Dua said, "Don't just sit silently, left-dear. Tell me. I want to know." She had adopted (unconsciously?) the ovoid character of a Rational, as though to make it clearer that she wanted to be accepted as one.
Odeen said, "I can't explain it all. All the science I mean, because you haven't had the background, I will try to make it simple and you just listen. Later, you tell me what you didn't understand and I'll try to explain further. You understand, first, that everything is made up of tiny particles called atoms and that these are made up of still tinier subatomic particles."
"Yes, yes," said Dua. "That's why we can melt."
"Exactly. Because actually we are mostly empty space. All the particles are far apart and your particles and mine and Tritt's can all melt together because each set fits into the empty spaces around the other set. The reason matter doesn't fly apart altogether is that the tiny particles do manage to cling together across the space that separates them. There are attractive forces holding them together, the strongest being one we call the nuclear-force. It holds the chief subatomic particles very tightly together in bunches that are spread widely apart and that are held together by weaker forces. Do you understand that?"
"Only a little bit," said Dua.
"Well never mind, we can go back later… Matter can exist in different states. It can be especially spread out, as in Emotionals; as in you, Dua, It can be a little less spread out, as in Rationals and in Parentals. Or still less so, as in rock. It can be very compressed or thick, as in the Hard Ones. That's why they're hard. They are filled with particles."
"You mean there's no empty space in them."
"No, that's not quite what I mean," said Odeen, puzzled as to how to make matter clearer. "They still have a great deal of empty space, but not as much as we do. Particles need a certain amount of empty space and if all they have is that much, then other particles can't squeeze in. If particles are forced in, there is pain. That's why the Hard Ones don't like to be touched 1?y us. We Soft Ones have more space between the particles than are actually needed, so other particles can fit in."
Dua didn't look at all certain about that. Odeen hastened onward. "In the other Universe, the rules are different. The nuclear-force isn't as strong as in ours. That means the particles need more room."
"Why?"
Odeen shook his head, "Because-because-the particles spread out their wave-forms more. I can't explain better than that. With a weaker nuclear-force, the particles need more room and two pieces of matter can't melt together as easily as they can in our Universe."
"Can we see the other Universe?"
"Oh, no. That isn't possible. We can deduce its nature from its basic laws. The Hard Ones can do a great many things, though. We can send material across, and get material from them. We can study their material, you see. And we can set up the Positron Pump. You know about that, don't you?"
"Well, you've told me we get energy out of it. I didn't know there was a different Universe involved… What is' the other Universe like? Do they have stars and worlds the way we do?"
"That's an excellent question, Dua." Odeen was enjoying his role as teacher more intensely than usual now that he had official encouragement to speak. (Earlier he always had the feeling that there was a kind of sneaking perversion in trying to explain things to an Emotional.)
He said, "We can't see the other Universe, but we can calculate what it must be like from its laws. You see, what makes the stars, shine is the gradual combination of simple particle-combinations into more complicated ones. We call it nuclear fusion."
"Do they have that in the other Universe?"
"Yes, but because the nuclear-force is weaker, fusion is much slower. This means that the stars must be much, much bigger in the other Universe otherwise not enough fusion would take place to make them shine. Stars of the other Universe that were no bigger than our Sun would be cold and dead. On the other hand, if stars in our Universe were bigger than they are, the amount of fusion would be so great it would blow them up. That means that in our Universe there must be thousands of times as many small stars as there are larger stars in theirs-"
"We only have seven-" began Dua. Then she said, "I forgot."
Odeen smiled indulgently. It was so easy to forget the uncounted stars that could not be seen except by special instruments. "That's all right. You don't mind my boring you with all this."
"You're not boring me," said Dua. "I love it. It even makes food taste so good." And she wavered between the electrodes with a kind of luxurious tremor.
Odeen, who had never before heard Dua say anything complimentary about food, was greatly heartened. He said, "Of course, our Universe doesn't last as long as theirs. Fusion goes so fast that all the particles are combined after a million lifetimes."
"But there are so many other stars."
