Time travel is a familiar subject of science fiction and fantasy stories, from H.G. Wells to Rod Serling to Hot Tub Time Machine. But could time travel ever be possible in real life? And, if so, how would humans even handle a technology with such great capacity for destruction?从科幻作家赫伯特·乔治·威尔斯到编剧罗德·瑟林再行到科幻喜剧《热浴盆时光机》，时空旅行仍然是科幻小说和奇幻故事中熟知的主题。但时空旅行到底能否在现实生活中确实构建？如果知道可以构建，那么人类将如何处置一项享有如此极大破坏力的技术呢？Some scientists say time travel is theoretically possible, at least if you want to jump ahead to the future, but dont start saving up for a time machine just yet. As physicist Paul Davies explained for CNN in 2013, Over a century ago, Albert Einstein showed that time is intrinsically elastic, capable of being stretched or shrunk by motion.一些科学家指出，时空旅行从理论上是可以构建的，起码如果你想要去往将来还是可以的。但是也不要从现在开始就攒钱卖一台时光机。正如物理学家保罗·戴维斯于2013年在CNN中所说明的那样：“一百年以前，埃尔伯兹·爱因斯坦证明：时间从本质上来讲是具备弹性的，需要不受运动影响而拓展或膨胀。

”Essentially the closer youre going to the speed of light, the slower time moves. Fly to the star Vega, 25 light years away, and back again at 99% of the speed of light, and when you return to Earth in 2062, you will have experienced only seven years travel time in the spacecraft. In effect, you will have leaped 42 years into Earths future, Davies wrote.从本质上来讲，你的速度越是相似光速，时间移动地比较也就越慢。戴维斯写到：“假如你想飞到二十五光年之外的织女星，然后再以99%光速的速度返回地球。那么当你返回地球时，约早已是2062年了，这意味着相等于你在宇宙飞船内逗留7年的时间。

换句话说，你将横跨了42年的时间，回到了地球的未来时空。”So if you were to, theoretically, take a trip in a super-fast spaceship, you might feel (and look) as though only a few years had passed, but when you arrived back on Earth, decades would have passed and all your friends and family would be dead and gone. Time travel!从理论上来讲，如果你乘着超强较慢宇宙飞船去太空旅行，你可能会感觉到时间意味着过了几年。不过当你返回地球之后，实质上几十年早已过去了，你的家人或朋友很有可能早已不出人世了。这就是所谓的时空旅行！But what about going backwards? Could it ever be possible to pop back in time and stop bad things from happening and good people from dying? Theoretically, if you were to travel faster than the speed of light, you would be moving backwards in time, according to one hypothesis LiveScience reported.那么如果想返回过去呢？是不是有可能使人类返回过去，从而制止那些很差的事情再次发生，使那些心地善良的人们免遭丧生？根据《生活科学》中曾明确提出的一个假说，从理论上来讲，只有当你运动的速度需要打破光速，你才有可能引发时光倒流，返回过去。

But most scientists believe that nothing can actually travel faster than light, and, if you could go back in time, messing with the past would create all kinds of unsolvable paradoxes, like the Grandfather Paradox.但大多数科学家都指出，没任何物体的运动速度可以打破光速。并且，如果人类需要返回过去，和过去纠缠不清，就有可能引起一系列容易解决问题的问题和对立。比如“祖父悖论”。

Although some theories have attempted to propose workarounds for these inconvenient time-travel problems, it remains a pretty widely held belief that traveling backwards in time isnt possible for us humans. After all, as physicist Stephen Hawking said in his book A Brief History of Time, If time travel is possible, where are the tourists from the future?尽管一些理论早已尝试着为这些简单的时空旅行问题获取了一些替代解决办法，但大多数意见还是指出返回过去是人类不有可能构建的一个梦想。却是，正如知名物理学家斯蒂芬·霍金在他的《时间简史》中提及的那样：“如果时空旅行有可能构建，那些从未来来回到现今世界的旅行者们又在哪里呢？。

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