What makes a hero? Dying used to be a prerequisite - but these days a good right foot is enough. Over five pages, we ask who makes the grade

Einstein is the object of John Rigden's admiration for his determination to apply reason to the toughest challenges

A US sports commentator recently asserted that a particular player was very smart. To emphasise his claim, the commentator said: "He's no Norman Einstein, but..." Everyone knew he meant to say "Albert" because Albert Einstein is the standard for intelligence. But there are a lot of demonstrably smart people. What makes Einstein the standard? The man himself suggested an approach to an answer: "The essential in... a man of my type lies precisely in what he thinks and how he thinks..." Einstein's greatness is certainly rooted in the what and how, but the fact that he was a physicist allowed him not only to come up with great theories but to demonstrate the power of his mind in a way that was awesome and compelling.

Einstein had a long career, but what he did in 1905 was breathtaking. In six months, Einstein wrote five papers, all fundamental papers and all very different. Today, 100 years later, these five papers stand as landmark contributions to science. His 1905 tour de force started in March with him at his most controversial. On March 16, Einstein sent a paper to the editor of Annalen der Physik in which he made the audacious assertion that light consisted of discrete, individual, localised particles. This assertion contradicted 100 years of experimental evidence that demonstrated that light was a continuous wave. In fact, the March paper was the only 1905 paper that Einstein himself called "revolutionary". Indeed, it was so revolutionary that 17 years passed before Arthur H. Compton's 1922 X-ray scattering experiment forced physicists to accept it, although the renowned scientist Niels Bohr rejected it until mid-1925. Today, Einstein's light particle, christened the photon in 1926, is a cornerstone of physics.

ÖйúAƬ

Einstein's April paper was his dissertation; two earlier dissertations had been rejected. It concerned the dimensions of molecules in a liquid. In 1905, the existence of atoms was still being debated. Einstein's dissertation provided additional evidence, albeit indirect, that atoms really exist. The paper has many practical applications and is one of his most cited.

In addition, it set the scene for his famous May paper, completed just ten days after he finished his dissertation. It concerned Brownian motion, the observation that pollen particles suspended in water move randomly, along a zigzag path. Einstein showed that water molecules could momentarily form a compact bunch of molecules that could bang into a "giant" pollen particle and exert enough oomph to push a particle ahead. These molecular convoys strike the spherical pollen particle at random times from random directions, leading to the zigzag motion. The magic of this paper is in the way Einstein expressed his final result: with just a ruler and a stopwatch, Einstein's theory of Brownian motion could be tested and, in the process, confirm the reality of atoms. It was the May paper that finally turned atomic sceptics into atomic believers.

ÖйúAƬ

Einstein's June paper on the special theory of relativity restructured the two most basic concepts of physics: space and time. He began with two seemingly innocuous axioms: the laws of physics and the speed of light are the same for all observers. From these hypotheses came stunning consequences, including deliberations about the relative natures of length and time. Another consequence was the subject of Einstein's fifth and final paper of 1905, published in September. It introduced the world to its most famous equation: E=mc2. It is hard to believe that matter and energy are the same thing, but Einstein showed that nature exchanges mass and energy back and forth indiscriminately and makes no distinction between them. The special theory of relativity is now a super theory that sits in judgement over all other physical theories that must be consistent with it.

Einstein once said: "I want to know how God created this world... I want to know His thoughts, the rest are details." This statement reveals a lot about how Einstein did his physics: he avoided the mundane and he eschewed trivialities, focusing instead on fundamental principles and extracting unexpected insights. Einstein was troubled, for example, by the contradictory natures of continuity and discontinuity. Continuous waves interacting together offered no problems; likewise, discontinuous atoms interacting together were unproblematic. When continuous waves encountered discontinuous atoms, however, Einstein, alone among physicists, saw grave problems; and it was this issue that led to the light quantum theory published in his March paper.

During his great breakthroughs of 1905, Einstein worked outside the physics community as a patent clerk in Basel, Switzerland. Throughout his career, he rarely had co-authors. "I am a horse for single harness," he said. He worked alone in the solitude of his own mind as he sought "God's thoughts" using the power of human reason. All his theories were products of reason, but he always connected his abstract ideas to an experiment that could verify them.

In 1916, his single greatest paper, The Foundation of the General Theory of Relativity , was published and showed how mass shapes the space around it and how, in turn, space shepherds the motion of mass. This meant, for example, that light particles would have their path altered as they passed by a massive object. From this theory, Einstein predicted that the path of light passing close to the Sun is deviated by a very specific angle. In 1919, physicist Arthur Eddington experimentally measured the deviation of starlight as it passed the Sun during a total eclipse and found that his result agreed with Einstein's prediction.

When a theoretical prediction touches on one of humankind's big questions, such as the nature of space, and when an experiment confirms that prediction, the result is high drama. Einstein became an international icon after Eddington's experiment because physics allowed his intellectual powers to be demonstrated so that everyone could admire them.

ÖйúAƬ

As such, he is a worthy model for all students, but especially for physics students. He once told a student: "One should not pursue goals that are easily achieved. One must develop an instinct for what one can just barely achieve through one's greatest efforts." This is advice that everyone can follow. To seek how the world works is a challenge that becomes more satisfying the more you learn. Einstein never went to bed bored and never dreaded the dawn of a new day. Although he had the singular ability to recognise the most fundamental questions and to find solutions to them, it doesn't matter where on the scale of intelligence you stand. Whatever one's intellectual abilities, the challenge of capturing a glimpse of an unknown facet of nature is enticing and the satisfaction it brings has few equals.

John Rigden is adjunct professor of physics at Washington University in St Louis. His book Einstein 1905: The Standard of Greatness is published by Harvard University Press, ?11.49.

WHO INSPIRES YOU?
Kathy Sykes, 37, the youngest professor of public engagement in science and engineering, Bristol University, and co-director of the Cheltenham Festival of Science.

ÖйúAƬ

"My mentor was Sue Pringle, who worked in the School of Continuing Education at Bristol trying to get people interested in chemistry. I was doing a PhD in physics at Bristol and saw her communicating with a group of school kids. I thought: 'I want that job.'

"I had been hungry to find something to do that I really believed in. I saw Sue doing this stuff and thought this would combine science and passion for communicating with human beings because I don't just enjoy science but issues around science.

"I got to know her and said: 'I want your job' and she was remarkably generous. She gave me good advice.

"Then, when she couldn't do a talk to a Women's Institute, I did it and afterwards she bought me a huge bunch of flowers. Then she was just there to give me support. She said: 'You may think you want my job but there are other things that are more fun.'

ÖйúAƬ

"Mentoring is incredibly powerful, especially in fields where you feel a bit lonely, such as a woman in a physics department, although it might feel a bit different if there were more women around. What you want is people around who understand the kind of things you are going through and are ready to talk about personal issues as well as work. The most valuable thing is finding someone who you have enormous respect for who sees that you have potential."