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In the case of accelerated expansion, ¨ is positive; therefore, ˙ was smaller in the past than today. Thus, an accelerating universe took a longer time to expand from 2/3 to 1 times its present size, compared to a non-accelerating universe with constant ˙ and the same present-day value of the Hubble constant. This results in a larger light ...
As the universe expands and the matter in it thins, the gravitational attraction decreases (since it is proportional to the density), while the cosmological repulsion increases. Thus, the ultimate fate of the ΛCDM universe is a near-vacuum expanding at an ever-increasing rate under the influence of the cosmological constant.
The Big Bang event 13-14 billion years ago initiated the universe, and it has been expanding ever since. Scientists in 1998 disclosed that this expansion was actually accelerating, with dark ...
It appears to be expanding faster today than it did in the past. For years, scientists have been troubled by an unusual feature of our universe. It appears to be expanding faster today than it did ...
Something is changing the expansion rate of the universe, scientists have said. For decades, researchers have been attempting to measure the “Hubble constant”, or the speed at which the cosmos ...
The four-dimension universe lies on one of the branes. The collision corresponds to the Big Crunch, then a Big Bang. The matter and radiation around us today are quantum fluctuations from before the branes. After several billion years, the universe has reached its modern state, and it will start contracting in another several billion years.
By doing so, the researchers hope to uncover fresh clues about how fast the universe is expanding and, just maybe, whether life could exist anywhere else in the universe.
In 1922, Alexander Friedmann derived his Friedmann equations from Einstein field equations, showing that the universe might expand at a rate calculable by the equations. [24] The parameter used by Friedmann is known today as the scale factor and can be considered as a scale invariant form of the proportionality constant of Hubble's law. Georges ...