What is happiness? There are as many different possible answers to this question as there are people - and dogs - on the planet, but perhaps, to paraphrase Supreme Court Justice Potter Stewart, we simply know it when we see it.
Now, The Happiness Project is a brand new production that explores our understanding of happiness and well-being. It brings together a company of young artists aged 12-19 and six scientists and academics to create a piece of contemporary theatre coming to London's Roundhouse Theatre.
"We were keen to create a space onstage where all these people could come together to share their conversations with the audience," say directors Emma Higham and Tashi Gore of their work, which is the culmination of a two-year research process.
Robb Rutledge, advisor on the production, is the scientist who originally came up with the equation to predict happiness, something he tells HuffPostUK that involves "gambling, risk, potential reward".
He explains: "When we ask people how they're feeling at each stage of our experiments, we have to weigh up what's happened to them recently, and take into account expectations and potential reward.
"When we all feel actual happiness, it depends not on how things are going objectively, but whether things are going better or worse than we previously expected."
For the producers of the show, it was important to focus the show on the young participants and see life through their eyes. It seems the areas that most affect the happiness of young people in the UK are education, opportunities, expectations, consumerism, love, politics and power.
Were any universal truths uncovered from this marriage of arts and science?
"Music, finding your flow, being lost in something bigger than yourself, doing something for someone else, a community, a collective moment/action/experience – these were all things which came up repeatedly within our process," say Emma Higham and Tashi Gore.
"These are really difficult questions," confirms Robb Routledge, "ones that people have been asking for thousands of years. Art and science have a lot in common, they just use different methods."
Robb is convinced that audience-goers will be stimulated to think about what happiness really means to them. "There can be a lot of demands on people, especially youngsters," he says, "and everybody has to decide for themselves what happiness really means to them.
"There are obviously lots of 'happiness guarantees' that turn up in top-20 lists, including getting more sleep, enjoying more family time, eating well, meditating... but we can't assume this is true across the board.
"People need to pay attention to their own happiness, and feel free to cherry-pick from these lists. But it's great that governments are finally joining in the conversation."
Isn't there an awful lot of pressure these days to be as happy as everyone else claims to be on Facebook and other bragging forms of social media?
Robb agrees wholeheartedly. "It may be helpful for people to think of happiness less as a moment to moment thing, and more of a tool for them to understand themselves better.
"People shouldn’t worry about whether they’re happy or not, if you’re happy all the time, you can’t tell whether the restaurant you went to was good, or the movie was bad. It's much better for your emotions to be varied to give you some sense of perspective."
The Happiness Project is at the Roundhouse 3-14 November. For tickets: www.roundhouse.org.uk 0300 6789 222