Nature is characterized by a number of physical laws and fundamental dimensionless couplings. These determine the properties of our physical universe, from the size of atoms, cells and mountains to the ultimate fate of the universe as a whole. It is rather remarkable how little we know about them.
The constancy of physical laws is one of the cornerstones of the scientific research method, but for fundamental couplings this is an assumption with no other justification than a historical assumption.
There is no "theory of constants" describing their role in the underlying theories and how they relate to one another or how many of them are truly fundamental.
Studying the behaviour of these quantities throughout the history of the universe is an effective way to probe fundamental physics. This explains why ESA and ESO include varying fundamental constants among their key science drivers for the next generation of facilities.
Ample experimental evidence shows that fundamental couplings run with energy (in ways that tightly constrain high energy physics models), and many particle physics and cosmology models suggest that they should also roll with time. Recent scientific and technological developments, mostly originated within Europe, gave us tools to test this hypothesis across the cosmic ages.
Laboratory studies can determine the numerical value of the fundamental constants and their rate of change over intervals of a few years. Current measurements are consistent with no variation, but the potential to tighten this constraint must be exploited.
Astronomical observations allow us to study a range of physical processes throughout the history of the universe, which depend on the values of the fundamental constants. ESO's VLT is playing a key role in measurements of the fine-structure constant α and the proton-to-electron mass ratio µ over 80% of the age of the universe. Many other observables, which probe a wide range of cosmic epochs, are sensitive to variations: the best examples are the Cosmic Microwave Background and Primordial Nucleosynthesis.
Confirmation of the rolling of dimensionless constants implies a violation of the Einstein Equivalence Principle, pointing to yet undiscovered gravitational physics. Any Grand-Unified Theory predicts a specific relation between variations of α and µ, and simultaneous measurements of both provide key consistency tests. A connection between the variation of fundamental parameters and the nature of dark energy could be tested or unveiled.
Even null measurements have a strong impact. The natural timescale for a cosmological mechanism is the Hubble time, but current laboratory bounds already restrict any present-day variation of α to six orders of magnitude lower - which severely constrains cosmological and particle physics models.
Several groups from Europe and outside are independently engaged in this endeavour. While most measurements are consistent with no rolling, some published reports do suggest variations of α and µ. These are encouraging but far from being proved, and due to the potential implications it is crucial to shed light on this controversy.
The first international meeting devoted to this topic was held during JENAM2002. This had a strong impact on subsequent developments. After eight years the field has considerably matured and it is time for a new assessment in the European countries. We will bring together the most active researchers in this area to discuss the latest developments, explore ways to leverage the unique capabilities of the various groups and create synergies with European facilities such as ESO's VLT (and the future E-ELT), ESA's Planck and Herschel spacecrafts, as well as ALMA, in which Europe plays a leading role.
Registrations, abstract submissions and grant requests must be done through the main JENAM page.
John D. Barrow (Cambridge, UK)
Enrique García-Berro (UPC, Spain)
Sergei Levshakov (Ioffe Inst., Russia)
Carlos Martins (CAUP, Portugal)
João Magueijo (Imperial College, UK)
Paolo Molaro (INAF-Trieste, Italy)
Michael Murphy (Swinburne, Australia)
Keith Olive (Minnesota, USA)
Ekkehard Peik (PTB, Germany)
Patrick Petitjean (IAP, France)
Dieter Reimers (Hamburg Obs., Germany)
Rodger Thompson (Steward Obs., USA)
Wim Ubachs (VU, The Netherlands)
John Webb (New South Wales, Australia)
Carlos Martins (CAUP)
Paolo Molaro (Trieste)
Manuel Monteiro (CAUP - Sysadmin)
Elsa Silva (CAUP - Admin)