Гвоздева Пхысицс фор адванцед студентс 2011

Part III. MODERN PHYSICS

UNIT 1

ATOMIC PHYSICS

FYI

‘Atomon’ is the Greek for undivided.

PRE-READING TASK

I one(s) is used to refer to a thing(s) that has been mentioned before.

Study the sentences.

1 The shift from a Newtonian cosmology to an Einsteinium one is presently taking place in human understanding.

2.The universe started as a mathematical point and then there was a big explosion. The spiral nebulae, the most distant objects in the sky, are the ones that were shot out fastest and have gone the farthest from us.

3.New problems couldn’t be solved by old methods and required radically new ones.

II that (those) is used to refer to a thing(s) that has been mentioned before.

Study the sentences.

1.The Mar’s axis is tilted to a similar degree as that of Earth.

2.The difference between the classical physics and the modern one is that between logical and illogical physics.

3.The key physical properties of Mars are remarkably similar to those of Earth.

III. S + appears + to V = Russian – Кажется, что; Оказывается,

что + S

Study the sentence.

What we see appears to result from happenings in a region where

laws are still unknown.

IV. We use is, are, was, were + to V (to be + V3) to say that something is planned to happen.

Study the sentences.

1. Observation disturbs the things which are to be observed.

− 91 −

2. We must find out what happens at these energies if we are to understand how we and the universe began.

3 “Humanity needs a substantially new way of thinking if it is to survive.” (Einstein)

Give Russian correspondence:

rather than (instead of), from (on the basis of), plenty of (lots of), moreover (more than that), a number of (a set of, a range of), so (thus), to result from (to be caused by), because of (due to), continuously (nonstop), via (through, by means of), although (though)

LOGICAL AND ILLOGICAL PHYSICS

“Modern physics deals with probabilities.”

Edenton

Study the passage. Mind the underlined grammar points.

The difference between the classical physics and the modern one can be explained quite simply. The difference is that between logical and illogical physics. Classical physics deals with physical phenomena in a direct rather than a mathematical sense. Physics is a consistent scheme that allows getting predictable results from the measurements of physical experience. The validity of a theory rests on its ability to predict the results of experiments correctly. But the trouble was that the experimental side of science was lagging behind the theoretical. There were plenty of problems over the horizon and these problems could not be solved by the old methods but required radically new ones.

The new world of atomic physics can’t be fitted into the mechanical models of the 19th century or, indeed, into any model which could be visualized. Physicists have met the situation by abandoning the use of concrete models, and started to express the results in mathematical equations. Moreover, these equations express only statistical averages or probabilities. We cannot say when any radioactive atom will explode. All we know is that in any time interval a number of atoms will explode.

So, the universe can’t be regarded as completely unknown; what we see appears to result from happenings in a region where the laws are still unknown, and, may be unknowable because of the crudity of our instruments and the fact, as Heisenberg pointed out, that there are some

− 92 −

CLASS EXERCISES

Exercise 1 (do it yourself, then check up the completed sentences in groups.)

Complete the sentences.

1.The difference between the classical physics and the modern one

……… quite simply.

2.The difference … that … logical … illogical physics

3.Classical physics …….. physical phenomena …. a direct sense

4.Modern physics …… physical phenomena … a mathematical

sense

5.Physics …. a consistent scheme that allows getting … results from the measurements of ……

6.The validity of a theory ….. its ability to predict the results of experiments ……

7.The trouble … that the experimental side of science ……. the theoretical.

8.New problems ……. by the old methods

9.They …. radically new methods.

10.Physicists started to express the results in …. …

11.Modern physics … .. probabilities.

THE ATOMISTIC STRUCTURE OF MATTER

FYI

a nucleus (sing) – nuclei (pl)

Run through the passage and do the exercise that follows.

There are only 100 different kinds of atoms in the entire universe. Everything we see is made up of those 100 atoms in an unlimited number of combinations. How these atoms are arranged and bonded together determines whether the atoms make up a cup of water, a piece of metal, or the fizz that comes out of your soda can?

Atoms are in constant motion. They continuously vibrate, move and rotate. Atoms can be in different states of excitation. In other words, they can have different energies. If we apply some energy to an atom, it can leave what is called the ground state energy level and go to an ex-

− 94 −

cited one. The level of excitation depends on the amount of energy that is applied to the atom via heat, light, or electricity.

This simple atom consists of a nucleus (containing protons and neutrons) and an electron cloud. It is helpful to think of the electrons as circling in many different orbits. Although more modern views of the atom do not describe discrete orbits for the electrons, it can be useful to think of these orbits as different energy levels of the atom. In other words, if we apply some heat to an atom, we might expect that some of the electrons on the lower energy level would transit to a higher energy orbit.

Vocabulary Notes

1.to arrange – to organize

2.a can – a tin, a metal container

3.to extend – to widen

4.a bond – a link – a connection

Exercise 2

Explain in other words.

1.Atoms are in constant motion

2.Atoms can be in different states of excitation

3.Discrete electron orbits

UNIT 2

A CHANCE TO LOOK INSIDE

PRE-READING TASK

I. We use two variants.

1.It was found that the nucleus was composed of the so-called elementary particles.

2.The nucleus was found to be composed of the so-called elementary particles.

We also use these structures with:

is thought; is believed; is supposed; is expected; is considered (считают, полагают)

is said (говорят); is known (известно) is proved (доказано)

− 95 −

Study the sentences.

1.It was believed that everything was composed of indivisible and indestructible atoms.

2.Everything was believed to be composed of indivisible and indestructible atoms.

II. If we want to emphasize a word or a part of the sentence we use this structure:

It is …… that … = именно, только Study the sentences.

1.It is only when we extended our observations to smaller length scales and higher energies that we have discovered new layers of structure.

2.It is the discovery of Brownian motion that showed that matter is not continuous.

Give Russian correspondence:

at least (as a minimum), twice (two times), in terms of (through, by means of), a number of (a set of), certain (particular), the only (single), the very, let alone (to say nothing about), continuous (ant. discrete), shortly thereafter (soon after that), in its turn, the very short (the shortest), because of (due to)

IS THERE A LIMIT TO THE LAYERS

OF THE STRUCTURE OF MATTER?

FYI

1.Continuum is a long series of things in a particular order. Each thing is closely related to the thing which is next to it in the order.

2.Mechanics is the part of physics which deals with forces acting on moving or stationary objects.

Study the passage. Mind the underlined grammar. Translate the paragraph marked with asterisks in writing.

Physics was thought to be over at least twice before. At the beginning of the twentieth century everything was believed to be understood in terms of continuum mechanics. All that was needed was to measure a certain number of coefficients of elasticity, viscosity, conductivity, etc. This hope was shattered by the discovery of atomistic structure and

− 96 −

quantum mechanics. Again, in the late 1920s Max Born told a group of scientists visiting Gottingen that ‘physics, as we know it, will be over in six months’. This was shortly after the discovery by Paul Dirac of the Dirac equation, which governs the behavior of the electron. As Dirac pointed out, his equation was the basis of ‘most of physics and all of chemistry’. A similar equation is expected to govern the proton, the only other supposedly elementary particle known at that time. However, we have been able to solve the equation only for the very simplest system, the hydrogen atom, consisting of one proton and one electron. However, the discovery of the neutron and of nuclear forces disappointed these hopes. For more complicated atoms with more electrons, let alone for molecules with more than one nucleus, we have to resort to approximations and intuitive guesses of doubtful validity.

Each time we have extended our observations to smaller length scales and higher energies, we have discovered new layers of the structure of matter. At the beginning of the last century, the discovery of Brownian motion with a typical energy particle of 3 x 10−2 eV showed that matter is not continuous but is made up of atoms.

*Shortly thereafter these supposedly indivisible atoms were found to be made up of electrons revolving about the nucleus with energies of the order of a few electron-volts. The nucleus, in its turn, was found to be composed of the so-called elementary particles, protons and neutrons, held together by nuclear bonds of the order of 10 eV. The proton and electron have been found to be made up of quarks held together by bonds of the order of 109 eV.*

Our past experience might suggest that there is an infinite sequence of layers of structure at higher and higher energies. However, it seems that gravity should provide a limit, but only at the very short length scale of 10−33 cm or the very high energy of 1028 eV. On length scale shorter than this, one would expect that space-time would stop to behave like a smooth continuum and that it would have a foamlike structure because of quantum fluctuations of the gravitational field.

Stephen Hawking

Vocabulary Notes

1. Elasticity is the ability of a material to return to its original shape after it has been stretched

− 97 −

3.The hydrogen atom is the very simplest system.

4.The hydrogen atom is composed of one proton and one electron.

5.Protons and neutrons are held together by nuclear bonds of the order of 106 eV.

6.All particles are made up of perhaps six different varieties of quarks.

7.Quarks are held together by bonds of the order of 109 eV.

8.The track a particle makes when going through a bubble chamber is almost straight.

Exercise 2 (class activity) A Round Table Talk

‘The Atomistic Structure of Matter’

Every student makes his contribution to the discussion.

UNIT 3

ELEMENTARY PARTICLE PHYSICS

“I ask you to look both ways. For the road to the knowledge of the stars leads through the atom, and important knowledge of the atom has been reached through the stars.”

Edenton

PRE-READING TASK

Give Russian correspondence:

once (in the past), except for (but), both ………. and, as (when, while, since), yet (but), in favor of (ant. against), in a favorable way, thus (therefore), too + adj. , after, another (one more), as to (about, concerning), either …….. or, the former ………… the latter, to realize (to understand)

THE FIRST ATOMS

Study the passage. Mind the underlined grammar points.

In a tiny fraction of the first second after the Big Bang what was once a complete vacuum began to evolve into what we know now as the universe. In the beginning, there was nothing except for a plasma soup.

− 99 −