George and the Big Bang

by Lucy Hawking

  “What for?” muttered Annie, struggling to keep up with George. “Why would so many people want to come and hear my dad talk about math?”

  They ducked and wove their way up the steps to where the official stood guard. Immediately he held out his arm to stop them from going in.

  “No entrance to the professor’s talk!” he snapped.

  “Excuse me,” said Susan politely, “but I am Professor Bellis’s wife, and this is his daughter, Annie, and her friend George. We’ve come to help set up the hall for Eric’s talk.”

  “Oh, I am sorry, Mrs. Professor!” said the official apologetically. “We don’t usually do security for the Math Department—it’s not like this place to cause much of a stir!” He took a handkerchief out and mopped his brow. “But it seems your husband has become pretty famous.”

  As Susan and the two children turned to look at the waiting people, they heard a sudden commotion from the back of the crowd.

  “Stop the criminal scientist!” came the chant. A small line of people dressed in black, wearing masks, were waving banners. “Don’t let the advance of science destroy our Universe!”

  The official looked horrified and spoke quickly into his two-way radio. “Math Department—send back-up. Get inside, Mrs. Bellis,” he said, opening the door and ushering Susan and the kids through. “We’ll deal with the likes of them,” he muttered grimly. “We don’t tolerate this kind of behavior in Foxbridge. It just isn’t done around here.”

  Chapter Six

  Once they were inside, Susan quickly dragged the gaping kids away from the doors and through the entrance hall. They made their way into the big auditorium. “Ignore what’s going on outside. Put one of these on every seat,” Susan said calmly, giving them each a small cardboard box containing dozens of pairs of dark glasses.

  Everything was nearly ready for Eric to take to the stage and give his very first public lecture as the new professor of mathematics at the ancient and very brilliant University of Foxbridge.

  Annie and George moved between the rows, carefully putting one pair of glasses on each chair. Annie had for once been really scared by the protestors outside, and she was still trembling slightly.

  “Mom, what’s going on?” she asked. “Are those the people from TOERAG—that organization Dad was telling us about?”

  “I don’t exactly know,” her mom replied gently. “But they do seem to be objecting to your father’s experiments to explore the origins of the Universe. They believe that they are just too dangerous and should be stopped before they can go any further.”

  “But that’s crazy!” said George. “We know that Eric’s experiments are safe! And they might show us how the Universe really began. They’re, like, the final piece of a jigsaw puzzle that scientists have been working on almost forever! We can’t just throw the last piece away before we’ve seen the whole picture.”

  By now, they’d worked their way along all the rows from the big double doors at the back of the hall right to the front, where Eric would be speaking. The doors suddenly flew open, and a tall boy zoomed down toward them. He leaped off his skateboard and landed next to George, the wheels still spinning as he caught it in his hands.

  “Ta-dah!” he announced.

  “Vincent!” squeaked Annie in delight. “I didn’t know you were coming. At least I’ve got one friend here!” she added pointedly in George’s direction.

  “I thought the doors were locked,” George muttered grumpily, wishing they still were.

  “They just opened them, and”—Vincent pointed to his skateboard—“I rode straight to the front of the line.”

  “Have all the people in black gone?” asked Annie. Fans were now streaming into the lecture hall, taking their seats, examining the dark glasses left on the chairs and wondering why they might need them.

  “Yup, they’ve legged it,” said Vincent. “Weirdos. What was all that about? ‘Criminal scientist’—the morons!” Annie was smiling at Vincent in a way that made George want to pull her hair quite sharply, just to wipe that look off her face.

  “One of them tried to talk to me,” Vincent added, flipping his board up and down with his left foot.

  “What did he say?” asked George.

  “I couldn’t really make it out,” admitted Vincent. “He had a mask on, so I suppose it was like trying to speak through a woolly sock. But it did sound as if he was trying to say a word.”

  “What word?” asked George curiously.

  Vincent eyed him cautiously. “To be honest, buddy,” he said, “it sounded like he was saying your name. It sounded like he said ‘George.’ ”

  “Why would one of the protesters be saying ‘George’?” asked Annie in confusion.

  “Maybe he wasn’t saying George,” said Vincent very reasonably. “Maybe it just sounded like that. Or perhaps that word means something else in I’m-a-crazy-person-who-dresses-up-in-black-for-no-good-reason language. My dad always has trouble at his film premieres,” he bragged. “You’re really no one at all if you don’t have a few loony fans. It’s just, like, one of the things that goes with being famous.”

  “Oh, yeah,” said Annie admiringly. “Film premieres. That must be so, like, amazing!”

  “Yeah,” echoed George vaguely. “Amazing!” He wasn’t even being sarcastic. He was too preoccupied with wondering why someone at the protest would be saying his name. There must be a connection, he thought, between the strange people in the abandoned college cellar underneath a tower in Foxbridge and the demonstration outside. Who else would call Eric an evil, criminal scientist other than a faceless group of dark bodies who believed his work had the power to rip the Universe into shreds in a matter of minutes? But how could any of that group know George’s name? How could—?

  At that moment the lights in the hall flashed on and off a couple of times, and a disembodied voice—which George and Annie recognized as Cosmos—told everyone to take their seats.

  “Ladies, gentlemen, kids, and cosmic travelers,” the voice went on. “Today we are going on a journey unlike any you will ever experience. Prepare, ladies, gentlemen, and young travelers! Prepare to meet your Universe!”

  With that, the whole hall went dark.

  Chapter Seven

  George, Annie, and Vincent quickly sat down in their seats. They were on the end of the front row, with just one empty chair next to George. The whole of the rest of the hall was packed with people—there wasn’t another free spot in the house. In the darkness, they heard the audience shuffle and then fall silent.

  “Cosmic travelers,” said Cosmos, his voice booming magnificently across the packed hall. “We have many billions of years to cover. You must be ready! Ready to go back to the beginning, ready to understand how it all began.

  “Please, put on your dark glasses,” he continued. “We will be showing you brilliance and brightness, and we don’t want to damage your eyes.” Above the heads of the audience, a tiny little pinprick of extremely bright white light had appeared, suspended in the middle of the total darkness. All at once George noticed that the seat next to him was no longer empty. A man had snuck in and sat down. George turned to look at him just as Cosmos projected a huge flash of light that illuminated the whole hall. It lasted just long enough for George to see the man sitting next to him and to notice that he was wearing a very unusual pair of glasses in which the glass, instead of being clear or black, was bright yellow.

  Only once in his life had George seen such glasses before. When he, Annie, and Cosmos had rescued Eric from the inside of a black hole, the scientist had come out wearing a pair of identical yellow glasses. They hadn’t belonged to him, and the mystery of what those odd-looking glasses might have been doing in the middle of a super-massive black hole had never been solved.

  “Where did you get those glass—?” George started to ask, but his voice was drowned out by Cosmos.

  “Our story begins thirteen point seven billion years ago.” As Cosmos spoke, the tiny speck of light hovered above thei
r heads, with the hall in darkness once more. “At that time, everything we can now see in the Universe—and everything we can’t see because it is invisible—began as a tiny speck, much smaller than a proton.

  “The available space itself was also tiny, so everything had to be crammed together. If we peer back in time as far as we can, conditions were so extreme that physics can no longer describe exactly what was happening at this moment. But it looks as if space as we know it started at zero size thirteen point seven billion years ago, and then expanded.”

  The dot of light grew very suddenly, like a balloon being inflated. The balloon was slightly transparent, and it was possible to see bright swirling patterns moving all over its surface; otherwise it seemed to have nothing inside.

  “This hot soup of stuff,” continued Cosmos, “will become our Universe. Note that the Universe is only the surface of the sphere—this is a two-dimensional model of three-dimensional space. As the sphere grows, so the surface expands and the contents spread out.

  “Time also began along with space. This is the traditional picture of the Big Bang in which everything, including space and time, comes into being very suddenly at the beginning of history.”

  Above their heads, the balloon exploded outward, and the audience seemed to be absorbed into its hot, swirling surface. The writhing colors twisted, then dimmed and broke up like a cloud, leaving total darkness in the hall. There were “Oohs” and “Aahs” of wonder.

  After a moment, dim, moving patches of light began to appear on the dark ceiling; the patches then took on the shapes of galaxies, spreading out and away from each other until they had all vanished and darkness had returned once again.

  “Was it really like this?” questioned Cosmos. “Some scientists wonder whether the Big Bang really was the beginning of history. We don’t know for sure, but let’s pick up the story at a moment just a minuscule fraction of a second after the Big Bang, when the whole observable Universe was scrunched into a tiny amount of space, smaller than a proton.”

  “Imagine … ,” said another voice, and a spotlight showed Eric, standing on the stage with a big smile on his face. The audience burst into applause. “Imagine that you are sitting inside the Universe at this very early time …”

  THE BIG BANG—A Science Lecture

  Imagine that you are sitting inside the Universe at this very early time (obviously, you couldn’t sit outside it). You would have to be very tough because the temperatures and pressures inside this Big Bang soup are so tremendously high. Back then, all the matter that we see around us today was squeezed into a region much smaller than an atom.

  This would be a tiny fraction of a second after the Big Bang, but everything looks much the same in all directions. There is no fireball racing outward; instead, there is a hot sea of material, filling all of space. What is this material? We aren’t certain—it may be particles of a type we don’t see today; it may even be little loops of “string”; but it will definitely be “exotic” stuff that we couldn’t expect to see now, even in our largest particle accelerators.

  This tiny ocean of very hot exotic matter is expanding as the space it fills grows bigger—matter in all directions is streaming away from you, and the ocean is becoming less dense. The farther away the matter is, the more space is expanding between you and it, so the faster the matter moves away. The farthest material in the ocean is actually moving away from you faster than the speed of light.

  A lot of complicated changes now happen very fast—all in the first second after the Big Bang. The expansion of the tiny Universe allows the hot exotic fluid in the little ocean to cool. This causes sudden changes, like when water changes as it cools to form ice.

  When the early Universe is still much smaller than an atom, one of these changes in the fluid causes a stupendous increase in the speed of expansion, called inflation. The size of the Universe doubles, then doubles again, and again, and so on until it has doubled in size around ninety times, increasing from subatomic to human scale. Like pulling a bedspread straight, this enormous stretching flattens out any big bumps in the material so that the Universe we eventually see will be very smooth and almost the same in all directions.

  On the other hand, microscopic ripples in the fluid are also stretched and made much bigger, and these will trigger the formation of stars and galaxies later.

  Inflation ends abruptly and releases a large amount of energy, which creates a wash of new particles. The exotic matter has disappeared and been replaced by more familiar particles—quarks (the building blocks of protons and neutrons, although it is still too hot for these to form), antiquarks, gluons (which fly between both quarks and antiquarks), photons (the particles light is made of), electrons, and other particles well known to physicists. There may also be particles of dark matter, but although it seems these have to appear, we don’t yet understand what they are.

  Where did the exotic matter go? Some of it was hurled away from us during inflation, to regions of the Universe we may never see; some of it decayed into less exotic particles as the temperature fell. The material all around is now much less hot and dense than it was, though still much hotter and denser than anywhere today (including inside stars). The Universe is now filled with a hot, luminous fog (or plasma) made mainly from quarks, antiquarks, and gluons.

  Expansion continues (at a much slower rate than during inflation), and eventually the temperature falls enough for the quarks and antiquarks to bind together in groups of two or three, forming protons, neutrons and other particles of a type known as hadrons; and also antiprotons, antineutrons, and other antihadrons. Still little can be seen through the luminous foggy plasma as the Universe reaches one second old.

  Now, over the next few seconds, there are fireworks as most of the matter and antimatter produced so far annihilate each other, producing floods of new photons. The fog is now mainly protons, neutrons, electrons, dark matter, and (most of all) photons, but the charged protons and electrons stop the photons traveling very far, so visibility in this expanding and cooling fog is still very poor.

  When the Universe is a few minutes old, the surviving protons and the neutrons combine to form atomic nuclei, mainly of hydrogen and helium. These are still charged, so the fog remains impossible to see through. At this point the foggy material is not unlike what you would find inside a star today, but of course it fills the whole Universe.

  After the frantic action of the first few minutes of life, the Universe then stays much the same for the next few hundred thousand years, continuing to expand and cool down, the hot fog becoming steadily thinner, dimmer, and redder as the wavelengths of light are stretched by the expansion of space. Then, after 380,000 years, when the part of the Universe that we will eventually see from Earth has grown to be millions of light-years across, the fog finally clears—electrons are captured by the hydrogen and helium nuclei to form whole atoms. Because the electric charges of the electrons and nuclei cancel each other out, the complete atoms are not charged, so the photons can now travel uninterrupted—the Universe has become transparent.

  After this long wait in the fog, what do you see? Only a fading red glow in all directions, which becomes redder and dimmer as the expansion of space continues to stretch the wavelengths of the photons. Finally the light ceases to be visible at all and there is only darkness everywhere—we have entered the Cosmic Dark Ages.

  The photons from that last glow have been traveling through the Universe ever since, steadily becoming even redder—today they can be detected as the cosmic microwave background (CMB) radiation and are still arriving on Earth from every direction in the sky.

  The Universe’s Dark Ages last for a few hundred million years, during which time there is literally nothing to see. The Universe is still filled with matter, but almost all of it is dark matter, and the rest hydrogen and helium gas, and none of this produces any new light. In the darkness, however, there are quiet changes.

  The microscopic ripples, which were magnified by inflation, mea
n that some regions contain slightly more mass than average. This increases the pull of gravity toward those regions, bringing even more mass in, and the dark matter, hydrogen and helium gas already there are pulled closer together. Slowly, over millions of years, dense patches of dark matter and gas gather as a result of this increased gravity, growing gradually by pulling in more matter, and more rapidly by colliding and merging with other patches. As the gas falls into these patches, the atoms speed up and become hotter. Every now and then, the gas becomes hot enough to stop collapsing, unless it can cool down by emitting photons, or is compressed by collision with another cloud of matter.

  If the gas cloud collapses far enough, it breaks into spherical blobs so dense that the heat inside can no longer get out—finally, a point is reached when hydrogen nuclei in the cores of the blobs are so hot and squashed together that they start to merge (fuse) into nuclei of helium and release nuclear energy. You are sitting inside one of these collapsing patches of dark matter and gas (because this is where the Earth’s galaxy will be one day), and you may be surprised when the darkness around you is broken by the first of these nearby blobs bursting into bright light—these are the first stars to be born, and the Dark Ages are over.

  The first stars burn their hydrogen quickly, and in their final stages fuse together whatever nuclei they can find to create heavier atoms than helium: carbon, nitrogen, oxygen, and the other heavier types of atom that are all around us (and in us) today. These atoms are scattered like ashes back into the nearby gas clouds in great explosions and get swept up in the creation of the next generation of stars. The process continues—new stars form from the accumulating gas and ash, die, and create more ash. As younger stars are created, the familiar spiral shape of our Galaxy—the Milky Way—takes form. The same thing is happening in similar patches of dark matter and gas peppered across the visible Universe.

  Nine billion years have passed since the Big Bang, and now a young star surrounded by planets, built from hydrogen and helium gas and the ash from dead stars, takes shape and ignites.