Google hired the 64-year-old in 2005 as its vice-president and 'Internet Evangelist'. Heralded by Google chief executive Eric Schmidt as "one of the most important people alive today", his career began in academia and the American military's quest to develop nukeproof communications, before moving into commercial telecommunications and now Google.

Indeed it's tricky to untangle whether Google is using Cerf to generate enthusiasm and ultimately global take-up of the net . . . which of course creates a larger customer base for Google . . . or if Cerf is using Google to further his own aim . . . likely to be the same goal but perhaps for more humanistic reasons.

When Cerf was offered the Google job, he had to pick a title. 'Archduke' was his preference but it was decided possible comparisons with the assassination of Franz Ferdinand precipitating the first world war might tarnish his (or Google's? ) image. 'Evangelist' better suits Americans' proselytizing style anyway.

"I think a successful engineer or scientist has to understand how to communicate and find the right level of abstraction at which to communicate to particular audiences. My favourite problem is figuring out how to convey a particular idea to someone who doesn't necessarily have the technical background, but I want them to go away with a working model in their heads, " says Cerf.

"And members of Congress are my favourite stalking horse for that target, " the chairman of the influential Internet Corporation for Assigned Names and Numbers (ICANN) added mischievously.

A winner of the 2005 Turing Award, known as the 'Nobel Prize for Computing', Cerf is by disposition a futurist, constantly anticipating the bends in the road ahead along the global information superhighway he helped to lay.

However, it is the backward-looking work of historians that is engaging him at the moment.

Cerf is concerned about what he terms 'bit rot', the process by which data stored digitally today may become unreadable in the future.

"As time goes on, the bits that we store are only understandable if we have software that understands them, " he says. Sometimes this forward compatibility doesn't work so the preservation of the application that produced this data is also necessary. "We should then start worrying about whether to keep the operating system that runs the application that interprets the bit. Then we have to worry about keeping the hardware that knew how to run the operating system. Then we get the intellectual-property question of who is allowed to keep the operating system alive for a thousand years? Is this the responsibility of the original creator of the operating system, the application or something somebody else undertakes? I don't know the answer to this."

Of course the question is also pertinent to Cerf 's employer. "The worst thing in the world is if we [Google] direct someone to a data file they can't interpret, " he said. "This is an example of how having a theory to stave off bit rot is very valuable, but is ultimately useless unless it is applied. There is a business opportunity here and whether it's Google or not is open to debate."

The question Cerf does profess to have an answer for concerns the internet running out of addresses for all the computers connected to it. Cerf 's initial genius was to create the Transmission Control Protocol (TCP/IP) in 1982 which allows new applications and subnetworks to be added to the internet at will, regardless of complexity. The mobile internet is a good example. However, with global internet penetration standing at 16.9%, or 1.114 billion permament users, and the current internet protocol only capable of 4.3 billion terminations, addresses wil run out by 2011 as take up increases at current rates. "We have to upgrade to internet protocol version six with four trillion, trillion, trilion addresses. Now. That's enough to last at least until I'm dead and then it's someone else's problem."

Cerf, a visiting scientist at Nasa's Jet Propulsion Laboratory, says bit rot is also a major issue for the US space agency because vast quantities of data from its missions are stored on old iron oxide tapes which will disintegrate next time they are played back.

The topic of space is clearly a passion as well as a profession for Cerf. He is currently working on plans to create an upgraded internet protocol that will take into account the stellar distances, time lag and disruption cosmic particles cause on data transfer in space. The plan is to use satellites and other functioning vehicles scattered throughout the solar system to act as network relays, and after nearly 10 years Cerf and colleagues have got to the stage where they're ready to formerly request NASA to allow them to upload the software necessary to run an interplanetary network onto an underused space vehice left over from the 2005 Deep Impact mission.

"We are satisfied that we can make it work; we've done terrestrial testing with the military and civilian sectors, underwater acoustic testing with the [US] Navy and surface testing with Marine Corps. We've a solid design now but we need to demonstrate it physically on space platforms before we can get anyone to commit to using it on a real mission."

So how excited is he about all this? "It feels like I'm living in a science fiction story sometimes. I mean, you're sitting around a table and somebody says: 'How long's the roundtrip to Jupiter?' Or, 'Solar power isn't gonna hack it . . . I need a nuclear reactor, or maybe isotopic radioactive power supplies in space for this.'" Returning to Earth, Cerf is au fait with Ireland's technology set-up and served on a government telecommunications advisory panel in the late 1990s. "An interesting experience, " he recalls. He names senior Irish civil servants as personal friends and said he would offer his services to any future similiar committee as long as no conflict of interest arose because Google's European HQ is in Dublin.

"Ireland is a small enough place, so during the day we would debate telecommunications policy, then report to minister Mary [O'Rourke] in the afternoon who would report to the Taoiseach in the evening. The next day we would hear that they were starting to implement stuff we had been talking about the day before, and we had to say: 'Wait! We haven't fully figured this out yet!' There was this absolutely incredible rate of progress and I think the telecoms policy of the country was substantially revised as a consequence of that particular committee."

The Virginian is understandibly not up to speed with Irish politics and seemed unaware former enterprise minister Mary O'Rourke came under heavy criticism for her role in the privitisation and floatation of Telecom Eireann, contributing to the loss if her Dail seat in 2002.

"I actually have a lot of resonance with the Irish situation because you guys have done remarkably well over the last 25 years, taking advantage of your position in the EU and ploughing investment dollars into information technology and telecoms. It's a very enterprising place."

Cerf 's advice for Ireland Inc at the moment echoes his experience of working in competitive and fast-moving areas of new technology and computer science: "Just forget the other guys and get busy."

For himself, the greybeard of youthful Google has only one goal: "To wear out two 26year-olds every day."

He would like to be remembered simply as someone who contributed to the information revolution and demanded democratic access to the world's information.

"Everyone should share access to content, but 5.5 billion people are not connected, " he said. Yet.

CV

VINT CERF

Job: Google vice-president and internet evangelist
Career: 1976-1982 US Department of Defense, Advanced Research Projects Agency 1982-1986 MCI 1986-1994 Corporation for National Research Initiatives 1994-2005 MCI 2005 to present Google Education: Stanford BSC Maths, UCLA's second ever PhD in computer science 1972
Home: Washington, travels extensively for Google
Family: married to Sigrid, two grown-up children aged 29 and 34
Hobbies: avid reader, particularly science fiction