Prof Richard Wiseman from the University of Hertfordshire is an expert on laughing, giggling and guffawing. He even has his own iPhone app. He's giving a talk at the Royal Institution on Wednesday 31 March.

We also reveal the world's funniest joke as told by people on the streets of London.

The European premier of the new Imax film, Hubble 3D, has taken place at London's Science Museum. David Brower tells us about the complexity of rendering some of the fly-throughs, including the 'star' of the show, the Orion nebula.

A new exhibition at the Royal College of Art attempts to predict some of the ways current research will help create future technologies. Producer Andy visited Impact.

Nell Boase is your host while Alok is away.

Feel free to post some of your terrible (but clean) jokes on the blog below.

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Follow the podcast on our Science Weekly Twitter feed and receive updates on all breaking science news stories from Guardian Science.

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Andy DuckworthNell Boase

It was a little film that became an instant classic. As The Railway Children celebrates its 40th birthday, Patrick Barkham catches up with the original cast

The Railway Children will always be remembered for that scene at Oakworth station, the one where Roberta's father emerges through the steam of a departing train. "Daddy, my Daddy!" Plenty of people will admit to weeping when the young Jenny Agutter is reunited with her father. But watching it now, 40 years after it was first released, I find myself welling up long before then: at the birdsong, the music, the Yorkshire countryside, the lost Edwardian world.

Why does it make me cry? "Because you're an old sentimentalist," says Bernard Cribbins, who played Perks, the station porter, and is now an astonishingly frisky 81. "Which would apply to most of the audience who watch The Railway Children." Does Agutter cry? "No, she's hard as nails," says Cribbins. "You have to be an extraordinary person if you don't have a bit of a gulp."

Since it was first published (in serial form) in 1905, Edith Nesbit's tale of a family forced into penury after the mysterious arrest of their father has never been out of print, and has spawned three television series, two films and several plays. The definitive version, the 1970 film directed by Lionel Jeffries, has now been digitally restored; the memories are still fresh for Agutter, Cribbins and Sally Thomsett, who played Roberta's younger sister, Phyllis.

"People still go to me, 'Railway Child!'" says Agutter. She was cycling in London recently and a bus driver swore at her. "These two guys coming towards me said, 'What's his problem? Didn't he realise you're a Railway Child?'" She thinks about the way Jeffries put the "Daddy, my Daddy" scene together. "The sound goes, so that your reality is suspended. He uses this beautiful music and when the mist is going you just hear this 'ping', this tiny sound, and there's this character coming out of the mist. And you see her running towards him and then you see her feet go off the ground. All those images are just heartbreaking."

The three "children" had an unusual bond on set because they were guarding a secret: while 17-year-old Agutter was close to Roberta's age, Thomsett, playing 11-year-old Phyllis, was already 20. The producers ordered her not to reveal her age to anyone. "It was in my contract: I wasn't allowed to do anything that anybody over 16 could do," says Thomsett. "I couldn't have a cigarette, I couldn't go out with my boyfriend and I couldn't drive my car. I had a fabulous new red Lotus that I just loved. I was sworn to secrecy."

One night, a frustrated Thomsett fled with Agutter to a nightclub in Leeds where a bikini-clad woman danced inside a cage. "We sat down, ordered a drink and a couple of boys came over to ask us to dance," says Thomsett. "The next thing I knew, Lionel Jeffries and our producer were standing there. We were caught red-handed."

Agutter, who had already filmed Walkabout, thinks that working at such a young age probably arrested her development. "You are put among people who are no longer your peers, so you are not trying things out at the same time – the experimental nature of adolescence goes by-the-by. I hadn't really been through any great emotional changes. When I went to America in my 20s there was a delayed adolescence, which Hollywood supports in an awful lot of people."

She eventually returned to Britain, married and became a mother. In 2000, she played Roberta's mother in the TV adaptation of The Railway Children. Which production does she prefer? "Er, you can't ask me that. One is attached to my childhood and one is attached to my being a mother. That's why it worked for me. I would come across people [who] were quite cross. They felt playing the mother was a betrayal of having been Roberta."

The day after we meet, there is the sad news that Lionel Jeffries has died. Agutter, in particular, has very fond memories: "I see him vividly with his red scarf around his neck, larger than life, being in command." He was only two years older than Cribbins, but she fears his later years were tough; despite his talents, he did not always get work.

Over the years, Agutter has become something of a Railway Children scholar and hopes to make a movie about Nesbit's unconventional life: a radical socialist, she lived in a chaotic ménage a trois with a serially unfaithful husband and an unhappy son, who later committed suicide. "She's this wonderful children's writer, but actually she was a mess."

We cry when we watch The Railway Children, Agutter says, because we are mourning our own lost innocence. "You cry because of your sense of yearning. That is what is in her book and that is what Lionel so cleverly gives people. People cry at their own sense of loss, that they don't have that magic they had when they were little. You suddenly become that child again, believing in something that you feel you've lost."

The Railway Children is screened at the National Media Museum, Bradford, on 28 March as part of the Bradford film festival (nationalmediamuseum.org.uk), and is at selected cinemas from 2 April.

• Children and teenagers

Patrick Barkham
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She won an Oscar for a dramatic role in The Blind Side, so could this be the end of Sandra Bullock, 'romcom chick'? Plus, she explains why playing a Christian Republican was so difficult for her

Sandra Bullock has been doing interviews all day in a Beverly Hills hotel suite, but she's still full of energy when we meet, and is as witty and self-mocking as a fan might expect from her film roles. Oddly, perhaps, she's rather more slender and pretty in the flesh than on screen.

We're here to talk about her performance in her new film The Blind Side, which is based on a true story – the film for which she has since won an Oscar. She plays Leigh Anne Tuohy, a well-heeled, white Memphis woman who takes in a homeless black teenager, a giant, almost silent man-child called Michael Oher, then mentors him through high school to a football scholarship at her alma mater, the University of Mississippi.

The film could not have served her better, but then last year was a good year, professionally at least, for Bullock. Indeed if ever an actor had a full-spectrum, 360-degree banner year to celebrate, it was Sandra Bullock in 2009. ("Hey, every year's a banner year!" she mock-protests.) First The Proposal, a romantic comedy of the type she has been honing to a fine, gleaming point for about a decade now, made an estimated $320m at the box-office on a mere $40m outlay. Meanwhile, The Blind Side, late in the year, crossed over in its second and third weekends to a more conservative audience that often dodges Hollywood product. Directed by John Lee Hancock, it has made more money than any previous movie featuring a single above-the-title female star: $265m and counting.

As often happens in the Hollywood crapshoot, Bullock was initially underwhelmed by the part that was to win her an Oscar. "I mean, I loved the story but I didn't know how to play her – and it was a while before I got there," she says. "The director said, after about eight months, 'Why don't you go and see Leigh Anne and see what I'm talking about? It'll explain her.' I met her and was really blown away by the energy she had. I stopped thinking about it like an actor just seeing a part, and the story is what finally got me."

The Blind Side comes adorned with aspects of casting and storyline – especially its emphasis on the three F-words of the South: Faith, Family, and Football – that seem designed to court a more conservative audience. Country superstar Tim McGraw plays husband Sean Tuohy, a franchise-restaurant millionaire. The film's biggest laugh comes when McGraw, discovering the tutor they have hired for their adopted black son is a liberal, says to his wife: "Who'd have thought we'd have a black son before we ever met a real live Democrat?"

But Bullock disavows any plan to aim for that slice of the market, even when I suggest that such a move is fully in the spirit of the age of Obama, reaching sincerely across the aisle to an audience that often feels scorned by liberal Hollywood. "Nope, not on my part, and I know it wasn't on the director's part," she says, shaking her head adamantly. "[The Tuohys] are devout Christians and they're Republicans and they sure love their football. Me? I know nothing about Christianity, nothing about football, and I'm not a Republican. But John Lee Hancock had always told me this is a mother-son story that just happened to involve people that you might normally pass judgment on. I go, 'Hmmm . . . white, Southern, Christian, Republican . . . not the kind of people I feel comfortable around, because they're usually not appreciative of me, or the lifestyle I supposedly lead. So I automatically assume that they'll reject me because of all that. But this family was the exact opposite."

In the movie Bullock has a well-crafted Memphis accent and frosted-blond Big Hair, and the transformation is fun to watch – "You know, I would not make a good blonde; it's just too much work" – but the Alpha-Mom role never really strays far from the no-nonsense, stiff-necked workaholics Bullock plays in many of her comedies ("art imitating life!" she chortles).

I task Bullock with some of the things that have troubled people about The Blind Side. Some have called it "Precious for white conservatives", noting that Oher, the black teenager at its heart, is either a cipher for white-paternalist guilt or just the means by which a rich white lady finds another side of her soul. And we really don't know much more about Michael Oher at the end than we did at the beginning. In response, Bullock seizes merely on the notion that it's rightwing. "Well, of course it's rightwing. They're rightwing characters, but I want to know – what parts [of the actual movie] are rightwing? I mean the family are Republicans, so that's certainly rightwing, but otherwise I don't know what it means. Aren't we supposed to show both sides? People go, what is the hardest thing about playing this? And I go, playing a Christian Republican – and making sure I believed what I said!"

So it's not the movie's fault that Sarah Palin likes it? "Oh Jesus! Please!" she guffaws, rolling her eyes, more at the mention of Palin than at the question (I think). "If it hadn't been successful people never would have said it was rightwing, but it is successful so I think they've just gotta hack away at it somehow."

At 45, Bullock is a mega-star, but despite all the hit films she has starred in, she has never seemed at ease with the rigmarole that goes with being a celebrity. I ask her – and this is of course a while before she wins the Oscar – how the whole pre-Oscar whirl is treating her. "Leaving my house and getting on to a red carpet is always crazy for me, because you have to find a way to be comfortable in the most uncomfortable situation imaginable. How do you talk yourself down so it's all water off a duck's back? It's a world that's not mine – I just come in and do my job and then go back home."

This is, of course, self-deprecatory rhetorical boilerplate in the time-honoured best actress nominee tradition. She knows it, I know it. In reality, Bullock has been working the talk-shows for weeks now, literally morning (Good Morning America, The Today Show), noon (Oprah, The View), and night (Letterman, Leno, et al), although she is laying off a bit now that the momentum seems to be going her way. In the room next door to where we're talking is Bullock's publicist Cheryl Maisel, a powerhouse PR consultant previously associated with Tom Cruise and the Beckhams, so obviously nothing is being left to chance here. There is a machine behind this Oscar bid, as there is with all the others, but its gears and cogs grind away offstage, only dimly audible to us civilians.

Just to balance her karma, Bullock also won the Golden Raspberry award for worst actress for her third movie of 2009, All About Steve. The film was a thudding flop, reeking of the delayed-release shelf, about a slightly eccentric woman love-stalking a TV newsman.

"You've gotta take both sides," she says, when I ask her how she feels about the nomination. "If you take either one too seriously, shame on you, and if you disregard the other because it's not all you want it to be, then shame on you too. You should be a good sport about it – we're not curing cancer here."

Part of the reason why Bullock has always seemed a bit different from your common-or-garden Hollywood A-lister is her slightly unusual choice of spouse, and – until last week anyway – how private she has managed to keep her private life. Her husband of five years is motorcycle builder and stuntman Jesse James, and when we meet, Bullock knocks back questions about their life together like deftly fielded shuttlecocks; they pile up at my feet unanswered, or barely answered. When I suggest there's a similarity between Tuohy adopting Oher and Bullock (who has no children of her own) taking on James's three children from previous relationships, she waves the suggestion away with a laugh. I ask about James and Bullock's rough custody battle over the child he had with pornstar and jailbird Janine Lindemulder, and she merely deadpans, "Life sucks a lot of the time, everybody get used to it. That one had a happy ending."

This may, with hindsight, have been a bit premature. Last week Bullock abruptly pulled out of the London premiere of The Blind Side after James was accused, in a celebrity magazine, of having an affair with a "tattoo model". He has since apologised publicly to Bullock for the grief his actions caused, although he denied the "majority" of the allegations.

Anyway, coincidentally or not, Bullock didn't thank her husband when she got her Oscar. But she did thank her mother Helga – profusely and tearfully. A German opera singer who married John Bullock, an American voice coach, and died in 2000, Helga raised Sandra and her sister Gesine partly in Germany and took them along on Bavarian singing tours in which they were encouraged to perform.

This experience obviously gave her a love of performance – voice lessons, ballet, practice every day. "I think on some level, yes, it was inborn. I thought it would be theatre in New York. That's what you strive for, study for, dream of. We never had like, celebrity magazines in the house, just the Post and Newsweek, so that whole celeb path was not something we even thought of."

As a teenager living in the same northern Virginia suburbs, I used to drive right past Bullock's high school to my burger-slinging McJob, so I ask her which shopping mall she used to hang out at.

"Oh, Tyson's Corner was the nearest, but I wasn't allowed to go. I wasn't allowed to get in a car with anyone except family until I was 18 years old. My mother was real smart, she pulled the reins very tight. I wasn't allowed anywhere!"

After studying drama at East Carolina University, she moved to New York, attended acting classes and appeared in the odd student movie and off-Broadway play before being spotted. "Getting into television was a total fluke. Random audition out of Backstage magazine. You get a part in a play, someone sees you, suddenly you're zipped off to California and you're like, 'Oh this is odd, but hey, I'm working, paying the bills.'"

Her early roles weren't auspicious; one job was second-string in Bionic Showdown: The Six Million Dollar Man and the Six Million Dollar Woman. "I wouldn't trade those early parts for anything," she says. "They're all steps on the way to being right here." Thereafter she netted parts in movies large (Demolition Man) and smallish (Love Potion No.9) before her out-of-nowhere double-smash with Speed and While You Were Sleeping in 1994-5. The first briefly turned her into, as she says, "action-movie chick", while the other signposted the "romcom chick" side that has since predominated, although she's never been happy with the term.

"Usually comedy is only available to us ladies in the romantic comedy. That's why I hate romantic comedies. I want to make comedic-comedies – let's get back to being funny!"

The 90s saw Bullock co-starring with then-bankable male leads such as Matthew McConaughey (A Time To Kill), Harry Connick Jr (Hope Floats), and Ben Affleck (Forces of Nature), and since 1996, she has also produced many of her films. Although the last decade has seen the consolidation of an identifiable Sandra Bullock "brand", or so it feels, she claims there's "no brand", that it's all just a fluke.

Did she feel the world changing around her as she became better known? "Definitely. You realise after something like While You Were Sleeping that in the near future you'll no longer encounter people who don't have a preconceived idea of who you are. I saw that – and it made me sad."

Her remedy for this has been to keep her distance from Hollywood. She lives mainly an hour south of LA, and keeps houses in Texas and Georgia. Does she regard the movie business as meaningless and empty? Is she wary of celebrity culture?

"Oh yes. Because it is meaningless and empty!" she laughs. "I'm not wary of it, though – I'm just aware. It holds nothing for me, although it will hold a great table in a restaurant, when you're at your peak. If you don't have other real things in your life that you love just as much, then you will drown in it."

Surprisingly for an Oscar-winner, but perhaps less surprising for a woman who knows that "the only power you have in Hollywood is the power to say no" and who has previously, and happily, taken extended hiatuses from film-making, Bullock has absolutely no idea what she'll do next.

"There hasn't been anything around lately that I want to produce – I mean literally stay there night and day and produce. Something might come up that I absolutely love, and I'll do it, but really, there's no plan, there's no brand. It's just timing that's been very good this year and you know what? Next year it's probably not going to be so good, and there'll probably be the backlash, and the whole 'What did we see in her in the first place?' You know the way this happens – the tide will always go out, no matter what."

The Blind Side is released on Friday 26 March

• Sandra Bullock
• Celebrity
• Comedy
• Drama

John Patterson
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Front Page: MLK drama defeats heavyweight plays for top prize -- Katori Hall beat heavyweight play contenders "Jerusalem," "Enron" and "Red" to the top play prize.

Front Page: MLK drama defeats heavyweight plays for top prize -- Gotham-based dramatist Katori Hall beat heavyweight play contenders "Jerusalem," "Enron" and "Red" took the top play prize at the 2010 Laurence Olivier awards in London.

Volunteers offer Disney and Pixar favourites to youngsters traumatised by natural disasters in Haiti

Dusk falls, the insects bite and a makeshift open air cinema screen is set up. Scores of children gather and are transfixed by the flickering images that, for a short time at least, help them forget their troubles.

While the aid agencies are trying to make sure youngsters in Haiti have access to shelter, food and water, British volunteers are offering comfort through the medium of film.

Led by film enthusiasts from the Bristol's leftfield Cube Cinema, the project involves showing feature films and messages of support from children in Britain. The idea is eventually to help youngsters in Haiti make their own films, which will then be sent back to Bristol, forging a cinematic link between Britain and the earthquake-hit Caribbean country.

Esther May Campbell, a Bafta award-winning director, Cube volunteer and one of those behind the Haiti Kids Kino Project, said they hoped to offer traumatised youngsters a brief escape.

"This is the most direct humanitarian response we can offer," she said. "When children who have suffered these kind of traumas have nothing to do, desperation and anxiety levels shoot through the roof. The Cube has skills, passion and networks, enabling us to create a mobile cinema for young people, intending to offer community, hope and distraction."

Films the volunteers in Haiti have in their repertoire include Disney and Pixar favourites such as Jungle Book, WALL-E and Up, and European classics such as Albert Lamorisse's The Red Balloon. Charlie Chaplin and Buster Keaton films will also be screened as well as Looney Tunes cartoons and even the Wombles.

Campbell said the selection had been made carefully so that children who could not speak English would still enjoy the movies. Up to 500 children have been attending screenings.

French language films such as Le Ballon d'Or, a film about a talented footballer set in a poor west African community, has gone down well. But another highlight for the two Cube volunteers in Haiti, Marko Wilkinson and David Fitzsimmons, has been the sight of an audience clapping along to Vic Reeves singing Life's a Treat from Aardman's Shaun the Sheep. "There's more demand than we can supply," said Wilkinson.

The pair's work has been made more difficult by rain. One screening had to be abandoned when torrential rain fell and the project is now having to look at ways of protecting equipment against the damp.

As well as the feature films, Wilkinson and Fitzsimmons have taken out "film postcards" – short messages from youngsters in Bristol. One of the most striking "postcards" is a Bristol youngster holding up a sign that read: "Bon jou" – "Hello" in Haitian Creole.

The UN acknowledges that it is important to give children in disaster zones something to do.

Patrick McCormick, emergencies communication officer for the UN, said: "The worst thing for children in natural disasters isn't just the damage that they see around them, but also when they sit around with nothing to do. It ramps up anxiety and despair, and that's what does even more damage."

The Cube wants the project to be a long-running affair that eventuallybecomes self-sufficient. It is inviting people to donate by buying a seat for a screening in Haiti. If, as seems probable, they cannot actually get there, the ticket will be passed on to a local person.

The Cube, which describes itself as a "microplex", has a proud history of setting up interesting cultural exchanges and creating cinemas in challenging locations. Previously it has screened films in locations ranging from a Cornish tin mine to an abandoned multi-storey car park.

• Haiti
• Natural disasters and extreme weather
• Volunteering
• Children

Steven Morris
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The director reveals that he is on a shortlist to helm the behemoth Marvel Comics adaptation.

Diary of a Wimpy Kid fares well in second place with $21.8 million.

Reports say that 20th Century Fox is actively looking for another director to take over the project.

New images from the area where this Kenneth Branagh directed Marvel Comics adaptation is taking place.