George's Cosmic Treasure Hunt Read Free Page B

minutes to reach us; from the next nearest star it takes more than four years.

    Very hot objects in space, such as stars, produce visible light, which may travel a very long way before hitting something. When you look at a star, the light from it may have been moving serenely through space for hundreds of years. It enters your eye and, by jiggling electrons in your retina, turns into electricity that is sent along the optic nerve to your brain. Your brain says, “I can see a star!” If the star is very far away, you may need a telescope to collect enough of the light for your eye to detect, or the jiggled electrons could instead create a photograph or send a signal to a computer.
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    The Universe is constantly expanding, inflating like a balloon. This means that distant stars and galaxies are moving away from Earth. This stretches their light as it travels through space toward us—the farther it travels, the more stretched it becomes. The stretching makes visible light look redder, which is known as the redshift. Eventually, if light traveled and redshifted far enough, the light would no longer be visible and would become first infrared, and then microwave (as used on Earth in microwave ovens), radiation. This is just what has happened to the incredibly powerful light produced by the Big Bang. After thirteen billion years of traveling, it is detectable today as microwaves coming from every direction in space. This has the grand title of cosmic microwave background radiation , and is nothing less than the afterglow of the Big Bang itself.
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    Annie said all this matter-of-factly, as though it were quite normal to know this kind of information and be able to rattle it off at parties. But once again George felt a little jealous of her. He loved science and was always reading books, looking up articles on the Internet, and pestering Eric with questions. He wanted to be a scientist when he grew up, so he could learn everything there was to know and maybe make some amazing discovery of his own. Annie, on the other hand, was much more casual about the wonders of the Universe.
    When George had first met Annie, she’d wanted to be a ballerina, but now she’d changed her mind and decided on being a soccer player. Instead of spending her time after school in a pink-and-white tutu, she now charged around the backyard, hammering a soccer ball past George, who always had to be goalie. And yet she still seemed to know far more about science than he did.
    Annie’s dad, Eric, now appeared, dressed in his normal clothes and looking no different from usual.
    â€œEric,” cried George, who was bursting with questions. “What have you come as?”
    â€œOh, me?” Eric smiled. “I’m the only intelligent life-form in the Universe,” he said modestly.
    â€œWhat?” asked George. “You mean you’re the only intelligent person in the whole Universe?”
    Eric laughed. “Don’t say that too loudly around here,” he told George, gesturing to all the other scientists.“Otherwise people will get very upset. I meant, I’ve come as a human being, which is the only intelligent form of life in the Universe that we know about. So far.”
    â€œOh,” said George. “But what about all your friends? What have they come as? And why does red light mean something is going away? I don’t understand.”
    â€œWell,” said Eric kindly, “you’d understand if someone explained it to you.”

    â€œCan you explain it to me?” pleaded George. “All about the Universe? Like you did with the black holes? Can you tell me about red thingies and dark matter and everything else?”
    â€œOh dear,” said Eric, sounding rather regretful. “George, I’d love to tell you all about the Universe, but the problem is, I’m just not sure I’ll have time before I have to…Hang on a second…” He trailed off and gazed