SOME research tools change the face of science. Take the Super Proton Synchrotron at Europe鈥檚 CERN particle physics centre. In 1983, it detected the W and Z particles, confirming that two of the fundamental forces of nature were actually one. Ten years later, NASA鈥檚 Cosmic Background Explorer (COBE) found ripples in the radiation left by the big bang, revealing the seeds of structure in our Universe. Now comes the Microwave Anisotropy Probe (MAP), COBE鈥檚 heir, with findings that change cosmology even more profoundly.
Criticism has been heaped on cosmology for being better endowed with untestable ideas than measurable facts 鈥� and not only by those outside the discipline. 鈥淲hen I started my PhD as a theoretical cosmologist, you could say anything you wanted,鈥� joked Jo茫o Magueijo of Imperial College, London. 鈥淭hen COBE went up. It鈥檚 been a disaster.鈥� MAP will be even more of a disaster for the hand-wavers because it will pin down many of the numbers essential to cosmology (see 鈥淥ur Universe in glorious detail鈥�).
These findings will transform cosmology. Some wilder theories will fail the test. Questions about how old the Universe is, how fast it is expanding and what shape it is will be superseded by the question of how all these properties came to be so. The focus will shift towards the physics of the very young Universe, when it was between 10鈭�33 and 10鈭�15 seconds old and the rapid expansion called inflation is supposed to have taken hold.
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Whatever caused inflation is likely to be found on those other wild shores of theoretical physics, string theory and quantum gravity. And for it all to make sense in the end, the force field that inflated the Universe and put the bumps on MAP鈥檚 mottled image must be a sensible physical thing, a field that is implicit in whatever theory successfully describes the forces and particles of nature.
Some questions will stay the same. What is the nature of dark matter and dark energy? Is the Universe infinite? But the chances are that all these will turn out to be intimately related to what went on in those first yoctoseconds.
The way to reach back to this time is by gathering more data, and better. So observational cosmologists will still count galaxies to compare them with the ripples on MAP鈥檚 images, fly microwave detectors on balloons, and design space-based observatories. In 2007 or thereabouts, Europe will launch an even sharper-eyed microwave probe called Planck. But for now, MAP will give cosmology the confidence boost it needs. The old uncertainties are dead, bring on the new.