Big Bang – the beginning of time
The scientists who study the universe, or the cosmos, are called cosmologists, and the cosmologists who think about how the universe began, how the universe changed and developed, and how it is right now and will be in the future, are using ideas and experiments to imagine and test their theories.
The biggest idea around at the moment about the origin of the universe is called the Big Bang Theory.
The ‘Big Bang’ theory of the origin of the Universe got its name from Sir Fred Hoyle, who refused to believe the developing idea that all the matter of the Universe was packed into an incredibly small, hot, dense sphere, that exploded into what became our expanding Universe. How could all of creation come from just a “big bang”?
In 1927 a Belgian astronomer and cosmologist , Georges Lemaitre, came up with the idea of an expanding universe, before astronomers had even discovered that this expansion of the universe was a fact, and at a time when most cosmologists thought the Universe was static, or what Sir Fred Hoyle described much later as being in a ‘steady state’.
It was Lemaitre that realized if galaxies were moving apart over time, then in the past they must have been closer together. He also speculated that even before that there must have been a point in time and space where a sort of ‘primeval atom’, about 30 times the size of the Sun, exploded.
Lemaître’s Big Bang theory was advocated and developed by George Gamow, who introduced the theory of big bang nucleosynthesis and whose associates, Ralph Alpher and Robert Herman, predicted the cosmic microwave background radiation.
In 1964, Arno Penzias and Robert Wilson accidentally discovered the cosmic background radiation while conducting diagnostic observations using a new microwave receiver owned by Bell Laboratories. Their discovery provided substantial confirmation of the general cosmic microwave background predictions—the radiation was found to be isotropic and consistent with a blackbody spectrum of about 3 K—and it pitched the balance of opinion in favor of the Big Bang hypothesis. Penzias and Wilson were awarded a Nobel Prize for their discovery.
In 1989, NASA launched the Cosmic Background Explorer satellite (COBE), and the initial findings, released in 1990, were consistent with the Big Bang’s predictions regarding the cosmic microwave background. In early 2003, the first results of the Wilkinson Microwave Anisotropy Probe (WMAP) were released. This spacecraft also disproved several specific cosmic inflation models, but the results were consistent with the big bang inflation theory, it confirms too that a sea of cosmic neutrinos permeates the Universe, a clear evidence that the first stars took more than a half-billion years to create a cosmic fog. A new space probe named Planck, with goals similar WMAP, was launched in May 2009. It is anticipated to soon provide even more accurate measurements of the cosmic microwave background.