SCIENCE FICTION fans are generally very capacious sorts. They require the room for all the enthusiasm they store up for distant planets, evil races and old 1960s TV programmes like Lost in Space. So at 9:25 am, yesterday morning, it was unsurprising that the queue at the coffee bar of Glasgow’s SECC was populated by hefty bearded men in huge T-shirts already stretched to the limit; fearful of the consequences as their owners order a muffin or three.

The 63rd World Science Fiction Convention has landed in Scotland and fans drawn from across the globe, especially America, are massing for five days of discussion, fancy dress and listening in raptured silence to their galactic heroes.

Among the gathered authors are Anne McCaffrey, Kim Stanley Robinson and Robert Silverberg, but anyone expecting Leonard Nimoy, William Shatner or even a minor character from the cast of Buffy the Vampire Slayer is in line to be disappointed. There are plenty of other conventions that cater to cult TV and, since its inception in 1939, the World Science Fiction Convention, or Worldcon as it is dubbed, has always favoured the written word over the projected image.

Still, it’s surprising to see a printed statement taped to walls that reads: "Contrary to media reports neither JK Rowling or Iain M Banks will be attending." Rowling was hardly likely to attend, as Glasgow lacks an ancient castle in which to house her adoring young audience, but Iain M Banks, a fan favourite and regular attendee, would usually turnout at the opening of a hardback. The organisers have sold 4,500 tickets and those who have already arrived appear not to mind the absence of the world’s most affluent author and Scotland’s own answer to Isaac Asimov.

Kevin Hewitt, recently arrived from Albuquerque, New Mexico, is enjoying the damp weather - "I love your rain" - and is looking forward to attending a "coffee class" with Anne McCaffrey. "It’s limited to nine people, I just hope I’m one of them."

Hewitt is, like many devoted science fiction fans, ferociously intelligent. A research scientist specialising in high-end lasers, he credits his childhood love of science fiction heavyweights Robert Heinlein and Asimov with steering him towards a career in science fact. "Science may be my career, but I’ve never lost my love of reading about the future."

Worldcon may be focused on the future, but it has the feel of a slightly fusty past. It is ten years since it last visited Glasgow, and it seems little has changed since then. The dealers’ hall is still populated with vendors of paperback books, crystal goblets and purple velvet outfits. The most recognisable displays are still the Tardis, now curiously contemporary, a steel Terminator T100 and a Stargate, from the popular American TV series. Still, at least the sweatshirts seem new. "I’m Intersexy" and "Lighten up: It’s only Worldcon" are both doing a brisk trade.

Yet the absence of Boba Fetts, Klingons or Cylon warriors pounding the carpeted corridors and mixing with the delegates from the Seventh World Congress of Chemical Engineering, also taking place this weekend, should not be taken as a lack of enthusiasm from fans. The masquerade fancy dress awards will take place later in the week.

Instead the pulsing heart of any science fiction convention is the panel discussion. They are the warp-drive or the dilithium crystals that power the whole five-day extravaganza. Fans have flown thousands of miles to sit on hard plastic chairs and listen to bearded authors pontificate. They have prayed to the Gods of Kobal (see Battlestar Galactica) that their raised hand will be spotted and that the roaming microphone will be passed to them allowing them to pose the key question written and re-written during their long flight to Glasgow.

Torn between "The Portrayal of Science and Scientists on SF TV" and "The Plague After Next: How Are We Going to Die?", I plumped for discovering my demise. Big mistake. No mention of death rays, alien blasters or even a planetswallowing black hole. This was like one of those dreams where you are back at school in a class you can’t understand (I just scraped O-level chemistry). The panel includes Alma Alexander, a popular science fiction author who previously worked as a microbiologist, and Frank Wu, an artist specialising in striking images of alien worlds whose PhD was in bacterial genetics and patenting. He jokes: "I help huge pharmaceutical companies sue other huge pharmaceutical companies. If there is a plague, I’ll probably be suing the survivors."

Within minutes the discussion is orbiting so far above my head there is nothing to do but duck and crawl towards the door. The other panel is already packed with aficionados arguing about why The X-Files’s Scully trumps Star Trek’s Spock, and so I am left in a vacant corridor to ponder the weekend’s other panels. One that catches my eye is: "Asexuality is the New Gay: But is it also the default of Science Fiction?" A sell-out, I’ll wager, based on the number of androgynous single males wandering around lonely as a cloud of dark matter. The panel says it will appeal to the following: "In the middle of the sex scene, do you find yourself wanting to get back to the technical description of the star drive?"

For those who like their panels a little friskier and feel guilty that they prefer their science fiction art draped with scantily clad honeys in moon boots there is "Fem-bots and fairies": "Although we no longer live with the nipple shortage of the 1950s, fantasy art remains unreconstructed. Why hasn’t feminism affected SF and fantasy art?" Bound to be plenty of seats at this one, the obvious answer being that science fiction remains largely the preserve of the single male, many of whom are better equipped at dealing with alien species than the opposite sex. (These men mistakenly bought Men are from Mars, Women are from Venus and thought the plot a bit thin and the science fiction unconvincing.) More popular no doubt will be "Xena, Buffy, Hex: Is Lesbianism in Genre TV Progressive"?

There is even a panel called: "How to Participate in and Moderate a Panel". Yet the one that threatens to flick the rawest nerve among sci-fi fans is one entitled: "Are We No Longer Special?" This panel examines the current debate among veteran sci-fi fans that, as Hollywood and TV become increasingly obsessed with their genre, and the world we live in more closely resembles a future previously imagined, have geeks become mainstream?

I decided to track down one panellist, Charles Stross, the Edinburgh author who is up for three Hugo awards, the Oscars of the sci-fi community. "Two are in the same category so I’ll lose at least once," says the English computer programmer, who has clearly embraced the pessimism of his adopted nation. "At the moment, 36 per cent of Hollywood’s output seems to be science fiction and Lord of the Rings won 11 Oscars, so it is in many ways now the mainstream. However, fandom has fragmented. It is much more specialised. You have Trekkers, experts on animé, Buffy fans, Tolkien fans, they all have their own conventions. Worldcon is much more focused on the literary field, on the written word, and we are still trying to claw out of the ghetto toward respectability."

What has happened, Stross believes, is a dilution in that insufferable conceit some science fiction fans had that they were a knowledgeable elite. "Comic book guy" in The Simpsons is the perfect parody. "We were kidding ourselves about our importance to the real world," says Stross. "You’ll still get guys with an array of badges to demonstrate their importance, but that just excludes people. I think fandom is more inclusive now."

Outside the registration hall Cindy Somebody Cabal - it even says so on her US passport - is wearing pink from the dyed hair on her head down to her pink-painted toes. Pink canvas bags, pink jacket, pink trousers, pink eyebrows. Her bare arms are tattooed with fairies. A resident of the bay area in California, Cindy says she first came to a Worldcon to chase a boy. She lost the boy, but found a deeper passion for science fiction and fantasy novels, particularly those of Anne McCaffrey: "I’m a freak but here people laugh with me, not at me."

So are she and her fellow fans still special? "My answer is yes - absolutely."