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User:Marshallsumter/Theoretical astronomy

Astronomy focuses on celestial objects, space, and the physical universe as a whole. Observations of the Sun, Moon, stars, and planets have formed the basis of timekeeping and navigation.

Astronomy is a branch of science, but unlike other sciences, which have Earth-based laboratories in which controlled experiments are performed, astronomy has its labs located in the heavens far beyond the reach, let alone control, of the terrestrial observer.

History
Ptolemy's Almagest, although a brilliant treatise on theoretical astronomy combined with a practical handbook for computation, nevertheless includes many compromises to reconcile discordant observations. Theoretical astronomy is usually assumed to have begun with Johannes Kepler (1571–1630), and Kepler’s laws. It is co-equal with observation. The general history of astronomy deals with the history of the descriptive and theoretical astronomy of the solar system, from the late sixteenth century to the end of the nineteenth century. The major categories of works on the history of modern astronomy include general histories, national and institutional histories, instrumentation, descriptive astronomy, theoretical astronomy, positional astronomy, and astrophysics. Astronomy was early to adopt computational techniques to model stellar and galactic formation and celestial mechanics. From the point of view of theoretical astronomy, not only must the mathematical expression be reasonably accurate but it should preferably exist in a form which is amenable to further mathematical analysis when used in specific problems. Most of theoretical astronomy uses Newtonian theory of gravitation, considering that the effects of general relativity are weak for most celestial objects. The obvious fact is that theoretical astronomy cannot (and does not try) to predict the position, size and temperature of every star in the heavens. Theoretical astronomy by and large has concentrated upon analyzing the apparently complex but periodic motions of celestial objects.

Technology
Try combinations like theoretical astronomical technology on Google scholar.

Theoretical technological astronomy may involve time keeping, spatial positioning, and spectral resolution.

Geography
Various theories about events observed in the sky have developed at different geographical locations.

Astrophysics
Physics has helped in the elucidation of astronomical phenomena.

Integrating astronomy with physics involves

The aim of astronomy is to understand the physics and chemistry from the laboratory that is behind cosmic events so as to enrich our understanding of the cosmos and of these sciences as well.

Astronomical physics
Astronomy has helped in the elucidation of physical phenomena.

The discovery of the law of gravitation comes from the information provided by the motion of the Moon and the planets.

The viability of nuclear fusion is demonstrated in the Sun and stars and yet to be reproduced on Earth in a controlled form.

Mathematical astronomy
Theoretical astronomers use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational  numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.

Orbits
The solar antapex is a point within the constellation of Carina just south of Eta Carinae which the Sun's total motion now is directed away from at right ascension (RA) 8.4h declination -62°.[1]

There are directions of the standard antapex, the old Lick antapex (Klemola & Vasilevskis 1971),[2] the new Lick antapex (Hanson 1987)[3] and the antapex for the Galactic globular cluster system of Mihalas & Binney (1981)[4].[5]

There is a direction to the standard solar antapex.[2]

The standard solar antapex is at ℓ = 204°, b = -22°, RA 05h 17m 16.50s Dec -02° 26? 49.4?,[6][7] in Lepus.

At an early time the solar antapex is within the constellation of Carina just south of Eta Carinae which the Sun's total motion is directed away from at B1950.0 right ascension (RA) 8.4h declination -62° around 1970.[1]

Columba is the constellation that is at the solar antapex[8] - the Earth (and Sun) is moving away from its direction as the solar system moves through space.

The solar antapex, the direction opposite of the solar apex, is located near the star Zeta Canis Minoris, at J2000.0 RA 07h 51m 42.0.s Dec +01° 46? 01?.

Six objects: H-H 30, HL Tauri, XZ Tauri, and LKH? 266, 267, and 359, show common proper motion within their roughly comparable errors of measurement.[9] "Their mean motion is in the general direction of the solar antapex and is significantly larger than the correction from relative to absolute proper motion. If we assume that the component of this motion toward the antapex is due entirely to solar motion rather than a peculiar velocity of the group we can estimate the group's distance as 80 pc using the basic solar motion or 120 pc using the standard solar motion."[9]

The direction towards the solar antapex is only 10° from the direction of the Pleiades motion.[10] "Even though the direction of the Pleiades motion is near the direction to the solar antapex, the motion is large enough to place the Pleiades in a sparsely populated region of the proper motion vector point diagram."[10]

Proper motions of the M stars in the region of the Pleiades for some 31 stars shows a small grouping of 18 stars with a direction corresponding to motion towards the solar antapex.[11]

The convergent point of the Scorpio-Centaurus association is near the solar antapex, though the near parallelism of the motions, the unfavorable elongation of the cluster, and the errors in the fundamental proper-motion system make for some uncertainty in this result.[8] The convergent point at ℓ≈ 238°, b ≈ -27°, RA 05h 47m 18.73s Dec -32° 53? 16.2?, in the constellation Columba, for 1967, is clearly compatible with the Pleiades-group motion.[8] The vicinity of the solar antapex is RA (?), Dec (?), (6h < ? < 9h, -20° > ? > -50°).[8] The Sun may be located on the leading edge of a belt (Gould's Belt) of gas and dust which is partially condensed into stars, inclined at 20° to the galactic plane, and apparently linked to the lower edge of the Orion spiral arm.[8]

Several groups of Scorpio-Centaurus stars have convergents that are essentially at the solar antapex:[6]

Proper motions are used to find the convergent point of the Cassiopeia-Taurus group of some 49 stars.[13] The convergent point is close to the average ℓ(group I) = 198°, b = -11°, ℓ(group II) = 195°, b = -11°, where the convergent is about 15° away from the standard solar antapex.[13] For group I, RA is 05h 44m 30.36s Dec 07° 56? 17.6? in Orion, and group II, RA 05h 38m 30.77s Dec 10° 29? 05.4? also in Orion.

Astrochemistry
Astrochemistry, the overlap of the disciplines of astronomy and chemistry, is the study of the abundance and reactions of chemical elements and molecules in space, and their interaction with radiation. The formation, atomic and chemical composition, evolution and fate of molecular gas clouds, is of special interest because it is from these clouds that solar systems form.

Infrared astronomy, for example, has revealed that the interstellar medium contains a suite of complex gas-phase carbon compounds called aromatic hydrocarbons, often abbreviated (PAHs or PACs). These molecules composed primarily of fused rings of carbon (either neutral or in an ionized state) are said to be the most common class of carbon compound in the galaxy. They are also the most common class of carbon molecule in meteorites and in cometary and asteroidal dust (cosmic dust). These compounds, as well as the amino acids, nucleobases, and many other compounds in meteorites, carry deuterium and isotopes of carbon, nitrogen, and oxygen that are very rare on earth, attesting to their extraterrestrial origin. The PAHs are thought to form in hot circumstellar environments (around dying carbon rich red giant stars).

The sparseness of interstellar and interplanetary space results in some unusual chemistry, since symmetry-forbidden reactions cannot occur except on the longest of timescales. For this reason, molecules and molecular ions which are unstable on Earth can be highly abundant in space, for example the H3+ ion. Astrochemistry overlaps with astrophysics and nuclear physics in characterizing the nuclear reactions which occur in stars, the consequences for stellar evolution, as well as stellar 'generations'. Indeed, the nuclear reactions in stars produce every naturally-occurring chemical element. As the stellar 'generations' advance, the mass of the newly-formed elements increases. A first-generation star uses elemental hydrogen (H) as a fuel source and produces helium (He). Hydrogen is the most abundant element, and it is the basic building block for all other elements as its nucleus has only one proton. Gravitational pull toward the center of a star creates massive amounts of heat and pressure, which cause nuclear fusion. Through this process of merging nuclear mass, heavier elements are formed. Lithium, carbon, nitrogen and oxygen are examples of elements that form in stellar fusion. After many stellar generations, very heavy elements are formed (e.g. iron and lead).

Astronomical chemistry
When phenomena are observed outside the chemistry laboratory, chemists strive to determined under controlled conditions within the laboratory what has produced the phenomena.

Tools of theoretical astronomy
Theorists in astronomy endeavor to create theoretical models and figure out the observational consequences of those models. This helps observers look for data that can refute a model or help in choosing between several alternate or conflicting models.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Topics of theoretical astronomy
Topics studied by theoretical astronomers include:
 * 1) stellar dynamics and evolution;
 * 2) galaxy formation;
 * 3) large-scale structure  of matter  in the Universe;
 * 4) origin of cosmic rays;
 * 5) general relativity and physical cosmology, including string cosmology and astroparticle physics.

Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Astronomical models
Some widely accepted and studied theories and models in astronomy, now included in the Lambda-CDM model are the Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics.

A few examples of this process:

Leading topics in theoretical astronomy
Dark matter and dark energy are the current leading topics in astronomy, as their discovery and controversy originated during the study of the galaxies.

Theoretical astrophysics
Of the topics approached with the tools of theoretical physics, particular consideration is often given to stellar photospheres, stellar atmospheres, the solar atmosphere, planetary atmospheres, gaseous nebulae, nonstationary stars, and the interstellar medium. Special attention is given to the internal structure of stars.

Weak equivalence principle
The observation of a neutrino burst within 3 h of the associated optical burst from Supernova 1987A in the Large Magellanic Cloud (LMC) gave theoretical astrophysicists an opportunity to test that neutrinos and photons follow the same trajectories in the gravitational field of the galaxy.

Thermodynamics for stationary black holes
A general form of the first law of thermodynamics for stationary black holes can be derived from the microcanonical functional integral for the gravitational field. The boundary data are the thermodynamical extensive variables, including the energy and angular momentum of the system. For the simpler case of nonrelativistic mechanics as is often observed in astrophysical phenomena associated with a black hole event horizon, the density of states can be expressed as a real-time functional integral and subsequently used to deduce Feynman's imaginary-time functional integral for the canonical partition function.
 * 1) the gravitational field as described with a micocanonical system in a spatially finite region and
 * 2) the density of states expressed formally as a functional integral over Lorentzian metrics and as a functional of the geometrical boundary data that are fixed in the corresponding action,

Theoretical astrochemistry
Reaction equations and large reaction networks are an important tool in theoretical astrochemistry, especially as applied to the gas-grain chemistry of the interstellar medium. Theoretical astrochemistry offers the prospect of being able to place constraints on the inventory of organics for exogenous delivery to the early Earth.

Interstellar organics
"An important goal for theoretical astrochemistry is to elucidate which organics are of true interstellar origin, and to identify possible interstellar precursors and reaction pathways for those molecules which are the result of aqueous alterations." One of the ways this goal can be achieved is through the study of carbonaceous material as found in some meteorites. Carbonaceous chondrites (such as C1 and C2) include organic compounds such as amines and amides; alcohols, aldehydes, and ketones; aliphatic and aromatic hydrocarbons; sulfonic and phosphonic acids; amino, hydroxycarboxylic, and carboxylic acids; purines and pyrimidines; and kerogen-type material. The organic inventories of primitive meteorites display large and variable enrichments in deuterium, 13C and 15N which is indicative of their retention of an interstellar heritage.

Chemistry in cometary comae
The chemical composition of comets should reflect both the conditions in the outer solar nebula some 4.5 x 109 ayr, and the nature of the natal interstellar cloud from which the Solar system was formed. While comets retain a strong signature of their ultimate interstellar origins, significant processing must have occurred in the protosolar nebula. Early models of coma chemistry showed that reactions can occur rapidly in the inner coma, where the most important reactions are proton transfer reactions. Such reactions can potentially cycle deuterium between the different coma molecules, altering the initial D/H ratios released from the nuclear ice, and necessitating the construction of accurate models of cometary deuterium chemistry, so that gas-phase coma observations can be safely extrapolated to give nuclear D/H ratios.

Theoretical chemical astronomy
While the lines of conceptual understanding between theoretical astrochemistry and theoretical chemical astronomy often become blurred so that the goals and tools are the same, there are subtle differences between the two sciences. Theoretical chemistry as applied to astronomy seeks to find new ways to observe chemicals in celestial objects, for example. This often leads to theoretical astrochemistry having to seek new ways to describe or explain those same observations.

Astronomical spectroscopy
The new era of chemical astronomy had to await the clear enunciation of the chemical principles of spectroscopy and the applicable theory.

Chemistry of dust condensation
Supernova radioactivity dominates light curves and the chemistry of dust condensation is also dominated by radioactivity. Dust is usually either carbon or oxides depending on which is more abundant, but Compton electrons dissociate the CO molecule in about one month. The new chemical astronomy of supernova solids depends on the supernova radioactivity:
 * 1) the radiogenesis of 44Ca from 44Ti decay after carbon condensation establishes their supernova source,
 * 2) their opacity suffices to shift emission lines blueward after 500 d and emits significant infrared luminosity,
 * 3) parallel kinetic rates determine trace isotopes in meteoritic supernova graphites,
 * 4) the chemistry is kinetic rather than due to thermal equilibrium and
 * 5) is made possible by radiodeactivation of the CO trap for carbon.

Theoretical physical astronomy
Like theoretical chemical astronomy, the lines of conceptual understanding between theoretical astrophysics and theoretical physical astronomy are often blurred, but, again, there are subtle differences between these two sciences. Theoretical physics as applied to astronomy seeks to find new ways to observe physical phenomena in celestial objects and what to look for, for example. This often leads to theoretical astrophysics having to seek new ways to describe or explain those same observations, with hopefully a convergence to improve our understanding of the local environment of Earth and the physical Universe.

Weak interaction and nuclear double beta decay
Nuclear matrix elements of relevant operators as extracted from data and from a shell-model and theoretical approximations both for the two-neutrino and neutrinoless modes of decay are used to explain the weak interaction and nuclear structure aspects of nuclear double beta decay.

Neutron-rich isotopes
New neutron-rich isotopes, 34Ne, 37Na, and 43Si have been produced unambiguously for the first time, and convincing evidence for the particle instability of three others, 33Ne, 36Na, and 39Mg has been obtained. These experimental findings compare with recent theoretical predictions.

Theory of astronomical time keeping
Until recently all the time units that appear natural to us are caused by astronomical phenomena:
 * 1) Earth's orbit around the Sun => the year, and the seasons,
 * 2) Moon's orbit around the Earth => the month,
 * 3) Earth's rotation and the succession of brightness and darkness => the day (and night).

High precision appears problematic:
 * 1) amibiguities arise in the exact definition of a rotation or revolution,
 * 2) some astronomical processes are uneven and irregular, such as the noncommensurability of year, month, and day,
 * 3) there are a multitude of time scales and calendars to solve the first two problems.

Some of these time scales are sidereal time, solar time, and universal time.

Atomic time
From the Systeme Internationale (SI) comes the second as defined by the duration of 9 192 631 770 cycles of a particular hyperfine structure transition in the ground state of 133Cesium. For practical usability a device is required that attempts to produce the SI second (s) such as an atomic clock. But not all such clocks agree. The weighted mean of many clocks distributed over the whole Earth defines the Temps Atomique International; i.e., the Atomic Time TAI. From the General theory of relativity the time measured depends on the altitude on Earth and the spatial velocity of the clock so that TAI refers to a location on sea level that rotates with the Earth.

Ephemeris time
Since the Earth's rotation is irregular, any time scale derived from it such as Greenwich Mean Time led to recurring problems in predicting the Ephemerides for the positions of the Moon, Sun, planets and their natural satellites. In 1976 the International Astronomical Union (IAU) resolved that the theoretical basis for ephemeris time (ET) was wholly non-relativistic, and therefore, beginning in 1984 ephemeris time would be replaced by two further time scales with allowance for relativistic corrections. Their names, assigned in 1979, emphasized their dynamical nature or origin, Barycentric Dynamical Time (TDB) and Terrestrial Dynamical Time (TDT). Both were defined for continuity with ET and were based on what had become the standard SI second, which in turn had been derived from the measured second of ET.

During the period 1991-2006, the TDB and TDT time scales were both redefined and replaced, owing to difficulties or inconsistencies in their original definitions. The current fundamental relativistic time scales are Geocentric Coordinate Time (TCG) and Barycentric Coordinate Time (TCB). Both of these have rates that are based on the SI second in respective reference frames (and hypothetically outside the relevant gravity well), but due to relativistic effects, their rates would appear slightly faster when observed at the Earth's surface, and therefore diverge from local Earth-based time scales using the SI second at the earth's surface.

The currently defined IAU time scales also include Terrestrial Time (TT)(replacing TDT, and now defined as a re-scaling of TCG, chosen to give TT a rate that matches the SI second when observed at the Earth's surface), and a redefined Barycentric Dynamical Time (TDB), a re-scaling of TCB to give TDB a rate that matches the SI second at the Earth's surface.

Stellar dynamical time scale
For a star, the dynamical time scale is defined as the time that would be taken for a test particle released at the surface to fall under the star's potential to the centre point, if pressure forces were negligible. In other words, the dynamical time scale measures the amount of time it would take a certain star to collapse in the absence of any internal pressure. By appropriate manipulation of the equations of stellar structure this can be found to be

$$ \tau_{dynamical} \simeq \frac{R}{v} = \sqrt{\frac{R^3}{2GM}} \sim 1/\sqrt{G\rho} $$

where R is the radius of the star, G is the gravitational constant, M is the mass of the star and v is the escape velocity. As an example, the Sun dynamical time scale is approximately 1133 seconds. Note that the actual time it would take a star like the Sun to collapse is greater because internal pressure is present.

The 'fundamental' oscillatory mode of a star will be at approximately the dynamical time scale. Oscillations at this frequency are seen in Cepheid variables.

On Earth
The basic characteristics of applied astronomical navigation are
 * 1) usable in all areas of sailing around the Earth,
 * 2) applicable autonomously (does not depend on others - persons or states) and passively (does not emit energy),
 * 3) conditional usage via optical visibility (of horizon and celestial bodies), or state of cloudiness,
 * 4) precisional measurement, sextant is 0.1', altitude and position is between 1.5' and 3.0'.
 * 5) temporal determination takes a couple of minutes (using the most modern equipment) and ≤ 30 min (using classical equipment).

The superiority of satellite navigation systems to astronomical navigation are currently undeniable, especially with the development and use of GPS/NAVSTAR. This global satellite system
 * 1) enables automated three dimensional positioning at any moment,
 * 2) automatically determines position continuously (every second),
 * 3) determines position independent of weather conditions (visibility and cloudiness),
 * 4) determines position in real time to a few meters (two carrying frequencies) and 100 m (modest commercial receivers), which is two to three orders of magnitude better than by astronomical observation,
 * 5) is simple even without expert knowledge,
 * 6) is relatively cheap, comparable to equipment for astronomical navigation, and
 * 7) allows incorporation into integrated and automated systems of control and ship steering. The use of astronomical or celestial navigation is disappearing from the surface and beneath or above the surface of the Earth.

Geodetic astronomy is the application of astronomical methods into networks and technical projects of geodesy for
 * apparent places of stars, and their proper motions
 * precise astronomical navigation
 * astro-geodetic geoid determination and
 * modelling the rock densities of the topography and of geological layers in the subsurface
 * Satellite geodesy using the stellar background (see also astrometry and cosmic triangulation)
 * Monitoring of the Earth rotation and polar wandering
 * Contribution to the time system of physics and geosciences

Astronomical algorithms are the algorithms used to calculate ephemerides, calendars, and positions (as in celestial navigation or satellite navigation).

Many astronomical and navigational computations use the Figure of the Earth as a surface representing the Earth.

The International Earth Rotation and Reference Systems Service (IERS), formerly the International Earth Rotation Service, is the body responsible for maintaining global time and reference frame standards, notably through its Earth Orientation Parameter (EOP) and International Celestial Reference System (ICRS) groups.

Deep space
The Deep Space Network, or DSN, is an international network of large antennas and communication facilities that supports interplanetary spacecraft missions, and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. DSN is part of the NASA Jet Propulsion Laboratory (JPL).

Aboard an exploratory vehicle
An observer becomes a deep space explorer upon escaping Earth's orbit. While the Deep Space Network maintains communication and enables data download from an exploratory vessel, any local probing performed by sensors or active systems aboard usually require astronomical navigation, since the enclosing network of satellites to ensure accurate positioning is absent.


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User talk:Marshallsumter/Theoretical astronomy

Disclosure: all of the text contained in the learning resource prior to the time stamp after this disclosure are only the edits and accumulated corrections of mine to the article theoretical astronomy as it now occurs on Wikipedia. Marshallsumter 23:25, 27 October 2011 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Tectonic hazards/Earthquake loss estimation

Earthquake loss estimation, required for the seismic fitness considerations, is usually performed in terms of a Damage Ratio (DR) which is a ratio of the earthquake damage dollar amount to total value of a building. For a long time, it was associated with a collection of mass inventory data and was based, mostly, on experts' opinions. It looked, therefore, more like an art than a science.

A considerable step forward was made with the completion of project called HAZUS offering a fully computerized procedure for loss estimation. However, motion-damage relationships of HAZUS are not written in the building code language. Besides, they are based, at least partially, on experts' judgments valid just for an average construction and, therefore, most applicable for a statistically large number of facilities.

There is, also, the Damage Ratio Charts Method which is based on a consistent quantitative analysis targeting a prediction of damage ratios and employs a limited number of well-understood structural and earthquake related parameters. It establishes a direct theoretical relationship between the standard structural design procedure and the expected damage characteristics required by insurers.

The method is user-friendly: its application, supported by a site-specific evaluation, does not take more than a few days.


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Motivation and emotion/Book/2011/Facial expression

Overview

How do you react when you see someone smiling? Do you smile back? React warmly towards that person? Or do you become angry and turn away? How is that we know to interpret a lift of the upper lip as a positive sign? Facial expressions, which often occur involuntarily, are social tools critical for the development and regulation of interpersonal skills. Facial expressions refer to movements or adjustments to the facial muscles to produce universally recognised displays of emotion. Humans are born with an innate and effective way of decoding such emotional facial expressions, such as a lift of the upper lip (smile) indicating happiness. However, humans, unlike many other kinds of species, are also born with the ability to hide emotions and be deceptive to others. Fortunately (or unfortunately?), researchers have discovered many characteristics which can suggest that voluntary expressions are being produced.

These ideas are well depicted in the popular American television program Lie to Me, which is centered around a “human polygraph machine” known as Dr. Carl Lightman who, along with his team of trained deception experts, specialises in solving criminal cases by reading the emotion filled facial expressions of the suspects. The show is based on the work of leading researcher in the field of facial expressions, Paul Ekman.

The use of emotional expression as a way of communication of emotions or information has always almost existed for humans. In pre-linguistic times, humans used facial expressions to convey important information such as danger, affection, or the sight of food. However, it is only now that scientists have become to understand how and why we communicate emotions through facial expressions.

Influential Theorists
The history of research on emotional facial expression is not a long one. Currently, research goes back only as far as Charles Darwin, who in 1872 authored the evolutionary book Expression of Emotion in Man and Animals. Since then, only a handful of researchers have made significant contributions in the field of emotional expression. Dr. Paul Ekman, is credited as leading researcher in the field today, building on the works of Duchenne De Bologne, Darwin, and collaborating with researchers such as Wallace Freisen to produce theoretical concepts and models to further our understanding of facial expressions.

Charles Darwin
Charles Darwin is renowned for his evolutionary contributions to psychology, introducing concepts such as survival of the fittest and natural selection to the non-scientific world. What isn’t so well-known about him is the contribution he made to understanding emotional facial expression in humans and nonhumans. In his influential book, Expressions of Emotion in Man and Animals, Darwin draws focus to select emotions which are communicated through discrete facial movements across different cultures and species (Darwin, 1872). Darwin emphasises the process of evolution in facial expressions. He suggests that facial expressions represent adaptive features that were once functional in the past (or still are today) for either human or nonhuman species. For example, eyebrow raising (a characteristic of the emotion of surprise) increases the field of vision and allows the eyebrow to move in any direction, a highly functional action (Matsumoto & Ekman, 2007).

Paul Ekman
Unquestionably, the most influential researcher in the field of emotional expression this century is Dr. Paul Ekman. Ekman’s infatuation with understanding facial expressions began when he was teaching a young group of psychiatrists. The group wanted to know how to tell if a psychiatric patient was telling the truth about feeling better, a question which fueled intense research by Ekman (Henley, 2009). Eventually, Ekman discovered, whilst watching videos of dishonest psychiatric patients in slow motion, that vivid intense emotions flashed for 1/5th of second on the patients face, leading to the discovery of micro-expressions- "very fast, intense expressions of concealed emotion" (Henley, 2009). Over the past two decades, Ekman has been the front man in research based on understanding how and why humans communicate emotions through emotional expression. His extensive research lead to the discovery that emotional expressions are universal (Ekman, 1993), and the development of a core set of emotions (Ekman, 1992b), both of which will be discussed in more detail in the following section. Along with fellow researcher Wallace Friesen, Ekman developed the internationally renowned Facial Action Coding System (Ekman & Freiesen, 1978).

Facial Coding System
Along with fellow researcher, Wallace Friesen, Ekman co-created the Facial Action Coding System (FACS)(1978) a system for “describing all visually distinguishable facial movements” (Ekman & Freiesen, 1978). The system is based on the movement of action units (AU’s) which are anatomically related to distinct head and eye distortions and reflect a particular facial expression (Levenson & Friesen,1983). FACS consists of 46 action units, which produce around 7,000 different combinations, providing the necessary detail for describing facial expressions. For example, according to FACS, the expression of happiness involves a combination of pulling lip corners (AU 12 and 13), mouth opening (AU 25 and 27), upper lip raising (AU 10), and often burrow deepening (AU 11) (Sayette, Cohn, Wertz, Perrott, & Parrot, 2001). Today, FACS is used as an effective means of measuring facial expression, often used as a deception tool, showing the difference between a genuine and fake expression. Since its creation over 30 years ago, FACS has been updated to computer software, making the process faster and more accurate and highly accessible.

Alan Fridlund
Although the work of Darwin, Duchenne, Ekman and Freisen has gathered a lot of support, as with any scientific domain, opposing theorists still exist. Alanh Fridlund proposes what is known as the behavioural ecology theory which depicts facial expressions to be reflection of intentions rather than emotions (Fridlund, 1994). Fridlund believes that facial expressions are purely communicative signals linked to underlying emotional states. Fridlund based his theory on evolutionary grounds. He reasoned that facial displays could only evolve if they were noticed by others, essentially, facial expressions cannot evolve without social interaction (Azar, 2000). Although both Ekman and Fridlund have persuasive arguments, it is generally accepted in the scientific world that facial expressions are a product of both communicative and emotional functions.

Test Yourself: Section Review Question Which researcher was the first to suggest that facial expressions are universal?: - Paul Ekman + Charles Darwin - Alan Fridlund
 * type=""}

Universal nature of facial expressions

Early thoughts in the scientific world was that facial expressions, like language, were culture specific (Bruner and Tagiuri, 1954). However, in the late 1960’s Ekman and Tomkins began the first of many studies to show that facial expressions are universal. In the early studies, participants selected from a diverse range of cultures were required to match basic emotions with pictures of different facial expressions (Ekman, Sorenson, and Frisen, 1969). The result indicated that there were agreements across cultures in the emotion represented by the facial expression, and Ekman and colleagues concluded that this represented universality of emotional expression. At this stage, only six emotions- anger, disgust, fear, happiness, sadness and surprise- were found to be universal. However, soon critics began to question the validity of these studies, suggesting that the results might simply be due to shared visual input as all the participants used in the study where from industrialised cultures were emotions could be learned and imitated through media. In response to these claims, Ekman and Friesen studied a preliterate, isolated culture in New Guinea. They found that the tribespersons accurately identified facial expressions to match stories depicting the corresponding emotion (Ekman, & Friesen, et al, 1987). In addition, Ekman and Friesen filmed the faces of the tribesmen portraying a range of facial expressions, and showed these pictures to American participants. The American participants were able to correctly identify the emotions corresponding to the facial expressions portrayed by the New Guinea tribesmen, providing a source of evidence for universality of facial expressions, and dispelling concerns that previous results were due to shared visual input (Ekman, & Friesen, et al, 1987). However, following the publishing of these studies, critics again spoke out, this time with new concerns that the previous studies looked at judgments and not the production of facial expressions. In response, Ekman conducted another study in which he instructed Japanese and American participants to watch a emotion provoking film. He analysed the facial expressions of both participants, with results indicating that participants from both cultures displayed the same muscle movements in response to the emotional film (Matsumoto, & Ekman, 1989). Since these consecutive studies many other researchers have also demonstrated that there a number of universally recognised facial expressions (Matsumoto, 2001), and it is now generally accepted in the scientific community that facial expressions are not culturally dependent.

In addition to his research on the universality of facial expressions, Ekman also proposed the ideas of display rules to describe how different cultures teach its members different rules about the expression of emotions in social situations (Ekman, Friesen, & O’Sullivan, 1987). To show this, Ekman studied Japanese and American individuals and found that when the subjects were alone in a room there were no differences in facial expression in response to a emotional provoking film. However, when authority figures were also present in the experiment, the Japanese participants were more likely to attempt to hide negative expressions with a smile (Ekman, 1989). These cultural differences in displaying emotion may account for how on occasion some universal expressions might appear to differ within cultures.

Innate nature of facial expressions
Facial expressions are essential for communication and social interaction at all ages, however, they are especially important during the first few years of life when children are verbally less able to communicate. There is consistent evidence for the ability of infants to not only discriminate emotional expression, but to also produce facial expressions similar to the ones show by adults (Izard, 1994). A study of emotion in young infants found that at 2.5 months of age infants are able to understand expressions of sadness and anger. In addition, majority of infants were able to display basic characteristics of surprise disgust, and fear (Izard, 1994). Izard (1994) suggests that these facial expressions are indeed accurate indicators of the emotion that the infant is feeling at the time. Furthermore, studies have also shown that children who are blind or who become blind at a young age are still able to express feelings by smiling, crying, and glaring, representing the emotions of joy, sadness, and anger respectively (Eibl-Eibesfeldt, 1973). Camras (1992) studied 5 month old Japanese and American infants and found that they produced identical expressions of anger, and also sad-anger and sad-fear combinations. This study, not only shows that humans are born with an innate tendency to display emotions through facial expressions, but also supports the universality theory of facial expressions.

Facial feedback hypothesis
The Facial Feedback Hypothesis originated from the work of Darwin who was the first to propose that stimuli-evoked physiological changes have an impact on emotion, and are not just a consequence of emotion (Darwin, 1872). Fellow psychologist William James even went as far to say that emotion is the purely the awareness of physiological changes following an internal or external stimulus (Reisanzein, & Studtmann, 2007). Tomkins conceptualised these proposals to form the bases of the Facial Feedback hypothesis which suggests that facial expressions have the ability to bring about an emotional experience in an individual (Tomkins, 1962).

Lanzetta and colleagues (Lanzetta, Cartwright-Smith, & Kleck,1976) were one of the first to conduct experimental studies on the facial feedback hypothesis, finding that participants who were instructed to express an emotion had a tendency to feel that emotion more strongly. Lanzetta found that individuals who were instructed to fake a high pain threshold whilst receiving electric shocks experienced less physiological pain responses than those who were instructed to exaggerate the pain they were feeling. One well known study, which has since been replicated, involved participants holding a pencil in their mouths with either their lips (position which would contract facial muscles involved in a frown expression), or with their teeth (position that would contract the facial muscles involved in a smiling expression). The participants were then required to watch a cartoon and rate it’s comedic value. Results showed that individuals who held the pencil with their teeth (the smiling expression) rated the cartoon more favourably than those in the other condition (McIntosh, 1986). Although this study, and along with many others, favour the Facial Feedback hypothesis, there are many others that contradict this theory. In particular, critics argue that individuals who suffer from permanent facial paralysis are still able to experience emotion (Fridlund, 1994). Recently, researchers have begun to look into the effects of Botox on facial expression, with some results indicating that temporary facial paralysis has only a select effect on the processing of emotional stimuli (Ochsner, 2010), opposing the facial feedback hypothesis.

Test Yourself: Section Review Question {The six original basic emotions as proposed by Ekman and Friesen (1969) does NOT include?: - Happiness + Content - Fear - It includes all of the above.
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Deception
Body reactions, inconsistent speech patterns, and fidgeting are all commonly looked for signs of lying, however, what is often ignored are the many nonverbal facial signs of deception. In fact emotion is one of the main reasons why lies fail. Even when an individual is not lying about their emotions, there are many other emotions that occur as a result of lying such as; fear, guilt, and even excitement (Yuille, 1989). Darwin was one of the first to investigate the effect of deception on facial expression, by suggesting that actions which are cannot occur voluntarily are unable to be prevented when other involuntary processes such as emotion occur. In essence, Darwin believed that humans were unable to prevent their true emotions or feelings from being expressed facially (Darwin, 1872). In 1969, Ekman provided substantial evidence for this notion when he discovered micro-expressions- vivid intense emotions which last around 1/5 of a second- which although occur very briefly can be detected by the human eye with relevant training (Ekman, & Friesen, 1969). In addition to micro-expressions, Ekman believes there are seven other characteristics which help to distinguish whether a facial expression is occurring voluntarily or involuntarily:

 * 1) Morphology- the absence of any reliable movements can hint that the expression is voluntary
 * 2) Symmetry- asymmetry is an indication that the expression is dilberate
 * 3) Duration- very brief (less than 1/5 a second) and long (greater than 5 seconds)suggests a more deliberate than spontaneous response.
 * 4) Speed of onset- a deliberate expression will typically have a quicker onset than a spontaneous one (although this does tend to vary with social circumstances)
 * 5) Apex overlap- in expressions in which multiple facial actions are present, the apexes of the action will overlap in a voluntary expression.
 * 6) Ballistic trajectory- a voluntary expression will appear smooth over it's trajectory, without a stepped off or rough onset.
 * 7) Cohesion- the expression is spontaneous it will coincide with what is being said vocally (Ekman, 2003).

Another important behavioural cue is the distinction between enjoyment smiles and non-enjoyment smiles, as suggested by Duchenne de Boulogne (1862). It has been suggested that smiles when lying differ from involuntary smiles. One study found that woman who were instructed to conceal negative emotion and claim enjoyment displayed what is referred to as a masking smile, a superimposed expression which attempts to conceal muscular actions associated with fear, sadness, and disgust (Frank, Ekman, & Friesen, 1993). Although verbal information is very useful in determining whether a person is attempting to conceal information, Ekman has shown that nonverbal signs can also provide substantial evidence for deception.

Test Yourself: Section Review Question A sign of emotional concealment is?: - Micro-expressions - asymmetry in facial expression - very long facial expressions (longer than 5 seconds) + all of the above
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Facial Expressions
In 1969, Ekman and Friesen (with the help of Silvan Tomkins) compiled a list of what they believed to be basic human emotions (Ekman, & Friesen, 1971). These emotions were selected based on research in different cultures, in particular illiterate cultures where facial expressions can’t be taught. Ekman deems this one characteristic of a basic emotion- it must be universal. Other characteristics of a basic emotions include; it must be associated with a physiological response, there must be universal events in which these emotions occur, and the emotion must be able to be triggered immediately without conscious awareness following a internal or external stimuli. (Dagleish and Power, 1999). Below are the six basic emotions according to Ekman, and details of their corresponding facial expressions and facial muscles.

Star of Lie to Me, Tim Roth, demonstrating Ekman's six basic emotions

Fear
Fear occurs when an individual interprets a situation as dangerous or threatening, either physically or psychologically. When the fear response is activated, defense mechanisms also respond. The mechanisms include; perspiration, trembling, increased heart rate and blood pressure (Marsh, Kozak, Ambady, 2007), and facial expressions such as: wide opened eyes, lips retracted, eyebrows raised, and mouth opened (Matsumoto & Ekman, 2007).

Anger
Anger is one of the most uncomfortable emotions to experience. It often begins with a build up of other emotions such as intent, blame, or annoyance, and become expressed when an individual perceives a situation to be unsatisfactory often due to an interference of goals (Power & Dalgleish, 2008). Often anger results in acts of violence and aggression, and is best characterised by the following facial expressions: raised or flared nostrils, a furrowed brow, wide open eyes, compressed mouth, and head in an erect position (Matsumoto & Ekman, 2007).

Sadness
Sadness is an emotion that often occurs following experiences of separation or failure, and motivates an individual to initiate whatever behaviour necessary to cease the sadness provoking stimuli. Although the emotion of sadness is often only temporary, it is usually followed by prolonged feelings of sorrow and unhappiness (Reeve, 2009). Signs of sadness including crying and sobbing, and facial expressions such as depression of the corners of the mouth, and drooping of the eyelids (Matsumoto & Ekman, 2007).

Disgust
Disgust can occur in response to a variety of different objects, situations, and experiences, and therefore is a very subjective emotion. According to Reeve (2009) however, most people tend to be disgusted by things of an animal origin that can potentially spread and infect others objects. In response to feelings of disgust, an individual becomes motivated to dispel the contaminated object, producing facial characteristics such as: lower lip turned down, upper lip raised, mouth open, and protruding lips (Matsumoto & Ekman, 2007).

Happiness
The term happiness can be referred to in terms of moods, experiences, feelings and emotions. Generally, it represents an emotional state which reflects satisfaction across many different domains of life. Happiness is often associated with other emotions such as joy, exhilaration, and ecstasy (Power & Dalgleish, 2008). It is most often experienced when reaching a goal, receiving feedback, or looking forward to an upcoming event, and is best represented by a smile- wrinkled skin under the eyes, raised check bones, and mouth drawn up at the corners (Matsumoto & Ekman, 2007).

Surprise
Surprise is the briefest of all emotions, often only lasting a few seconds, after which it is then transferred into other emotions such as fear, relief, emotion, or amusement. Surprise is an emotion which can only be triggered by an unplanned event, and can be described as either a pleasant or unpleasant emotion depending on both the situation and the individual (Power & Dalgleish, 2008). Surprise is a unexpected emotion which results in dramatic facial expressions including; raised eyebrows, wrinkled forehead, open wide eyes, and gaping mouth (emotions revealed TB) (Matsumoto & Ekman, 2007).

Test Yourself: Section Review Question Mouth drawn up at corners, wrinkled skin under the eyes, and raised check bones indicate which emotion?: - Surprise - Joy + happiness
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Autism
Reading emotion filled facial expressions in others is key to social interactions as it helps to explain and anticipate other’s actions. Individuals who do not recognise these facial expressions are prone to misinterpreting information which can have detrimental effects on social interaction (Ekman, 1992). Typically, individuals with Autism have a deficit in interpreting, understanding, and responding to emotional expression (Celani et al, 1999). There are hundreds of theories to suggest why individuals with Autism struggle to understand and respond to emotional expression. One current theory, is that although individuals with Autism have the ability to perceive emotional expression, they do not give the same priority to interpreting facial expressions as typical individuals do (Celani et al, 1999). This is demonstrated in studies where participants with Autism, who are asked to pair pictures of people together, have a tendency to pair pictures on the basis of non-emotional features, such as a hat (Celani et al, 1999). Scientists in Singapore have developed a system which could potentially help Autistic individuals identify the emotion of others. The system first locates the outer edges of the face, then narrows it down to crucial features, and then classify those features into corresponding emotions (Teoh, Nguwi, Cho, 2009). This system is thought to help individuals to read the emotions in other through facial expressions, however, it does not teach them how to react to such emotions, a key deficit in individuals with Autism. Studies on individuals with Autism further deepens the understanding of facial expression in humans, and continual research in this area may potentially lead to effective management of emotion deficits in the Autistic population.