Ocean on Top

Chapter Twenty-four

I wasn’t through learning for the day, though. As I went through the huge valve and became visible from the tunnel outside, Marie’s voice met me. It had sharp edges, but otherwise it resembled a heavy club.

“Just where did you come up with the idea that these people weren’t getting oxygen through their lungs? If I killed Bert I’m not too sorry, but it’s your fault.”

Even I had had time to see that this question would be coming, but I’d had no chance to work out a very good answer. While the doctor had been working on Bert I’d been doing the same with my memory. It was evident enough that my theory of oxygen-food was out the window, but I still wasn’t able to find a better one.

All I could do was repeat the theory and my reasons for it. I also assured Marie that she hadn’t actually killed Bert. Somehow my reasoning didn’t look as airtight written out as it had felt when I was thinking it through in the first place — quite aside from the fact that it was now obviously wrong. In spite of this, Marie seemed to calm down as I wrote page after page, let her read each, and cleared it and went on to the next. The forced pauses may have helped.

I admit you convinced me before,” she said when I was done, “and I don’t see what the hole is myself. Joey, in the time you’ve been here have you found out enough to let you tell us what’s wrong with this notion?”

“I think so,” he wrote. He paused, and positioned himself outside the port so that Marie could read as he wrote. I swam to a spot a little further above and behind him, so I could do the same.

“Your big mistake was natural. You were quite right in observing that we aren’t breathing, as far as chest motions go. But in spite of that we are getting oxygen from this liquid. It’s wonderful stuff. You might regard its molecular structure as vaguely comparable to hemoglobin in that it binds oxygen molecules loosely to its surface. I don’t know just how many, but the number is large. It doesn’t have the porphyrin groups of hemoglobin; they went to great lengths to make it transparent to visible light. I couldn’t draw you its structural formula from memory. But I’ve seen it. It’s perfectly understandable.

“Now, think a minute. Liquid oxygen has a molecular concentration about four thousand times that of the gas we normally breathe. The reason we have to breathe is that diffusion, at sea-level concentrations, won’t get enough oxygen through your windpipe to keep an animal as large as a human being going. You can’t live in liquid oxygen, of course, because of temperature problems. However, in this liquid the concentration of almost-free oxygen is far, far higher than in the atmosphere — a long way short of what it is in LOX, but very high. That was another problem; while they were at it, they made the kernel of this molecule with a structure which would break down endothermically at temperatures above a few hundred degrees. A fire will tend to damp itself out, therefore. But that’s a side issue, as far as breathing is concerned.

“When molecules of the stuff give up their oxygen in your lungs, nearby molecules pass on more O2 to the ones which have lost it; others replenish those, and so on. It’s a bucket-brigade situation, but it’s described by just the same equations that you’d use for a diffusion problem. The rate of oxygen transport depends on the concentration difference between the inside of your lungs and outside, and on the area of the barrier through which the diffusion is taking place — in this case, the smallest cross-section area of your windpipe. In this case, the oxygen concentration around us is enough to keep us going by diffusion down our windpipes. I’m not sure about carbon-dioxide elimination, but I believe your theory is more nearly right there; it’s taken care of by binding into insoluble carbonates in the intestines and gotten rid of as solid waste. As I say, that seems a little funny to me, and I may have misunderstood what I read about it. I’m going to dig into the matter more when I have time. I’m no physiologist, but it’s fascinating reading, especially the history of its development.”

“But why such a fancy arrangement? A less efficient oxygen carrier would still work as long as you pumped fresh supplies into your lungs! That’s why we breathe, anyway!” Marie couldn’t have been thinking at the top of her form just then; even I could see the answer. I took the pad from Joey — in fact, he held it out to me, with a suspicion of a grin on his face — and started my own exposition.

“Pumping a liquid even denser than water through your windpipe would call for tremendous effort and probably dangerously high lung pressures. I tried it just after I made the change, and I know it hurts. I wouldn’t be surprised if you could rupture lung tissues that way. It’s a logical chain: fill body cavities with liquid so that outside pressure can be matched without serious volume change; then you can’t pump the liquid with your normal breathing equipment; so you have to give it a high enough free-oxygen concentration to diffuse an adequate supply down your throat. Simple once you see it. What’s the primary source of oxygen, though, Joey?”

“Just what you’d expect. Photosynthesis. That’s where most of the power produced here goes. About three-quarters of the oxygen comes from gene-tailored algae living at the interface between the ocean and the breathing liquid. The rest comes from the farm plants. Loss to the ocean is low because of the favorable partition ratio.”

I took the pad again.

“Well, at least I was right in guessing why laughing is dangerous, and why they do away with the coughing reflex; either action could rupture your lungs.”

“Of course,” agreed Joey. “I don’t claim to know the whole story yet — even Bert, who’s been here much longer, probably doesn’t. Remember, all we could learn about it was what we read, and that was only what happened to be lying around written in languages we knew. We weren’t told any of it by these people. Not only is it impossible to talk to them on such a level; I’m pretty sure most of them don’t know it either.

How many people at the surface, out of any given fifteen thousand, would be doctors or physiologists or even engineers?”

“That’s why they need us so badly,” I interjected. “Bert must have told you about that.”

“Who’d believe Bert?” snapped Marie — we’d been holding all our writings so she could read them, of course, even when they weren’t specifically meant for her. Joey took over the pad.

“You’d better. Whatever he said about these people being ready to do almost anything to keep technically skilled visitors down here is probably true. From what I’ve been able to make out in the last few weeks, unless some very extensive work is done on this installation quite soon, there’ll be twelve or fifteen thousand people migrating back to the surface and asking for their power ration in the next couple of decades.”

“How could they have the gall to do that?” Marie asked in scorn. “They’ve been down here all their lives, squandering power that should have gone into the world network and shared with the rest of us. They’re just like those old French aristocrats with their ‘Let ’em eat cake’ attitude — except the aristocrats would have been too proud to come begging the Jacquerie for crusts if their own wealth vanished.”

“That was my first reaction, too,” Joey wrote imperturbably. “I got myself pressured for the same reason Bert and you” — he nodded to me — “did; I planned to investigate as completely as possible and send up a report that would have the Board down here civilizing this place in a month. By the time I had enough data for a meaningful report, though, I realized it would be useless. The Board wouldn’t do anything about it.”

“That’s what Bert claimed,” I put in. “He said that such reports had been sent back before, decades ago, and that nothing had come of them.”

Joey reclaimed the pad.

“I never ran into any accounts of that sort. Bert and I wouldn’t have looked for just the same material, though, anyway. My point is that the Board can’t do anything about it.”

“Why not? Look at all the energy going to waste down here!” interjected Marie.

“Think again, girl. It’s not going to waste any more than the power used by natural plants on the surface for photosynthesis is going to waste — far less, in fact. It’s true that you can divide the power output of this installation by the local population figure and come up with a figure many times the normal per capita energy ration; but by far the greater part of that power goes into the lights. If you cut any significant percentage of the lights, you drop the photosynthesis rate to a level where there won’t be enough oxygen for the present population. If you cut the population by much, even the shaky maintenance that the outfit has now will degenerate, and, as I said, the place will have to shut down.

“You may criticize the decision the ancestors of these people made three or four generations ago. I agreed it was highly immoral by our standards. However, the current population is simply stuck with the consequences, and at least they’re not drawing from the planetary power net. They’re on their own, except intellectually. It seems quite in line with duty, to me, to stay here and help them. You’ll have to make your own choice.”

Marie was silent for half a minute or so, wrapped in thought. When she spoke again, it seemed to be a change of subject.

“Why did Bert lie to me? None of what you’ve been pointing out — which I can see makes sense — seems to call for it.”

Joey shrugged.

“I have no idea. Remember, he didn’t tell me you were here, much less anything else connected with you. I don’t know what he had on his mind.”

Joey’s eyes and Marie’s both swiveled toward me. After looking at my face for three or four seconds, the girl said, “All right, you know. Out with it.”

I reached for the pad which Joey was holding out to me, and made it fairly brief.

“He lied to you for the same reason I did. He didn’t care what you reported to the Board, but he didn’t want you ever to learn that Joey was alive. He wanted to get you back to the surface believing that Joey was just a memory and go back with you. I’d have done the same.”

Joey took the pad after Marie had read it, cleared off the message and wrote, “Thanks, Pal,” holding it so that I could see it but not Marie. Then he cleared it again immediately. If Marie noticed this, she made no comment. She may not have noticed, for my words had obviously jolted her.

“I see,” she said after at least two minutes of silence. “That puts a different light on the whole thing. He’s less obvious than some people, I must admit.” She paused for a few more seconds. Then, “Joey, I admit it’s your own private business; but are you willing to tell me exactly and truthfully why you decided to stay down here?”

A negative shake of the head was the answer.

“Or how long you plan to stay?”

Another negative.

“Or even whether you still regard yourself as a Board official?”

Still refusal. I was pretty sure that Joey didn’t really care whether Marie knew the answers to those questions, especially the first one; but, especially with the first one, he didn’t want to tell her himself. He was coming as close as his personality would let him to telling her to get out of his hair. Marie, as I have already said many times, is sharper than I am, in spite of one blind spot.

She looked at him speculatively after his third headshake, for several seconds. Then she suddenly turned to me.

“Are you staying?”

Naturally, I didn’t know. All I could do was throw the question back at her; she might be rougher on me than Joey had been on her, but I was ready for it — I hoped.

“Are you?” I wrote.

“ A shock wave, not quite painful, hit all of us; I don’t know whether she hit something with her fist or stamped her foot.

“Will you make your own mind up, just this once?” she snapped.

That was unjust, of course. I’m perfectly able to make decisions, and Marie knows it. She’s even admitted it. I just don’t like to make them when there’s a shortage of relevant information. She knew perfectly well what information I wanted, and why, too — she’d just been trying to get the same sort out of Joey for the same reason.

I made an honest effort to decide without reference to Marie, but I couldn’t do it.