by Lucy Hawking
This shows that time cannot be absolute, as Newton thought: That is, one cannot assign a time to each event to which everyone will agree. Instead, each person will have their own measure of time, and the times measured by two people that are moving relative to each other will not agree.
This has been tested by flying a very accurate atomic clock around the world. When it returned, it had measured slightly less time than a similar clock that had remained at the same place on the Earth. This means you could extend your life by constantly flying around the world! However, this effect is very small (about 0.000002 second per circuit) and would be more than canceled by eating all those airline meals!
Chapter Twelve
George shot out of the other end of the tunnel, skidding facedown along a stretch of bare rock. His vision was still blurry from the bright, swirling lights of the silvery tunnel. For a second he saw stars before his eyes; then he lifted his head and saw thousands more of them, burning brightly in the black sky around him.
As he peered up, he saw something else. A large black boot appeared in front him, and then another. George rolled over and looked up at a figure in a black space suit looming over him, its face hidden by the darkened glass of the space helmet. It didn’t make any difference. George didn’t need to see his features to know that this was Dr. Reeper: the thwarted scientist and madman was on the loose in the Universe once more.
Behind Reeper’s head there was an immense expanse of sky, so dark that his shape seemed to blend into it. Beside him, George could see nothing but bare gray rock pitted with great craters. He struggled to sit up, his muscles jellified by the journey.
“You can stand,” said Reeper drily. “I picked an asteroid with enough mass that you wouldn’t float off.”
When George had landed on a comet, on his first space journey with Annie, they’d had to tether themselves to the potato-shaped ball of rock and ice because its gravitational force was not strong enough to keep them on the surface. While the comet had been mostly dust, ice, and frozen gas, this asteroid was bigger, and made from much denser material: The gravity here seemed to be holding George firmly in place.
“Where are we?” he wondered, staggering a little as he got to his feet.
“Don’t see anything you recognize?” asked Reeper. “No lovely blue-green planet hanging in the distance, just waiting for you to save it?”
George could see nothing but stars. The mouth of the tunnel had disappeared entirely, leaving him no escape from Reeper and this strange, rocky place.
“Of course you don’t,” continued Reeper. “You wouldn’t recognize much of your own Galaxy if I’d taken you out into the Milky Way. But you are no longer in your home Galaxy. You’ve journeyed farther than ever before.”
“Are we in another Universe?” asked George. “Was that a wormhole?”
“No,” said Reeper. “That’s my updated version of the portal. A doorway seems terribly old school, don’t you think? Eric always was such a traditionalist. You wouldn’t think it, would you? His theories tore up everything we thought we knew about the Universe, and yet when it comes to designing a portal, he models it on his own front door.
“This, George, is Andromeda.”
ANDROMEDA
The Andromeda Galaxy (also known as M31) is the nearest large galaxy to our own Milky Way, and together they are the largest objects in our Local Group of galaxies. The Local Group is a group of at least forty nearby galaxies that are strongly influenced by each other’s gravity.
At 2.5 million light-years away, Andromeda is not actually the closest galaxy to us (that title probably goes to the Canis Major dwarf galaxy), but is the closest with a comparable size and mass.
Current estimates suggest that the Milky Way has more mass (including dark matter), but Andromeda has more stars.
Andromeda has a spiral shape, like the Milky Way.
Like the Milky Way, Andromeda has a super-massive black hole at its center.
Also like the Milky Way, Andromeda has several (at least fourteen) satellite dwarf galaxies in orbit around it.
“Another galaxy … ?” said George in awe.
“Our neighbor,” confirmed Reeper, sweeping an arm around him. “This is, if you like, the galaxy equivalent of the house next door. Given the size of the Universe, it might as well be. Notice anything?”
“The stars look the same … ,” said George slowly. “This asteroid looks like an asteroid. I suppose we must be orbiting a star, so we’re in another solar system. It’s not so very different from being in the Milky Way.”
“Yes, indeed,” agreed Reeper. “Remarkable, isn’t it? Close up, no two pieces of rock are exactly the same. No two planets, no two stars, no two galaxies. Some regions of space contain just clouds of gas and dark matter, but in other places you find stars, asteroids, and planets. So much variety! Yet here we are, two and half million light-years away from Earth, and things don’t look that different. This asteroid could be in our own Solar System; those stars could be in our own Milky Way. The variations here are the same as in our own Galaxy. What do you think that means, George? Answer me that and I’ll tell you why we are here.”
“It means,” said George, thinking about Eric’s lecture, “that everything everywhere was formed in the same way, from the same material and by the same rules, but the tiny fluctuations at the beginning of time caused everything to turn out a little bit different from everything else.”
UNIFORMITY IN SPACE
In order to apply General Relativity to the Universe as a whole, we usually make some assumptions:
every location in space should behave in the same way (homogeneity)
and every direction in space should look the same (isotropy).
This leads to a picture of the Universe that is
uniform in space
starts with a Big Bang
and then expands equally everywhere.
This picture is strongly supported by astronomical observations—what we can see in space through telescopes on the ground and in space.
Yet the Universe can’t be exactly uniform in space, because this would mean that structures like galaxies, stars, solar systems, planets, and people couldn’t exist. A pattern of tiny ripples over the uniformity is needed to explain how the first patches of gas and dark matter could begin to collapse, so that the laws of physics could go on to create stars and planets.
Because the gas and dark matter start out nearly uniform, and because we believe the same laws of physics apply everywhere, we expect that all galaxies form in a similar way. So distant galaxies should have similar types of stars, planets, asteroids, and comets to those that we can see in our own Milky Way.
Where the initial tiny ripples came from is not yet completely understood. The best theory at the moment is that they came from microscopic quantum jitters that were magnified by a very rapid early expansion phase—called inflation—that took place during a very tiny fraction of the first second after the Big Bang.
“Well done! I am glad to know that one of my ex-pupils at least can show that he has benefited from his education.”
“Why have you brought me here?” asked George bravely. “What is it this time?”
“I don’t think I like your tone.” Reeper now sounded more like he had when he’d been a teacher at George’s old school.
“I don’t think I like being catapulted into space by a talking hamster,” George shot back at him.
“Of course,” said Reeper hastily. “I can see that was a bit of a surprise. But I had no other way of contacting you.”
“Oh, really?” said George. “Didn’t you break into my house at night and leave a note in my schoolbook?”
“Yes, yes, I did,” said Reeper. He seemed unusually nervous, unlike the Reeper of old, who was always totally confident of his evil powers. “I was trying to attract your attention. I couldn’t find Eric next door so I came and left a note for you instead.”
“Why didn’t you just come and talk to m
e, if it was so important?”
“Because I can’t,” said Reeper in frustration. “I can’t go anywhere or do anything—I’m trapped. Since I slipped away to your houses the other night, they’ve put me under even closer surveillance. They don’t know I visited you, but they know I went somewhere and it has made them suspicious. That’s why I had to meet you in space. It’s the only safe place for us to talk. I couldn’t possibly have contacted you—and certainly not Eric—by earthly means. I would have blown our only chance of stopping them.”
“Who is it who’s watching you?” asked George.
“Them,” said Reeper. “TOERAG. They are everywhere.” He looked around as he spoke, as though they might be floating past the asteroid in this unknown part of the Andromeda galaxy. “They are the unseen, the dark force. They are all around us.”
“I think that’s dark matter you’re thinking of,” said George. “The invisible material that makes up twenty-three percent of the known Universe.”
“George,” said Reeper earnestly, “you are so right. They are humanity’s dark matter. You can’t see them, but you know they are there by the effect they have on the Universe around them.”
For once, he seemed to be speaking from the heart—if indeed he actually had one.
“Were they the people in black at Eric’s lecture?” demanded George.
“That was a few of them. There are many more—they are a vast network. I was there too at the demonstration—I couldn’t get near you so I tried to alert you via that boy but it didn’t work.”
“I knew it!” said George. “I knew it was you! But I couldn’t work out why. I don’t understand why TOERAG is doing this. Why would it be so bad if Eric discovered the Theory of Everything? Why would it be so dangerous to understand the origins of the Universe?”
“For you and me it would be a great step forward. For TOERAG it would be a terrible, wounding blow.”
“Because of the True Vacuum,” asked George, “and what it might do?”
“The leaders don’t really believe that the Universe will be ripped apart in a growing bubble of destruction, leaked from the Large Hadron Collider,” Reeper told him. “That’s just a terrible apocalyptic prospect they use to frighten people into joining their organization so that their network keeps on growing. What they’re really scared of is something very different.”
“Such as?”
The asteroid sped onward on its orbit, circling a very bright young star that was a few billion years younger than our Sun. As George watched, two hundred-yard-long chunks of rock smashed into each other with the energy of a nuclear explosion. A cloud of pulverized dust expanded outward. This young solar system was a very violent place, with many such chunks hurtling around the central star. Eventually planets would form and vacuum up all the debris left lying around after these collisions, but for now, it was a chaotic, dangerous place to be. Although, thought George, from what Reeper had to say, it sounded like almost anywhere in the Universe was a better bet than planet Earth right now.
“The leaders of TOERAG are convinced that Eric’s experiments will eventually have other results,” said Reeper. “Once we have the Theory of Everything, they believe that scientists will be able to use this knowledge in a number of ways. For example, they think it will become possible to create a new source of clean, cheap renewable energy.”
“But who doesn’t want that?” cried George.
“I have hacked into their secret membership files,” Reeper explained, “so I am one of the very few people who can actually identify the leaders of TOERAG. It’s made up first of big companies—who would prefer us to keep on using coal, oil, gas, or nuclear energy rather than look for sources of renewable energy. They think that experiments at the LHC might one day give us the clue as to how to produce clean, cheap energy and they don’t want that.”
“Urgh!” said George. “You mean the people who mess up the seas and poison the atmosphere with greenhouse gases?” He thought of his eco-activist parents and how they tried their hardest to protect the planet. They were just normal, ordinary, kind people who wanted to make a difference to the future of the life on Earth. What chance did they have against such powerful opponents?
“Not just them,” warned Reeper. “There’s also a group within TOERAG who think that once we find one unified theory for the four forces, it will result in the elimination of war. They think that we will come to understand that we are all the same, all part of the same human race. This could raise our awareness of the problems on planet Earth, end competition for resources, and make the rich countries want to help the poor nations.”
“Don’t they want peace?” George was bewildered.
“No,” said Reeper shortly. “They make a lot of money selling weapons so that people can kill each other. They’d really prefer it if we kept waging war.”
“Anyone else?” said George.
“Well, there are a few astrologers who think their predictions will become worthless once Eric and the other scientists can explain everything. So they won’t be able to make money by telling your fortune on the Internet. There’s a television evangelist who fears that no one will want to be saved by him if Eric is successful. Another group has joined out of fear—fear of science and what it will do in the future. There are even some scientists.”
“Scientists?” said George in shock. “Why would they join TOERAG?”
“Well, there’s me, for a start,” said Reeper. “I didn’t really join—I infiltrated TOERAG in order to spy on them. I heard about this secret, anti-science organization, and so to find out more, I became one of their number—my codename is Isaac, after one of the greatest scientists of all, Isaac Newton. In order to gain acceptance, I lied and told them that Eric and I were still sworn enemies. No one yet knows that he and I made peace with each other, so they believed me and let me in.”
“Does Eric know you are part of TOERAG?” asked George.
“No,” admitted Reeper. “I wish he did. I wanted to talk to him about their plans, but I realized it would put him in even more danger if I contacted him directly.”
“Who are the other scientists?”
“That’s more difficult,” said Reeper. “We’re never allowed to meet each other. We have separate jobs to do and our paths never cross.”
“What was your job?”
“My job”—there was a trace of pride in Reeper’s voice—“was to create a bomb, a really powerful and intelligent one. They wanted me to make a bomb that would be impossible to defuse. The thing about most bombs is that you can cut the wires to stop them detonating. TOERAG wanted a bomb that even if you snipped the wires or knew the code, you still couldn’t prevent the explosion. They said,” Reeper added hastily, “it was just a prototype, for experimental purposes only.”
“You didn’t really do it, did you?” asked George. “I mean, you didn’t actually make a bomb that works and give it to a dangerous underground anti-science group?”
“Of course I did!” said Reeper, sounding startled. “How could I make something that didn’t work?”
“Duh, quite easily!” said George. “Then it wouldn’t be able to blow anything up. Problem solved!”
“But I’m a scientist!” bleated Reeper. “I can’t make something that doesn’t work! I have to get it right—otherwise I’m not a scientist! And that would be …” He trailed off.
“You’d better tell me about this bomb,” George said, trying to be patient.
“Right, well,” said Reeper, sounding more enthusiastic. “It’s really brilliant! And it can blow up anything—I mean, just anything!”
“Yup, I got that,” said George. “You keep on telling me.”
“Sorry, sorry!” said Reeper. “Okay, I designed a bomb with eight switches. You input a code on a numerical pad to make the switches go live. Then, when you push all eight of the switches, it creates a superposition of eight states. Once all eight switches are thrown, the countdown automatically begins.”
; “So what is the really super-clever part?” asked George.
“Because it’s a quantum mechanical bomb”—Reeper sounded like he was boasting, just a little—“it has created a quantum superposition of the different alternatives inside the detonator. This means that anyone who tries to defuse the bomb by cutting one of the cables or flipping one of the switches would just blow themselves and everyone else up. That’s the point—they wanted a bomb that couldn’t be shut down, in case there were traitors inside TOERAG.”
“I don’t get it,” said George.
“The bomb has been armed in such a way that no one switch can turn it off; it is in a quantum superposition of eight different possible switches. The detonator does not ‘decide’ which switch is actually being used until someone presses one to try to stop the bomb going off, and the circuit checks whether it is correct. At that point the wave function collapses randomly to one of the eight possible alternatives. Even if you pressed all eight at once, the bomb will very probably detonate immediately. What I mean is—it will explode, no matter what you do to it.”
“Why did you do this?” asked George grimly.
“Because I wanted someone to know how clever I am,” said Reeper sulkily. “I didn’t realize they actually intended to use the wretched thing. They said it was just an experiment.”
“And where is this impossible-to-defuse quantum mechanical bomb?”
“Well, I don’t know!” said Reeper, sounding panicky. “That’s the problem—it’s gone!”
“Gone where?”
“They’ve taken it away. And from what I’ve learned by hacking into their computers, it looks like they mean to use it, after all. Where’s Eric?”
