Time Travel and New Universes
It is known that for a long time well before Albert Einstein scientists were studying the ideas that seemed strange. Consider a few of such ideas now accepted by the scientific community: clocks that tick slower when they are on rockets in outer space, black holes with the mass of a million stars compressed into a volume smaller than that of atom and subatomic particles whose behaviour depends on whether they are being watched.
But of all strange ideas in physics, perhaps, the strangest one is the hole in the structure of space and time, a tunnel to a distant part of the universe. American researchers have determined that it will apparently be possible in principle for mankind to create an entirely new universe by using the idea of wormhole (ход, прорытый червем) connection. Such a universe will automatically create its own wormhole, squeeze through it, and then close the hole after it.
Although to many people such an idea may seem useless and fantastic, it can help scientists to develop their imagination and explore how flexible the laws of physics are. It is such an idea that could give answers to some of the fundamental questions of cosmology: how the universe began, how it works and how it will end.
The idea of wormhole comes directly from the accepted concepts of general relativity. In that theory A. Einstein proved that very massive or dense objects distort space and time around them. One possible d stortion is in the form of a tube that can lead anywhere in the universe - even to a place billions of light years away. The name "wormhole" comes about by analogy: imagine a fly on an apple. The only way the fly can reach the apple's other side is the long way over the fruit's surface. But a worm could make a tunnel through the a .viand thus shorten the way ccrsideratly. A worrrhole in space h the same kind of tunnel; it is a shortcut from one part of the universe to another that reduces the travel time to about zero.
In fact, instantaneous travel leads to the idea of wormhole as time machine. If it were possible to move one end of a wormhole at nearly the speed of light, then, according to general relativity, time at that end would slow down and that part of the tunnel would be younger than the other end. Anything moving from the faster-aging end of the wormhole to the slower one would essentially go backward on time. The type of travel, however, could be nothing like the mechanical time machine described by H. Wells. It is difficult to imagine how a human being could move through a wormhole, since it would theoretically be narrower than an atom and it would tend to disappear the instant it formed.
Superconductivity
According to the prominent scientist in this country V. L. Ginzburg the latest world achievements in the field of superconductivity mean a revolution in technology and industry. Recent spectacular breakthroughs' in superconductors may be compared with the physics discoveries that led to electronics and nuclear power. They are likely to bring the mankind to the threshold of a new technological age. Prestige, economic and military benefits could well come to the nation that first masters this new field of physics. Superconductors were once thought to be physically impossible. But in 1911 superconductivity was discovered by a Dutch physicist K. Onnes, who was awarded the Nobel Prize in 1913 for his low-temperature research. He found the electrical resistivity of a mercury wire to disappear suddenly when cooled below a temperature of 4 Kelvin (-269°C). Absolute zero is known to be 0 K. This discovery was a completely unexpected phenomenon. He also discovered that a superconducting material can be returned to the normal state either by passing a sufficiently large current through it or by applying a sufficiently strong magnetic field to it. But at that time there was no theory to explain this.
For almost 50 years after K. Onnes' discovery theorists were unable to develop a fundamental theory of superconductivity. In 1950 physicists Landau and Ginzburg made a great contribution to the development of superconductivity theory. They introduced a model which proved to be useful in understanding electromagnetic properties of superconductors. Finally, in 1957 a satisfactory theory was presented by American physicists .which won for them in 1972 the Nobel Prize in physics. Research in superconductors became especially active since a discovery made in 1986 by IBM scientists in Zurich. They found a metallic ceramic compound to become a superconductor at a temperature well above the previously achieved record of 23 K.
It was difficult to believe it. However, in 1987 American physicist Paul Chu informed about a much more sensational discovery: he and his colleagues produced superconductivity at an unbelievable before temperature 98 К in a special ceramic material. At once in all leading laboratories throughout the world superconductors of critical temperature 100 К and higher (that is, above the boiling temperature of liquid nitrogen) were obtained. Thus, potential technical uses of high temperature superconductivity seemed to be possible and practical. Now some scientists are trying to find a ceramic that works at room temperature. But getting superconductors from the laboratory into production will be no easy task. While the new superconductors are easily made their quality is often uneven. Some tend to break when produced, others lose their superconductivity within minutes or hours. All are extremely difficult to fabricate into wires. Moreover, scientists lack a full understanding of how ceramics become superconductors. This fact makes developing new substances largely a random process. This is likely to continue until theorists give a fuller explanation of low superconductivity is produced in the new materials.