It may not be Pop Idol, but Channel 4 is hoping its Famelab search for scientists with charisma will do just as much for science - and its teachers - as any of its TV predecessors. The Scottish audition roadshow rolled into the Glasgow Science Centre at the weekend.

Charisma is one of those timeless mysteries, like the Mona Lisa smile or what to buy your wife for her birthday. Even people with charisma are not sure if they have it, or what it is.

“It’s about energy, liveliness, a sparkle in the eye,” says Tom Pringle, whose performances as smart but wacky Dr Bunhead enthral children of all ages. “It shines out from a person, but you can’t put your finger on it.”

“We all have our own ideas about charisma,” says TV’s Heather “The Weather” Reid. “Confidence and looks are part of it, perhaps, but you can have both without being charismatic.”

“Ian Dury (the late lead singer of the Blockheads rock group) had charisma but wasn’t good-looking,” agrees Simon Dickson, Channel 4 commissioning editor for documentaries. “Then you get supermodels, who are very beautiful but among the least charismatic people I’ve met.”

The admission that they don’t know everything is just one difference between the FameLab judges and their Pop Idol counterparts. Another is that these three are human: a young lady steps on to the Glasgow Science Centre stage, her suede high-heels clicking purposefully. She announces her name, Olivia Stevenson, surveys the audience for a second, then says “I can’t do this,” and marches off, equally purposefully.

There is a perplexed pause, then the judges speak to her supportively:

“Watch for a while, then let us know if you want another go. We’d love to hear from you.”

After a few other acts, Olivia, a student at King’s College London, announces she will try again and returns to the stage: “People say Big Brother is like watching paint dry. I think that’s unfair to paint.” She gets a laugh, relaxes, then gives an engrossing three-minute talk on the science of paint.

Scientists trying to be charismatic are generally, as Samuel Johnson remarked in a different context, like dogs trying to walk on their hind legs: “It is not done well; but you are surprised to find it done at all.”

So much more challenging than the science lessons these teachers, students and researchers deliver easily, science acts have to engage, enthral and entertain.

“Whether a keen chemist, fantastic physicist or brilliant biologist,” enthuses FameLab’s publicity material, “this is the chance of a lifetime for potential science celebrities.”

The prize for the national winner, chosen from the regional finalists and a dozen others sent from centres around the country to June’s Cheltenham Science Festival, provides some incentive - a pound;2,000 cheque, broadcasting time on Channel 4 and a UK tour of speaking events. But it is the balancing act itself that creates most strain.

Some contestants stay safely on four legs, including Ewan Polwart, a statistician who tells us about snowflakes in a lecture full of dendritic structure and six-fold symmetry.

A few courageous characters teeter on one leg, such as biology teacher Elizabeth Bohm, a tutor in molecular biology, who addresses the skull of an erstwhile pet in iambic pentameter and a long black coat: “And last your molars: they too suggest your carnivorous roots, all sharp and jagged for gnawing on a juicy bone.”

“Unique - you blended art with science and made jargon seem like poetry,” the judges tell her.

For just a few of the 40 scientists at the science centre, the balancing act seems effortless.

With a bunch of keys, a length of string, and an engaging manner, Ken Skeldon, a research assistant at Glasgow university, illustrates an obscure law of physics: “When a cowboy rides into town, he hitches his horse by throwing the rope around the wooden rail. You think it won’t hold, but the capstan effect makes it a great way to tether a horse.”

Simon Watt, a postgraduate student in evolutionary biology at Glasgow University, talks about sexual selection and the peacock’s tail, which makes the bird more visible to predators. “So why did it evolve? One theory is that females saw a peacock with a slightly longer tail and thought, ‘That’s a good looking bloke’.”

Watt continued: “This started a runaway effect, where the male children of the mating would have longer tails and the females would go: ‘Would you look at the tail on that?’ ” Then there’s David Wharton, a principal teacher of chemistry from Baldragon Academy in Dundee, who illustrates the effect of surface area on reactions.

“You’re making a plate of bangers and mash, so the sizzling sausages are ready and you want to cook your potatoes in a hurry. What would you do? You would chop them up small.”

David’s act ends with a bang, as the tiny hydrogen atoms in his test tube react explosively with oxygen in the air. The judges, too, react well:

“Enthusiastic and engaging. Very good use of voice. Held our attention.”

A clue to charisma comes from Tom Pringle’s comments: “Great to see someone doing lovely chemistry, and looking so good in a labcoat with a bald head.”

The resemblance to Tom’s alter ego, Dr Bunhead, is indeed striking, and suggests a theory about charisma. Maybe we find people charismatic if they are similar to ourselves - but without our inhibitions.

We put the suggestion to the six-month-old daughter of one of the judges, a bundle of charm with big brown eyes and a sunny smile she bestows on only the most favoured.

“Da-da-da da-da-da,” the youngster replies, in possibly the most charismatic performance of the day.

P.S. Principal chemistry teacher David Wharton and biology student Simon Watt won the Glasgow auditions.

See www.famelab.org