A team of
researchers have performed the first-ever computer model
of the structuring
of the entire observable universe, from the Big Bang to the
courtesy of CNRS (Délégation Paris Michel-Ange)
A team of researchers from the
Laboratoire Univers et Théorie (LUTH, Observatoire de Paris/CNRS/Université
Paris Diderot) (1) coordinated by Jean-Michel
Alimi has performed the first-ever computer model simulation
of the structuring of the entire observable universe, from the
Big Bang to the present day.
The simulation has made it possible
to follow the evolution of 550 billion particles. This is the
first of three runs which are part of an exceptional project
called Deus - Full Universe Run (2), carried
out using GENCI's new supercomputer CURIE at the CEA's Très
Grand Centre de Calcul (TGCC).
This simulation, along with the two
additional runs expected by late May 2012, will provide outstanding
support for future projects dedicated to the observation and mapping
of the universe. These simulations will shed light on the nature of
dark energy and its effects on cosmic structure formation, and hence
on the distribution of dark matter and galaxies in the universe.
After several years' research, six
scientists (3) of the cosmology group at LUTH have
performed the first-ever computer model simulation of the
structuring of the entire observable universe, from the Big Bang to
the present day.
This first simulation of the standard
model of the universe with a cosmological constant will be followed
by two additional runs focusing on the cosmological evolution of
models with dark energy (4), the mysterious component
introduced to account for the accelerated expansion of the universe
What imprint does dark energy leave on
cosmic structures? And inversely, how can the nature of dark energy
be inferred from observing the distribution of matter in the
These are two fundamental questions that
the project Deus : full universe run will seek to answer.
Simulation of the standard cosmological
model has already allowed researchers to discover a number of
important properties concerning the distribution of matter in the
universe. As an example, they have succeeded in estimating the total
number of galaxy clusters with a mass larger than a hundred thousand
billion solar masses.
These clusters currently amount to 144
The researchers have found that the
first galaxy cluster of this type formed when the universe was only
2 billion years old and the most massive cluster in the observable
universe today weighs 15 quadrillion (or 15 thousand trillion) solar
masses. The data generated by the run has also allowed the
scientists to evaluate spatial distribution of dark matter density
fluctuations in the universe.
These fluctuations have the same origin
as those found in the Cosmic Microwave Background radiation,
resulting from the Big-Bang and observed by the WMAP and Planck
These measurements were obtained in a
simulation covering the entire evolutionary history of the universe
with previously unattained precision and on a much wider range of
scales, from a few millionths to the size of the entire observable
universe. This also revealed with unprecedented accuracy the imprint
of the primordial plasma's acoustic oscillations on the distribution
of dark matter ("Baryon Acoustic Oscillations").
This simulation already seems like a
gold mine of new results for the cosmology community.
The implementation of this exceptional
project would not have been possible without the powerful resources
made available to the researchers by the "Grand Equipement National
de Calcul Intensif " (GENCI) (6), whose new supercomputer
CURIE is equipped with more than 92 000 CPUs and can perform 2
million billion operations per second (2 PFlop/s).
The CURIE supercomputer is housed and
operated by the CEA at the "Très Grand Centre de Calcul," at
Bruyères-le-Châtel (Essonne). Designed by Bull, it is one of the
world's five most powerful supercomputers.
The implementation of Deus - full
universe run represents a new stage in the development of
supercomputing. The first simulation in the project has largely
outperformed the most advanced cosmological simulations carried out
over the past few years by a number of international collaborations
at the largest supercomputing facilities around the world.
The entire project will use more than 30
million hours (about 3500 years) of computing time on virtually all
CPUs of CURIE. More than 150 PBytes of data (the equivalent of 30
million DVDs) are generated throughout the computing runs. Thanks to
an advanced and innovative data reduction process developed by the
researchers, the amount of useful stored data can now be reduced to
In the standard cosmological model with
a cosmological constant, it is now possible to go through the
distribution of dark matter and galaxies across the cosmos over a
distance equivalent to 90 billion light-years (7) and
follow their evolution throughout the entire history of the
The results of these voyages across the
full observable universe, from the present day back to the Big Bang
for the three cosmological models, are expected by late May 2012.
These results will improve current
understanding of the influence of dark energy on the structure of
the universe. They will also provide exceptional support for the
development and interpretation of present and future cosmic
catalogues from major observational projects, especially those
launched by international space agencies.
These include the EUCLID mission
(8), which has been selected by ESA, the European Space
(1) LUTH is a laboratory of
Observatoire de Paris/CNRS/Université Paris Diderot and a
science department of the Paris Observatory.
(2) DEUS : Dark Energy
(3) Jean-Michel Alimi, Pier-Stefano
Corasaniti, Yann Rasera, Irène Balmes, Vincent Bouillot, Vincent
(4) The first model is the
concordance cosmological model characterized by the presence of
a cosmological constant. The second model is characterized by a
dynamical dark energy component, which fills the entire
universe. Finally, the third model mimics a modification of the
law of gravity at large scales by taking into account the
effects of an accelerating component dubbed " phantom " dark
(5) The observational discovery of
the accelerated expansion of the universe of which dark energy
could be the cause was awarded the 2011Nobel Prize in Physics.
(7) In a universe nearly 13.7
billion years old, light travels a distance farther than 13.7
light-years due to the effect of cosmic expansion during travel
time. This distance depends on the cosmological model
considered. Since the space is dilated by the expansion during
travel-time, light covers nearly 45 billion light-years.