The Big Crunch is one possible scenario for the ultimate fate of the universe, where the expansion of space metrics eventually reverses and the universe accumulates, eventually leading to a cosmic-scale factor reaching zero or causing the universe's reform to begin with Big Bang other.
Recent experimental evidence suggests that the expansion of the universe is not slowed down by gravity but accelerates. However, since the nature of illicit energy postulated to encourage acceleration is unknown, a major crisis is still possible, although it is not supported by observation today.
Video Big Crunch
Overview
If the speed of the expansion of the universe does not exceed the escape velocity, then the joint gravitational attraction of all matter will eventually cause it to contract. If entropy continues to increase in the contract phase (see Ergodic hypothesis), the contraction will look very different from the time of reversal of expansion. When the early universe was very uniform, the contracting universe would become increasingly clumped. Eventually all the material will collapse into a black hole, which will then merge, resulting in an integrated black hole or a Big Crunch singularity.
The idea behind this theory is that the expansion of the universe is related to the energy released in the Big Bang, therefore the velocity outside matter will decrease over time due to gravity (mutual attraction). It will act as a weight and will eventually stop the expansion. When matter is interesting and there is no problem beyond the maximum expansion point, eventually all the material will start moving in again, accelerating over time.
The exact details of events that will occur before the final collapse depend on the length of the expansion phase and the previous phase of contraction; the longer the two progress, the more events that are expected to occur in the ever-expanding universe will occur; Nevertheless it is expected that the contraction phase will not be immediately noticed by hypothetical observers because of the delay caused by the speed of light, that the temperature of the cosmic microwave background will rise during symmetrical contraction compared to the previous expansion phase, and that events that occur during the Big Bang will occur in the opposite order. For a contract universe similar to our compositions, it is expected that superclusters will join between them followed by galaxies and galaxies later. When stars are so close together that collisions between them occur frequently, the temperature of the cosmic microwave background will increase so much that stars will not be able to dissipate their internal heat, slowly cooking until they explode. , leaving a heterogeneous, heated gas whose atoms will break down into subatomic particles of their constituents because of the rising temperatures, which will be absorbed by the unified black hole before the Big Crunch itself.
Hubble's constant measures current expansion status in the universe, and the force of gravity depends on the density and pressure of matter in the universe, or in other words, the critical density of the universe. If the density of the universe is greater than the critical density, then the force of gravity will stop the universe expanding and the universe will collapse again by itself - assuming that there is no repulsive force like cosmological constants. Conversely, if the density of the universe is less than the critical density, the universe will continue to expand and the pull of gravity will not be enough to stop the universe from spreading. This scenario will lead to the death of the heat of the universe, where the universe reaches the maximum state of entropy ie thermodynamic equilibrium. In a state of thermodynamic equilibrium energy in the universe is evenly distributed so that heat transfer or other energy transfer is impossible so that no reaction that can occur in the universe as such makes it "dead". One theory suggests that the universe could collapse to the state in which it begins and then start another Big Bang, so in this way the universe will last forever, but will pass through the expansion phase (Big Bang) and contraction (Big Crunch). Another scenario produces a flat universe that occurs when the critical density is right. Under these circumstances the universe will always slow down, and eventually stop for an eternity. Although, it is now understood that the critical density has been measured and determined to be a flat universe.
Recent experimental evidence (ie observation of distant supernova as standard candlestick, and well-resolved cosmic microwave mapping) has led to speculation that the expansion of the universe is not slowed down by gravity but accelerates. However, since the nature of dark energy argued to promote acceleration is unknown, it is still possible (though not observationalally supported today) that may ultimately reverse the course of its development and lead to collapse.
Maps Big Crunch
See also
- Space portal
References
Source of the article : Wikipedia
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