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Published on Apr 15, 2013
TIME ZERO Was there ever a beginning to the Universe? Thursday February the 28th, 2013 5.45 pm
Étienne Klein Research Director at CEA, Commissariat à l'énergie atomique et aux énergies alternatives (Atomic Energy and Alternative Energies Commission) In cooperation with Italy's French Embass
For over a century we have been aware of an expanding universe: galaxies grow apart at very high speed a little like the shards after an explosion. Since 1998 we have also been aware of the acceleration of the expansion. Let us imagine showing a movie backwards, that is going back in time: if we could do it, we would see a very small universe until about 13.7 billion years ago it converged in a point no greater than an atom. It is what physicists call its initial singularity, at least this is what the Big Bang theory suggests. However is this initial singularity realistic? Can we hypothesize a point like object with infinite density and temperature? Logically there is something unconvincing in this cosmological model when we push it to the point of Time Zero. This is why research is increasingly active focussing on the very first moments of our Universe. The solution of the problem could be paradoxical and could be summarized in the questions: are we sure that the Universe ever had an Time Zero?