Timeline of the Universe

The Big Bang

Everything started from a single, incredibly hot and dense point in space around 13.8 billion years ago. Before just one second had passed, the universe underwent a massive expansion called "inflation," which doubled its size about 90 times. For this to happen, the universe would have had to be filled with an unstable form of energy, which is currently unknown.

The Stars and planets

The first stars were born when the universe was around 100 million years old and were made entirely of hydrogen and helium, which made heavier elements in their core. As for galaxies, they formed all over for the first 1-2 billion years of the universe, all of which eventually led to the Milky Way galaxy, our solar system, Earth, and us. The solar system formed around 4.5 billion years ago from an interstellar cloud of gas and dust, due to gravity and a nearby star going supernova, from which we got the elements required for life as we know it. When the dust collapses, it forms what we call a "Solar Nebula," which is a spinning disk of material. Because of gravity, more and more material started falling into the center of the disc, which eventually led the hydrogen atoms to fuse into helium because of the immense pressure. The leftovers that didn’t end up at the center collapsed into each other, making larger and larger objects, which became planets, large moons, and dwarf planets. Smaller pieces became smaller moons, asteroids, meteoroids, and comets. The first four planets, which are Mercury, Venus, Earth, and Mars, are all rocky planets, since they could withstand the heat from the sun when the solar system was first born. The other planets, Jupiter, Saturn, Uranus, and Neptune. Jupiter and Saturn being gas giants, and Uranus and Neptune being ice giants.

The Moon and the Beginning of measurement

The moon was formed when a protoplanet collapsed into Earth about 4.5 billion years ago. Earth was incredibly hot back then, full of molten magma, and eventually it cooled down. Liquid water started flowing everywhere, creating the oceans and eventually life. All of which eventually leads into the present moment, where intelligent life has formed on Earth, built massive cities, theorized how the universe was created, wondered how everything works, and created a system of measurement called mathematics.

Humanity and the beginning of the End

We have come a long way as a civilization; there’s plenty of stuff we need to fix right now. Eventually, like everything, the Earth and the solar system will die. In approximately 5 billion years from now, the sun will run out of hydrogen to burn as fuel, and it will expand and become what we call a "red giant." At this stage, the sun will end up consuming Mercury, Venus, and possibly Earth. If it doesn’t end up consuming Earth, it will still become uninhabitable because of the massive temperatures. That doesn’t mean humans will die off though, since, first of all, this will happen in about 5 billion years. So assuming we survive the next 1000 years, we should already have colonized other places in the solar system and beyond. Also at this red giant phase, colder planets, moons, and dwarf planets like Pluto may become habitable since the sun expanded and they now receive more heat.

The Big Freeze

When the solar system dies off, there’s still a whole universe to explore. So, will the universe itself eventually die? The answer to that is sadly, yes. Cosmologists have theorized different ways that the universe might end, although this will happen in an unimaginably long amount of time. The most likely to happen is called "Heat Death" or "The Big Freeze." After some trillions of years from now, the universe will have expanded so much that we won’t be able to see distant galaxies. The Milky Way Galaxy, which at this time has already merged with other galaxies, would seem like the entire universe for a new civilization. Around 100 trillion years from now, stars will stop forming at all, and eventually galaxies will be gone as well. The only thing left would be black holes, which would slowly evaporate due to Hawking radiation. By slowly, we mean very, very slowly... After approximately 1 googol years, which is a 1 followed by 100 zeroes. There won’t be any celestial objects left, all the energy left will be evenly distributed at near absolute zero, which is the coldest temperature possible.

Seems quite scary, yes, but this will happen in an unimaginable amount of time, as said before, and we won’t be here by the time it happens. So let’s enjoy the present moment, where we have a wonderful universe filled with stars and so much to discover.