"Gang of Four" Receives $500,000 Gruber Cosmology Prize for Reconstructing How the Universe Grew

NEW YORK, June 1, 2011 -

Four astronomers who found a way to recreate the growth of the universe
are the recipients of the 2011 Cosmology Prize of The Peter and Patricia
Gruber Foundation. Marc Davis, a professor in the Departments of Astronomy
and Physics at the University of California at Berkeley; George Efstathiou,
the director of the Kavli Institute for Cosmology in Cambridge; Carlos Frenk,
the director of the Institute for Computational Cosmology at Durham
University; and Simon White, a director of the Max Planck Institute for
Astrophysics in Garching, Germany, will share the $500,000 award.

The official citation recognizes the astronomers — nicknamed the "Gang
of Four" by their colleagues and often collectively abbreviated as DEFW –
for "their pioneering use of numerical simulations to model and interpret the
large-scale distribution of matter in the Universe." The Gruber Prize
recognizes both the discovery method that DEFW introduced as well as the
collaboration's subsequent discoveries.

Davis, Efstathiou, Frenk, and White will each receive an equal share of
the award, along with a gold medal, at a ceremony this fall. They will also
deliver a lecture.

Astronomers have always told us what the universe looks like. Theorists
have always invented ideas as to how it came to look that way. Not until the
computer age, however, could scientists studying the evolution of the entire
universe decisively match the gossamer of educated guesswork with the
blueprint of observational evidence.

The particular evidence that motivated the creation of the DEFW
collaboration came in the form of a 1981 Harvard-Smithsonian Center for
Astrophysics survey of 2400 galaxies at various distances — at the time, an
extraordinary census of how the heavens look on the largest scales. (Davis
led the project.) What the CfA survey showed was an early hint of what is
today called "the cosmic web" — galaxies grouped into lengthy filaments, or
superclusters, separated by vast voids.

Theorists offered two competing ideas that might explain how matter could
have coalesced in such a manner. Both theories took into account the presence
of dark matter, a mysterious substance that astronomers in the 1970s had come
to accept as a necessary piece in the cosmic puzzle in order to explain
galaxy motions that otherwise would be violating the laws of physics. One
candidate theory was "hot dark matter" — "hot" because at early times the
particles would travel at velocities approaching the speed of light. Such
speeding particles leave behind the "regular" matter which makes up galaxies
and so does not clump around them. The other candidate was "cold dark
matter," relatively sluggish particles that would fall together to build
galaxy halos, dragging the regular matter along for the ride.

The Center for Astrophysics survey would allow astronomers to test these
interpretations — but only if they could figure out how to model the
evolution of the universe over billions of years.

Enter the Gang of Four. Although other astronomers had been working with
N-body simulations — so called because they follow a number of points, N,
each representing a concentration of mass — their code couldn't handle a
large enough N to represent large scales in the universe. Efstathiou,
however, suspected that a code used to simulate ionic microcrystals would
work. He succeeded in adapting it for cosmology, and Davis, Frenk, and White
then used that code to demonstrate that a simulated universe based on the hot
dark matter theory didn't remotely match the CfA observations.

Then, in a series of five landmark papers from 1985 to 1988, Davis,
Efstathiou, Frenk, and White showed that observations of galaxies, clusters,
filaments, and voids were consistent with a simulated universe that had
evolved under the influence of cold dark matter.

"The DEFW papers were instrumental in ushering in a new era where
numerical simulations became a standard tool of cosmological studies," says
Wendy Freedman, Crawford H. Greenewalt Chair and Director of The
Observatories of the Carnegie Institution of Washington, and chair of the
2011 Selection Advisory Board to the Gruber Cosmology Prize.

Cold dark matter — or CDM — is today one of the two key components of
the standard cosmological model. The other is the acceleration of the
expansion of the universe, a discovery observers made in the late 1990s that
DEFW's simulations had anticipated. Scientists designate whatever is causing
the acceleration with the mathematical symbol lambda, but it is more commonly
known, in a nod to dark matter, as "dark energy."

Nobody yet knows what dark matter or dark energy are. Yet as more
extensive and more detailed observations of the universe have accumulated,
lambda CDM has become the standard model of cosmology. Today the match
between observation and theory indicates that the universe is composed of 4.6
percent "ordinary" matter, 23.3 percent dark matter, and 72.1 percent dark
energy. Numerical simulations of the kind pioneered by DEFW show that a
universe with this astonishingly precise yet remarkably strange composition
does indeed develop structures which are a close match to those we see around
us.

Additional Information

The official citation reads:

The Peter and Patricia Gruber Foundation proudly presents the 2011
Cosmology Prize to Marc Davis, George Efstathiou, Carlos Frenk and Simon
White for their pioneering use of numerical simulations to model and
interpret the large-scale distribution of matter in the Universe.

Cosmological simulations allow direct confrontation between observation
and theory, and have transformed the way we conceive and visualize the growth
of structure in the Universe.

The work of Professors Davis, Efstathiou, Frenk and White galvanized
support for "cold dark matter" as the dominant form of matter in the Universe
and has thus been instrumental in the crafting of our current cosmological
paradigm.

The Gruber International Prize Program honors contemporary individuals in
the fields of Cosmology, Genetics, Neuroscience, Justice and Women's Rights,
whose groundbreaking work provides new models that inspire and enable
fundamental shifts in knowledge and culture. The Selection Advisory Boards
choose individuals whose contributions in their respective fields advance our
knowledge, potentially have a profound impact on our lives, and, in the case
of the Justice and Women's Rights Prizes, demonstrate courage and commitment
in the face of significant obstacles.

The Peter and Patricia Gruber Foundation honors and encourages
educational excellence, social justice and scientific achievements that
better the human condition. For more information about Foundation guidelines
and priorities, please visit www.gruberprizes.org.

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