Question

Where can I submit my new theory in Physics?

Answer 1

I think one of the route is to become member of American Physical Society and submit your work for publication.

You can check for similar Society in your Country of Residence.

Best

Answer 2

Realistically it is unlikely.

Explanation:

If you are at University then there is a clear path (submit it to one of the many journals for peer review and eventual publication.) Effectively, the academic community criticise (in the technical, not personal sense) your idea prior to it being made public. Many people (Einstein included) have found the system sufficiently unwieldy (effectively closed to outsiders) that they have published in lesser journals initially. Perhaps a letter to New Scientist (or similar popular magazine) might be a better starting point?

There are also a number of websites where you can post bright ideas that might be of use to someone else, but you gain no profit from them.