'The polar bears are the big problem. They're wonderful killing machines. They're clever, and they're especially dangerous when they're hungry.'
'Talking of which,' Stefi said. She waved the plastic bag and disappeared.
Romella flicked through the copy of the 1942 diary. 'There's some gobbledegook in here. Maybe you can make sense of it.'
Petrosian's diary, Wednesday, 28 July 1942
Our much-promised, and badly needed, long weekend.
Collected Kitty early. A joy to see her so happy. She was wearing a long green skirt and a sweater, and the Indian ear-rings I gave her. Loaded up the wagon with camping gear, but about half the car taken up with her easels and canvasses and other painting stuff. Guess what she'll be doing.
Took off eight a.m. and headed west. It was interesting to see the cacti getting smaller as we got higher and then the trees starting to appear and get bigger. Spent a couple of hours in the Petrified Forest and then on to Flagstaff. Nice town, clear air after the furnace heat of Los Alamos. Lots of pine trees around. Found a picnic place and devoured salad sandwiches and lemonade. Sky blue, air warm, and impossible to believe there's a war on. Then turned north and took a long straight road to the south rim of the Grand Canyon. It was dark by the time we got there.
Couldn't afford the restaurant prices in Grand Canyon village so decided we'd have a barbecue, which would be more fun anyway. Went to local store and bought hickory chips, charcoal, matches, firelighter, barbecue skewers, tin plates, mugs, coffee, sugar, milk, two bottles of red wine, T-bone steaks, barbecue sauces, cutlery, salt, pepper and chillies. Worked out twice as expensive as a dinner but who cares! Had a super time. Tried my party trick (reciting π to thirty decimal places). Kitty made me keep repeating it as the wine bottle went down. Think I passed the test.
Then the funny phone call. It makes me wonder how the hell they found me because I didn't know myself we were even going to be in Arizona, never mind the Grand Canyon, south rim. Went back to the store for toiletries and the phone was ringing as I entered. The storekeeper says are you Mister Miller — my code name when I travel — and I say yes. Unbelievable!! It's Oppie. Wants me to go to some lakeside cabin near a place called Escanaba, which apparently is on Lake Michigan. Over a thousand miles away. Wants me there tomorrow as a matter of 'supreme urgency'. I tell him I'm drunk and I'm here with Kitty, but he says dump her and make it anyway.
Got lost on the way back to the tent and wandered around the forest in the dark with visions of dropping into the canyon. Furious row. She can't believe I didn't phone in. Asked her if she'd run me to Flagstaff in the morning and could I borrow the train fare and she nearly hit me.
Thursday, 29 July 1942
I'll remember this day as long as I live.
I slept in the wagon, Kitty took the tent. I love Kitty to distraction and it hurts to have us quarrel. I can't blame her but at the same time can't tell her about the project.
Woke up about six. A racoon was heading for the remains of our barbecue, stopping to go up on its hind legs now and then. Ran off when I went to waken Kitty. Packed up, then zero conversation all the way to Flagstaff. Asked her to stay until Saturday and I'd try to get back and we'd still get our weekend but she took off the earrings and said, 'Give them to your Lake Michigan broad.' Felt sick.
Got to the cottage, which it turns out is being rented by Arthur Compton, also on holiday. We took a car down to a quiet beach overlooking the lake, and there I listened to Oppie's story.
Teller has been calculating the temperature build-up in the fission reaction. He finds that the heat will ignite the atmosphere and maybe even the oceans.
Arthur and Oppie both devastated. Compton says it's better to accept Nazi slavery than take the slightest chance that atom bombs could explode the air or the sea. The gadget must never be made.
Friday, 30 July 1942
Exhausted, having worked overnight on Teller's calculations. He thinks a deuterium/nitrogen reaction will take place and, the air being eighty per cent nitrogen, that we have a massive problem:
C12(H,γ)N13
N13(β)C13
C13(H,γ)N14
N14(H,γ)O15
015(β)N15
N15(H, He4)C12
So at fission temperatures two hydrogens combine with carbon to give a burst of gamma rays, the atmospheric nitrogen combines with the hydrogen in water vapour to create oxygen 15 and more gamma radiation, carrying a thumping great 7.4 Mev of energy. The O15 isotope is unstable and beta-decays to heavy nitrogen N15 in 82 seconds. A neutrino carries the energy from this clean out of the Galaxy so we forget it. But then the heavy nitrogen so created interacts with more hydrogen. It disintegrates back to ordinary carbon, creating helium and a hefty 5 Mev. It's as if the Earth's atmosphere has been created just waiting for the nuclear match. The bottleneck is the long reaction time for combining two hydrogen atoms with a carbon one. The fireball would cool down too fast to pull it off. But Teller has a trick up his sleeve. He says the two hydrogens are already there in the atmosphere's water: about one hydrogen atom in ten thousand is deuterium.
I suspect he's wrong. If my overnight sums are right the nuclear reaction rates need one hundred million degrees to be self-sustaining. I doubt if an atom bomb will yield more than fifty million degrees. So we're maybe on the right side of hell. Nice ethical dilemmas: (i) do we have the right to risk humanity on the correctness of our calculations? (ii) with a safety margin of only two, and given a straight choice, should we take a chance on burning the world or submit to Nazi slavery?
Mentally and physically worn out. But I can't complain. Nobody's shooting bullets at me.
Saturday, 31 July 1942
Refined the calculations with the help of better cross-sections. Chance now about three in a million. Compton says this is acceptable. Oppie asked who are we to decide on behalf of humanity what's an acceptable risk. I suggest we stick a notice in the local newspaper asking the public for their opinion. They don't think that's funny.
Flew back to Flagstaff on borrowed money, in desperation borrowed a pick-up from an incredibly kind woodcutter and hammered it all the way to the Grand Canyon. Kitty gone.
'What do you make of that?' Romella asked, rubbing her forearm. 'I'm freezing.'
'An irate girlfriend, and a near-miss on vaporizing the planet. Just another weekend.'
'This formula…' Romella asked.
'I haven't a clue.'
'If you say so.'
'If the sums had gone the other way…' Findhorn said. 'What's that?' He pointed to a smudged scribble.
She tilted the page and screwed up her nose in concentration. 'It says HMS Daring.'
'What has that got to do with anything?'
Romella shrugged. 'How would I know? It's probably nothing.'
'I agree. Probably nothing. Forget it.'
'Standard stuff, Freddie. Teller was discovering what's called the carbon-nitrogen cycle. It's what fuels hot stars, hotter than the Sun. But nothing on Earth can approach that sort of temperature.'
It was three o'clock in the morning and they were using oblique language. Archie had said it didn't matter as he was working anyway, and Findhorn didn't believe him even slightly.
Just a chat between friends.
About nuclear physics.
At three o'clock in the morning.
Nothing unusual about that. No eavesdropper would even notice.