Dennis Dieks | Utrecht University (original) (raw)
Papers by Dennis Dieks
Foundations of Physics
The theories of pre-quantum physics are standardly seen as representing physical systems and thei... more The theories of pre-quantum physics are standardly seen as representing physical systems and their properties. Quantum mechanics in its standard form is a more problematic case: here, interpretational problems have led to doubts about the tenability of realist views. Thus, QBists and Quantum Pragmatists maintain that quantum mechanics should not be thought of as representing physical systems, but rather as an agent-centered tool for updating beliefs about such systems. It is part and parcel of such views that different agents may have different beliefs and may assign different quantum states. What results is a collection of agent-centered perspectives rather than a unique representation of the physical world. In this paper we argue that the problems identified by QBism and Quantum Pragmatism do not necessitate abandoning the ideal of representing the physical world. We can avail ourselves of the same puzzle-solving strategies as employed by QBists and pragmatists by adopting a persp...
What is Quantum Information?
Fundamental Theories of Physics, 2020
Hermann Weyl connected his epoch-making work on general relativity and gauge theory to his Husser... more Hermann Weyl connected his epoch-making work on general relativity and gauge theory to his Husserlian views about the phenomenological essence of space and time. This philosophical stance of Weyl's has received considerable attention in recent years and has been favorably compared and contrasted with the "logicalempiricist" approach of Reichenbach, Weyl's contemporary who wrote extensively about relativity and the philosophy of space and time. We will argue, however, that Weyl's use of phenomenology should be seen as a case of personal heuristics rather than as a systematic and viable philosophy of physics. We will explain and defend Reichenbach's sophisticated empiricism, which in our opinion has often been misunderstood, and argue that it is better suited as a general philosophical framework for the natural sciences than Weyl's phenomenology. In the second half of the nineteenth and the beginning of the twentieth century Kant's original version of this "synthetic a priori" doctrine came under increasing
arXiv: History and Philosophy of Physics, 2018
In his Autobiographical Notes, Einstein mentioned that on his road to the final theory of general... more In his Autobiographical Notes, Einstein mentioned that on his road to the final theory of general relativity it was a major difficulty to accustom himself to the idea that coordinates need not possess an immediate physical meaning in terms of lengths and times. This appears strange: that coordinates are conventional markers of events seems an obvious fact, already familiar from pre-relativistic physics. In this paper we explore the background of Einsteins difficulties, going from his 1905 paper on special relativity, through his 1907 and 1911 papers on the consequences of the equivalence principle, to the 1916 review paper on the general theory. As we shall argue, Einstein's problems were intimately connected to his early methodology, in which clarity achieved by concrete physical pictures played an essential role; and to the related fact that on his route to the general theory he focused on special situations that were easily accessible to physical intuition. The details of thi...
European Studies in Philosophy of Science, 2019
The Scientific Revolution is often associated with a transition to a “mechanistic” world view. Ho... more The Scientific Revolution is often associated with a transition to a “mechanistic” world view. However, “mechanization” is not the term that best captures the distinctive nature of modern physics: “mathematization” would be a better characterization. Modern physics attempts to find mathematical relations between quantities, and does not require that these relations be interpreted in terms of mechanisms. Moreover, in modern physics there are cases in which it is unnatural to give the mathematical formalism a mechanistic interpretation, even if “mechanistic” is broadly construed. Both on the level of ontology and that of explanation physics turns out to be more general and liberal than what is suggested by the catchphrase that physics explains by identifying mechanisms. Although mechanistic explanation remains an important conceptual tool, in particular for achieving understanding, it is not the only one available and cannot lay claim to fundamentality.
The peculiarities of rotating frames of reference played an important role in the genesis of gene... more The peculiarities of rotating frames of reference played an important role in the genesis of general relativity. Considering them, Einstein became convinced that coordinates have a different status in the general theory of relativity than in the special theory. This line of thinking was confused, however. To clarify the situation we investigate the relation between coordinates and the results of space-time measurements in rotating reference frames. We argue that the difference between rotating systems (or accelerating systems in general) and inertial systems does not lie in a different status of the coordinates (which are conventional in all cases), but rather in different global chronogeometric properties of the various reference frames. In the course of our discussion we comment on a number of related issues, such as the question of whether a consideration of the behavior of rods and clocks is indispensable for the foundation of kinematics, the influence of acceleration on the beh...
Quantum Worlds, 2019
Experimental evidence of the last decades has made the status of "collapses of the wave function"... more Experimental evidence of the last decades has made the status of "collapses of the wave function" even more shaky than it already was on conceptual grounds: interference effects turn out to be detectable even when collapses are typically expected to occur. Non-collapse interpretations should consequently be taken seriously. In this paper we argue that such interpretations suggest a perspectivalism according to which quantum objects are not characterized by monadic properties, but by relations to other systems. Accordingly, physical systems may possess different properties with respect to different "reference systems". We discuss some of the relevant arguments, and argue that perspectivalism both evades recent arguments that single-world interpretations are inconsistent and eliminates the need for a privileged rest frame in the relativistic case.
European Studies in Philosophy of Science, 2019
Varieties of Scientific Realism, 2017
Underdetermination of theories by empirical data is a central theme in debates surrounding scient... more Underdetermination of theories by empirical data is a central theme in debates surrounding scientific realism. Underdetermination undermines epistemological optimism: if empirical evidence cannot decide between theories, skepticism about the progress of science seems justified. Philosophical defenses have been developed against this skeptical threat. Typical themes in these defenses are that significant scientific examples of empirical equivalence (as opposed to imaginary armchair cases) are virtually non-existent, as it is already difficult enough in scientific practice to develop one single satisfactory theory; that in the rare instances where empirical equivalence can be maintained to occur it is defeasible and only temporary; and that there usually will be substantial differences in empirical support, even if theories are empirically equivalent. Examples are usually constructed cases within classical physics that have not played an important role in actual history. In this article we draw attention to the present-day situation in quantum mechanics, which we think is very relevant to the issue. There exist several realist interpretations of quantum mechanics, each of which depicts a quite distinctive physical world, and each of which has its own circle of devotees in the scientific community. Most of these interpretations are empirically equivalent in a quite strong sense: they predict the same results for all experiments that can be expected to be feasible. The usual arguments against the significance of theoretical underdetermination seem to lose a great deal of their effectiveness here. One may wonder whether non-uniqueness of theories is not part and parcel of the practice of modern science after all, and much less threatening than often thought.
Foundations of Physics, 2014
The suggestion that particles of the same kind may be indistinguishable in a fundamental sense, e... more The suggestion that particles of the same kind may be indistinguishable in a fundamental sense, even so that challenges to traditional notions of individuality and identity may arise, has first come up in the context of classical statistical mechanics. In particular, the Gibbs paradox has sometimes been interpreted as a sign of the untenability of the classical concept of a particle and as a premonition that quantum theory is needed. This idea of a 'quantum connection' stubbornly persists in the literature, even though it has also been criticized frequently. Here we shall argue that although this criticism is justified, the proposed alternative solutions have often been wrong and have not put the paradox in its right perspective. In fact, the Gibbs paradox is unrelated to fundamental issues of particle identity; only distinguishability in a pragmatic sense plays a role (in this we develop ideas of van Kampen 10), and in principle the paradox always is there as long as the concept of a particle applies at all. In line with this we show that the paradox survives even in quantum mechanics, in spite of the quantum mechanical (anti-)symmetrization postulates.
New Directions in the Philosophy of Science, 2014
The relation between physics and metaphysics is a traditional subject for debate in the philosoph... more The relation between physics and metaphysics is a traditional subject for debate in the philosophy of science. Since the days of Mach and other empiricists, who objected against any intrusion of metaphysics into physics, the philosophical climate has certainly become less anti-metaphysical. But it seems still uncontroversial that metaphysical doctrines that do not make fruitful contact with science and introduce concepts that are superfluous from a scientific point of view cannot be considered to be supported by what we know from science. Conversely, such doctrines lack the force to reform science.In his paper “Causal Probabilities in the GRW Quantum Mechanics” Tomasz Placek constructs a mathematical framework that permits a reading of the GRW theory (a variation on quantum mechanics) in terms of graded possibilities, “causal powers”. Here we shall comment on the wider philosophical research program that motivates this work. We shall argue – in line with the above general remarks – that it is dubious methodology to look to the GRW theory in order to find quantum mechanical support for the metaphysics of causal powers. Moreover, we shall argue that the technical strategy of Placek’s paper, namely the construction of a formal probabilistic framework, is metaphysically neutral and therefore unable to favor a powers ontology.
Synthese, 2005
Achieving understanding of nature is one of the aims of science. In this paper we offer an analys... more Achieving understanding of nature is one of the aims of science. In this paper we offer an analysis of the nature of scientific understanding that accords with actual scientific practice and accommodates the historical diversity of conceptions of understanding. Its core idea is a general criterion for the intelligibility of scientific theories that is essentially contextual: which theories conform to this criterion depends on contextual factors, and can change in the course of time. Our analysis provides a general account of how understanding is provided by scientific explanations of diverse types. In this way, it reconciles conflicting views of explanatory understanding, such as the causal-mechanical and the unificationist conceptions.
Physics Letters A, 2000
Modal interpretations of quantum mechanics assign definite properties to physical systems and spe... more Modal interpretations of quantum mechanics assign definite properties to physical systems and specify single-time joint probabilities of these properties. We show that a natural extension, applying to properties at several times, can be given if a decoherence condition is satisfied. This extension defines "histories" of modal properties. We suggest a modification of the modal interpretation, that offers prospects of a more general applicability of the histories concept. Finally, we sketch a proposal to apply the procedure for finding histories and a many-times probability distribution to the context of algebraic quantum field theory. We show that this leads to results that are relativistically invariant.
Physics Letters A, 1995
We show that the modal interpretation of quantum mechanics follows from essentially two demands: ... more We show that the modal interpretation of quantum mechanics follows from essentially two demands: (1) Definite properties are to be ascribed to physical systems in such a way that the magnitudes which are definite are definable solely from the quantum state and the structure of Hilbert space; (2) There is a one-to-one relation between properties possessed by a system and properties of its environment.
American Journal of Physics, 1990
It is argued that nonrelativistic quantum mechanics does not in all respects behave as a fully Ga... more It is argued that nonrelativistic quantum mechanics does not in all respects behave as a fully Galilean invariant theory. The difference is empirically significant, as is illustrated by the Sagnac effect. The conclusion of this article sheds some new light on a recent discussion concerning the status of de Broglie's theory of matter waves.
Niels Bohr and the Philosophy of Physics, 2017
It has often been remarked that Bohr's writings on the interpretation of quantum mechanics make s... more It has often been remarked that Bohr's writings on the interpretation of quantum mechanics make scant reference to the mathematical formalism of quantum theory; and it has not infrequently been suggested that this is another symptom of the general vagueness, obscurity and perhaps even incoherence of Bohr's ideas. Recent years have seen a reappreciation of Bohr, however. In this article we broadly follow this "rehabilitation program". We offer what we think is a simple and coherent reading of Bohr's statements about the interpretation of quantum mechanics, basing ourselves on primary sources and making use of-and filling lacunas in-recent secondary literature. We argue that Bohr's views on quantum mechanics are more firmly connected to the structure of the quantum formalism than usually acknowledged, even though Bohr's explicit use of this formalism remains on a rather global and qualitative level. In our reading, Bohr's pronouncements on the meaning of quantum mechanics should first of all be seen as responses to concrete physical problems, rather than as expressions of a preconceived philosophical doctrine. In our final section we attempt a more detailed comparison with the formalism and conclude that Bohr's interpretation is not far removed from present-day non-collapse interpretations of quantum mechanics.
Recherche, 2012
Livre: Probabilities, laws, and structures (series: the philosophy of science in a european persp... more Livre: Probabilities, laws, and structures (series: the philosophy of science in a european perspective) DIEKS Dennis, GONZALEZ Wenceslao J., HARTMANN Stephan, STöLTZNER Michael, WEBER Marc.
Cornell University - arXiv, Feb 4, 2021
According to the "Received View" identical quantum particles are a previously unknown kind of obj... more According to the "Received View" identical quantum particles are a previously unknown kind of objects that do not possess individuality. In this Chapter we discuss this view, criticize it, and propose an alternative. According to this alternative view so-called "identical quantum particles" should in many cases not be seen as objectsparticles-at all. However, there are situations in which a particle picture does become applicable. But the particles that emerge in these cases are distinguishable individuals, unlike the particles of the Received View.
Foundations of Physics
The theories of pre-quantum physics are standardly seen as representing physical systems and thei... more The theories of pre-quantum physics are standardly seen as representing physical systems and their properties. Quantum mechanics in its standard form is a more problematic case: here, interpretational problems have led to doubts about the tenability of realist views. Thus, QBists and Quantum Pragmatists maintain that quantum mechanics should not be thought of as representing physical systems, but rather as an agent-centered tool for updating beliefs about such systems. It is part and parcel of such views that different agents may have different beliefs and may assign different quantum states. What results is a collection of agent-centered perspectives rather than a unique representation of the physical world. In this paper we argue that the problems identified by QBism and Quantum Pragmatism do not necessitate abandoning the ideal of representing the physical world. We can avail ourselves of the same puzzle-solving strategies as employed by QBists and pragmatists by adopting a persp...
What is Quantum Information?
Fundamental Theories of Physics, 2020
Hermann Weyl connected his epoch-making work on general relativity and gauge theory to his Husser... more Hermann Weyl connected his epoch-making work on general relativity and gauge theory to his Husserlian views about the phenomenological essence of space and time. This philosophical stance of Weyl's has received considerable attention in recent years and has been favorably compared and contrasted with the "logicalempiricist" approach of Reichenbach, Weyl's contemporary who wrote extensively about relativity and the philosophy of space and time. We will argue, however, that Weyl's use of phenomenology should be seen as a case of personal heuristics rather than as a systematic and viable philosophy of physics. We will explain and defend Reichenbach's sophisticated empiricism, which in our opinion has often been misunderstood, and argue that it is better suited as a general philosophical framework for the natural sciences than Weyl's phenomenology. In the second half of the nineteenth and the beginning of the twentieth century Kant's original version of this "synthetic a priori" doctrine came under increasing
arXiv: History and Philosophy of Physics, 2018
In his Autobiographical Notes, Einstein mentioned that on his road to the final theory of general... more In his Autobiographical Notes, Einstein mentioned that on his road to the final theory of general relativity it was a major difficulty to accustom himself to the idea that coordinates need not possess an immediate physical meaning in terms of lengths and times. This appears strange: that coordinates are conventional markers of events seems an obvious fact, already familiar from pre-relativistic physics. In this paper we explore the background of Einsteins difficulties, going from his 1905 paper on special relativity, through his 1907 and 1911 papers on the consequences of the equivalence principle, to the 1916 review paper on the general theory. As we shall argue, Einstein's problems were intimately connected to his early methodology, in which clarity achieved by concrete physical pictures played an essential role; and to the related fact that on his route to the general theory he focused on special situations that were easily accessible to physical intuition. The details of thi...
European Studies in Philosophy of Science, 2019
The Scientific Revolution is often associated with a transition to a “mechanistic” world view. Ho... more The Scientific Revolution is often associated with a transition to a “mechanistic” world view. However, “mechanization” is not the term that best captures the distinctive nature of modern physics: “mathematization” would be a better characterization. Modern physics attempts to find mathematical relations between quantities, and does not require that these relations be interpreted in terms of mechanisms. Moreover, in modern physics there are cases in which it is unnatural to give the mathematical formalism a mechanistic interpretation, even if “mechanistic” is broadly construed. Both on the level of ontology and that of explanation physics turns out to be more general and liberal than what is suggested by the catchphrase that physics explains by identifying mechanisms. Although mechanistic explanation remains an important conceptual tool, in particular for achieving understanding, it is not the only one available and cannot lay claim to fundamentality.
The peculiarities of rotating frames of reference played an important role in the genesis of gene... more The peculiarities of rotating frames of reference played an important role in the genesis of general relativity. Considering them, Einstein became convinced that coordinates have a different status in the general theory of relativity than in the special theory. This line of thinking was confused, however. To clarify the situation we investigate the relation between coordinates and the results of space-time measurements in rotating reference frames. We argue that the difference between rotating systems (or accelerating systems in general) and inertial systems does not lie in a different status of the coordinates (which are conventional in all cases), but rather in different global chronogeometric properties of the various reference frames. In the course of our discussion we comment on a number of related issues, such as the question of whether a consideration of the behavior of rods and clocks is indispensable for the foundation of kinematics, the influence of acceleration on the beh...
Quantum Worlds, 2019
Experimental evidence of the last decades has made the status of "collapses of the wave function"... more Experimental evidence of the last decades has made the status of "collapses of the wave function" even more shaky than it already was on conceptual grounds: interference effects turn out to be detectable even when collapses are typically expected to occur. Non-collapse interpretations should consequently be taken seriously. In this paper we argue that such interpretations suggest a perspectivalism according to which quantum objects are not characterized by monadic properties, but by relations to other systems. Accordingly, physical systems may possess different properties with respect to different "reference systems". We discuss some of the relevant arguments, and argue that perspectivalism both evades recent arguments that single-world interpretations are inconsistent and eliminates the need for a privileged rest frame in the relativistic case.
European Studies in Philosophy of Science, 2019
Varieties of Scientific Realism, 2017
Underdetermination of theories by empirical data is a central theme in debates surrounding scient... more Underdetermination of theories by empirical data is a central theme in debates surrounding scientific realism. Underdetermination undermines epistemological optimism: if empirical evidence cannot decide between theories, skepticism about the progress of science seems justified. Philosophical defenses have been developed against this skeptical threat. Typical themes in these defenses are that significant scientific examples of empirical equivalence (as opposed to imaginary armchair cases) are virtually non-existent, as it is already difficult enough in scientific practice to develop one single satisfactory theory; that in the rare instances where empirical equivalence can be maintained to occur it is defeasible and only temporary; and that there usually will be substantial differences in empirical support, even if theories are empirically equivalent. Examples are usually constructed cases within classical physics that have not played an important role in actual history. In this article we draw attention to the present-day situation in quantum mechanics, which we think is very relevant to the issue. There exist several realist interpretations of quantum mechanics, each of which depicts a quite distinctive physical world, and each of which has its own circle of devotees in the scientific community. Most of these interpretations are empirically equivalent in a quite strong sense: they predict the same results for all experiments that can be expected to be feasible. The usual arguments against the significance of theoretical underdetermination seem to lose a great deal of their effectiveness here. One may wonder whether non-uniqueness of theories is not part and parcel of the practice of modern science after all, and much less threatening than often thought.
Foundations of Physics, 2014
The suggestion that particles of the same kind may be indistinguishable in a fundamental sense, e... more The suggestion that particles of the same kind may be indistinguishable in a fundamental sense, even so that challenges to traditional notions of individuality and identity may arise, has first come up in the context of classical statistical mechanics. In particular, the Gibbs paradox has sometimes been interpreted as a sign of the untenability of the classical concept of a particle and as a premonition that quantum theory is needed. This idea of a 'quantum connection' stubbornly persists in the literature, even though it has also been criticized frequently. Here we shall argue that although this criticism is justified, the proposed alternative solutions have often been wrong and have not put the paradox in its right perspective. In fact, the Gibbs paradox is unrelated to fundamental issues of particle identity; only distinguishability in a pragmatic sense plays a role (in this we develop ideas of van Kampen 10), and in principle the paradox always is there as long as the concept of a particle applies at all. In line with this we show that the paradox survives even in quantum mechanics, in spite of the quantum mechanical (anti-)symmetrization postulates.
New Directions in the Philosophy of Science, 2014
The relation between physics and metaphysics is a traditional subject for debate in the philosoph... more The relation between physics and metaphysics is a traditional subject for debate in the philosophy of science. Since the days of Mach and other empiricists, who objected against any intrusion of metaphysics into physics, the philosophical climate has certainly become less anti-metaphysical. But it seems still uncontroversial that metaphysical doctrines that do not make fruitful contact with science and introduce concepts that are superfluous from a scientific point of view cannot be considered to be supported by what we know from science. Conversely, such doctrines lack the force to reform science.In his paper “Causal Probabilities in the GRW Quantum Mechanics” Tomasz Placek constructs a mathematical framework that permits a reading of the GRW theory (a variation on quantum mechanics) in terms of graded possibilities, “causal powers”. Here we shall comment on the wider philosophical research program that motivates this work. We shall argue – in line with the above general remarks – that it is dubious methodology to look to the GRW theory in order to find quantum mechanical support for the metaphysics of causal powers. Moreover, we shall argue that the technical strategy of Placek’s paper, namely the construction of a formal probabilistic framework, is metaphysically neutral and therefore unable to favor a powers ontology.
Synthese, 2005
Achieving understanding of nature is one of the aims of science. In this paper we offer an analys... more Achieving understanding of nature is one of the aims of science. In this paper we offer an analysis of the nature of scientific understanding that accords with actual scientific practice and accommodates the historical diversity of conceptions of understanding. Its core idea is a general criterion for the intelligibility of scientific theories that is essentially contextual: which theories conform to this criterion depends on contextual factors, and can change in the course of time. Our analysis provides a general account of how understanding is provided by scientific explanations of diverse types. In this way, it reconciles conflicting views of explanatory understanding, such as the causal-mechanical and the unificationist conceptions.
Physics Letters A, 2000
Modal interpretations of quantum mechanics assign definite properties to physical systems and spe... more Modal interpretations of quantum mechanics assign definite properties to physical systems and specify single-time joint probabilities of these properties. We show that a natural extension, applying to properties at several times, can be given if a decoherence condition is satisfied. This extension defines "histories" of modal properties. We suggest a modification of the modal interpretation, that offers prospects of a more general applicability of the histories concept. Finally, we sketch a proposal to apply the procedure for finding histories and a many-times probability distribution to the context of algebraic quantum field theory. We show that this leads to results that are relativistically invariant.
Physics Letters A, 1995
We show that the modal interpretation of quantum mechanics follows from essentially two demands: ... more We show that the modal interpretation of quantum mechanics follows from essentially two demands: (1) Definite properties are to be ascribed to physical systems in such a way that the magnitudes which are definite are definable solely from the quantum state and the structure of Hilbert space; (2) There is a one-to-one relation between properties possessed by a system and properties of its environment.
American Journal of Physics, 1990
It is argued that nonrelativistic quantum mechanics does not in all respects behave as a fully Ga... more It is argued that nonrelativistic quantum mechanics does not in all respects behave as a fully Galilean invariant theory. The difference is empirically significant, as is illustrated by the Sagnac effect. The conclusion of this article sheds some new light on a recent discussion concerning the status of de Broglie's theory of matter waves.
Niels Bohr and the Philosophy of Physics, 2017
It has often been remarked that Bohr's writings on the interpretation of quantum mechanics make s... more It has often been remarked that Bohr's writings on the interpretation of quantum mechanics make scant reference to the mathematical formalism of quantum theory; and it has not infrequently been suggested that this is another symptom of the general vagueness, obscurity and perhaps even incoherence of Bohr's ideas. Recent years have seen a reappreciation of Bohr, however. In this article we broadly follow this "rehabilitation program". We offer what we think is a simple and coherent reading of Bohr's statements about the interpretation of quantum mechanics, basing ourselves on primary sources and making use of-and filling lacunas in-recent secondary literature. We argue that Bohr's views on quantum mechanics are more firmly connected to the structure of the quantum formalism than usually acknowledged, even though Bohr's explicit use of this formalism remains on a rather global and qualitative level. In our reading, Bohr's pronouncements on the meaning of quantum mechanics should first of all be seen as responses to concrete physical problems, rather than as expressions of a preconceived philosophical doctrine. In our final section we attempt a more detailed comparison with the formalism and conclude that Bohr's interpretation is not far removed from present-day non-collapse interpretations of quantum mechanics.
Recherche, 2012
Livre: Probabilities, laws, and structures (series: the philosophy of science in a european persp... more Livre: Probabilities, laws, and structures (series: the philosophy of science in a european perspective) DIEKS Dennis, GONZALEZ Wenceslao J., HARTMANN Stephan, STöLTZNER Michael, WEBER Marc.
Cornell University - arXiv, Feb 4, 2021
According to the "Received View" identical quantum particles are a previously unknown kind of obj... more According to the "Received View" identical quantum particles are a previously unknown kind of objects that do not possess individuality. In this Chapter we discuss this view, criticize it, and propose an alternative. According to this alternative view so-called "identical quantum particles" should in many cases not be seen as objectsparticles-at all. However, there are situations in which a particle picture does become applicable. But the particles that emerge in these cases are distinguishable individuals, unlike the particles of the Received View.
On 26 December 2008, Pekka Johannes Lahti celebrated his 60th birthday. To mark this occasion, tw... more On 26 December 2008, Pekka Johannes Lahti celebrated his 60th birthday. To mark this occasion, two special issues of this journal have been set aside to collect contributions from Pekka's students, friends and colleagues to pay tribute to his scientific achievements.