Everything is made up of matter. Matter is anything that takes up space and has mass. Anything that is material is made of matter – in fact both words come from the same Latin root meaning «stuff». Matter is made up of molecules, and molecules are made up of atoms.
About 2400 years ago, a Greek philosopher named Democritus (460-370 B.C.) thought a lot about what things were made of. One day while slicing an apple, he wondered how small he could slice it. He figured that everything that could be touched could be divided again and again until there was a piece left that was so small it couldn’t be cut. It turns out that he had the right idea, and that smallest piece we now know as the atom. The word atom comes from an ancient Greek word that means «uncuttable». Democritus could not see an atom (as we can today), but he had figured out something very important. His atom is what we talk about today as an element. In the mid-17th century, scientists began to prove the existence of specific elements, or pure substances that couldn’t be «cut» into other pieces. This led scientists to discover the elements and atoms that make up all matter. At the beginning of the 20th century, scientists found that Democritus’ atom actually could be cut into smaller pieces, called sub-atomic particles.
The parts of the atom are nucleus, electron, proton and neutron. The nucleus is at the center of the atom. It is made up of protons and neutrons. Moving around outside of the nucleus are the electrons. In 1915 a scientist named Niels Bohr proposed a model of the atom that illustrates the atomic structure, called the planetary model or the Bohr model. Proton comes from the Greek word for «first». Protons have a positive charge. Typically, positively charged particles would repel each other, but they are held together in the nucleus with a force called the strong atomic force. This is the strongest force in the universe. The other part of the nucleus is the neutron. Neutrons are about the same size as protons. The word «neutron» comes from the Latin word for «neutral». The neutron has no charge – it is neutral. The third particle of an atom is the electron. Electrons are much smaller than the protons or the neutrons (almost 2000 times smaller). It is easy to illustrate them orbiting around the nucleus using the Bohr model, although they actually move in a cloud. Electrons are negative. Protons and neutrons are both composed of other particles called quarks and gluons. Protons contain two «up» quarks and one «down» quark while neutrons contain one «up» quark and two «down» quarks. The gluons are responsible for binding the quarks to one another. (From www.wikipedia.org )
THE THEORY OF RELATIVITY
« When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity».
|according to – в соответствии с, согласно advance (N) – успех, достижение contradictory (N) – противоречащий contraction ( N ) – сокращение consequence ( N ) – следствие, вывод, заключение curve ( V ) – гнуть, изгибать; ( N ) кривая curvature ( N ) – кривизна, изгиб, искривление disagree ( V ) – не совпадать, расходиться encompass (V) – окружать, заключать equation ( N ) – уравнение, равенство exert ( V ) – приводить в действие, оказывать давление, влиять expand ( V ) – расширять inertial (Adj) – инерционный incompatible (Adj) - несовместимый increase ( V ) – увеличиваться instead of – вместо, взамен observer ( N) – наблюдатель postulate ( N ) – аксиома, постулат precess ( V ) – предварять, предшествовать propose ( V ) – предлагать, предполагать||regardless of – не обращая внимание, не взирая на shape ( N ) – форма, образ, модель simultaneity – одновременность slow down ( V ) – замедлять source ( N ) – источник space ( V ) – пространство, расстояние (между двумя объектами) spacetime – пространство-время suck up ( V ) – всасывать, поглощать the Special Theory of Relativity – специальная теория относительности the General Theory of Relativity – общая теория относительности time dilation – растяжение времени transmutable ( Adj ) – изменяемый, превращаемый uniform ( Adj ) – равномерный, постоянный upshot ( N ) – развязка, результат vacuum ( N ) – безвоздушное пространство, пустота well (N) – колодец, скважина with respect to – что касается|
Task 1. Discuss with a partner.
1. Do you agree or disagree with the quotation above?
2. What is relativity? Who introduced the theory of relativity?
Task 2. Scan the text « The Theory of Relativity » and match the information below with the years.
|a) Introducing the Special Theory of Relativity by Einstein||1907-1915|
|b) The period of Einstein’s life||1879-1955|
|c) Developing the General Theory of Relativity||1905|
The Theory of Relativity
The Theory of Relativity, proposed by the Jewish physicist Albert Einstein (1879-1955) in the early part of the 20th century, is one of the most significant scientific advances of our time. The Theory of Relativity, or simply relativity, generally encompasses two theories of Albert Einstein: Special Relativity and General Relativity.
Special Relativity is a theory of the structure of spacetime. It was introduced in Einstein's 1905 paper «On the Electrodynamics of Moving Bodies». Special Relativity is based on two postulates which are contradictory in classical mechanics: The laws of physics are the same for all observers in uniform motion relative to one another (principle of relativity). The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the light.
Some of the consequences of Special Relativity are:
- Relativity of simultaneity: Two events, simultaneous for one observer, may not be simultaneous for another observer if the observers are in relative motion.
- Time dilation: Moving clocks are measured to tick more slowly than an observer's «stationary» clock.
- Length contraction: Objects are measured to be shortened in the direction that they are moving with respect to the observer.
- Mass–energy equivalence: E = mc2, energy and mass are equivalent and transmutable.
- Maximum speed is finite: No physical object, message or field line can travel faster than the speed of light in a vacuum.
General Relativity is the Theory of Gravitation developed by Einstein in the years 1907–1915. The development of General Relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion; an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics. This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so. To resolve this difficulty Einstein first proposed that spacetime is curved. In 1915, he devised the Einstein field equations which relate the curvature of spacetime with the mass, energy, and momentum within it.
Some of the consequences of general relativity are:
- Clocks run more slowly in deeper gravitational wells. This is called gravitational time dilation.
- Orbits precess in a way unexpected in Newton's theory of gravity. (This has been observed in the orbit of Mercury and in binary pulsars).
- Rays of light bend in the presence of a gravitational field.
- Rotating masses «drag along» the spacetime around them; a phenomenon termed «frame-dragging».
- The Universe is expanding, and the far parts of it are moving away from us faster than the speed of light.
Дата: 2018-12-28, просмотров: 285.