Formation and Sustenance of Black Holes
Introduction
Formation of a black hole occurs at the death of a sufficiently large enough star, and consists of
all of the star matter condensing into a single point, called the singularity. Once this happens there is no
way to get the matter back out of the black hole. Black hole formation can be a tricky subject to wrap
one’s head around as it involves exorbitant speeds and bone crushing gravity. Many people don’t think
about black holes because they are so distant, but some, like cosmologists and astronomers study deep
space and are intrigued by such a phenomenon. This paper will describe the basics of black hole
formation, and is intended for younger scholars who may be leaning toward astronomy and are
interested in these mysterious behemoths.
Black holes are arguably the most exotic and awe inspiring objects in the Universe. It is no
wonder that not many people are informed on them because of them having little to no effect on our
lives. With the use of space telescopes, microwave readers, and many other technical observing
devices, a black holes genesis, life, and exodus can be further understood and we can gain
understanding.
Genesis
So what makes a black hole come into existence? The answer is when any matter reaches a
critical density or mass over volume. This is most readily seen at the death of a star. The nuclear fusion
that acts as the fuel source for the star, also keeps it “puffed up.” That is to say that the weight of the
star material is balanced with the outward force created by the fusion in the center throughout the
star’s life. When the star runs out of fuel, it no longer has the same outward force and it begins to
collapse into the center with unfathomable force and speed. If the star is big enough, meaning the mass
of the star can be gravitationally compacted into a small enough volume, a black hole is birthed and the
center of the former star becomes the singularity. The singularity can be thought of as the infinitesimal
point in the center of the collapsing star, into which all the mass falls. Saying that mass falls to a point
can be confusing because that mass occupies volume and the singularity has no volume. All of the mass
falls in and the gravitational effect of the mass is still felt, but it’s not “there.” This brings us to a
question at the forefront of black hole research. What happens to mass that falls into a black hole and
seemingly disappears at the singularity? The answer to this question will put the author into contention
for a Pulitzer Prize.
Schwarzschild radius
In order to further understand the workings of a black hole, an important concept should be
defined. This concept is called the Schwarzschild radius. Without getting unnecessarily tedious, a
Schwarzschild radius is a radius of a sphere beyond which the escape velocity is greater than the speed
of light and before which it is not, if you are travelling toward the center. To imagine what escape
velocity means think about shooting a gun in the air. If you shoot straight up, the bullet will go up with a
certain velocity and then come back down. One could imagine if we keep increasing the initial velocity
by getting a bigger gun, then the bullet will go higher and higher. At a certain point, the bullet’s initial
velocity will be enough to see it clear from earth’s gravitational field and it won’t come back down. It
will just float into space. This is earth’s escape velocity. If a black hole’s escape velocity at the
Schwarzschild radius is the speed of light that means that even light cannot shine back from a black hole
once its source is beyond the Schwarzschild radius. The hole is literally black at this part.
Accretion Disks
A commonly asked question when analyzing a black hole is “If a black hole is black, then how
can we see it?” The answer is that a black hole actually gives off a lot of light and is not completely
black. A good way to describe this is to define
the meaning of an accretion disk. This can be
compared to our solar system because of the
way that the eight planet’s plane of orbit are
relatively coplanar. That is to say that the all
obit the sun in the same “disk” called an
accretion disk. You could imagine that when
a star, or any other matter in the universe for
that matter, comes too close to a black hole,
it begins to orbit. As this matter is orbiting it
gets faster as it gets closer to the black hole.
The matter is moving so fast and a small
change in distance from the singularity means
such a large change in the orbiting speed that
the atoms rub together causing friction,
A black hole devouring a star and bringing its matter into a swirling
accretion
disk. The vertical jets in blue are another way that a black
causing heat to be produced, causing light to
hole expels energy, but this is not covered in the scope of this paper.
be cast. Before the matter falls past the
Schwarzschild radius and is still in the accretion disk, any light it produces can escape. For this reason,
black holes are actually pretty bright.
Gravitational Lensing
Other than seeing a black hole’s accretion disk, there are a few other ways that let us know that a black
hole exists in this spot at which we are hypothetically looking. These other detection parameters are
good insight into how a black hole works. One is gravitational
lensing. In order to understand this detection method, one
must first grasp that a black hole can refract or bend light. As
we know, light has no mass, so how does it bend when
influenced by a massive object? The complicated truth is
that’s pace and time are interwoven into a fabric that we call
space-time. It is this space-time that bends and not the
actual light. This gets into Einstein’s general theory of
relativity which is not within the scope of this paper. For our
purposes, we will imagine that light does have mass and that
it can be influenced by sufficiently massive objects. This
A black hole’s gravitational lensing effect.
assumption strays from reality, but we will end with the same
result. This shortcut is used for simplicity’s sake only. Imagine a star behind a black hole, then a
telescope looking at it while they are all in a line. The light is given off in all directions. As we are
assuming, light can be bent by a massive enough object like a black hole. This means that the light that
originates from the star, comes close but doesn’t hit the black hole, and is bent or refracted back into
the telescope. If you are imagining a circle of light around a black hole, you are imagining gravitational
lensing.
Conclusion
From the point of a star’s collapse, gravity is the impetus for black hole. Once the star collapses
enough, gravity goes off the deep end and the singularity starts to swallow everything around it. Matter
that swirls around the black hole heats up and creates light, to signify the existence of a black hole. The
singularity is so massive that it can bend light, causing gravitational lensing to denote the relative
location. A black hole lives off of matter, and is commanded by gravity.
Black holes remain one of the most, if not the most bamboozling enigmas known to man. Great
leaps have been made in the quest to understand black holes in the recent decades but only a fraction
of the oddities associated with black holes are understood, while fewer can be comprehended. This
paper delves into the surface of the study of black holes, while leaving copious amounts of observations
absent. The quantum conundrums contained within the Schwarzschild radius were enough to confound
the minds of geniuses Like Einstein and Kepler. This leaves no doubt that black hole research has
extremely far to go, and we will be discovering more and more as we advance as a species.
Bibliography
http://static.ddmcdn.com/gif/blogs/6a00d8341bf67c53ef01630128de99970d-800wi.jpg
https://en.wikipedia.org/wiki/Accretion_disc