07 February 2006
Theme 3 - What are the fundamental physical laws of the Universe?
The most important challenge facing fundamental physics today is to understand the foundations of nature more deeply. Physicists know that the laws of physics as formulated at present do not apply at extremely high temperatures and energies, so that events in the first fraction of a second after the Big Bang are not at all understood. Matter as we know it today did not then exist; protons and electrons formed later.
Yet whatever happened during this first instant created the conditions that led to everything we see today: atoms, stars, galaxies and people. Many physicists believe that in these extreme conditions physics was governed by the 'ultimate theory', a single theory that explains and unifies all the separate laws and forces as they appear today.
| During the period 2015-2025 it will be possible to use several maturing technologies to conduct experiments in space to look for the slight deviations in our standard physical laws that might contain crucial clues to the deeper unified theory of physics that physicists seek. The European fundamental physics community responded to the Cosmic Vision initiative with an outpouring of suggestions for high-precision experiments in space aimed at the areas felt most likely to uncover new physics. |
Probe the limits of general relativity, symmetry violations, fundamental constants, short-range forces, quantum physics of Bose-Einstein condensates, and ultra-high-energy cosmic rays, to look for clues to unified theories
- Use the stable and gravity-free environment of space to implement high-precision experiments to search for tiny deviations from the standard model of fundamental interactions
- Test the validity of Newtonian gravity using a trans-Saturn dragfree mission
- Observe from orbit the patterns of light emitted from the Earth's atmosphere by the showers of particles produced by the impacts of sub-atomic particles of ultra-high-energy
- Fundamental physics explorer programme
- Deep space gravity probe
- Space detector for ultrahigh-energy cosmic rays
| Gravitational waves were predicted by Einstein almost immediately after he formulated his theory of general relativity 90 years ago. They have the potential to bring us completely new information about the Universe and its most extreme objects. Observable gravitational waves should be produced by massive objects (especially black holes) colliding or moving in tight orbits around one another, by the Big Bang, and possibly by unknown components of the dark matter of the Universe. |
| Goal |
Make a key step towards detecting and studying the gravitational radiation background generated at the Big Bang. Probe the Universe at high redshift and explore the dark Universe
- Primordial gravitational waves, unaffected by ionised matter, are ideal probes of the laws of physics at the fantastic energies and temperatures of the Big Bang. They open an ideal window to probe the very early Universe and dark energy at very early times
- Gravitational wave cosmic surveyor
| Black holes are the most exotic prediction of general relativity. They have the strongest possible gravitational fields, and yet in general relativity they are among the simplest objects to describe. The entire gravitational field of a black hole is determined by just three parameters: its total mass, its total spin angular momentum, and its total electric charge. It is as if extreme gravity crushes the individuality out of these objects, so that they are all essentially identical, regardless of how they were formed. Gravitational wave detectors, especially LISA, will register gravitational waves from disturbed black holes and from objects orbiting black holes, and they will be able to test whether real black holes are as simple as relativity predicts. |
| Goal |
Probe general relativity in the environment of black holes and other compact objects, and investigate the state of matter inside neutron stars
- The study of the spectrum and time variability of radiation from matter near black holes shows the imprint of the curvature of space-time as predicted by general relativity. This has strong implications for astrophysics and cosmology in general
- Large-aperture X-ray observatory