Big Crunch?

Question

They say one day the universe will collapse and do the exact opposite thing the Big Bang did. But how can they prove this kinda stuff?

Answer 1

First, a remark on a previous answer: A CHRISTIAN first introduced the big bang theory. And if we were all still christians of the ignorant variety, we'd still be living in the dark ages.

There are three possible 'endings' for the universe:

1) It will continue to expand forever.

2) It will collapse upon itself (Big Crunch)

3) It will expand but the expanding will get slower and slower.

It was once believed that the outcome for our universe only depended on the density of matter in the universe. Too much matter density would mean a big crunch (gravity overpowers the expansion and pulls everything back in). Too little would mean expanding forever(expansion overpowers gravity). However, there is a 'critical density' at which option 3 would be our ending (gravity balances out with the expansion). According to most measurements of the density of matter, our universe has the critical density, meaning many scientists believed that ending number 3 was the correct ending for our universe.

However, recent observations show that the universe is currently expanding faster and faster. This did not make sense with current thought. The expansion should not speed up if the expansion is the result of the big bang alone. It should be losing energy. This is why you now hear about dark energy, an energy that can't be seen but that causes the universe to expand faster and faster. So, maybe ending number 1 is the ending for our universe after all.

Another way to think about it is by trying to determine the overall shape of the universe. If it has positive curvature (like a sphere), matter will recollapse (big crunch). If it has negative curvature (like a saddle shape), it will expand forever. If it has zero curvature (flat on the large scale), it will expand but the expansion will get slower and slower.

At this point it is difficult to say how the universe will end. This whole business with dark energy will have to be resolved first. What is important is that we, as humans, continue to search for answers to our questions through observations and the scientific method.

Hope this helps.

Answer 2

The previous answer is perfectly correct. There is much debate about the nature of dark energy. It seems that if you added up all the mass/energy in the universe then 70% of it would be dark energy.
How it manifests itself with regards to time and distance is also uncertain. The more extreme theories suggest that the universe will keep expanding faster and faster. Galaxies will be ripped apart then stars then planets . Eventually even atoms until the only things left will be subatomic particles. Even mighty black holes will suffer this fate. This theory is funny enough called "The Big Rip".

Answer 3

According to complex mathematics and special equipment, astronomers can measure the distance of other galaxies from our galaxy and from each other. They have noticed that while all the galaxies they have measured seem to be moving away from one single point, apparently the movement is slowing. Therefore, based on deduction, if something slows, it most likely is going to eventually be pulled back to its original point of origin.

A bad analogy would be a slowing car because when it stops, it most likely will sit where it is when on flat ground. A better example would be a ball thrown into the air. It originated from the Earth and the gravity eventually pulls it back. Before it stops and returns, it does slow down like some galaxies are doing.

Answer 4

They can't prove it. It's a theory. There's alot of things that you can't prove, but are still vald scientific theories. That's how science works. There are no definate 100% answers.

Answer 5

you can't prove what you can't duplicate.

they can guess, using all kinda fancy equasions, and high sounding ideas.
but the truth is, when something is prooved, the results can be duplicated.

and there are varibles that are unknown to humans,

Answer 6

well if you are christian you wouldnt have accepted the big bang theory. therefore the "big crunch" wouldnt be true either