Who knew? Try Einstein.

At the dawn of the 20th century, a curly-haired, 26-year-old Swiss physicist with nothing but pen, paper, and a big imagination shook up the world. In the 21st century, it's still shaking.

In 1905, Albert Einstein's annus mirabilis ("miraculous year"), he published three of the four major papers that would lead him to be characterized, arguably, as the greatest scientific mind ever.

Blown away would be big patches of Newtonian physics, with its seemingly undeniable truths that were as apparent as, well, an apple bopping you on the head. Einstein's logic was provable, too, as later experiments would show, but also counterintuitive. The universe, he showed us, was a stranger neighborhood than we had thought.

Einstein, who died in 1955, may have been Time magazine's Person of the 20th Century (sorry, Winston Churchill), but to Einstein scholars he's just as relevant today. His work has led to the search for "the scientific underpinnings of 'Star Trek,' the technologies of the 22nd century," says Michael Shara, an astrophysicist and the curator of a major new Einstein exhibition opening Friday at the American Museum of Natural History in New York.

His search for a "grand unified theory," a "theory of everything" that in the 1940s and '50s made him the self-proclaimed "village idiot" of Princeton University, is now the accepted holy grail being sought by modern physicists.

As a persona, an icon, Einstein remains one of the most familiar presences on the face of the earth, a celebrity personality as well known as Mickey Mouse or Marilyn Monroe. He's been portrayed in movies by actors from Walter Matthau to Robert Downey Jr. He's been seen on TV's "Star Trek" playing cards with present-day physicist Stephen Hawking and on stage sparring with Pablo Picasso in Steve Martin's play "Picasso at the Lapin Agile." His E=mc2 is the world's most famous (if inscrutable) equation, the basis for both nuclear power and nuclear bombs.

Amazon.com lists 248 books for sale with his name in their titles, and the Google Internet search engine links his name to 641,000 sites on the Web. His portrait (often in a lab coat and on the world's worst bad-hair day) can be seen selling products from books to cameras to computers.

Yet how he came to his remarkable conclusions about the nature of time and space remains elusive.

"When the blind beetle crawls over the surface of the globe, he doesn't realize that the track he has covered is curved," Einstein once said, trying to explain his unorthodox conclusions. "I was lucky enough to have spotted it."

"It is nearly impossible for me to comprehend how the human mind came up with something so subtle as Einstein's special relativity paper. But he did!" admires David Ward, a professor of philosophy at Widener University in Chester, Pa.

Einstein thought of himself as asking questions only children ask. He had "this simplifying way of looking at the world, and taking the risk that he might be wrong," says Gerald Holton, a Harvard University physicist who organized Einstein's papers into an archive after his death and has studied him for nearly five decades since. Rather than look for complexity, Einstein sought coherence and simplicity, a view of the big picture. "That is really running through his physics and everything else he did," Dr. Holton says. "I have not found that in any other of the many scientists I've studied."

Probing the nature of Einstein's genius is likely to continue during this centennial period, along with new tests of his theories. Atomic clocks will be sent to the International Space Station in the next few years, for example, to see if Einstein's Special Theory of Relativity holds up in that environment. "It's one of the most fundamental assumptions that's built into most physical theories, so a violation of it would be a very major thing, a very big deal," says Charles Lane, a physicist at Berry College in Mount Berry, Ga., who is helping to design the experiments.

In the past decade, Einstein's image as a genial Germanic grandfather has suffered, and his personal life will no doubt get more scrutiny. He was accused of mistreating his family, particularly his daughter, Professor Ward says. "Feminists have a justifiable beef with him about his treatment of women in general. That's certainly hurt the reputation a bit."

At the same time, Einstein used his fame to promote social causes. He was a pacifist and socialist who saw a single world government as the antidote to war. "His politics now seem kind of naive," Ward says. "More naive than just idealistic.... The world is a great deal more complicated place than that.

"We forgive him all that because he is such a wise man and a gentle man. But I don't think we look to Einstein for political insights these days."

Overwhelmingly, though, Einstein's image is still positive. People all over the world who know little about him, and even less about his work, somehow still connect with him, says physicist Holton. "They have a feeling that this person is somehow in touch with the way the world should be at its best."

For 15 years, motivational speaker Arden Bercovitz of Vista, Calif., has portrayed Einstein in front of student, business, and technical groups. "Einstein said, 'The most incomprehensible thing about the universe is that it is comprehensible,' " says Dr. Bercovitz. "That is a very hopeful, optimistic statement" in a modern world of great uncertainty.

Bercovitz uses his Einstein character to make points with his audiences about creativity and finding fresh ways of solving problems. Einstein's definition of creativity, he says, is "seeing what everyone sees - and thinking what no one has ever thought." Einstein liked to think in pictures rather than words. "This is a very powerful method of thinking," Bercovitz says. "It lets us go beyond our vocabulary into new areas of thought."

Hanoch Gutfreund, a theoretical physicist and former president of the Hebrew University of Jerusalem, which is lending important Einstein documents from its archives for the New York exhibition, has high hopes it will bring out the impact Einstein had on science, on the culture of science, and on present-day technology better than ever before. Dr. Gutfreund says he believes each of Einstein's three 1905 papers was worthy of a Nobel Prize (which Einstein finally won in 1921), as was his general theory of relativity, published in 1916.

"His work on Brownian motion gave rise to statistical mechanics," Gutfreund says. "His work on the explanation of the photoelectric effect is one of the bases of quantum theory. His work on special relativity is proved beyond any doubt and reflected in many branches of physics.

"And maybe the most sophisticated intellectual achievement, his general theory of relativity - which has revolutionized the Newtonian picture of space, matter, and gravitation - has been the basis of the present theories of the universe, cosmology, [and] the black-hole phenomenon. All these stand as the pillars of modern science."

The calculations in the special relativity paper, Holton says, aren't what is impressive - "there's hardly any mathematics in it that is beyond high school now." But the implications are enormous. For Gutfreund, "teaching the special theory of relativity to young students was always the greatest thrill of my career. You begin with two very, very simple assumptions, deceivingly simple, and then ... you go through a set of logical arguments - and you get to the most far-reaching consequences."

• The exhibition 'Einstein,' the kickoff event of the Einstein centennial, opens at the American Museum of Natural History in New York Friday and runs through Aug. 10, 2003. It will travel to three other US venues (Los Angeles and most likely Boston and Chicago) before arriving in Jerusalem, home of the Einstein archives at The Hebrew University, in time for the official 2005 anniversary.