时光旅行不再遥远？美科学家发表最新理论
时间：2010-06-12
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理论物理学家Ronald Mallett毕生都在为制造一台时光机这一使命而努力。他的时光机理论是基于爱因斯坦的相对论，涉及制造一个环型光束并利用这一能量产生一个巨大的引力场。
康涅狄格大学(University of Connecticut)理论物理系教授Ronald Mallett在日前举行的嵌入式系统大会(ESC)上发表了一篇关于时间穿越之物理学的充满神秘色彩的大会主题演说，描述了黑洞、蓝色巨人星、蠕虫洞(连接黑洞入口的隧道)等“宇宙中的一些奇怪的事”来说明(至少在理论上)将来某一天进行时光穿梭的可能性。
Mallett称，这一天的到来可能不会像人们认为的那么久。
时间旅行是人类最古老的幻想之一。但它真的能实现吗？我们大家都很好奇未来会发些什么事情，我们一直在思索这个问题，“如果我能回到过去，能改变过去人生中的一些事情么？” 我在这里告诉大家，我们正处在让时间穿越成为现实的门坎上，并且它在基于真实物理基础上。
《时间旅行者：一个科学家的个人使命让时间旅行成为现实》一书的作者，Mallett解释了在他刚刚十岁的时候，父亲意外受伤而逝世，H.G. Well的书《时间机器》使他立志要能及时回到过去挽救他父亲的生命。谢天谢地，我很聪明，并没有对别人讲起我的计划——他们已经够担心我了”。
这样的使命成为了他终生的职业，尽管Mallet表示，多年来，他用《黑洞》作为他的表面理由。“黑洞被认为是一个疯狂的想法，但是合情合理的疯狂。正是它帮助我在学术界生存，”他说。“直到我拿到终身教职，成了一个全职教授，我才从时间穿越的壁橱里走出来(才公开宣布这一想法)。”
现在其它理论物理学家都在关注时间穿越，他说，大家一起努力工作以验证他的理论，Mallett的理论基于爱因斯坦的相对论。allett做了大量令人倾佩的工作来解释这一理论，Mallett在没有用到数学，并且不到10分钟的时间揭示了利用光来操纵时间的实际可能性。或许这对现场主要是工程师的观众有帮助。
Mallett沉思道，这对19世纪通过实验发现光速是恒定的的科学家而言，感觉该是多么不可思议。
要保持光速减慢，唯一方法就是改变另外的东西，所谓另外的东西就指的是“时间”——必须慢下来，过去的实验证明了这一点。Mallett讲述了1971年由美国海军天文台进行的一次实验，在此次实验中，保持一个原子时钟静止，而另一个原子时钟被放在一架普通的喷气式客机上，这架飞机以音速在世界各地飞行。最后客机上时钟变慢——它减慢的时间和爱因斯坦所预言的一模一样。
根据爱因斯坦的理论，引力也会使时间变慢。Mallett指出，在座的每个人都应熟悉这种现象。他描述了早期的GPS系统为何不能正常工作的原因，那是因为工程师们没有考虑到基于地面的单元运行明显要慢于卫星上的时钟。“实际上他们要用爱因斯坦的理论来纠正这个问题。”
Mallett指出，由于黑洞存在强大的引力，它可被用作一类天然的时光机，尽管在这一过程你会被撕成碎片的事实不会让人感到愉快。
Mallett的时间机器是基于一个环形激光器的机器，它可能是一个更实际的方案。据Mallett解释，他的时光机理论涉及创造一个回旋光束。这一能量会产生一个引力场，可以实现时间穿越。Mallett目前正在寻求资金援助以进行更多实验。
Mallett最后总结承认，虽然他认为，我们在技术上真正地处在时间穿越的门坎上，认识到这一点很重要只有到这一刻才真正有意义。他最后总结，希望大家都能享受各自的人生旅程。
(参考原文：ESC Chicago keynoter makes case for time travel，by Karen Field)
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ESC Chicago keynoter makes case for time travel
Theoretical physicist Ronald Mallett is on a lifelong mission to build a time machine. His theory of a time machine, based on Einstein’s Theory of Relativity, involves creating a circulating beam of light and exploiting the energy to produce a gravitational field.
by Karen Field
Theoretical physicist Ronald Mallett is on a lifelong mission to build a time machine. His theory of a time machine, based on Einstein’s Theory of Relativity, involves creating a circulating beam of light and exploiting the energy to produce a gravitational field.
Ronald Mallett, a professor of theoretical physics at the University of Connecticut, gave a mind-bending keynote speech on the physics of time travel to an enthralled audience at the Embedded Systems Conference here Tuesday morning, describing how black holes, blue giant stars, and worm holes (tunnels that connect the mouths of black holes)—some of the strangest things in the Universe—illustrate (at least in theory) the potential for time travel some day.
And that day, Mallett claimed, is not so far in the future as one might think.
“Time travel one of mankind’s oldest fantasies. But is it really possible? All of us have wondered what’s going to happen in the future, and we’ve contemplated the question, ‘What if I could back and change something in my past?” said Mallet. “I am here to tell you we are on the threshold of making time travel a reality, and it’s based on real physics.”
Author of “Time Traveler: A Scientist’s Personal Mission to Make Time Travel a Reality,” Mallett explained how the trauma of his father’s unexpected death when he was just ten and H.G. Well’s book The Time Machine set him on a mission to travel back in time and save his father’s life. “Thankfully, I was astute enough not to tell other people about my plan—they were already worried about me,” Mallett .
That mission became a lifelong preoccupation, though Mallet says that for many years he used “black holes” as his cover story. “Black holes were considered a crazy idea, but legitimate crazy. That’s what helped me survive academia,” he said. “It wasn’t until I got tenure and was made a full professor that I came out of the time travel closet.”
Now other theoretical physicists are looking at time travel, he said, and people are working with him to verify his theories, which are based on Einstein’s Theory of Relativity. Mallett did an admirable job explaining the theory, which shows the real possibility of using light to manipulate time, with no math and in less than ten minutes. Possibly it helped that the audience was mainly engineers.
How weird it must have been, he mused, for 19th century scientists to discover through their experiments that the speed of light was constant.
“The only way that speed of light can stay the same is that something else has to be altered. That something else is time—it has to slow down, as experiments have shown,” he said. He described a 1971 experiment conducted by the Naval Observatory, in which one atomic clock was kept stationary, and another atomic clock was put on an ordinary passenger jet and flown around world at the speed of sound. The clock on the passenger jet had slowed down--it had lost time exactly way Einstein had predicted.
According to Einstein’s theory, gravity will also cause clocks to slow down. Mallett pointed out that everyone in the room was familiar with the phenomenon. He described how early GPS systems did not work properly because engineers failed to take into account that the ground-based units were running noticeably lower than the clocks onboard the satellite. “They actually had to use Einstein’s theory to correct the problem.”
Because of the strong gravitational force associated with a black hole, Mallett pointed out that it could be used as a kind of natural time machine, though the fact that you’d be ripped apart in the process might not be so pleasant.
Mallett’s time machine, based upon a ring laser’s properties, may be a more practical approach. His theory of a time machine, he explained, involves creating a circulating beam of light. The energy would produce a gravitational field, which could then be exploited to produce a mechanism for time travel. He’s currently seeking funding for further experiments.
He concluded by acknowledging that although he believes we truly are on the threshold of time travel technically, it’s important to realize that it’s only the moment that counts. “I want you all to enjoy your journey through time,” he concluded.
