If I tell you how the universe works, how can I be sure I get credit for my theory?

The best way to guard against those thieving scientists stealing your idea is to never tell one of them about it.

Seriously, unless you are well-versed in physics and mathematics and have the proper credentials and experience with interpreting data and drawing conclusions from it, any comments or ideas you have would make no sense to an astronomer even though they might make perfect sense to you.

In cosmology we are not after ideas that sound good, we are after theories that comply with observational evidence. For thousands of years, all you had to expound was a 'good idea' and it was accorded equal weight with one that was carefully-reasoned. Today the stakes are far higher, and the standards of evidence are far more rigorous than in past centuries when all you needed was a good story and a few hundred followers to believe it.