Scientists are about to celebrate Einstein Year. But why, asks Roger Highfield, do we still remember the shaggy old unproductive Einstein?

Everyone thinks they know Albert Einstein. He's the eccentric boffin who gave the world a new theory of gravity and the pacifist who supposedly invented the bomb - then tried to have it banned.

Slow start: 'Einstein graduated from the Swiss Federal Polytechnic with good - not great - grades. Attempts to become a physics assistant came to nothing'

He is that mad scientist in Princeton with electrified hair, the little professor who shuffles around sockless in moth-eaten sweaters, puffing his pipe. Often he sticks his tongue out. He still stares out of T shirts and posters.

Erase the prevailing image of Einstein as Walter Matthau with a cosmic aureole. Forget Princeton. This is not the creative Einstein but a faded and distorted version of the original.

Next year, thanks to the detective work of scholars, we can at last see the real Einstein as scientists pay tribute to the 100th anniversary of the intellectual flowering of the world's first superstar scientist.

The year of 1905 is when the 26-year-old laid the foundations of modern theory that ranges from the smallest scale - quantum theory - to the largest - relativity - and helped to redraw our understanding of the nature of energy, matter, motion, time and space. The astonishing creative explosion marked the start of a remarkable two-decade run at the cutting edge of physics.

Five years before his annus mirabilis, Einstein graduated from the Swiss Federal Polytechnic in Zurich with good - not great - grades. His attempts to become a physics assistant came to nothing - his professors thought him confrontational. He had begged for jobs in Vienna, Leipzig, Göttingen, Stuttgart, Bologna and Pisa.

Thanks to an old friend, he managed to get a provisional job offer at the Patent Office in Berne. But this move would cast a long shadow: he and his first wife, Mileva, had to give up their first - illegitimate - child. Einstein had not even set eyes on his daughter Lieserl. But he feared that scandal would end his first career opportunity, as a probationary technical expert, "third class". Even today, we don't know Lieserl's fate.

Berne in 1905 was a relatively small town of 60,000 inhabitants. None the less, it was the capital of the Swiss Confederation and an intellectual powerhouse, being the seat of the International Postal Union, International Telegraphic Union, International Office of Railway Transports and the Convention de Paris, an intellectual property organisation. And, of course, there was the Patent Office.

Some claim that what Einstein called his "cobbler's job" was the key to his astonishing intellectual outburst. By one view, the need to conjure up an invention in his mind's eye helped hone his creativity. By another, Einstein was inspired by a stream of patents on timekeeping: the age of the telegraph and the steam train meant that the co-ordination of the Zytglogge (clock tower) at the end of his road with clocks in other towns was important. This was the issue that Einstein had puzzled over in thought experiments about the nature of time.

Robert Schulmann, former head of the Einstein Papers Project, believes that the Patent Office provided Einstein with a "tactical retreat" so he could pursue a long-term plan he had hatched with his former tutor, Alfred Kleiner, the only physics professor at the University of Zurich.

Einstein thought that Kleiner was an idiot. But Kleiner was smart enough to understand that this wunderkind would go nowhere because his science crossed intellectual boundaries. Unlike Germany, where Einstein's first love -theoretical physics - had thrived for a decade, the Swiss placed more emphasis on old-fashioned experiment.

Kleiner would set in motion an effort to create a professorial chair tailored to Einstein's talents. This marked an astonishing act of faith in his ungrateful protégé and marks out Kleiner as perhaps the first physicist to recognise Einstein's genius.

Mileva, however, would give him crucial emotional support during his darkest days, obtain books and check his work. His love letters to "Dollie" fizz with scientific ideas. Yet it is important not to overstate her contribution.

Their rented flat on the second floor of 49 Kramgasse - now a museum - was a forum for others who played a role in honing his ideas. His old friend Michel Besso, whom Einstein mocked as an "awful schlemiel", had a talent for asking childlike questions that were deceptively tough and, if answered, very revealing.

Years later, he referred to approaching Besso to discuss his misgivings about an apparently unchanging speed of light, a foundation stone of relativity. In their discussions, often during the stroll between the Patent Office and Kramgasse, "I could suddenly comprehend the matter." After a year of fruitless puzzling, the breakthrough came while talking to Besso.

He would discuss ideas with his "students" in Berne, Conrad Habicht and Maurice Solovine. The three constituted themselves with mock formality as the Olympia Academy.

When describing his 1905 papers to Habicht, Einstein called the first "very revolutionary". It was sent to the journal Annalen der Physik on March17, three days after his 26th birthday. It offered an explanation of the photoelectric effect, which Einstein had written about rapturously to Mileva after she discovered that she was pregnant.

Experiments had shown that electrons were ejected from metal surfaces when the surfaces were struck by light. But science could not explain why the speed with which the electrons emerged varied with the colour rather than the intensity of the light. Einstein suggested that light beams consisted of microscopic particles, which he called light quanta. As the brightness of the light increased, more quanta rained on the metal and more electrons were blasted out. But the speed with which they emerged increased only when the quanta grew bigger, as the light moved to from the red to the blue end of the spectrum.

Einstein was returning in part to Newton's idea of light as a stream of particles, long since dropped because waves were better at explaining such effects as interference and diffraction. Yet even as Einstein talked of light quanta - or photons, as they were later called - he also referred to light as having a frequency, an essential part of wave theory. He was confronting what has become a famous paradox: light has the properties of waves and particles. His explanation of the photoelectric effect won a belated Nobel prize in 1922.

The next great paper was received by Annalen on May 11. Its subject was Brownian motion, named after the Scottish naturalist Robert Brown. As early as 1827, Brown had used a microscope to observe the random zigzag motion in water by tiny particles such as pollen grain fragments. But he was puzzled by its cause. Einstein gave the answer: the particles were buffeted by invisible molecules. At that time, some physicists still doubted the physical reality of atoms.

Einstein's greatest paper, "special relativity", was received on June 30. In essence, his aim was to reconcile Newton's laws of motion with the theory of electromagnetism produced by the Scotsman James Clerk Maxwell in the 1870s. Travel at light speed is allowed by Newton's laws but wreaks unfortunate consequences on Maxwell's picture of light. If we regard a light beam as a series of peaks and troughs then we can see that an observer moving alongside with the same speed would be tied to a particular trough or peak and would no longer "see" the oscillation. In other words, the beam would no longer exist to someone travelling with it. There was a deeper problem. According to Newton's laws, there is no such thing as absolute motion. If you measure the speed of a car, it could be relative to the ground, relative to the Moon, or relative to some distant galaxy. At first sight this is inconsistent with Maxwell's prescription of an absolute value for the speed of light (186,000 miles per second). What Einstein did was to accept both apparently contradictory principles. In order to keep the speed of light constant - irrespective of the speed of the observer relative to the source of the light - Einstein had to distort time and distance, predicting head-reeling effects: he predicted that a moving clock would appear to tick more slowly than one at rest.

	Enduring image: a hundred years on and the world's first superstar scientist will be paid tribute

In September, Einstein submitted another short article on the relationship between mass and energy: when a body releases energy in the form of radiation its mass decreases by a proportionate amount. But its true importance did not become clear until two years later, when Einstein announced that the reverse was also true: that all mass has energy. The formula with which he captured this relationship, E = mc 2 (in which E stands for energy, m for mass and c for the speed of light), is the most famous of all. If c is expressed in metres per second, c2 is a huge number: a nine followed by 16 zeros. In other words, a vast amount of energy can be extracted from a tiny amount of mass - such as the loss in mass that occurs when the nuclei of heavy elements such as plutonium fall apart. Einstein called this the most important consequence of his relativity theory, and the atom bomb was to provide the most dramatic vindication -though Einstein had nothing to do with its development.

Many remark on how it was almost a miracle that a serious journal like Annalen took a nonentity from the Patent Office seriously and how would not happen today. Einstein was lucky in that his first (not very impressive) papers were published and the journal had a policy of publishing subsequent work.

The 1905 papers seem to cover dazzlingly disparate subjects, but Prof Jürgen Renn of the Max-Planck-Institut für Wissenschaftsgeschichte, Berlin, says they are united by Einstein's "particulate" view of the world, understanding it in terms of atoms, molecules, electrons and tiny chunks of energy - "quanta" - which was revolutionary. In his relativity paper, where he meshed theories of movement and electromagnetism, he viewed electricity as electrons.

Many remark on Einstein's somewhat poor (relative to physicists) mathematical skills, particularly when it came to his supreme achievement in 1915 of general relativity, which extended his theory of special relativity to explain gravity. But it was Einstein's astonishing range of knowledge that was important, says Prof Renn. "Einstein's vision cut across borders and boundaries."

Einstein had wrestled with the ideas that would lead to special relativity since the age of 16, when he wondered what it would be like to ride a light beam. He designed experiments to detect the "aether" (the illusory medium that supports light waves, just as water supports the wet variety). He figured out that a particulate picture of the world was incompatible with the idea of the aether. He knew he was on to something significant. "This was fantastic learning process and he drew a lot of connections between different problems that others did not see," said Prof Renn. "The apples were ripe for picking in 1905."

Why did the elderly, unproductive Einstein leave an indelible mark on the public consciousness instead of the creative Einstein of 1905? Perhaps the main reason was the media frenzy that followed the confirmation in 1919 of his greatest theory, general relativity, which overturned Newton's picture of gravity. The idea of a German theory being backed by a British expedition to measure the bending of starlight marked an inspirational vindication of rationality after the First World War's senseless savagery. "Lights all askew in the heavens, Men of science more or less agog… Einstein theory triumphs," announced the New York Times. The legend was born.

Also: www.einstein2005.ch

28 April 2004: Did Einstein get all his sums right?