Rocky and I talk about biology for hours. Both of us are intensely interested in how the other's body works. We'd be pretty lame scientists if we weren't.
Eridian physiology is, frankly, amazing.
Erid is so close to its star, the sheer amount of energy entering the biosphere is ridiculous. And Eridians, being at the top of the food chain, have a heck of a lot more energy to work with than human bodies do. How much more? They have sacs in their body that just hold ATP—the main energy-storage medium of DNA-based life. Usually it lives in cells, but they have so much they have to evolve more efficient storage for it.
We're talking absurd amounts of energy here. They pull oxygen off minerals to get metals. Eridians are, in effect, biological smelters.
Humans have hair, fingernails, tooth enamel, and other "dead" stuff on our bodies that serve critical purposes. Eridians take that concept to the ultimate extreme. Rocky's carapace is made of oxidized minerals. His bones are honeycombed metallic alloys. His blood is mostly liquid mercury. Even his nerves are inorganic silicates transmitting light-based impulses.
All told, Rocky only has a few kilograms of biological material. Single-celled organisms travel through the bloodstream, building up or repairing the body as needed. They also manage digestion and service the brain, which sits safely in the center of his carapace.
If bees evolved to make hives that could walk, and the queen was as intelligent as a human, that life-form would be similar to an Eridian. Except the Eridian's "bees" are single-celled organisms.
Eridian muscles are inorganic. They're made of porous, sponge-like material sealed in flexible sacs. The majority of the body's water is tied up in those sacs. And the atmospheric pressure is so high, the 210°C water is still a liquid.
They have two separate circulatory systems: the "ambient" system and the "hot" system. The ambient blood is 210 degrees Celsius. But the hot blood is kept at 305 degrees, which is hot enough to boil water even at Erid's air pressure. Both circulatory systems have blood vessels that expand or contract around the muscles as needed to set their temperature. Want to expand? Make it hot. Want to contract? Make it cold.
In short: Eridians are steam-powered.
Because of this, the ambient circulatory system ends up as the heat sinks when muscles are cooled. It constantly needs to be cooled back down to normal temperature, hence the radiator. Rocky "breathes" in a sense, but only to pass outside ammonia across capillaries in a radiator-like organ in the top of his carapace. Five slits at the top allow the air in and out, but at no point does any of it enter his bloodstream.
While Eridians don't "breathe," they do still use oxygen. They're just much more self-contained than a human body. They have plant-like cells and animal-like cells inside. Oxygen to CO2, CO2 to oxygen, back and forth, always kept in balance. Rocky's body is a little biosphere. All it needs is energy via food and airflow to dump heat.
Meanwhile, the hot blood is too hot for any biological material to survive inside—it boils the water inside. This is handy for sterilizing incoming food of pathogens, by the way.
But in order for his worker cells to service any part of the hot-blood system, the system has to be cooled to ambient levels. And when that happens, the Eridian can't use muscles at all. And that's why Eridians sleep.
They don't "sleep" like a human does. They're legitimately paralyzed. And the brain, also being maintained, has no conscious function during that period. A sleeping Eridian can't wake up.
That's why they keep an eye on each other when they sleep. Someone has to keep you safe. Probably dates back to caveman (cave-Eridian?) days, and now it's just a social norm.
As amazed as I am at all that, to Rocky it's a boring topic. Meanwhile, he's utterly shocked and amazed by humanity.
"You hear light, question?" Rocky says. (He puts a little quaver on the first note of his sentence when he's surprised or impressed.)
"Yes. I hear light."
While we chat, he uses his many hands to assemble some complicated-looking piece of equipment. It's almost as big as he is. I recognize several parts on it as things he's been repairing these past few days. He can hold a conversation and work on delicate machinery at the same time. I think Eridians are much better at doing multiple tasks than humans are.
"How, question?" he asks. "How can you hear light, question?"
I point to my eyes. "These are special body parts that focus and detect light. They send the information to my brain."
"Light gives you information, question? Enough information to understand room, question?"
"Yes. Light gives information to humans like sound gives information to Eridians."
A thought occurs to him. He stops working on his device entirely. "You hear light from space, question? You hear stars, planets, asteroids, question?"
"Yes."
"Amaze. What about sound, question? You can hear sound."
I point to my ears. "I hear sound with these. How do you hear sound?"
He gestures all over his carapace and arms. "Everywhere. Tiny receptors on outer shell. All report back to brain. Like touch."
So his whole body is a microphone. His brain must be doing some serious processing. It has to know the exact position of the body, sense the time difference between sound hitting different parts of it…man, that's interesting. But hey, my brain gives me an entire 3-D model of my surroundings just from two eyeballs. Sensory input is really impressive across the board.
"I can't hear as well as you," I say. "Without light, I can't understand the room. I can hear you talk, but no more."
He points to the divider. "This is wall."
"This is a special wall. Light passes through this wall."
"Amaze. I give you many choices for wall when first build. You choose this because light pass through, question?"
It seems like so long ago—back when the divider was a mosaic of hexagons of different textures and colors. I'd picked the clear one, of course.
"Yes. I chose this because light passes through."
"Amaze. I gave choices for different ♫♩♪♫ of sound. Never thought of light."
I glance at the laptop to check what that mystery word was. I almost never have to look at the laptop now. Still, once in a while there's a chord I just don't remember. The computer reports that word was "qualities." Okay, I can't fault myself for not knowing it. That one doesn't come up very often.
"Just good luck," I say.
"Good luck," he agrees. He makes a few more adjustments to the device, puts his tools back in his bandolier, then says, "I am done."
"What is it?"
"Device keeps me alive in small room." He looks happy. I think. He's holding his carapace just a little higher than usual. "Wait."
He disappears back into his ship, leaving the device behind. He returns with several plates of transparent xenonite. Each plate is a pentagon about a centimeter thick and a foot across. I hate myself for thinking in hybrid units like that. But that's what my brain came up with.
"I make room now," he says.
He assembles the pentagons edge to edge, using some kind of thick liquid glue from a tube to hold them together. Soon, he has two halves of a dodecahedron assembled. He holds them toward me proudly and places them together. "Room."
The "room" is a geodesic sphere made of pentagons. The total diameter is about a meter. Easily big enough to contain Rocky.
"What's the purpose of that room?" I ask.
"Room and device keep me alive in you ship."
I raise my eyebrows. "You're coming into my ship?"
"Want to see human technology. Is allowed, question?"
"Yes! Allowed! What do you want to see?"
"Everything! Human science better than Eridian science." He points to the laptop floating beside me. "Machine that think. Eridians no have that." He points to my toolkit. "Many machines there Eridians no have."
"Yes. Come look at anything you want!" I point to the small airlock drawer in the divider wall. "How will you get it through that?"
"You leave tunnel. I make new divider wall. Bigger airlock."
He pulls the completed device—which I now realize is a life-support system—onto his carapace and straps it on. It covers the radiator slits at the top of his carapace.
"Is that blocking your radiator? Isn't that dangerous?"
"No. This make hot air into cold air," he says.
Air conditioning. Not what I think of when I see a species that lives comfortably at over 200 degrees Celsius. But we all have our tolerances.
He seals the globe around himself with glue. "I test."
He just floats there for a minute. Then, he says, "Works! Happy!"
"Great!" I say. "How does it work, though? Where does the heat go?"
"Easy," he says. He taps one small part of the device. "Astrophage here. Astrophage take all heat hotter than ninety-six degrees."
Ah, right. To humans, Astrophage is hot. To Eridians, it's quite cold. And it's the perfect air-conditioning medium. All Rocky has to do is run the air over some Astrophage-filled cooling fins or something.
"Clever," I say.
"Thank. You leave now. I make large airlock for tunnel."
"Yes yes yes!" I say.
I collect all my belongings in the tunnel, including the mattress clamped to the wall, and stuff them into the control room, then go into the control room myself and seal both airlock doors.
I spend the next hour tidying up. I wasn't expecting company.
It's been a few hours. But I just have to know. How does he modify the tunnel?
He needs massive atmospheric pressure to stay alive. My hull can't handle that. And he can't handle being in a vacuum. So how does he make modifications?
I hear clinks and clanks from the other side of the airlock. This time I'm going to find out!
I enter the airlock and look through the porthole. The Blip-A's hull robot has removed the old tunnel and is installing a new one.
Oh. Well. That's anticlimactic.
The old tunnel drifts off into space—its use is at an end, apparently. The robot places the new tunnel in position and administers xenonite glue along the edge of the Blip-A's hull.
How did Eridians pilot a ship that traveled near the speed of light without using computers? Dead reckoning? They're pretty good at doing math in their heads. Maybe they never needed to invent computers. But still. No matter how good they are at math, there are limits.
The clunking stops. I peek out the window again. The tunnel has been fully installed.
It looks like the previous tunnel, except it has a much larger airlock section. Pretty much the entire divider wall is a cabinet large enough to hold Rocky with room to spare. It is not, however, large enough to hold me. I guess I won't be visiting the Blip-A anytime soon.
"Hmph," I say. I try not to let it bother me, but come on. He gets to see an alien spaceship. How come I don't get to see one?
Rocky's side of the tunnel no longer has the network of gripping bars. Instead, there is a metal stripe running along the long axis of the tunnel. It extends into the divider airlock and further into my side of the tunnel. It leads right up to my airlock door.
Opposite the metal stripe is what looks like a pipe.