霍金自我挑战“黑洞悖论”

After 29 years of thinking about it, Stephen Hawking says he was wrong about black holes. The renowned Cambridge University physicist formally presented a paper on July 14 arguing that black holes, the celestial vortexes formed from collapsed stars, preserve traces of objects swallowed up and eventually could spit bits out "in a mangled form."

Hawking's radical new theory caps his three-decade struggle to explain a paradox in scientific thinking: How can objects really "disappear" inside a black hole and leave no trace, as he long believed, when subatomic theory says matter can be transformed but never fully destroyed?

Hawking had previously insisted that black holes destroy all molecular fingerprints of their contents and emit only a generic form of radiation.

But at the 17th International Conference on General Relativity and Gravitation, Hawking presented mind-boggling new calculations that suggest black holes are able to cast out their contents - and that there's only one way in and one way out.

Hawking, 62, said he no longer believes a 1980s theory that black holes might offer passage into another universe, a rival explanation for identifying where matter and energy go when consumed by a black hole.

Hawking now sides with particle physicists who have long insisted that any matter swallowed by a black hole can't just disappear but must eventually generate a specific output. The latest theory offers hope that scientists one day may identify the history of what a black hole has taken in over the eons - by decoding what it emits.

"There is no baby universe branching off (inside a black hole), as I once thought. The information remains firmly in our universe," Hawking said in a speech to about 800 physicists and other scientists from 50 countries. "I'm sorry to disappoint science fiction fans, but if information is preserved, there is no possibility of using black holes to travel to other universes.

"If you jump into a black hole, your mass energy will be returned to our universe, but in a mangled form, which contains the information about what you were like, but in an unrecognizable state."

Hawking's new theory produced waves of skepticism and puzzlement from leading physics professors. Two in the front row - William Unruh of the University of British Columbia and Robert Wald of the University of Chicago - shrugged and shook their heads in disbelief as Hawking spoke.

"Hawking is completely revising his prior belief that what goes into a black hole is washed out. Now he believes that anything emitted from a black hole can be identifiable back to its source," said Wald, an expert on black holes. "He's running away from what we still believe."

Unruh said: "Part of the problem is he's providing so few details, so it's impossible to know whether we can believe these calculations. Stephen Hawking's not stupid, so we're going to take what he says seriously ... but the whole theory we're hearing seems extremely speculative."

[翻译]

经过29年的思考，斯蒂芬·霍金表示，他以前对黑洞的看法是错误的。7月14日，这位剑桥大学的著名物理学家正式发表了一篇论文，认为黑洞这种由星体残骸演化成的漩涡会保留被吞噬物体的痕迹，而且终将释放出少量“被撕碎”的物质。

霍金激进的新理论颠覆了他30年来为了科学地解释“黑洞悖论”而进行的努力：被吸入黑洞的物体怎样才能真正“消失”，不留一点痕迹呢？长期以来他一直是这样认为的，而亚原子理论认为物质的形式可以相互转换，但不可能完全消失。

此前，霍金坚持认为，黑洞会摧毁其中所包含的一切“微小信息”，然后只是正常向外辐射能量。

但是，在第17届国际广义相对论和万有引力大会上，霍金提出了令人难以置信的新的计算结果，认为黑洞能够将吞噬的物质慢慢释放出来，而且吸收和释放的方式都只有一种。

62岁的霍金说他不再相信20世纪80年代的理论，当时的理论认为黑洞可能可以通往另一个宇宙空间，这正好可以用来解释被黑洞吞噬的物质和能量去了哪里。

霍金现在站在粒子物理学家一边，长期以来，粒子物理学家们坚持认为任何被黑洞吞噬的物质都不会凭空消失，最后必然以一种特殊的方式释放出来。最新的理论让我们看到了希望：有朝一日，科学家们也许能够通过解析黑洞释放出的信息来确定黑洞长久以来的“吞噬史”。

霍金面对来自50个国家的大约800名物理学家和其他科学家发表了演讲，他说：“（黑洞里）没有我曾设想过的子宇宙分支，物质信息仍然牢牢地保存在我们这个宇宙里。我很遗憾这让科幻迷们失望了，但如果物质信息被保存了，（我们）就不可能利用黑洞去别的宇宙空间旅行。”

“如果你跳进一个黑洞，你的物质能量将以一种‘被撕裂'的形式返回到我们的宇宙中，其中包含你以前的信息，但是已经处于无法辨认的状态。”

霍金的新理论在物理学权威中激起了怀疑和困惑的浪潮。霍金在发表演讲时，其中的两位领军人物——英国哥伦比亚大学的威廉·翁鲁和芝加哥大学的罗伯特·沃尔德——不断耸肩摇头表示怀疑。

黑洞专家沃尔德说：“霍金完全改变了他自己以前的观点，霍金以前认为进入黑洞的一切都会被‘冲走'。现在他相信从黑洞释放出的任何物质都能追溯到来源。他已经偏离了我们仍然坚信的理论。”

翁鲁说：“部分问题在于他提供的详细证据太少，因此我们不可能知道这些计算结果是否值得相信。斯蒂芬·霍金并不傻，因此我们会认真考虑他的话……但我们所听到的整个理论似乎纯粹来自推理。”

vortex: 旋涡流，旋风
swallow up: 淹没，吞没
spit out: 吐出
cap: 覆盖，颠覆
mind-boggling: 难以置信的
eon: 永世，无数的年代
branch off: 分叉

（中国日报网站译）