Is there a way on the net to search and find old acquaintances of whom you only know the first name or so?

you could use facebook by searching “networks”, if the network isn’t too large that is. You wouldn’t want to go page by page for hundreds of pages.

But as I recall, you can narrow search results by name, network, and so many other areas.

If you have sufficient supporting data, like where they work, how old they are, where they live, where they went to school etc., you might be able to narrow it down, but no chance with just a name. I successfully located a woman who I hadn’t seen for twenty-five years and who had re-married twice (hence I had no idea of her full name). I did know her first and second name and the name of her kids as well as her date of birth. That combination of data was sufficient to locate her in just a few minutes – nearly twenty thousand kilometres from where I last saw her.

Just first name. No. But yes if you have enough additional data.
DarkScribe is right on.

@ChazMaz @DarkScribe @RandomMrdan Well, thank you guys. Yes, it’s very intriguing how one can come into contact with an old acquaintance.. so far passed by that lives have changed almost completely… It has happened to me already in a few cases.. always pleasant and inspiring. I seek to find now the almost impossible to find childhood friends, classmates, etc..
wish me luck..

cheers.