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Download Schrödinger's Rabbits: The Many Worlds of Quantum ePub

by Colin Bruce

Download Schrödinger's Rabbits: The Many Worlds of Quantum ePub
  • ISBN 0309097401
  • ISBN13 978-0309097406
  • Language English
  • Author Colin Bruce
  • Publisher Joseph Henry Press (October 13, 2004)
  • Pages 282
  • Formats mobi rtf txt docx
  • Category Math
  • Subcategory Physics
  • Size ePub 1507 kb
  • Size Fb2 1196 kb
  • Rating: 4.9
  • Votes: 894

For the better part of a century, attempts to explain what was really going on in the quantum world seemed doomed to failure. But recent technological advances have made the question both practical and urgent. A brilliantly imaginative group of physicists at Oxford University have risen to the challenge. This is their story.

At long last, there is a sensible way to think about quantum mechanics. The new view abolishes the need to believe in randomness, long-range spooky forces, or conscious observers with mysterious powers to collapse cats into a state of life or death. But the new understanding comes at a price: we must accept that we live in a multiverse wherein countless versions of reality unfold side-by-side. The philosophical and personal consequences of this are awe-inspiring.

The new interpretation has allowed imaginative physicists to conceive of wonderful new technologies: measuring devices that effectively share information between worlds and computers that can borrow the power of other worlds to perform calculations. Step by step, the problems initially associated with the original many-worlds formulation have been addressed and answered so that a clear but startling new picture has emerged.

Just as Copenhagen was the centre of quantum discussion a lifetime ago, so Oxford has been the epicenter of the modern debate, with such figures as Roger Penrose and Anton Zeilinger fighting for single-world views, and David Deutsch, Lev Vaidman and a host of others for many-worlds.

An independent physicist living in Oxford, Bruce has had a ringside seat to the debate. In his capable hands, we understand why the initially fantastic sounding many-worlds view is not only a useful way to look at things, but logically compelling. Parallel worlds are as real as the distant galaxies detected by the Hubble Space Telescope, even though the evidence for their existence may consist only of a few photons.


Schrödinger's Rabbits: The Many Worlds of Quantum.

March 31, 2006, Joseph Henry Press. Paperback in English. Libraries near you: WorldCat.

A magical universe Clinging to the classical Collapse by inference A horror story writ large The Old Testament Let's all move into Hilbert space Pick your own universe A desirable locality Introducing many-worlds Harnessing many-worlds 1 : impossible measurements Harnessing many-worlds 2 : impossible computers Many-worlds heroes and dragons The terror of many-worlds The classical warrior: Roger Penrose The. new age warrior: Anton Zeilinger Proving and improving many-worlds. Rubrics: Quantum theory Popular works.

At long last, there is a sensible way to think about quantum mechanics. The new view abolishes the need to believe in randomness, long-range spooky forces, or conscious observers with mysterious powers to collapse cats into a state of life or death

At long last, there is a sensible way to think about quantum mechanics. The new view abolishes the need to believe in randomness, long-range spooky forces, or conscious observers with mysterious powers to collapse cats into a state of life or death. But the new understanding comes at a price: we must accept that we live in a multiverse wherein countless versions of reality unfold side-by-side. The philosophical and personal consequences of this are awe-inspiring

By Colin Bruce Just as Copenhagen was once the centre of quantum dialogue a life-time in the past, so Oxford has been the epicenter of the trendy debate, with such figures as Roger Penrose.

For the higher a part of a century, makes an attempt to give an explanation for what used to be rather occurring within the quantum international appeared doomed to failure. yet fresh technological advances have made the query either sensible and pressing. Just as Copenhagen was once the centre of quantum dialogue a life-time in the past, so Oxford has been the epicenter of the trendy debate, with such figures as Roger Penrose and Anton Zeilinger combating for single-world perspectives, and David Deutsch, Lev Vaidman and a bunch of others for many-worlds.

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Colin Bootman - The Steel Pan Man of Harlem (Carolrhoda Picture Books). Colin Bruce - Schrödinger's Rabbits: The Many Worlds of Quantum. Читать pdf. Colin Bruce - Schrodinger's Rabbits: Entering The Many Worlds Of Quantum. The philosophical and personal consequences of this are awe-inspiring.

Manufacturer: National Academies Press Release date: 13 October 2004 ISBN-10 : 0309097401 ISBN-13: 9780309097406.

Colin Bruce is a British author and physicist. He has written many scientific works, including non-fiction, but he is most well known for his popular science stories. Schrodinger's Rabbits: The Many Worlds of Quantum. He is an expert in mathematical paradoxes and a lover of mysteries YouTube Encyclopedic.

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Talk about Schrödinger's Rabbits: The Many Worlds of Quantum


Clodebd
I give this book four stars, in spite of significant conceptual errors, because it clearly explains not only the "many worlds interpretation" but also what an interpretation is and how to choose a good one.

Quantum mechanics has often been "interpreted" by use of approximations. The many worlds view leads to these same approximations but also accepts the whole mathematical theory at face value. So it works also in cases like Einstein's EPR problem. This is actually a very old approach, but it has been waiting for a clear relatively easy to understand explanation, like this book, to become generally accepted.

An example of an error: p. 127, "The mathematics of ''decoherence'' tell us that the interference between developing outcomes that are significantly different above the microscopic level fade very rapidly." This statistical and partly classical view is not needed here. The lack of visibility of alternate outcomes follows from the linearity of the Schrodinger equation. It was explained by Everett, in a footnote to his thesis, "The whole question of the transition from the 'possible' to the 'actual' is taken care of by the theory in a very simple way--there is no such transition, nor is such a transition necessary for the theory to be in accord with our experience. From the viewpoint of the theory, all elements of a superposition (all branches) are 'actual,' none more 'real' than the rest. It is unnecessary to suppose that all but one are somehow destroyed, since all the separate elements of a superposition individually obey the wave equation with complete indifference to the presence or absence of ('actuality' or not) of any other elements. This total lack of effect of one branch on another also implies that no observer will ever be aware of any 'splitting' process.", H. Everett, "Relative State Formulation of Quantum Mechanics", Rev. Mod. Phys. 29, 454-62, (1957)

Some quantum applications can be explained by the Copenhagen Interpretation, but, the author argues, were easier to think of in the Many Worlds interpretation. There may be others, that like EPR, might actually work, but would appear impossible in the Copenhagen Interpretation.
Tori Texer
In the nineteenth and early twentieth centuries, many natural philosophers believed that the laws of the Universe could be derived from Reason. For instance, Galilean invariance gave us Newton's Laws, and similar invariance conditions give rise to special and general relativity. Quantum mechanics changed all that because many quantum mechanical phenomena violate one or more 'reasonable' assumptions, such as the impossibility of action at a distance. This is really why Einstein never accepted quantum mechanics as more than a provisional theory.

It is tempting to be dismissive of quantum mechanics because it only deals with phenomena at extremely sub-microscopic dimensions, and classical mechanics and electrodynamics can get alone without it perfectly well at 'human' dimensions. Both reasons are faulty. First, quantum mechanics explains quantum tunneling, which is central to solid state devices such as transistors, and more generally, quantum effects can be amplified without difficulty to the human level (this is the famous Schrödinger's Cat problem, to which the title of the book alludes. Second, there are deep antinomies in classical electromagnetic theory, including the prediction that the energy in blackbody radiation goes to infinity as the wavelength of the energy goes to zero.

There are many strange and beautiful quantum phenomena. Perhaps the two most famous are wave/particle duality and entanglement. Wave-particle duality is well illustrated by the famous two-slit experiment. Photons are directed towards an absorbing wall with two vertical slits some macroscopic distant apart. The few photons that go through one of the slits hit a clear photographic film that records the absorption of the photon by coloring the impact point black. If photons are particles, there should be two widely separated masses of black dots whose location can be calculated using simple geometry. If photons are waves (like waves in a pond), it is not hard to show that there should be alternating bands of light and dark on the photographic plate, corresponding the interference pattern of the two parts of the wave that pass through the distinct slits. If you do this experiment, photons act wave-like. However, if you measure the passage of the photon through a slit, you always find it went through either one or the other, but not partly through both. This shows the photon is a particle. Moreover, if you can measure which slit the photon went through, the interference patter on the plate disappears, and the photon leave a black spot on the plate.

Early interpreters of this weir phenomenon argued that by measuring the photon, you interfered with its normal path, as explained by classical signaling theory, so the phenomenon is just poor experimental design. For a variety of reasons that you can read about, this explanation is faulty. The widely accepted explanation (the so-called Copenhagen theory, named after Neils Bohr) is that the photon is indeed a wave, as described by Schrödinger's famous equation or Planck's relativistic version. These equations describe not where the photon is, but rather a probability distribution over its possible locations. When observed, the wave 'collapses' to a particular location, the location being proportion to its relative probability.

This experiment and its interpretation calls into question the nature of objectivity and subjectivity in a highly radical form. What does it mean to be 'observed'? By whom? What if it is 'observed' by a machine and you do not have access to the machine's memory? The two-slit and related experiments, as explained by the Copenhagen school, simply divides reality in to nature plus observer, where observer means a human or an instrument that can be read and recorded, accessible to a human. This is fine for all practical purposes, because that's how we humans do science. But its ontological status is highly compromised.

A second weird phenomenon involves 'entanglement.' Electrons have 'spin,' which when measured in any direction, is either 'up' or 'down.' When electrons are generated in pairs, they may be entangled in the sense that after they are separated, if one measures 'up' in a particular direction, the other must measure 'down.' However the state of spin is a probability distribution that collapses to a particular up or down when you measure it. Suppose the entangled electrons move apart until they are a light-second apart, and then the spin of one is measured in some direction. Then immediately, not a second later, the other measures the opposite direction. This is not a relativistic time effect, and it has been repeatedly verified in the laboratory. It is called a violation of locality.

Einstein and his colleagues Podolsky and Rosen (1935) used a similar argument to show that there must be something wrong with quantum mechanics, but it turns out that that is just the way the world works, like it or not.

Most physicists do not care why quantum mechanics works the way it does, but some do, and many of those think that there must be a better model that the Copenhagen collapse theory. One is the Many Worlds Interpretation (MMI), which Bruce explains and defends in this book. The MMI says that whenever there appears to be a collapse of the quantum wave, the Universe really branches into a large number of alternative Universes, side-by-side, each of which captures one of the possible states. So, for instance, if you set up an apparatus that kills you if a certain photon is measured as having spin up, and does nothing if the spin is down. Then the whole Universe splits into two Universes, in the first of which you are alive and the other of which you are dead.

This theory does explain most of the queerness of quantum mechanics, and it could be true. But there is no evidence that it is true. Nor has anyone ever suggested an experiment that would determine its truth value (Bruce suggests some possibilities, but they are far-fetched). Moreover, the theory itself is completely outlandish, far weirder than the phenomenon it is supposed to explain. The fact is that reading this and other attempts to explain quantum weirdness are fun and challenging intellectually, but their real value is virtually zero. When someone tells me he believes a version of the MWI, I treat the person the same as if they told me they believed in transubstantiation or the tooth fairy.

Nevertheless, quantum mechanics is certainly not a "true" theory, if only because it makes no room for gravity. The string and quantum gravity theorists attempt to repair this fault, but they produce theories that are as yet untested, although possibly testable.

But I think there is a deeper problem. Quantum mechanics represents a particle (e.g., a photon) as a point in Hilbert space, which is an infinite dimensional vector space. I don't believe there are `real' infinities, and hence this representation must be an approximation of the true, finite, model. We should be looking at finite or countable models of particle physics, not hugely overpopulated continuous models. Richard Feynman registered his discomfort with nonconstructible, continuous models, in the following words (quoted by Bruce, p. 242): "It always bothers me that, according to the laws as we understand them today, it takes a computing machine an infinite number of operations to figure out what goes on in no matter how tiny a region of space, and no matter how tiny a region of time..." I have often make the hypothesis that ultimately physics will not require a mathematical statement, that in the end the machinery will be revealed, and the laws will turn out to be simple, like the checkerboard with all its apparent complexities."

I realize many readers will not share my skepticism concerning infinite models. But they should, because it is the only reasonable position. Countable models are fine, because we can attain any element of a countable model in finite time. But uncountable models are just a useful human construct, probably not corresponding to anything real in the world. At any rate, reading Bruce's book conjures up all sorts of cute ideas that are fun to think about while taking a break from the real world.