# What's behind a black hole? **URL:** \ **Category:** Factual Questions\ **Created:** [April 5, 2002, 3:53am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920 "2002-04-05T03:53:48Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Pyrokatt](https://avatars.discourse-cdn.com/v4/letter/p/ecc23a/32.png) [@Pyrokatt](https://boards.straightdope.com/u/Pyrokatt)\ **Post date:** [April 5, 2002, 3:53am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/1 "2002-04-05T03:53:48Z")
Hellooo, this is my first post. (of course I _had_ to make it about black holes šŸ˜ƒ ) Anywho, I was wondering - If a black hole really is sort of like a pothole in space, flat-ish, what would be behind it? I mean, if you think about it, a black hole would seem to be more of a black _ball_ than just a hole. Like, it would be taking in mass and whatnot from _all_ directions, I would think, but everyone always refers to it as a hole. Crap, I hope you get my drift because Iā€™m not explaining it very well. ---
**Author:** ![John\_Kentzel-Griffin](https://avatars.discourse-cdn.com/v4/letter/j/ccd318/32.png) [@John\_Kentzel-Griffin](https://boards.straightdope.com/u/John_Kentzel-Griffin)\ **Post date:** [April 5, 2002, 4:21am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/2 "2002-04-05T04:21:42Z")
It is called a hole because things fall into it. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [April 5, 2002, 4:21am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/3 "2002-04-05T04:21:42Z")
Welcome to the board. A black hole would either be a dimensionless point or spherical, depending on what part of it you are referring to. The singularity at the center is a dimensionless point. The event horizon is spherical (or very nearly so, I seem to recall that a spinning black hole is very slightly oblate, but I could be wrong). The radius of the event horizon is proportional to the mass of the singularity. More massive holes have larger radius event horizons. I think black hole is probably more convenient terminology than black ball though. People generally donā€™t think of stuff being about to dissappear into a ball. There isnā€™t really a good word in the english language for it though. They are unique in that stuff can go into them from every direction. Maybe you can suggest a name for a 3 dimensional hole. A ball-hole maybe? jk There is a new theory in town, though. Maybe ā€œblack holeā€ isnā€™t where its at after all. The gravastar is hip youngster on the block today. ---
**Author:** ![fluiddruid](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@fluiddruid](https://boards.straightdope.com/u/fluiddruid)\ **Post date:** [April 5, 2002, 6:04am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/4 "2002-04-05T06:04:12Z")
**scotth** , I have heard the idea of gravastars brought up several times on the board, but I confess I know little about the theory. Could you post a link to some information suitable for the layman? ---
**Author:** ![MarshalDowns](https://avatars.discourse-cdn.com/v4/letter/m/e56c9b/32.png) [@MarshalDowns](https://boards.straightdope.com/u/MarshalDowns)\ **Post date:** [April 5, 2002, 6:11am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/5 "2002-04-05T06:11:46Z")
Well, the way I always understood it was that a black hole was a infinitly collapsing body of extreme densityā€¦mass plays a less important part than densityā€¦ The event horizon is determined by the mass of an object, so any object, if it is compressed enough, can become a black hole if it becomes dense enough to fall within the event horizon. It is a proven fact that thousands of atom- sized- black holes are produced in our own atmosphere every day, simply becuse the particles in the solar wind collide with the particles in our atmosphere, which temporarily increases the density to a point inside the event horizon, which causes a black hole. These black holes only last for a fraction of a second,but they are black holes none the less. Incase you were wondering, event horizon is the sphere that signifies the boundry at which a speed faster than that of the speed of light is required to escape a source of gravity. And as we all know, nothing can reach the speed of light, except light itself, so in a black hole, nothing can escapeā€¦ Thatā€™s why it is called a black **HOLE** , because whetever goes in, cant get back outā€¦ not because of the shape of the point of gravity inside. Well, I think most, if not all of that is correct, If it isnt, please correct me! How do I learn these things!!! Iā€™m only 15 ya know! mabe I should just get a life.šŸ†’ ---
**Author:** ![John\_Kentzel-Griffin](https://avatars.discourse-cdn.com/v4/letter/j/ccd318/32.png) [@John\_Kentzel-Griffin](https://boards.straightdope.com/u/John_Kentzel-Griffin)\ **Post date:** [April 5, 2002, 6:44am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/6 "2002-04-05T06:44:14Z")
It is mass and volume that cause a black hole. For any given mass there is a critical radius, the Schwartzschild radius. If the mass is contained within a sphere of this radius, it will collapse to form a black hole. As the mass increases, the critical density actually decreases. It is a combination of mass and density that is needed to form a black hole. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [April 5, 2002, 12:34pm UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/7 "2002-04-05T12:34:21Z")
Also any black hole with a certain amount of angular momentum is assumed to be a ring singularity not a point. Which I would like to know can the event horizon be inside the ring? ---
**Author:** ![FriendRob](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@FriendRob](https://boards.straightdope.com/u/FriendRob)\ **Post date:** [April 5, 2002, 2:24pm UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/8 "2002-04-05T14:24:27Z")
> [@](#): > > \*Originally posted by MarshalDowns \* > \*\* > [snip] > It is a proven fact that thousands of atom- sized- black holes are produced in our own atmosphere every day, simply becuse the particles in the solar wind collide with the particles in our atmosphere, which temporarily increases the density to a point inside the event horizon, which causes a black hole. These black holes only last for a fraction of a second,but they are black holes none the less. > [snip] > \*\* This isnā€™t correct - although some theories propose that tiny BHs might exist, they have never been detected. > [@](#): > > \*\* > Well, I think most, if not all of that is correct, If it isnt, please correct me! > How do I learn these things!!! Iā€™m only 15 ya know! mabe I should just get a life.šŸ†’ \*\* OK, I did. The rest of it was quite correct. And science _is_ a life (well, part of one, anyway šŸ˜‰ ). Welcome to the boards. Glad to have you with us. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [April 5, 2002, 2:58pm UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/9 "2002-04-05T14:58:28Z")
> [@](#): > > \*Originally posted by fluiddruid \* > \*\ ***scotth** , I have heard the idea of gravastars brought up several times on the board, but I confess I know little about the theory. Could you post a link to some information suitable for the layman? \*\* [http://www.cnn.com/2002/TECH/space/01/21/black.holes/index.html](http://www.cnn.com/2002/TECH/space/01/21/black.holes/index.html) As an article for mass media news, this isnā€™t too technical. > [@](#): > > Which I would like to know can the event horizon be inside the ring? The minimum size for the event horizon will always surround the singularity. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [April 5, 2002, 4:35pm UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/10 "2002-04-05T16:35:35Z")
Hawkingā€™s work, though, suggests that quantum tunneling will sometimes permit a black hole to ā€œevaporateā€ ā€“ quite rapidly for the smallest ones ā€“ leaving behind a ā€œnaked singularity.ā€ What are the characteristics of a naked singularity? Well, start dividing every constant by zero, and quantify your results, and you have a pretty good handle on it. šŸ™‚ ---
**Author:** ![MarshalDowns](https://avatars.discourse-cdn.com/v4/letter/m/e56c9b/32.png) [@MarshalDowns](https://boards.straightdope.com/u/MarshalDowns)\ **Post date:** [April 5, 2002, 10:32pm UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/11 "2002-04-05T22:32:23Z")
Well thanks friendrob! Now that I think about it, no one has ever detected the tiny black holes, though they have been proved to be mathematically possible. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 6, 2002, 1:20am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/12 "2002-04-06T01:20:31Z")
Microholes[sup]\*[/sup] are mathematically possible, but just how easy they are depends on the model youā€™re feeding into the mathematics. One thing that we do know for certain, is that they canā€™t be formed using particle accelerators of the energy range weā€™re currently using. Well, itā€™s _possible_, but so incredibly unlikely that you might as well consider it impossible. Particles from the Sun are at lower energies than we can get in the lab, so theyā€™re also out of the question, but some of the most energetic cosmic rays might potentially be candidates. Unfortunately, itā€™s a lot harder to study cosmic rays than accelerator experiments, so we still havenā€™t seen any. - This depends on what you mean by ā€œmicroā€. Holes of atomic-scale radius are almost certianly possible, but holes of atomic-scale mass almost certainly are not. Nobodyā€™s quite sure what the minimum size would be for a black hole, but the most reasonable guess would be somewhere in the vicinity of the Planck mass and Planck length. The Planck mass is about the mass of a bacterium, much greater than an atom, whereas the Planck distance is about a millionth of a billionth of the size of a proton. ---
**Author:** ![MarshalDowns](https://avatars.discourse-cdn.com/v4/letter/m/e56c9b/32.png) [@MarshalDowns](https://boards.straightdope.com/u/MarshalDowns)\ **Post date:** [April 6, 2002, 1:40am UTC](https://boards.straightdope.com/t/whats-behind-a-black-hole/101920/13 "2002-04-06T01:40:10Z")
Cool thanksā€¦ Iā€™l just click the save button in my brainā€¦there we go!