Sample Scholarship Essays

Black Holes

.. stence. The singularity, to some scientists, is nature’s way of saying that the present physical laws we are using are not adequate to cope with the situation-perhaps we have missed the proper application of some existing laws or, in the extreme, because new laws are needed. Other scientists are just as certain that once we have a black hole, the singularity is ruled out; they indicate that as it takes an infinite time to reach the gravitational radius and as the universe spans a finite time, the black hole simply does not have enough time to go to a singularity. Perhaps an example will serve to illustrate what happens in space-time that could give rise to a singularity. Picture a thin sheet of rubber stretched over a large frame, and let us assume that this rubber represents a corner of the universe.

If we take a ball and place it in the middle of the sheet, the ball will sink into or depress the sheet to deform it. If we replace the ball with a heavier one and place it on the sheet, the ball will stretch the rubber more and the deformation will be greater, with the ball sinking deeper into the rubber. A still heavier ball will deform the sheet more and the ball will sink still farther into the rubber. Finally, if the ball had almost infinite weight and we assumed the rubber sheet could not tear, the ball would drop to an almost infinite distance from the frame Peters 6 supporting the rubber. And if at that instant the rubber sheet did open up a tiny hole, the ball might pop through the tiny hole to escape the sheet.

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With the escape of the ball, the pressure on the rubber would be relaxed and it would spring back to its initial position as a flat sheet. The gravitational stress would have been removed from space-time, but the ball would have effectively left our universe. Where would the ball be now? This situation has been deeply explored by many astronomers that we know of today.(Levitt 80-81) To return to our rubber sheet analogy, we can visualize a second rubber sheet directly under the first; as the black hole deforms the top sheet in some mysterious manner the bottom sheet is also deformed as a mirror image of the top. Or one can picture a softly inflated rubber balloon into which one is poking a finger. We will poke a finger in from the other side along a diameter. Now imagine a marble being pushed into the balloon by one of the fingers; the finger coming in from the other side of the balloon just touches it. Further imagine that the marble mysteriously passes through the two distended layers of the rubber.

When the pressure of the fingers is removed, the marble ends up at the other side of the balloon, diametrically opposite to the point where it was introduced. If we imagine the marble to be a black hole in this fashion, we have transferred it to another part of the universe. One serious drawback must be mentioned. At this time one cannot visualize an astronomer being compressed to the densities found within a black hole. However, this should not be considered an impossibility, for this concept possesses many fascinating overtones. One must remember that if we move with the speed of light, Peters 7 time literally stops, dimensions in the direction of motion shrink to zero, and mass becomes infinite. One cannot help concluding that an astronaut traveling at the speed of light would have zero dimension with infinite mass.

There is one difference –The singularity is a point while the astronaut becomes a line at the speed of light. Theory tells us that even though the astronaut was compressed to a line-this is what we on the outside world would see, if indeed it were possible to see him-the fast- moving astronaut would mot notice any difference in shape, motion, or time. This exposition gives rise to a most intriguing thought. Perhaps at some future date, by moving just within the gravitational radius, an astronaut may be able to move to another universe.(Levitt 93-94) Gravitational Collapse is the catastrophic fate that befalls a massive object when it’s gravity completely overwhelms all other forces. During most of a star’s lifetime, it’s tendency to contract as a result of it’s gravity is balanced by the outward pressure produced by the heat of it’s nuclear reactions. Eventually, however, the nuclear fuel will be exhausted. If the star’s mass is less than about 3 solar masses, it will eventually contract to a stable configuration as either a white dwarf (about the size of Earth but hundreds of thousands times denser) or a neutron star (a similar mass compressed into a sphere only a few miles across). More massive stars, however, will continue to shrink even further when their thermal and rotational energy is exhausted.

Unless the star sheds its excess mass, gravity will overcome all conceivable forces and gravitational collapse will occur. Once gravity exceeds the other forces, the star will fall in on itself in a few hours. Peters 8 When the size of the collapsing star falls below what is called the Scharzschild Radius, the escape velocity becomes equal to the light. When not even light can escape from the surface, the star is said to be inside a black hole. Theorems by Roger Penrose and Stephen Hawking show that, according to general relativity and similar theories of gravitation, a singularity or edge to the space-time continuum must occur.

It is believed, but has not been proved, that everything inside a black hole will hit the singularity and be utterly destroyed within a few microseconds; however, some claim that matter and energy may reappear in another universe. The collapse of a star or a dense cluster of stars can release large amounts of energy, perhaps 10% of the total rest-mass energy of the system if the collapse is nonspherical. Most of the energy will probably be emitted as gravitational waves. Matter falling into a black hole already formed can also release electromagnetic energy. This is a possible source of X rays from Cygnus X-1 in our galaxy and of visible light radio waves from quasars and from certain other distant galaxies.

The universe as a whole may also undergo gravitational collapse. The universe is presently expanding as distant galaxies move apart, but if they do no have escape velocity relative to each other they will eventually fall back together and bring the universe to an end. Whether this will happen depends on the density of matter in the universe, which is not precisely known.(Asimov 255) For the past couple of centuries astronomers have done many things to try to unlock the mystery of these natural wonders called black holes. The curiosity of many scientists has motivated them to use every means possible to do this. If there is Peters 9 one scientist who, in the last couple of decades, has contributed more towards this cause, it would probably be Ken Croswell.

He has had something to do with most of the major advances in this field of study. However, even with people like Croswell, our little world is still far from unlocking the mind-boggling mystery of black holes. Science.

Black Holes

Table of Contents
I.What are black holes?
II.Where do they come from?
III. Interesting facts about black holes.


IV. How are they discovered?
A. X-ray Emissions
B. Exotic Energy Sources
C. Star speeds
D. Masers
E. The Baseline Array
F. Hubble Telescope
G. Satellites
V.Quasi-Stellar Relations
VI. Locations
A. M87
B. Milky Way
C. Andromeda
D. ??????
E. NGC 6240
F. A0620-00
What are black holes? Black holes are the remains of a massive star that has collapsed and shrunk
to a tiny point in space. They have all of the gravity of the star concentrated into that point. Black holes
are difficult to see because they cannot be seen. They cannot be seen because they are spinning faster than
the speed of light and light cannot escape from them. They can be compared to a giant vacuum cleaner,
they suck in anything that gets near them.
Where do black holes come from? Black holes are formed when giant stars run out of fuel and are
overwhelmed by their own gravity. When this happens they cannot keep from collapsing. After stars
collapse, they start rotating and as they are
spinning, their gravity becomes stronger causing them to shrink. As the object becomes smaller, it starts
spinning faster and faster.

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Using a small black marble as an example of the size that Earth would become if it collapsed and
became a black hole, Todd R. Lauer, of the National Optical Astronomy Observatories said, ” Black holes
are very messy eaters. If you took that marble to an ‘all-you-can-eat buffet’ allowing it to consume all the
matter around it, the feeding frenzy would produce as much radiation as the Sun.”Research indicates that
black holes may have existed at the beginning of time. Black holes are so dense that not even light can
escape. Looking towards a black hole, the stars behind it would appear out of place because black holes
distort light. The immense gravitational pull of black holes is thought to be responsible for the swirling
masses of stars in spiral galaxies throughout the universe. Gravity in a black hole should be able to pack
stars in so tight that the intensity of the stars’ light would drastically increase towards the center of gravity.
Everything falling into a bla!
ck hole loses its identity, you couldn’t tell if it were a satellite or a T.V. set that fell in. Dr. Fred Chromey
of Vassar College in New York said, ” Black holes are the easiest way to explain some of the strange things
that are going on in some of the galaxies.”Research indicates that if a black hole formed, it would
eventually evaporate but it would take millions of years.


Earth’s escape velocity, the speed it takes to escape the pull of gravity, is 11 kilometers per second.
The escape velocity of a black hole is 300,000 kilometers per second, which is faster than the speed of
light. If Earth’s diameter shrank to less than 1 centimeter, the escape velocity would exceed the sped of
light, the escape velocity of a black hole. Anything can become a black hole if you compress it enough.


How are black holes located? Black holes technically can’t be seen, but they give off many clues
to their location. Signs of many black holes have been located during normal observation of other space
objects. Abnormally high levels of X-rays and gamma rays are the most common clues, but other exotic
energy sources are also good clues. Astronomers have also located black holes by studying the speeds of
swirling galaxies. If large objects are moving at very high speeds astronomers usually try to track their
orbits and try to locate a central object that could be the source of the gravity. Another clue to the location
of black holes are masers. Masers are the cosmic relatives of lasers. They are water molecules orbiting
black holes that capture and amplify radiation and send it back out into space. Masers are usually located
in the accretion disk, the swirling cloud of gases above a black hole. Some masers have been clocked
traveling over 650 miles per second.


Many types of equipment are used to locate black holes. One type of equipment is called the
Baseline Array. The Baseline Array consists of 10 radio dishes, each 82 feet across, spaced across a 5,000
mile area. It acts as one 5,000 mile wide telescope. The Baseline Array is so accurate the a user in Los
Angeles can read a newspaper in New York. Other pieces of equipment used are ‘orbiting observatories’
like the Hubble Telescope, which provided the first conclusive proof of black holes. Orbiting satellites are
also used to detect radio waves usually given off by black holes. The British satellite Ariel V discovered
the black hole A0620-00 this way.


Black holes may be related to the most exotic space phenomenon, quasi-stellar objects, most
commonly called quasars. Quasars shine so brightly that astrophysicists think the light must come from
superheated matter falling into a black hole. The leading theory about quasars says they may represent the
earliest period of evolution of galaxies. Quasars, so far, are the most distant objects known, some as far as
10 billion light years away.
Black holes are usually found in or near companion star pairs. One of the stars is sometimes a
dark star, a star that is hard to see or can’t be seen. Bruce Margon from the University of Washington-
Seattle says, ” We are finding that black holes come in a large number of sizes. Nature makes them like 50-
and 100-watt light bulbs.”Astronomers are finding that for reason, closer black holes are smaller than the
more distant ones. Black holes can be located by studying how they affect their surroundings.
A super-massive black hole has been located at the heart of Galaxy M87. It is between 2.5 and 3.5
billion times the size of our sun. The accretion disk at M87 is rotating at at least 1.2 million miles per hour.
Some people think that it might be a cluster of neutron stars, but it would take more than 2 billion stars to
get something that big. Anything that big in that small of an area would eventually collapse into a black
hole anyway.Superluminal jets, groups of high speed electrons which are flung out of galaxies thought to
contain black holes, have been detected coming out of M87. Superluminal jets can travel close to the
speed, but the fastest one has ever been found was going 93% of the speed of light.The frontier of the
M87 black hole is roughly the same distance that Uranus is from the Sun.
Superluminal jets in the Milky Way indicates a black hole is lurking nearby. Astronomers have
located something strange, near Sagittarius A* that is less than 1 million times the size of our sun, in the
Milky Way. This object doesn’t give off enough radiation to be a normal black hole. Scientists have
devised a model that would explain the lower radiation levels. The object is superheating the gases before
they enter. The heated gases move faster so less energy escapes. The model shows that the object can
consume 99.9% of the energy that is given off leaving .1% to escape, which would account for the low
energy levels.


A black hole smaller than the one in Galaxy M87 has been located near the center of the
Andromeda Galaxy, with a mass of only a few million solar masses. Near the center of the galaxy, there
are two star clusters, one bright the other faint. The bright cluster may be the nucleus of a dwarf galaxy
that Andromeda may have captured. The faint cluster is moving at a speed of over 850,000 miles per hour,
which is good evidence of a black hole. If Andromeda holds a black hole it would mean that there is a
black hole 50 times closer than the one in M87.


Another black hole was discovered in a galaxy less than 21 million light years from Earth. This
black hole has a mass of more than 40 million suns.


In Galaxy NGC 6240, almost 300 million light years from Earth, astronomers believe to have
found a black hole during observations of two colliding galaxies. The black hole is caught between the two
galaxies and is expected to merge with them in the next few hundred million years. It has a mass 10 to 100
times larger than any black hole ever found. It has the mass of the Milky Way in 1/10,000th the area. It
may have been left over from an early universe, or a quasar that has burned itself out. Its finding suggests
the presence of a lot of unobserved matter and it may be the first step in explaining dark matter or missing
mass. The object itself may be a form of dark matter, which makes up 90% of the mass of the universe.


In 1975 an X-ray burst and an optical nova lead to the discovery of a black hole. The black hole
A0620-00 is located in the constellation Monoceros. It is a dark object with a mass exceeding 3 solar
masses. It is part of a binary system, a pair of stars that orbit each other, consisting of an orange dwarf and
itself. Orange dwarfs are very common, in fact they make up more than 15% of star masses. The star is
orbiting the black hole. Astronomers have found that only half of the light comes from the star, the other
half comes from the accretion disk circling the black hole.


Black holes are much more common than astronomers once thought. Future research may locate
many more exotic phenomenon. Astronomers believe there may be thousands of black holes and other
mysteries of space, and they hope to learn more about them in the future.

References
Cowen, Ron. “Repaired Hubble Finds Giant Black Hole”
Science News, 145 (June 4, 1994) p. 356
Croswell, Ken. “The Best Black Hole in the Galaxy”
Astronomy, (March, 1992) pp. 30-37
Dye, Lee. “Evidence of Massive Black Hole Discovered by Astronomers” Los Angeles Times, (January
12, 1995)
p. A3+
Flamsteed, Sam. “99.9 Percent Sure”
Discover, 16 (January, 1995) p. 32
Kaiser, Jocelyn. “Does the Milky Way Hide its Black Hole?”
Science News, 147 (April 15, 1995) p. 230
Majeski, Tom. “Evidence of Second Black Hole Detailed”
Knight-Ridder/Tribune News Service, (May 31, 1994)
p. 0531K6533
Naeye, Robert. “Faster Than Light?”
Discover, 16 (January, 1995) p. 33
Sawyer, Kathy. Monstrous, Dark Stranger Seen in Neighborhood of Galaxy” Washington Post,
(April 10, 1991) p. A2
Sawyer, Kathy. “Scientists Detect 12 Black Holes”
Las Vegas Review-Journal+ Sun, (August 2, 1992) p. 21E
Shipman, Harry L. Black Holes, Quasars, and the Universe
Boston, Houghton Mifflin Company, 1980
Taylor, Ronald A. “Astronomers Spot Massive Mystery”
Washington Times, (April 10, 1991) p. A4






Black Holes
by



Table of Contents
I.What are black holes?
II.Where do they come from?
III. Interesting facts about black holes.


IV. How are they discovered?
A. X-ray Emissions
B. Exotic Energy Sources
C. Star speeds
D. Masers
E. The Baseline Array
F. Hubble Telescope
G. Satellites
V.Quasi-Stellar Relations
VI. Locations
A. M87
B. Milky Way
C. Andromeda
D. ??????
E. NGC 6240
F. A0620-00
What are black holes? Black holes are the remains of a massive star that has collapsed and shrunk
to a tiny point in space. They have all of the gravity of the star concentrated into that point. Black holes
are difficult to see because they cannot be seen. They cannot be seen because they are spinning faster than
the speed of light and light cannot escape from them. They can be compared to a giant vacuum cleaner,
they suck in anything that gets near them.
Where do black holes come from? Black holes are formed when giant stars run out of fuel and are
overwhelmed by their own gravity. When this happens they cannot keep from collapsing. After stars
collapse, they start rotating and as they are
spinning, their gravity becomes stronger causing them to shrink. As the object becomes smaller, it starts
spinning faster and faster.


Using a small black marble as an example of the size that Earth would become if it collapsed and
became a black hole, Todd R. Lauer, of the National Optical Astronomy Observatories said, ” Black holes
are very messy eaters. If you took that marble to an ‘all-you-can-eat buffet’ allowing it to consume all the
matter around it, the feeding frenzy would produce as much radiation as the Sun.”Research indicates that
black holes may have existed at the beginning of time. Black holes are so dense that not even light can
escape. Looking towards a black hole, the stars behind it would appear out of place because black holes
distort light. The immense gravitational pull of black holes is thought to be responsible for the swirling
masses of stars in spiral galaxies throughout the universe. Gravity in a black hole should be able to pack
stars in so tight that the intensity of the stars’ light would drastically increase towards the center of gravity.
Everything falling into a bla!
ck hole loses its identity, you couldn’t tell if it were a satellite or a T.V. set that fell in. Dr. Fred Chromey
of Vassar College in New York said, ” Black holes are the easiest way to explain some of the strange things
that are going on in some of the galaxies.”Research indicates that if a black hole formed, it would
eventually evaporate but it would take millions of years.


Earth’s escape velocity, the speed it takes to escape the pull of gravity, is 11 kilometers per second.
The escape velocity of a black hole is 300,000 kilometers per second, which is faster than the speed of
light. If Earth’s diameter shrank to less than 1 centimeter, the escape velocity would exceed the sped of
light, the escape velocity of a black hole. Anything can become a black hole if you compress it enough.


How are black holes located? Black holes technically can’t be seen, but they give off many clues
to their location. Signs of many black holes have been located during normal observation of other space
objects. Abnormally high levels of X-rays and gamma rays are the most common clues, but other exotic
energy sources are also good clues. Astronomers have also located black holes by studying the speeds of
swirling galaxies. If large objects are moving at very high speeds astronomers usually try to track their
orbits and try to locate a central object that could be the source of the gravity. Another clue to the location
of black holes are masers. Masers are the cosmic relatives of lasers. They are water molecules orbiting
black holes that capture and amplify radiation and send it back out into space. Masers are usually located
in the accretion disk, the swirling cloud of gases above a black hole. Some masers have been clocked
traveling over 650 miles per second.


Many types of equipment are used to locate black holes. One type of equipment is called the
Baseline Array. The Baseline Array consists of 10 radio dishes, each 82 feet across, spaced across a 5,000
mile area. It acts as one 5,000 mile wide telescope. The Baseline Array is so accurate the a user in Los
Angeles can read a newspaper in New York. Other pieces of equipment used are ‘orbiting observatories’
like the Hubble Telescope, which provided the first conclusive proof of black holes. Orbiting satellites are
also used to detect radio waves usually given off by black holes. The British satellite Ariel V discovered
the black hole A0620-00 this way.


Black holes may be related to the most exotic space phenomenon, quasi-stellar objects, most
commonly called quasars. Quasars shine so brightly that astrophysicists think the light must come from
superheated matter falling into a black hole. The leading theory about quasars says they may represent the
earliest period of evolution of galaxies. Quasars, so far, are the most distant objects known, some as far as
10 billion light years away.
Black holes are usually found in or near companion star pairs. One of the stars is sometimes a
dark star, a star that is hard to see or can’t be seen. Bruce Margon from the University of Washington-
Seattle says, ” We are finding that black holes come in a large number of sizes. Nature makes them like 50-
and 100-watt light bulbs.”Astronomers are finding that for reason, closer black holes are smaller than the
more distant ones. Black holes can be located by studying how they affect their surroundings.
A super-massive black hole has been located at the heart of Galaxy M87. It is between 2.5 and 3.5
billion times the size of our sun. The accretion disk at M87 is rotating at at least 1.2 million miles per hour.
Some people think that it might be a cluster of neutron stars, but it would take more than 2 billion stars to
get something that big. Anything that big in that small of an area would eventually collapse into a black
hole anyway.Superluminal jets, groups of high speed electrons which are flung out of galaxies thought to
contain black holes, have been detected coming out of M87. Superluminal jets can travel close to the
speed, but the fastest one has ever been found was going 93% of the speed of light.The frontier of the
M87 black hole is roughly the same distance that Uranus is from the Sun.
Superluminal jets in the Milky Way indicates a black hole is lurking nearby. Astronomers have
located something strange, near Sagittarius A* that is less than 1 million times the size of our sun, in the
Milky Way. This object doesn’t give off enough radiation to be a normal black hole. Scientists have
devised a model that would explain the lower radiation levels. The object is superheating the gases before
they enter. The heated gases move faster so less energy escapes. The model shows that the object can
consume 99.9% of the energy that is given off leaving .1% to escape, which would account for the low
energy levels.


A black hole smaller than the one in Galaxy M87 has been located near the center of the
Andromeda Galaxy, with a mass of only a few million solar masses. Near the center of the galaxy, there
are two star clusters, one bright the other faint. The bright cluster may be the nucleus of a dwarf galaxy
that Andromeda may have captured. The faint cluster is moving at a speed of over 850,000 miles per hour,
which is good evidence of a black hole. If Andromeda holds a black hole it would mean that there is a
black hole 50 times closer than the one in M87.


Another black hole was discovered in a galaxy less than 21 million light years from Earth. This
black hole has a mass of more than 40 million suns.


In Galaxy NGC 6240, almost 300 million light years from Earth, astronomers believe to have
found a black hole during observations of two colliding galaxies. The black hole is caught between the two
galaxies and is expected to merge with them in the next few hundred million years. It has a mass 10 to 100
times larger than any black hole ever found. It has the mass of the Milky Way in 1/10,000th the area. It
may have been left over from an early universe, or a quasar that has burned itself out. Its finding suggests
the presence of a lot of unobserved matter and it may be the first step in explaining dark matter or missing
mass. The object itself may be a form of dark matter, which makes up 90% of the mass of the universe.


In 1975 an X-ray burst and an optical nova lead to the discovery of a black hole. The black hole
A0620-00 is located in the constellation Monoceros. It is a dark object with a mass exceeding 3 solar
masses. It is part of a binary system, a pair of stars that orbit each other, consisting of an orange dwarf and
itself. Orange dwarfs are very common, in fact they make up more than 15% of star masses. The star is
orbiting the black hole. Astronomers have found that only half of the light comes from the star, the other
half comes from the accretion disk circling the black hole.


Black holes are much more common than astronomers once thought. Future research may locate
many more exotic phenomenon. Astronomers believe there may be thousands of black holes and other
mysteries of space, and they hope to learn more about them in the future.

References
Cowen, Ron. “Repaired Hubble Finds Giant Black Hole”
Science News, 145 (June 4, 1994) p. 356
Croswell, Ken. “The Best Black Hole in the Galaxy”
Astronomy, (March, 1992) pp. 30-37
Dye, Lee. “Evidence of Massive Black Hole Discovered by Astronomers” Los Angeles Times, (January
12, 1995)
p. A3+
Flamsteed, Sam. “99.9 Percent Sure”
Discover, 16 (January, 1995) p. 32
Kaiser, Jocelyn. “Does the Milky Way Hide its Black Hole?”
Science News, 147 (April 15, 1995) p. 230
Majeski, Tom. “Evidence of Second Black Hole Detailed”
Knight-Ridder/Tribune News Service, (May 31, 1994)
p. 0531K6533
Naeye, Robert. “Faster Than Light?”
Discover, 16 (January, 1995) p. 33
Sawyer, Kathy. Monstrous, Dark Stranger Seen in Neighborhood of Galaxy” Washington Post,
(April 10, 1991) p. A2
Sawyer, Kathy. “Scientists Detect 12 Black Holes”
Las Vegas Review-Journal+ Sun, (August 2, 1992) p. 21E
Shipman, Harry L. Black Holes, Quasars, and the Universe
Boston, Houghton Mifflin Company, 1980
Taylor, Ronald A. “Astronomers Spot Massive Mystery”
Washington Times, (April 10, 1991) p. A4

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