“Now some of this light may have to travel a hundred years before it reaches a star. When it does it mixes with other light and is reflected back in another hundred years to us. But—mark you this—but it still carries the image of the earth and what happened on the earth when it was here.”
“But you don’t see that,” said Tubby. “We see the star. Ain’t I right?”
“Yes,” said the professor. “Of course you’re right. And the reason we see the star is because that image is the last one the light got. That is predominate. All the others are there—but they are hidden away beneath the star image.”
“Oh,” said Tubby.
“Nobody ever knew they were there, and so of course nobody ever tried to get them out. But I knew they were there— that’s the Oats Theory of the Rationality of Light. And I have got them out!” His voice rose in triumph. “That’s the Light Machine—the greatest invention in the history of the world!”
“Oh, the Light Machine,” said Tubby, when the professor paused.
“The Oats Light Machine—here it is—the only one in the world. I’ll show you at once.”
He switched off the lights. The room was quite dark except for a little beam of white light that seemed to thread its way through the intricate system of mirrors and prisms of the Light Machine. Tubby could not see where this light came from or where it went to. But he saw distinctly that it turned several corners and was alternately broad and narrow. It was white throughout most of its course; but in one short span it was a dark, angry red, and in another a deep, beautiful purple.
“The Light Machine,” the Professor began; his fingers caressed one of its little reflectors lovingly, “is able to extract from light all the images it holds, no matter how long they have been there.”
“That’s wonderful, ain’t it?” said Tubby with admiration.