Page 144 - Encyclopedia Of World History Vol V

universe, origins of 1921

The one who walks the way of truth
creates life. • Sumerian Proverb

some time in the past, it must have been infinitely small. apparent was that the early universe was very different
Hubble’s observations might have seemed little more from the universe of today. Clearly, the universe had
than a curiosity if it had not been for the fact that Albert changed over time, as the big bang theory implied.
Einstein (1879–1955), in his General Theory of Relativ- Even more important was the discovery, in 1965, of
ity (1916), had also posited that the universe might be cosmic background radiation, by two American scientists,
either expanding or contracting.At first, Einstein resisted Arno Penzias (b. 1933) and Robert Wilson (b. 1936). In
this conclusion, but by the late 1920s, he had been per- trying to construct an extremely sensitive radio antenna,
suaded by the work of a young Russian mathematician, they found a persistent hum of weak energy coming from
Alexander Friedmann (1888–1925) that the universe, all directions in space. Energy coming from a particular
like a pin standing on end, was unlikely to be entirely sta- place in space made sense, but they could imagine no
ble. In reality, it was much more likely to be either force that could generate energy from all parts of the uni-
expanding or contracting, and Hubble’s evidence sug- verse, until someone told them that this was exactly what
gested it was expanding. the big bang theory predicted. Attempts to model the
early history of the universe had suggested that as the uni-
The Big Bang Theory verse cooled there would come a point when protons and
Despite both observational and theoretical findings, the electrons could combine to form atoms. Atoms, unlike
idea of an expanding universe remained little more than naked protons and electrons, are electrically neutral, so as
an intriguing hypothesis until after the Second World atoms formed most of the matter in the universe lost its
War. Theorists such as the Russian-American physicist electric charge.At that point, matter and energy would in
and astronomer Arthur Gamow (1904–1968) and the effect become disentangled, and energy would be free for
British astronomer Fred Hoyle (1915–2001) worked on the first time to travel at will through the universe. Early
the implications of an expanding universe and found that big bang theorists had suggested that this sudden release
it was possible to construct a surprisingly coherent pic- of energy ought to be observable even today, and it was
ture of how matter might have behaved under the soon clear that this was exactly what Penzias and Wilson
extreme heat and pressure at the very beginning of the had detected.The steady state theory had no explanation
universe’s history. Nevertheless, for a time, the big bang for cosmic background radiation, but the big bang theory
theory had to compete with an alternative theory, the so- seemed to explain it naturally. The discovery of cosmic
called steady state theory, developed by Hoyle and oth- background radiation was a knockout blow to the steady
ers in the 1950s. (Indeed, it was Hoyle, one of the state theory; ever since, the big bang theory has provided
fiercest critics of the big bang theory, who coined the the core idea, or paradigm, of modern cosmology.
phrase “big bang,” in a lecture in 1950.) In an attempt to
preserve the idea of an eternal, and essentially unchang- Big Bang Cosmology
ing, universe, the steady state theory suggested that mat- Working out the details of big bang cosmology remains
ter was continually being created throughout the universe a complex task, but no other theory comes close to
at just the rate needed to counteract the apparent rate of explaining as much, so few cosmologists doubt that it is
expansion. The steady state theory implied that the uni- essentially right, even if some of its details may need to
verse had always been much as it is today, a hypothesis be modified in the future. One reason for this confidence
that was soon tested. By the early 1960s, improvements is that new evidence for the theory has emerged since the
in radio astronomy enabled astronomers to make more 1960s.As the power of telescopes has increased, astrono-
careful studies of remote galaxies. Because light takes a mers have found that the most remote parts of the uni-
finite time to travel, such studies were, in effect, examin- verse are indeed very different from those closest to us,
ing the universe in its youth, and what soon became and those differences fit very well with what big bang cos-