时间旅行在理论上是可以实现的。爱因斯坦创立的相对论将空间和时间联系在了一起，相对论提出，如果你以接近光速的速度从地球向太空飞去，那么在返回地球时，你将可以到达 “未来”。然而，要想 “穿越” 到过去则困难得多，不过理论上是有一种方法可以帮人类实现这个愿望，即通过 “蠕虫洞” 穿越时空，但目前尚无证据表明蠕虫洞确实存在。本文探讨时间旅行的可能性。

词汇：time travel 时间旅行

If you could time travel, would you visit the past or the future? You could find your ancestors, descendants, or experience life when dinosaurs roamed your back garden. It sounds otherworldly, but scientists have looked into whether time travel is actually possible.

Albert Einstein's theory of relativity revolutionised understanding of space, time, mass and gravity. The key element of this theory is that time and space are linked together, and time doesn't flow at a constant rate, meaning it speeds up or slows down, depending on where you are. For example, when you travel at high speeds, time decreases, which means, according to NASA, astronauts in space age more slowly than those on Earth! So, if you wanted to travel to the future, you would need to move close to the speed of light. Then, while centuries pass on Earth, you'd experience a relatively short amount of time and could hypothetically return home, where it would be the future!

Travelling backwards in time seems much more difficult. Theoretically, one way of going back is via a wormhole. That means, if space and time can be folded like paper, we could create a tunnel – a shortcut between points in time. The problem is that there is no evidence that wormholes exist. "It's been shown mathematically that they can exist, but whether they exist physically is something else," says Emma Osborne, an astrophysicist at the University of York. Also, theories show that wormholes would be so small that a person definitely couldn't fit through one, and they would have such an intense gravitational field that they would collapse very quickly.

For now, it seems we'll have to be content with science fiction and using telescopes to look back in time rather than travelling through it.

词汇表

ancestor 祖先
descendant 后代
otherworldly 超脱尘俗的，非现实世界的
theory of relativity 相对论
mass 质量
gravity 重力，引力
flow （时间）流动，流逝
speed up 加速
slow down 减速
age 变老
the speed of light 光速
century 一百年，世纪
wormhole 蠕虫洞
shortcut 捷径，近路
astrophysicist 天体物理学家
gravitational field 引力场
collapse 崩塌，坍塌
science fiction 科幻小说
telescope 望远镜

测验与练习

1. 阅读课文并回答问题。

1. True or False? Time flows at the same speed across the universe.

2. How fast would you need to move to travel to the future?

3. True or False? It is easier to travel to the future than the past.

4. How would a wormhole help you to travel in time?

5. What are three problems with using wormholes to travel to the past?

2. 选择意思恰当的单词或词组来完成下列句子。

1. Don looked much older than when I last saw him – he's really _______.

aged time travelled flown sped up

2. When she saw the cyclist in the road, she _______ to avoid a collision.

slow down collapse slowed down collapsed

3. The road is a _______. If you use it, you'll cut your journey time by five minutes.

shortcut century telescope gravity

4. I found _______ who worked as a scientist when researching my family tree.

astrophysicist a descendant an ancestor mass

5. Is that animal real? It looks like something from _______!

flow gravitational field wormhole science fiction

答案

1. 阅读课文并回答问题。

1. True or False? Time flows at the same speed across the universe.

False. Time doesn't flow at a constant rate, meaning it speeds up or slows down, depending on where you are.

2. How fast would you need to move to travel to the future?

If you wanted to travel to the future, you would need to move close to the speed of light.

3. True or False? It is easier to travel to the future than the past.

True. Travelling backwards in time seems much more difficult.

4. How would a wormhole help you to travel in time?

A wormhole could create a tunnel – a shortcut between points in time.

5. What are three problems with using wormholes to travel to the past?

There is no evidence that wormholes exist, they would be so small that a person wouldn't fit through one, and they would have such an intense gravitational field that they would collapse very quickly.

2. 选择意思恰当的单词或词组来完成下列句子。

1. Don looked much older than when I last saw him – he's really aged.

2. When she saw the cyclist in the road, she slowed down to avoid a collision.

3. The road is a shortcut. If you use it, you'll cut your journey time by five minutes.

4. I found an ancestor who worked as a scientist when researching my family tree.

5. Is that animal real? It looks like something from science fiction!