Isaac Asimov - Fantastic Voyage II - Destination Brain

He attempted to will himself to relax. He tried to let himself droop, but that required more than an effort of will. It needed gravitational pull and there was none to speak of. He closed his eyes and slowed his breathing. He even tried humming, under his breath, the choral singing from Beethoven's Ninth Symphony.

Finally he felt himself forced into comment on the matter. "I'm sorry," he said. "I seem to be shaking."

Dezhnev snickered. "Aha! I wondered who would be the first to mention it."

Boranova said, "It's not you, Albert. We are all shaking slightly. It's the ship."

Morrison was at once elevated into fright. "Is something wrong with it?"

"No. It's just a matter of size. It's small enough to feel the effect of Brownian motion. You know what that is, don't you?"

It was a purely rhetorical question. Boranova would surely expect a high school student of physics to know what Brownian motion was, let alone Morrison, and yet Morrison found himself explaining it in his own mind - not in words, but as a flash of concept.

Every object suspended in a liquid is bombarded on all sides by the atoms or molecules of the liquid. These particles strike randomly and therefore unevenly, but the unevenness is so small compared to the total that it is unnoticeable and has no measurable effect. As an object grows smaller, however, the unevenness becomes greater among the smaller and smaller number of particles striking the object in a given time. The ship was small enough now to respond to the slight excesses of coillisions - first in one direction, then in another - randomly. It moved slightly in consequence, a random trembling.

Morrison said, "Yes, I should have thought of that. It will get worse if we continue to become smaller."

"Actually, it won't," said Boranova. "There will be other counteracting effects."

"I don't know of any," said Morrison, frowning.

"Nevertheless, there will be such effects."

"Leave it to the Equations," said Dezhnev in an affectedly pious tone. "The Equations know."

Morrison said, "I think this could make us seasick."

"It certainly would," said Boranova, "but there is a chemical treatment for that. We have been dosed with the same chemical that cosmonauts use against space sickness."

"Not I," said Morrison indignantly. "Not only haven't I been treated, I haven't even been forewarned."

"We told you as little as possible of the discomforts and dangers out of concern for your comfort, Albert. As for treatment, you consumed your dose with your breakfast. - How do you feel?"

Morrison, who had begun to feel a bit squeamish with all this talk about sickness, decided that he felt fine. Astonishing, he thought, the tyranny exerted over the body by the mind.

He said in a low voice, "Tolerable."

"Good," said Boranova, "because we are now in Academician Shapirov's bloodstream."

Morrison stared through the transparent wall of the ship.

Blood?

His first impulse was to expect redness. What else?

He peered out, squinting his eyes slightly, but could see nothing, even in the gleaming light of the ship. He might as well have been in a rowboat, drifting down the calm surface of a pond on a dark and cloudy night.

Morrison's thoughts suddenly veered. In the absolute sense, the light within the ship had the wavelength of gamma rays - and very hard gamma rays at that. Yet the wavelengths were the result of miniaturizing ordinary visible light and to the equally miniaturized retinas and optic lobes of the people within the ship they were still light rays and had the property of light rays.

Outside, just beyond the hull of the ship, where the miniaturization field ended, the miniaturized photons enlarged to ordinary light-wave photons and those that were reflected back to the ship were miniaturized again when the field boundary was crossed. The others might be accustomed to this paradox-ridden situation, but to Morrison the attempt to grasp the effect of a miniaturized bubble within a sea of normality was dizzying. Was the boundary visible, marking off the miniaturized from the normal? Was there a discontinuity somewhere?

Following his line of thought, he whispered to Kaliinin, who was bent over her instrument, "Sophia, when our light leaves the miniaturization field and expands, it must give off heat energy, and when it's reflected back into the ship it must absorb energy in order to be miniaturized and the energy must come from us. Am I right?"

"Perfectly, Albert," said Kaliinin without looking up. "Our use of light results in a small but steady loss of energy, but our motors can supply that. It is not a significant drain."

"And are we really in the bloodstream?"

"Never fear. We are. Natalya will probably dim the internal lights in a while and you'll see the outside more clearly then."

Almost as though that were a signal, Boranova said, "There! Now we can relax for a few moments." The lights dimmed.

At once, objects outside the ship came dimly into view. He could not make them out clearly yet, but they were immersed in something heterogeneous, something with objects floating in it, as would be true of blood.

Morrison stirred uneasily, straining at the constraint of his seat belt. He said, "But if we are in the bloodstream, which is at a temperature of thirty-seven degrees Celsius, we'll -"

"Our temperature is conditioned. We'll be quite comfortable," said Kaliinin. "Really, Albert, we've thought of these things."

"Perhaps you have," said Morrison, slightly offended, "but I haven't been privy to those thoughts, have I? How can you condition the temperature when you don't have a cold sink?"

"We don't have one here, but there's outer space, isn't there? The microfusion motors give off a thin drizzle of subatomic particles which, under miniaturized conditions, have a mass of very nearly zero. They therefore travel at virtually the speed of light, penetrating matter as easily as neutrinos do and carrying off energy with them. In less than a second they are in outer space, so that the effect is of transferring heat from within the ship into outer space and we keep cool. Do you see?"

"I see," muttered Morrison. It was ingenious - but perhaps obvious, after all, to those used to thinking in terms of miniaturization.

Morrison noticed that the controls of the ship, immediately under Dezhnev's hands, were luminous, as were the instruments before Kaliinin. He struggled to raise himself in his seat and managed to see a corner of the computer screen in front of Konev. It contained what Morrison thought might be a map of the circulatory system of the neck. For a moment, before his body ceased its fight against the webbing of the belt and he sank down into his seat again, he saw a small red dot on the screen, which, he deduced, was a device to mark the position of the ship in the left internal carotid artery.

He was panting a little from his effort and had to wait a few moments to regain control of his breath. The recess in which his own computer rested was illuminated and he shielded that bit of light from his face by raising his left hand. Then he looked out.

Far in the distance, Morrison could see something that looked like a wall, a barrier of some sort. It receded, then approached, then receded again, over and over, rhythmically. Automatically, he looked at his watch for a few seconds. It was clearly the pulsation of the arterial wall.

He said to Kaliinin in a low voice, "Obviously the passage of time is not affected by miniaturization. At least the pulsation of the heart is - just what it ought to be, even though I view it with miniaturized eyes and time it with a miniaturized watch."

It was Konev who answered. "Time isn't quantized apparently, or at least it isn't affected oy the miniaturization field, which may be the same thing. That's convenient. If we had to take a shifting time flow into account, things might become unbearably complicated."