My boss that I worked with for a few years in the commodities sector has to be the smartest that I personally know
If I were to say who's the smartest alive today, I would have to say it's either Stephen Hawking or another astrophysicist that he is affiliated with. I mean, the kind of math & concepts involved in quantum physics & other astronomical studies just blows my mind. His book 'A Brief History In Time' really blew my mind when I read it, and it was nice cuz as complex as it can get, it's written in a very general & basic level that can be understood easily by pretty much any reader.
As for smartest ever ... It's hard to say. The men today are building off the ideas, concepts, & results of studies of histories previous smartest men, and therefore have a big headstart over any of the other men who helped discover the core of where we are today in techonology and whatnot. I say this, because I still believe Stephen Hawking could go down as one of the smartest men to ever live and the Einstein of our day, but again, this is a man who studied Einstein as a kid to this day, so in a way Einstein is living within him knowledge-wise, and should deserve credit as possibly being the smartest man ever consider the current day & resources available to him at the time.
Good question to ask! I like it