“I know. It’s very counterintuitive. But there’s a large neutrino burst every time they kill an Astrophage. They even took samples to the IceCube Neutrino Observatory and punctured them in the main detector pool. They got a massive number of hits. Astrophage can only contain neutrinos if it’s alive, and there’s a lot of them in there.”

“How does it make neutrinos?”

She flipped a few pages in the paper and pointed to another chart. “This is more your area than mine, but microbiologists have confirmed Astrophage has a lot of free hydrogen ions—raw protons with no electron—zipping around just inside the cell membrane.”

“Yeah, I remember reading about that. It was a group in Russia that found that out.”

She nodded. “CERN is pretty sure that, through a mechanism we don’t understand, when those protons collide at a high enough velocity, their kinetic energy is converted into two neutrinos with opposite momentum vectors.”

I leaned back, confused. “That is really odd. Mass usually doesn’t just ‘happen’ like that.”

She wiggled her hand. “Not quite true. Sometimes gamma rays, when they pass close to an atomic nucleus, will spontaneously become an electron and a positron. It’s called ‘pair production.’ So it’s not unheard-of. But we’ve never seen neutrinos created that way.”

“That’s kind of neat. I never got too deep into atomic physics. I’ve never heard of pair production before.”

“It’s a thing.”

“Okay.”

“Anyway,” she said, “there’s a lot of complicated stuff about neutrinos I won’t get into—there are different kinds and they can even change what kind they are. But the upshot is this: They’re an extremely small particle. Their mass is something like one twenty-billionth the mass of a proton.”

“Waaaaaait,” I said. “We know Astrophage is always 96.415 degrees Celsius. Temperature is just the velocity of particles inside. So we should be able to calcu—”

“Calculate the velocity of the particles inside,” she said. “Yes. We know the average velocity of the protons. And we know their mass, which means we know their kinetic energy. I know where you’re going with this and the answer is yes. It balances.”

“Wow!” I put my hand on my forehead. “That’s amazing!”

“Yes. It is.”

That was the answer to the long-asked question: Why is Astrophage’s critical temperature what it is? Why not hotter? Why not colder?

Astrophage makes neutrinos in pairs by slamming protons together. For the reaction to work, the protons need to collide with a higher kinetic energy than the mass energy of two neutrinos. If you work backward from the mass of a neutrino, you know the velocity those protons have to collide at. And when you know the velocity of particles in an object, you know its temperature. To have enough kinetic energy to make neutrinos, the protons have to be 96.415 degrees Celsius.