How Does the Universe Work?
from Through the Wormhole; Think of existence as an enormous web that we're all woven into, but we can't see the whole thing. There is so much we don't know about why the Universe functions the way it does. Science is our means to discover those rules, and so far we've revealed quite a few of them. Deep in the basement tunnels of Purdue University, scientists Jere Jenkins and Ephraim Fischbach have discovered that one of the supposedly unbreakable laws of physics is broken. Jenkins studies a powerful source of energy we can't see but is all around us radioactivity. Fischbach, a theoretical physicist, struggled with the huge implications of this finding. The idea that nuclear decays cannot be influenced by an external influence is so fundamental to so many aspects of quantum physics, nuclear physics, elementary-particle physics, that changing that would likely have a significant change on our understanding of the Universe, as well as on practical applications. The discharge of radioactive particles appears to change depending on how close the Earth is to the Sun. We're groping in the dark of the vast Universe, thinking we have uncovered its deepest truths, then finding we still have much to learn about the rules of nature. And nature does not make things easy for us. Down at the smallest scale of existence, deep in the weird world of quantum mechanics, it seems to play by two different rules at the same time. And the deeper we probe into its mysteries, the more we are forced to ask not just how the Universe works, but whether anything is real. Quantum mechanics has transformed the world. We owe most of our amazing technology to its explanations of how extremely small particles behave. But we don't really understand it. In the quantum world, nothing seems to make sense. Reality stops being real. This mystery is our greatest obstacle to unlocking the secrets of the Universe. If we can solve it, we may hold the keys to creation itself. Vienna, Austria, is arguably the birthplace of quantum mechanics. This is where you will find the leading quantum experimentalist in the world, professor Anton Zeilinger. When I first heard of quantum mechanics when I was a student, I was immediately struck by three things first, its unbelievable mathematical beauty. Secondly, by the incredible precision to which the predictions work. And thirdly, by the fact that it doesn't make sense. Quantum mechanics describes the behavior of all the tiny particles that everything is made of. This knowledge has given us computers, nuclear power, satellites, advanced medicine most of the great leaps forward humanity has taken in the past 100 years. But the quantum world seems to run contrary to everything we know about the laws of nature. Simply put, down where things are very, very small, the Universe follows a different set of rules. Consider the phenomenon of quantum nonlocality, when two tiny particles instantly share information across vast distances. Time and again Zeilinger has proven that no matter how extreme its predictions, quantum theory works even though it shouldn't. And perhaps the ultimate proof of just how unsettling quantum mechanics can be is something called the double-slit experiment. If the quantum theorists are correct, we will never understand the fundamental level of the Universe. Our hopes of finding an ultimate theory will fail, and the human race will hit a roadblock it can't break through. But what if they're wrong? What if the truth about what happens deep inside you, me, and everything else in the Universe is there if we're willing to look for it? For most of the 20th century, scientists believed quantum physics could not be explained, that we would just have to accept that we'll never know why things behave as they do down at the deepest levels of existence. But now a growing band of rebel scientists thinks there may be a logical explanation for quantum weirdness after all and new hope for revealing the ultimate truth of our Universe. The trail begins here with a drop of silicon. In his Paris laboratory, physicist Yves Couder and his team conduct an amazing series of experiments. They are observing the behavior of silicon droplets bouncing in lockstep on a vibrating plate. The mystery of quantum mechanics is, how can things like electrons sometimes behave like particles and sometimes behave like waves? Perhaps this is the answer. Antony Valentini of Clemson University is a quantum heretic. He loudly proclaims that physics went off the rails in the 1920s when it embraced the doctrine of quantum uncertainty, which says that nothing is real until we look at it. Valentini champions the theory that got left behind. It was created by one of the pillars of early 20th-century physics, Louis De Broglie. Louis De Broglie's original idea is an electron is both a wave and a particle all the time. The mere fact that there are different theories about what the answer might be doesn't mean that there's no answer. And eventually one of them is found to be the correct one. To understand how the Universe works, we need to unlock why the quantum world is so different from the world we know. It is an unsolved mystery that affects every single person on Earth, and this man thinks he can solve it. The more we understand the inner workings of the Universe, the more we humans are rewarded with new medicines, new technologies, and undreamed of improvements in our lives. But some say we're a long way off from unlocking the Universe's deepest secrets. We want definitive answers. What we have are mysteries upon mysteries. And one of the greatest mysteries is how the big stuff and the small stuff in the Universe fit together. Two well-tested theories describe how matter behaves relativity theory, which governs the physics of the large, and quantum theory, which describes the very small. If they were a couple, relativity would be a logical, pocket-protector-wearing engineer who strictly follows the speed limit of light. Quantum theory would be his volatile artist wife who seems to be everywhere at once. On paper, they don't get along. But in the real world, they are a happy pair. And like some real-life odd couples, no one understands why. The mystery boils down to gravity. Gravity dominates the world we know, and thanks to Newton and Einstein, we understand it pretty well. But physicists have no idea what role gravity plays in the quantum realm or its effect on space and time. If we crack this mystery, we will finally know if it is possible to travel back in time or through a wormhole. Petr Horava has a history of exploring the wild frontier of physics. Now he's tackling quantum gravity. So, how do you reconcile quantum mechanics and gravity? There are several different ways it can happen. Either quantum mechanics is stronger and wins and gravity has to be modified, or quantum mechanics has to be modified and gravity stays the same as in Einstein's general relativity. Petr feels the key is to watch how things change in scale between the upper layers of nature, where gravity holds sway, and the quantum layers down below. Nature organizes itself in layers of structure, and you see more and more layers as you zoom in and gain a better resolution of how you view the system. It's one of the most important theoretical concepts in modern physics. If space and time are unhinged, particles can't be in a specific place at a specific time. Hence, fuzziness and uncertainty. Unraveling the enigma of quantum gravity is a major hurdle in our quest to understand how the Universe works. But it shrinks against the magnitude of the biggest mystery facing humanity. 95% of the Universe is missing. This woman may know where and what it is. The more we peel away the layers of nature, the more we realize that something is missing something big. An enormous chunk of the Universe seems to be invisible. We can't see it, hear it, or detect it in any way. But if we want to unlock the secrets of the Universe, if we want to advance as a species, we have to find out what and where it is. The Universe began with the Big Bang, a shattering explosion of raw energy. That energy burst outward in a mass of superheated plasma. As it cooled, it began to clump together into all the material in the Universe the solids, liquids, and gases that everything is made of. To crack the cosmic code that underlies our Universe, we have to understand energy in all its forms. But what if almost 95% of the Universe is made of a form of energy we can't see and don't understand? These are the kinds of questions confronted daily in Geneva, Switzerland, the home of the world's largest particle accelerator the Large Hadron Collider and also hundreds of physicists. Clare Burrage is one of them, but she's hardly typical. Young, female, and an accomplished figure skater, Clare is trying to solve the vast mystery of the missing Universe. So, the energy from the Sun we know and we understand very well, but it seems like there's another form of energy out there in the Universe called dark energy that we don't understand at all. Accepted laws of physics dictate that the expansion of the Universe after the Big Bang should be slowing down. But recent astronomical observations have revealed that the expansion is rapidly speeding up. Some unexplained form of energy is pushing galaxies apart. So, at the moment, I'm moving forward even though I'm not doing anything because of the force of gravity. But if I were in space, where there are no forces acting on me, I shouldn't be moving at all. If I'm moving forwards, then there has to be something very strange acting on me, and this is what we call dark energy. How much of the Universe is dark energy? Put it this way. Here's the Universe: 4.6%, is all the matter we can see. Near-massless particles called neutrinos take up another 0.4%. We think that something called dark matter accounts for another 23%. Dark energy is the remaining 72% of the mass and energy of the Universe. We cannot see it, touch it, taste it, or detect it, but cosmologists are certain it is there. Without dark energy, gravity would cause the Universe to collapse in on itself. Clare suspects that dark energy is a by-product of a radical new piece of physics, an undiscovered particle called the chameleon. These mysterious particles actually carry an entirely different basic force than the four that physicists know about, a fifth fundamental force. When it is light, it can zip around much faster and become stronger. How heavy it is depends on its environment how much stuff is around it. So, here on Earth, there's a lot of stuff around, a lot of matter, and the chameleon becomes very heavy, very massive. It doesn't interact with the things around it very much, and that's why we don't see it in our everyday lives and in experiments here on Earth. But in intergalactic space, where there's almost nothing, the chameleon becomes very, very light, and it can interact with things over huge distances. And that's why it can drive the acceleration of the expansion of the Universe. This shape-shifting property explains why the chameleon has yet to be spotted in our particle accelerators. It should be everywhere inside you and me and far out in the cosmos. But how do we detect a master of disguise? The chameleon shows up in experiments on really tiny scales and on really huge scales. So you can look for it in the ways that particles behave in colliders on really tiny scales. But also, it affects the way that light travels, and so we can look on very large scales at how light from stars comes to us and whether we can see the effects of the chameleon there. Our slow and steady understanding of electromagnetism and the nuclear forces has transformed our lives, from electricity to telecommunications, transportation to warfare. What benefits could dark energy bring us? It's very hard to say now how a better understanding of dark energy is going to make people's lives better. But in the past, understanding things better has always led to benefits for mankind. In some ways, understanding dark energy, for understanding the Universe, it's more important than understanding the physics that we know here on Earth.
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