At the dawn of this twenty-first century, cosmology is at a crossroads: 95% of the universe eludes observations. To evoke the mysteries of dark matter and dark energy the Laboratoire Univers et Theorie-LUTH (Observatoire de Paris-CNRS) marks the World Year of Astronomy with a series of events from June 29 to July 10 at the UNESCO Palace in Paris.

Gathered at the initiative of LUTH's researchers, more than 400 experts, including two Nobel laureates and a Fields Medalist will evaluate the situation.

The symposium continues the week after with a conference dedicated to the public with the participation of artists and philosophers. An exhibition frames the all event.

Cosmology has arrived at a crossroads. According to the best data available, from large ground-based telescopes and space observatories: almost 95% of the universe irretrievably escape observational detection.

This missing part of the cosmos is constituted for 25% by a mysterious form of dark matter and 70%, by a dark energy whose nature is even more exotic and unknown! But what are exactly these new physical entities?

In an attempt to answer this complex and profound question: more than 400 experts will gather in Paris to evaluate the situation, and draw future perspectives. The basic principles of physics appear sometimes to be put into question. Modern cosmology is perhaps at the beginnings of a major renewal, similar to those once made by Galileo and Einstein.

The event consists of three parts: a scientific symposium in English during the first week, a series of conferences dedicated to the French public the following week, all accompanied by a bilingual exhibition. For a better framing and discussion of the cultural aspects of the universe invisible, the general public symposium is also open to artists and philosophers.

Scientific International Colloquium 29 June-3 July
The research colloquium develops around eight parallel themes :

+ Observational evidence of dark matter and dark energy

+ Dark matter and particle physics experiments

+ Fundamental theories of physics and cosmology (strings, quantum gravity, non- commutative geometry)

+ Inflation and dark energy

+ Inhomogeneous universe and backreaction

+ Dark energy as a new energy component (quintessence)

+ Modified theories of gravity (extra-dimensions)

+ Theory and simulations of cosmic structures and their evolution

After a quarter of century of research on dark matter and about a decade of intense studies on dark energy, George Smoot (Physics Nobel laureate 2006) and David Gross (Nobel 2004) together with Alain Connes (Fields Medal 1982), Abhay Ashtekar, Edmund Berschinger, Fran�oise Combes, Edward Kolb, Mordehai Milgrom, James Peebles, Jean-Loup Puget, Adam Riess, Leonard Susskind and Edward Wright, will present their contributions to animate the discussion around these important questions.

The colloquium will also be the occasion to present the first bulletin on the status of the European Planck satellite successfully launched the past 14th of May by the Ariane rocket.

The cosmologists of LUTH will present the results of their work on the interpretation of dark energy within the framework of the model of abnormal gravity ("AWE hypothesis"), their interpretation of dark energy in terms of cosmic inhomogeneities and the presence of a purely geometrical substrate, the "morphon" and finally the 3D animated images new numerical simulations on the formation of galaxy and clusters in the presence of dark energy.

A press meeting is organized Wednesday 1 July, at 1 pm during the meeting, for journalists. The most important news will be presented with the presence of all personalities attending the conference.

Public Colloquium 6-10 July
The public colloquium consists of about twenty presentation on the following themes:

+ The modern scientific representation of the universe.

+ Vacuum, black holes, dark matter and dark energy.

+ Spatial extra-dimensions and parallel universes.

+ Connections between mathematics, art and philosophy.

+ Psychoanalysis and Philosophy of Modern Cosmology

In addition there will be round tables on :

+ Color and perception of the Invisible

+ Invisible, Inexplicable or Unintelligible

+ Towards a new cosmological paradigm ?

+ Coherent understanding of reality, infinitely small and large

Among the scheduled French speaking participants are: Jean Audouze, Gilles Cohen-Tannoudji, Etienne Klein, Fran�ois Vannucci, Jean Zinn-Justin, Cedric Deffayet, Eric Gourgoulhon and Jean-Michel Alimi.

They will be joined in the discussion by the psychoanalyst Paul-Laurent Assoun, the visually handicapped computer scientist Nicolas Graner, the philosophers Jean-Michel Besnier, Paul Egre, Jean-Marc Levy-Leblond, Michel Paty, Jean-Jacques Szczeciniarz, the linguist Annie Mollard-Desfour and the Goncourt price laureate 1983, Frederic Tristan.

Exploring the Invisible Universe, Exhibition 29 June-10 July
The French-English bilingual exhibition is structured around four related themes which develops in harmony:

+ The modern emergence of an Invisible Universe (dark energy and dark matter). Along the traces of Galilei. Toward a new cosmological vision... 24 panels.

+ The obscure and invisible in the artist around the work of Pierre Soulages and a musical piece specifically composed by Chloe Nicholson for the event, The Invisible Universe, recorded by members of the Royal Philharmonic Orchestra of London.12 panels also showing original works by artists and photographers.

+ The visible and Invisible in Philosophy about the concept of invisible in several philosophical traditions.

+ Multimedia Area, a zone for multimedia interactions realized in the Laboratory of Cosmology. The visitor is invited to develop is own model of the universe. Which then he can test against the most recent observations. Several slide-shows and films are presented along the exhibition.