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 (, ; ) 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 distortion 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 apple and thus shorten the way considerably. A worm-hole in space is 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.
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3. key module 6. merely
. .
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b. activity full of risk, danger smth. is active and useful
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2. 12:
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1. between different countries
2. connected with one person or part of smth.
3. connected with one country
4. that supplies reliable information
5. of technology
6. of the state, government and politics
7. coming earlier in time
8. important because of possible danger
9. full of strong desire to be or to do smth.
10. broad, extending in various or all directions
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height, propelling force, wished, be greater than, pressing, what remains, force directed forward, remain in space at one place, spending or using, thrust without losses, braking, small (not serious or important).
Solar Sails
If we are going to open the solar system to rapid economic travel, we need to find advanced space propulsion systems. Solar sails may be among the keys to future interplanetary flights.
Solar sail propulsion uses large, lightweight reflectors attached to spacecraft that react to the light pressure from solar photons to obtain thrust. By tilting () the sail to change the force direction, the light pressure can be used to increase the orbital speed of the spacecraft, sending it outward from the Sun, or decrease its orbital speed, allowing it to fall inward.
A new type of solar sail, called a solar photon thruster, has a large sail that always faces the Sun for maximum light collection. The collector sail has a slight curvature () that focuses the sunlight down onto a much smaller sail, which redirects the sunlight to provide the net thrust vector desired. Besides being more efficient than a standard sail, a solar photon thruster can be launched at Shuttle altitudes. Standard sails can only operate above 1,000 km where the light pressure exceeds the atmospheric drag.
Were a solar sail made light enough, it could hover without orbiting, the light pressure from the solar photons balancing the gravity attraction of the Sun and/or Earth. Then it would be possible to use solar sails first for communication, broadcast, and weather satellites, second for scientific stations hovering over the Sun and the rest of the solar system, and third for transporting cargo to and from Earth, the planets, and asteroid belt without an expenditure of fuel.
