Science: Black Holes

It wasn't all that long ago that black holes existed only in the realm of theory, a space- and mind-bending musing of Albert Einstein, who posited the existence of objects in the universe so dense that even light could not escape them. Even after scientists began to accept several decades ago that these extremely exotic and powerful objects were not the stuff of science fiction, they still knew virtually nothing about them.

Over the past 10 years, however, black holes have moved to the center of the world of astrophysics, leading to a steady flow of discoveries that have begun to answer, or at least better describe, some of their mysteries. Read more of the story here: Scientists Shining Light Into Black Holes

Washington Post science writer Marc Kaufman, who covers space and NASA, was online to discuss this article on Monday, Jan. 8 at Noon ET.

A transcript follows.

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Marc Kaufman: Hello everyone. Lots of questions in the queue, so let's jump in (as it were.)

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Arlington, Va.: I've often wondered what happens to a black hole after it consumes all the material in the galaxy where it lives. I realize this would take millions of years to occur. Would the black hole still exist in darkness, searching for new stuff to devour, or would the black hole no longer have a gravity/ energy source and release all it's material into space?

Marc Kaufman: Good question, and one that hits on what I (and I think many others) find so fascinating about the subject of black holes. The answer, I believe, is that nobody really knows, though many have theories. This is such an exciting time regarding black holes because those theories can now be tested in ways that are new and exciting. Whether instruments will ever be developed to answer this question, however, is unclear. Some theorize that the gravity/energy of a black hole can burn out, others say that if a black hole resolves down to a "singularity" with near infinite mass and no volume, then it would never disappear.

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Reston, Va.: Hi,

As I understand it, if a black hole is massive enough, the gravity tides at the edge of the event horizon would be negligible so a person (in a spaceship) could enter inside without being ripped apart. From the point of view of any outside observers, the craft would be going slower and slower, and then appear to freeze until the end of time. By the time the universe ceases to exist (assuming it's not eternal), the spaceship would still appear to be outside the event horizon.

So my question is, from the point of view inside spaceship, would it ever actually make it inside the event horizon, or would it cease to exist in an instant along with the ouside universe?

Thank you,

Marc Kaufman: Fascinating to speculate about. But we do know in addition to all the other massively powerful aspects of black holes--the disc, for instance, spins at unimaginable speed--they also create extremely great heat. In other words, the spaceship would not have a good day at all.

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Gaithersburg, Md.: How do black holes change over time in terms of size? For instance, do they shrink, expand or disappear? If so, what would happen to the light and matter trapped within? Thanks.

Marc Kaufman: Cosmologist and astronomers say that black holes definitely can grow and shrink in size. With increased observation, they are finding that there are different kinds of black wholes, and that they most likely behave differently. Some, for instance, are born of dying stars, some grow as they collide with other black holes and or super-dense neutron stars, some may well be involved in the formation of galaxies. A very exciting aspect of black hole research centers around the fact that it is becoming more likely that most (all?) galaxies have a black hole at their center. This would certainly suggest they are implicated in their formation.

As to the question of what would happen to matter or light inside a disintegrating black hole, any answers now would lie in the realm of theory.

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San Diego, Calif.: I'm curious about the picture that accompanied your article. How much of that image is based on real data, and how much is artistic rendition?

washingtonpost.com: Scientists Shining Light Into Black Holes ( Post, Jan. 8)

Marc Kaufman: The NASA-generated image is definitely not an exact, or even inexact, representation. Instead, it tries to convey some of the best (bu still quite early) thinking about how a black hole might operate.

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Washington, D.C.: I seems the bigger a black hole becomes the stronger it becomes. So why doesn't the whole universe just get sucked up by them?

Marc Kaufman: The universe is characterized by gravitational pulls and forces of all kinds, and they act as counterbalance to the pull of the black holes. The line where the different forces meet--as it were--is called the event horizon, and that is where the dynamics get played out.

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Springfield, Va.: Marc -- In response to the questioner from Reston: For the person in spaceship, they will enter the black hole in finite time as seen by themseves. It is also interesting to note that as new material is added to the black hole, it will expand and come to include the spaceship in finite time as seen from the outside.

Let's just say that black hole thoery is exceedingly weird in respects like this.

Marc Kaufman: Thanks...

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DeKalb, Ill.: Wouldn't a black hole formed in a particle accelerator be dangerous? Would a small enough black hole be controllable?

Marc Kaufman: The researchers at the CERN super-accelerator say that any possible creation of something approaching a black hole would indeed be controllable. This massive particle accelerator is being assembled in a tunnel at the Swiss-French border, and will be turned on sometime this year, though full operations won't begin for a while after. It will do many of the things that the planned Texas super-collider would have done, and more. Many American physicists remain disappointed that the U.S. effort was cancelled, but we have constributed substantial sums to the CERN effort.

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Washington, D.C.: Okay, I'm trying to imagine a black hole the size of our solar system, almost infinitely dense, spinning at 950 times per second. Mmmm. Nope. Can't do it.

Marc Kaufman: I can't either. That's why this kind of research is so fascinating -- it stretches our minds (just as it stretches spacetime.)

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Baltimore, Md.: With one-third of the world's people who do not have clean water and food, would it not be better to spend the billions of dollars annually to improve the life on this planet?

The U.S. is the only country that pays its farmers to burn their surplus crops at the end of the growing season. Can't NASA create a shuttle to send food supplies to the world's starving children? It has to be cheaper to fly to Asia than to Pluto.

Or perhaps we can send all the world's politicians to the core of a black hole and see if they can report their findings?

Marc Kaufman: A reasonable question, and virtually everything that NASA does is indeed "discretionary." But I strongly believe that this is generally money very well spent in that it enriches our lives and serves to feed society's hunger for knowledge. The NASA science budget is about $5 billion a year -- not chump change, but hardly a major cost when compared to others. (Wasn't last year's supplementary appropriation alone for Iraq/Afghanistan in the $80 billion range.) Given the remarkable successes coming from the NASA science program -- from Hubble, from the Cassini probe to Saturn, from the remarkable Mars rovers that have lasted years beyond what was expected -- it seems to me tht it's generally worth the money.

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Washington, D.C.: Although I believe that the search for knowledge is generally a noble pursuit, something that inspires us and reignites our wonder of the universe, is there anything that we can learn from their study that you can envision as being immediately useful or practical for mankind?

Marc Kaufman: NASA often struggles to connect its work to technological advances that are of use, and there have indeed been some successes--such as GPS, satellite-based communications and the like. There is also a national security aspect to NASA research; work on close-in asteroids could, someday, tell us that a dangerous object is headed our way early enough that we might do something about it. But when it comes to black holes and cosmology, I think the value is not going to be practical but, as you say, in the search for knowledge.

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Anonymous: I know this may seem well out of the realm of possibilitiy. But when looking at a picture of a black hole, are there pieces of matter spewing from the very center, jets of matter if you will? Does this make the possibilities of connecting black holes a possibility, being sucked in in one black hole and spewed out of one millions of light years away?

Marc Kaufman: There has been some speculation that black holes could meet, as it were, and matter from one could empty into the other. But no observations have been made to give any support such an idea, as far as I know.

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Washington, D.C.: So the spinning black hole the size of our solar system: are its edges spinning at something significantly faster than the speed of light, or is space-time so warped in a black hole that it only appears that way us people out here in the "normal" universe?

Marc Kaufman: The spin at the event horizon is indeed very fast, but not beyond the speed of light. It's the enormously strong gravitational force inside the object that keeps light from escaping.

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Silver Spring, Md.: Article says, ... particles moving at 175 mph. Is that right or is is miles per sceond?

Marc Kaufman: Definitely miles per second. Our bad...

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Washington, D.C.: I understand that nothing escapes from black holes but isn't there some thought that black holes somehow return energy/mass through some sort of radiation happening right at the event horizon or maybe through some sort of funky extra-dimensional something or other?

Marc Kaufman: There definitely is a release of enormous energy/radiation at the event horizon--creating some of the brightest objects in the skies-- and there is a release of extremely powerful gamma rays when the black hole is formed. But the literature generally says that once the mass is pulled into the hole, it doesn't leave.

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Re : CERN: Sir, the CERN is a European institution (Conseil Europeen de Recherche Nucleaire) mainly sustained by the French. As the name implies, it has been maintaining a super accelerator for quite a time already such as the LEP (Large Electron Positron), I think that's one reason why the U.S. is also funding their new accelerator the LHC (Large Hadron Colllider)

Marc Kaufman: Thanks.

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Washington, D.C.: Do you envision us (the human race) one day using the power of a black hole as a source of energy, and if so how would you theorize that could be done?

Marc Kaufman: Definitely not. The closest ones are way too far away, and the energy is in forms that don't seem at all capturable.

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Warrenton, Va. : Richard Dawkins, in his best seller, "The God Delusion", poisits extending Darwinian evolution to cosmology. Citing the possibility of megaverses of which our universe is but one. He further states Black Holes as the potential sources of universes--perhaps our own universe being an example. Your comment.

Marc Kaufman: This is a fascinating topic, and one that inevitably flows from black hole theory and observation. Theory says that as black holes grow, they reach a point where particles are packed so tightly that they do not exist in space, though they have infinite mass. This point in space is called a singularity. In describing the origins of the Big Bang that is believed to have created the universe, physicists also speak of a singularity as the source. Pretty heady stuff...

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Washington, D.C.: The field interests me because I did a astronomy science fair project trying to explain what black holes were back in the early 1970s.

As smaller stars collapse to form dwarf stars or neutron stars (depending on masses), and larger stars collapse to nova, from where come super black holes which fill the center of galaxies?

Marc Kaufman: No real answers exist, but this is an area of great interest right now and much research. Are the black holes that appear to exist at the center of galaxies primordial -- going back to the beginning of time -- or are they created later and then become the embryo, or source, of a galaxy? Exciting to think that some day we may have an answer.

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175 MILLION mph: Actually, this is what the article said so it could be accurate, no?

Marc Kaufman: I guess as I approached the black hole, I was moving too fast as well.

Thanks for your many very good questions, and I regret that I will have to leave so many unanswered. But we'll return to the subject in the future.

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