The beginning of the world, according to research, is said to have been started by a “Big Bang”, and inhabited by fewer organisms than compared to today.

“The Big Bang perfectly explains the abundance of helium and other nuclei like deuterium (an isotope of hydrogen) in the universe,” said Yuki Takahashi, a physicist from Japan.

People refer to this period as “biblical times”, yet no one is exactly sure why existence exists, and they have not been able to explain it scientifically. For religious groups, it is believed that God created the universe in six days, referring to the Bible which states, “In the beginning, God created the heavens and the earth.”

Some people believe that the meaning of life for humans is to experience as much as they can before they die. Others that do not believe in god(s) (like Mbombo of African mythology, or Kamuy in Ainu mythology), have probably accepted the theory that we all just appeared one day and somehow grew into what we are now (some of these people also believe in Charles Darwin’s theory of evolution). Another theory, that the universe has always been here, is another popular explanation among scientists.

When someone mentions how the universe will end, they are bound to hear several different theories. For example, in 2012, it was a popular and worldwide belief that Earth would end in chaotic, apocalyptic events.

“It’s the time when the largest grand cycle in the Mayan calendar—1,872,000 days or 5,125.37 years—overturns and a new cycle begins,” said Anthony Aveni, a Maya expert and archaeoastronomer.

 One theory of the end of the universe is the “Big Crunch”, which is the exact opposite of the Big Bang. This theory shows that all the matter in the universe will eventually become too dense to hold itself together, eventually retracting to the middle altogether.

“This is, however, unlikely to happen based on current knowledge,” said Kier Harris, a physical cosmologist. “Since we’ve recently discovered that the universe appears to be expanding at an accelerating rate.”

 A similar, but more likely theory, is the “Vacuum Event”, which states that every single particle in the universe (stars, suns, planets—everything) will be pulled into a black hole. The universe will go completely dark, and that will be it (that is until the next possible Big Bang).

“Either all of space-time exists on this razor’s edge between a stable and unstable universe, or the calculation is wrong,” said physicist Joseph Lykken, a theoretical physicist from Minnesota.

Whatever the explanation for our beginning and ending is, it will most likely still be a mystery long after we’re gone.

“Everything past is unreal, everything future is unreal, everything imagined, absent, mental . . . is unreal… Ultimately real is only the present moment of physical efficiency,” claimed Fyodor Scherbatskoy, one of the world’s leading academics of Buddhist philosophy.