Branches of Mathematics

Pure mathematics

• Algebra
• Calculus
• Geometry
• Topology
• Trignometry
• Combinatorics
• Logic
• Number theory

Applied mathematics

• Dynamical systems and differential equations
• Mathematical physics
• Computing
• Information theory and signal processing
• Probability and statistics
• Game theory
• Operations research

Related Topics

• Electromagnetic Spectrum
• Linear Equations
• Applied Physics
• Nano Technology
• Engineering Sciences
• Mathematical Medicine
• Fluid dynamics
• Computational Mathematics
• Gamma Ray Optics
• Onfrared Optics
• Relative Velocity
• Iciam
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• Biomedical Engineering
• Neuroscience Research
• Quantum Cosmology
• Brain Research

• 1 E-6 s
• 1 E-9 s
• 1 E3 s
• 12-hour clock
• 24-hour clock
• Absolute zero
• Abū Rayḥān al-Bīrūnī
• Al-Biruni
• Altitude
• Ampere
• Anchor escapement
• Arrow of time
• ArXiv
• Astrarium
• Astronomical Journal
• Astronomical unit
• Atomic clock
• Atomic mass unit
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• Attosecond
• B-Theory of time
• Babylonia
• Becquerel
• Bibcode
• BIPM
• Black body
• Caesium
• Caesium fountain
• Calendar
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• Circadian rhythm
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• Conversion of units
• Coordinate time
• Cosmological decade
• Coulomb
• Day
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• Decibel
• Decimal time
• Deep time
• Degree (angle)
• Discrete time
• Dominical letter
• Dreamtime
• DUT1
• Earth
• Electric field
• Electronvolt
• Endurantism
• Epact
• Ephemeris second
• Ephemeris time
• Epoch (astronomy)
• Equation of time
• Equinox
• Ernest William Brown
• Eternal return
• Eternity
• Event (philosophy)
• Exponentiation
• Farad
• Femtosecond
• Fortnight
• Future
• Futures studies
• G. J. Toomer
• Galactic year
• Geochronology
• Geoid
• Geologic time scale
• Gigasecond
• Grandfather clock
• Gray (unit)
• Greenwich Mean Time
• Gregorian calendar
• Hebrew calendar
• Hectare
• Helek
• Hellenistic
• Henry (unit)
• Hertz
• Hexadecimal time
• Hipparchus
• History
• Horology
• Hour
• Hourglass
• Illumin
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• Imperial units
• Intercalation
• Islamic calendar
• ISO 31-1
• ISO 8601
• Jiffy (time)
• Jost Bürgi
• Joule
• Julian calendar
• Kalachakra
• Katal
• Kelvin
• Kilogram
• Kilosecond
• Kāla (time)
• Leap second
• Leap year
• Litre
• London
• Long Now Foundation
• Louis Essen
• Lumen (unit)
• Lunar calendar
• Lunisolar calendar
• Lustrum
• Lux
• Magnetic field
• Magneto-optical trap
• Marin Mersenne
• Marine chronometer
• Marine sandglass
• Mean sea level
• Megasecond
• Mental chronometry
• Metre
• Metric time
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• Metrology
• Microsecond
• Millennium
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• Minute
• Minute of arc
• Mks system of units
• Mole (unit)
• Month
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• Nanosecond
• Natural units
• Neper
• New SI definitions
• Newton (unit)
• NIST
• Nuclear time scale
• Ohm
• Orpheus
• Pascal (unit)
• Past
• Pendulum clock
• Perdurantism
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• Persian people
• Picosecond
• Planck epoch
• Planck time
• Polish language
• Portal Time
• Present
• Prime Meridian
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• Ptolemy
• Radian
• Radio clock
• Radio station
• Regnal year
• Revolution in Time
• Roger Bacon
• Saeculum
• Second
• Second of arc
• Seconds pendulum
• Sense of time
• Seven-day week
• Sexagesimal
• Shake (unit)
• SI
• SI base unit
• SI derived unit
• SI prefix
• Sidereal time
• Siemens (unit)
• Sievert
• Solar calendar
• Solar time
• Solstice
• Space
• Spacetime
• Specious present
• Springer-Verlag
• Standard gravity
• Steradian
• Sundial
• System time
• T-symmetry
• Template Time topics
• Temporal finitism
• Temporal parts
• Tempus fugit
• Terrestrial Time
• Tesla (unit)
• Theory of relativity
• Tide (time)
• Time
• Time Banking
• Time capsule
• Time dilation
• Time discipline
• Time domain
• Time in physics
• Time signature
• Time standard
• Time travel
• Time use research
• Time value of money
• Time zone
• Time-based currency
• Timekeeper
• Timeline
• Tonne
• Tropical year
• Turkish language
• Tycho Brahe
• Unit of time
• Universal Time
• Universal time
• UTC offset
• Verge escapement
• Volt
• Watch
• Water clock
• Watt
• Weber (unit)
• Week
• Weekday names
• Wheel of time
• William Clement
• William Markowitz
• WWV (radio station)
• Year
• ΔT
• 
  

• 
  Hectare
  The hectare ( /ˈhɛktɛər/ or /ˈhɛktɑr/; symbol ha) is a metric unit of area defined as 10,000 square metres (100 m by 100 m), and primarily used in the measurement of land. In 1795, when the metric system was introduced, the 'are' was defined as being 100 square metres and the hectare ('hecto-' + 'are') was thus 100 'ares' or 1/100 km². A hectare of land is about 2.47 acres.
  When the metric system was further rationalised in 1960, resulting in the International System of Units (SI), the are was not included as a recognised unit. The hectare is one of the non-SI units accepted for use with the SI units.
  The metric system of measure was first given a legal basis in 1795 by the French Revolutionary government. The law of 18 Germinal, Year III (7 April 1795) defined five units of measure:
  Although the law defined the length of the metre, there was no practical way of accurately measuring the metre (and hence the are) until 1799 when the first standard metre was manufactured and adopted.
  The standard metre remained in the custody of successive French governments until 1875 when, under the Convention of the Metre, its supervision passed into international control under the auspices of the General Conference on Weights and Measures (GCPM). At the first meeting of the GCPM in 1889 when a new standard metre, manufactured by Johnson Matthey & Co of London was adopted, the are and hectare were automatically redefined.
  
  wn.com/Hectare
• 
  London
  London ⁱ/ˈlʌndən/ is the capital city of England and the United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its founding by the Romans, who named it Londinium. London's ancient core, the City of London, largely retains its square-mile mediaeval boundaries. Since at least the 19th century, the name London has also referred to the metropolis developed around this core. The bulk of this conurbation forms the London region and the Greater London administrative area, governed by the elected Mayor of London and the London Assembly.
  London is a leading global city, with strengths in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism and transport all contributing to its prominence. It is the world's leading financial centre alongside New York City and has the fifth-largest city GDP in the world (and the largest in Europe). London has been described as a world cultural capital. It was the world's most visited city during 2011 and London Heathrow is the world's busiest airport by number of international passengers. London's 43 universities form the largest concentration of higher education in Europe. In 2012 London will become the first city to host the modern Summer Olympic Games three times.
  
  wn.com/London
• 
  Watt
  The watt ( /ˈwɒt/ WOT; symbol: W) is a derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit, defined as one joule per second, measures the rate of energy conversion or transfer.
  
  
  
  
  ) is the SI derived unit of electrical resistance.
  The watt is named after the Scottish scientist James Watt for his contributions to the development of the steam engine. The unit was recognized by the Second Congress of the British Association for the Advancement of Science in 1882. The 11th General Conference on Weights and Measures in 1960 adopted it for the measurement of power into the International System of Units (SI).
  The femtowatt is equal to one quadrillionth (10⁻¹⁵) of a watt. Technologically important powers that are measured in femtowatts are typically found in reference(s) to radio and radar receivers. For example, meaningful FM tuner performance figures for sensitivity, quieting and signal-to-noise require that the RF energy applied to the antenna input be specified. These input levels are often stated in dBf (decibels referenced to 1 femtowatt). This is 0.2739 microvolt across a 75 ohm load or 0.5477 microvolt across a 300 ohm load; the specification takes into account the RF input impedance of the tuner.
  
  wn.com/Watt

• Ernest William Brown
  Ernest William Brown FRS (29 November 1866 – 22 July 1938) was a British mathematician and astronomer, who spent the majority of his career working in the United States.
  His life's work was the study of the Moon's motion (lunar theory) and the compilation of extremely accurate lunar tables. He also studied the motion of the planets and calculated the orbits of Trojan asteroids.
  Brown was born in Hull, England, the only son of William and Emma (Martin) Brown. He was educated at Hull and East Riding College. After leaving school, he entered Christ's College, Cambridge, where he graduated with first-class honours in mathematics in 1887. He continued with post-graduate studies at Cambridge and worked under the direction of George Howard Darwin. In the summer of 1888, Darwin suggested that Brown study the papers of George William Hill on the lunar theory. As it turned out, this idea for a line of research was to have a major impact on the remainder of Brown's life.
  Brown was made a fellow of Christ's College in 1889, and received his Masters degree in 1891. He then left England to take up a place as a mathematics instructor at Haverford College, Pennsylvania. There, he rose rapidly to the position of Professor of Mathematics in 1893.
  
  wn.com/Ernest_William_Brown
• 
  Hipparchus
  Hipparchus/hɪˈpɑːrkəs/, or more correctly Hipparchos (Greek: Ἵππαρχος, Hipparkhos; c. 190 BC – c. 120 BC), was a Greek astronomer, geographer, and mathematician of the Hellenistic period. He is considered the founder of trigonometry.
  Hipparchus was born in Nicaea (now Iznik, Turkey), and probably died on the island of Rhodes. He is known to have been a working astronomer at least from 162 to 127 BC. Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity. He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Chaldeans from Babylonia. He developed trigonometry and constructed trigonometric tables, and he solved several problems of spherical trigonometry. With his solar and lunar theories and his trigonometry, he may have been the first to develop a reliable method to predict solar eclipses. His other reputed achievements include the discovery of Earth's precession, the compilation of the first comprehensive star catalog of the western world, and possibly the invention of the astrolabe, also of the armillary sphere, which he used during the creation of much of the star catalogue. It would be three centuries before Claudius Ptolemaeus' synthesis of astronomy would supersede the work of Hipparchus; it is heavily dependent on it in many areas.
  
  wn.com/Hipparchus
• 
  Jost Bürgi
  Jost Bürgi, or Joost, or Jobst Bürgi (February 28, 1552, Lichtensteig, Switzerland – January 31, 1632), active primarily at the courts in Kassel and Prague, was a Swiss clockmaker, a maker of astronomical instruments and a mathematician.
  Jost Bürgi is widely considered one of the most innovative and most skillful 'mechanics' of his era. It has been suggested that he should also be counted among the leading astronomers of his time because his unprecedented ability to design and construct mechanical models of the movement of heavenly bodies proves an advanced level of insight into celestial mechanics. His classification as a scholar is controversial because he lacked a formal education and did not know Latin, the only language of scholarly publications at the time. Another autodidact, Nicolaus Reimers, in 1587 translated Copernicus' De Revolutionibus Orbium Coelestium into German for Bürgi. A copy of the translation survived in Graz, it is thus called "Grazer Handschrift".
  He left few written records of his work. However other historians of science claim that Bürgi's legacy of many unique and innovative mechanical astronomical models should be considered an unorthodox method of 'publishing' astronomical insights. During his years in Praha he worked closely with the astronomer Johannes Kepler at the court of Rudolf II.
  
  wn.com/Jost_Bürgi
• 
  Louis Essen
  Louis Essen FRSO.B.E. (6 September 1908 – 24 August 1997) was an English physicist whose most notable achievements were in the precise measurement of time and the determination of the speed of light. He was critical of Albert Einstein's theory of relativity, particularly as it related to time dilation.
  Born in Nottingham, Essen earned his degree in physics from the University of London in 1928, having studied at University College Nottingham. He started work at the National Physical Laboratory (NPL) the following year, under D. W. Dye, investigating the potential of tuning forks and quartz crystal oscillators for precise time measurement. His research led to his development of the quartz ring clock in 1938, the clock soon becoming a standard for time measurement at observatories throughout the world.
  
  wn.com/Louis_Essen
• 
  Marin Mersenne
  Marin Mersenne, Marin Mersennus or le Père Mersenne (8 September 1588 – 1 September 1648) was a French theologian, philosopher, mathematician and music theorist, often referred to as the "father of acoustics" (Bohn 1988:225). Mersenne was "the center of the world of science and mathematics during the first half of the 1600s."
  Marin Mersenne (pronounced Mehr-SENN) was born of peasant parents near Oizé, Maine (present day Sarthe, France). He was educated at Le Mans and at the Jesuit College of La Flèche. On 17 July 1611, he joined the Minim Friars, and, after studying theology and Hebrew in Paris received his full holy orders in 1613.
  
  wn.com/Marin_Mersenne
• 
  Persian people
  The Persian people are part of the Iranian peoples who speak the modern Persian language and closely akin Iranian dialects and languages. The origin of the ethnic Iranian/Persian peoples are traced to the Ancient Iranian peoples, who were part of the ancient Indo-Iranians. The synonymous usage of Iranian and Persian has persisted over the centuries although some modern Western sources use Iranic/Iranian as a wider term that includes the term Persian as well as related Iranian languages and ethnic groups. However, these terms have been used both synonymously as well as in a complementary fashion since ancient times; as the Ancient Iranian peoples such as the Old Persians, Medes, Bactrians, Parthians and Avesta peoples considered themselves to be part of the greater Iranian ethnic stock.
  The term Persian translates to "from or of Persis" which is a region north of the Persian Gulf located in Pars, Iran. It was from this region that Cyrus the Great, the founder of the Achaemenid empire, united all other Iranian empires (such as the Medes and the Elamites), and expanded the Persian cultural and social influences by incorporating the Babylonian empire, and the Lydian empire. Although not the first Iranian empire, the Achaemenid empire is the first Persian empire well recognized by Greek and Persian historians for its massive cultural, military and social influences going as far as Athens, Egypt, and Libya.
  
  wn.com/Persian_people
• 
  Ptolemy
  Claudius Ptolemy ( /ˈtɒləmi/; Greek: Κλαύδιος Πτολεμαῖος, Klaudios Ptolemaios; Latin: Claudius Ptolemaeus; c. AD 90 – c. AD 168), was a Greek-Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the Thebaid. This theory, proposed by Theodore Meliteniotes, could be correct, but it is late (ca. 1360) and unsupported. There is no reason to suppose that he ever lived anywhere else than Alexandria, where he died around AD 168.
  Ptolemy was the author of several scientific treatises, at least three of which were of continuing importance to later Islamic and European science. The first is the astronomical treatise now known as the Almagest (in Greek, Ἡ Μεγάλη Σύνταξις, "The Great Treatise", originally Μαθηματικὴ Σύνταξις, "Mathematical Treatise"). The second is the Geography, which is a thorough discussion of the geographic knowledge of the Greco-Roman world. The third is the astrological treatise known sometimes in Greek as the Apotelesmatika (Ἀποτελεσματικά), more commonly in Greek as the Tetrabiblos (Τετράβιβλος "Four books"), and in Latin as the Quadripartitum (or four books) in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day.
  
  wn.com/Ptolemy
• 
  Roger Bacon
  Roger Bacon, O.F.M. (c. 1214–1294), (scholastic accolade Doctor Mirabilis, meaning "wonderful teacher"), was an English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empirical methods. He is sometimes credited, mainly starting in the 19th century, as one of the earliest European advocates of the modern scientific method inspired by the works of Aristotle and later pseudo-Aristotelian works, like the works of Muslim scientist Alhazen. However, more recent reevaluations emphasize that he was essentially a medieval thinker, with much of his "experimental" knowledge obtained from books, in the scholastic tradition. A survey of the reception of Bacon's work over centuries found that it often reflects the concerns and controversies central to the receivers.
  Roger Bacon was born in Ilchester in Somerset, England, possibly in 1213 or 1214 at the Ilchester Friary. The only source for his date of birth is his statement in the Opus Tertium, written in 1267, that "forty years have passed since I first learned the alphabet". The 1214 birth date assumes he was not being literal, and may have meant 40 years had passed since he matriculated at Oxford at the age of 13. If he had been literal, his birth date was more likely to have been around 1220/1222. In the same passage he reports that for all but two of those forty years he had always been engaged in study. His family appears to have been well-off, but, during the stormy reign of Henry III of England, their property was despoiled and several members of the family were driven into exile.
  
  wn.com/Roger_Bacon
• 
  Tycho Brahe
  Tycho Brahe (14 December 1546 – 24 October 1601), born Tyge Ottesen Brahe, was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations. Coming from Scania, then part of Denmark, now part of modern-day Sweden, Tycho was well known in his lifetime as an astronomer and alchemist.
  In his De nova stella (On the new star) of 1573, he refuted the Aristotelian belief in an unchanging celestial realm. His precise measurements indicated that "new stars" (novae or also now known as supernovae), in particular that of 1572, lacked the parallax expected in sub-lunar phenomena, and were therefore not "atmospheric" tail-less comets as previously believed, but occurred above the atmosphere and moon. Using similar measurements he showed that comets were also not atmospheric phenomena, as previously thought, and must pass through the supposed "immutable" celestial spheres.
  Tycho Brahe was granted an estate on the island of Hven and the funding to build the Uraniborg, an early research institute, where he built large astronomical instruments and took many careful measurements, and later Stjerneborg, underground, when he discovered that his instruments in the former were not sufficiently steady. Something of an autocrat on the island he nevertheless founded manufactories such as paper-making to provide material for printing his results. After disagreements with the new Danish king in 1597, he was invited by the Bohemian king and Holy Roman emperor Rudolph II to Prague, where he became the official imperial astronomer. He built the new observatory at Benátky nad Jizerou. Here, from 1600 until his death in 1601, he was assisted by Johannes Kepler. Kepler later used Tycho's astronomical results to develop his own theories of astronomy.
  
  wn.com/Tycho_Brahe
• 
  William Markowitz
  William Markowitz (February 8, 1907, Vítkov, Austrian Silesia - October 10, 1998, Pompano Beach, Florida) was an American astronomer, principally known for his work on the standardization of time.
  His mother was visiting Melč, Vítkov in Austrian Silesia (now cs:Melč, Czech Republic) when William was born. The Polish family emigrated to the U.S. in 1910 and settled in Chicago.
  William earned his doctorate from the university in 1931, under W.D. MacMillan. He taught at Pennsylvania State College before joining the United States Naval Observatory in 1936, working under Paul Sollenberger and Gerald Clemence in the time service department.
  After having married Rosalyn Shulemson in 1943, Markowitz eventually became director of the department. He developed the ephemeris time scale, which had been adopted by the IAU in 1952 on a proposal formulated by Clemence in 1948, as an international time standard. He subsequently worked with Louis Essen in England to calibrate the newly developed atomic clocks in terms of the ephemeris second. The fundamental frequency of caesium atomic clocks, which they determined as 9,192,631,770 +/- 20 Hz, was used to define the second internationally since 1967. At the International Astronomical Union (IAU) meeting in Dublin in 1955, he had proposed the system of distinguishing between variants of Universal Time, as UT0 (UT as directly observed), UT1 (reduced to invariable meridian by correcting to remove effect of polar motion) and UT2 (further corrected to remove (extrapolated) seasonal variation in earth rotation rate), a system which remains in some use today.
  
  wn.com/William_Markowitz

Seconds Apart (2011)

Actors

• Orlando Jones
• Gary Entin
• Edmund Entin

Director

• Antonio Negret

• Rincón exquisito
• Palabras
• Rodamos
• Conocerte
• Nuevos secretos
• Todas las cosas
• En el viaje
• Dicen
• Para bien o para mal
• A las 10
• Más suerte
• Cómo sería

• Invisible
• Her Diary
• Horas De Humo
• Fortune Day
• Algo
• Nada Te Dirige
• Erased World
• Useless Junk
• Línea Imaginaria
• On an Island

• My Little Girl
• 17
• Sunday's Hit
• In My Life
• Whisper It
• You Are a Short Song
• My Game Is Over
• Surrender
• Watching the Moon

• Accident
• Behind the Pose
• The Red Bullet
• Different Levels
• Living in London
• Smiling to Camera
• Star Glasses
• Situation
• TV Programmes
• Sometimes
• Sweet Caffeine
• Great Failures

• timeline:
• 2012
• 2011
• 2010
• 2009
• 2008
• 2007
• 2006
• 2005
• 2004
• 2003
• 2002
• 2001

• timeline:
• 2012
• 2011
• 2010
• 2009
• 2008
• 2007
• 2006
• 2005
• 2004
• 2003
• 2002
• 2001