четверг, 20 марта 2025 г.

Greek concept

 

Greek concept

The modit]ve towards a rational understanding of nature began at least since the Archaic period in Greece (650–480 BCE) with the Pre-Socratic philosophers. The philosopher Thales of Miletus (7th and 6th centuries BCE), dubbed "the Father of Science" for refusing to accept various supernatural, religious or mythological explanations for natural phenomena, proclaimed that every event had a natural cause.[1] Thales also made advancements in 580 BCE by suggesting that water is the basic element, experimenting with the attraction between magnets and rubbed amber and formulating the first recorded cosmologies. Anaximander, developer of a proto-evolutionary theory, disputed Thales' ideas and proposed that rather than water, a substance called apeiron was the building block of all matter. Around 500 BCE, Heraclitus proposed that the only basic law governing the Universe was the principle of change and that nothing remains in the same state indefinitely. He, along with his contemporary Parmenides were among the first scholars to contemplate on the role of time in the universe, a key concept that is still an issue in modern physics.

Aristotle (384–322 BCE)

During the classical period in Greece (6th, 5th and 4th centuries BCE) and in Hellenistic timesnatural philosophy developed into a field of study. Aristotle (GreekἈριστοτέληςAristotélēs) (384–322 BCE), a student of Plato, promoted the concept that observation of physical phenomena could ultimately lead to the discovery of the natural laws governing them.[citation needed] Aristotle's writings cover physics, metaphysicspoetrytheatermusiclogicrhetoriclinguisticspoliticsgovernmentethicsbiology and zoology. He wrote the first work which refers to that line of study as "Physics" – in the 4th century BCE, Aristotle founded the system known as Aristotelian physics. He attempted to explain ideas such as motion (and gravity) with the theory of four elements. Aristotle believed that all matter was made of aether, or some combination of four elements: earth, water, air, and fire. According to Aristotle, these four terrestrial elements are capable of inter-transformation and move toward their natural place, so a stone falls downward toward the center of the cosmos, but flames rise upward toward the circumference. Eventually, Aristotelian physics became popular for many centuries in Europe, informing the scientific and scholastic developments of the Middle Ages. It remained the mainstream scientific paradigm in Europe until the time of Galileo Galilei and Isaac Newton.

Early in Classical Greece, knowledge that the Earth is spherical ("round") was common. Around 240 BCE, as the result of a seminal experimentEratosthenes (276–194 BCE) accurately estimated its circumference. In contrast to Aristotle's geocentric views, Aristarchus of Samos (GreekἈρίσταρχοςc. 310 – c. 230 BCE) presented an explicit argument for a heliocentric model of the Solar System, i.e. for placing the Sun, not the Earth, at its centre. Seleucus of Seleucia, a follower of Aristarchus' heliocentric theory, stated that the Earth rotated around its own axis, which, in turn, revolved around the Sun. Though the arguments he used were lost, Plutarch stated that Seleucus was the first to prove the heliocentric system through reasoning.

The ancient Greek mathematician Archimedes, developer of ideas regarding fluid mechanics and buoyancy.

In the 3rd century BCE, the Greek mathematician Archimedes of Syracuse GreekἈρχιμήδης (287–212 BCE) – generally considered to be the greatest mathematician of antiquity and one of the greatest of all time – laid the foundations of hydrostaticsstatics and calculated the underlying mathematics of the lever. A scientist of classical antiquity, Archimedes also developed elaborate systems of pulleys to move large objects with a minimum of effort. The Archimedes' screw underpins modern hydroengineering, and his machines of war helped to hold back the armies of Rome in the First Punic War. Archimedes even tore apart the arguments of Aristotle and his metaphysics, pointing out that it was impossible to separate mathematics and nature and proved it by converting mathematical theories into practical inventions. Furthermore, in his work On Floating Bodies, around 250 BCE, Archimedes developed the law of buoyancy, also known as Archimedes' principle. In mathematics, Archimedes used the method of exhaustion to calculate the area under the arc of a parabola with the summation of an infinite series, and gave a remarkably accurate approximation of pi. He also defined the spiral bearing his name, formulae for the volumes of surfaces of revolution and an ingenious system for expressing very large numbers. He also developed the principles of equilibrium states and centers of gravity, ideas that would influence future scholars like Galileo, and Newton.

Hipparchus (190–120 BCE), focusing on astronomy and mathematics, used sophisticated geometrical techniques to map the motion of the stars and planets, even predicting the times that Solar eclipses would happen. He added calculations of the distance of the Sun and Moon from the Earth, based upon his improvements to the observational instruments used at that time. Another of the early physicists was Ptolemy (90–168 CE) during the time of the Roman Empire. 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.

Much of the accumulated knowledge of the ancient world was lost. Even of the works of the many respectable thinkers, few fragments survive. Although he wrote at least fourteen books, almost nothing of Hipparchus' direct work survived. Of the 150 reputed Aristotelian works, only 30 exist, and some of those are "little more than lecture notes".

суббота, 15 марта 2025 г.

History of physics

 


History of physics

Physics is a branch of science in which the primary objects of study are matter and energy. These topics were discussed across many cultures in ancient times by philosophers, but they had no means to distinguish causes of natural phenomena from superstitions.

The Scientific Revolution of the 17th century, especially the discovery of the law of gravity, began a process of knowledge accumulation and specialization that gave rise to the field of physics.

Mathematical advances of the 18th century gave rise to classical mechanics, and the increased used of the experimental method led to new understanding of thermodynamics.

In the 19th century, the basic laws of electromagnetism and statistical mechanics were discovered.

At the beginning of the 20th century, physics was transformed by the discoveries of quantum mechanics, relativity, and atomic theory.

Physics today may be divided loosely into classical physics and modern physics.

Ancient history


Elements of what became physics were drawn primarily from the fields of astronomyoptics, and mechanics, which were methodologically united through the study of geometry. These mathematical disciplines began in antiquity with the Babylonians and with Hellenistic writers such as Archimedes and PtolemyAncient philosophy, meanwhile, included what was called "Physics".

среда, 5 февраля 2025 г.

The Milky Way

 

The Milky Way

The Milky Way is a large band of stars, dust and gas that make up our galaxy. It contains billions of stars. Our sun and the solar system is only one of them. The Milky Way is only one of billions of galaxies that make up our universe. It has a diameter of about 100,000 light years and is as old as the universe itself. The name probably refers to how we see our galaxy - a white blurry band that looks like spilled milk.

The Milky Way has the shape of a thin disk with six spiral arms coming out of a bulge in the center . This bulge consists of a cluster of large stars, gas and dust as well as a strong magnetic field. The whole galaxy rotates around this inner bar of stars. New stars are constantly formed around the spiral arms. Most of the stars in our galaxy are red dwarfs, cold stars that are much smaller than our sun.

 The galaxy gets flatter towards the edges. The center of the Milky Way consists of a black hole; an invisible object that has such a strong gravitational pull that not even light cannot escape. The galaxy is surrounded by a gigantic halo made up of old stars and gas that stretches hundreds of thousands of light years into the universe.

Our solar system is located on the inner edge of one of the spiral arms, about 30,000 light years from the centre. It completes one orbit around the centre about every 240 million years.

 Astronomer Edwin Hubble was the first to find out that the Milky Way is only one of many galaxies in our universe. The nearest is Andromeda, which is often referred to as our sister galaxy. It is estimated that in about 4 billion years the Milky Way and Andromeda will collide.

Words

  • astronomer = a scientist who studies the sky and the stars
  • bar = band
  • billion = a thousand million
  • blurry = unclear
  • bulge = a thick curved mass
  • cluster = very many
  • collide = crash
  • constantly = always
  • contain = is made up of
  • diameter = the distance from one end of a circle to the other
  • disk = round flat shape
  • dust = very small particles of dirt
  • dwarf = a creature that looks like a very small man
  • edge = border, rim
  • escape = get away
  • estimate = guess, think
  • gravitational pull = the force that pulls something towards it
  • halo = circle of light
  • invisible = something that cannot be seen
  • light years = the distance that light travels in one year ( about 6 000 000 000 000 miles)
  • located = exists, can be found
  • orbit = to move around an object in a circle
  • refer = is about
  • rotate = to go around
  • spill = when a liquid flows over the edge of a container by accident
  • spiral = to move in a curve that gets nearer to or farther from the center as it goes around
  • stretch = reach from one place to another
  • surrounded = around it

Lightning


Lightning 

 Lightning is a form of electricity that is set free during a storm. Energy is suddenly released in a cloud when charges are built up. Although lightning is most common in tropical and subtropical regions, it can happen wherever hot air mixes with cold air. Thunderstorms produce about 8 million lightning bolts a day.

For a long time lightning was a big mystery. Ancient people thought that god was punishing people by sending a bolt of lightning down to Earth.

 How lightning forms

Water droplets and ice crystals in a cloud have electric charges, positive and negative ones. Lightning happens when too many negative charges build up in a cloud and positive charges develop on the ground.

The particles want to meet and race towards each other. A flash of lightning is a sign of this meeting. Such a charge of light can be very hot, up to 20,000 degrees Celsius. It can be up to 5 km long. Large clouds produce more electric charges and eventually a very strong electrical current.

Lightning can also occur between two clouds or within a single cloud. In rare cases negative charges can form on the ground and lighting moves upwards, as is the case when a rocket starts.
Lightning strikes very quickly, several times within a second, but single bolts of lightning are impossible to see with a naked eye. A series of such bolts appear as a single flash.

Thunder accompanies lightning. It forms when electricity travels quickly through the air and starts vibrating. The hot air surrounding a bolt of lightning causes the air to expand, causing noise.

 Effects

Lightning can do damage to buildings, cars or other objects when it hits.  It can also kill or injure human beings. During a thunderstorm people should stay away from doors, windows and electrical devices.  You should also stay away from phones and wires because lightning can travel through them. When you’re in the open do not try to protect yourself by hiding under a tree.

You can protect your house or other buildings surrounding your home by installing a lightning rod on the roof. It attracts the lighting that would otherwise hit the building and leads it to the surface.

Lightning can also have positive effects. It produces nitrates and other compounds when it is created in the air. These nutrients fall down to Earth and enrich the soil for good farming.

Words

  • accompany = go with; to happen together with
  • although = while
  • ancient =  old
  • attract = pull towards itself
  • bolt =lightning that appears as a white line in the sky
  • charge = here: small amount of electricity 
  • common = often seen
  • damage = destroy
  • develop = grow
  • device = object, tool, machine
  • droplet = small drop
  • electrical current = flow of electricity
  • enrich = to make better
  • eventually = in the end
  • expand = become larger
  • flash = white burst
  • human being = person
  • injure = hurt
  • install = put in, set up
  • lightning rod = metal wire that is fixed to the top or side of a building  and is used to protect the it from lightning
  • nitrate = substance that has nitrogen and oxygen in it and is used to make plants grow better
  • nutrient = chemical or food that gives plants what they need to grow
  • occur = happen
  • otherwise  = or else
  • punish = to make someone suffer because they have done something wrong
  • race = move quickly
  • rare = not very often
  • release = set free
  • series = one after the other
  • several = many
  • sign = signal
  • soil = top layer of earth on which plants grow
  • suddenly = unexpectedly, all of a sudden
  • surface = the top part of something
  • surrounding = around
  • towards = in the direction of
  • wire = thin cable of metal that can carry electricity

Astronomy

 

Astronomy

Astronomy is about studying space, the universe, stars and the planets in our solar system. Astronomers are scientists who try to find answers to questions relating to our universe. They observe planets, faraway stars and galaxies as well as certain events that occur in space. They examine the structure of the universe and try to find out how it all began.

Ancient Astronomy

Astronomy has been around for thousands of years.  In ancient times, people observed the sun and the stars on a daily basis. They planted crops and held certain events relating to the movement of objects in the sky.

Ancient civilizations, like the Greeks and Romanshowever did not have the instruments that later generations had. They had to observe the skies and stars with their naked eye.  It helped them navigate the seas and guide them to other places.

They saw that stars were arranged in patterns that looked like humans or animals.
In ancient times, people thought that the Earth was the centre of the universe and that everything revolved around it. Towards the end of the Middle Ages some astronomers were not quite convinced about this  theory. In the early 16th century Nicolaus Copernicus, a Polish astronomer, was the first to show that in fact the sun was the centre of the solar system and planets revolved around it. Almost a century later Italian astronomer Galileo used the first telescope to observe space. His studies supported Copernicus’ theories. German mathematician Johannes Kepler proved that planets travel around the sun in elliptical pathsIsaac Newton used Kepler’s findings to explain how gravity worked.

 Modern astronomy

The discovery of the telescope changed the way scientists could observe space. While ancient people only were able to see objects near Earth, telescopes were able to find Uranus, Neptune and Pluto, the distant planets of our solar system.

Astronomers also found that an asteroid belt moves around the sun between the Earth and Mars. With the help of powerful telescopes, they were able to  map the surface of the moon and other planets in great detail.

Modern astronomy uses powerful telescopes on earth to see objects far away from our solar system. It also relies on images sent to earth from orbiting telescopes, like the Hubble Space Telescope, which has been in operation since 1990.

Unmanned spacecraft that land on the moon and other planets give astronomers large amounts of data and images that they can use for their work. Astronomers also study samples of rocks that spacecraft have brought back to Earth.

Today, astronomers use computers to simulate movements and events that may happen in space. For example, they can predict how close an asteroid can come to earth or when certain comets appear.

Astronomers measure distances in light years – how far light can travel in one year, which is about 6 trillion miles (9.4 trillion km). They have found out that our galaxy, the Milky Way, has a diameter of 100,000 light years. The nearest star is Proxima Centauri, about four light years away from Earth.

пятница, 13 декабря 2024 г.

Space Agencies Go For Jupiter and Saturn

 

Space Agencies Go For Jupiter and Saturn

 

NASA and the European Space Agency have decided to go ahead with an ambitious plan to send a probe to Jupiter and its icy moon Europa. A further project would involve the two agencies to send a spacecraft to Saturn’s moon Titan.

David Southwood, ESA’s Director of Science says that the joint venture is a wonderful new challenge and it will be a milestone of 21 st century space exploration. The Jupiter mission has been chosen to start because it is the more realistic project.

Scientists have been dreaming of visiting Europa for a long time. The icy moon may have underground water and researchers want to find out if such a satellite may be fit for life. It is surely one of the places in the solar system where life might have evolved some time ago.

The project calls for NASA to send an orbiter to Europa and ESA to send one to Jupiter’s moon Ganymede. Both spacecraft would be launched in 2020, but from two separate launch sites. They would reach Jupiter by 2026 and examine the moons for the following three years. Although the two spacecraft would observe Europa from different positions only the NASA probe would spend time in Europa’s orbit.

The moon is said to have a strong radiation field and orbiting it would only be possible for a few months. NASA plans to use special equipment to protect its probe. The two probes would end their mission by crashing into the moons they are orbiting around.

British scientists and engineers will play key roles in the joint mission. A consortium is planning to prepare probes with instruments that would be dropped onto Europa’s surfaceThus, it could determine temperatures under the surface or locate magnetic and radiation fields.

 

Galileo Galilei

Galileo is often called the founder of modern science. He made many discoveries in astronomy and physics and he built telescopes to study space.

Galileo Galilei was born in Pisa, Italy in 1564. His father sent him to the university to study medicine, but young Galileo was more interested in science and mathematics.

Galileo made one of his greatest discoveries as he sat in a cathedral of Pisa. As he watched a chandelier swing back and forth he noticed that longer and shorter swings took the same time. This discovery became known as the law of the pendulum. These and other important discoveries made him so well-known that Galileo became a professor at the University of Pisa.

 Galileo often questioned scientific facts of his age. For a long time people thought that heavier objects fall to Earth faster than lighter ones. By dropping objects of the same size but different weights from the Leaning Tower of Pisa Galileo showed that this wasn’t true.

 In 1609 Galileo constructed his first telescope. He used it to observe the stars and the planets. He saw things that nobody had ever seen before. Galileo discovered that the moon’s surface was not smooth and flat, like everyone thought, but had a rough surface and was full of craters.

In January 1610 Galileo discovered 4 moons revolving around the Jupiter. They were named after him, the Galilean moons. These observations proved that not the Earth was the centre of the solar system, but the sun. It was a discovery that Copernicus had made 60 years earlier.

The Roman Catholic Church did not always like what Galileo taught. It still believed that the Earth was the centre of the universe and everything revolved around it. The church ordered him not to teach such ideas any more.

In 1633 Galileo was brought before the Inquisition, the Church’s court. It sentenced him to life in prison because of his teachings. Galileo was put under house arrest because he was old and not so healthy any more. He spent the last years of his life in Florence, where he continued to work on his theories and even published a final book. He became blind and died in 1642.

In 1992 Pope John Paul II published a document that said the Church made a mistake by condemning Galileo.