George's Cosmic Treasure Hunt (3 page)
Read George's Cosmic Treasure Hunt Online
Authors: Lucy Hawking
“Um, well,” said George. “I'm the Man from Marsây'know, from the pictures.”
“Oh yeah!” said Annie. “You can be my Martian ancestor. That's cool.”
Around them, the party was buzzing. Groups of the most oddly dressed grown-ups stood eating and drinking and talking at the tops of their voices. One man had come dressed as a microwave oven, another as a
rocket. There was a lady wearing a badge shaped like an exploding star and a man with a mini satellite dish on his head. One scientist was bouncing around in a bright green suit, ordering people to “Take me to your leader”; another was blowing up an enormous balloon stamped with the words
THE UNIVERSE IS INFLATING
. A man dressed all in red kept standing next to people and then stepping away from them, daring them to guess what he was. Next to him was a scientist wearing lots of different-sized hula hoops around his middle, each one with a different-sized ball attached to it. When he walked, his hula hoops all spun around him.
“Annie,” said George urgently, “I don't understand any of these costumes. What have these guests come as?”
“Um, well, they've all come as things you'd find in space, if you know how to look for them,” said Annie.
“Like what?” asked George.
“Well, like the man dressed in red,” explained Annie. “He keeps stepping away from people, which means he's pretending to be the redshift.”
“The what?”
“If a distant object in the Universe, like a galaxy, is moving away from you, its light will appear more red than otherwise. So he's dressed in red, and he is moving
away
from people to show them he's come as the redshift. And the others have come as all sorts of cosmic stuff that you'd find out there, like microwaves and faraway planets.”
LIGHT AND HOW IT TRAVELS THROUGH SPACE
One of the most important things in the Universe is the
electromagnetic field
. It reaches everywhere; not only does it hold atoms together, but it also makes tiny parts of atoms (called
electrons
) bind different atoms together or create electric currents. Our everyday world is built from very large numbers of atoms stuck together by the electromagnetic field. Even living things, like human beings, rely on it to exist and to function.
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Jiggling an electron creates waves in the field. This is like jiggling a finger in your bath and making ripples in the water. These waves are called
electromagnetic waves
, and because the field is everywhere, the waves can travel far across the Universe, until stopped by other electrons that can absorb their energy. They come in many different types, but some affect the human eye, and we know these as the various colors of visible light. Other types include radio waves, microwaves, infrared, ultraviolet, X rays, and gamma rays. Electrons are jiggled all the time by atoms that are constantly jiggling too, so there are always electromagnetic waves being produced by objects. At room temperature the waves are mainly infrared, but in much hotter objects the jiggling is more violent, and produces visible light.
Light travels at 186,000 miles per second. This is very fast, but light from the Sun still takes eight 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 usâthe 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.
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.
“Eric,” cried George, who was bursting with questions. “What have you come as?”
“Oh, me?” Eric smiled. “I'm the only intelligent life-form in the Universe,” he said modestly.
“What?” 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.”
“Oh,” 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.”
“Well,” said Eric kindly, “you'd understand if someone explained it to you.”
“Can
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?”
“Oh 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 toâ¦Hang on a second⦔ He trailed off and gazed into the distance, the way he did when he was having an idea. He took off his glasses and polished them on his shirt, setting them on his nose at the same off-kilter angle as before. “I've got it!” he cried, sounding very excited. “I know what we need to do! Hold on, George, I've got a plan.”
With that, he picked up a soft hammer and struck a huge brass gong, which rang out with a deep, humming chime.
“Right, gather round, everyone,” said Eric, waving
everyone into the room. “Come on, come on, hurry up! I've got something to say.”
A ripple of excitement went through the crowd.
“Now then,” he went on, “I've gathered the Order of Science here today for this partyâ”
“Hurray!” cheered someone at the back.
“And I want us to put our minds to some questions my young friend George has asked me. He wants to know all sorts of things! For a start, I'm sure he'll want to know what your costume is!” He pointed to the man wearing the hula hoops.
“I've come to the party,” piped up the cheerful-looking scientist, “as a distant planetary system where we might find another planet Earth.”
“Annie,” whispered George, “isn't that what Doctor Reeper did? Find new planets?”
Dr. Reeper was a former colleague of Eric's, who wanted to use science for his own selfish purposes. He had told Eric he'd found an exoplanetâthat is, a planet in orbit around a star other than the Earth's Sunâthat might be able to support human life. But the directions he'd given Eric had been bogusâin fact, in his search for the planet, they had sent Eric dangerously close to a black hole. Dr. Reeper had been trying to get rid of Eric so he could control Cosmos, Eric's supercomputer. But his evil trick hadn't worked, and Eric had returned safely from his trip inside a black hole.
No one knew where Dr. Reeper was now. He had fled after his master plan backfired. At the time, George had begged Eric to do something about him, but Eric had just let him go.
“Doctor Reeper knew how to
look
for planets,” said Annie, “but we don't know whether he ever actually found one. After all, that planet he wrote about in the letter to Dad? We never got to see whether it really existed or not.”
“Thank you, Sam. And how many planets have you
found so far?” Eric questioned the hula hoop man.
“So far,” replied Sam, shaking his hoops as he spoke, “three hundred and thirty-one exoplanetsâmore than a hundred of them in orbit around stars quite nearby. Some of these stars have more than one planet going around them.” He pointed to his hula hoops. “I'm a nearby system with planets in orbit around its star.”
“What does he mean by ânearby'?” George whispered to Annie, who passed the message on to Eric. Her father whispered back to her, and she then relayed the answer to George.
“He means, maybe, like, about forty light-years away. So, like, about two hundred and thirty-five trillion miles,” said Annie. “Nearby for the Universe!”
“Have you seen anything that might be like the Earth? A planet we could call home?”
“We've seen a few that mightâand only mightâbe like a second Earth. Our planet-hunting search continues.”