The Early Asimov. Volume 2

A sudden rasping bur from below sent Prosser back from the railing.

'Get behind screen here,' he babbled. 'The twenty-millimeter field is going up. Bad radiation.'

The bur muted almost into silence, and the three walked out onto the passageway again. There was no apparent change, but Prosser shoved his hand out over the railing and said,, 'Feel!'

Orloff extended a cautious finger, gasped, and slapped out with the palm of his hand. It was like pushing against very soft sponge rubber or superresilient steel springs.

Birnam tried, too. 'That's better than anything we've done yet, isn't it?' He explained to Orloff, 'A twenty-millimeter screen is one that can hold an atmosphere of a pressure of twenty millimeters of mercury against a vacuum without appreciable leakage.'

The commissioner nodded, 'I see! You'd need a seven-hundred-sixty-millimeter screen to hold Earth's atmosphere then.'

'Yes! That would be a unit atmosphere screen. Well, Prosser, is this what got you excited?'

'This twenty-millimeter screen? Of course not. I can go up to two hundred fifty millimeters using the activated vanadium pentasulphide in the praseodymium breakdown. But it's not necessary. Technician would do it and blow up the place. Scientist checks on theory and goes slow,' He winked. 'We're hardening the field now. Watch!'

'Shall we get behind the screen?'

'Not necessary now. Radiation bad only at beginning.'

The burring waxed again, but not as loudly as before. Prosser shouted to the man at the control board, and a spreading wave of the hand was the only reply.

Then the control man waved a clenched fist and Prosser cried, 'We've passed fifty millimeters! Feel the field!'

Orloff extended his hand and poked it curiously. The sponge rubber had hardened! He tried to pinch it between finger and thumb so perfect was the illusion, but here the 'rubber' faded to unresisting air.

Prosser tch-tched impatiently. 'No resistance at right angles to force. Elementary mechanics, that is.'

The control man was gesturing again., 'Past seventy,' explained Prbsser. 'We're slowing down now. Critical point is 83-42.'

He hung over the railing and kicked out with his feet at the other two. 'Stay away! Dangerous!'

And then he yelled, 'Careful! The generator's bucking!'

The bur had risen to a hoarse maximum and the control man worked frantically at his switches. From within the quartz heart of the central atomic generator, the sullen red glow of the bursting atoms had brightened dangerously.

There was a break in the bur, a reverberant roar and a blast of air that threw Orloff hard against the wall.

Prosser dashed up. There was a cut over his eye. 'Hurt? No? Good, good! I was expecting something of the sort. Should have warned you. Let's go down. Where's Birnam?'

The tall Ganymedan picked himself up off the floor and brushed at his clothes. 'Here I am. What blew up?'

'Nothing blew up. Something buckled. Come on, down we go.' He dabbed at, his forehead with a handkerchief and led the way downward.

The control man removed his earphones as he approached and got off his stool. He looked tired, and his dirt-smeared face was greasy with perspiration.

'The damn thing started going at 82.8, boss. It almost caught me.'

'It did, did it?' growled Prosser. 'Within limits of error, isn't it? How's the generator? Hey, Stoddard!'

The technician addressed replied from his station at the generator, 'Tube 5 died. It'll take two days to replace.'

Prosser turned in satisfaction and said, 'It worked. Went exactly as presumed. Problem solved, gentlemen. Trouble over. Let's get back to rny office. I want to eat. And then I want to sleep.'

He did not refer to the subject again until once more behind the desk in his office, and then he spoke between huge bites of a liver-and-onion sandwich.

He addressed Birnam, 'Remember the work on space strain last June. It flopped, but we kept at it. Finch got a lead last week and I developed it. Everything fell into place. Slick as goose grease. Never saw anything like it.'

'Go ahead,' said Birnam, calmly. He knew Prosser sufficiently well to avoid showing impatience.

'You saw what happened. When a field tops 83.42 millimeters, it becomes unstable. Space won't stand the strain. It buckles and the field blows. Boom!'

Birnam's mouth dropped open and the arms of Orloff's chair creaked under sudden pressure. Silence for a while, and then Birnam said unsteadily, 'You mean force fields stronger than that are impossible?'

'They're possible. You can create them. But the denser they are, the more unstable they are. If I had turned on the two-hundred-and-fifty-millimeter field, it would have lasted one tenth of a second. Then, blooie! Would have blown up the Station! And myself! Technician would have done it. Scientist is warned by theory. Works carefully, the way I did. No harm done.'

Orloff tucked his monocle into his vest pocket and said tremulously, 'But if a force field is the same thing as interatomic forces, why is it that steel has such a strong interatomic binding force without bucking space? There's a flaw there.'

Prosser eyed him in annoyance. 'No flaw. Critical strength depends on number of generators. In steel, each atom is a force-field generator. That means about three hundred billion trillion generators for every ounce of matter. If we could use that many- As it is, one hundred generators would be the practical limit. That only raises the critical point to ninety-seven or thereabout.'

He got to his feet and continued with sudden fervor, 'No. Problem's over, I tell you. Absolutely impossible to create a force field capable of holding Earth's atmosphere for more than a hundredth of a second. Jovian atmosphere entirely out of question. Cold figures say that; backed by experiment. Space won't stand it!

'Let the Jovians do their damnedest. They can't get out! That's final! That's final! That's final!'

Orloff said, 'Mr. Secretary, can I send a spacegram anywhere in the Station? I want to tell Earth that I'm returning by the next ship and that the Jovian problem is liquidated - entirely and for good.'

Birnam said nothing, but the relief on his face as he shook hands with the colonial commissioner, transfigured the gaunt homeliness of it unbelievably.

And Dr. Prosser repeated, with a birdlike jerk of his head, 'That's final!'

Hal Tuttle looked up as Captain Everett of the spaceship Transparent, newest ship of the Comet Space Lines, entered his private observation room in the nose of the ship.

The captain said, 'A spacegram has just reached me from the home offices at Tucson. We're to pick up Colonel Commissioner Orloff at Jovopolis, Ganymede, and take him back to Earth.'

'Good. We haven't sighted any ships?'

'No, no! We're way off the regular space lanes. The first the System will know of us will be the landing of the Transparent on Ganymede. It will be the greatest thing in space travel since the first trip to the Moon.' His voice softened suddenly, 'What's wrong, Hal? This is your triumph, after all.'

Hal Tuttle looked up and out into the blackness of space. 'I suppose it is. Ten years of work, Sam. I lost an arm and an eye in that first explosion, but I don't regret them. It's the reaction that's got me. The problem is solved; my lifework is finished.'

'So is every steel-hulled ship in the System.'

Tuttle smiled. 'Yes. It's hard to realize, isn't it?' He gestured outward. 'You see the stars? Part of the time, there's nothing between them and us. It gives me a queazy feeling.' His voice brooded, 'Nine years I worked for nothing. I wasn't a theoretician, and never really knew where I was headed -just tried everything. I tried a little too hard and space wouldn't stand it. I paid an arm and an eye and started fresh.'

Captain Everett balled his fist and pounded the hull - the hull through which the stars shone unobstructed. There was the muffled thud of flesh striking an unyielding surface - but no response whatever from the invisible wall.