Poor man's copyright. How to prove that you had the idea first?

Scenario:

You made a scientific discovery and you want to prove that you were the first who made it. Your publication is months (or years) away. What to do?


Solution:

Send yourself a certified letter containing the details of your discovery and do not open it. This way the date of your contribution is certified by the Federal Government and in the future dispute over rights of scientific discovery (or copyright), you have a proof of it. Reportedly, this is the method Hollywood screenplay writers use as so-called "poor man's copyrights."

Does anybody know if this holds in court?


Update:

It looks like the "poor man's copyright" concept does not work. References are provided in the comments below. On of the great things about blogging is the self-correction: if your write something incorrect, somebody will point it out. Thank you.


Idea by: Navin Kedia, DO (publication permitted)
Image source: OpenClipArt.com (public domain)