By: Veera Mehta
What are black holes?
A black hole is a very hot region in space, where the pull of gravity is so incredibly strong that even light can not escape it. This is a point that is infinitely dense and miniscule that no laws of science and time are applied here.
How are black holes formed?
Black holes are what are produced towards the end of the life cycle of a star whose mass is larger than the sun.
- Nebula: Stars are initially formed by huge clouds of dust and gas which are pulled together by the force of gravity. These nebulae are mainly composed of hydrogen particles. As the nebula gains mass, it spins faster and faster until the nebula flattens into a disc. This increases the thermal energy of the star.
- Protostar: At the beginning of the protostar stage, the increasing temperature causes the hydrogen atoms to fuse together to form helium atoms. This occurs because the increasing hydrogen and helium atoms convert the gravitational potential energy into kinetic energy, causing the protostar to fall inwards. The protostar becomes denser and hotter until the outer layer of the star collapses. Soon, the temperature becomes hot enough to initiate nuclear fusion reactions, entering the star into a long main sequence phase.
- Main Sequence Star: This is the stage our Sun is currently in. During this phase, multiple fusion reactions start to occur more rapidly. At this stage, the star is in a form of equilibrium (preventing the star from actually collapsing). This state of stability is due to the thermal expansion from the nuclear fusions being balanced out by the inward force of gravity.
[NOTE: After this phase we will only be focusing on the path for stars which have a mass greater than the Sun.]
- Red SuperGiant: When the hydrogen atoms run out, the core is not hot enough to withstand gravity and collapses. A large star will turn into a red supergiant. Here, heavier and heavier elements fuse together until an iron core is made.
- Supernova: Elements heavier than iron can not fuse together. Hence why, the force of gravity is overwhelmingly greater causing the core of the star to collapse. This causes a huge explosion called a supernova.
- After the explosion, the star can form into 2 things.
- A tiny, very dense neutron star.
- The core of really massive stars will collapse right down to a point, forming a black hole.
The Singularity:
The outer layer of black holes is called the event horizon. We as humans can not see what is beyond this horizon. Anything in space that passes this point is considered to never leave the black hole. In the centre of the black hole, there is what’s called a singularity. The singularity is an inescapable event occurring in the future. Every time something falls into a singularity, its mass increases, simultaneously increasing its event horizon and ergosphere (region outside the black holes, where objects are begun to get sucked into the event horizon). Although it is unknown what happens inside a black hole, many scientists theorise that this black hole could act as a gateway to another universe, since there are many similarities between the singularity of a black hole and the origin of a Universe.
The Collision of 2 Black Holes:
When 2 incredibly massive, extremely dense black holes are caught up in each other's ergosphere, they start orbiting inwards towards each other at a fraction of the speed of light, producing strong gravitational emission when closer together. As the black holes orbit each other, the waves carry information about their masses, spinal orientation and orbital parameters. As the black holes collide, they don’t explode since there are no shells to collapse nor is anything released from either of their singularities. Instead, just fractions of seconds before collisions, they release energy equivalent to millions of suns, also known as gravitational waves. This makes them potential sources for detection.
These gravitational waves are detected by highly sensitive instruments called LIGO, Laser Interferometer Gravitational-Wave Observer. There are only a few of these in the world since a perfectly level and quiet place is needed for the observers to pick up these waves.
The Big Crunch:
A possible end of the Universe is theorised around the idea of black holes. It is believed that at one point in time, black holes will merge and expand to the extent where they will no longer be able to. Instead, the will start to contract and begin collapsing in on itself due to extreme amounts of gravity in its singularity. All the massive stars will start to die out and space will start to contract as everything is sucked into the singularity of the black holes. All of the universe’s information of time, matter, space and science will lie inside the singularity of a huge black hole. This will continue until just before the end of time when all the black holes will be stacked up within each other.
Add comment
Comments