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Europeans unite to tap early universe for secrets of fundamental physics

Aim to produce new generation of astronomer that understands theory and observation

The future of fundamental physics research lies in observing the early universe and developing models that explain the new data obtained. The availability of much higher resolution data from closer to the start of the universe is creating the potential for further significant theoretical breakthroughs and progress resolving some of the most difficult and intractable questions in physics. But this requires much more interaction between astronomical theory and observation, and in particular the development of a new breed of astronomer who understands both.

This was the key conclusion from a recent workshop organised by the European Science Foundation (ESF), bringing together experts in cosmology, astrophysics and particle physics. “I think the realization of how important this is, and of how much needs to be done to get to that stage, will be the main long-term legacy of the workshop,” noted Carlos Martins, convenor of the ESF workshop. “In particular, a lot of work needs to be done in order to provide a stronger 'theoretical underpinning' for future observational work. Ultimately this means that when training the next generation of researchers in this area, a lot more effort needs to be put into forming 'bilingual' researchers, that are fluent both in the language of observations and in that of theory.”

In effect astronomy is returning to its roots, since the early great discoveries were made by the likes of Galileo for whom theory and observation were two sides of the same coin. The field subsequently split into two, with theorists and observers becoming divorced and ceasing to communicate effectively with each other. Now though the emergence of highly sophisticated observing platforms, capable of making different types of measurement depending on theoretical considerations, means that the two are once again becoming closely entwined.

Two key developments are the ability to take the observing instruments into space, where more accurate observations can be made beyond the influence of the earth’s atmosphere and magnetic field, and availability of high precision atomic clocks for measurement of timing down to nanoseconds. At the same time it has become clear there is a limit to how much can be discovered in earth-bound laboratories, even those as big as the Large Hadron Particle Accelerator run by CERN, the European Organization for Nuclear Research, in Switzerland. The early universe on the other hand is a natural laboratory with the required scale and energy, providing the potential for probing deeper into fundamental processes relating to matter and energy. “The idea was to bring together the top European expertise in cosmology, astrophysics and particle physics, get the various sub-communities to be aware of what is being done 'elsewhere', and focus our efforts on using the early universe as a laboratory in which we can probe fundamental physics - in ways that we'll never be able to do if we restrict ourselves to laboratory tests,” said Martins.

The workshop also discussed some of the fundamental questions that these new observations could help resolve, notably whether or not scalar fields exist across the whole the universe. Unlike say gravitational or magnetic fields, which have both strength and direction, scalar fields have strength alone, varying from point to point. They definitely exist within some closed systems, such as the temperature distribution within the earth’s atmosphere, but it is not yet known whether they exist on the scale of the universe. As Martins pointed out, this is a vital question because the existence of scalar fields could help explain how the universe developed after the Big Bang and became as we observe it today. For example scalar fields could explain the existence of dark matter and energy, which can only be observed indirectly from their gravitational effects on the part of the universe we can see.

New observations could also help confirm aspects of current theories, such as the existence of gravitational waves as predicted by Einstein’s General Relativity. Gravitational waves are supposed to be ripples through space time radiating outwards from a moving object. However the ripples are so small as to be very difficult to measure, with the only observational evidence so far coming from pulsars, which are very dense binary neutron stars revolving around each other. The revolution of pulsars appears to slow down in a manner consistent with the existence of gravitational waves causing them to lose energy, but further confirmation is needed.

Finally there is also the prospect of making further progress in the field of astronomy itself, for example by using space borne atomic clocks to calibrate advanced spectrographs that in turn will be used to search for “extra-solar” planets in neighbouring star systems.

The workshop, Astrophysical Tests Of Fundamental Physics was held in March 2008 in Porto, Portugal. www.astro.up.pt/esf2008