James Peebles |
The 2019 Nobel Prize in Physics has been assigned to
cosmology and divided among three scientists: James Peebles, a Canadian, who
receives half the prize for his theoretical work; and Michel Mayor and Didier
Queloz, who have shared the other half for having discovered the first planet
outside the solar system that revolves around a star in the main sequence.
The theory of the Big Bang was proposed in 1931 by George Lemaître, as
a consequence of the extension to the past of the Hubble-Lemaître
law. In 1948, Ralph Alpher and Robert Herman predicted that, if the Big
Bang theory is correct, there must be a cosmic background
radiation with a temperature close to 5 Kelvin. In 1965 Arno Penzias and
Robert Wilson discovered the existence of such cosmic radiation, whose
temperature turned out to be close to 3 Kelvin. That same year, Robert Dicke,
James Peebles and other collaborators reasoned that the radiation discovered by
Penzias and Wilson is precisely the signature of
the Big Bang predicted by Alpher and Herman. During the 70s,
Peebles was one of the leading theoretical cosmologists who studied the field
of the formation of the great cosmic structures (galaxies and groups of
galaxies). For these works he has now been awarded the Nobel Prize.