History of the Universe || Scientific FS
History of the Universe
How do we define our Universe?
Our Universe is a vast expanse of space, which contains everything that exists. It is so huge that we can say that it is almost entirely empty, with small chunks of physical matter and energy - which comprise of all that is in existence.
When and how was the Universe born?
The Universe was born approximately 14 billion years ago, in a massive explosion now called The Big Bang. The explosion took place in just a fraction of a second and released radiation, particles, and clouds of atoms, which gradually formed into stars and galaxies.
What were the different stages in the formation of the Universe?
Just after the Big Bang, all matter was squeezed into a tiny fireball, even smaller than an atom. Slowly, as the fireball expanded and began to cool, the tiny particles of energy and matter formed a thick, soup-like material. Galaxy pulled the particles together and atoms joined to make gases, such as hydrogen and helium. The gases clumped into clouds and the "soup" thinned out as the young Universe grew larger. After several hundred million years, the clouds began to form stars and galaxies.
Stages in the formation of the Universe
| Time after Big Bang | Era | Events |
|---|---|---|
| 10^-43 seconds | Planck era | Temperatures and pressures were too high for scientists to understand. |
| 10^-35 seconds | Grand Unified Theory Era | The strong nuclear force became distinguishable from the weak and electromagnetic forces. |
| 10^-6 seconds | Hadron era | Fireball stage in which protons and neutrons formed from quarks. |
| 1 second | Radiation era | First atoms of hydrogen and helium formed as the fireball cooled. |
| 30,000 years | Matter era | MAtter dominated over radiation. |
| 300,000 years | Background radiation started to cool. | |
| 1 million years | Ripples in the Universe resulted in galaxy formation. | |
| 1 billion years | Stars and galaxies brought light to the Universe and created the elements from which people and planets were made came into existence. |
How big is the universe?
No one knows if the Universe is infinitely large, or even if ours is the only universe that exists. However, scientists believe that the Universe is at least 156 billion light-years wide. They also believe that most of the matter in the entire Universe is invisible, and they call it dark matter. The observable matter is spread over a space at least 93 billion light-years across.
What is a light-year?
A light-year is a distance that light travels in a vacuum in one 1year; this distance is 5.88 trillion miles or 9.46 trillion kilometers.
What holds things in place in space?
All the planets, stars, clouds of gas, and other matter in space are held together by four invisible forces - gravity, electromagnetism, and two forms of nuclear force, strong and weak, which hold the particles of every atom together.
What are the eight planets of the Solar System?
The eight planets of the Solar System are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. There were nine planets, until 2006 when Pluto was downgraded to dwarf planet status.
Is the Universe expanding?
Yes! In the 1920s, American astronomer, Edwin Hubble made an observation that the universe is continuously expanding, with all the galaxies rushing away from each other. Astronomers do not know if this will go forever. If it stops and the Universe starts to contract, the galaxies would rush towards each other. Then, the Universe might end in a Big Crunch, the opposite of the Big Bang. This might set off another Big Bang and a brand new Universe!
What is Cosmic Microwave Background radiation?
The Cosmic Microwave Background radiation is believed to be an effect of leftover light from the big bang. These are minute temperature variations that are linked to slight density variations in the early Universe. This faint glow fills the Universe and can be observed today with an average temperature of about 2.725 Kelvin. The CMB radiation which believed to have given rise to the structures that populate the Universe today: clusters of galaxies, as well as vast, empty regions, was detected by two American radio astronomers - Arno Penzias and Robert Wilson - in the mid-1960s.
The term "Big Bang" was coined by the English astronomer and mathematician, Sir Fred Hoyle, during a 1949 radio broadcast.
The three most common elements in the Universe are hydrogen, helium, and oxygen. Scientists believe that hydrogen comprises approximately 90 to 99 percent of all matter in the Universe.
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