By Peter Bowes
BBC News correspondent, Los Angeles
A look around the state-of-the-art 'green' house at TED 2009
Some of the world's most inspirational speakers and thinkers are starting a mass brainstorming session in California.
The Technology, Entertainment, Design (TED) conference, which is celebrating its 25th anniversary, attracts goal-driven entrepreneurs, inventors, geeks and dreamers. The elite group, known as TEDsters, discuss everything under the sun and has a collective aim of making the world a better place.
"The purpose of TED is to bring together a group of remarkable people from every discipline you can imagine and then give them a chance to get each other excited," says Chris Anderson, Curator of TED.
"We invite people to share what they're passionate about or experts on - and in a way that's accessible to other people. What happens every year is that people make all kinds of unexpected discoveries by thinking outside their usual comfort zone, and they learn from unexpected places and they get inspired by other people."
Some of the energy-saving gadgets at TED2009
It is not an event for the casual passer by. 1,500 invitation-only attendees each pay $6,000 (£4,174) to be part of the elite gathering.
To qualify for a ticket, TEDsters must persuade the organisers that they have something educational or inspirational to contribute. The registration form includes essay questions.
"Not everyone who comes is rich," explains Mr Anderson.
"For a lot of people it's a massive stretch to pay that kind of money, and especially in the current environment."
He adds that many view the experience as a "mental recharge." Participants are given precisely 18 minutes to give "the talk of their lives."
This year, the event is also offering a fellowship programme to give aspiring world-changers in impoverished communities a chance to be part of the TED experience. The programme is focused on involving remarkable people from Asia, Africa, Latin America, the Middle East and the Caribbean.
"Really, the only thing they have in common is a passionate curiosity. They just want to learn about the world, be inspired and excited by ideas," says Mr Anderson.
TED's 25th anniversary will have 1,500 attendees who pay to speak to the world's leading technology minds.
The event does not discriminate between its participants. There are no 'keynote' speakers although an appearance by Microsoft co-founder Bill Gates on Wednesday will be a highlight of this year's opening "Reboot" session.
Past speakers include former US president Bill Clinton, Google founders Serge Brin and Larry Page, Wikipedia creator Jimmy Wales and rock stars Bono and Peter Gabriel.
TED was a key launching pad for Al Gore's film, An Inconvenient Truth.' The former Vice president presented his slide show at the event shortly before the film was released.
"He galvanized dozens of people to really boost the distribution and awareness around that film, and the producers credit TED, I think, with boosting its impact," says Mr Anderson.
As well as the talks, TED 2009 will feature exhibits designed to fuel the imagination about how we live in the 21st century and protect the environment.
In the last few days a pre-fabricated house has been constructed on the plaza outside the conference centre. The factory-built home features state-of-the-art technology and a sustainable design that promotes a green way of living.
It features environmentally safe products and energy-saving plumbing. When the TED meeting is over it will be opened to the public and the home will go on sale for half a million dollars.
The aim of the conference is to allow the latest thinking in three main areas, that affect our lives, to be shared. Under the heading "Ideas Worth Spreading" the talks are made available online.
"In the internet age, someone can give a powerful talk, it can be captured on film and it literally can spread around the world and reach millions of people, explains Mr Anderson.
"Ideas that make people see the world in a more interesting, a more nuanced, a more real way, and inspire them to think differently about the future.
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