If you looked at a rock for several hours, and someone replaced it with a very similar, but slightly different rock, you would know.

Okay, so where is the rest of the crew? I’m alone because my crewmates didn’t make it. But Eridians have better technology, space-wise. Bigger ship, nigh-indestructible hull material. There has to be a crew in there.

Ah! I bet Rocky’s the captain! He puts himself at risk by talking to the scary alien. Everyone else stays back on the ship. That’s what Captain Kirk would do. So why not Captain Rocky?

Anyway, I have cool stuff I want to do and I’m impatient.

“Yo! Rocky!” I yell. “Come here!”

I listen for any sounds of movement. “Come on, man! Your entire ranged sensory input is sound—I bet you can hear a pin drop a mile away! You know I’m calling you! Move your…whatever serves as your butt! I want to talk!”

I wait and wait, but no Rocky.

My guess is I’m a pretty high priority to him. So whatever he’s doing must be really important. After all, he’s got a ship to deal with. He probably needs to eat and sleep. Well, he has to eat, anyway—all biological organisms need to get energy somehow. I don’t know if Eridians sleep.

Come to think of it…sleep might not be such a bad idea. Out of the past forty-eight hours I’ve had a two-hour nap and nothing else. Rocky’s clock is still there, wedged between a grab bar and the divider wall. It’s ticking away as normal. It’s interesting that his clock only has five digits. By my math, it’ll roll over back to ℓℓℓℓℓ every five hours or so. Maybe that’s the length of an Eridian day?

Speculate later. Sleep is the priority. I set up a spreadsheet on my Excel laptop to convert from Rocky time to mine and vice versa. I want to sleep for eight hours. I enter the current time on Rocky’s clock, which is IℓIVλ, and have the spreadsheet tell me what that clock will say eight hours from now. The answer: Iλ+VVλ.

I hurry back to the lab to pick up a bunch of Popsicle sticks and tape. Rocky can’t see ink, so I have to improvise.

I tape the sticks to the divider wall to let Rocky know when I’ll return: Iλ+VVλ. Fortunately, the symbols are mostly made of straight lines, so my little craft project should be good enough for him to read.

Interestingly, my return time has six digits. One more digit than Rocky’s clock shows. But I’m sure he’ll figure it out. If Rocky said “I’ll be back at thirty-seven o’clock,” I’d understand what he meant.

Before I hit the hay, I harvest a mini-camera from the lab’s vacuum chamber. It’s just a small wireless camera that talks to a portable LCD clipped to the chamber. I tape the camera up in the tunnel, pointed at the divider wall. I bring the readout screen with me to my bunk.

There. Now I have a baby-monitor setup in the tunnel. There’s no audio—the camera is for watching experiments, not chatting with people. But it’s better than nothing.

I tuck the bunk’s sheets and blankets in tight all around the oval mattress pad. I shimmy in between the tight bedding. This way I won’t just float around while I sleep.

My grand plans for communicating with Rocky will have to wait. I’m a little frustrated, but not for long. I conk out almost immediately.

Tap-tap-tap.

The sound barely penetrates my consciousness. It’s far away.

Tap-tap-tap.

I wake from a dreamless sleep. “Huh?”

Tap-tap-tap.

“Breakfast,” I mumble.

The mechanical arms reach into a compartment and pull out a packaged meal. It’s like Christmas every morning around here. I pull the top off and steam wafts out in all directions. There’s a breakfast burrito inside.

“Nice,” I say. “Coffee?”

“Preparing…”

I take a bite of the breakfast burrito. It’s good. All the food is good. I guess they figured if we’re going to die, we may as well eat good stuff.

“Coffee,” says the computer. A mechanical arm hands me a pouch with a pinch-straw in it. Like a Capri Sun for adults. Zero-g accommodations.

I let the burrito float nearby and take a sip of coffee. It’s delicious, of course. It even has just the right amount of cream and sugar. That’s a very personal preference that varies wildly from person to person.

Tap-tap-tap.

What is that, anyway?

I check the LCD screen taped near my bunk. Rocky is in the tunnel tapping on the divider wall.

“Computer! How long was I asleep?”

“Patient was unconscious for ten hours and seventeen minutes.”

“Oh crud!”

I wriggle out of my bedding and bounce up through the ship toward the control room. I carry the burrito and coffee with me because I’m starving.

I bounce into the tunnel. “Sorry! Sorry!”

Rocky taps the divider louder than before now that I’m here. He points to the Popsicle-stick numbers I taped to the divider and then to his clock. He balls one of his hands into a fist.

“I’m sorry!” I clasp my hands together as if praying. I don’t know what else to do. There’s no interplanetary symbol for supplication. I don’t know if he understands, but he unclenches his fist.

Maybe it was a mild admonishment. I mean, he could have made five fists, but he only made one.

Anyway, I kept him waiting over two hours. He’s understandably upset. Hopefully this next trick will make up for it.

I hold up a finger. He returns the gesture.

I grab my duct-taped laptops and launch the waveform-analysis software on one and Excel on the other. I press them against the tunnel wall and secure them there with tape.

I pull the Popsicle-stick numbers off the divider wall. They’re as good a place to start as any. I hold up the “I” and point to it. “One,” I say. “One.”

I point to my mouth, then back to the Eridian number. “One.” Then I point to Rocky.

He points to the “I” and says “♪.”

I pause the waveform analyzer and scroll back a few seconds. “There we go…” Rocky’s word for “one” is just two notes played at the same time. There are a bunch of harmonics and resonances in there, too, but the main frequency peaks are just two notes.

I type “one” into the spreadsheet on the other computer and note the relevant frequencies.

“Okay…” I return to the divider and hold up the “V” symbol. “Two,” I say.