Results 1  10
of
49
Characterizing quantum theory in terms of informationtheoretic constraints
 Foundations of Physics
, 2003
"... We show that three fundamental informationtheoretic constraints—the impossibility of superluminal information transfer between two physical systems by performing measurements on one of them, the impossibility of broadcasting the information contained in an unknown physical state, and the impossibil ..."
Abstract

Cited by 28 (3 self)
 Add to MetaCart
We show that three fundamental informationtheoretic constraints—the impossibility of superluminal information transfer between two physical systems by performing measurements on one of them, the impossibility of broadcasting the information contained in an unknown physical state, and the impossibility of unconditionally secure bit commitment—suffice to entail that the observables and state space of a physical theory are quantummechanical. We demonstrate the converse derivation in part, and consider the implications of alternative answers to a remaining open question about nonlocality and bit commitment. KEY WORDS: quantum theory; informationtheoretic constraints. Of John Wheeler’s ‘‘Really Big Questions,’ ’ the one on which most progress has been made is It from Bit?—does information play a significant role at the foundations of physics? It is perhaps less ambitious than some of the other Questions, such as How Come Existence?, because it does not necessarily require a metaphysical answer. And unlike, say, Why the Quantum?, it does not require the discovery of new laws of nature: there was room for hope that it might be answered through a better understanding of the laws as we currently know them, particularly those of quantum physics. And this is what has happened: the better understanding is the quantum theory of information and computation. 1
Epistemic and Ontic Quantum Realities
, 2005
"... Quantum theory has provoked intense discussions about its interpretation since its pioneer days, beginning with Bohr’s view of quantum theory as a theory of knowledge. We show that such an epistemic perspective can be consistently complemented by Einstein’s ontically oriented position. ..."
Abstract

Cited by 21 (11 self)
 Add to MetaCart
Quantum theory has provoked intense discussions about its interpretation since its pioneer days, beginning with Bohr’s view of quantum theory as a theory of knowledge. We show that such an epistemic perspective can be consistently complemented by Einstein’s ontically oriented position.
The Bekenstein bound, topological quantum field theory and pluralistic quantum cosmology
"... this paper a new approach to the problem of constructing a quantum theory of gravity in the cosmological context is proposed. It is founded on results from four separate directions of investigation, which are: 1) A new point of view towards the interpretation problem in quantum cosmology[1, 2, 3, 4] ..."
Abstract

Cited by 19 (12 self)
 Add to MetaCart
this paper a new approach to the problem of constructing a quantum theory of gravity in the cosmological context is proposed. It is founded on results from four separate directions of investigation, which are: 1) A new point of view towards the interpretation problem in quantum cosmology[1, 2, 3, 4], which rejects the idea that a single quantum state, or a single Hilbert space, can provide a complete description of a closed system like the universe. Instead, the idea is to accept Bohr's original proposal that the quantum state requires for its interpretation a context in which we distinguish two subsystems of the universethe quantum system and observer. However, we seek to relativize this split, so that the boundary between the part of the universe that is considered the system and that which might be considered the observer may be chosen arbitrarily. The idea is then that a quantum theory of cosmology is specified by giving an assignment of a Hilbert space and algebra of observables to every possible boundary that can be considered to split the universe into two such subsystems. A quantum state of the universe is then an assignment of a statistical state to every one of these Hilbert spaces, subject to certain conditions of consistency. Each of these states is interpreted to contain the information that an observer on one side of each boundary might have about the system of the other side. This formulation then accepts the idea that each observer can only have incomplete information about the universe, so that the most complete description possible of the universe is given by the whole collection of incomplete, but mutually compatible quantum state descriptions of all the possible observers. At the same time, the information of different observers is, to some extent, ...
Bluff your way in the second law of thermodynamics
 STUD. HIST. PHIL. MOD. PHYS
, 2001
"... The aim of this article is to analyse the relation between the second law of thermodynamics and the socalled arrow of time. For this purpose, a number of different aspects in this arrow of time are distinguished, in particular those of time(a)symmetry and of (ir)reversibility. Next I review versio ..."
Abstract

Cited by 13 (2 self)
 Add to MetaCart
The aim of this article is to analyse the relation between the second law of thermodynamics and the socalled arrow of time. For this purpose, a number of different aspects in this arrow of time are distinguished, in particular those of time(a)symmetry and of (ir)reversibility. Next I review versions of the second law in the work of Carnot, Clausius, Kelvin, Planck, Gibbs, Carathéodory and Lieb and Yngvason, and investigate their connection with these aspects of the arrow of time. It is shown that this connection varies a great deal along with these formulations of the second law. According to the famous formulation by Planck, the second law expresses the irreversibility of natural processes. But in many other formulations irreversibility or even timeasymmetry plays no role. I therefore argue for the view that the second law has nothing to do with the arrow of time.
Geometrodynamics: spacetime or space
, 2004
"... To the memory of my Father, who taught me mathematics and much more. To Claire for her caring support, and to my Mother. To all my friends, with thanks. Yves, Becca, Suzy, Lynnette and Mark helped me survive my Cambridge years. Yves, Becca and Suzy have stayed in touch, while I often enjoyed Lynnett ..."
Abstract

Cited by 8 (8 self)
 Add to MetaCart
To the memory of my Father, who taught me mathematics and much more. To Claire for her caring support, and to my Mother. To all my friends, with thanks. Yves, Becca, Suzy, Lynnette and Mark helped me survive my Cambridge years. Yves, Becca and Suzy have stayed in touch, while I often enjoyed Lynnette and Chris’s company though my PhD years, and Mark was a familiar and welcome figure at QMUL. I also thank the good friends I made toward the end of my Cambridge years: Ed, Matt, Bjoern, Alex, Angela and Alison. And Bryony, for being a good friend during the difficult last year. Thanks also to all my other friends, office mates, and kind and entertaining people I have crossed paths with. To Professors Malcolm MacCallum and Reza Tavakol, with thanks for agreeing to supervise me, and for their encouragement and wisdom. I also thank Dr James Lidsey for supervision, and both Dr Lidsey and Professor Tavakol for active collaborations. I also thank Dr. Julian Barbour and Professor Niall Ó Murchadha for teaching me many things and for collaboration, and the Barbour family for much hospitality. I also thank Brendan Foster and Dr. Bryan Kelleher for many discussions and for collaboration, and Dr. Harvey Brown
The origins of timeasymmetry in thermodynamics: The minus first law
 Studies In History and Philosophy of Modern Physics
, 2001
"... This paper investigates what the source of timeasymmetry is in thermodynamics, and comments on the question whether a timesymmetric formulation of the Second Law is possible. ..."
Abstract

Cited by 6 (1 self)
 Add to MetaCart
This paper investigates what the source of timeasymmetry is in thermodynamics, and comments on the question whether a timesymmetric formulation of the Second Law is possible.
Quantum mechanics is about quantum information. Forthcoming
 in Foundations of Physics. quantph/0408020
"... I argue that quantum mechanics is fundamentally a theory about the representation and manipulation of information, not a theory about the mechanics of nonclassical waves or particles. The notion of quantum information is to be understood as a new physical primitive—just as, following Einstein’s spec ..."
Abstract

Cited by 5 (1 self)
 Add to MetaCart
I argue that quantum mechanics is fundamentally a theory about the representation and manipulation of information, not a theory about the mechanics of nonclassical waves or particles. The notion of quantum information is to be understood as a new physical primitive—just as, following Einstein’s special theory of relativity, a field is no longer regarded as the physical manifestation of vibrations in a mechanical medium, but recognized as a new physical primitive in its own right. 1
Boltzmann and Statistical Mechanics
, 1996
"... “O! immodest mortal! Your destiny is the joy of watching the evershifting battle!” Ludwig Boltzmann 1 1 ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
“O! immodest mortal! Your destiny is the joy of watching the evershifting battle!” Ludwig Boltzmann 1 1
Quantum information and computation
 arXiv:quantph/0512125. Forthcoming in Butterfield and Earman (eds.) Handbook of Philosophy of Physics
, 2005
"... This Chapter deals with theoretical developments in the subject of quantum information and quantum computation, and includes an overview of classical information and some relevant quantum mechanics. The discussion covers topics in quantum communication, quantum cryptography, and quantum computation, ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
This Chapter deals with theoretical developments in the subject of quantum information and quantum computation, and includes an overview of classical information and some relevant quantum mechanics. The discussion covers topics in quantum communication, quantum cryptography, and quantum computation, and concludes by considering whether a perspective in terms of quantum information
When champions meet: Rethinking the Bohr–Einstein debate
, 2006
"... Einstein’s philosophy of physics (as clarified by Fine and Howard) was predicated on his Trennungsprinzip, a combination of separability and locality, without which he believed “physical thought ” and “physical laws ” to be impossible. Bohr’s philosophy (as elucidated by Hooker, Scheibe, Folse, Howa ..."
Abstract

Cited by 4 (1 self)
 Add to MetaCart
Einstein’s philosophy of physics (as clarified by Fine and Howard) was predicated on his Trennungsprinzip, a combination of separability and locality, without which he believed “physical thought ” and “physical laws ” to be impossible. Bohr’s philosophy (as elucidated by Hooker, Scheibe, Folse, Howard, and others), on the other hand, was grounded in a seemingly different doctrine about the possibility of objective knowledge, namely the necessity of classical concepts. In fact, it follows from Raggio’s Theorem in algebraic quantum theory that within a suitable class of physical theories Einstein’s doctrine is mathematically equivalent to Bohr’s, so that quantum mechanics accommodates Einstein’s Trennungsprinzip if and only if it is interpreted à la Bohr through classical physics. Unfortunately, the protagonists themselves failed to discuss their differences in a constructive way, since in its early phase their debate was blurred by an undue emphasis on the uncertainty relations, whereas in its second stage it was dominated by Einstein’s flawed attempts to establish the “incompleteness ” of quantum mechanics. These two aspects of their debate may still be understood and appreciated, however, as reflecting a much deeper and insurmountable disagreement between Bohr and Einstein on the knowability of Nature. Using the theological controversy on the knowability of God as a analogy, Einstein was a Spinozist, whereas Bohr could be said to be on the side of Maimonides. Thus Einstein’s offthecuff characterization of Bohr as a ‘Talmudic philosopher ’ was spoton.