Thor Heyerdahl (Not a Jew) had an idea. What if the people of Polynesia originally came not from Asia, but from South America? What if ancient Americans built rafts that traversed the Pacific Ocean and built civilization on those remote islands? Seems possible, right?
So Heyerdahl went out to prove the possibility. He built a raft from balsa wood without using any modern technology and sailed over 4000 miles from Peru to Polynesia. A crew of five joined him on the trip; four were Norwegian, like Heyerdahl himself (no, the boat's navigator Erik Hesselberg wasn't Jewish; just another Scandinavian -berg), one was Swedish. The Kon-Tiki expedition eventually arrived at Raroia atoll after 101 days.
First of all: pretty cool, right? Heyerdahl, Hesselberg and the rest of the crew are modern-day explorers, who took on the ocean and won. (They even won an Oscar for Best Documentary for the film that documented the voyage!) But second of all: well, let's just say that they didn't exactly prove anything. Scientists today continue to believe that Polynesia was mostly settled from Asia, and while a Heyerdahl-esque trip was definitely possible, South American migration did not have a major influence on the South Pacific.
Not to be deterred, Heyerdahl tried to prove that North America could have been settled by Egyptians (there are pyramids on both sides!) and built a papyrus boat that traversed the Atlantic Ocean (on the second try). He then tried to find origins of Norse mythology in the Caucasus mountains of Azerbaijan...
Clearly, the guy had some ideas.