Aristotle (384-322 BC) wrote that the universe is eternal. Observation, the foundation of science, has since shown how false this statement is (which lasted almost two millennia).
In 1925, Hubble discovered that the universe is huge and has a history.
Hubble had the idea to observe the motion of galaxies: he realized that they were moving away from us, all the faster because they were far away. So the universe is expanding. So in the past they were closer and in the future they will be further. Therefore, the Universe has evolved over time and therefore has a history. But be careful! The universe has no center! Hubble would have observed the same phenomenon no matter where it was observed.
The origin of life by Hubert REEVES.
In 1965 Penzias and Wilson discovered
fossil radiation. These are radiations that come from the earliest times (13.7 billion years ago) in the Universe. At that time, there was only very hot magma (billions of degrees) completely disorganized, without structure (without stars, molecules, atoms ...). Finally, science strives to reconstruct the history of the organization of matter, a zero degree of organization for living beings.
So it is based on the laws of physics and especially on the knowledge of the four fundamental forces of the Universe:
gravity (which makes apples fall);
electromagnetism (which connects electrons to the nuclei of atoms).
strong nuclear force (linking the components of protons and neutrons).
weak nuclear force (linking neutrons and protons).
the four fundamental forces.
It's as if the subject is programmed and obeys orders. A stone, for example, meets the gravity requirements that fall to the ground. The matter is informed! But where does this information come from? There is no answer.
Why is there something instead of nothing?
It is not possible to answer this question. In other words, where are the four forces?
is defined by its atomic structure: you remove an atom from a sugar molecule and it is no longer sugar. If you have a severed leg, it's you! living matter does not depend on the atoms or molecules that make it up !. Life is defined by its functions and not by its components.
An attempt to define life.
Living matter is subject to the laws of physics (the 4 forces), but also to the mandate of the laws of biology (birth, disease, reproduction, death ...). Hubert REEVES
Characteristics of life.
We do not have two types of programming: genetic (digestion - growth - aging ...) and mental (hand movement). Life is the most evolved form of matter. Unlike inert matter, it has a history and a memory. 3 billion years of previous evolution allowed the creation of a genome.
Life is extremely robust. It has survived 5 periods of mass extinction in billions of years. Therefore, 95% of living species have disappeared. It can survive in very aggressive environments (in underwater hot springs), but also in vacuum. Hence the question: How can life be so robust and seemingly so rare?
The origin of life.
The earth is 4.5 billion years old. Life appeared 3.8 billion years ago. He swam in the ocean. What happened between 4.5 and 3.8 billion years ago? Today, this remains a mystery. It seems that the conditions on earth were, at a precise moment, favorable to the appearance of life. But, on a cosmic scale, is it sufficient for conditions to be favorable for life to appear spontaneously? Or do I need an extra event? Again, there is no answer.
Is life rare in the Universe?
Looks like it is. Signs of the existence of extraterrestrial civilizations have not yet been identified. Enrico FERMI, in the 1950s, had already taken the initiative in this matter:
He said that if there were extraterrestrial civilizations, the aliens should already be here on Earth with us. Where are they then? And a Paradox.
Does advanced technology go hand in hand with the self-destruction of advanced species? We notice that mankind came close to annihilation during the Cold War. That is less than a century after the discovery of nuclear energy. We also note that the destruction of the ecosystem can have the same result in a few decades. In other words, the lifespan of an advanced species is not enough to allow it to reach a level that allows it to travel long distances.
Increasing cosmic complexity.
The history of the universe is the history of matter that is organized: from simple particles to living things, including atoms and molecules. We, as human beings, emit 100,000 times more energy per gram than the sun. Therefore, we are (along with other living beings) at the highest degree of complexity. The most organized matter is found in a living being.
However, mass living beings represent a very small part of the matter in the Universe. Therefore, there is a majority of disorganized matter in the Universe. This matter begins to organize during galaxy collisions or stellar explosions that allow the creation of heavy atoms.
Conditions for the appearance of life:existence
-Theory- fertile laws. We have realized that life can only occur if the laws of physics have a certain form.
-Life wastes energy. As with any thermodynamic system, a hot source (sun: 6000 ° K) and a cold source (earth: 300 ° K) are required.
-Atoms of light. It needs a weak bond (hydrogen, carbon, nitrogen, oxygen, etc.)
- it must be able to change energy quickly (methane, water).
-time: to establish balance.
-an oxygen atmosphere?