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11
NonTuring Computers and NonTuring Computability
, 1994
"... possible to perform computational supertasks — that is, an infinite number of computational steps in a finite span of time — in a kind of relativistic spacetime that Earman and Norton (1993) have dubbed a MalamentHogarth spacetime1. ..."
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Cited by 36 (2 self)
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possible to perform computational supertasks — that is, an infinite number of computational steps in a finite span of time — in a kind of relativistic spacetime that Earman and Norton (1993) have dubbed a MalamentHogarth spacetime1.
Physical Hypercomputation and the Church–Turing Thesis
, 2003
"... We describe a possible physical device that computes a function that cannot be computed by a Turing machine. The device is physical in the sense that it is compatible with General Relativity. We discuss some objections, focusing on those which deny that the device is either a computer or computes a ..."
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Cited by 13 (0 self)
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We describe a possible physical device that computes a function that cannot be computed by a Turing machine. The device is physical in the sense that it is compatible with General Relativity. We discuss some objections, focusing on those which deny that the device is either a computer or computes a function that is not Turing computable. Finally, we argue that the existence of the device does not refute the Church–Turing thesis, but nevertheless may be a counterexample to Gandy’s thesis.
Quantum SpeedUp of Computations
 Philosophy of Science
, 2002
"... ChurchTuring Thesis as saying something about the scope and limitations of physical computing machines. Although this was not the intention of Church or Turing, the Physical Church Turing thesis is interesting in its own right. Consider, for example, Wolfram’s formulation: One can expect in fact th ..."
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ChurchTuring Thesis as saying something about the scope and limitations of physical computing machines. Although this was not the intention of Church or Turing, the Physical Church Turing thesis is interesting in its own right. Consider, for example, Wolfram’s formulation: One can expect in fact that universal computers are as powerful in their computational capabilities as any physically realizable system can be, that they can simulate any physical system...Nophysically implementable procedure could then shortcut a computationally irreducible process. (Wolfram 1985) Wolfram’s thesis consists of two parts: (a) Any physical system can be simulated (to any degree of approximation) by a universal Turing machine (b) Complexity bounds on Turing machine simulations have physical significance. For example, suppose that the computation of the minimum energy of some system of n particles takes at least exponentially (in n) many steps. Then the relaxation time of the actual physical system to its minimum energy state will also take exponential time. An even more extreme formulation of (more or less) the same thesis is due to Aharonov (1998): A probabilistic Turing machine can simulate any reasonable physical device in polynomial cost. She calls this The Modern Church Thesis. Aharonov refers here to probabilistic Turing machines that use random numbers in addition to the usual deterministic table of steps. It seems that such machines are capable to perform certain tasks faster than fully deterministic machines. The most famous randomized algorithm of that kind concerns the decision whether a given natural number is prime. A probabilistic algorithm that decides primality in a number of
ZENO MEETS MODERN SCIENCE
, 2005
"... “No one has ever touched Zeno without refuting him”. We will not refute Zeno in this paper. Instead we review some unexpected encounters of Zeno with modern science. The paper begins with a brief biography of Zeno of Elea followed by his famous paradoxes of motion. Reflections on continuity of space ..."
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“No one has ever touched Zeno without refuting him”. We will not refute Zeno in this paper. Instead we review some unexpected encounters of Zeno with modern science. The paper begins with a brief biography of Zeno of Elea followed by his famous paradoxes of motion. Reflections on continuity of space and time lead us to Banach and Tarski and to their celebrated paradox, which is in fact not a paradox at all but a strict mathematical theorem, although very counterintuitive. Quantum mechanics brings another flavour in Zeno paradoxes. Quantum Zeno and antiZeno effects are really paradoxical but now experimental facts. Then we discuss supertasks and bifurcated supertasks. The concept of localisation leads us to Newton and Wigner and to interesting phenomenon of quantum revivals. At last we note that the paradoxical idea of timeless universe, defended by Zeno and Parmenides at ancient times, is still alive in quantum gravity. The list of references that follows is necessarily incomplete but we hope it will assist interested reader to fill in details. PACS numbers: 01.70.+w 1.
Quantum Hypercomputation—Hype or Computation?
, 2007
"... A recent attempt to compute a (recursion–theoretic) non–computable function using the quantum adiabatic algorithm is criticized and found wanting. Quantum algorithms may outperform classical algorithms in some cases, but so far they retain the classical (recursion–theoretic) notion of computability. ..."
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A recent attempt to compute a (recursion–theoretic) non–computable function using the quantum adiabatic algorithm is criticized and found wanting. Quantum algorithms may outperform classical algorithms in some cases, but so far they retain the classical (recursion–theoretic) notion of computability. A speculation is then offered as to where the putative power of quantum computers may come from.
American Philosophical Quarterly 36/4 (October 1999): 309321 BLANKS: SIGNS OF OMISSION
"... The notes I handle no better than many pianists. But the pauses between the notes ah, that is where the art resides. " Artur Schabel `Antidisestablishmentarianism ' is the longest word. But what is longest possible word? And what is the shortest possible word? Reflection on these questi ..."
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The notes I handle no better than many pianists. But the pauses between the notes ah, that is where the art resides. &quot; Artur Schabel `Antidisestablishmentarianism ' is the longest word. But what is longest possible word? And what is the shortest possible word? Reflection on these questions have prompted me write the longest essay that has ever been written. This is it. So, sit back. Nothing will ever be longer because this one contains infinitely many sentences. Word length = ∞?This may seem impossible. Only finitely many symbols can be inscribed on a page. Even if I wrote smaller and smaller, I would eventually run out of inscribable surfaces. I cannot autograph an atom. Even if I had unlimited time, I would run out of space. I appear condemned to produce only finitely many sentences.
Quantum gravity computers: On the
, 2008
"... theory of computation with indefinite causal structure ..."
EXTENDING CANTOR’S PARADOX A CRITIQUE OF INFINITY AND SELFREFERENCE
, 809
"... Abstract. This paper examines infinity and selfreference from a critique perspective. Starting from an extension of Cantor Paradox that suggests the inconsistency of the actual infinite, the paper makes a short review of the controversial history of infinity and suggests several indicators of its i ..."
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Abstract. This paper examines infinity and selfreference from a critique perspective. Starting from an extension of Cantor Paradox that suggests the inconsistency of the actual infinite, the paper makes a short review of the controversial history of infinity and suggests several indicators of its inconsistency. Semantic selfreference is also examined from the same critique perspective by comparing it with selfreferent sets. The platonic scenario of infinity and selfreference is finally criticized from a biological and neurobiological perspective. 1.
THE ALEPHZERO OR ZERO DICHOTOMY (New and extended version with new arguments)
, 804
"... Abstract. This paper proves the existence of a dichotomy which being formally derived from the topological successiveness of ω ∗order leads to the same absurdity of Zeno’s Dichotomy II. It also derives a contradictory result from the first Zeno’s Dichotomy. ..."
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Abstract. This paper proves the existence of a dichotomy which being formally derived from the topological successiveness of ω ∗order leads to the same absurdity of Zeno’s Dichotomy II. It also derives a contradictory result from the first Zeno’s Dichotomy.