I liked Dimitri. He was probably my favorite of the whole Hail Mary gang. But who knows what he’s up to now? Heck, Russia and the United States may be at war. Or they may be allies in a war. I have no idea.

I climb the ladder to the control room. I sit in the pilot’s seat and bring up the Nav panel. I really shouldn’t do this, but it’s become a bit of a ritual. I shut off the spin drives and coast. Gravity immediately disappears, but I hardly notice. I’m used to it.

With the spin drives off, I can safely use the Petrovascope. I scan around in space for a bit—I know where to look. I quickly find it. The little dot of Petrova-frequency light. The Blip-A’s engines. If I were within a hundred kilometers of that light, my entire ship would be vaporized.

I’m on one side of the system and he’s on the other. Heck, even Tau Ceti itself just looks like a lightbulb in the distance. But I can still clearly make out the Blip-A’s engine flare. Using light as a propellant releases a simply absurd amount of power.

Maybe that’s something we could use in the future. Maybe Earth and Erid could communicate with massive releases of Petrova light thanks to Astrophage. I wonder how much it would take to make a flash visible from 40 Eridani. We could talk in Morse code or something. They have a copy of Wikipedia now. They’d work out what we’re up to when they saw the flashes.

Still, our “conversation” would be slow. 40 Eridani is sixteen light-years away from Earth. So if we sent a message like “Hey, how ya doin’?” it would be thirty-two years before we got their reply.

I stare at the little point of light on the screen and sigh. I’ll be able to track him for quite a while. I know where his ship will be at any given moment. He’ll use the exact flight plan I gave him. He trusts my science as much as I trust his engineering. But after a few months, the Petrovascope won’t be able to see the light anymore. Not because the light is too dim—it’s a very sensitive instrument. It won’t be able to see him because our relative velocities will cause a red-shift in the light coming off his drives. It won’t be the Petrova wavelength anymore when it gets to me.

What? Would I do a ridiculous amount of relativistic math to calculate our relative velocity at any given moment as perceived by my inertial reference frame and then do Lorentz transformations to figure out when the light from his engines will drop out of the Petrovascope’s perception range? Just so I know how much longer I can see my friend in the distance? Wouldn’t that be kind of pathetic?