Week 1 Day 1 Einstein

THE CENTRAL FACTS FROM THE COURSES YOU ALWAYS MEANT TO TAKE, IN 25 LECTURES; A final examination will be set at the end of term. All graduates will be awarded a diploma and the ten best results will receive a year's subscriptio n to the Independent

The story goes that Einstein was at a dinner party in Princeton in the late 1940s when one faculty member dared to address the great man. When I get my good ideas, he said, I jot them down in a little notebook so I don't forget them. What do you do? And Einstein replied, Ah, it's so rare that I get a good idea ...

Everyone laughed, but by this point it was true. He had popular esteem, but it was now years since his main contributions had been made, and the new generation of physicists disregarded him.

It had been so different before. His happiest times had been in the first years of this century, long before fame, when he was just a new university graduate in his early twenties, living with friends in Switzerland, then married to a bright female student. He was earning enough money from an easy civil service job to spend his evenings and weekends in pub visits, or long walks, or, above all, in having the time to think.

From his early work came the special theory of relativity, published when he was 26, which looks among other matters at the way a fast particle or spaceship will appear to get distorted in shape as an outside observer watches it speeding along. Under normal conditions, a spaceship just needs to apply more thrust energy to go faster. But if it is already at very high speeds, then a curious effect takes over: the velocity can't go much higher than it is already, yet the energy being poured in can't just go away. What happens? The energy poured in ends up augmenting the solid mass of the spaceship itself.

This should sound suspiciously familiar. The mass growth is pretty small at first, just a tiny fraction of the energy poured in - what you get by dividing the energy by c2, where c2 is the square of the speed of light. Swivel that equation around and you get the more familiar form, that energy equals mass times c2, or e = mc2.

Physicists liked this, for it explained how a radioactive clump, losing only tiny amounts of mass, could spatter out dense sprays of energy for years. But there was no wider attention until, in a series of papers beginning in 1915, Einstein went much deeper.

His attention now was on the very fabric of space, and how it is affected by the size or energy of objects at any one location in it. The conclusion he came up with was as simple as possible: the more matter or energy there is at any one spot, the more that space and time are curved tight around it. A tetchy little object, such as our Earth, only bends the space around it a little bit; the more macho Sun tugs the underlying fabric around it far more tautly.

It seems a preposterous view - how can seemingly empty space be warped? But in 1919, an English physicist led a team off the west coast of Africa, where a solar eclipse allowed the scientists, briefly, actually to see distant starlight being swivelled around the sun. It was like watching a bank shot in billiards suddenly take place in the sky overhead, where nobody had ever suspected a curved corner pocket to reside.

With the First World War just ended, this was wondrous. God may have seemed lost after the trenches, but now order had been divined in the cosmos. Even better, a German and an Englishman working together had found it. Einstein, instantly, was the greatest media celebrity on the planet.

He took it calmly, saying that because his prediction had been proven true the Germans were calling him a German, and the French were proclaiming him a citizen of the world; but if his prediction had been shown false, the French would have called him a German, and the Germans would have called him a Jew. In fact he got it wrong: his astronomical prediction stayed true, but with the rise of Hitler the Germans still called him a Jew. He left the Continent, and tried England, but Oxford did not take favourably to Jews then, certainly not ones who saw no reason to respect the class system, and he ended up in Princeton.

How unique was his work? Researchers in France and the Netherlands were getting close to his special theory, and would have caught up soon. It was his second theory, concerning gravity, which was more individual, as no one else was even close to handling that vision of object-curved space. But even this would probably have been reached in a half-century or so.

That's the cursed trade-off of scientists: you get to make excellent, clear advances but if your results are true, describing something genuinely waiting out there, then anyone else can catch you up. You end up utterly replaceable; in time, your particular style or flair long forgotten, only future historians will know that you've been there at all.

Tomorrow: the Big Bang