Final answer:
The "Big Crunch" is a hypothetical collapse of the universe, serving as an opposite concept to the Big Bang. To simulate it, a closed universe model without dark energy is used, where gravity eventually causes a contraction. However, the existence of dark energy makes the continual expansion of the universe more likely.
Step-by-step explanation:
The "Big Crunch" is a theoretical scenario where the universe's expansion halts and reverses, leading to a catastrophic collapse of all matter, energy, space, and time. According to the noted physicist John Wheeler, the Big Crunch would be an implosion, where everything is crushed out of existence. This hypothetical event is the antithesis to the Big Bang, which describes the universe's beginnings as a rapid expansion from a singular point.
To simulate the Big Crunch using a theoretical model, one would consider a universe where the actual density is greater than the critical density, and there is an absence of dark energy. In such a closed universe, gravity would eventually overpower the expansion, causing the universe to contract and culminate in the Big Crunch. This simulation which illustrates the Big Bang, leading all matter and space to coalesce back into an infinitely small point.
The discovery of dark energy has cast doubt on the Big Crunch scenario. Dark energy is causing the universe to expand at an accelerated rate, suggesting that a continual expansion is more likely than a gravitational collapse. Nonetheless, exploring the Big Crunch as a concept can elucidate the conditions necessary for such a collapse and expand our understanding of cosmological models beyond the Standard Big Bang Model.