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A perpetual motion machine is not simply an object that moves forever once set into motion: it must also generate some useful sort of motion. If this device could exist, it would produce energy out of no energy. It could be harnessed to make your car run forever without using fuel of any sort. Any sequence of transformations turning something without energy into something with energy, without depleting any energy supply, is impossible in our universe: it could not be made to happen, because of a fundamental law that physicists call the principle of conservation of energy.
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As I shall explain in this book, some of these things, such as information, heat, and work, already have some explanation in physics, but it is insufficient: it is only approximate, unlike more fundamental theories of physics, such as quantum theory and general relativity. Some others, such as kn...
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In certain areas, it is no longer the case. The assumption that all fundamental explanations in science must be expressed only in terms of what happens, with little or no reference to counterfactuals, is now getting in the way of progress. For counterfactuals are essential to a number of things ...
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"If you could soar high in the sky, as red kites often do in search of prey, and look down at the domain of all things known and yet to be known, you would see something very curious: a vast class of things that science has so far almost entirely neglected. These things are central to our underst...
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Things that have not happened -- but could happen -- are the things that constitute the world of counterfactuals, a neglected area of scientific theory.
A luminous guide to how the radical new science of counterfactuals can reveal the full scope of our ...
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The computer may never be so programmed; but the fact that it could is an essential fact about it, without which it would not qualify as a computer. The counterfactuals that matter to science and physics, so far neglected, are facts about what could or could not be made to happen to physical syst...
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"Another significant counterfactual property of physical systems, central to thermodynamics, is that a steam engine is possible. A steam engine is a device that transforms energy of one sort into energy of a different sort, and it can perform useful tasks, such as moving a piston, without ever v...
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More generally, you can't explain the presence of a lifeboat aboard a pirate ship only in terms of an actual shipwreck. Everyone knows that the lifeboat is there because of a shipwreck that could happen (a counterfactual explanation). And that would still be the reason even if the ship never did ...
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The box may be never found; and laden with significance. It would signify, for instance, that a civilization visited the planet, and much about its degree of sophistication. To further grasp the importance of counterfactual properties, and their difference from actual properties, imagine a comput...
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They are facts not about what is -- the 'actual' -- but about what could or could not be. In order to distinguish them from the actual, they are called counterfactuals. Suppose that some future space mission visited a remote planet in another solar system left a stainless-steel box containing am...
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The fundamental types of counterfactuals that occur in physics are of two kinds: one is the impossibility of performing a transformation (building a perpetual motion machine); the other is the possibility of performing a transformation (building a steam engine). Both are cardinal properties of th...
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An object in motion will stay in motion unless something pushes or pulls on it.
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Moreover, energy is something that cannot be created not destroyed, it simply is. Energy can change forms and is als...
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