1. Origins in the Big Bang:
    • The Big Crunch theory originates from the concept of the universe's birth, the Big Bang. Some astrophysicists predict that the universe will ultimately collapse in a reverse of its initial expansion.
  2. Concept of the Big Crunch:
    • According to the Big Crunch scenario, the gravitational pull of matter counteracts the cosmic expansion, causing the universe to eventually stop expanding, reverse direction, and collapse inward.
  3. Contraction of the Universe:
    • As gravity pulls matter inward, the universe contracts, compressing into a superhot, super-dense singularity resembling its original state, potentially leading to the obliteration of all existing stars and galaxies.
  4. Role of Dark Energy and Matter:
    • Dark energy, an enigmatic force, opposes gravity, driving the universe's expansion. If dark energy accelerates expansion beyond expectations, it could prevent the universe from collapsing in a Big Crunch.
  5. Data and Predictions:
    • Current data, including observations from telescopes like the European Space Agency's Planck telescope, suggest that the universe's expansion may continue indefinitely. Future studies aim to determine whether dark energy has remained constant or varied over time since the Big Bang.
  6. Cyclic Cosmology and Quantum-Gravity Speculations:
    • The Big Crunch aligns with cyclic cosmology and recent quantum-gravity theories, proposing a cyclical pattern of universal expansion and contraction originating from a gravitational singularity.
  7. Critical Density and Omega Value:
    • Calculations suggest that if the universe's density surpasses a critical value (Omega), known as critical density, a collapse becomes highly probable. A value of Omega greater than 1 indicates sufficient matter density for an eventual Big Crunch.
  8. Observational Evidence:
    • Astronomers observe the universe's expansion by studying distant galaxies moving away from each other, supported by evidence like cosmic microwave background radiation, remnants of the Big Bang, and the formation of cosmic structures.
  9. Formation of Cosmic Structures:
    • Over time, structures of dark matter form, laying the groundwork for the creation of stars, planets, galaxies, and the emergence of life within the universe.

Because the Big Crunch is really the result of the Big Bang, we will start there. Astrophysicists have long considered that the likeliest conclusion is the Big Bangs reverse - the Big Crunch. Paul Davies considered one scenario, whereby the Big Crunch occurs some 100 billion years from now.

The Big Crunch scenario posits that the density of matter across the Universe is so great that gravitational attraction would outweigh the Big Bangs cosmic expansion. In a Big Crunch scenario, the expansion will eventually stop, and then reverse, and galaxies would grow ever closer. In this scenario, current universe expansion eventually slowed, stopped, then reversed, starting contraction.

Then, because gravity is pulling the matter, the universe begins contracting, falling inwards, until the universe has collapsed again, becoming a superhot, super-dense singularity. Everything in the universe will have collapsed to a tiny dot, just as it began. Eventually, space may either collapse on itself, wiping out every star and galaxy that exists, or it may expand outwards, into what is basically an infinite vacuum.

Dark matter and ordinary matter -- objects such as planets, galaxies, and stars -- are pulled toward one another by gravity. Dark energy is the name given to an unexplained force which works against gravity, pulling the universe apart at its seams. If dark energy speeds up expansion even faster than is currently expected, a big crack is coming.

Current data from the European Space Agencys Planck telescope and elsewhere are consistent with such an expansion continuing indefinitely. In the next decade or so, scientists should be able to say with much greater certainty if dark energy has been constant, or has changed, in the 14 billion years since the Big Bang. Proponents of the "Big Bang" theory think that dark energy would overwhelm dark matters strength and prevent the Big Crunch.

According to a study by Andrei-Ijjas-Steinhardt, this scenario fits naturally cyclic cosmology as well as recent quantum-gravity speculations. Basically, a big bang means all the matter created in the Universe is pulled back to the gravitational singularity it originally came from. The theory of The Big Bang Singularity proposes the onset of the Universe at a single point in space-time, having an infinite amount of density and energy (Tereza Pultarova, 2017).

Calculations made recently have given the idea that the universe could be less dense than a critical density. It is thought that if density is greater than a specific value, known as critical density, then an eventual collapse is very likely. If Omega(o) is greater than 1, that is, the space is filled with sufficient matter, a big crash is inevitable at some point.

Outside of our own space neighborhood, each galaxie is squeezing out farther away than we are; an obvious indication of expansion. By studying the old lights, astronomers can see what is called the Big Bangs so-called relic radiation, otherwise known as cosmic microwave background. Then, structures of dark matter formed, and building blocks for stars, planets, life, and galaxies were assembled.

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