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mysteries |
Parallel Universes |
Other Information |
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| Some scientists now believe the universe
co-exists with an infinite number of others.
In his basement, US college student Quinn Mallory has built a machine that is capable of taking him on an unprecedented journey. When he starts it up, the device opens a tunnel in the fabric of space-time, through which Mallory can pass. When he emerges at the other end, Mallory finds himself in an almost identical town... but in another universe. Quinn Mallory is a fictional character, whose universe-hopping machine is the premise of the television series Sliders. But Mallory's fantastic journeys do, in fact, draw on real scientific theory - the so-called 'parallel universes' hypothesis. This controversial idea was developed in an attempt to solve some recurring problems in theoretical physics. If the theory is correct - and there is nothing in the maths underlying the modern physics that makes it impossible - then journeys between these putative universes may also be a possibility. The theory of parallel universes was first introduced in 1957 by Hugh Everett III at Princeton University, US. He saw the idea as the only way to resolve various paradoxes central to quantum theory, one of the twin pillars of modern physics. Developed in the early part of the last century by pioneering physicists in several countries, quantum theory is a very effective way of describing and predicting the behaviour of matter on the smallest scale, including molecules, atoms and subatomic particles. Huge Discovery. In 1926, the brilliant Austrian physicist Erwin Schrodinger discovered one of the central features of quantum theory: the wave function. Every particle has its own wave function - a mathematical equation describing all possible states of that particle. The wave functions of electrons in atoms, for example, allow a physicist to work out the electron's energies or positions with incredible accuracy. The mathematics of quantum physics in general - and the wave function in particular - describe the world so accurately that the validity of the theory cannot really be questioned. At the same time, however, the theory throws up several bizarre paradoxes, forcing physicists to become philosophers, questioning the very existence of reality itself. It turns out, for example, that the wave function is not just a way to describe all the possible states of a particle; the particle must exist in all of those states simultaneously. This means that it can literally be in two places at once, a conclusion that both defied common sense and experience. But the parallel universes theory can resolve these paradoxes. Whenever a number of different possibilities for a system are described by a wave function, the theory goes, they do all exist, but the universe splits over and over again, so that each possibility comes to exist in a different universe. This means that, over time, the number of universes must be phenomenally large. In fact, parallel universe theory predicts that there is an infinite number of universes, which together accommodate all the possible states of all the possible particles in existence. One way to look at the theory of parallel universes is to imagine that the universe itself has a wave function, so the universe we inhabit is just one of the myriad possible states of this ultimate universe. Some parallel universes will be similar to our own, while others will be very different. So, that is how the theory arose: but can it be possible? Recent polls of leading theoretical physicists consistently show that, publicly or privately, more than half of them are prepared to entertain the possibility that parallel universes exist. This begs the question: could it be possible to travel or communicate between these universes? At first sight, such contact seems impossible, as the different universes exist within different dimensions of space and time. In the 1960's, however, possible mechanism for communication and travel was suggested. The key to this exiting development was the other pillar of modern physics, Albert Einstein's famous theory of general relativity. 'Curving' Space-Time. According to this theory, space-time - Einstein's 'fourth dimension' - can be 'curved' by any object with mass. A huge object such as a star, curves space-time a great deal. When a star collapses at the end of its life, gravity pulls the matter of which it is made inwards, condensing it into a relatively small space, and massively increasing its density to unimaginable values, which cause space-time to curve around it. When the dense mass has generated a gravitational field so intense that even light cannot escape, the star becomes a black hole. Many physicists have suggested that the anomalies these create in the fabric of space-time could provide us with doorways into parallel universes. Such travel might be achieved by passing through wormholes - 'tunnels' in space-time joining two black holes in different universes. Although no such wormhole has yet been discovered, when their existence was first mooted it was believed that the intense forces held within black holes would obliterate any would-be traveler. However, several well-respected theorists now suggest such a journey could be made safely if the black hole were rotating. Split Personalities? The existence of parallel universes also has profound personal implications. If the hypothesis is true, there are an infinite number of copies of everyone now living, each inhabiting a different universe. Anything that is possible must exist somewhere. The natural corollary of this idea is that whenever we make a decision, we effectively choose the path of the universe in which we live, while, in parallel universes, different versions of reality unfold. In some universes each and every one of us is Prime Minister or President, and in others there is no government at all because the world has been thrust into a nuclear winter. One day it might be possible to interact with the other versions of ourselves, and discover what might have happened to us had we made different choices in our early life. In some respects, the theory gives us an awesome responsibility, as we all continually create the universe in which we live. And what of the versions of you that live in other universes - are they more or less 'you', and what implications does that have for ideas such as identity, the soul, and consciousness? The parallel universes hypothesis begs questions of philosophers and theologians as well as physicists. Time Travel. It has also been suggested that wormholes could enable us to travel through time as well as space. It may be possible to travel to an earlier time in another universe, or indeed in our own. One paradox normally associated with time travel is often called the 'Grandmother Paradox'. This poses the question of what happens if someone travels back in time and somehow causes the death of his grandmother when she was a a child. This would mean the traveler would never have been born and so could not travel back to kill his grandmother. Parallel universes can resolve this paradox. If new universes are continually generated each time a new choice is made, the past of our own universe is shared by countless others. If it is possible for someone to travel into the past and shoot his grandmother, the event would necessarily end in the creation of a parallel universe. And that is where the homicidal time-traveler would have gone, affecting the present in a universe other than his own. The Burning Question. One question has to be asked about parallel universes: exactly where are they? The answer to that is that they exist in other dimensions. The other universes may exist in a way similar to bubbles floating around freely. However it has also been suggested that the universes are literally right next to each other, separated from ours by less than an atom, and bizarrely the mathematicians say that this is the most likely, and the further away the universe is situated from ours the more different it gets. |
Sources: The X Factor By: Joseph Minter |