Monday: a science lecture at Stanford. Tuesday: Japan. Wednesday: Hong Kong for an honorary degree...

'Back to Japan for more engagements and a lecture on Saturday. Monday: back to the UK for funding council meetings and then off to Poland for two lectures. Today, Wednesday, is the first time I have time to myself for almost a month and I am talking to you!'

The non-stop jet-setting, globe-trotting demands on laureates are an indication of the huge international prestige that attends to the Nobels. But the awards are as much an imposition and burden as they are an opener of doors

Harry Kroto, the 1996 chemistry Nobel prizewinner, reels off his engagements for the previous week. "Monday: a science lecture at Stanford. Tuesday: Japan. Wednesday: Hong Kong for an honorary degree. Back to Japan for more engagements and a lecture on Saturday. Monday, back to the UK for Higher Education Funding Council meetings and then off to Poland, where I have two lectures. Today, Wednesday, is the first time I have time to myself for almost a month and I am talking to you!

"I've got a request to act as a referee for an award for a professor, and I have an email from "Brett", who is a high-school student in California who wants me to offer him some advice. Tomorrow, a television company is going to film me discussing my thoughts on the song "Imagine" because it was my final choice on Desert Island Discs ."

In the past two months, Kroto has covered much of the globe: East Asia, Mexico, Washington, Minnesota, central Europe, Italy, California. He has just returned from Stockholm where he celebrated the centenary of the cause of much of his back-breaking workload - the Nobel prize - with another round of lectures and interviews.

"To be honest, it is just a long list of people who want something from me," Kroto says. "It is killing me. I'm quite exhausted."

It is probably in the diaries of its laureates that the true nature of what the Nobel prize has become in the 100 years since its creation can be best assessed. There are richer prizes: the Templeton Prize for Progress in Religion is specifically set at an amount to exceed the Nobel of the same year. America's Pulitzer Prize, Britain's Booker Prize, the Royal Society medals in science and the Fields medals in mathematics all have proud traditions. Israel awards its Wolf Prizes, Japan celebrates the Kawabata literature prize and the UK has its lords, sirs and dames. But the Nobel prizes outshine and outreach them all.

As Burton Feldman, author of The Nobel Prize : A History of Genius, Controversy and Prestige , points out: a Nobel prizewinner immediately enters a kind of aristocracy of "our democratised, scientised, secularised modern culture". However narrow the specialism that has earned them the honour, they can expect to be asked to pronounce on anything from the organisation of society to the merits of pop songs. The New York Times reported on the phenomenon when Einstein visited New York in 1930. "Within one brief quarter of an hour, [Einstein was asked] to define the fourth dimension in one word, state his theory of relativity in one sentence, give his views on prohibition, comment on politics and religion and discuss the virtues of his violin," the paper said.

But, as Kroto's itinerary makes plain, it is the Nobel's global reach that sets it apart. Go anywhere in the world and the Nobel name will most likely be revered. Indeed, the farther you get from the main breeding grounds of prizewinners - the United States and Western Europe - the greater the authority the Nobel name appears to wield.

Japan, one of the world's most highly developed countries but grossly under-represented on the Nobel podium, has gone so far as to set a government target of 30 Nobels for scientists in the next 50 years (a fivefold increase on its success over the past 50 years), and in April the Japan Society for the Promotion of Science established an information office at the Karolinska Institute, the awarding body for the medicine prize.

According to Antony Hewish, the joint 1974 physics laureate: "In developing countries, they put you on a higher pedestal. In places such as Korea and China it is particularly noticeable. They think the prize is more important than you would find in Britain because it is a symbol of entrance, acceptance." Kroto talks of being dealt with almost as a "god" in some parts of East Asia.

Wole Soyinka, who won the Nobel prize for literature in 1986, believes the experience of being a Nobel is still more extreme for the few third-world citizens to have been anointed. After winning his prize, he flew home to Nigeria to be greeted by massive crowds. He has described his experience of becoming a third-world country's only Nobel as like going into "public ownership".

The effects of the prizes' enormous international prestige are not always positive. Soyinka's Nobel at one time put his life in danger from the Nigerian government because the importance attached to his views inside and outside Nigeria made him more of a threat to the corrupt regime. The Egyptian novelist Naguib Mahfouz, who was awarded the literature Nobel in 1988, was stabbed by a religious militant in 1994 after being denounced for his western links following his Nobel triumph.

Some peace laureates such as the Soviet dissident Andrei Sakharov and the Burmese democracy campaigner Aung San Suu Kyi may have found partial protection from the world attention attracted by their awards, but other winners have suffered. The American civil-rights leader Martin Luther King and the Middle East statesmen Anwar al-Sadat and Yitzhak Rabin were all assassinated by extremists after getting their prizes. Feldman links their deaths directly to the honour: if the Nobel is the ultimate symbol of international achievement, the assassination of a prizewinner must be the ultimate repudiation of that achievement, he says.

Another negative spin-off, ironically, is that the onus it places on laureates - and the expectations - means that they often have little time to do the very thing they won the prize for. For example, Wislawa Szymborska, the Polish poet (see right), says the award gave her writer's block.

If there is a dark side to the Nobels' fame, the achievements have also been startling. Here, Feldman believes, distinctions must be drawn between the different prize committees. The most notable success, the very basis of the Nobel's international reputation, has been built on the science prizes. Feldman argues that despite their international reach, the peace and literature awards can still be seen as "basically western institutions with a global aspect", largely because of the divided and heterogenous nature of the constituencies they are asked to cover. But, he says, the Nobel science prizes have established themselves as key institutions in genuinely international scientific cultures.

"In fact, I think we can go further in our claims for the Nobel here. It is arguable that not only have the Nobel science prizes profited from the development of a global scientific community in the 19th century, but that they helped create it," Feldman says. "People forget that science before the Nobel prize was a splintered affair - the French with their institutions, the British with theirs, and so on. The Nobel necessitated international networking and discussions that may have played an important part in internationalising science. It continues to do that with countries that are trying to join the world scientific community. We may have more to thank Alfred Nobel for than we think."

The Nobel Prize : A History of Genius, Controversy and Prestige is published by Arcade Publishing, £11..

Chris Bunting

Writer's reward brings on block

Polish Nobel literature laureate Wislawa Szymborska does not like to give interviews. The 78-year-old poet, who lives in Krakow, has given "something like ten in her entire lifetime", says her personal assistant Michal Rusinek. "She says it is not her form of expression. Even if she had some free time, she would probably say no."

It is a characteristic response from a poet whose 16 collections published since her first poem in March 1945 "Szukam slowa" ("I am Looking for a Word") have been translated into dozens of foreign languages including English, German, Hebrew, Swedish and Serbo-Croat.

Since 1931, Szymborska has lived in Krakow - where she graduated from the Jagiellonian, Poland's oldest university, in 1948. Her friends and associates say she shuns publicity and suffered crippling writer's block after her 1996 Nobel award.

Michal Cichy, a literary critic from Gazeta Wyborcza , one of Poland's leading national newspapers, said such was the weight of international expectation she felt after the award that she "didn't write a word for months and months".

Joanna Szczesna also works at Gazeta Wyborcza , which recently republished a series of essays written by Szymborska during her 30 years as poetry editor and columnist at the Krakow literary weekly Zycie Literackie. She is also Szymborska's biographer. She confirms the poet's retiring nature. "She's published only five or seven poems since getting the Nobel prize. She resents the disruption of her privacy."

Nick Holdsworth

100 years of the Nobel contents page