Ernest Rutherford always gets quite a few letters from bright-eyed young students asking him to be their doctoral advisor. He can't please everyone, so he declines most of the requests.
Lately, though, he's been thinking about getting a few more students. Nobody wanted to follow him across the ocean to England, and the laboratory seems a little barren. He spends an afternoon with his small pile of neglected letters, weeding out the plainly incompetent ones and the secondhand Nobel glory seekers, and whittles down his list.
A month later, the Danish student with the slightly stilted English and the somewhat promising record of laboratory ingenuity shows up. "Hello, I'm Niels Bohr," he says, lanky and grinning.
Ernest discovers rather quickly that Niels has barely any idea of what atomic physics is. He gives Niels the paper that Thompson had written, along with two dozen others, and Niels reads them in a weekend.
"I'm inclined to agree with several of the authors. With all due respect to Professor Thompson, the stability issue seems like a very serious problem with the model, and I am not sure how to resolve it," he says, very seriously. Ernest rolls his eyes a little.
It's eight o'clock in the evening, and Ernest is about to leave for the day, when he sees Niels stumble out of the dark room they use for the alpha particle scattering observations. "Where's Hans?" he asks Niels.
"He's gone home. I just wanted to finish for this angle," Niels replies, rubbing his eyes and looking around, disoriented from the light. "I, well. I've been thinking about how to make the measurement more automatic. It seems rather, I don't know. Less efficient than it could be."
Ernest sighs. He would let it slide, but Niels had had a rather uppity expression when Ernest had first shown him the apparatus, and Ernest certainly couldn't have his graduate students getting any ideas. "Do you have a proposal, or do you simply think that the measurement process is beneath you?"
"Oh, no, I don't think anything of that sort," Niels says. He looks genuinely affronted. "I just thought that we might be able to improve the accuracy, too, if we---"
"Well, have you talked to Hans about it?"
"I was planning to. I thought I'd ask you first."
Ernest sighs again. Niels could be a first-class headache. "Niels, surely you don't expect me to be the audience for each foolish idea that comes into your head. And surely you don't expect that you are the first man in the laboratory to have thought about such a thing. Talk to Hans." After a moment, he adds, "Although it would be a useful thing to have, if you manage to come up with something." Niels still needed a dissertation topic, after all.
"Alright," Niels says, smiling. "It was just an idea. Are you going home, professor?"
"Yes," Ernest says crossly, and leaves.
A few days later, Hans Geiger comes to him. "That student of yours has a few good ideas for the alpha particle counter," he says.
They begin to work on it. Niels makes a rather clever refinement of the sensitivity, but mostly just chatters too much. Ernest and Hans do most of the work. Eventually, Niels is relegated to the dark room for a few weeks along with one of the undergraduates, measuring radium emission rates over several orders of magnitude so they can calibrate the counter.
On another late night, after several months of work, they flip the lights on in the dark room and set up the radiation counter.
"Here we go," Ernest says, and turns it on. It's been thoroughly tested, of course, but Niels still grins when the click-click-click sound begins. Ernest thumps him on the back. "You'll never have to squint at a detector in a dark room ever again. Congratulations."
"It's brilliant," Niels says rather eagerly. "I, uh. I meant the portions that you did. And Hans. I hardly did anything at all."
"You mustn't be afraid to give yourself due credit, though it is hardly brilliant. Why don't you start repeating the measurements you've already made so we can confirm that the counter is working properly?" Niels starts moving toward the apparatus. "Don't be absurd, I meant tomorrow," Ernest says.
Another paper completed. He expects Niels to be occupied for the entire week with the drudgery of measuring the backscattering from metal. "For god's sake, don't be so upset. At least you don't have to sit in the dark anymore," he'd said to Niels, after Niels had made the slightest hint of an incredulous pout. What Ernest hadn't expected was Niels bursting into his office without knocking, waving around the notebook he's clutching.
"This is ridiculous," he says after looking at the data. "Did you set up the collimator correctly? Do it again."
Niels does it several times. Then Hans does it, then Ernest himself. "At least I don't have to worry about a dissertation topic anymore," Niels jokes. The alpha particles are bouncing back violently in every direction. It's a miracle.
They go out to a pub to celebrate, just the two of them, since Hans is off visiting family. Over a few pints, they work out the scattering cross-sections for a small, positively charged sphere. "It's still off by at least ten orders of magnitude," Ernest says.
Niels studies the napkin they'd been writing on. "You dropped a factor here," he says.
"Ah." Ernest attempts to work it out, but notices another factor elsewhere. "I don't think our inebriated state is aiding our calculations."
"I can do it!" Niels says. He scribbles on the napkin for a few minutes. "Maybe not," he concedes. "I'm rather tired, is all. Are you headed home after this?"
"Don't get any ideas, Niels," Ernest says. He is not unobservant. He's a physicist, after all.
"Of course not, professor."
Ernest works out the cross-sections and the maximum nuclear size in a few days.
"It's brilliant," Niels says. "Although I confess that I'm again concerned about the issue of stability."
"Oh, be quiet for now," Ernest says. "Actually, why don't you work on that?"