(Picture source: Science Photo Library/Getty)
At the beginning, there was nothing. . .
Then, about 13.7 billion years ago, the universe formed.
We still don't know the exact conditions for this to happen, and whether there was time before. However, using telescope observations and particle physics models, researchers have been able to piece together a rough timetable for major events in the universe. Here we look at some of the most important historical moments in our universe, from its infancy to its ultimate death.
Big Bang
It all started with the Big Bang, and Big Bang "is a time, not a point in space," theoretical physicist at Caltech Sean Carroll told Live Science.
Specifically, this is the moment when time itself begins, and the moment when all subsequent moments are calculated. Despite its well-known nickname, the Big Bang was not a real explosion, but a time when the universe was very hot and dense, and space began to expand in all directions at the same time. While the Big Bang model points out that the universe is an infinitely small infinite density point, it’s just a simple statement and we don’t know much about what happened at that time. Mathematical infinity has no meaning in physical equations, so the Big Bang is actually the point where our current understanding of the universe collapses.
The era of universe inflation
(Image source: ESA/Planck cooperation)
The next trick of the universe is to get very big and very fast. The first 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 Back in 2014, a team believed they had discovered this expansion signal from the light of the early universe. But the result later proved to be something more mundane: interfering with interstellar dust.
quark - gluon plasma
A few milliseconds after the start of time, the early universe was really hot. We are talking about high temperatures between 7 trillion and 10 trillion degrees Fahrenheit (4 trillion and 6 trillion degrees Celsius). At such temperatures, elementary particles called quarks are usually tightly bound inside protons and neutrons , wandering around freely. Gluons carry a basic force called powerful force, mixed with these quarks in the soup-like primitive fluid that permeates the universe.
researchers have managed to create similar conditions in particle accelerators on Earth. However, this difficult-to-achieve state lasts only a few fractions of a second, both in the Earth's atomic crusher and in the early universe.
Early universe
(Image source: Getty)
At this stage, the particles have a lot of action, starting about one thousandth of a second after the Big Bang. As the universe expands, it cools down, and soon the conditions are good enough, and the quarks gather into protons and neutrons. A second after the Big Bang, the density of the universe dropped enough to make neutrino , the lightest and least interacting elementary particles, able to fly forward without hitting anything, resulting in the so-called cosmic neutrino background that scientists have not detected yet.
The first atom
(Image source: Getty)
In the first 3 minutes of life in the universe, protons and neutrons fuse together to form a hydrogen isotope called deuterium, as well as helium and a small amount of one of the lightest element lithium. But once the temperature drops, the process stops.
Finally, 380,000 years after the Big Bang, the universe was cool enough at this time that hydrogen and helium could combine with free electron to produce the first neutral atom. The photon that used to enter electrons can now move without interference, resulting in a cosmic microwave background (CMB), a relic of this era and was first discovered in 1965.
Dark Ages of the Universe
For a long time, nothing in the universe emitted light. This period lasted for about 100 million years and was known as the Dark Age of the Universe. This era is still very difficult to study, because astronomers’ knowledge of the universe comes almost entirely from starlight. Without any star body that can glow, it's hard to know what's going on.
First star
(Picture source: Gemini Observatory/AURA/NSF/Matia Ribrato, Institute of Space Telescope Science)
About 180 million years after the Big Bang, hydrogen and helium began to collapse into large spheres, producing hellish temperatures in its core, which successfully lit up the first batch of stars.
The universe has entered a period called dawn or reionization, because thermal photons radiated by early stars and galaxies decompose neutral hydrogen atoms in interstellar space into protons and electrons, a process called ionization . It is hard to say how long the ionization lasts. Because it happened too early, its signal was masked by later gas and dust, so the best scientists can say it ended about 500 million years after the Big Bang.
Large Scale Structure
(Image source: NASA)
This is where the universe starts to run, or at least the familiar run we know today. Small early galaxies began to merge into larger galaxies, and about 1 billion years after the Big Bang, the supermassive black hole formed at its center. The bright quasar produces a strong light beacon that can be seen from 12 billion light years away.
Mid-age
(Image source: ESA/Health Insurance Association and Friendly Financial Institutions Consortium)
In the next few billion years, the universe continues to evolve. Higher density locations from the primitive universe attract matter to itself under the action of gravity. They slowly grow into galaxy clusters and long chains of gas and dust, creating a beautiful silken universe network that can also be seen today.
The birth of the solar system
(Image source: NASA/Jet Propulsion Laboratory)
About 4.5 billion years ago, in a specific galaxy, a ball of gas collapsed into yellow stars, surrounded by a ring system. These rings merge into eight planets, adding various comets, , asteroids, dwarf planets, and satellites, to form a familiar star system . The third planet from the center star retains a lot of water after this process, and it may be that the comet later provided a lot of ice and water.
Earth and humans
(Image source: Getty)
In the third water world, between 3.8 billion and 3.5 billion years ago (depending on who you ask), the tiny, simple microorganism appeared in the blink of an eye. These life forms emerge and evolve into wonderful sea monsters and giant leaf-eating dinosaurs. Finally, about 200,000 years ago, there were creatures walking upright that were able to marvel at our mysterious universe and discover how the entire universe was formed.
ends? Or not?
(Image source: shutter)
Of course, this is not the end of the matter.
Physicists are still not very clear about what will happen to the universe. This depends on the details of dark energy , which is a mysterious force whose properties have not been well measured.In a possible future, the universe will continue to expand forever, long enough that all stars in all galaxies will run out of fuel, and even black holes will evaporate into nothingness, leaving a dead universe full of inert energy. Or, gravity eventually overcomes the expansion of dark energy, pulling all matter back together to form a reverse big bang called a large contraction. Or, dark energy can accelerate everything from everything else farther and farther away, forming the so-called big tear, in which the universe will really tear itself apart.
