BEST IELTS Academic Reading Test 481

BEST IELTS Academic Reading Test 481

IELTS Academic Reading Test

Big Bang Theory

A. The Big Bang theory is an astrophysical model for the visible universe from the earliest known stages through its successive large-scale development. The model labels how the universe extended from a very high-density and high-temperature state, and bids a comprehensive clarification for a wide range of phenomena, including the plenty of light elements, the cosmic microwave background (CMB) radiation, large-scale structure and Hubble’s law (the farther away galaxies are, the faster they are moving away from Earth).

If the pragmatic conditions are induced back in time using the identified laws of physics, the forecast is that just before a period of very high density there was a distinctiveness which is characteristically related with the Big Bang. Current knowledge is deficient to regulate if the distinctiveness was primeval.

IELTS Academic Reading Test

B. Georges Lemaître first noted in 1927 that a growing universe could be outlined back in time to an initiating single point, calling his theory that of the “primeval atom”. For much of the rest of the 20th century scientific community was alienated amid supporters of the Big Bang and the rival stable state model, but a wide range of empirical evidence has sturdily favoured the Big Bang which is now universally acknowledged.

Edwin Hubble discovered that galaxies are wandering apart in 1929 from analysis of galactic redshifts; this is vital observational evidence for an expanding universe. In 1964, the CMB was exposed, which was vital evidence in favour of the hot Big Bang model, since that theory forecast the presence of background radiation throughout the universe. The known laws of physics can be used to compute the features of the universe in detail back in time to an early state of extreme density and temperature.

IELTS Academic Reading Test

C. Thorough measurements of the expansion rate of the universe place the Big Bang at around 13.8 billion years ago, which is thus measured the age of the universe. After its initial expansion, the universe cooled adequately to let the creation of subatomic particles, and later atoms. Massive clouds of these primordial elements (mostly hydrogen, with some helium and lithium) later merged through gravity, finally founding early stars and galaxies, the descendants of which are noticeable today.

Astronomers also detect the gravitational effects of dark matter surrounding galaxies. Most of the matter in the universe appears to be in the form of dark matter, and the Big Bang theory and various observations specify that it is not conventional baryonic matter (atoms). It is still not known precisely what dark matter is. More lately, measurements of the redshifts of supernovae specify that the expansion of the universe is hastening, an observation credited to dark energy’s presence.

IELTS Academic Reading Test

D. The Big Bang theory proposals an inclusive clarification for a wide range of observed phenomena, including the profusion of light elements, the CMB, large-scale structure, and Hubble’s law. The theory hinge on two main conventions: the universality of physical laws and the cosmological principle. The universality of physical laws is the fundamental principle of the theory of relativity. The cosmological principle statuses that on large scales the universe is consistent and isotropic. The cosmological principle statuses that on large scales the universe is consistent and isotropic.

E. These ideas were initially taken as hypothesizes, but later efforts were made to test each of them. For example, the first supposition has been tested by observations viewing that main possible deviation of the fine-structure constant over much of the age of the universe is of order 10-5. Also, general relativity has approved severe tests on the scale of the Solar System and binary stars.

IELTS Academic Reading Test

F. The large-scale universe appears isotropic as observed from Earth. If it is certainly isotropic, the cosmological principle can be derivative from the simpler Copernican principle, which positions that there is no favoured (or special) observer or vantage point. To this end, the cosmological principle has been confirmed to a level of 10-5 via observations of the temperature of the CMB. The universe has been measured to be consistent on the largest scales at the 10% level.

G. The extension of the Universe was reliant from the early astronomical observations and is an essential element of the Big Bang theory. Mathematically, general relativity tags spacetime by a metric, which controls the distances that separate nearby points. The points, which can be galaxies, stars, or other objects, are themselves specified using a coordinate chart or “grid” that is laid down over all spacetime. The cosmological principle proposes that the metric should be consistent and isotropic on large scales, which distinctively singles out the Friedmann-Lemaître-Robertson-Walker metric (FLRW).

IELTS Academic Reading Test

This metric comprises a scale factor, which defines how the size of the universe changes with time. This allows a convenient choice of a coordinate system to be made, called comoving coordinates. In this coordinate system, the grid enlarges along with the universe, and objects that are moving only because of the expansion of the universe, endure at fixed points on the grid. While their coordinate distance (co-moving distance) remains persistent, the physical distance between two such co-moving points swells proportionally with the scale factor of the universe.

H. The Big Bang is not an explosion of matter moving outward to fill an empty universe. Instead, space itself enlarges with time everywhere and upsurges the physical distances amid comoving points. In other words, the Big Bang is not an explosion in space, but by somewhat an increase of space. Because the FLRW metric assumes an even dispersal of mass and energy, it smears to our universe only on large scales-local concentrations of matter such as our galaxy are gravitationally bound and as such do not experience the large-scale expansion of space.

IELTS Academic Reading Test

Which paragraph contains the following information?

Write correct letter A-H in your answer sheet.

15. How large-scale universe looks from earth.

16. Testing the ideas of the solar system and binary stars using general relativity.

17. Big bang, not an explosion, but an expansion in space.

18. How old our universe is?

19. Law and a principle proving that universe is consistent and isotropic.

20. Despite previous denials, Big band theory is now widely acceptable.

21. Terms and calculations used to measure nearby stars and galaxies.

22. A theory suggesting that how our universe extended from a high-density and high-temperature state.

IELTS Academic Reading Test

Do the following statements agree with the information given in the Reading Passage?

YES – If the statement agrees with the claims of the writer

NO – If the statement contradicts the claims of the writer

NOT GIVEN – If it is impossible to say what the writer thinks about this

23. Big bang theory has many opponents in today’s era.

24. In 1929, Edwin Hubble observed that the galaxies are shrinking into each other.

25. The exact time when Big bang happened is not known.

26. The constituents of dark matter have been proved.

27. Big bang is a large-scale expansion of space, not an explosion.

IELTS Academic Reading Test

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BEST IELTS Academic Reading Test 481

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IELTS Academic Reading Test

15. F

16. E

17. H

18. C

19. D

20. B

21. G

22. A

23. NO

24. NO

25. YES

26. NO

27. YES

IELTS Academic Reading Test

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