A new Newton for the Nobel in Physics for 2009

The recent Nobel Prize in physics, awarded to Americans John c. Mather and George f. Smoot for their discovery of the cosmic background radiation (RCF), confirms all that Astrophysics is well become a "Big Science": a discipline claimant of the extremely heavy to experiment with and make progress in the research means. Our two researchers share in this prestigious award with... a satellite!

It is listening to Cobe (Cosmic Background Explorer), a space observation satellites from Nasa that they detected a fingerprint left in the universe, 380.000 years after the Big Bang. Divine surprise: this print contains trace trace, kinds of "lumps", showing the ability to aggregate material to achieve much, much later, the universe we know.

It is difficult without these tiny variations to apprehend the path between the Big Bang and the State of the universe today: the passage of an empty homogeneous and heterogeneous universe expanding that surrounds us. "Are these lumps which will later give birth to galaxies", explains Pierre - Olivier pruning, head of the Department of Astrophysics of the Commissioner for Atomic Energy (CEA) and who knows well the new Nobel. Revealing footprint is so small that researchers were first taken him for a parasitic noise.

There is much to understand the immense period between trace listened by Cobe and massive galaxies of today. To do this, we need to solve one of the great enigmas of Astrophysics: that of dark matter. 96 Of the nature of our universe remain unknown, of which 23 is dark matter. The rest is just as mysterious: is the dark energy. Titles of works of science fiction that cover a reality accepted by the scientific community and a proliferation of more or less daring assumptions.

The role of the missing mass

The first signs giving rise to the concept of dark matter date back to 1933, when Swiss astronomer Fritz Zwicky found that the dynamic mass of a cluster of seven galaxies, calculated using the laws of Newton, is superior to his "light weight". Clear: that it weighs does not correspond to what he sees. a little, as if a heavy but invisible mass explained the difference. This is the first appearance of the "missing mass" or "dark matter".

Many then, from the 1970s, confirmed the necessary existence of dark matter. In 2003, the American magazine "Science" recognized as the "major of the year scientific event. Search multiply: in 2006, results are published on the Bullet, formed two clusters neighbouring cluster returned to hit 150 million years ago. They confirm a distribution of normal matter and dark matter.

Since dark matter exists and represents 23 of the universe, it is logical to wonder about its composition. The assumptions remain numerous. Most come from fundamental physics and postulated the existence of yet unknown particles: Wimps (Weakly Interactive Massive Particles) or heavy particles interacting weakly with matter. "The connection is made between the infinitely large and the infinitely small." "Theories predict this nature of particles and it is precisely that which is needed to explain the dark matter," explains Grégoire Moreau, lecturer at the University of Orsay near Paris.

This is the case of the super-symétrique theory, which provides that each known particle would be his partner. Or those who imagine that space has additional dimensions, in which particles would travel. "A particle wanders in a 5th dimension and that we would not move would appear us as very massive." "And the effective mass could play the role of the missing mass," continues Grégoire Moreau.

Newton challenged

For other physicists, do not search for particles but review the current laws of physics, and for example put in issue the law of gravitation of Newton is not valid for the very large distances. It is the theory MOND (Modified Newtonian Dynamics), advanced by the Israeli Mordechai Milgrom astronomer in 1983. A theory controversial for its deficiencies, such as the difficulty to explain the movements of galaxy clusters. A very speculative idea as recalled by Pierre-Olivier pruning, "the assumption is that the physical laws are valid everywhere." And for the moment the standard model is resistant.

The evidence will come, as usual in science, experimentation. Instruments, more and more sophisticated, will be used to differentiate between theories and whether the framework of current physics is valid or whether to base a new. Many projects of telescopes are in competition in Europe and the United States. The great European hope to three American projects that still has a name of science fiction: Dune, Dark Universe Explorer.

He was born in 2015, this project will be a new space telescope wide field. He will have to prepare maps of the sky including dark matter and measuring the behaviour energy dark. Imaging of Dune will combine in a new manner the ability to escape from the disruptive effects of atmosphere and very high sensitivity, two qualities that are not compatible today.

Particle physicists expect them to live a moment of history in 2008, when the first results will emerge from experiences allowed by the Large Hadron Collider (LHC) under construction. This new Accelerator at CERN in Geneva will take over of the current instrument to achieve new levels of energy in the world of particle physics. The entire scientific community awaits him on the Higgs boson but it will also seriously test the WIMP hypothesis. Grégoire Moreau dream already: "I expect a historic date, which will arise a new physics." A new Newton for the Nobel in Physics for 2009