[Image source: nasa.gov]
The universe is the place where we live in. It is the place where everything lives inside. The observable universe is about 91 billion light years in diameter. Nobody knows about the size of the whole universe. In the old ages people thought that the Earth was in the middle of the universe. Now people know that the Earth is not in the middle of the universe. The universe may have started out with a theory called the Big Bang Theory. This is a widely accepted theory that the universe started from a huge explosion.
The universe may have started by the big bang. It started expanding really fast in a process called inflation. Inflation is where the universe started to expand really fast. After that, it was the dark ages. At that time no stars had formed yet. A few hundred million years later, the first stars started to form. This began to form galaxies and planets and other objects. This was the power of dark matter. Dark matter is just like gravity, it wants to squeeze everything. Later, dark energy started to expand the universe. Dark energy is the opposite of dark matter, it wants to expand it. Right now dark energy is expanding the whole universe. In the whole universe there is about 68% dark energy, 27% dark matter, and 5% matter.
[Image source: nasa.gov]
There are many theories about what will happen to the universe when it dies. Let's just talk about a few theories. One theory is called the Big Crunch theory. If there is not enough dark energy then gravity will stop expanding and make it shrink. It will crush the universe into a huge supermassive black hole which has the mass and size of the whole universe.
Another theory is the Big Freeze theory. In the Big Freeze the universe will keep on expanding until the stars formation will be very low since the universe will be very cold. It will keep on expanding forever.
Another theory is the Big Rip. In the Big Rip, dark energy moves faster than the speed of light which is about 300,000,000 m/s. It will make the universe rip apart since it is going faster than the speed of light. First planets and stars begin to rip apart and then galaxies and then atoms begin to break apart.
One other theory is the Big Bounce theory. In the big bounce theory the universe keeps on contracting and expanding and it will be doing this forever. The most likely one is the Big Freeze.
People do not really know the whole universe's shape. Many people think that the universe is sphere or flat or something that looks like a cylinder. There might be no shape because the universe might be infinite.
[Image source: nasa.gov]
The size of the observable universe is about 91 billion light years or more. The size keeps on increasing since the universe is expanding. There are lots of regions in the universe. One is a supercluster. We live in the Virgo Supercluster which is located in the Laniakea Supercluster. There is something called a void. A void is a place where it is empty. The largest void is the Bootes Supervoid. It is called a supervoid since it is so large.
[Image source: nasa.gov]
(Super Void) [Image source: nasa.gov]
The universe is about 13.8 billion years old. The oldest galaxy GN-Z11 is about 13.4 billion years old! This galaxy used to be 13.4 billion light years away, but it is right now about 32 billion light years away from us. It is so far away because the universe is expanding. It is expanding because of dark energy.
Spacetime is four dimensional plane where anything that has mass and gravity can bend it. It can bend space - time. Black holes create holes in spacetime. Black holes can make a gravitational lensing effect because it distorts spacetime.
[Image source: nasa.gov]
The universe is very interesting. Everyday scientists are trying to solve mysteries about the universe. The universe is only for limited time. We should like our universe until it ends. It gave birth to us so it is our responsibility to respect our universe. The Earth is also part of the universe so we should take care of it. We should be happy that we are in this universe. There might be a multiverse that we reside in. We should take care and love our universe forever. Nobody knows about the beginning and end of the universe. Scientists gave their different type of theories about how the universe was created and how the universe can end.