Balloonist theory: Early theory of neuroscience

Balloonist theory was a theory of muscle contraction centered on the idea of explaining muscle movement by asserting that muscles contract by inflating with air or fluid.

The Greek physician Galen believed that muscles contracted due to a fluid flowing into them, and for 1500 years afterward, it was believed that nerves were hollow and that they carried fluid. Galen lived from about A.D.130 to 200.

It was the 17th century philosopher, scientist and mathematician, René Descartes, who was explain various aspects of physiology such as the reflex arc, proposed that "animal spirits" flowed into muscle and were responsible for their contraction. In extending his speculations beyond the notions of his predecessors, Descartes relied extensively upon mathematical and mechanical models. He postulated that the heart supplied "animal spirits" to the nerves, which conveyed the spirits to the muscles, very much as water is conducted through pipes.

In 1667, Thomas Willis, a London physician, proposed that muscles may expand by the reaction of animal spirits with vital spirits. Although his speculations about the anatomical sites of reflection, memory, and phantasy had little enduring scientific impact, his investigations did contribute important information about the blood supply to the brain. The ring of blood ves-sels which he described at the base of the brain continues to bear his name (the circleof Willis) and still is an important landmarkof brain anatomy.

The end of the "balloonist" theories of nerve-muscle activities came, after Jan Swammerdam, a Dutch anatomist famous for working with insects, struck the first important blow against the balloonist theory. Jan Swammerdam, in the 1667, performed a most elegant series of experiments on this point, and proved that contracting muscles were not swollen by any influx of fluids from nerves.

Francis Glisson (1597-1677) disproved balloonist theories of nerve function by submerging a man's arm in water and measuring the displacement of water when the muscles were con-tracted. Because no change in water level could be observed, Glisson concluded that muscle contraction was not the result of fluid flowing into the muscle as was commonly thought.

The invention of the microscope allowed preparations of nerves to be viewed at high magnification, showing that they are not hollow.

In 1791, Luigi Galvani learned that frogs' muscles could be made to move by the application of electricity. In 1848, Emil du Bois-Reymond was the first to demonstrate that the nervous effect was an electrical phenomenon and that a wave of electrical negativity, an action potential, passes down the nerve.

Balloonist theory: Early theory of neuroscience

History of rainbow

Rainbow as a scientific problem appears to have been treated first by Aristotle in the history of optics.

As long ago as in the 3rd-2nd centuries BC, Alexander of Aphrodisias tried to describe the rainbow as a phenomenon involving light and colour; he is regarded as the discoverer of the darker region between the primary and the secondary rainbows.

Aristotle (383-322 BC) was the first one to give a complete description of the optical phenomenon, in Book III of his Meteorology. He proposed that the rainbow is actually an unusual kind of reflection of sunlight from clouds. The light is reflected at a fixed angle. giving rise to a circular cone of "rainbow rays. " In the opinion of Aristotle the rainbow comes into existence in a hemisphere, the centre of which is the observer’s eye and the base of which is the horizontal line,

Ibn al-Haytham (965-1039) treated the formation of rainbow in an article called Maqala fi al-Hala wa qaws quzah. In this article he explained the formation of rainbow as an image, which forms at a concave mirror. If the rays of light coming from a farther light source reflect to any point on axis of the concave mirror, they form concentric circles in that point. When it is supposed that the sun as a farther light source, the eye of viewer as a point on the axis of mirror and a cloud as a reflecting surface, then it can be observed the concentric circles are forming on the axis.

The Persian astronomer and mathematician Qutb Al-Dı ̄n al-Shira ̄zı ̄ (1236–1311) and his pupil al-Fa ̄risı ̄, also known as Kama ̄l al-Dı ̄n (1260–1320), tried to give a first mathematical explanation of the rainbow, which was quite accurate for its age, since it was based on the phenomenon of refraction as described in the Book of Optics by Alhazen.

The angle formed by the rainbow rays and the incident sunlight was first measured in 1266 by Roger Bacon. He measured an angle of about 42 degrees; the secondary bow is about eight degrees higher in the sky.

In 1304 the German monk Theodoric of Freiberg rejected Aristot­le's hypothesis that the rainbow results from collective reflection by the rain­drops in a cloud. He suggested instead that each drop is individually capable of producing a rainbow. Moreover, he test­ed this conjecture in experiments with a magnified raindrop: a spherical flask filled with water. He was able to trace the path followed by the light rays that make up the rainbow.

Kama ̄l al-Dı ̄n’s experiments were repeated by Descartes (1596-1650) when he got interested in rainbow. He made some experiments in the light of the sun, with glassy sphere full of water. Standing on foot and directing his back to the sun, he watched through a hole in the glassy sphere, shaking it upward and downward, he finally discovered brightness at the bottom of the sphere. Kama ̄l al-Dı ̄n made similar experiments and obtained the same results as Descartes, many years before him.

In the 17thcentury the rainbow became a strictly physical phenomenon, the object of rigorous investigations according to the law of reflection and refraction.

History of rainbow

Theory of geomorphology

Geomorphology, the scientific study of the origin and evolution of land surface processes and morphology, seeks to understand the migration of materials and energy transforming/ dissipating processes at the interfaces of the atmosphere, lithosphere and hydrosphere.

The word geomorphology, which means literally ‘to write about the shape or form of the earth’, first appeared in 1858 in the German literature written by Luamann.

The term was referred to in 1866 by Emmanuel de Margerie as ‘la geomorpholgie’; it first appeared in English in 1888 and was used at the International Geological Congress in 1891 in papers by McGee and Powell.

The first theory of geomorphology was arguably devised by the Chinese scientist and statesman Shen Kuo (1031-1095). He observed marine fossil shells in a geological stratum of mountain hundreds of miles from the Pacific Ocean.

He formulates the theory of geomorphology, including deposition, uplift, erosion and the role of climate change, in studies of the Taihang Mountains of China.

James Hutton (1726-97), the founder of modern geology published Theory of the Earth; or, An Investigation of the Laws Observable in the Composition, Dissolution and Restoration of Land Upon the Globe. He was also regarded as a father of geomorphology because of his theory of the Earth illustrated the importance of denudation in the development oif the Earth’s surface.

The quantitative revolution in geomorphology during the late 1950s and middle 1960s greatly enhanced development of the discipline.
Theory of geomorphology

Theory of planetary motion

For 2,000 years, astronomers placed the earth at the center of the universe and assumed that all heavenly bodies moved in perfect circles around it. Copernicus discovered that the sun lay at the center of the solar system, but still assumed that all planets traveled in perfect circles.

Copernicus put forth the idea of the heliocentric universe in his book De Revolutionibus Orbium Coelestium. Howevr, he was not the forts person to arote about it. The idea can be traced back almost two thousand years earlier to the Greek mathematician and philosopher Aristarchus of Samos (310-230 BC).

Johannes Kepler was born in Southern Germany in 1571, 28 years after the release of Copernicus’s discovery.

Kepler used Copernicus’s model as the foundation for his laws of planetary motion.  Kepler accepted Copernicus’s heliocentric idea, but he also found parts of De Revolutionibus troubling. Kepler believed that earth and other know planets revolved around the sun, called the heliocentric model.

Elliptical orbits became Kepler’s first law, Kepler then added his Second Law each planet’s speed altered as a function of its distance from the sun. As a planet flew closer, it flew faster.

Kepler published his discoveries in 1609 and then spent the next 18 years calculating detailed tables of planetary motion and position for all six known planets.
Theory of planetary motion

Gravitational theory by Einstein

Gravitation is commonly understood as the force of attraction between objects by virtue of their mass. In 1687, Newton published The Philosophiae Naturalist Principia Mathematica in which he prop0soed his law of gravitation.

Richer Cassini and Piccard had found evidence in 1672 that the earth had an equatorial bulge. Newton was able to use his new gravitational theory to calculate a theoretical value for this oblateness of 1/230. He then considered the gravitation attraction of the moon and sun on the oblate earth and calculated that the earth’s spin axis should process at baa rate do about 50’’.0 per annum.

According to this law the gravitational force of attraction between two bodies is always proportional to their masses and inversely proportional to the square of their distance apart, and it acts instantaneously through infinite distance.

A more widely applicable theory of gravitation is Albert Einstein’s general theory of relativity. According to Einstein’s general theory of relativity published in 1913, gravitation is not a forced of attraction but rather the force required to prevent the natural motion of matter, which is to follow a geodesic in space time.

Einstein introduced into gravitational theory a type of mathematics that was then unfamiliar to most physicists thus presenting an initial impression of incomprehension. In his theory Einstein used the space-time continuum introduced by Hermann Minskowski in 1907, the non-Eucladian geometry developed by Bernhard Riemann in 1854 and the tensor calculus published by Gregorio Ricci in 1887.

The first indirect experimental proof of gravitational waves was provided in 1984 by Weisberg and Taylor. By studying the pulsar 1913+16, they showed that the period of the pulsar around its companion star decreased exactly as predicted by the Einstein equation.

In 1969, Joseph Weber, a physicist at the University of Maryland, claimed to have detected gravitational waves using a six-foot-long aluminum cylinder as an antenna. In Feb 2016, a team of scientists at the Laser Interferometer Gravitational Wave Observatory (LIGO) announced they had detected agravitational waves resulting from the collision of two black holes some 1.3 billion years ago.

Scientists say that some 1.4 billion years ago two black holes - one the size of 36 suns and the other the size of 29- circled each other in a distant galaxy before finally colliding.

The collision of the two black holes—about 29 and 36 times more massive than the sun, respectively—produced a gigantic amount of energy in a fraction of a second, the equivalent of about 50 times the power of the entire visible universe. This energy, in the form of gravitational waves, is still spreading outwards today.
Gravitational theory by Einstein

Theory of optics by Ibn al-Haytham

The Optics of Ibn al-Haytham consists of seven books. It deals with the theory of vision; theory of perception: visual deception; the laws of reflection, mathematical problems concerning refection in mirrors; errors of vision due to reflection; and refraction.

Ibn al-Haytham’s object in the Book of Optics is: to achieve a synthesis between the geometrical optics of Ptolemy and Euclid and the traditions of natural philosophy, including the Aristotelian tradition.

Book of Optics was a real science textbook, with detailed descriptions of experiment, including the apparatus and the way it was set up, the measurements taken and the results.

These were then used to justify his theories which he developed using mathematical models.

Kitāb al-Manāẓir

Ibn al-Haytham rejects the Euclidean and Ptolemaic doctrine of a ray stemming out from the eye, called a visual ray, in order to defend the intromissionist theory of visible forms.

Ibn a-Haytham says that ‘forms’ of light propagate from any point on the luminous object in all directions. Ibn al-Haytham proves that the incident and reflected ray are coplanar with the normal to the mirror through the point of refection and make equal angles with the normal.

In the Book of Optics he devotes the first three chapters to the foundations of this theory. In the three following chapters, he deals with catoptrics.

The Book of Optics was translated into Latin around 1200, and the first printed edition by F. Risner appeared in 1572.

The work was studied by many notable European scientists, such as Witelo, Roger Bacon, Leonardo da Vinci, Kepler and Descartes. Ibn al-Haytham was aware of the structure of the eye from the view point of a physician as well as a physicist.

Equally importantly, later Islamic scholars would make great used of his work and extend it further, such as the Persian al-Shirazi and al-Farisi in the thirteenth century ,the latter using it for the very first correct mathematical, explanation of the rainbow.

Many of anatomical names of the various parts of the eye that are used today are translations from the names given by Ibn la-Haytham in his Book of Optics.
Theory of optics by Ibn al-Haytham

What is a Black Hole in space?

Term coined by John A. Wheeler for an object so compact that nothing, not even light, can escape its gravitational attraction.

Although the discussions of the capture of light by massive objects can be dated to John Mitchell and Pierre Simon Laplace in the eighteenth century, a proper understanding lies in the realms of general relativity theory.

Karl Schwarzschild calculated the boundary radius or event horizon, of such a theoretical (nonrotating) body to be about 3 km for a body of one solar mass.

Interior to the event horizon relativity theory suggests that any matter collapse into an infinitesimally small volume or singularity.

In 1963, a solution for a rotating object was provided by Robert P. Kerr. Stephen W. Hawking in the 1970s applied quantum mechanical concepts to the theory of black holes to show that they may not exist forever but can radiate energy.

To address the physical origin for black holes, J. Robert Oppenheimer and Hartman Snyder in 1939 first considered the collapse of a star.

Modern astronomy inquiry identifies two observational classes or black holes candidates, stellar black holes in X-ray binary systems and massive black holes on the nuclei of galaxies.

A dozen or more black hole candidates are known, including Cygnus X-1 and ScorpionX-1. The second category, a few million to a few billion solar masses, is postulated as the central engine responsible for a wide range of energetic phenomena (radio, X-ray, and gamma-ray emission, jets and others) associated with the nuclei of some galaxies.

Such active galactic nuclei objects include Seyfert galaxies, radio lobe galaxies, and quasars. Massive black holes also may be present in the centers of some nonactive galaxies.
What is a Black Hole in space?

Seleucus of Seleucia: Discovery of tides being caused by the moon

The connection among tides, moon and sun has been known since ancient times. Pytheus of Marseilles was the first of the Greek astronomers to correctly related and record the movement of the tides with the phases of the moon. He sailed to northwestern Europe and circumnavigated Great Britain in 325 BC.

Along documenting polar ice and the midnight sun that does not set in the far north on the summer Solstice, Pytheus also reported that the moon caused the tides.

The link between tides and the moon was first theorized by Seleucus of Seleucia in the 2nd century. He speculated that the tides were caused by the motions of the moon.

Seleucus of Seleucia, the Babylonian astronomer wrote that the rising and falling of tides were the result of the attractions of the moon and that the height of the tides depends on the location of the moon relative to the sun.

Born in the Babylonian town of Seleucia, he is today primarily remembered as the only known supporter of Aristarchus's heliocentric theory, maintaining that it accurately described the physical structure of the universe.

According to Plutarch, Seleucus was the first to prove the heliocentric system through reasoning, but it is not known what arguments he used. Seleucus’ arguments for a heliocentric theory were probably related to the phenomenon of tides.
Seleucus of Seleucia: Discovery of tides being caused by the moon

James Clerk Maxwell and Maxwell’s equations

The greatest single advance in theoretical physics in the 1800s was the formulation of what are now known as Maxwell’s equations, named after the nineteenth century physicist James Clerk Maxwell.

James Clerk Maxwell (13 June 1831 – 5 November 1879) was born in Edinburgh, Scotland and was educated at his country home until he was 78 years old, when his mother died.

He attended the University of Edinburgh at the age 16, and at age 19, he went Peterhouse Cambridge but moved trinity to obtain a fellowship.

In 1856, he moved to Marischal College in Aberdeen to be near his father. In 1860, Maxwell was appointed to the chair of Natural Philosophy at King’s College in London, where he did his most productive work and from 1871 until his death.

The eponymous equations were actually developed by several physicists but it was Maxwell who determined the importance of these four equations from the many in the field of theoretical physics that completely define the entire filed of electromagnetics.

The equations first appeared in the Treatise on Electricity and Magnetism in 1873. He wrote this book was essentially to explain Faraday’s idea into a mathematical and therefore more universal form.

The publication of the Treatise on Electricity and Magnetism was the turning point in electromagnetics. It was for the first time since Oersted’s discovery of the link between electricity and magnetism that this link extended to the generation and propagation waves.

Maxwell’s four equations govern all the characteristics of magnetic and electric field. Individually there are titled:
*Ampere’s law
*Faraday’s law of induction
*Gauss; electric law
*Gauss’ magnetic

These equations are assumed to be one of the greatest achievements of the 19th century mathematics.
James Clerk Maxwell and Maxwell’s equations

Theory of big-bang

Big-Bang theory is the theory of the creation of the universe. The Big-Bang theory states that the expanding universe originated 10-20 billion years ago in a single explosive event in which the entire universe suddenly exploded out of nothing, reaching a pea sized super condensed state.

Georges Lemaître first proposed what became the Big-Bang theory in 1927 after he realized how neatly this fitted the nonstatic models of general relativity and formulated the theory of t expanding universe.

Edwin Powell Hubble’s discovery of the galactic red shift in 1929 was the significant development. It indicated that all galaxies were receding from each other as part of an expanding universe. The color change happens when objects are moving away, making lightwaves stretch out and change color.

The more distant the galaxies are the faster they are rushing away.

Also in 1920s, George Gamow worked with a group of scientists and suggested that elements heavier than hydrogen, specifically helium and lithium, could be produced in thermonuclear reactions during the Big-Bang.

In 1948, Gamow and his student Ralph Alpher wrote a paper on ‘The Origin of Chemical Elements’ one of many contributions to the Big-Bang theory that Gamow made and a key step to the modern understanding of nucleosynthesis.

More evidence of the Big-Bang came in the 1960s, when astronomers detected faint microwave radiation coming from every point in the sky.
Theory of big-bang

Discovery of plate tectonics

The word tectonics comes from the Greek root ‘to build’. Plate tectonics describes how the outermost layer of the Earth is made up of a number of large chunks called ‘plates’. Because of forces inside the planet, these plates are in constant motion.

As they move, they continuously change the size and the shape of the oceans and continents.  Before the advent of plate tectonics, however, some people already believed that the present –day continents were the fragmented pieces of pre-existing larger landmasses or supercontinents.

The sixth century BC, Greek philosopher Thales suggested that the world floating on water, which accounted for the new springs that often spurt water and mud during and after an earthquake.

In 1596 the Dutch mapmaker Abraham Ortelius commented in his book that it looked as of South American and Africa had once been joined were later torn apart.

In the early part of the 1700s, most of the people who studied the Earth believed that the planet had changed very little over time.

Rene Descartes French philosopher and naturalist in his ‘Principia philosophiae’ (144) proposed that Earth contains a core with a liquid similar to the sun and wrapped by layers of rock, metal, water and air.

In 1785, James Hutton, Scottish doctor presented his idea to the Royal Society of Edinburgh. He proposed the theory of uniformitarianism, that all of the geologic features people see in ancient rocks can be explained by processes that can be observed in action today. It means the present is the key to the past.

In 1795, he published his findings in a two-volume book titled Theory of the Earth in which he provided dozens of examples to support his idea.

In 1912, 32 year old German meteorologist named Alfred Lothar Wegener contented that, around 200 million years ago the supercontinent Pangaea began to split apart.

Alexander Du Toit, Professor of Geology at Johannesburg University and one of Wegener’s staunchest supporters, proposed that Pangaea first broke into two large continental landmasses, Laurasia in the northern hemisphere and Gondwanaland in the southern hemisphere.

In 1967 William Jason Morgan and McKenzie proposed the broad outline for the theory of plate tectonic. While many unanswered questions remain, the theory of plate tectonics has become a cornerstone of modern geology.
Discovery of plate tectonics

Einstein Theory of Relativity

Einstein Theory of Relativity
In 1905 Einstein suggested that the new source of energy was none other than matter itself. The route by which he reached this conclusion deserves to be traced. Early in 1905 Einstein published his great paper “On the Electrodynamics of Moving Bodies’” which laid the a foundations of what came to be called the special theory of relativity.

The cardinal notion of the special theory is that light always travels at the same speed regardless of the speed of its source. If you toss a pebble forward from a moving automobile, then the speed or the pebble equals the speed of the automobile plus the speed with which the pebble was thrown. But with light situation is different. If you turn on the headlights of a speeding car, the velocity of the light from the headlights relative to the ground does not consist of the speed of the light plus the speed of the car. According to the special theory of relativity, the speed of the light from the moving headlight is exactly the same as it would have been if the car had not been moving at all. This simple idea that the speed of light is constant relative to very (un-accelerated) frame of reference changed physics and changed the world.

In late 1905 Einstein published three page meditation on the relationship between the mass of an object and energy contained in it. He reasoned that if the expenditure of energy needed to accelerate an object resulted in an increase in the mass of an object, then a decrease in velocity must produce a decrease in the mass of an object. The exact mathematical relationship between the mass of an object and the energy it contained flowed directly from the equations of the special theory, and was expressed in the famous formula:

E=mc2

that is, that the energy of a body is proportional to the mass of the body multiplied by the square of the speed of light. In 1908 physics and chemistry joined hands when Max Planck took note of Einstein’s equation and suggested that the phenomenon of radioactivity could be explained as the direct transformation of matter into energy.

In the years immediately following Einstein’s proposal, physicist and journalist amused themselves with calculations that a teaspoon of matter contained enough energy to power an ocean liner around the world. But even in the relatively pacific years before World War 1 the military implications of radioactivity and atomic energy did not go unnoticed.
Einstein Theory of Relativity

History of Quantum Mechanics

History of Quantum Mechanics
Quantum mechanics is the study of mechanical systems whose dimensions are close to the atomic scale, such as molecules, atoms, electrons, protons and other subatomic particles. Quantum mechanics is a most intriguing theory, the empirical success of which is as great as its departure from the basic intuitions of previous theories.

It is a fundamental branch of physics with wide applications. The foundations of quantum mechanics were established during the first half of the twentieth century by Werner Heisenberg, Max Planck, Louis de Broglie, Albert Einstein, Niels Bohr, Erwin Schrödinger, Max Born, John von Neumann, Paul Dirac, Wolfgang Pauli and others.

The history of quantum mechanics began essentially with the 1838 discovery of cathode rays by Michael Faraday, the 1859 statement of the black body radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig Boltzmann that the energy states of a physical system could be discrete, and the 1900 quantum hypothesis by Max Planck that any energy is radiated and absorbed in quantities.

According to the theorem proved by Gustav Kirchhoff in 1859 on the basis of the second principle of thermodynamics, the blackbody spectrum has a very remarkable property: It is a universal function of temperature only. In the 1877, Ludwig Boltzmann and Willy Wien restricted the form of this function by combining electromagnetism and thermodynamics. In the 1890s, spectroscopists working at Berlin measured it with the aim of determining an absolute standard for high temperature measurement. At the same time, the Berlin theorist Max Planck attempted a complete theoretical determination of the blackbody spectrum.

In 1905, Einstein computed the entropy of dilute thermal radiation from the high frequency limit of Planck’s law.

In 1913, Niels Bohr emphasized that mathematical symbols from classical mechanics permitted visualization of the atom as a minuscule Copernican system. Although suitably quantized laws of classical mechanics are used to calculate the electron’s allowed orbits, or stationary states, classical mechanics can neither depict nor describe the electron in transit.

In 1932 von Neumann put quantum theory on a firm theoretical basis. Some of the earlier work had lacked mathematical rigour, but von Neumann put the whole theory into the setting of operator algebra.

In 1933 Fermi develops a successful quantum field theory of beta decay. It describes how neutrons spontaneously change into protons and emit electrons and neutrinos.
History of Quantum Mechanics

Modern History of Artificial Intelligence

Modern History of Artificial Intelligence
Intelligence is the computational part of the ability to achieve goals in the world. Artificial intelligence can be defined as the study and design of intelligent agents, where an intelligent agent is a system that perceives its environment and take actions which maximize its chances of success.

Scientists began their research in artificial intelligence based on discoveries in neurology, mathematical theory, cybernetics and new invention in computer which based on mathematical reasoning.

In the 17th century, Descartes gave advent to more advanced thinking when he proposed the idea that animals are, in theory, nothing more than complex machine. Thomas Hobbes wrote in his famous Leviathan, which basically translates to “reason is nothing more than reckoning.” The idea that reasoning in human beings can be simplified into algebraic calculations was further discussed by Gottfried Leibniz, who coined the term characteristica universalis or universal language of reasoning.

The true driving factor of Artificial Intelligence came in the 1940’s with the creation of the electronic computer. Advancements in computer theory and computer science led to advancements in Artificial Intelligence as well. Since machines could now begin to manipulate numbers and symbols, this manipulation was thought to somehow be the basics of human thought. Princeton’s Walter Pitts and Warren McCulloch began work on the neural network, which attempted to give a mathematical description of the human brain.

In 1956 John MacCarthy from MIT coined the term ‘artificial intelligence’ as the topic of at Dartmouth Conference. He then invented the Lisp language in 1958. Dartmouth Conference was held at Dartmouth College in summer of 1956. Those who attended would become the leaders of artificial intelligence for many decades.

Within seven years after the conference, artificial intelligent began to pick up momentum. The ideas formed before were re-examined and further research was placed. In 1961, James Slagle in his PhD dissertation at MIT wrote the first symbolic integration program, SAINT which can solved calculus problems. In 1964, Danny Bobrow from MIT shows that computers can understand natural language enough to solve algebra world programs

In 1980 First National Conference of the American Association of Artificial Intelligence held at Stanford.

In early 1990s, The National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign develop and release the first widely used web browser, called Mosaic. The military put Artificial Intelligence based hardware to the test of war during Desert Storm. Artificial Intelligence-based technologies were used in missile systems, heads-up-displays, and other advancements. Artificial Intelligence has also made the transition to the home. With the popularity of the Artificial Intelligence computer growing, the interest of the public has also grown. Applications for the Apple Macintosh and IBM compatible computer, such as voice and character recognition have become available.

Late 1990’s, web crawls and other artificial intelligence information extraction programs become essential in widespread use of the World Wide Web.
Modern History of Artificial Intelligence

Black Hole

Black holes are objects so dense that not even light can escape their gravity, and since nothing can travel faster than light, nothing can escape from inside a black hole. On the other hand, a black hole exerts the same force on something far away from it as any other object of the same mass would. For example, if our Sun was magically crushed until it was about 1 mile in size, it would become a black hole, but the Earth would remain in its same orbit.

John Michell, a British geologist and astronomer, designed the experiment made by Henry Cavendish to measure the mass of the earth. Cavendish published the results of the experiment in 1798.

In 1783 Michell published his work, that showed that a star, that has the same density of the sun, but 500 time as big, would have such a gravity, that "All light emitted from such a body would be made to return towards it". He said we wouldn't be able to see such a body, but we sure will feel its gravitational pull.

Pierre-Simon Laplace, got to the same conclusion in 1795, and explained it by saying that "It is therefore possible that the greatest luminous bodies in the universe are on this very account invisible". Michell took to account a body that has the density of the sun, which equals to the density of water, while Laplace took to account a body that has the density of the earth, which is 5.5 more dense that water. To such bodies, there was invented in 1967 the name "Black-Holes"- a black hole in Space-Time. But it seems that over the years Laplace thought of this as a crazy idea, and he didn't work on this subject any more (over the 19th century more and more people believed the wave theory, and not the particle theory).

The people who believed light was composed of only small particles, compared it to a cannon shell, and said that if a cannon shell was pulled after some time to the earth, so would the light. But this comparison isn't completely true, because a cannon shell was also slowed down, while the light's speed is stable.

The first really main theory that dealt with gravity's effect on light was Einstein's General Theory of Relativity in 1905. Even then, it took time until it was used to see the effect of big stars on light.

The Indian research-student, Subrahmanyan Chandrasekhar, based his calculations on the life cycle of a star, while sailing to study in Cambridge with Arthur Eddington, an expert for the General Theory of Relativity, as his professor. He tried to calculate how massive a star can be, and still be in a stable condition, in spite of its gravitational pull, after the star has cooled down.
Black Hole