Have you ever wondered what is the most mysterious of all of the universe’s many mysteries?
Well, if you were to ask astronomers and physicists, their answer would most definitely be
black holes. Black holes are amazing for these three simple reasons: they distort the space and
time; they are impossible to see and the way they come about is also a tale on its own.
NB: I made this and I am very proud of it.
One of the many amazing things of black holes is their ability to distort time and space.
According to Einstein’s Theory of Relativity, everything has gravity (which is a force of
attraction) proportional to its mass, and this gravity distorts the space around it as well as the
speed at which time flows. Black holes, being an area of extremely dense gravity would
obviously have a drastic effect on the space and time around it. Depending on the mass of the
black hole, a couple hours might be decades to someone on Earth. Another interesting
example of this phenomenon is that if a person were to stand on very high mountain and
another were to stand in a deep ravine or valley, time would flow ever so slightly faster for the
person in the ravine because the effects of gravity would be more apparent the closer you go to
the source.
A black hole is a place in space where gravity pulls so much that even light can’t escape. We as
humans are only able to ‘see’ because we perceive light with our eyes, this is a problem when it
comes to black holes as we can’t see them because they suck in all the light around them. The
only way we know that they’re there is by observing the effects that they have on their
surroundings; this can be the manner in which surrounding planets orbit them (this can also
be used to determine the mass of the black hole), the ring of light surrounding the black hole
(like in the photo above). Thanks to Einstein’s equations, we know that there’s a limit on how
big ordinary stars can get. If we find an object that’s bigger than this limit, typically a few times
the mass of our sun, and the object doesn’t emit any light, we can be reasonably confident it’s a
black hole. We are also able to observe black holes in a different way, by looking for
gravitational waves, ripples in the fabric of spacetime caused by colliding black holes. We can
measure these gravitational waves to find out exactly how big these objects are, and using the
same methods as before, be reasonably confident they’re black holes. Fun fact: If our Sun were
by some miracle (reason why below) turn into a black hole we wouldn’t get sucked in, because
the mass of the object stays the same the gravity also stays the same… we’d still be dead though.
NB: A star in its final moments collapsing into a supernova distributing elements throughout
the universe. These elements travel on to form new stars, planets
and everything else in the universe.
Now, we move on the final body paragraph and honestly the one I wanted to rant about the
most, so prepare for a very long read about the formation of stellar black holes. I say ‘stellar’
black holes because there are 4 types of black holes. Supermassive black holes, most have a
mass of more than 1 million solar masses and are usually found in the center of most galaxies,
including our Milky Way. Intermediate black holes, these are usually formed when stars or
black holes collide, they are between stellar and supermassive black holes when it comes to size.
Then we have miniature black holes, which exist only in theory…for now; these can be as small
as an atom but have the mass of a mountain the size of Mt. Everest. Finally, we have stellar
black holes the star of our show, quite literally too, these (as you might have guessed by the
name) are formed when a star dies, the hydrogen within a star’s core runs out and nuclear
fusion can no longer take place. Luckily for us, black holes can only form from stars with at
least 3 or so solar masses so our Sun won’t turn into a black hole anytime soon. Anyways back
to the topic, when a star runs out of hydrogen it swells to hundreds of times its original size,
forming a red giant. The expanding outer layers of the star cool to give it that red appearance.
In about 5 billion years, the Sun will become a red giant and grow large enough to swallow
Mercury and Venus. A red giant’s core eventually loses its grip on its outer layers, which drift
off into space. The layers form a huge shell of gases called a planetary nebula with a white
dwarf, a tiny remnant of the original star, in the middle. A white dwarf cannot produce enough
heat to survive, so it gradually cools and dies. The most massive stars end their days in a violent
cosmic explosion called a supernova. The star’s core collapses so fast that it blasts away the
planetary nebula. Gas rushes outward in all directions, forming a glowing shell. A tiny, hot star
is left in the center of the shell. A supernova can shine brighter than an entire galaxy, but after
a few weeks it fades and disappears. After a supernova, the core that is left behind collapses to
form a dense object called a neutron star. A typical neutron star is more massive than the Sun,
but so dense that it is 60,000 times smaller than the Sun. A massive star continues to collapse
beyond the neutron star stage to finally form a black hole. Fun Fact: Did you know that light is
released as electromagnetic radiation along with heat and other forms of energy by stars due
the immense energy that is produced as a result of nuclear fusion; being able to harness this
source of energy on Earth would be revolutionary and would bring us into a whole new era of
technology because all that is needed for nuclear fusion is deuterium, an isotope of hydrogen,
which there is plenty in the form of H2O on our planet which is 71% H2O. This would be a
whole lot cleaner than the nuclear fission that is currently used and has the bad reputation of
producing radioactive waste which nuclear fusion does not produce. It is a shame though that
with our current level of technology we have to expend a lot to get only more from fusing these
atoms, even more so that man made nuclear fusion can only happen at places like the Large
Hadron Collider (a particle accelerator) which cost tens of billions to build.