The Universe

We now have the answers to the stuff the Universe is made of and how it evolved. The Planck satellite has measured precisely the first photography of the Universe when it was only 400 thousand years old. The following picture is a projection of the whole celestial sphere on a flat screen (like a whole Earth map)

After numerous calculations, the scientists have deduced the age of the Universe, 13.8 billion years ( give or take tens of million years). Three phases are important to grasp in the expansion of the Universe:

1. the inflation which started just after the Big Bang (within the first trillionth of a trillionth of a second), an exponential growth of the distance between any two points, which ends with the creation of matter (nothing to do with the monetary increase)
2. the power-law growth of the Universe during the first 5 billion years. This phase has seen the appearance of structures in the Universe leading to galaxies, stars and planets
3. the second inflation (also called dark energy): for the last 8 billion years, we have had another exponential growth of the distance between galaxies with time such that the dilution will make us drift apart from other galaxies forever.

The visible matter of the Universe is only ten percent of the total atomic matter. This atomic matter is only a fifth of the total matter, the rest being the dark matter which nature is totally unknown and has not been detected on Earth yet.