Ripples in Cosmic Neutrino Background Measured for the First Time
RAS Communications Officer
issued by RAS Communications
June 15, 2005 Birmingham, UK -- Astrophysicists from the Universities of Oxford
and Rome have for thefirst time found evidence of ripples in the
Universe's primordial sea of neutrinos, confirming the predictions of both Big Bang theory
and the Standard Model of particle physics.
Neutrinos are elementary particles with no charge and very little mass,
which are extremely difficult to study due to their very weak interaction
with matter. Yet pinning down the physical properties of neutrinos is of
paramount importance to scientists attempting to understand the
fundamental building blocks of Nature. According to the standard Big Bang
model, neutrinos permeate the Universe at a density of about 150 per cubic
centimetre. The Earth is therefore immersed in an ocean of neutrinos,
without us ever noticing.
Although it is impossible to measure this "Cosmic Neutrino Background"
directly with present-day technology, physicists predict that ripples or
waves in it have an impact on the growth of structures in the Universe.
In research to be published in the journal Physical Review Letters, Dr.
Roberto Trotta, Lockyer Fellow of the Royal Astronomical Society at
Oxford's Department of Physics, and Dr. Alessandro Melchiorri of La
Sapienza University in Rome were able to demonstrate for the first time
the existence of ripples of primordial origin in the Cosmic Neutrino
The discovery, made by combining data produced by the NASA WMAP (Wilkinson
Microwave Anisotropy Probe) satellite and the Sloan Digital Sky Survey,
confirms the predictions of both the Big Bang theory and the Standard
Model of particle physics. The research has important implications for the
study of neutrinos, showing that theories of the infinitely large
(cosmology) and the infinitely small (particle physics) are in agreement.
Dr. Trotta said: "This research provides important new evidence in favour
of the current cosmological model, unifying it with fundamental physics
theories. Cosmology is becoming a more and more powerful laboratory where
physics not easily accessible on Earth can be tested and verified. The
high quality of recent cosmological data allows us to investigate
neutrinos in the cosmological framework, obtaining measurements which are
competitive with -- if not superior to -- particle accelerator findings."