On the Pulsar

The following sections are included:

• Contents

• Foreword

Misha left the main building of Moscow State University. Today the University was open to the senior grade high school pupils, and they were welcome to visit the lecture rooms and laboratories. Misha was dazzled and confused by the endless number of instruments, machines and facilities…

In 1967 a powerful radiotelescope was built in Cambridge to study the interplanetary scintillation of radiowaves. Radiowave scintillations themselves were discovered somewhat earlier in 1964. Let us suppose that there is a radiowave source located very far from the Earth. The radiowaves travel long distances before they reach the Earth's surface, and on the way they pass through clouds of rarefied plasma in interplanetary space. These diffract the waves, and so scintillations occur on these clouds. The study of interplanetary scintillations allows us to obtain very important data on the angular dimensions of a radiosource…

"And now we shall go and see what a pulsar is," said Leonid Andreevich.

"What do you mean?" inquired Misha.

"You will find out very soon," answered Leonid Andreevich, and he invited Misha to follow him.

They left the Professor's room and went to the very end of the corridor. Leonid Andreevich stopped near a large door and pressed some buttons on the coded lock. The door slowly moved aside and they stepped in. Misha never expected to find such a room in the building: they came into a huge round hall with a hemispherical dome which was evenly illuminated by daylight. To tell the truth, Misha thought that they were outside the building, and only after several moments did he understand that they were still indoors. The hall reminded him of the Planetarium, the only difference being that there were no chairs on the periphery. In the centre of the hall there was a large round table instead of the projector that showed the sky and stars. Around the table there were several chairs which looked like dentist's chairs: they could be turned and reclined so that it was very easy to look upwards. Opposite one of the chairs, a large display was installed and it had a computer keyboard beside it. Numerous different things were scattered all over the table. Among them Misha noticed some large glass plates and a box with balls which looked like ping-pong balls. Leonid Andreevich took the chair opposite the display and invited Misha to take a seat next to him. The display showed one line of text, 'Earth, day, cloudy' and some numbers…

Having spent some time at home, Misha decided to visit his friend Sasha. Sasha seemed very smart to him as he was a third year student at Moscow State University's Physics Department. Sasha was always ready to answer any question in physics and mathematics and Misha thought that he knew almost everything about physics. While speaking about his talk with the Professor, Misha briefly mentioned mass anisotropy in a strong magnetic field…

In a week Misha was back in the same hall.

"Today we will play billiards," said L.A. "Not ordinary billiards, but billiards on a pulsar. All the balls have a strongly anisotropic mass, i.e. their transverse mass m_⊥ significantly exceeds their longitudinal mass m_∥. For convenience, we will direct the magnetic field horizontally so that the balls will appear light in the longitudinal direction (along the table) and heavy in the transverse one (across the table)…

"Which of two similar-sized bubbles submerged in water do you think will rise faster — an air bubble or a hydrogen one?" asked L.A. at their next meeting.

"The hydrogen bubble, of course" said Misha without thinking, "hydrogen is lighter than air."

"This time you have been too fast," said L.A. with a smile. "Let us think more thoroughly…

Next time Misha visited L.A. together with his friend Sasha. L.A. was very polite with the boys and then, kidding, he said:

"Well, well, professors. I would like to take you both on a journey. Please, follow me."

He approached a door in his office which Misha had never noticed before. The boys followed the Professor into a medium-sized room, which was decorated like the hall where L.A. performed his experiments. The room was round and the walls and the ceiling merged into a white dome. There were three chairs in the middle of the room; a steering wheel, like the one on a plane, was located in front of the middle chair. The steering wheel was equipped with a number of strange buttons on an instrumentation panel…

"Today we will get acquainted with the behavior of matter in a superstrong magnetic field" L.A. began, when Misha and Sasha next came to him.

L.A. approached a large whiteboard and started his narration.

"We shall begin, naturally, with the simplest objects. Let us begin with a single electron. Classically, an electron is just a charged particle with charge e and mass m. The charge is equal to 1.6 · 10^-19 Coulombs, and its mass is 0.9 · 10^-27 g. A free electron in classical mechanics moves with a constant speed along a straight line, or rests if its velocity is precisely equal to zero."…

"Today I will tell you about neutron stars," said L.A. at their next meeting.

"All stars, including the Sun, are huge balls of gas. Or, rather, they are huge balls of plasma since at high temperature the atoms of ordinary gas break down into their constituent nuclei and electrons. In a plasma, the nuclei look like positively charged ions located in an electron gas. However, from the point of view of expanding when heated, a plasma acts like a regular gas. Thus, a star is a ball of gas prevented from expanding by gravity…

"I'll try to tell you as much as possible about pulsars," said L.A. "Almost as much as I know myself. In doing so, I will present to you my own understanding, which may not necessarily coincide with the opinions of my colleagues who are more experienced in this area. I am not a specialist in astrophysics…

"The question, 'What is life?' is a very complex one," L.A. began his next lecture.

"We will approach this question gradually, step by step, starting from the simplest things. The simplest approach to the explanation of the Universe is based on the statement that the Universe was created by God. I will not go into detail now discussing the role of God. However, there is no reason to think that God started the creation of the Universe by violating His own laws. It is more sensible to assume that the Universe, no matter who created it, is developing in accordance with certain laws. This is why the development of the Universe should be studied on the basis of the assumptions that we have at present, and on the basis of the knowledge of those laws that are considered to be proved in practice…

"Today we will undertake an unusual journey," said L.A. to Misha and Sasha during their next meeting. "We will travel to the Pulsar."

"Really? But how?" uttered Misha.

"I will now explain it to you in more detail. I will have to start from afar. You might have heard about the everlasting dispute about whether sleep is needed by animals and human beings. The simplest explanation is focused on the fact that the brain needs rest: during the daytime the brain is oversaturated by various impressions, and therefore sleep is necessary to calm down, to process the impressions and to move them to more distant memory cells and therefore be ready to accept new impressions. As you probably noticed yourselves, simple and primitive explanations are often far from the ultimate truth. They can fail when discussing complex phenomena. And the process of thinking is one of the most complex phenomena…

The following sections are included:

• Appendix

• Index