[Diogo_Afonso_Leitao (OP)]

I have got an idea about the Universe and having this answer would be a great help for me to work on my thesis.

Sorry for grammar errors, I am only 13 and english is not my native language.
Thank you,
Diogo.

[Diogo_Afonso_Leitao (OP)]

As far as I know, the collision of two particles results on nuclear fusion. So my question is: Theoretically, a collision of two particles with so much energy and speed could cause the atoms to break up and cause nuclear fission instead of fusion?

[chiralSPO]

The collision of two nuclei can certainly result in fission of one or both of the nuclei. However, the nuclei must be large enough and unstable enough to undergo fission.

For instance, it is impossible for a hydrogen nucleus to undergo nuclear fission (there is only one proton). And while nuclei like that of ¹²C could hypothetically break into smaller pieces, this is highly unlikely because ¹²C is so stable.

Realistically only nuclei heavier than iron are likely to undergo any type of fission event, and you still need a lot of energy. If your theory is about the early universe, you might want to rethink the importance of fission, because in the beginning there was really only hydrogen and helium. It is only through the action of stars and supernovae (over billions of years) that we have any heavier elements at all.

[Diogo_Afonso_Leitao (OP)]

The collision of two nuclei can certainly result in fission of one or both of the nuclei. However, the nuclei must be large enough and unstable enough to undergo fission.

For instance, it is impossible for a hydrogen nucleus to undergo nuclear fission (there is only one proton). And while nuclei like that of ¹²C could hypothetically break into smaller pieces, this is highly unlikely because ¹²C is so stable.

Realistically only nuclei heavier than iron are likely to undergo any type of fission event, and you still need a lot of energy. If your theory is about the early universe, you might want to rethink the importance of fission, because in the beginning there was really only hydrogen and helium. It is only through the action of stars and supernovae (over billions of years) that we have any heavier elements at all.

Thank you very much for your help! I posted my idea on the new theories section

[evan_au]

In the commercially important case of Uranium fission, the collision of a neutron with a Uranium 235 nucleus is sufficient to cause it to fission.

Uranium 235 has a large and unstable nucleus. It will decay all by itself (in about 700 Million years, on average), with no outside assistance.
But if it absorbs a neutron, it is transformed into an even more unstable nucleus, which will fission immediately.

See: http://en.wikipedia.org/wiki/Nuclear_fission

There are research groups around the world competing with each other to produce larger and larger elements on the periodic table.

They do this by smashing together moderately large nuclei, forming an incredibly unstable large nucleus, which immediately fissions.
See: http://en.wikipedia.org/wiki/Transuranium_element#Super-heavy_elements