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1 Introduction

1-1 Space-Time
Three numbers, called coordinates, are used to describe a position in space.   Four coordinates are used to describe an event's position in space-time.

1-2 Curved Space-Time
According to Albert Einstein's general theory theory of relativity, an object's gravity warps the space-time around it into the fourth dimension.

1-3 What is a Black Hole?
A black hole is like a giant vacuum cleaner in space, sucking in matter and compressing it to zero size and infinite density.   The boundary of a black hole is called the event horizon.

1-4 The History of Black Holes
Only dense, massive objects form black holes.   If a star has more than 3.2 times the mass of the Sun, gravity will win over the atomic energy pushing the star out, and the star will collapse completely.

2 Singularities

2-1 What is a Singularity?
A star continues to collapse to form a "singularity" of infinite density. Anything falling into the black hole would come to an end of time and be crushed to infinite density at the singularity.

2-2 Naked Singularities
A naked singularity, a singularity without an event horizon around it, would be a breakdown in the laws of physics.

3 Kinds of Black Holes

3-1 Non-Rotating Black Holes
Any non-rotating star will end up after gravitational collapse as a perfectly spherical black hole, whose size will depend only on its mass.  The rapid movements in the star's collapse would make it perfectly spherical.

3-2 Rotating Black Holes
Rotating black holes rotate at a normal speed. Their size and shape depend only on their mass and how quickly they are rotating.  The black hole may bulge at its equator.

3-3 Electrically Charged Black Holes
Adding electric charge forms a second event horizon.  As more charge is added, the inner event horizon gets larger and the outer horizon shrinks.

3-4 "Mini" Black Holes
"Mini" black holes could have been formed in the aftermath of the Big Bang.  A mid-air explosion in Siberia could have been caused by the impact of a very small black hole.

3-5 Galactic Black Holes
Scientists believe that gigantic black holes inhabit the cores of most galaxies.  Gravity drives gas and stars to the core, and they form a black hole.   Such black holes often have large accretion disks and "jets."

4 How Do You Find a Black Hole?
Scientists find black holes by looking for their effects on the surrounding matter.  Black holes are often found in binary star systems, where only one star is visible.  Cygnus X-1 was detected by the x-rays it gave off.

5 Exploring a Black Hole
Light coming into a black hole would appear redshifted.  Also, time slows down in the presence of strong gravity.  Time stops completely at the event horizon.  Things appear this way through the eyes of an outside observer.

6 Black Holes Ain't So Black!
Stephen Hawking suggested that virtual particles might caused a black hole to slowly lose mass.  Eventually, a black hole might cease to be a black hole and then explode with tremendous force.

7 Wormholes
Wormholes are like black holes, except their mouth is two-way.  They connect two points that are far apart with a short tunnel through hyperspace.  Time travel may also be possible through a wormhole.

8 White Holes
A white hole is the opposite of a black hole.   It's like a cosmic gusher.

9 Black Holes Proven by Hubble Telescope
The Hubble Space Telescope detected an accretion disk at the center of M87, using the Doppler effect to tell it was spinning.  The object weighs about 3 billion solar masses, and thus could only be a black hole.

Black Holes FAQ

Credits and Thanks

Bibliography

Image Usage Notices/Disclaimers
Here the team will display any usage notices or disclaimers for any of the above images where no permission was required (this is what allowed us to use them), as well as any other special notices regarding the images.

Personal Thanks
Here team members will thank everyone and everything that made this web site possible.

Photo and Illustration Credits
Here the team will tell where each and every picture used in this web site came from, and who owns the copyright (whether it be the team or someone else).

Fictional Media Containing Holes
(Black Holes, Wormholes, and White Holes, that is)

Glossary

Quiz Games