In the Movie:
The Big Crunch is expected to happen in 2092 - in Mr. Nobody that is. When it does occur, time reverses and it is implied that Nemo lives his life all over again, but backwards. Is this a real possibility for the universe?
the theory:
If the Big Bang theory is true, then the universe is constantly expanding. But, what will happen if the universe stops expanding? Scientists have speculated that if/when this happens, the universe will retract and collapse on itself.
There are certain properties of the universe that scientists have to determine first to see if this is a real possibility. One of those properties is the density. It is believed that if the density is higher than a certain value, also known as the critical value, an eventual collapse is highly probable.
At first, scientists believed there were two main factors that really influence the expansion of the universe: the gravitational force of attraction between all the galaxies (which is proportional to the density) and their outward momentum due to the Big Bang. Also, Newton's Third Law states that for every action there is an equal and opposite reaction, so this could apply to the expanding universe; after it finishes expanding, it will need to contract back. But, scientists have found that the universe is actually expanding at regions farthest from us, disproving The Big Crunch Theory.
This can be explained by applying what scientist have found called "dark energy." This force is highly believed to be pushing all of the galaxies farther and farther apart. NASA's Chandra X-ray observatory has measured that the dark energy strength is constant. With this constant dark energy strength, an ever-expanding universe is the most likely scenario. This being said, The Big Crunch Theory is not very likely, but an interesting theory to think about.
There are certain properties of the universe that scientists have to determine first to see if this is a real possibility. One of those properties is the density. It is believed that if the density is higher than a certain value, also known as the critical value, an eventual collapse is highly probable.
At first, scientists believed there were two main factors that really influence the expansion of the universe: the gravitational force of attraction between all the galaxies (which is proportional to the density) and their outward momentum due to the Big Bang. Also, Newton's Third Law states that for every action there is an equal and opposite reaction, so this could apply to the expanding universe; after it finishes expanding, it will need to contract back. But, scientists have found that the universe is actually expanding at regions farthest from us, disproving The Big Crunch Theory.
This can be explained by applying what scientist have found called "dark energy." This force is highly believed to be pushing all of the galaxies farther and farther apart. NASA's Chandra X-ray observatory has measured that the dark energy strength is constant. With this constant dark energy strength, an ever-expanding universe is the most likely scenario. This being said, The Big Crunch Theory is not very likely, but an interesting theory to think about.