Julie is a West End girl but she is no snob. Her dress came from Portslade, the underbelly of Brighton and Hove. That’s all I knew, it was all anyone knew except Betty, until the day. At the wedding feast Julie told her table something new. Her dressmaker had asked Julie if she had browsed any brides magazines. She had not. Did Julie want to see photos from her collection? She did not. What exactly did Julie have in mind? Julie said: ”…that moment when Diana Ross appears and opens up with I am in the middle of a Chain Reaction….?.

”Lord these affairs are hard upon the heart”.

So sighed Robert Oppenheimer as he waited, thin as a spectre, for the threshold event of our age. And ever since we have had to ask what could he have meant by these affairs? The gadget his team had built was without precedent. In one instant our species crossed over: it became fantastically powerful and fantastically vulnerable.

Absurdly it was these words that came to me my wedding eve. One billion marriages before me, one of them my own, and yet what the next day would bring appeared not just new to me but surely new to mankind. Like Oppenheimer I was very tense. I was approaching my threshold event.

The central issue that lay at the heart of the problems facing all groups at Los Alamos was essentially a familiar one in a new guise. It was the dusty and previously faintly uninteresting theory of diffusion. A scented woman enters a room, I fart amongst friends, what theory accounts for the movement of molecules to the nose? Only this time it was not molecules but the disintegration products of an atomic nucleus: the paths of free neutrons at varying velocities. Neutrons sometimes strike nuclei releasing more neutrons and energy. Under what conditions will a runaway process begin and what happens then? Diffusion underwent a kind of scrutiny that was without precedent in the annals of science because it was a theory that had suddenly to be pressed into practice. Everyone was tipped into a new way of working. Theoreticians had to abandon their symbols and work with numbers and shockingly some of these numbers actually had decimal points. Tools replaced theorems. Avenues of thought were valued for what they would achieve not for their logical and mathematical beauty. And at the heart of the T-2 division Richard Feynman, young and exuberant, delivered up a series of insights that struck even those who understood him best as near mystical. He was driving his team forward to a new understanding of criticality. He was a thinker developing his full formidable powers. He was also a man in love with a dying wife. By day Richard calculated, he manipulated the forms of pure logic, by night he penned love letters. Each weekend he hitched to see Arlene in the sanatorium down on the desert plain. He was powered by ambition and curiosity and love and desperation until Arlene succumbed to the Tuberculosis. The kindness of older men retired him from work and returned him to his family in New York City but Oppeneimer sent for him twenty days later. It was tight and Richard very nearly missed the bus but in the end he was there, with the older men, when the gadget exploded in the New Mexico desert. Richard did not know it but he was now ready for his best work, he was ready to make his signal contribution, he had crossed over.

Nowadays my enthusiasm for things sometimes takes me by surprise. One day a local bus had asked: ”How Brighton are you…..? and I found to my surprise I wanted to answer ”VERY”. My wedding was a chance to see how I was doing. The service was held in the Royal Pavilion (Indian on the outside, Chinese on the inside) and scored by Shania Twain. There was sunshine, there were painted ladies on stilts, there were jugglers and magicians. Everyone sat down in Havana to a fine lunch with fine wine. There were speeches and songs and dance.

The four bridesmaids wore J-Lo white faux fur jackets over black cocktail dresses and Julie, well she blew us all away. She was Glamour Girl: a shimmer of tall white satin, corseted and fish-tailed, wreathed in a four metre feather boa. She looked good all the way through. Deborah told Julie: I want to eat you.

Julie is a West End girl but she is no snob. Her dress came from Portslade, the underbelly of Brighton and Hove. That’s all I knew, it was all anyone knew, except Betty, until the day. At the wedding feast Julie told her table something new. Her dressmaker had asked Julie if she had browsed any brides magazines. She had not. Did Julie want to see photos from her collection? She did not. What exactly did Julie have in mind? Julie said: ”..that moment when Diana Ross enters and opens up with I am in the middle of a Chain Reaction… ”

Julie did not sit still for long, she worked the room (but it was not work for her) and got to sit and talk with everyone at her party. I also ventured forth but I returned more often to my place setting to say and do little. In my core my reaction was running fast and hot. I felt the energy rising until it threatened my person and I needed to chill. Above all I wanted to remain where Julie was and that was in the present…in Havana…in Brighton. On that day I wanted to cleave to the contours of every hour, to have my experience and not that of any other man, real or imagined.

And that for me – as it is not for Julie – is a challenge. My reaction to the world, to other people, is so often one of disappointment, of painful surprise. I see it now (as I did not see it before) but that doesn’t always prevent it. I srutt like a pomaded pontiff (but one terrified his influence is waning). How dare you impede me? How dare you not do as I ordain? I expect to be the most important and interesting person you have ever met. As this so rarely proved to be the case that I, for many years, experimented with keeping my world as small as possible (but it could not get small enough). So it was fascinating to experience a whole day when with Julie I was the most important and interesting person to a large number of people. I became the focus for good will, affection, praise and congratulations. And I found like good men before me it was wonderful and it was hard to take. For me kindness heals but first it hurts.

I made vows of betrothal in front of my children and at the biggest party of my life I stood up at a microphone and told one hundred people how I loved Julie. My children heard what they already knew: that I did not like to spend a night away from Julie but to do this I had chosen to spend almost all my nights away from them. I had said what was previously unsayable. My relationship with Julie had slid into secrecy and subterfuge but now we had surfaced (we had blown through the surface). My inclination is always to dissemble but I had just outed myself outrageously. When Jimmy completed the job, instancing my membership of a self-help group (I was a man in need of help?!) and that I had lost my job (all that spin spun off!!) I registered only mild surprise. The dog did not bark, there was no pain. I was stripped of all embarrassment, I was shame-free, I was inviolate.

I felt intensely vulnerable and intensely powerful. I felt raw and excited. I felt exposed but highly charged. I felt subject to a large force. In our serivce Charlie and Ed had read from His Dark Materials . In this tale Pullman re-writes an old fable. A child fulfils a prophesy and thus redeems us all, but this time the salvation is that the dead truly die. Lyra (unknowing but guided) achieves this by drawing to her a colossal explosion that rents the fabric between worlds. Last week I read that cosmologists ponder gamma ray bursts and I knew again what Feynman was getting at when he repeatedly urged that we all need use our imagination simply to comprehend what is. This is what cosmologists mean by a burst: the release in less than a second of a sum of energy at least one order of magnitude greater than the output of our sun over its lifetime of 10 billion years.

And in the cosmos these bursts happen every day…like weddings.

It was happening. In another dimension our celebration was going critical and something very big was about to go off. I’m in the middle of a chain reaction. Sam felt it, in fact he triggered it. The strong force was in play and he saw in his father a man surprised by joy, and then he was too he told us he was too, and then we all were. The air glowed blue, stripped of its electrons, and we experienced that which mediates the strong force between people . We all had tears.

I guess I enjoyed my party because my wife and I were the last out after the music guy had pulled the plug. An unforgettable movie lodged in my head is bringing up the rear of a bubbling caravan of kids and assorted family loaded with presents and cake. I saw that my airliner had ditched and I was on some sort of ramble with these good people (and others out of sight). Not only had I lost my plane I had appeared to have lost my captaincy. I was bringing up the rear with my cousin-in-law Guy, a bond trader, happily drunk, who kept repeating ”you have massively overachieved, man, massively overachieved”. I had lost my job the year before but I knew exactly what he meant. Actually I wasn’t really listening because my eyes were on Julie and Betty, chattering and clattering on their high heels, and I glimpsed what had really taken place this last year. Officially now aunt and niece Julie looked like no aunt on this earth and what was going on between them had the hue and colour of another relationship entirely. We promenaded to the taxi rank opposite the Pavilion where our day had begun and every head in every restaurant window swivelled and locked upon them. I saw mouths agape, broad smiles and two thumbs up. I reflected that five years ago I walked out of a house and a wife and three kids. That night I led a taxi convoy to my new house with my new wife and eighteen kids. I had yet to attempt the calculus and figure that one out.

In our kitchen, in our wedding attire, we read the house rules to the assembled kids and went off to the Granville hotel for conjugal sex, a curry and our bed. The kids brought down one book case (it was loose) but when we got back the next day they had hoovered and washed up and the house was otherwise OK. The next couple of days were about packing off kids and packing up our kitchen redy for the builders. But mostly we lit fires, watched movies, ordered take-aways and took calls. I did something else too. I checked a couple of texts and I googled to that baneful place, the middle of the twentieth century.

Julie and I had been shot so high it took days for our re-entry and in the end there was only one child left in the house and I was surprised but not surprised to see it was Sam. He was all teenager, playing Pro Evo Soccer, strumming his guitar, downloading Dylan. ”How’s your new best friend?” I joked to Julie. He and me and his stepmother came together at dinner not once but twice. It was utterly ordinary and very special.

In my head I venture back and forth but quite alot of the time I stumble around in the wardrobe between worlds. I fancy Julie hears my fumblings and when they become alarming she opens the door (before turning back to her cooking, to practicalities, to getting on with life). This time Julie said ”our Christmas card list will be a whole lot bigger this year”’. And blinking out of the wardrobe, festooned with clothes and hangers, I stand astounded because suddenly I see. Our world has hyper-inflated, her friends are my friends, my friends are her friends, our families our conjoined in places that are not yet clear. That feeling of enlargement, of power, is real. My coachDebbie has gone on and on about the process: first expansion then union. Of course: union. I have sneered at Christmas cards, but I won’t now. Now they seem precious, their little envelopes the carriers of filaments too frail for this world. I vow to do things differently because I get it now. But then the damn door swings shut and it is dark again.

I can make out it is pre-dawn, that it is 5:29 am on 16 July 1945 in a place already called the Journada del Muerto ( I didn’t make this up…you need all your imagination to understand what is…). I am here again but this time I have the answer to the riddle. Richard Feynman touched people and they would forever try to find words for the ineffable, for that which passed across from him to them and back again. Oppenheimer is intently regarding the younger man: brilliant, excited, devastated. Richard has so much ahead of him and Robert sees some of it. Robert educated in Europe and exquisite in his dress and science and scholarship would never learn to amalgamate his messy feelings. Robert has a fatal flaw that will bring him down but he is too clever and the moment is too rarefied for him to miss anything. He sees so much – for this man, for himself, for the future – but he cannot say it or prevent it. He sees the myriad ways we will disappoint each other and he knows, as Richard does not yet, that there are worse ways to do this than by dying. His gadget will end the war and it will splinter the group he has forged. Robert is fluent in Sanskrit, he is steeped in the perspective that our lives are coming together and parting. It is these affairs, these inescapable human affairs, that are so hard upon his heart.

Our of silence there came light sudden and shocking and as the light decayed though colours new to man Richard saw clouds in creation. The crack arrived after hundred and twenty seconds. In that interval of time something visited all the men in the hideout. They had been exposed to a powerful chain reaction and it had changed them completely.

Comically against physical type I cast my father as Oppenheimer. But I see the fit: remote, clinical, controlling, driven. Feynman is easy, he is Sam: mercurial, exhilarating, enchanting, maddening. I wonder where I fit in this shadow play. I have the younger man’s passion for a woman, I have the older man’s mileage (and more). I try to catch sight of myself but I am blurred, I am in motion. In my daily life since the wedding I have felt the shift, I am eccentric in my orbit, I swing about. I have been acted upon by a huge force and in another dimension I have accelerated (and one day – quite soon now – I will achieve escape velocity). The uncertainty principle applies here too. The more I know about my velocity the less certain I am of my position. It is only permissible to say I am somewhere in-between.