Supermassive Black holes

Could it be that, like planets that clear out entire circular regions of a solar system from stuff like dust and asteroids, a black hole ultimately gobbles up all the stuff that, because it isn't orbiting fast enough, gets drawn in?

I'm thinking along the lines of binary stars--or even planets (Earth and Luna being nearly a binary planet)--that because of their relatively similar masses, continue to orbit one another but never collide.

And somewhere recently, I heard that information about a thing is not lost when it passes the event horizon of a black hole. (Something on NOVA or the Discovery channel, I think. These things come, I watch, say "wow!" and they go, and I forget when and where.)

PeeDee said:

I wish we could send probes into them and expect to retrieve data from them once they're past the event horizon.

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I think according to both Stephen Hawking and Ray Kurzweil, this is indeed possible, and it is probably the case that information is coming out of them....elsewhere or elsewhen. Grist for your fiction mill, no?

I've never heard of "dormant" vs. "active" black holes. They're not like volcanoes which may randomly (as far as we see on the surface) erupt. Black holes are like, well, holes in space, and nothing happens until and unless matter gets too near them. Then the matter gets accelerated big time, gas particles hit each other at high rates of speed, heating up and making light, x-rays and other electromagnetic radiation that we would see around a black hole (or we would see this "as" the black hole). It's all the bits of matter rushing in, approaching the speed of light and running into each other, that makes all the excitement of stuff around a black hole.

There's Hawking radiation, but it's insignificant except for very small (microscopic) black holes. These may have been created in the Big Bang, but would have evaporated away by now.

But that's mainly for "small" black holes, a few solar masses (that would be created in the collapse of a star just a few times larger than the Sun) or smaller (which would have been created in the Big Bang, or in more speculative ways). The huge black holes at galactic centers are so big that it may not look like much is going on. Sure, the stars are orbiting around the core at a pretty fast clip, but other than that... the gravitational tide is much, much lower, so you and your spaceship could be near or even into the event horizon and not even notice. Except it will take a long time to get back out, and you may eventually figure out that you're not ever gonna get out. Is that more comforting than the thought of approaching a smaller black hole, and getting literally torn apart by gravity that increases by thousands of G's for every foot closer you get?

My guess is that a black hole that is "dormant" means there's not a lot of matter in its vicinity that's falling into it, and "active" means there IS a lot of matter falling in.

Oh gosh! I used to be such a black hole geek ! I still love the space documentaries passionately, especially those with topics most people can't get their heads around X-D Quantum physics anyone? I might not get the maths but I can picture what's going on.

Who said science-fiction didn't teach you anything?

Oh yeah, that was my dad

Anyway, this is the first time I hear about dormant black holes. I must know proceed to torture the information out of google.

gclare said:

I think according to both Stephen Hawking and Ray Kurzweil, this is indeed possible, and it is probably the case that information is coming out of them....elsewhere or elsewhen. Grist for your fiction mill, no?

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Information that enters a black hole is indeed recoverable, perhaps in the form of Hawking radiation. Of course, such information is garbled beyond recognition.

I'm not quite sure what is meant by a "dormant" black hole. But as a black hole gets larger, the event horizon itself gets further from the "centre" of the black hole, so the gravitation forces become more diffuse. Or perhaps dormant black holes are such that they are evaporating (from the emission of Hawking radiation) faster than they are consuming more matter? I don't know.

PeeDee said:

Dormant black holes, as near as I can tell from articles such as this, are not actively pulling things in or excreting energy. They're just a well of gravity that isn't receiving any fuel. They are at the hearts of most galaxies, it's theorized, especially galaxies where stars are spinning too fast to be held together without the black hole at the center. Without it, they would just spin off into space.

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Ah, that makes sense.

Tachyon said:

Information that enters a black hole is indeed recoverable, perhaps in the form of Hawking radiation. Of course, such information is garbled beyond recognition.

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Right, but if I remember right, each of the guys I mentioned had thought of a way that it was not necessarily garbled beyond recovery...similar to the way you can have an ink spot in a vial of very thick, transparent fluid. You carefully stir the fluid clockwise three times, and the spot disappears. But when you stir three times counterclockwise, the spot is restored to its original appearance. Their ways probably included the creation of polarized comparison particles though, not untangling the original, tortured mess.

I thought this thread was about the song. Remarkably, as this forum is for writers, the group which sings it is called Muse.

PeeDee said:

I don't think it's lost, because I tend to think of black holes in the same sense as hurricanes and tornados. If you get inside, you're safer than on the outside edges of it. I realize this is probably wildly inaccurate, but that's where my mind goes.

I just wonder what happens to things inside. I mean, its not just SPACE tha curves toward black holes, it's TIME (how do they know this? That's something that fascinates me. How does time curve? How does a blakc hole curve time?)

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As a followup, I'm reading "Ripples on a Cosmic Sea: The Search for Gravitational Waves" (1998)- I'm skimming much of it because I've read so many other science and physics books (by John Gribbin, Roger Penrose, many others I forget at the moment, and even a "more recent" Brian Greene Superstring book) that a lot of it is already familiar to me, but he does give, among other things, a history of the developent of ideas of black holes, neutron stars, neutron binaries, supernovas and other fun astronomical things that almost surely generate (very weak and hard to detect) gravitational waves.

But to answer your question, I don't know that there's an explanation of "how", but the fact is "it happens." Any mass creates gravity, and gravity causes time to go slower, much like increasing speed toward the speed of light causes time to go slower for that thing whizzing by. Precise atomic clocks, one at sea level and one on a mountaintop, will run at measurably different rates because the Earth's gravitational force is less at the top of the mountain. The GPS sattelites in space have such clocks and they are being continuously compensated for the effects of how far they are from Earth and the speed at which they're orbiting.

The effect of time slowing down is much more pronounced near a black hole because the gravity (no pun intended, but glad I thought of it...) is so much greater.

The thing about black holes "preserving information" is a quite recent revelation. The idea is from the 1970's, but was settled (at least to SOME physicists' satisfaction) only a few years ago. It was easy for me to Google because I recall that Hawking lost a bet on this issue, and gave the winner a baseball encyclopedia. Here are a couple articles on it:
http://www.theory.caltech.edu/~preskill/globe-and-mail.html
http://en.wikipedia.org/wiki/Black_hole_information_paradox

PeeDee said:

I don't suppose you have a link where I can read about this ink spot business, which ALSO sounds fascinating.

(I'm in science-sponge mode. )

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Sorry PeeDee....I just tried to google various combinations. Nothing. But the good news is I now know how to remove a variety of stains from the carpet, and a few formulae for disappearing ink!

Here's a third page on the information coming out of a black hole by John Preskill, the winner of the bet and lucky recipient of the Baseball Encyclopedia:
http://www.theory.caltech.edu/~preskill/jp_24jul04.html

PeeDee said:

I don't suppose you have a link where I can read about this ink spot business, which ALSO sounds fascinating.

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Me too.

PeeDee said:

(I'm in science-sponge mode. )

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I've ALWAYS been in science-sponge mode, since perhaps age 5. I shudda been a scientist.

I love this thread

I loved the post about the speed of light. That is indeed fascinating.

Teach me more of the secrets and mysteries of the universe oh great masters!

Pthom said:

Could it be that, like planets that clear out entire circular regions of a solar system from stuff like dust and asteroids, a black hole ultimately gobbles up all the stuff that, because it isn't orbiting fast enough, gets drawn in?

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It appears that you are exactly correct here. Black holes go "dormant" once they've cleared out the neighborhood of stuff they can swallow. Which is not much different from the formation of stars, which essentially stop growing in their birth nebula once they've done the same thing. The sun isn't gobbling up appreciable amounts of material anymore because everything orbiting it is far enough away to be in stable, balanced orbital relationships. Same with black holes.

caw

The light we see is a radiation spectrum. It's a very narrow band approximately in the center of the electomagnetic spectrum, which extends from gamma radiation on one end, to radio waves on the other:



As I understand it, a black hole doesn't suck up only visible light, but electromagnetic radiation spectrum wide. I also understand that black holes emit (or eject) x-ray radiation in gigantic jets, but these are oriented along the axis of rotation, not in the plane where any orbiting planets might exist.

And that, folks, is about the extent of my understanding of black holes...except that they are, and no doubt will be for some time to come, great fodder for SF stories.

Hyperspace by Michio Kaku is facinating. He covers things like time warps, the 10th dimension, parallel universes, etc. Kinda mind blowing if you can actually understand it. Half of the time I can't. lol

PeeDee:
I mean, its not just SPACE tha curves toward black holes, it's TIME (how do they know this? That's something that fascinates me. How does time curve? How does a blakc hole curve time?)

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Space and time are the same thing. Some smart guys figured this out using math and a calculator. If you warp one, you warp the other, but warping one that we can readily observe -- space -- requires lots and lots of "energy." In this case, that energy is mass. (By the way, they "know" this merely in a theoretical sense. Right now, the math of the theory's component parts seems to hold up, suggesting it's true. Might find out otherwise later.)

PeeDee:
WHY does gravity affect time?

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Here's an analogy. Maybe a useful one, maybe not. (Though it should work in multiple ways, some of which may even be clearer than what I'll present here.) The analogy involves this diagram:

)--------)-------)------)-----) O)))))

Imagine that O above is an object speeding through air. Maybe a supersonic jet. It's moving from left to right. As it approaches supersonic speed, it compresses air in front of it. That's what these ))))) things are, compressed air. The farther-spaced things behind the O are normal air, uncompressed.

Imagine, now, that this thing is not a supersonic jet hurling through air, but is a supermassive body, say a black hole. And now imagine that everything on the right of it in the diagram above represents everything within its gravitational influence, and everything on the left remains outside that influence. It's the sheer crushing weight of the thing that squishes space around it just like a speeding jet squishes air ahead of it. Since space and time are the same, compressed space = compressed time. When we consider the left side of the graphic above, we see normal space, uncompressed space.

Also, note that the wee diagram above can be used to illustrate, in its own bad way, at least three of the Lorentz transformations: (1) space shrinks in the direction of motion (Lorentz contraction); (2) time slows down (time dilation); (3) clocks desynchronize (relativity of simultaneity or "sync shift"); (4) mass increases in the moving frame. (I forgot to add that these are how things appear to an observer in a fixed frame of reference when observing the moving frame of reference, as represented in the diagram).

I'd write more, but since I've been up since four this morning, this is all I can squeeze out of my brain. Heck, some of it may be remotely right. (Or it might embarrass me in daylight.)