Student or Learner
I have a book titled "Who was Albert Einstein?" I wonder why it's not "Who is Albert Einstein"? I can guess it's because he's dead, but I think it's okay to say, " Albert Einstenis the greatest scientist of all time."
Is it wrong if the title is "Who is Albert Einstein?"
"Albert Einstein is the greatest scientist of all time."
Note in particular, 'of all time'.
This sentence is stating a fact. He's greater than Aristotle, he's greater than scientists living today. We use Present tense for facts which hold true for the past, present, and (foreseeable/predictable) future. Look at two alternatives:
"Albert Einstein was the greatest scientist of all time."
"Albert Einstein will come to be regarded the greatest scientist of all time."
(1) means that somebody else has come along since Albert and is now regarded as 'greater than he/the greatest'. (2) indicates that his recogniztion as 'the greatest' may come some time in the future. Do either of these convey the same meaning as your fact expressed in the Present tense?