Well, there is no definitive answer to this, since it is a matter of opinion, but in my opinion he is on top as far as mathematical genius. He made a tremendous amount of strides in mathematics, physics, and most of the rest of topics similar. He also had some deep thoughts.
Hey, thanks for asking. 🙂
In one sense he was not a scientist, although his work is so important to theoretical physics. His proofs are mathematical proofs and are not based on any scientific experimental data.
It is almost inconceivable to imagine what went on in his mind and his ability to focus on physical problems and work out a solution and predictions mean that he is a true genius.
Given the time era that he lived, studied, taught and pioneered the direction of physics, which lead to further studies and other great scientists. Albert Einstein was a fantastically intelligent man. His breakthrough work is equal to inventing the wheel when a wheel didn’t exist. Scientists today improve on that wheel. The only other scientist/inventor that I can honestly say is equal to Albert Einstein is, Leonardo Da vinci.
Leonardo De vinci is literally responsible for nearly everything that we do in the industrialized world, including the mechanism that operates the gates through the Panama Canal. It is from many of Leonardo De vinci’s inventions, drawings and theories that science leaped ahead as far, fast and accurately as it has since Leonardo’s time.
Albert Einstein was equally as bright during his own time.
Aside from those two, Carl Sagan is likely the next brightest intelligent man that has ever lived so far in current time, although sadly, he recently passed away from cancer.
The only one left, now, intelligent enough to be up there with all of those whom I have mentioned would have to be, Steven Hawking, who is nearly dead from Lou Gehrig’s disease.
Perhaps Einstein was the greatest synthesist of mathematical physics during the last four-hundred years or so. He was able to provide deep insight into problems and then collect together mathematical ideas and partially formed theories to provide ground breaking and often novel solutions to problems. Most people recognise him as the greatest scientist of all time, although Newton must also rank along side of him .
I have read somewhere that his unfinished work(s) have found new light in many modern approaches to fundamental physics and cosmology. Ironically, his ‘greatest blunder’ (his own words) the cosmological constant keeps reemerging in cosmological calculations and observations!