| Tom Siegfried: That black-hole feeling could be universal 04/09/2001 By / The Dallas Morning News Black holes are a lot like some jobs – once you're in, you're trapped, with no way to escape.
Of course, certain jobs do offer some flexibility, as long as you don't try to go too far. And if you lived inside a black hole, you'd be free to fly around inside, at least for a while. That's because all the mass that goes into making a black hole is crushed into a point in its center. The rest of a black hole's interior is relatively empty.
But gravity is so strong within that space that you could not get out of a black hole, no matter how fast you were able to fly. And sooner or later, you, too, would be sucked into its center like a subatomic strand of spaghetti.
Whether that happens sooner, or later, depends on the size of the black hole, and that depends on how much mass was crushed to make it. If you could magically compress all the mass of the Earth densely enough to make a black hole, it would be about an inch across. The mass of the sun condensed to black-hole size would make a ball only a few miles wide.
But take the amount of mass in the entire known universe and condense it enough to make a black hole, and you get a volume of space that's pretty close to the size of the entire known universe. And so, such a coincidence suggests, it may very well be that the universe itself is just a really big black hole embedded in some even bigger, unknown universe.
Scientists have speculated on this possibility for years, with no solid evidence to support it. But a new analysis describes some reasons for taking the idea seriously. If the universe formed inside a black hole living in a bigger, "parent" universe, certain mysteries about the big-bang birth of the cosmos might be easier to explain.
"Many of the problems of the standard big bang can be solved if the universe is created inside a black hole which is resting in a parent universe," write physicists Damien Easson and Robert Brandenberger of Brown University in Providence, R.I. "It is clear that the idea that our universe might be generated from the inside of a black hole is of great interest."
Such a cosmological Russian-doll scenario might help scientists understand why the known universe has some of the properties it does, the Brown physicists say in a paper appearing recently on the Internet (www.lanl.gov/abs/hep-th/0103019).
"A daughter universe spawned from the interior of a black hole resting in a mother universe ... will take on certain properties of the mother universe," they note.
Understanding this idea is a little tricky, because where black holes are concerned, space and time are not what they ordinarily seem. From the viewpoint of residents in the mother universe, for example, chunks of matter falling into a black hole reach its center at different times. But for occupants of the daughter universe inside the black hole, the chunks would seem to arrive at the same time, but in different places.
"With the same inevitability that an observer outside of the black hole must move forward in time, grow old and die, an observer inside the horizon can only move forward in 'space,' eventually reaching the center of the black hole," the physicists write.
So keep that in mind before you try to explain this to a friend. But if anybody asks, just say that the space-time switch is essential for making the math work out. And the math makes certain problems about the universe work out.
One problem in particular has vexed astronomers for decades – why is the universe so smooth? A cold glow of radiation found throughout space is almost perfectly uniform in temperature, indicating that matter was spread out evenly through space when the radiation was generated, 300,000 years after the big bang. But that was not enough time for stuff occupying that much space to get thoroughly mixed. (Mixing can't take place any faster than the speed of light.)
If the universe is a black hole sitting in a bigger universe, though, matter could have been thoroughly mixed on its way in from the outside, the Brown physicists suggest.
Another curious problem involves the information contained in objects that fall into a black hole.
Quantum theory, which has demonstrated utter infallibility since its invention, demands that all information – such as the way an object is put together – can be recovered from wherever it goes, at least in principle. If information falls into a black hole, though, it would seem to be irretrievably destroyed. But the problem is solved if the information simply reappears in a baby black hole living inside the bigger black hole.
"Information is transferred from the parent universe to the black hole interior universe," the scientists write.
Other problems about the nature of space can also be solved if the known universe is a mere babe of a bigger black-hole parent. So it just may be that no matter where you live or what your job is, your future is black.
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