"The telescope is pointed into one of the other two worlds," Carl was explaining. "Without a physical solid connecting the two there is no contact."
"What is the nature of that?" Hute asked, pointing at the glowing square surface.
"It's difficult to explain it," Carl answered, "I'll put it this way. Two attracting bodies that are close enough together will revolve around each other, like the sun and our planet, Amba. The material of this slab is what I have named tri-matter. It consists of matter from all three universes of our time equation, blended into one solid. Before I was able to contact these other two universes it was necessary to use the machine, which took incredible power to operate for a few brief moments, and had to be so delicately controlled that the slightest vibration unbalanced its adjustment. Once the materials were gathered and blended so they could not separated, I had a permanent bridge into the other worlds. The machine and its incredible power were no longer needed.
"You must remember that the three universes occupy the same space, so that spatially they are not separated at all. Their separation was temporal, and at right angles to the path from the past into the future. The attracting forces of the atoms had to be directed across this plane of time by the machine. When that took place the materials had to be brought together so that the three substances blended would cohere. Once they were brought into that state the bridge was established. The bridge is anchored at this end in the matter of our universe and at the other two ends in the matter of those universes, just as the bridge above this building is anchored on this side to the matter of the bank of this side of the river, and on the other to the matter there."
"And you just have to walk across?" Hute asked.
"That's all there is to it," Carl replied casually.
"And," Hute's eyes took on a crafty gleam. "A time machine in one of these other universes could carry me to any point in the future without danger it might have encountered in this one, such as an atom bomb dropped on the space it would have been in here?"
"That's correct," Carl agreed. "If you will look through the telescope you will see my aides already nearing completion on the time machine."
Hute placed his eyes to the telescope. The scene that appeared was quite a normal one. The landscaping was different in many ways. The vegetation was prolific and of strange forms. But for a considerable area the ground was flat, meeting the surface of the ordinary world only at the one spot where the tri-matter block was anchored.
A dozen workmen were busy on the conventional time machine. Hute could see that a few more days would see it completed. He took his eyes away, satisfied.