“An infinite number,” he replied smilingly. “A number that cannot be conceived. Each has distinct characteristics, just as iron differs from lead or gold.”
He paused a moment, but none of us said anything. “With this conception,” he went on, “we can build the definition that a material substance is a density of other substances. It maintains its separate existence by virtue of having around its exterior an emptiness greater than the emptiness of its interior. Think of that a moment.
“The earth itself is such a density. The space around it is greater than any of the spaces within its molecules, its atoms, its electrons—down to its finitely small intimes—to the ultimate nothingness of which it is composed.
“That is our earth. It is in movement. And another density near it we call Venus, and another Mars, vibrating with a space between them. All our starry universe; you see, Leonard?”
My mind leaped with the thrill of it. The great vault of the heavens with its myriad whirling stars shrank before my far-flung imagination into a tiny space teeming with its agitated particles!
Dr. Weatherby added gently, “A fragment of iron is microscopically no different in structure from our starry universe. The distances between our heavenly bodies compared to the size of them are quite the same as the distances between electrons, or intimes, compared to their size. You get my point?”
“I do,” Jim exclaimed. “What we call the sky would seem a solid mass of matter—like a fragment of iron—to some greater viewpoint?”
“Exactly. Our microscopes show nothing which is actually more solid than the sky itself. From here, on earth, to the Milky Way is to us a tremendous distance. But suppose that we were so gigantic—so vast in comparative size—that we needed a powerful microscope even to perceive that space. What would we see? A multiplicity of vibrating particles! And without the microscope the whole space would seem solid. We could call it . . . well, say a grain of gold.”
For a moment we were silent. There was to all this an awesome aspect. Yet its actual simplicity was overwhelming.
Dolores said timidly, “It seems strange that so simple a thing should have been unknown for so long.”