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Ask Super Mario . . .

In the following forum, questions posed by visitors to this Web site appear in plain text, while Mario Livio's answers appear in bold text.

Q: Dear Deepspace,
I was wondering, do you have any ideas on what is on the other side of a black hole? I read this book that said that there is a theory that a "white hole" exists on the other side of a black hole. Do you have any idea if that idea is true?
-- Anonymous

A: General Relativity permits such solutions as White Holes, which can be connectedto Black Holes by Worm Holes. However theories about these are, at present, quite speculative, and no known phenomenon requires White Holes as an explanation.

Q: Some time in the future could our sun become a black hole?
-- Anonymous

A: Our sun will not become a black hole. Only stars more massive than about 30 times the mass of our sun can become black holes. Our sun will eject its outer envelope and leave behind a white dwarf (which is about the size of the earth, but with a mass of almost that of the sun).

Q: Does anyone have any theories about what happens to matter when it is sucked into a black hole?
-- Ryan Thomas

A: Matter no longer exists in the form we know it, because even on the smallest scale particles are torn apart. At the singularity itself even space-time disappears.

Q: The show on Supernovaes and Black Holes was fascinating! I would like to know more about Black Holes. Specifically, if Black Holes gobble up everything in sight, including light, where does all of this stuff go once its been caught by this Black Hole? Does it get transported to some distant place in our universe? Does it go forward or back in time? Finally, any recommended shows or readings on the subject so I could find out more?
-- Mike Shultz

A: From the point of view of an external observer, matter disappears from view when it gets close to the "event horizon" of the black hole. Hence this matter is essentially lost from our universe. However, the mass of the black hole (and its area) increase, so this is felt through its gravity, and also through the effect on the total entropy (disorder) of the universe. The area of the black hole (like disorder) can only increase with time. There is a book on black holes in the Scientific American library series, it is by Begelman & Rees.

Q: 1) In the Black Holes that astronomers are studying there are Jet Streams of Fire being shot out at great distances. What are the chances that this could actually be some sort of recycling of matter as opposed to the release of energy toward the process of singularities.

2) How close must a Star be to effect us in the event that it explodes into Supernovae.

3) In the possibility of the event of the Big Crunch. How long in our time would or could it take, and would we notice it beforehand (Not that it would matter at that point). i.e.:Loss of sight of Quasars.
-- Brian Scully

A: 1) The jets are actually emanating from the centers of the accretion disks around the black holes. This is material that was on its way to be accreted, but is instead accelerated and collimated in the jet.

2) Supernovae in our own galaxy can be seen as stars even during daylight. A supernova may have triggered the collapse of the gas cloud which formed the solar system. There is no known massive star that is so near that it will actually destroy the earth as a supernova.

3) In order for a big crunch to occur, the universe would have to be contracting, hence we will notice that by seeing all the distant galaxies as blue shifted. In the final stages atoms will no longer exist.

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