or
Let there be matter!
From
10-32 to 10-12
seconds... the birth of quarks
At the end of the inflationary period, around 10-32 seconds after the big bang, the Universe was the size of an orange and had a temperature of 1025 °K.
It
was at this moment that the first particles of quarks and antiquarks
surged from the quantic void into a bath of photons. This materialisation
of matter and of antimatter
would soon start a fight to the death between these two antagonistic componants:
The pairs of particles-antiparticles would annihilate each other
to become light (photons). Then, these same photons would, by a symmetrical
reaction, materialise (Don't forget E=mc² !) into particle-antiparticlepairs.
The Universe is then a soup of quarks and antiquarks in perpetual annihilation
- matterialisation !
It's necessary to point out a capital fact: the initial creation
of particles-antiparticle pairs would not have happened in a perfectly
symmetrical manner: A little excess of matter would appear:
For 1 000 000 000 antiquarks created, there would be 1 000 000 001
quarks created, and thus 1 single quark would survive the future grand
annihilation : A ratio of 1 for 1 milliard !
And this is how a break in symmetry is responsible for the existence
of the matter of which we are actually constituted!
From
10-12 to 10-6
seconds... the birth of leptons
Temperature = 1015
°K.
The Universe continually cooled and swelled to become a sphere of 300
million kilometres.
The weak electric interaction in turn split apart into the weak and electromagnetic interactions. The 4 fundamental interactions of the Universe are thus differenciated as they are still found today.
Moreover, the soup of quarks and antiquarks became enriched with light
particles, sensitive to the weak interaction: the leptons. These leptons
regrouping electrons, muons, tau and their corresponding neutrinos, as
well as their antiparticles.
From
10-6 to 10-4
seconds... the phase of the hadrons
Temperature = 1013
°K.
The volume of the Universe is equivalent to the
current solar system, that is to say 1013
m.
The lowering of temperature meant that the quarks no longer had enough energy to exist alone: The strong interaction could therefore group quarks into hadrons:
In effect, we have seen that there was a slight
excess of quarks (1 quark extra for 1 milliard antiquarks) in the primitive
soup at 10-32 s.
Thus almost all of the newly formed protons and neutrons, finished by annihilating
themselves with their antiparticles: Finally there only remained a slight
excess of matter. The temperature became too low for the photons to be
able to rematerialise into paticle-antiparticle pairs. The rare surviving
protons and neutrons thus "set" and formed the matter of the Universe.
From
0,0001 to 1 second... the phase of the leptons
Temperature = 1010 °K or 10 milliard degrees.
At this temperature, there was a second grand
annihilation of matter and antimmatter: this time it concerned leptons
and their antiparticles.
In effect, photons, exhausted by the expansion
of the Universe, no longer have enough energy to convert (by materialisation)
into electron-antielectron pairs.
Lepton-antilepton pairs where then subjected
to the same sort of thing as hadrons: they were annihilated in an ocean
of photons and only a fraction of a milliardth of leptons survived the
slaughter. Exit the antimatter of the Universe!
Matter is from now on for the most part complete, but the temperature is still too elevated for atoms to be able to form. The Universe is a big luminouse mass of burning plasma formed of the celebrated hadrons and leptons.
Neutrinos ceased interacting with matter
and separated.
From
1 to 3 seconds... formation
of the first atomic nuclei
The temperature drops to 106 °K or 1 000 000 °K : this is sufficiently low for protons and neutrons to be able to durably assemble.
Protons
alone form hydrogen nuclei.
The protons and neutrons which meet, could also
assemble to form helium nuclei (2 protons + 2 neutrons):
This phase is called the primordial nucleosyntheses.
The matter of the Universe composed itself of nuclei of the following atoms:
99% of the matter currently in the Universe formed at this distant epoque.
The remaining 1%, having still not appeared, is constituted of all of the
atoms having more than 2 protons in their nucleus, amongst which are atoms
of Carbon, Nitrogen and oxygen of which we are constituted. All of these
complex atoms would be formed in the thermonuclear reactions at the heart
of the future stars, still to be born...
At this epoque, electrons are still free
because they are very energetic. They still don't therefore link up to
the nuclei to form H (Hydrogen) and He (Helium) atoms.
From
3 minuts to 300 000 years... The Universe becomes transparent
Temperature = 10.000 °K
Until this point, photons were continually emitted and absorbed by the surrounding particles. Then, with the fall in temperature and density of the Universe, photons ceased to interact with matter: they could finally traverse the Universe without obstacle: there was a decoupling between photons and matter: the Universe suddenly became transparent. This liberated light coming from all points in space can actually be captured by our astrophysicists: this is what is called the famous "fossil radiation" at 3°K of the Universe, relic of the big bang.
Fossil radiation at 3°K seen by the COBE satellite
300
000 years and after... the formation of the first atoms
300 000 years after the big bang, the electrons could finally be captured around the Hydrogen and Helium nuclei present. The first atoms born at last.... and the electromagnetic interaction could finally plainly play its role.
These ultra-rapid events of the birth of the Universe
unravelled around 15 milliard years ago. Certain recent astrophysical
discoveries lean towards an even younger age of the Universe, of the order
of 10 milliard years.
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All of the other atoms from the periodic table would not have been created if it wasn't for the life and death of the stars still to come. Don't forget that we ourselves (large masses of thinking atoms) were born of "star dust", as said so poetically by our french astronomer star, Hubert Reeves. |
Still it is that the evolution of the Universe is marked by the following events:
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crazyflash:
Universal Production presents "The big boom" |
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