Planck: The future of probing the past
During inflation, quantum fluctuations in space-time were extended to cosmological scales: by the time the CMB was released, these fluctuations had led to variations in the distribution of matter across the universe. Denser regions of the universe produced CMB photons slightly colder than average, and vice versa.
Planck will create the sharpest possible map of all the CMB's anisotropies, and will arguably provide the final word on their distribution (see "computer simulation, above right"). "It is the Everest excuse - we are going to get everything because it's there," says cosmologist Andrew Jaffe of Imperial College London.
By measuring these temperature variations accurately, cosmologists can calculate parameters such as the curvature of space-time, and the contribution of dark energy, dark matter and normal matter to the distribution of mass and energy in the universe. Planck will slash the uncertainties in the values of these parameters to less than 1 per cent. "In terms of the information that is available to do cosmology, Planck is about 15 times better than WMAP," says Jan Tauber, Planck's project scientist at ESA's offices in Noordwijk, the Netherlands.