Social security is not going to collapse unless the rest of the US goes first. It's no more an "obvious truth" than "global temperatures are going to rise 10 degrees by 2100." Yes, it could happen, but only if we do nothing policy-wise to fix it, which is unlikely.
Medicare is another story. Look at the this graph to get an idea of the difference:
It was a little tangential, and making 100-year predictions about global warming probably set off someone's troll-o-meter (wasn't me). Don't worry about 0 or -1; it's usually just a gentle reminder to be polite in these discussions.
(Note: nothing annoys people more than commenting on moderation instead of the main article.)
Medicare is another story. Look at the this graph to get an idea of the difference:
http://www.prospect.org/csnc/blogs/ezraklein_archive?month=0...
(Liberal blog, but the data speaks for itself.)