Imagine that the universe was created 13.8 billion years ago, it is impressive! Carl Sagan was an incredible popularizer on this topic, he gave us an exciting vision of the universe, deeply illustrated and easy to understand. He made us see how science has revolutionized our understanding of where we are and who we are.

“The Cosmos is all that is, all that was, or all that ever will be.”

In Sagan's book: COSMOS, he tells us that the size and age of the Universe exceed the normal understanding of man and that in a cosmic perspective most human concerns seem insignificant. The dimensions of the Cosmos are so large that it is impossible to use units such as meters or kilometers to measure them, so we measure distance with the speed of light. In one second a ray of light travels almost 300,000 kilometers, that is, it goes around the Earth ten times. Under this argument, the Sun is eight light minutes away. In one year, light travels almost ten billion kilometers through space!

A galaxy is made up of gas and dust and billions and billions of stars. Within a galaxy there are stars and planets. There are a few hundred billion galaxies each with an average of a hundred billion stars. The Milky Way contains about 400 billion stars!

Before the creation of the Universe, nothing existed, neither matter, nor time, nor space. In a book called the history of the universe, by Juan Angel Torti, he tells us that astrophysicists have come to the conclusion that the Universe emerged from the “energy of the vacuum”, where nothing was found, there was completely nothing, from there tiny “bubbles” of energy began to emerge and then disappear. But, 13.8 billion years ago, one of those “bubbles” burst and unleashed a very high temperature, that explosion would be the famous Big Bang, from there the universe originated and spread, thus creating space, time and subject. Most likely the elements that formed first were hydrogen and helium atoms.

“During its first moments, the Universe was a kind of “plasma”, very dense and hot, composed of quarks and anti-quarks (matter and antimatter) that inhibited each other, leaving a surplus of quarks. These, which are the smallest elements into which matter is divided, combined with new elementary particles to end up forming hydrogen and helium atoms, the two main elements that make up the Universe.
Three minutes after the Big Bang, the temperature dropped to about a billion degrees Kelvin and the Universe continued to cool and expand. Subsequently, the Universe “stabilized” and was, 99%, composed of two-thirds hydrogen and one-third helium.

About 380,000 years after the initial explosion, and as the temperature continued to drop, the photons – which are the particles that transport energy in the form of light – were released and shot in all directions. The Universe, which until then was opaque, became luminous.”

Juan Angel Torti,

This is impressive!

Speaking from a human perspective we can say that the Earth is “unique” in our universe, because it is the only planet we know where there is life (the life we know). Our planet is at the correct distance from the Sun, which makes it possible for all the organisms we know to live on it: plants, animals, bacteria, fungi, protozoans, etc. It is very profound to discern that until now there is no other known planet where the human species can subsist. As Carl says, we should be grateful for having a place, a space to live in the company of others.

It is very interesting to read Carl Sagan's reflections and see how science has changed in recent years, now in 2024 we can see that there are new inter, multi and transdisciplinary research to know and understand the origin of life and extraterrestrial life, addressing the question of whether there is life beyond Earth, and how humans can detect it if there is, and even travel to new places.

With technological advancement and the knowledge that continues to be built we can see how all this has advanced, now (in 2024) we see that projects are already being carried out to inhabit Mars, which will expand the possibilities of exploring other worlds that exist in our country. universe, knowing how it works and realizing the immense universe in which we live, and as Carl says, these answers would reveal to us that we are a “speck” in the immense space around us.

Our planet Earth is 4.55 billion years old, and we can know this thanks to radiometric dating, a methodology that measures the age of rocks using unstable isotopes. The oldest rocks are more than four billion years old. of years, that is why we know the age of the Earth.

Life originated through several series of reactions of organic compounds that gave rise to more complex biochemical structures. Planet Earth, at that time, was very hot and cold at the same time and the atmosphere was very lacking in oxygen. The compounds found at that time were water, dinitrogen, dihydrogen, carbon monoxide, hydrogen sulfide, among others.

From these compounds, small and medium-sized molecules began to form, such as sugars, nucleic acids and proteins. Giving rise to protocells (lipid membranes). The first cells emerged 3.9 billion years ago and, therefore, the first single-celled organisms. And it is here where the protagonist is LUCA (Last Universal Common Ancestor) our ancestor and the ancestor of all living beings, so to speak, LUCA is our great-great-great-great-great...-great-grandfather.

LUCA was an extremist, he lived in extreme environments, such as the hydrothermal vents at the bottom of the oceans, which are cracks from which hot water flows from the interior of the Earth. Who wouldn't want to be LUCA? As time went by, as the environment of planet Earth changed, these organisms also began to change, adopting new mechanisms of survival and adaptation, emerging photosynthetic cells, eukaryotic organisms (this is what the Endosymbiotic Theory of Lynn Margulis talks about) and the multicellularity. When multicellularity originates, what follows is history, an immense series of organisms began to emerge and evolve.

Thanks for reading me.