The Big Bang Theory

Read the text and fill in gaps (1‑10) with the correct variant (A, B, C or D).

The Big Bang theory is the prevailing cosmological model of the early ___(1)___ of the universe. The major premise of the Big Bang theory is that the universe was once in an ___(2)___ hot and dense state that expanded rapidly (a "Big Bang"). This rapid expansion ___(3)___ the young universe to cool and resulted in its present continuously expanding state. According to recent measurements, scientific evidence, and observations, the original state happened around 13.7 billion years ago, which can be referred ___(4)___ as the time that the Big Bang occurred.

Georges Lemaître proposed what became known as the Big Bang theory of the ___(5)___ of the Universe; he called it his "hypothesis of the primeval atom". The framework for the model relies on Albert Einstein's general relativity and on simplifying assumptions (such as homogeneity and isotropy of space). The governing equations had been formulated ___(6)___ Alexander Friedmann. In 1929, Edwin Hubble discovered that the distances to far away galaxies were generally proportional to their redshifts – an idea originally suggested by Lemaître in 1927. Hubble's observation was taken to indicate that all very distant galaxies and clusters have an apparent velocity directly away from our vantage point: the farther away, ___(7)___ the apparent velocity.

If the distance between galaxy clusters is increasing today, everything must have been closer together in the past. This idea has been considered in detail back in time to extreme densities and temperatures, and large particle accelerators have been built to experiment on and test such conditions, resulting in significant confirmation of this theory. On ___(8)___ hand, these accelerators have limited capabilities to probe into such high energy regimes. There is little evidence regarding the absolute earliest instant of the expansion. Thus, the Big Bang theory cannot and does not provide any explanation for such an initial condition; rather, it describes and explains the general evolution of the universe going forward from that point on. The observed abundances of the light elements throughout the cosmos closely match the calculated predictions for the formation of these elements from nuclear processes in the ___(9)___ expanding and cooling first minutes of the universe, as logically and quantitatively detailed according to Big Bang nucleosynthesis.

Fred Hoyle is credited with coining the term Big Bang during a 1949 radio broadcast. It is popularly reported that Hoyle, who favored an alternative "steady state" cosmological model, intended this to be pejorative, but Hoyle explicitly denied this and said it was just a striking image ___(10)__ to highlight the difference between the two models. After the discovery of the cosmic microwave background radiation in 1964, and especially when its spectrum (i.e., the amount of radiation measured at each wavelength) was found to match that of thermal radiation from a black body, most scientists were fairly convinced by the evidence that some version of the Big Bang scenario must have occurred.

1.	a. construction	b. development	c. origin	d. working out
2.	a. extremely	b. very	c. fairly	d. rather
3.	a. has caused	b. had caused	c. was caused	d. caused
4.	a. to	b. with	c. in	d. by
5.	a. construction	b. development	c. working out	d. origin
6.	a. with	b. by means	c. by	d. on
7.	a. the highest	b. highest	c. higher	d. the higher
8.	a. other	b. the other	c. another	d. the another
9.	a. rapid	b. rapidly	c. fastly	d. quick
10.	a. mean	b. means	c. meant	d. meaned

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