王朝東

Fancy a trip down a wormhole？ Calculations suggest that this might be possible， because these entrances through space?time could stick around forever.

Wormholes are essentially a pair of connected black holes. Two types could theoretically exist. A non?traversable wormhole is like a room with two doors that can be used only from the outside—the doors are black holes through which things can enter， but never escape. “These are not very interesting， as any astronaut who is brave enough to venture in wont be able to make it back to tell the story，” says Diandian Wang at the University of California.

Traversable（能橫過(guò)的） wormholes are also possible， but until now we havent know whether they could exist for long enough for anything to pass through them. For such a wormhole to form， space?time needs to naturally change shape. In classical physics， this cant happen. But the rules of quantum mechanics （量子力學(xué)） allow space?time to do so for brief periods.

Wang worked on a scenario （設(shè)想） involving string theory， in which the fundamental ingredient of reality is tiny strings. If one of these strings breaks， it can create a traversable wormhole with black hole?like entrances at either end that allow both entry and exit.

Although researchers had shown that this was a possibility before， it seemed that the energy involved would always break the wormhole.

Now， Wang and his team have calculated that the curvature of space?time could counteract this acceleration， keeping the fake black holes still and allowing the throat of the wormhole to remain open. This scenario is extremely unlikely， and becomes even more unlikely. The longer the wormhole is and the larger the black holes are. Thanks to quantum mechanics， though， the probability of it happening isnt zero. Wangs team also calculated that， once a traversable wormhole exists， it could remain stable for at least as long as the universe has been around.

“The work shows how wormholes could be created from scratch，” says Aron Wall at the University of Cambridge. But he points out that they couldnt be used to time travel or move faster than light.

1. What are wormholes according to the text？

A. A pair of strings.

B. Rooms with two doors.

C. Real worm holes on the earth.

D. Tunnels through space and time.

2. What does “this” in paragraph 5 refer to？

A. The scenario.

B. The black hole.

C. The wormhole.

D. The calculation.

3. Which of the following supports Wangs scenario？

A. String theory.

B. Classical physics.

C. Modern research.

D. Quantum mechanics.

Difficult sentence

A non?traversable wormhole is like a room with two doors that can be used only from the outside—the doors are black holes through which things can enter， but never escape.

【翻譯】

【點(diǎn)石成金】這是一個(gè)主從復(fù)合句， A non?traversable wormhole is like a room with two doors是主句，that can be used only from the outside是關(guān)系代詞that引導(dǎo)的限制性定語(yǔ)從句，through which things can enter是“介詞+which”引導(dǎo)的限制性定語(yǔ)從句。