The Black Star Passes

by Jr. John W. Campbell

  III

  Swiftly Arcot's sleek cruiser sped toward New York and the ArcotLaboratories. They had halted briefly at the headquarters ship of theEarth-Venus forces to report on their experience; and alone again, thethree scientists were on their way home.

  With their course set, Arcot spoke to the others. "Well, fellows, whatare your opinions on--what we've seen? Wade, you're a chemist--tell uswhat you think of the explosion of the ship, and of the strange color ofour molecular ray in their air."

  Wade shook his head doubtfully. "I've been trying to figure it out, andI can't quite believe my results. Still, I can't see any otherexplanation. That reddish glow looked like hydrogen ions in the air. Theatmosphere was certainly combustible when it met ours, which makes itimpossible for me to believe that their air contained any noticeableamount of oxygen, for anything above twenty per cent oxygen and the resthydrogen would be violently explosive. Apparently the gas had to mixliberally with our air to reach that proportion. That it didn't explodewhen ionized, showed the absence of hydro-oxygen mixture.

  "All the observed facts except one seem to point to an atmospherecomposed largely of hydrogen. That one--there are beings living in it! Ican understand how the Venerians might adapt to a different climate, butI can't see how anything approaching human life can live in anatmosphere like that."

  Arcot nodded. "I have come to similar conclusions. But I don't see toomuch objection to the thought of beings living in an atmosphere ofhydrogen. It's all a question of organic chemistry. Remember that ourbodies are just chemical furnaces. We take in fuel and oxidize it, usingthe heat as our source of power. The invaders live in an atmosphere ofhydrogen. They eat oxidizing fuels, and breathe a reducing atmosphere;they have the two fuel components together again, but in a way differentfrom our method. Evidently, it's just as effective. I'm sure that's thesecret of the whole thing."

  "Sounds fairly logical." Wade agreed. "But now I have a question foryou. Where under the sun did these beings come from?"

  Arcot's reply came slowly. "I've been wondering the same thing. And themore I wonder, the less I believe they did come from--under our sun.Let's eliminate all the solar planets--we can do that at one fell swoop.It's perfectly obvious that those ships are by no means the first crudeattempts of this race to fly through space. We're dealing with anadvanced technology. If they have had those ships even as far away asPluto, we should certainly have heard from them by now.

  "Hence, we've got to go out into interstellar space. You'll probablywant to ram some of my arguments down my throat--I know there is no starnear enough for the journey to be made in anything less than a couple ofgenerations by all that's logical; and they'd freeze in the interstellarcold doing it. There is no _known_ star close enough--but how aboutunknowns?"

  "What have they been doing with the star?" Morey snorted. "Hiding itbehind a sun-shade?"

  Arcot grinned. "Yes. A shade of old age. You know a sun can't radiateforever; eventually they die. And a dead sun would be quite black, I'msure."

  "And the planets that circle about them are apt to become a wee bit cooltoo, you know."

  "Agreed," said Arcot, "and we wouldn't be able to do much about it. Butgive these beings credit for a little higher order of intelligence. Wesaw machines in that space ship that certainly are beyond us! They areundoubtedly heating their planets with the same source of energy withwhich they are running their ships.

  "I believe I have confirmation of that statement in two things. They areabsolutely colorless; they don't even have an opaque white skin. Anyliving creature exposed to the rays of a sun, which is certain to emitsome chemical rays, is subject to coloration as a protection againstthose rays. The whites, who have always lived where sunlight is weakest,have developed a skin only slightly opaque. The Orientals, who live inmore tropical countries, where less clothes and more sun is the motto,have slightly darker skins. In the extreme tropics Nature has found itnecessary to use a regular blanket of color to stop the rays. Nowextrapolating the other way, were there no such rays, the people wouldbecome a pigmentless race. Since most proteins are rather translucent,at least when wet, they would appear much as these beings do. Remember,there are very few colored proteins. Hemoglobin, such as in our blood,and hemocyanin, like that in the blue blood of the Venerians, arepractically unique in that respect. For hydrogen absorption, I imaginethe blood of these creatures contains a fair proportion of some highlysaturated compound, which readily takes on the element, and gives it uplater.

  "But we can kick this around some more in the lab."

  Before starting for New York, Arcot had convinced the officer in chargethat it would be wise to destroy the more complete of the invaders'ships at once, lest one of them manage to escape. The fact that none ofthem had any rays in operation was easily explained; they would havebeen destroyed by the Patrol if they had made any show of weapons. Butthey might be getting some ready, to be used in possible escapeattempts. The scientists were through with their preliminaryinvestigations. And the dismembered sections would remain for study,anyway.

  The ships had finally been rayed apart, and when the three had left,their burning atmosphere had been sending mighty tongues of flame a mileor more into the air. The light gas of the alien atmosphere tended torise in a great globular cloud, a ball that quickly burned itself out.It had not taken long for the last of the machines to disintegrate underthe rays. There would be no more trouble from them, at any rate!

  Now Morey asked Arcot if he thought that they had learned all they couldfrom the ships; would it not have been wiser to save them, andinvestigate more fully later, taking a chance on stopping any suddenattack by surviving marauders by keeping a patrol of Air Guards there.

  To which Arcot replied, "I thought quite a bit before I suggested theirdestruction, and I conferred for a few moments with Forsyth, who's justabout tops in biology and bacteriology. He said that they had by nomeans learned as much as they wished to, but they'd been forced to leavein any event. Remember that pure hydrogen, the atmosphere we wereactually living in while on the ship, is quite as inert as pureoxygen--when alone. But the two get very rough when mixed together. Thelonger those ships lay there the more dangerously explosive they became.If we hadn't destroyed them, they would have wrecked themselves. I stillthink we followed the only logical course.

  "Dr. Forsyth mentioned the danger of disease. There's a remotepossibility that we might be susceptible to their germs. I don't believewe would be, for our chemical constitution is so vastly different. Forinstance, the Venerians and Terrestrians can visit each other withperfect freedom. The Venerians have diseases, and so do we, of course;but there are things in the blood of Venerians that are absolutelydeadly to any Terrestrian organism. We have a similar deadly effect onVenerian germs. It isn't immunity--it's simply that our respectiveconstitutions are so different that we don't need immunity. Similarly,Forsyth thinks we would be completely resistant to all diseases broughtby the invaders. However, it's safer to remove the danger, if any,first, and check afterward."

  The three men sped rapidly back to New York, flying nearly sixty milesabove the surface of the Earth, where there would be no interferingtraffic, till at length they were above the big city, and droppingswiftly in a vertical traffic lane.

  Shortly thereafter they settled lightly in the landing cradle at theArcot Laboratories. Arcot's father, and Morey's, were there, anxiouslyawaiting their return. The elder Arcot had for many years held thereputation of being the nation's greatest physicist, but recently he hadlost it--to his son. Morey Senior was the president and chiefstockholder in the Transcontinental Air Lines. The Arcots, father andson, had turned all their inventions over to their close friends, theMoreys. For many years the success of the great air lines had beendependent in large part on the inventions of the Arcots; these newdiscoveries enabled them to keep one step ahead of competition, and asthey also made the huge transport machines for other companies, theydrew tremendous profits from these mechanisms. The mutual interest,which had begun as a purely
financial relationship, had long sincebecome a close personal friendship.

  As Arcot stepped from his speedster, he called immediately to hisfather, telling of their find, the light-matter plate.

  "I'll need a handling machine to move it. I'll be right back." He ran tothe elevator and dropped quickly to the heavy machinery lab on the lowerfloor. In a short time he returned with a tractor-like machine equippedwith a small derrick, designed to get its power from the electric mains.He ran the machine over to the ship. The others looked up as they heardthe rumble and hum of its powerful motor. From the crane dangled astrong electro-magnet.

  "What's that for?" asked Wade, pointing to the magnet. "You don't expectthis to be magnetic, do you?"

  "Wait and see!" laughed Arcot, maneuvering the handling machine intoposition. One of the others made contact with the power line, and thecrane reached into the ship, lowering the magnet to the plate ofcrystal. Then Arcot turned the power into the lifting motor. The humrose swiftly in volume and pitch till the full load began to strain thecables. The motor whined with full power, the cables vibrating under thetension. The machine pulled steadily, until, to Arcot's surprise, therear end of the machine rose abruptly from the floor, tipping forward.

  "Well--it _was_ magnetic, but how did you know?" asked the surprisedWade. Since the ship was made of the Venerian metal, coronium, which wasonly slightly magnetic, the plate was obviously the magnet's only load.

  "Never mind. I'll tell you later. Get an I-beam, say about twenty feetlong, and see if you can't help lift that crazy mass. I think we oughtto manage it that way."

  And so it proved. With two of them straddling the I-beam, the leveragewas great enough to pull the plate out. Running it over to the elevator,they lowered the heavy mass, disconnected the cable, and rode down toArcot's laboratory. Again the I-beam and handling machine were broughtinto play, and the plate was unloaded from the car. The five mengathered around the amazing souvenir from another world.

  "I'm with Wade in wondering how you knew the plate was magnetic, son,"commented the elder Arcot. "I can accept your explanation that the stuffis a kind of matter made of light, but I know you too well to think itwas just a lucky guess. How did you know?"

  "It really was pretty much of a guess, Dad, though there was some logicbehind the thought. You ought to be able to trace down the idea! Howabout you, Morey?" Arcot smiled at his friend.

  "I've kept discreetly quiet," replied Morey, "feeling that in silence Icould not betray my ignorance, but since you ask me, I can guess too. Iseem to recall that light is affected by a powerful magnet, and I canimagine that that was the basis for your guess. It has been known formany years, as far back as Clerk Maxwell, that polarized light can berotated by a powerful magnet."

  "That's it! And now we may as well go over the whole story, and tell Dadand your father all that happened. Perhaps in the telling, we canstraighten out our own ideas a bit."

  For the next hour the three men talked, each telling his story, andtrying to explain the whys and wherefores of what he had seen. In theend all agreed on one point: if they were to fight this enemy, they_must_ have ships that could travel though space with speed to matchthat of the invaders, ships with a self-contained source of power.

  During a brief lull in the conversation, Morey commented rathersarcastically: "I wonder if Arcot will now kindly explain his famousinvisible light, or the lost star?" He was a bit nettled by his ownfailure to remember that a star could go black. "I can't see whatconnection this has with their sudden attack. If they were there, theymust have developed when the star was bright, and as a star requiresmillions of years to cool down, I can't see how they could suddenlyappear in space."

  Before answering, Arcot reached into a drawer of his desk and pulled outan old blackened briar pipe. Methodically he filled it, a thoughtfulfrown on his face; then carefully lighting it, he leaned back, puffingout a thin column of gray smoke.

  "Those creatures must have developed on their planets before the suncooled." He puffed slowly. "They are, then, a race millions of yearsold--or so I believe. I can't give any scientific reason for thisfeeling; it's merely a hunch. I just have a feeling that the invadersare old, older than our very planet! This little globe is just about twobillion years old. I feel that that race is so very ancient they maywell have counted the revolutions of our galaxy as, once every twenty orthirty million years, it swung about its center.

  "When I looked at those great machines, and those comparatively littlebeings as they handled their projectors, they seemed out of place. Why?"He shrugged. "Again, just a hunch, an impression." He paused again, andthe slow smoke drifted upward.

  "If I'm granted the premise that a black, dead star is approaching theSolar System, then my theorizing may seem more logical. You agree?" Thelisteners nodded and Arcot continued. "Well--I had an idea--and when Iwent downstairs for the handling machine, I called the LunarObservatory." He couldn't quite keep a note of triumph out of his voice."Gentlemen--some of the planets have been misbehaving! The outermostplanets, and even some of those closer to the sun have not been movingas they should. A celestial body of appreciable mass _is_ approachingthe System; though thus far nothing has been seen of the visitor!"

  A hubbub of excited comment followed this startling revelation. Arcotquieted them with an upraised hand. "The only reason you and the worldat large haven't heard about this as yet is the fact that theperturbation of the planets is so very slight that the astronomersfigured they might have made an error in calculation. They'rerechecking now for mistakes.

  "To get back to my visualization--It must have been many millions ofyears ago that life developed on the planets of the black star, a warmsun then, for it was much younger. It was probably rather dim as suns goeven its younger days. Remember, our own sun is well above average inbrilliance and heat radiation.

  "In those long-gone ages I can imagine a race much like ours developing,differing chemically, in their atmosphere of hydrogen; but the chemicalbody is not what makes the race, it's the thought process. They musthave developed, and then as their science grew, their sun waned. Dimmerand dimmer it became, until their planets could not maintain lifenaturally. Then they had to heat them artificially. There is no questionas to their source of power; they had to use the energy of matter--socalled atomic energy--for no other source would be great enough to dowhat had to be done. It is probable that their science had developedthis long before their great need arose.

  "With this must also have come the process of transmutation, and theprocess they use in driving their interstellar cruisers. I am sure thosemachines are driven by material energy.

  "But at last their star was black, a closed star, and their cold, blackplanets must circle a hot, black sun forever! They were trapped foreternity unless they found a way to escape to some other stellar system.They could not travel as fast as light, and they could escape only ifthey found some near-by solar system. Their star was dead--black. Let'scall it Nigra--the Black One--since like every other star it should havea name. Any objection?"

  There was none, so Arcot continued:

  "Now we come to an impossibly rare coincidence. That two suns in theirmotion should approach each other is beyond the point of logic. Thatboth suns have a retinue of planets approaches the height of theridiculous. Yet that is what is happening right now. And the Nigrans--ifthat's the correct term--have every intention of taking advantage ofthe coincidence. Since our sun has been visible to them for a long, longtime, and the approaching proximity of the suns evident, they had lotsof time to prepare.

  "I believe this expedition was just an exploratory one; and if they cansend such huge machines and so many of them, for mere exploration, I'msure they must have quite a fleet to fight with.

  "We know little about their weapons. They have that death ray, but it'snot quite as deadly as we might have feared, solely because our shipscould outmaneuver them. Next time, logically, they'll bring with them afleet of little ships, carried in the bellies of those giants, andthey'll be a r
eal enemy. We'll have to anticipate their moves and buildto circumvent them.

  "As for their ray, I believe I have an idea how it works. You're allfamiliar with the catalytic effects of light. Hydrogen and chlorine willstand very peacefully in the same jar for a long time, but let a stronglight fall on them, and they combine with terrific violence. This is thecatalytic effect of a vibration, a wave motion. Then there is such athing as negative catalysis. In a certain reaction, if a third elementor compound is introduced, all reaction is stopped. I believe that's theprinciple of the Nigran death ray; it's a catalyst that simply stops thechemical reactions of a living body, and these are so delicatelybalanced that the least resistance will upset them."

  Arcot halted, and sat puffing furiously for a moment. During hisdiscourse the pipe had died to an ember; with vigorous puffing he triedto restore it. At last he had it going and continued.

  "What other weapons they have we cannot say. The secret of invisibilitymust be very old to them. But we'll guard against the possibility byequipping our ships against it. The only reason the patrol ships aren'tequipped already is that invisibility is useless with modern criminals;they all know the secret and how to fight it."

  Morey interrupted with a question.

  "Arcot, it's obvious that we have to get out into space to meet theenemy--and we'll have to have freedom of movement there. How are wegoing to do it? I was wondering if we could use Wade's system of storingthe atomic hydrogen in solution. That yields about 100,000 calories forevery two grams, and since this is a method of storing heat energy, andyour molecular motion director is a method of converting heat intomechanical work with 100 per cent efficiency, why not use that? All weneed, really, is a method of storing heat energy for use while we're inspace."

  Arcot exhaled slowly before answering, watching the column of smokevanish into the air.

  "I thought of that, and I've been trying to think of other, and ifpossible, better, cheaper, and quicker ways of getting the necessarypower.

  "Let's eliminate the known sources one by one. The usual ones, the onesmen have been using for centuries, go out at once. The atomic hydrogenreaction stores more energy per gram than any other chemical reactionknown. Such things as the storage battery, the electro-static condenser,the induction coil, or plain heat storage, are worthless to us. The onlyother method of storing energy we know of is the method used by theKaxorians in driving their huge planes.

  "They use condensed light-energy. This is efficient to the ultimatemaximum, something no other method can hope to attain. Yet they needhuge reservoirs to store it. The result is still ineffective for ourpurpose; we want something we can put in a small space; we want tocondense the light still further. That will be the ideal form of energystorage, for then we will be able to release it directly as a heat ray,and so use it with utmost efficiency. I think we can absorb the releasedenergy in the usual cavity radiator."

  A queer little smile appeared on Arcot's face. "Remember--what we wantis light in a more condensed form, a form that is naturally stable, andthat does not need to be held in a bound state, but actually requiresurging to bring about the release of energy. For example--"

  A shout from Wade interrupted him. "That's really rare! _Whoo_--I haveto hand it to you! That takes all the prizes!" He laughed delightedly.In puzzled wonder Morey and the two older men looked at him, and atArcot who was grinning broadly now.

  "Well, I suppose it must be funny," Morey began, then hesitated. "Oh--Isee--say, that _is_ good!" He turned to his father. "I see now what he'sbeen driving at. It's been right here under our noses all the time.

  "The light-matter windows we found in the wrecked enemy ships containenough bound light-energy to run all the planes we could make in thenext ten years! We're going to have the enemy supply us with power wecan't get in any other way. I can't decide, Arcot, whether you deserve aprize for ingenuity, or whether we should receive booby-prizes for ourstupidity."

  Arcot Senior smiled at first, then looked dubiously at his son.

  "There's definitely plenty of the right kind of energy stored there--butas you suggested, the energy will need encouragement to break free. Anyideas?"

  "A couple. I don't know how they'll work, of course; but we can try."Arcot puffed at his pipe, serious now as he thought of the problemsahead.

  Wade interposed a question. "How do you suppose they condense that lightenergy in the first place, and, their sun being dead, whence all thelight? Back to the atom, I suppose."

  "You know as much as I do, of course, but I'm sure they must break upmatter for its energy. As for the condensation problem, I think I have apossible solution of that too--it's the key to the problem of release.There's a lot we don't know now--but we'll have a bigger store ofknowledge before this war is over--if we have anything at all!" he addedgrimly. "It's possible that man may lose knowledge, life, his planetsand sun--but there's still plenty of hope. We're not finished yet."

  "How do you think they got their energy loose?" asked

  Wade. "Do you think those big blocks of what appeared to be silver wereinvolved in the energy release?"

  "Yes, I do. Those blocks were probably designed to carry away the poweronce it was released. How the release was accomplished, though, I don'tknow. They couldn't use material apparatus to start their release ofmaterial energy; the material of the apparatus might 'catch fire' too.They had to have the disintegrating matter held apart from all othermatter. This was quite impossible, if you are going to get the energyaway by any method other than by the use of fields of force. I don'tthink that is the method. My guess is that a terrific current ofelectricity would accomplish it if anything would.

  "How then are we going to get the current to it? The wires will besubject to the same currents. Whatever they do to the matter involved,the currents will do to the apparatus--except in one case. If thatapparatus is made of _some other kind of matter_, then it wouldn't beaffected. The solution is obvious. Use some of the light-matter. Whatwill destroy light-matter, won't destroy electricity-matter, and whatwill destroy electricity-matter, won't disturb light-matter.

  "Do you remember the platform of light-metal, clear as crystal? It musthave been an insulating platform. What we started as our assumptions inthe case of the light-metal, we can now carry further. We said thatelectricity-metals carried electricity, so light-metals would carry orconduct light. Now we know that there is no substance which istransparent to light, that will carry electricity by metallicconduction. I mean, of course, that there is no substance transparent tolight, and at the same time capable of carrying electricity byelectronic transmission. True, we have things like NaCl solutions inordinary H_{2}O which will carry electricity, but here it's ionicconduction. Even glass will carry electricity very well when hot; whenred hot, glass will carry enough electricity to melt it very quickly.But again, glass is not a solid, but a viscous liquid, and it is againcarried by ionic conduction. Iron, copper, sodium, silver, lead--allmetals carry the current by means of electron drift through the solidmaterial. In such cases we can see that no transparent substanceconducts electricity.

  "Similarly, the reverse is true. No substance capable of carryingelectricity by metallic conduction is transparent. All are opaque, if inany thickness. Of course, gold is transparent when in leaf form--butwhen it's that thin it won't conduct very much! The peculiar conditionwe reach in the case of the invisible ship is different. There theeffects are brought about by the high frequency impressed. But you getmy point.

  "Do you remember those wires that we saw leading to that little box ofthe reflecting material? So perfectly reflecting it was that we didn'tsee it. We only saw where it must be; we saw the light it reflected.That was no doubt light-matter, a non-metal, and as such, non-conductiveto light. Like sulphur, an electric non-metal, it reflected the base ofwhich it was formed. Sulphur reflects the base of which it was formed.Sulphur reflects electricity and--in the crystalline form--passes light.This light-non-metal did the same sort of thing; it reflected light andpassed electricity. It
was a conductor.

  "Now we have the things we need, the matter to disintegrate, and thematter to hold the disintegrating material in. We have two differenttypes of matter. The rest is obvious--but decidedly not easy. They havedone it, though; and after the war is over, there should be many oftheir machines drifting about in space waiting to give up theirsecrets."

  Arcot Senior clapped his son on the back. "A fair foundation on which tostart, anyway. But I think it's time now that you got working on yourproblem; and since I'm officially retired, I'm going downstairs. Youknow I'm working in my lab on a method to increase the range and powerof your projector for the molecular motion field. Young Norris ishelping me, and he really has ideas. I'll show you our math later."

  The party broke up, the three younger men staying in their own labs, theolder men leaving.