Garbage Collection

§ [clip] Daily Clipping

Black holes turned 'inside out' (BBC)

ホーキング博士の件の発表のニュース。

Professor Hawking's new black holes never completely destroy everything that falls in. Instead, they continue to emit radiation for extended periods, and eventually open up to reveal the information within them.
"The black hole only appears to form but later opens up and releases information about what fell in, so we can be sure of the past and we can predict the future."

「 ブラックホールは最終的に開いて、落ちた物質の情報を開放する」

タイトルの "inside out(裏返る)"ってなんだ？これでは何も分からん。うーん。

GR17

Stephen Hawking (Cambridge)
The information paradox for black holes
The Euclidean path integral over all topologically trivial metrics can be done by time slicing and so is unitary when analytically continued to the Lorentzian. On the other hand, the path integral over all topologically non-trivial metrics is asymptotically independent of the initial state. Thus the total path integral is unitary and information is not lost in the formation and evaporation of black holes. The way the information gets out seems to be that a true event horizon never forms, just an apparent horizon.

こちらは、今回の発表が行われたInternational Conference on General Relativity and Gravitationのサイトに掲載されているホーキング博士の発表内容の概要。最後のところに「事象の地平線は本当には形成されず、見かけ上の地平線が形成されるだけである」と書いてありますね。その手前に書いてあることは私にはさっぱり分かりません。

Hawking: Black Holes Mangle Matter, Energy(ABCNEWS)

Famed astrophysicist Stephen Hawking said Wednesday that black holes, the mysterious massive vortexes formed from collapsed stars, do not destroy everything they consume but instead eventually fire out matter and energy "in a mangled form."
(中略)
Hawking's answer is that the black holes hold their contents for eons but themselves eventually deteriorate and die. As the black hole disintegrates, they send their transformed contents back out into the infinite universal horizons from whence they came.
Previously, Hawking, 62, had held out the possibility that disappearing matter travels through the black hole to a new parallel universe the very stuff of most visionary science fiction.
"There is no baby universe branching off, as I once thought. The information remains firmly in our universe," Hawking said in a copy of his speech distributed just before he appeared at the conference.
"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," he said. "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."

ABCニュースの記事。

「ブラックホールは全てを飲み込んでしまうのではなく、最終的には物質やエネルギーをmangled(バラバラの／引き延ばされた)形で開放する。ブラックホールが蒸発するに従って、飲み込まれた物質の情報は情報は我々の宇宙へ戻ってくる。ただし、その情報はmangled(バラバラになって／引き延ばされて)いるため、認識することはできない。今回の結果は、SFによくあるブラックホールが別の宇宙へつながっているという考えを否定するものだ。SFファンのみなさん、がっかりさせてごめんね。」

やっぱり、どういう理屈で情報が戻ってくるのかは分かりませんねえ。カンファレンスの後に配られたというホーキング博士のスピーチ原稿が読みたいなあ。

参考)ホーキング、また賭けに負ける(Junkyard Review)