6. Under ordinary conditions subatomic particles are considered to be ... .
7. Under immense temperatures and densities ofthe Big Bang they might have undergone....
8. The Big Bang process might have lasted only ....
• Read the passage again and find answers to the following questions.
1. What do contemporary physicists know for certain about matter?
2. What do physicists assume concerning the other types of subatomic particles?
3. Why do physicists insist on the identity ofthe particles?
4. What should happen ifthe particles were not identical?
5. What phenomenon do the physicists call "phase change"?
6. What examples of phase changes could you give?
7. Could subatomic particles experience phase changes?
8. Under what conditions could they have experienced phase changes?
• Think and say a few words about:
a) Big Bang and subatomic world;
b) the matter makeup;
c) phase changes in everyday life and in subatomic world;
d) laboratory experimentation with subatomic particles.
CLASS WORK
READING (13B)
• The problem of the passage below is illustrated in a block-scheme. Look at it and say what you know about the problem. Then, read the passage and find the facts to prove or disprove your ideas.
The Universe
| quarks/gluons |
 | |||
 | |||
| ------ > | field | --- ) |
| <----- |
proton/neutron
PARTICLES AND FIELDS
The number of the particles of each type in the present universe is the result of a complicated history. Most ofthe particle types that were abundant in the early universe have long ago disappeared. We only observe them when they are produced briefly in laboratories, and then annihilate or decay. Because of this we are uncertain of how many particle types may exist.
In the present universe, quarks and electrons have properties that allow them to form the tightly bound clusters that we call nuclei and atoms. Photons and neutrinos cannot do this, and so exist much more diffusely throughout the universe.
Nevertheless, most of the universe we know is made of quarks and electrons, and the present picture we have of the world is largely an expression of the properties of these particles. Of the two, quarks have a greater tendency to cluster together. Indeed, this tendency is so pronounced that most physicists believe that quarks are never found in isolation, but only in combinations containing either three quarks or one quark and one antiquark. These are the combinations that make up most of the subatomic particles that we observe, such as protons and neutrons, the particles found in the nuclei of atoms.
The reasons why quarks insist on clustering in this way are not completely understood. There is a general theory, known as quantum chromodynamics (QCD) that attempts to describe how quarks behave. QCD involves the interactions of fields associated with quarks and fields associated with another type of particle called gluons (so named because they bind the quarks together). Most physicists believe that when the predictions of this theory are better understood, we will know why quarks cluster as they do.
Ever since the first microsecond after the origin of the universe, quarks have been bound together, in groups of three, into neutrons or protons. All of the other combinations of quarks or the other quark types, which also can bind together, are unstable under present conditions. That is, if they are produced, they change spontaneously into less massive particles, and eventually into some combination of the stable ones. Even neutrons are unstable when they are found in isolation — as when they arc produced in nuclear reactors — and decay into protons in a few minutes. The reason that neutrons exist at all in the present universe is that when given the chance they bind together into more complex and lasting objects. Neutrons can bind with protons into atomic nuclei, and with one another in immense numbers into neutron stars.
Electrons also bind with nuclei and with each other into the combinations that we know as atoms and molecules. This binding occurs through electric and magnetic forces, which are manifestations of the same quantum field whose particle aspect is the photon. The detailed properties of this field arc summarized in a theory known as quantum electrodynamics (QED), the most widely tested theory in quantum physics. No inaccuracies have been found in the theory, down to a level of error of less than one part in a billion.
Most physicists believe, on the basis of theoretical arguments, that even protons and bound neutrons are not really stable, and that over sufficiently long periods of time they decay into electrons or neutrinos. Such decays have not yet been observed, although experimental searches are underway. The time period over which this is thought to occur is 1031 years or more, so that few of the protons and neutrons produced in the early universe would have decayed yet in this way. However, by looking at matter containing thousands of tons of protons, a few proton decays should be seen in a year. According to this theory, ifthe universe continues to expand for another 1031 years or more, matter as we know it will have disappeared. The era in which the universe is dominated by the matter familiar to us will be very long by human and by galactic standards, but it may still be just an instant in the whole history ofthe universe.
• Look through the passage and find English equivalents for the following Russian phrases.
современная вселенная; во всей вселенной; сложная история; из-за этого; плотно связанные; выражение свойств; тенденция столь ярко выражена; зарождение (возникновение) вселенной; они спонтанно превращаются в...; через достаточно долгий период времени; экспериментальные исследования ведутся; всеголишь мгновение; стремятся сгруппироваться
• Fill in the blanks with information from the text or from any other source.
1. The matter of the universe is made up of....
2. The general theory describing the behaviour of quarks is....
3. The QCD involves the interaction of... and ....
4. Protons and neutrons arc made up of....
5. The subatorhic particles existing in the universe diffusely are ... and ... .
6. Neutrons can bind with one another into ....
7. QED involves the binding of... and ... into ....
8. The subatomic particles never found in isolation arc ....
• Choose the facts from the list below which you could consider as well-established by science. Give reasons for your choice.