Английский язык для студентов-физиков (стр. 5 )

This scenario should not surprise us. If the most important constituents of the present Universe are destined to disappear, they will surely be replaced by something new. From what we know of the past evolution of the Universe this has happened several times in the past as the Universe went from one dominated by many distinct particle species to one dominated by photons to one dominated by protons.

Some physicists have tried to describe the Universe that would develop after the protons have decayed or the black holes have swallowed up matter as we know it. These considerations would apply either to the large finite Universe of the present scenario (so long as it is still expanding) or to the next scenario, in which the Universe is finite and expands forever. The analysis is not complete, but it suggests that some forms of matter other than photons would persist (continue to act) in such a future Universe.

The protons that are present in our Universe would decay into positrons. These positrons can annihilate with the electrons already present to yield photons. *However, the extent to which this happens depends on the rate of expansion of the Universe, which by increasing the average distance between particles, decreases the chance of annihilation. The analyses that have been given suggest that many of the positrons will Find themselves too faraway from an electron to annihilate. Consequently, some positrons, and an equal number of electrons, will remain indefinitely. The same appears to be true for neutrinos of finite mass, if there are any such particles. In any event, these particles that remain could form more complex stable structures, bound together by gravity orelectromagnetism. These structures will be immensely largerthanthe familiar atoms, indeed, some maybe larger than the present observable Universe!

How complex these structures can become is an unsolved problem. It is difficult to analyse it in detail, because of the extreme disparity in scale between the structures that are familiar to us and anything that may evolve in the late

Universe. However, this change in scale is not unprecedented in the history of the Universe. *In its earliest moments, the whole region that eventually evolved into the present Universe was much smaller than an atom or even a subatomic particle. *If there could have been an intelligence that functioned in the early instants of the Universe, the familiar structures of our present Universe would seem as grossly extended as the supergalactic atoms of the late Universe would appear to us. *It is not beyond our ability to understand complexity in the late Universe, once we set our minds to it. 1 believe that understanding that complexity, and solving its related problems, will represent a novel branch of science in the future.

*No matter how large, ifthe Universe is finite, eventually the expansion will cease and contraction will take over. The details of what will happen during this contraction would be rather different from those in Scenario 1, because the contents of the Universe would be different in each case. *Yet, the outcome is no less mysterious, so poorly are the phases of turnover and contraction under­stood. *If we learn that the Universe is finite, unraveling what will take place during these phases will become one of the important endeavours of future science.

•  Try to guess the meaning of the words given in italics in the text.

•  Translate the sentences marked with an asterisk.

•  Look through the text and try to answer the following questions.

1.  What conditions are needed for the Universe to be larger than that in Scenario 1?

2.  What will the future of the Universe depend upon according to Scenario 2?

3.  Why is Scenario 2 of greater interest to scientists as compared with Scenario 1 ?

4.  What do scientists hypothesize concerning the present forms of matter?

HOMEWORK

(to be done in writing)

1. Translate into Russian.

1.  In one specific cosmological model, recently proposed by an American physicist Alan Guth, known as the inflationary universe, all of the visible universe and a great deal of space-time beyond it, originated in a tiny bubble in the very early universe.

2.  This bubble contained a high level of quantum fields which caused it to undergo an expansion much more rapid than that expected according to

the standard Big Bang theory, where the expansion is influenced only by the presence of subatomic particles.

3.  The rapid expansion diluted the material contents of our universe to a very low density, and none ofthe particles present in the universe before this "inflation" began are present today.

4.  Instead, the matter in the present Universe was produced by a phase transition at the end ofthe inflation, in which some of the energy that was contained in background fields became converted to particles.

5.  Inthc inflationary Universe, space-time beyond the volume of expansion ofthe original bubble would be different from space-time inside it.

6.  In this model, the different regions of the Universe arc somewhat like different cultures, developing independently of one another, and unaware of each other's existence.

7.  We are presently unaware of conditions beyond our own bubble, because there has not yet been enough time since the beginning of the Universe for any light originating outside to reach us.

8.  If the Universe continues to exist indefinitely, we would eventually become aware of these foreign regions of space-time — and find that matter and energy in these regions have very different properties from those familiar to us.

2. Translate into English.

1.  Этот журнал содержит ряд статей на данную тему.

2.  Если бы вам удалось достать его, мы могли бы получить много ценной информации.

3.  Одна из статей даст интересную трактовку (treatment) данной темы.

4.  В ней дается обзор (review) данной темы в целом.

5.  Я думаю, что эта статья представляет собой ценный вклад в науку.

UNIT EIGHT

GRAMMAR: THE SUBJUNCTIVE MOOD

1.

It is essential desirable doubtful, etc.

2.

The laws of mechanics require suggest

demand propose, etc.

that the distance of each body (should)be related to...

Законы механики требуют, что­бы расстояние каждого тела... находилось в соответствии с...

If

Provided

Providing

Supposing

the Moon were one halfit would "]

might I be. could J

Если бы Луна составляла половину то она была бы...

If it were to + Infinitive = если бы (относится к будущему) If I were to do that, what would you say?

• Read the following extract. Pay attention to the grammar forms in bold type. Translate them into Russian.

1. Now it is essential that astronomers (should) determine the mass of large numbers of other objects in the Universe. There is the Moon, for instance,

62

Earth's one satellite, which is 384,00 km from us (1 km is = 5/8 mi) and which circles the Earth once every 27 1/3 days.

More precisely both the Earth and the Moon circle a common center of gravity.

2. The laws of mechanics require that the distance of each body from that center of gravity (should) be related to its mass. In other words, if the Moon were one half as massive as the Earth, it would be two times as far from the center of gravity as the Earth is, if it were one third as massive as the Earth, it would be three times as far; and so on.

After Isaac Asimov. "The Collapsing Universe".

WORD AND PHRASE STUDY

Question п. — вопрос, проблема

v. — сомневаться, ставить под вопрос

in question — исследуемый, рассматриваемый

(syn. involved о ко юром идет речь, concerned, in issue, in point)

open to question — сомнительный, спорный

beyond question — вне сомнения

out ofthe question — не может быть и речи

Translate into Russian.

1.  The method involved provided them with interesting results.

2.  The quantity in question is related to the volume of this container.

3.  Our being close to the solution ofthe problem is out of the question.

READING (8A)

• Read the passage and answer these two questions:

1.  What does the Universe look like according to the chaotic inflation hypothesis?

2.  What cosmological problems does this hypothesis account for?

CHAOTIC INFLATION

Like all inflationary scenarios, chaotic inflation removes the monopole problem. No new monopolcs arc created after the inflation, so any that originaliy existed arc separated from one another by an amount in proportion to the magnitude of the exponential increase in the size of the Universe. The i ntc - tor of each domain looks like a mini-Universe with a typical size greater than the distance we can see. UP cm, and for all practical purposes ourdomain is the Universe. But according to this scenario there arc many such mini-Universes separated from each other by domain walls in which the scalar fields take different values and in which, therefore, different laws ot'ohys'cs operate. We live in a domain in which the interactions just happen to have been broken into the strong and weak forces and elcctromagnetism. This has clearly influenced the development of life as well as the evolution of the Universe as we know it, and life of our type may be impossible in other aomains with different laws of physics.

The division of the Universe into many mini-Universes also makes it possible to suggest an answer to the question of why our space is three-dimensional. The process of compactification (shrinking and rolling up of some of the original dimensions) may occur differently in domains that are far enough apart from one another. And, once again, life, as we know it, may only exist in those domains which are three-dimensional. The physicist Paul 'ihrenfest pointed out, as long ago as 1917, that the threc-dimcnsienality of space is intimately connected with the way matter behaves.

Both gravitational and electromagnetic forces obey inverse square laws in our Universe and by generalizing the equations that describe these interactions and solving them in other dimensions mathematicians have shown that in space with n dimensions the result is always an n— 1 power law. In four dimensions, the laws would both be inverse cubes and, it turns out, there would be no stable orbits for cither planets in solar systems or electrons in atoms. The same is true for all higher dimensions. In a two-dimensional Universe, tilings are no better, because n— 1 is 1, and neither gravity nor elcctromagnetism is affected by distance at all. So atoms and planetary systems may only exist together in a domain with three dimensions of space, like our domain of the Universe. Sothc chaotic inflation scenario provides a simple solution to most of the problems with the standard big bang model.

The inflationary Universe scenario is now only five years old, and is still rapidly changing and developing as new ideas come to the fore. We do not know which part of the scenario will survive even for the next five years. But already it has proved able to solve about ten major cosmological problems in one simple model. Ideas which would have sounded like fantastic science-fiction only a decade ago, such as the creation of all the matter in the observable Universe (I0-" tons) by gravitational forces operating inside a domain which originally contained less than 10s g of matter and was less than 10"" cm across, now seem to be necessary ingredients in any complete theory of the Universe.

And how long did all that activity take? 1 have saved the most startling fact until last. The phase of exponential inflation that is critical to our modern understanding of the Universe probably lasted for less than 10'30 seconds.

• Look through the passage and find English equivalents for the following Russian phrases.

достаточно далеко отстоять друг от друга; подчиняться закону об­ратных квадратов; степенной закон; то же справедливо и для; ситуа­ция не лучше и для; по мере выдвижения новых идей; дает простое решение; являются, по-видимому, необходимыми составляющими; по­разительный факт; принимают различные значения; для решающего (переломного) понимания

• Match each word in A with its synonym in B.

A. 1. to survive; 2. ingredient; 3. to startle; 4. to shrink; 5. true

B. a) component; b) to astonish; c) to remain alive; d) to contract;
e)exact

• Match each word in A with its antonym in B.

A. 1. to stop; 2. to shrink; 3. far apart from; 4. slow; 5. true; 6. inverse;
7. to survive

B. a) direct; b) to expand; c) rapid; d) next to; c) false; 0 to die; g) to
last

• Answer the following questions using the information from the text or any other sources.

1.  What is the Universe according to the chaotic inflation scenario?

2.  What problems does the chaotic hypothesis remove and why?

3.  What does each domain of the Universe look like?

4.  How does this hypothesis explain the dimensionality of our system?

5.  How does the author account for the first instants of the origin of the Universe?

6.  What really fantastic science-fiction figures do scientists have to realize in developing a complete theory of the Universe?

7.  Which of the facts impress your imagination most?

1 Г.. И. Куршпии.-н

65

CLASSWORK

READING (8B)

Before reading the passage below, let us remember Scenarios 1 and 2 of a finite small and large Universes.

Scenario 1

Scenario 2

Condition

Enough matter for the Universe to close on itself.

The density of energy in the Universe is slightly larger than needed for the Universe to close.

Scenario 1

Scenario 2

Consequences

1.  Middle-aged Universe.

2.  Expansion —> stop —» contraction —> Big Crunch.

3.  Protons will not have time to decay.

1.  The Universe is in its infancy.

2.  Very long expansion —> stop —> contraction —> Big Crunch.

3.  Decay of protons into lighter particles, spontaneous collapse of matter into black holes. Annihi­lations of neutrinos and anti-neutrinos. I nstability of galaxies.

• Now, read the passage and give your opinion on the fate of the Universe according to Scenario 3.

SCENARIO3. AN INFINITE UNIVERSE

*If the density of matter were less than a critical amount, corresponding to aboutgrams per cubic centimeter — about ten milligrams in a region the size of the Earth — then the Universe is infinite, and will expand for ever. "■Objects in the Universe will, on the average, get farther and farther apart, except for those such as the contents ofthe solar system, which are held together by forces such as gravity. As in Scenario 2, the contents of the Universe will change, and their eventualform will depend on presently unknown properties of subatomic particles and on the end state of black holes. On the whole, the future ofthe Universe in Scenario 3 is about the same as in Scenario 2, except that the expansion never slows to zero and reverses. The Universe of Scenario 3 becomes one in which protons, electrons, neutrinos and their antiparticles are spread ever more thinly through larger and larger regions of space. *Once again, however, we do not know whether gravity and elcctromagnetism would allow these objects to form complex structures able to persist indefinitely.

However, there is a missing piece in our puzzle, one that might apply to the large finite Universe. Most cosmological models have assumed that the Universe is homogeneous — that all parts of it are the same, including those beyond the reach of our telescopes and hence unknown. The assumption of homogeneity has been made in order to simplify the mathematical description that physicists give to the Universe.

*Recently, this assumption has been questioned. We have seen that physicists believe that some features of the present Universe depend on the broken symmetry that occurred in the early Universe. Yet this symmetry breaking need not have occurred uniformly over the whole of spacetime. Just as a lake in winter can be liquid in some regions and solid in others, so might different regions of space be in different phases, which would imply different physical properties for the matter in it. For example, the surplus of what we call matter in our visible Universe might be replaced by equal amounts of matter and ant imatter or a surplus of antimatter in parts of space-time beyond our present horizon. But now let us return to the view that the properties of particles will change slowly as the Universe expands. Some scientists have predicted that rapid phase transitions similar to those that took place in the early Universe will occur in the future. This could happen if the present configuration of quantum fields in our region of space has more energy than another configuration, and is therefore unstable against transformation into the lower energy configuration.

*lf such phase transitions occur, they are expected to begin in one place, perhaps as the result of a random fluctuation, and then spread outward at the speed of light, eventually encompassing every point in space. *As the transition passes through any point, those properties of matter that depend on the background quantum fields present there, would have to change suddenly because of the new conditions. *A sudden change in the properties of subatomic particles would lead to tremendous changes in any structures composed of Ihcm, and it is unlikely that these structures would persist. It has even been suggested that such a phase change has begun in anothersection ofthe Universe, and is now approaching us at the speed of light. But there is no evidence forthis possibility, and we need to analyse it further before adding it to the list of environmental catastrophes that we need to worry about.

If the Universe continues to expand long enough for the matter to change its form drastically, then intelligent creatures may have agreater role to play in the distant future than they would in a Universe that eventually contracts. They would have to grapple with two problems: the disappearance of the protons and bound neutrons that form the material bases for most structures in the present Universe, and the ever smaller amounts of free energy that would be available to preserve order in whatever structures might replace them. *No good solutions to these problems have yet emerged, but since we have been studying them for only a few years, and will not need the answers for 10J0yearsorso, wc need not despair.

•  Try to guess the meaning of the words given in italics in the text.

•  Translate the sentences marked with an asterisk.

•  Look through the text and try to answer the following questions.

1.  What conditions arc needed for our Universe to be infinite?

2.  What factors will play the key role in the fate of an infinite Universe?

3.  What fatal consequences could the inhomogencity of the Universe lead to?

4.  Are there any reasonable solutions to the problems?

5.  Why does the author think that human beings need not despair about the future of the Universe?

HOMEWORK

(to be done in writing)

1. Translate into Russian.

1.  To a physicist a liquid is very symmetric — whichever way you look at it, it looks the same.

2.  But when the liquid cools and begins to crystallize, different regions of the liquid may begin to crystallize with different orientations of their growing crystal lattices.

3.  When these different crystal lattices meet one another they join together as best as they can and inevitably produce boundaries called defects.

4.  Within each domain there is a preferred orientation ofthe crystal lattice, but adjacent domains separated by a defect may have very different orientations.

5.  The overall symmetry has been destroyed.

6.  During the phase transitions ofthe cooling early Universe, something similar to the crystallization of a liquid may have happened.

7.  As the Universe continued to expand and cool, the quantum fields went through several distinct phase transitions.

8.  Each of these led to a change in the overall level of quantum fields everywhere in space and an associated change in the properties of some subatomic particles.

9.  The last of the phase changes is thought to have taken place when the temperature ofthe Universe was about 1011 times as great as today.

10. After that, all subatomic particles had the same properties that we find them to have now.

11. According to theoretical analyses, all of these extraordinary changes took place within a very short period of time — perhaps in the very microsecond or so after the expansion ofthe Universe began.

12. In other words, the main subatomic features of our Universe were determined in a flash of time, and the consequences have been working themselves out ever since.

2. Translate into English. Use such phrases as in question (progress), under consideration (discussion, study).

1.  Открытие, о котором идет речь, пока широко не известно.

2.  Исследуемая проблема может повлиять на развитие всей от­расли.

3.  Обсуждаемые сейчас данные тесно связаны с этой проблемой.

4.  Рассматриваемый подход кажется вполне удовлетворительным.

5.  Исследовательская работа, проводимая в нашей лаборатории, даст хорошие результаты.

Part III.

THE WORLD OF SUBATOMIC PARTICLES

UNIT NINE GRAMMAR'. THE SUBJUNCTIVE MOOD

1 как если бы, как будто бы

as though

The object behaves as if it were Тело ведет себя так, как будто бы

given some energy at the start. ему сообщили...

для того чтобы

2. that
so that
in order that
lest чтобы не

Keep the temperature so that the Поддерживайте необходимую substance (should) not be cooled. температуру, чтобы вещество не

остыло.

3. though J хотякакбыни
although J

Though he may (might) be busy he Как бы он ни был занят, он за-will complete the work on time. кончит работу вовремя.

Sentences to be translated.

1.  Acid is added so that the metal should dissolve.

2.  This gas must be kept in a special vessel lest it be evaporated.

3.  Though such an apparatus be developed, this would not solve the problem.

4.  One cannot speak of particles and waves as though they were two different things.

5.  Make exact calculations lest you should fail with your experiment.

6.  Be careful lest you should make mistakes in calculations.

7.  In determining the orbit of a planet we may neglect accelerations ofthe sun and treat it as if it were at rest.

WORD AND PHRASE STUDY

A +	-iy =	Adv
accurate +	-iy =	accurately

• Form adverbs from the following adjectives and translate them *****ssian.

pure, comparative, rapid, equal, ordinary, certain, accidental, radioactive, previous, rare, heavy, presumble

READING (9A)

• Read the passage attentively and be prepared to describe the phenomenon of natural radioactivity.

THE DISCOVERY OF RADIOACTIVITY

As is the case with so many other discoveries, the discovery ofthe phenomenon of radioactivity was purely accidental. It was discovered in 1896 by a French physicist, A. H. Becquerel (1852—1908), who was interested at that time in the phenomenon of fluorescence, i. e. the ability of certain substances to transform the ultraviolet radiation that falls on them into visible light. In one of the drawers of his desk Becquerel kept a collection of various minerals that he was going to use for his studies, but because of other pressing matters, the collection remained untouched fora considerable period of time. It happened that in the drawerthere were also several unopened boxes of photographic plates, and one day Becquerel took one of the boxes in order to photograph something or other. When he developed the plates he was disappointed to find that they were badly fogged, as if previously exposed to light. A check on other boxes showed that they were in the same poor condition, which was difficult to understand since all the boxes were sealed and the plates inside were wrapped in thick black paper. What could be the cause of this mishap? Could it have something to do with one ofthe minerals in the drawer? Being of an inquisitive mind, Becquerel investigated the situation and was able to trace the guilt to a piece of uranium ore labeled "Pitchblende from Bohemia". The reader must take into account, of course, that at that time the name "uranium" was not in vogue as it is today, and that, in fact, only very few people, even among scientists, had ever heard about that comparatively rare and not very useful chemical element. But the ability of a uranium compound to fog photographic plates through a thick cardboard box and a layer of black paper rapidly brought this obscure clement to a prominent position in physics.

The existence of penetrating radiation that could pass through layers of ordinarily opaque materials as if they were made of clear glass was a recognized fact at the time of Becquerel's discovery. In fact, only a year earlier (1895) a German physicist, Wilhclm Roentgen (1845—1923), discovered what arc now known as X-rays, which can penetrate equally well through cardboard, black paper, or the human body.

Although special high voltage equipment is required to produce X-rays, the radiation "discovered by Becqucrel was flowing quite steadily and without any external excitation from the piece of uranium ore resting in his desk. What could be the origin of this unusual radiation? Why was it specifically associated with the clement uranium and, as studies found, with two other heavy elements known as thorium and actinium? The early studies of the newly discovered phenomenon, which was called "radioactivity", showed that the emission of mysterious radiation was completely unaffected by physical or chemical conditions. We can stick a radioactive element into a very hot flame or drop it into liquid air without the slightest effect on the intensity ofthe mysterious radiation it emits. No matter whether we have pure metallic uranium, or its oxide which is contained in pitchblende, the radiation flows out at a rate proportional to the amount of uranium in the sample. These facts ruled out any possibility of ascribing the phenomenon of radioactivity to any kind of chemical properties of this element, and led the early investigators to the conclusion that the phenomenon of radioactivity is the intrinsic property of the atoms of these peculiar elements and that its cause must be deeply rooted in the atomic interior.

• Find equivalents for the following Russian phrases.

как это происходит со многими другими открытиями; чисто слу­чайное; интересоваться; видимый свет; из-за других неотложныхдел; в течение значительного периода времени; проявить пластины; были в таком же плохом состоянии; причина этой неудачи; могло ли это быть связано с; быть популярным; проникающая радиация; светоне­проницаемые материалы; на излучение совершенно не влияет; без ма­лейшего влияния; эти факты исключали возможность; причина, дол­жно быть, кроется; внутреннее строение атома.

Re-read the passage and answer the following questions.

1.  Who was the phenomenon of natural radioactivity discovered by?

2.  Was this discovery really made quite accidentally?

3.  What problem did Becquerel study at the time?

4.  What did he keep minerals for in one ofthe drawers of his desk?

5.  What did he see when he developed the photographic plates?

6.  Why did he begin checking all the boxes with the plates?

7.  Under what conditions were the boxes kept?

8.  What was the cause of this mishap?

9.  Was Becquerel greatly surprized to discover the radiation?

10.  What penetrating radiation was discovered a year before that?

11.  Who discovered this radiation?

12.  Who were the first investigators ofthe phenomenon of radioactivity discovered by Becquerel?

13.  What conclusion did the first investigators come to? Why did they come to such a conclusion?

14.  What substances is the radiation emitted from?

Be prepared to say a few words about.

1.  The history ofthe discovery of natural radioactivity.

2.  Radioactive elements and types of radioactive emissions.

3.  Radioactive processes in nature.

4.  Radioactive emissions and their applications (radioisotopes, radiobiology, radiocarbon dating, radiodiagnosis).

Match each word in Column I with its synonym in Column II.

to be the case, because of, since, to take into account, no matter, to affect, to cause, to be in vogue, to rule out

II

to exclude, regardless of, to influ­ence, because, to happen, to be in fashion, on account of, to take into consideration, to bring about

• Fill in the blanks with the proper word using the words in brackets.

(purified, purely, purification)

1. The process of... is rather complicated.
It is a... theoretical problem.

How is the material... in this case?

The discovery ofthe phenomenon of radioactivity was... accidental. (excited, excitation)

2. The radiation discovered by Becquerel was flowing without any external
... from the piece of uranium ore.

The highly... atoms arc often called Rydbergatoms, aftcrthe Swedish spectroscopist Yohanncs Rydberg.

Both the ion and target atom undergo electronic... during the collision. (exposed, exposure)

3. The technique is based on the use of long... to record an object's motion.
The plates were badly fogged, as if previously... to light.

Several ofthe animals which were... to radiation have died since.

CLASSWORK

READING (9B)

• Skim the passage rapidly (2 min.) and answer the following questions.

1.  Did Becquerel observe in the experiment exactly what he expected to see?

2.  What three rays did the original beam split into?

3.  What were these rays called?

In order to study the nature of the discovered radiation, Becquerel arranged the following very simple experiment. He placed a small amount of uranium in a deep hole made in a lead block so that only a thin beam of radiation emerged from the groove. He also placed a magnet over the block in such a way that the magnetic lines of force were running perpendicular to the direction of the emerging beam. Under these conditions one could expect three different results.

If the radiation emitted by uranium were short electromagnetic waves similar to X-rays, no deflection should take place.

If, on the otherhand, the radiation were fast-moving electric particles, like the cathode and anode rays in J J. Thomson's tube, the beam should be deflected to the left in the case of a negative charge and to the right in the ease of a positive one. In Becquerel's experiment all three things happened, and the original beam emerging from the hole split into three parts. The part that consisted of particles carrying a positive charge was named ос-rays and was later proved (by Rutherford) to be a stream of doubly ionized helium atoms, i. e. a stream of helium nuclei. The part consisting of negatively charged particles, which turned out to be ordinary electrons, was named fj-rays, whereas the undeflected beam formed by short-wave electromagnetic radiation similar to X-rays received the name of y-rays.

•  Re-read the passage and say a few words about the three kinds of radioactive rays. Give a headline to the text.

•  Give a free translation of the following passage.

До открытия природной радиоактивности в конце XIX в. ядерные процессы оставались неизвестными.

Испускание излучения ураном, открытое в 1896 г. А. Беккерелем, было первым явлением ядерного происхождения, наблюдаемым чело­веком. В то время были только что открыты В. Рентгеном Х-лучи, созда­ваемые катодными лучами втрубках, в которых наблюдаласьтакже силь­ная флуоресценция. А. Пуанкаре выдвинул гипотезу, что испускание X-лучей может быть связано с явлением флуоресценции. А. Беккерель, желая проверить это предположение, использовал в качестве флуорес­цирующих веществ соли урана, применявшиеся в работах его отцом. Он обнаружил, что соли действительно испускают излучение, способное производить фотографическое действие через л исток бумаги и ионизи­ровать воздух подобно рентгеновским лучам, однако испускание этого излучения наблюдается также хорошо и с нефлуоресцирующими со­единениями урана. Мари Кюри предприняла изучение этого нового явления в декабре 1897: она произвела ионизационным методом точ­ное измерение интенсивности излучения урана и показала, что анало­гичное излучение испускается торием.

HOMEWORK

(to be done in writing)

1. Translate into Russian.

1. It is necessary that the intensity of radiation should be measured very accurately.

2.  The object behaves as if it were given some energy at the start.

3.  Keep the temperature lest the substance should be overcooled.

4.  In some calculations the air is treated as if it had no viscosity.

5.  He suggested that the tunnel diode devices should be constructed from heavily doped semiconductors.

6.  The whole weight of a body acts as though it were concentrated at a single point, this point being called the centre of gravity.

7.  It is desirable that the errorsignal should be isolated from the detector.

8.  The laws of mechanics require that the distance of each body from the center of gravity should be related to its mass.

2. Translate into English.

1.  Предлагается, чтобы эксперименты провели в совершенно иных условиях.

2.  Как бы мне хотелось принять участие в этой конференции!