Sun will shrink from around 250 to 11 times its present (main-sequence) radius. Consequently, its luminosity will decrease from around 3,000 to 54 times its current level, and its surface temperature will increase to about 4770 K. The Sun will become a horizontal giant, burning helium in its core in a stable fashion much like it burns hydrogen today. The helium-fusing stage will last only 100 million years. Eventually, it will have to again resort to the reserves of hydrogen and helium in its outer layers and will expand a second time, turning into what is known as an asymptotic giant. Here the luminosity of the Sun will increase again, reaching about 2,090 present luminosities, and it will cool to about 3500 K.[109] This phase lasts about 30 million years, after which, over the course of a further 100,000 years, the Sun's remaining outer layers will fall away, ejecting a vast stream of matter into space and forming a halo known (misleadingly) as a planetary nebula. The ejected material will contain the helium and carbon produced by the Sun's nuclear reactions, continuing the enrichment of the interstellar medium with heavy elements for future generations of stars.[119]

text: This is a relatively peaceful event, nothing akin to a supernova, which the Sun is too small to undergo as part of its evolution. Any observer present to witness this occurrence would see a massive increase in the speed of the solar wind, but not enough to destroy a planet completely. However, the star's loss of mass could send the orbits of the surviving planets into chaos, causing some to collide, others to be ejected from the Solar System, and still others to be torn apart by tidal interactions.[120] Afterwards, all that will remain of the Sun is a white dwarf, an extraordinarily dense object, 54% its original mass but only the size of the Earth. Initially, this white dwarf may be 100 times as luminous as the Sun is now. It will consist entirely of degenerate carbon and oxygen, but will never reach temperatures hot enough to fuse these elements. Thus the white dwarf Sun will gradually cool, growing dimmer and dimmer.[121]

text: As the Sun dies, its gravitational pull on the orbiting bodies such as planets, comets and asteroids will weaken due to its mass loss. All remaining planets' orbits will expand; if Venus, Earth, and Mars still exist, their orbits will lie roughly at 1.4 AU (210,000,000 km), 1.9 AU (280,000,000 km), and 2.8 AU (420,000,000 km). They and the other remaining planets will become dark, frigid hulks, completely devoid of any form of life.[114] They will continue to orbit their star, their speed slowed due to their increased distance from the Sun and the Sun's reduced gravity. Two billion years later, when the Sun has cooled to the 6000–8000K range, the carbon and oxygen in the Sun's core will freeze, with over 90% of its remaining mass assuming a crystalline structure.[122] Eventually, after billions more years, the Sun will finally cease to shine altogether, becoming a black dwarf.[123]

text: Galactic interaction[edit]

text: The Solar System travels alone through the Milky Way in a circular orbit approximately 30,000 light years from the Galactic Centre. Its speed is about 220 km/s. The period required for the Solar System to complete one revolution around the Galactic Centre, the galactic year, is in the range of 220–250 million years. Since its formation, the Solar System has completed at least 20 such revolutions.[124]

text: Various scientists have speculated that the Solar System's path through the galaxy is a factor in the periodicity of mass extinctions observed in the Earth's fossil record. One hypothesis supposes that vertical oscillations made by the Sun as it orbits the Galactic Centre cause it to regularly pass through the galactic plane. When the Sun's orbit takes it outside the galactic disc, the influence of the galactic tide is weaker; as it re-enters the galactic disc, as it does every 20–25 million years, it comes under the influence of the far stronger "disc tides", which, according to mathematical models, increase the flux of Oort cloud comets into the Solar System by a factor of 4, leading to a massive increase in the likelihood of a devastating impact.[125]

text: However, others argue that the Sun is currently close to the galactic plane, and yet the last great extinction event was 15 million years ago. Therefore, the Sun's vertical position cannot alone explain such periodic extinctions, and that extinctions instead occur when the Sun passes through the galaxy's spiral arms. Spiral arms are home not only to larger numbers of molecular clouds, whose gravity may distort the Oort cloud, but also to higher concentrations of bright blue giants, which live for relatively short periods and then explode violently as supernovae.[126]

text: Galactic collision and planetary disruption[edit]

text: Although the vast majority of galaxies in the Universe are moving away from the Milky Way, the Andromeda Galaxy, the largest member of the Local Group of galaxies, is heading toward it at about 120 km/s.[127] In 4 billion years, Andromeda and the Milky Way will collide, causing both to deform as tidal forces distort their outer arms into vast tidal tails. If this initial disruption occurs, astronomers calculate a 12% chance that the Solar System will be pulled outward into the Milky Way's tidal tail and a 3% chance that it will become gravitationally bound to Andromeda and thus a part of that galaxy.[127] After a further series of glancing blows, during which the likelihood of the Solar System's ejection rises to 30%,[128] the galaxies' supermassive black holes will merge. Eventually, in roughly 6 billion years, the Milky Way and Andromeda will complete their merger into a giant elliptical galaxy. During the merger, if there is enough gas, the increased gravity will force the gas to the centre of the forming elliptical galaxy. This may lead to a short period of intensive star formation called a starburst.[127] In addition, the infalling gas will feed the newly formed black hole, transforming it into an active galactic nucleus. The force of these interactions will likely push the Solar System into the new galaxy's outer halo, leaving it relatively unscathed by the radiation from these collisions.[127][128]

text: It is a common misconception that this collision will disrupt the orbits of the planets in the Solar System. Although it is true that the gravity of passing stars can detach planets into interstellar space, distances between stars are so great that the likelihood of the Milky Way–Andromeda collision causing such disruption to any individual star system is negligible. Although the Solar System as a whole could be affected by these events, the Sun and planets are not expected to be disturbed.[129]

text: However, over time, the cumulative probability of a chance encounter with a star increases, and disruption of the planets becomes all but inevitable. Assuming that the Big Crunch or Big Rip scenarios for the end of the Universe do not occur, calculations suggest that the gravity of passing stars will have completely stripped the dead Sun of its remaining planets within 1 quadrillion (1015) years. This point marks the end of the Solar System. Although the Sun and planets may survive, the Solar System, in any meaningful sense, will cease to exist.[3]

text: Chronology[edit]

text: The time frame of the Solar System's formation has been determined using radiometric dating. Scientists estimate that the Solar System is 4.6 billion years old. The oldest known mineral grains on Earth are approximately 4.4 billion years old.[130] Rocks this old are rare, as Earth's surface is constantly being reshaped by erosion, volcanism, and plate tectonics. To estimate the age of the Solar System, scientists use meteorites, which were formed during the early condensation of the solar nebula. Almost all meteorites (see the Canyon Diablo meteorite) are found to have an age of 4.6 billion years, suggesting that the Solar System must be at least this old.[131]

text: Studies of discs around other stars have also done much to establish a time frame for Solar System formation. Stars between one and three million years old have discs rich in gas, whereas discs around stars more than 10 million years old have little to no gas, suggesting that giant planets within them have ceased forming.[30]

text: Timeline of Solar System evolution[edit]

text:
A graphical timeline is available at
Graphical timeline of Earth and Sun

text: Note: All dates and times in this chronology are approximate and should be taken as an order of magnitude indicator only.

text:
Chronology of the formation and evolution of the Solar System

Phase
Time since formation of the Sun
Time from present (approximate)
Event

Pre-Solar System
Billions of years before the formation of the Solar System
Over 4.6 billion years ago (bya)
Previous generations of stars live and die, injecting heavy elements into the interstellar medium out of which the Solar System formed.[14]

~ 50 million years before formation of the Solar System
4.6 bya
If the Solar System formed in an Orion nebula-like star-forming region, the most massive stars are formed, live their lives, die, and explode in supernova. One particular supernova, called the primal supernova, possibly triggers the formation of the Solar System.[16][17]

Formation of Sun
0–100,000 years
4.6 bya
Pre-solar nebula forms and begins to collapse. Sun begins to form.[30]

100,000 – 50 million years
4.6 bya
Sun is a T Tauri protostar.[9]

100,000 – 10 million years
4.6 bya
By 10 million years, gas in the protoplanetary disc has been blown away, and outer planet formation is likely complete.[30]

10 million – 100 million years
4.5–4.6 bya
Terrestrial planets and the Moon form. Giant impacts occur. Water delivered to Earth.[2]

Main sequence
50 million years
4.5 bya
Sun becomes a main-sequence star.[26]

200 million years
4.4 bya
Oldest known rocks on the Earth formed.[130][132]

500 million – 600 million years
4.0–4.1 bya
Resonance in Jupiter and Saturn's orbits moves Neptune out into the Kuiper belt. Late Heavy Bombardment occurs in the inner Solar System.[2]

800 million years
3.8 bya
Oldest known life on Earth.[72][132] Oort cloud reaches maximum mass.[75]

4.6 billion years
Today
Sun remains a main-sequence star, continually growing warmer and brighter by ~10% every 1 billion years.[108]

6 billion years
1.4 billion years in the future
Sun's habitable zone moves outside of the Earth's orbit, possibly shifting onto Mars's orbit.[111]

7 billion years
2.4 billion years in the future
The Milky Way and Andromeda Galaxy begin to collide. Slight chance the Solar System could be captured by Andromeda before the two galaxies fuse completely.[127]

Post–main sequence
10 billion – 12 billion years
5–7 billion years in the future
Sun starts burning hydrogen in a shell surrounding its core, ending its main sequence life. Sun begins to ascend the red giant branch of the Hertzsprung–Russell diagram, growing dramatically more luminous (by a factor of up to 2,700), larger (by a factor of up to 250 in radius), and cooler (down to 2600 K): Sun is now a red giant. Mercury and possibly Venus and Earth are swallowed.[109][114] Saturn's moon Titan may become habitable.[116]

~ 12 billion years
~ 7 billion years in the future
Sun passes through helium-burning horizontal-branch and asymptotic-giant-branch phases, losing a total of ~30% of its mass in all post-main-sequence phases. The asymptotic-giant-branch phase ends with the ejection of a planetary nebula, leaving the core of the Sun behind as a white dwarf.[109][119]

Remnant Sun
~ 1 quadrillion years (1015 years)
~ 1 quadrillion years in the future
Sun cools to 5 K.[133] Gravity of passing stars detaches planets from orbits. Solar System ceases to exist.[3]


document_title: Cynthia Lamontagne

question_text: actress who played big rhonda on that 70's show

question_tokens: actress who played big rhonda on that 70 's show

text: Cynthia Lamontagne

text:
Cynthia Lamontagne

Born
(1966-02-15) February 15, 1966 (age 52)

text: Cynthia Ann LaMontagne (born February 15, 1966) is an American actress who has appeared in numerous television shows and films. She is best known for her recurring role as "Big Rhonda" in the fourth season of That '70s Show.

text: Television[edit]

text:
Eyes .... Nicole Talbert (2007)
Criminal Minds .... Becky the Reporter (uncredited) (2006)
Veronica Mars .... Catherine Lenova/Yelena Sukarenko (2005) (Episode: "Ruskie Business")
Buffy the Vampire Slayer .... Lydia (2001, 2002) (Two episodes)
That '70s Show .... Big Rhonda (2001–2002) (Six episodes)
Frasier ....Episode: 'The Ski Lodge' - played Annie, a 'sex mad' friend of Daphne who fancies Niles Crane, but Frasier thinks she fancies him. All ends in 'Theatre Farce' (1998, 2001)
Maybe This Time .... Bethany (1995)

text: Filmography[edit]

text:
Forgetting Sarah Marshall (2008) .... Female Bartender
Would I Lie to You? (2002) .... Serenity
American Virgin (1999) ... Gloria
Border to Border (1998) .... The Other Woman
My Engagement Party (1998) .... Stacy
Austin Powers: International Man of Mystery (1997) .... Fembot
American Virgin (2000) .... Gloria
The Cable Guy (1996) .... Restaurant Hostess
Flirting with Disaster (1996) .... Sandra
Carlito's Way (1993) .... Woman at Elevator


document_title: Indian 500-rupee note

question_text: how many languages in new 500 rupee note

text: Indian 500-rupee note

text: History[edit]

text: The ₹500 banknote denomination was first introduced by the Reserve Bank of India (RBI) in October 1987 in order to contain the increasing number of banknotes in circulation, due to inflation.[1] The note prominently featured the portrait of Mahatma Gandhi instead of the Emblem of India, the Lion Capital of Sarnath. The popularity of this design led to the eventual redesign of the motifs of other Indian banknotes and the introduction of the first Mahatma Gandhi Series banknotes.

text: On 8 November 2016, Indian prime minister Narendra Modi announced the demonetization of the ₹500 banknotes of the Mahatma Gandhi Series as a measure to fight corruption in India and address the issue of counterfeit banknotes.[2][3][4][5][6][7] On 10 November 2016, the previous banknote was replaced by a new ₹500 banknote of the Mahatma Gandhi New Series of banknotes.[8]

text: Mahatma Gandhi New Series[edit]

text: Design[edit]

text: The ₹500 banknote of the Mahatma Gandhi New Series is 66mm x 150mm stone grey coloured, with the obverse side featuring a portrait of Mahatma Gandhi as well as the Ashoka Pillar Emblem, with a signature of the governor of Reserve Bank of India. It has the Braille feature to assist the visually challenged in identifying the currency. The reverse side features a motif of the Indian heritage site of Red Fort, and the logo and a tag line of Swachh Bharat Abhiyan.[8]

text: Security features[edit]

text:
See through register with denominational numeral 500
Latent image with denominational numeral 500
Micro letters ‘RBI’ and ‘500’ on the left side of the banknote
Windowed security thread with inscriptions ‘भारत’, RBI and 500 on banknotes with colour shift. Colour of the thread changes from green to blue when the note is tilted
Denominational numeral with Rupee Symbol, ₹500 in colour changing ink (green to blue) on bottom right
Ashoka Pillar emblem on the right Mahatma Gandhi portrait and electrotype (500) watermarks
Number panel with numerals growing from small to big on the top left side and bottom right side.
For visually impaired Intaglio or raised printing of Mahatma Gandhi portrait, Ashoka Pillar emblem, bleed lines and identity mark
Horizontal rectangle with ₹500 in raised print on the right

text: Mahatma Gandhi Series[edit]

text: Design[edit]

text: The ₹500 banknote of the Mahatma Gandhi Series is 167 × 73 mm Orange-yellow coloured, with the obverse side featuring a portrait of Mahatma Gandhi with a signature of the governor of the Reserve Bank of India. It has the Braille feature to assist the visually challenged in identifying the currency. The reverse side features the Salt March.

text: As of 2011, the new ₹ sign has been incorporated into banknote of ₹500.[9] In January 2014 RBI announced that it would be withdrawing from circulation all banknotes printed prior to 2005 by 31 March 2014. The deadline was later extended to 1 January 2015. Further deadline was extended until 30 June 2016.[10]

text: Security features[edit]

text: The security features of the ₹500 banknote includes:[11]

text:
A windowed security thread that reads 'भारत' (Bharat in the Devanagari script) and 'RBI' alternately.
Latent image of the value of the banknote on the vertical band next to the right hand side of Mahatma Gandhi’s portrait.
Watermark of Mahatma Gandhi that is a mirror image of the main portrait.
The number panel of the banknote is printed in embedded fluorescent fibers and optically variable ink.
Since 2005 additional security features like machine-readable security thread, electrotype watermark, and year of print appears on the bank note.

text: Discontinuation[edit]

text: Starting from midnight 8 November 2016 all ₹500 and ₹1000 banknotes of the Mahatma Gandhi Series ceased to be a form of legal tender after a televised address to India by Prime Minister Narendra Modi.[12]

text: Languages[edit]

text: As like the other Indian rupee banknotes, the ₹500 banknote has its amount written in 17 languages. On the obverse, the denomination is written in English and Hindi. On the reverse is a language panel which displays the denomination of the note in 15 of the 22 official languages of India. The languages are displayed in alphabetical order. Languages included on the panel are Assamese, Bengali, Gujarati, Kannada, Kashmiri, Konkani, Malayalam, Marathi, Nepali, Odia, Punjabi, Sanskrit, Tamil, Telugu and Urdu.

text:
Denominations in central level official languages (At below either ends)

Language
₹500

English
Five hundred rupees

Hindi
पाँच सौ रुपये

Denominations in 15 state level/other official languages (As seen on the language panel)

Assamese
পাঁচশ টকা

Bengali
পাঁচশ টাকা

Gujarati
પાંચ સો રૂપિયા

Kannada
ಐನೂರು ರುಪಾಯಿಗಳು

Kashmiri
پاژشھ ھطم رۄپے

Konkani
पाचशें रुपया

Malayalam
അഞ്ഞൂറു രൂപ

Marathi
पाचशे रुपये

Nepali
पाँच सय रुपियाँ

Odia
ପାଞ୍ଚ ଶତ ଟଙ୍କା

Punjabi
ਪੰਜ ਸੌ ਰੁਪਏ

Sanskrit
पञ्चशतं रूप्यकाणि

Tamil
ஐந்நூறு ரூபாய்

Telugu
ఐదువందల రూపాయలు

Urdu
پانچ سو روپے


document_title: Tinel's sign

question_text: the tinels tap test is useful to determine what

text: Tinel's sign

text:
Tinel's sign

Transverse section across the wrist and digits. (The median nerve is the yellow dot near the center. The carpal tunnel is not labeled, but the circular structure surrounding the median nerve is visible.)

Classification and external resources

Specialty
neurology

ICD-10
G56.0

ICD-9-CM
354.0

OMIM
115430

DiseasesDB
2156

MedlinePlus
000433

eMedicine
orthoped/455 pmr/21 emerg/83 radio/135

MeSH
D002349

[edit on Wikidata]

text: Tinel's sign is a way to detect irritated nerves. It is performed by lightly tapping (percussing) over the nerve to elicit a sensation of tingling or "pins and needles" in the distribution of the nerve. It takes its name from French neurologist Jules Tinel (1879–1952).[1][2][3]

text: For example, in carpal tunnel syndrome where the median nerve is compressed at the wrist, Tinel's sign is often "positive" causing tingling in the thumb, index, middle finger and the radial half of the fourth digit. Tinel's sign is sometimes referred to as "distal tingling on percussion" or DTP. This distal sign of regeneration can be expected during different stage of somatosensory recovery.[4]

text: Although most frequently associated with carpal tunnel syndrome, Tinel's sign is a generalized term, and can also be positive in tarsal tunnel syndrome, or in ulnar nerve impingement at the wrist (Guyon's canal syndrome), where it affects the other (ulnar) half of the fourth digit and the fifth digit.