By David Sillito
Arts correspondent, BBC News
A study claims that between the ages of 20 and 40 people lose about one friend every year.
Writer Theodore Zeldin, who has spent a lifetime studying friendships, wants to celebrate his 74th birthday with everyone - but only if you promise to have a proper conversation with a stranger.
Happy Birthday Dear.........errrr?
It is normally the one time you gather your all your friends together, but the academic Theodore Zeldin has planned a birthday party with a difference - he will know no-one.
"I normally don't have a birthday party but on this occasion everyone in the world can come, and they can have a conversation with someone they have never met," he says.
It's not friends he wants to see at the Louise Blouin Institute in London on Wednesday, it's strangers.
Professor Zeldin, the president of the Oxford Muse foundation, is a philosopher, historian and public speaker, and his most famous work is An Intimate History of Humanity.
He says the idea of friendship has, over the centuries, changed radically and has created a new pressing issue for humanity - the need for real conversation.
It is not new lands we need to be discovering but other people's thoughts.
"I think we have less and less time for conversation," he says.
Work, the decline of the family, cars and technology have, he says, all helped to isolate us and he feels it's his duty to try to make us all sit down and talk face to face about things that really matter.
"The great mystery of our time is what goes on in people's heads," he says.
So instead of food on the birthday menu there are topics for the conversation.
What have we rebelled against? When have we felt isolated? What have been our most difficult conversations?
It's not chit chat about Big Brother or the weather he wants but real dialogue.
And in societies such as Britain and America where the economy has shifted from manufacturing to services, communication is increasingly important but he feels many of us struggle to know how to have a real conversation, especially men.
"I'm amazed by the number of women in their 20s and 30s who come to me and say 'I just can't find men who are able to talk'. They do not talk about matters that are deep and emotional."
Of course there have been huge changes and improvements. The idea of friendship between men and women is, he says, largely a modern innovation.
There may be a shortage of men who know how to talk in a way that women find satisfying but it was far worse only a few years ago.
Behind all this is a sense that despite all the innovations in communications technology, we are actually speaking to fewer and fewer people in any meaningful way.
We can now spend our lives on mobile phones and computers feeling as though we are in contact but we are lost to those around us.
We are increasingly leading "bubble lives" in which we insulate ourselves from everyone apart from an ever diminishing circle of friends and acquaintances.
Professor Zeldin believes we only realise our problems when it's far too late.
At work a colleague will leave, who we think of as a friend but we will never see them again or even worse they will stay and then "stab you in the back" over a promotion.
Age is also a factor. In one piece of research it was calculated that we lose 1.2 friends a year between the ages of 20 and 40.
Our social lives wither under the pressure of work and family and it's often only after a divorce that we find how isolated we have become.
Modern life makes us suspicious and wary of strangers and one answer is perhaps conversation.
Of course the "Zeldin Method" is a rather exacting solution.
His menu of conversation usually takes around two hours to complete and took up to four when the strangers were French.
However, he claims 99% of the participants found it enlightening and enjoyable, and a reflection that while we may be talking all the time we avoid discussing things in any depth.
He is also not a fan of small talk and gossip. It is, he says, like apes grooming one another.
It helps bond us but it fails to help us understand one another.
Even in families that appear close there can be huge gulfs between the generations because everyone avoids talking about serious matters or what we really feel.
Mobile phones and computers do not solve this problem. The important thing is to sit down face to face and make time to talk.
It may seem uncomfortable and unnatural but, he feels, it's essential that we connect in a less superficial way, especially if it's with a person from a different culture.