The real Big Bang Theory
As Peebles and his Princeton team rushed to complete their discovery in 1964, they were scooped by two young scientists at nearby Bell Labs, Arno Penzias and Robert Wilson. The remaining radiation from the Big Bang was predicted to be microwave energy, in much the same form used by countertop ovens.
It was a serendipitous finding because Penzias and Wilson had constructed an antenna to detect this microwave radiation which was used in satellite communications. But they were mystified by a persistent source of noise in their measurements, like the fuzz of a radio tuned between stations.
Penzias and Wilson talked to Peebles and his colleagues and learned that this static they were hearing was the radiation left over from the Big Bang itself. Penzias and Wilson won the Nobel Prize in 1978 for their discovery, though Peebles and his team provided the crucial interpretation.
Peebles has also made decades of pivotal contributions to the study of the matter which pervades the cosmos but is invisible to telescopes, known as dark matter, and the equally mysterious energy of empty space, known as dark energy. He has done foundational work on the formation of galaxies, as well as to how the Big Bang gave rise to the first elements – hydrogen, helium, lithium – on the periodic table.
Finding planets beyond our solar system
For their Nobel Prize-winning work, Mayor and Queloz carried out a survey of nearby stars using a custom-built instrument. Using this instrument, they could detect the wobble of a star – a sign that it is being tugged by the gravity of an orbiting exoplanet. In 1995, in a landmark discovery published in the journal Nature, they found a star in the constellation Pegasus rapidly wobbling across the sky, in response to an unseen planet with half the mass of Jupiter. This exoplanet, dubbed 51 Pegasi b, orbits close to its central star, well within the orbit of Mercury in our own solar system, and completes one full orbit in just four days.
This surprising discovery of a “hot Jupiter,” quite unlike any planet in our own solar system, excited the astrophysical community and inspired many other research groups, including the Kepler space telescope team, to search for exoplanets.
These groups are using both the same wobble detection method as well as new methods, such as looking for light dips caused by exoplanets passing over nearby stars. Thanks to these research efforts, more than 4,000 exoplanets have now been discovered.