stress that will set up the energy fields in the inter-space.”
'And you say there is another race that can tell us about this inter-space?”
'One other race I know of,' said the Engineer. 'There may be others, but I know only of this one. And it is hard to reach. Perhaps impossible to reach.”
'Listen,' said Gary, 'it is our only chance. We might as well fail in reaching them as waiting here for the energy to come and wipe us out. Let a couple of us try. The others may find something else before it is too late.
Caroline's hyperspheres might take care of the energy, but we can't be sure. And we have to be sure. The universe depends upon us being sure. We can't just shoot in the dark.
We have to know.”
'And if we find out,' said Herb, 'those guys over in the other universe can come over and help us hold the Hellhounds off while we rig up the stuff we have to have.”
'I'm afraid,' said Kingsley, 'we have to take the chance.”
'Chance,' said the Engineer. 'It's a whole lot more than chance. The place I have in mind may not even exist.”
'May not even exist?' asked Caroline and there was an edge of terror in her words.
'It is far away,' said the Engineer. 'Not far in space — perhaps even close to us in space. But far away in time.”
'In time?' asked Tommy. 'Some great civilization of the past?”
'No,' said the Engineer. 'A civilization of the future. A civilization which may never exist. One that may never come to be.”
'How do you know about it, then?' flared Gary.
'I followed its world line,' said the Engineer. 'And yet not its actual world line, but the world line that was to come. I traced it into the realm of probability. I followed it ahead in time, saw it as it is not yet, as it may never be. I saw the shadow of its probability.”
Gary's head reeled. What talk was this? Following of probable world lines.
Tracing the course of an empire before it had occurred! Seeing a place that might not ever exist. Talking of sending someone to a place that might never be!
But Caroline was talking now, her cool voice smooth and calm, but with a trace of excitement tinging the tenor of her words.
'You mean you used a geodesic tracer to follow the world line into probability. That you established the fact that in some future time a certain world may exist under such conditions as you saw. That barring unforeseen circumstances it will exist as you saw it, but that you cannot be certain it ever will exist, for the world line you traced could not take into account that factor of accident which might destroy the world or divert it from the path you charted, the path that it logically would have to take.”
'That is correct,' said the Engineer. 'Except for one thing. And that is that the world will exist as I saw it in some measure. For all probabilities must exist to some extent. But its existence might be so tenuous that we could never reach it… that for us, in hard, solid fact, it would have no real existence. In other words, we could not set foot upon it. For every real thing there are infinite probabilities, all existing, drawing some shadow of existence from the mere fact that they are probable or have been probable or will be probable. The stress and condition of circumstance selects one of these probabilities, makes it an actuality. But the others have an existence, just the same. An existence, perhaps, that we could not perceive.”
'But you did see this shadow of probability?' rumbled Kingsley.
'Yes,' said the Engineer, 'I saw it very plainly. So plainly that I am tempted to believe it may be an actuality in time to come. But of that I cannot be sure. As I said, it may not exist, may never exist — at least to an extent where we could reach it — where it would have any bearing on our lives.”
'There is a chance, though, that we could reach it?' asked Gary.
'There is a chance,' said the Engineer.
'Then,' said Herb, impatiently, 'what are we waiting for?”
'But,' said Gary, 'if the universe is destroyed, if we should fail and the universe be destroyed, would that probability still be there? Wouldn't the fact that you saw it prove that we will find some way to save the universe?”
'It proves nothing,' said the Engineer. 'Even were the universe destroyed, the probability would still exist, for the world could have been.
Destruction of the universe would be a factor of accident which would eliminate actuality and force all lines of probability to remain mere probability.”
'You mean,' breathed Caroline, 'that we could go to a world which exists only as a probable world line and get information there to save the universe — that even after the universe is destroyed, if we fail and it is destroyed, the information which might have saved it still could be found, but too late, of course, to be of any use to us, on that probable world?”
'Yes,' said the Engineer, 'but there would be no one to find it then. The solution would be there, never used, at a time when it would be too late to use it. It is so hard to explain this thought as it should be explained.”
'Maybe it's all right,' said Herb, 'but I crave action. When do we start for this place that might not be there when we get where we headed for?”
'I will show you,' said the Engineer.
They followed him through a maze of laboratory rooms until they came to one which boasted only one piece of equipment, a huge polished bowl set in the floor, blazing with reflected light from the single lamp that shone in the ceiling above it.
The Engineer indicated the bowl. 'Watch,' he told them.
He walked to a board on the opposite wall and swiftly set up an equation on a calculating machine. The machine whirred and clicked and chuckled and the Engineer depressed a series of studs in the control board. The inside of the bowl clouded and seemed to take on motion, like a gigantic whirlpool of flowing nothingness. Faster and faster became the impression of motion.
Gary found himself unable to pull his eyes away from the wonder of the bowl — as if the very motion were hypnotic.
Then the swirl of motion began to take form, misty, tenuous form, as if they were viewing a strange solar system from a vast distance. The solar system faded from view as the vision in the bowl narrowed down to one planet. Other planets flowed out of the picture and the one grew larger and larger, a ball swinging slowly in space.
Then it filled all the bowl and Gary could see seas and cities and mountains and vast deserts. But the mountains were not high, more like weathered hills than mountains, and the seas were shallow. Deserts covered most of the spinning globe and the cities were in ruins.
There was something tantalizingly familiar about that spinning ball, something that struck a chord of memory, something about the solar system — as if he had seen it once before.
And then it struck him like an open hand across his mouth.
'The Earth!' he cried. 'That is the Earth!”
'Yes,' said the Engineer, 'that is your planet, but you see it as it will be many millions of years from now. It is an old, old planet.”
'Or as it may never be,' whispered Caroline.
'You are right,' said the Engineer. 'Or as it may never be.”
Chapter Eleven
Tommy Evans' ship rested on one of the lower roofs of the city, just outside the laboratories level. In a few minutes now it would be lifted and hurled through a warp of space and time that should place it upon the Earth they had seen in the swirling bowl… an Earth that was no more than a probability… an Earth that wouldn't exist for millions of years if it ever existed.
