The Galilei invariance of classical dynamics does not automatically imply the third Newtonian axiom and the center of mass theorem. For the deduction of these theorems from Galilei invariance we must have, generally, a “kinematical potential” (Helmholtz) and a “potential function” (Clausius), respectively. In celestial mechanics it is possible to have conservation of the motion of the center of gravity but not of the mass center. In this case, the active and the passive masses are different (...) quantities. (shrink)

Neither geometric phases nor differences in geometric phases are generally invariant under time-dependent unitary transformations (unlike differences in total phases), in particular under local gauge transformations and Galilei transformations. (This was pointed out originally by Aharonov and Anandan, and in the case of Galilei transformations has recently been shown explicitly by Sjoeqvist, Brown and Carlsen.) In this paper, I introduce a phase, related to the standard geometric phase, for which phase differences are both gauge- and Galilei-invariant, and, (...) indeed, invariant under transformations to linearly accelerated coordinate systems. I discuss in what sense this phase can also be viewed as geometric, what its relation is to earlier proposals for making geometric phases invariant under gauge or Galilei transformations, and what is its classical analogue. I finally apply this invariant phase to Berry's derivation of the Aharonov-Bohm effect. (shrink)

Many agree that the pilot-wave theory is to be understood as a first-order theory, in which the law constrains the velocity of the particles. However, while Dürr, Goldstein and Zanghì maintain that the pilot-wave theory is Galilei invariant, Valentini argues that such a symmetry is mathematical but it has no physical significance. Moreover, some wavefunction realists insist that the pilot-wave theory is not Galilei invariant in any sense. It has been maintained by some that this disagreement originates in (...) the disagreement about ontology, as Valentini, contrary to Dürr, Goldstein and Zanghì, has been taken to endorse wavefunction realism. In this paper I argue that Valentini’s argument is independent of the choice of the ontology of matter: it is based of the notion of natural kinematics for a theory, and the idea that the kinematics should match the dynamics. If so, I also argue that there are several reasons to dispute Valentini’s claim that the kinematical symmetries should constrain dynamical ones. (shrink)

This paper deals with the concept of simultaneity in classical and relativistic physics as construed in terms of group-invariant equivalence relations. A full examination of Newton, Galilei and Poincaré invariant equivalence relations in ℝ4 is presented, which provides alternative proofs, additions and occasionally corrections of results in the literature, including Malament’s theorem and some of its variants. It is argued that the interpretation of simultaneity as an invariant equivalence relation, although interesting for its own sake, does not cut in (...) the debate concerning the conventionality of simultaneity in special relativity. (shrink)

According to the conventionalist doctrine of space elaborated by the French philosopher-scientist Henri Poincaré in the 1890s, the geometry of physical space is a matter of definition, not of fact. Poincaré’s Hertz-inspired view of the role of hypothesis in science guided his interpretation of the theory of relativity (1905), which he found to be in violation of the axiom of free mobility of invariable solids. In a quixotic effort to save the Euclidean geometry that relied on this axiom, Poincaré extended (...) the purview of his doctrine of space to cover both space and time. The centerpiece of this new doctrine is what he called the ‘‘principle of physical relativity,’’ which holds the laws of mechanics to be covariant with respect to a certain group of transformations. For Poincaré, the invariance group of classical mechanics defined physical space and time (Galilei spacetime), but he admitted that one could also define physical space and time in virtue of the invariance group of relativistic mechanics (Minkowski spacetime). Either way, physical space and time are the result of a convention. (shrink)

FIRST DAY INTERLOCUTORS: SALVIATI, SA- GREDO AND SIMPLICIO ALV. The constant activity which you Venetians display in your famous arsenal suggests to the ...

V pričujočem sklopu so prevedena izbrana pisma Galilea Galileija ter njegovih korespondentov o problematiki razmerja med naravoslovnim oz. filozofskim raziskovanjem in Svetim pismom in s to problematiko povezani dokumenti iz Vatikanskega tajnega arhiva iz obdobja t. i. Galileijevega prvega procesa. Sklop zaključuje Galileijeva Razprava o morskem plimovanju, ki vsebinsko sicer ne zadeva omenjene problematike, je pa nastala kot posledica takratnega dogajanja. Vsa pisma so prevedena po kritični izdaji Galileijevih del, Le Opere di Galileo Galilei, ur. Antonio Favaro, Barbèra, Firence (...) 1890–1909. Dokumenti iz Vatikanskega tajnega arhiva so prevedeni po kritični izdaji I documenti vaticani del processo di Galileo Galilei. Nuova edizione accresciuta, rivista e annotata da Sergio Pagano, Archivio segreto vaticano, Mesto Vatikan 2009. Prevod Mojca Mihelič. Besedili Galileo Galilei poklican h kardinalu Bellarminu in Ukor kardinala Roberta Bellarmina Galileu Galileiju je prevedel Gašper Kvartič. Opombe in komentarji Matjaž Vesel in Mojca Mihelič. (shrink)

This classic work proves the truth of the Copernican system over the Ptolemaic one, that the Earth revolves around the Sun.

In this paper I investigate, within the framework of realistic interpretations of the wave function in nonrelativistic quantum mechanics, the mathematical and physical nature of the wave function. I argue against the view that mathematically the wave function is a two-component scalar field on configuration space. First, I review how this view makes quantum mechanics non- Galilei invariant and yields the wrong classical limit. Moreover, I argue that interpreting the wave function as a ray, in agreement many physicists, (...) class='Hi'>Galilei invariance is preserved. In addition, I discuss how the wave function behaves more similarly to a gauge potential than to a field. Finally I show how this favors a nomological rather than an ontological view of the wave function. (shrink)

Escrevia Maurice Blondel em 1906: “Há muito tempo Platão e Spinoza disseram: ‘a filosofia é a aprendizagem da morte’, ou seja, é a antecipação da vida, da vida que para nós é indivisivelmente conhecimento e ação”. Seguindo uma metodologia dialética e fenomenológica, este trabalho pretende uma aproximação ao significado da filosofia como “aprendizagem da morte” ou “antecipação da vida”, tendo como orientação prioritária o texto da Action e os dois artigos que compõem Le point de départ de la recherche philosophique. (...) Será explicitada uma caracterização da vida humana como ação e, consequentemente, realização de uma tarefa. Neste ínterim, será elucidada a fenomenologia da ação como a realização da dialética da vontade humana, que deve, ao cabo de um longo processo, colocar o problema “da morte ou vida da ação”, o que corresponderá à própria questão da “morte ou vida da inteligência”, ou melhor, “da vida que para nós é indivisivelmente conhecimento e ação”. (shrink)

This dissertation is about the sense in which the laws of quantum theory distinguish between the past and the future. I begin with an account of what it means for quantum theory to make such a distinction, by providing a novel derivation of the meaning of "time reversal." I then show that if Galilei invariant quantum theory does distinguish a preferred direction in time, then this has consequences for the ontology of the theory. In particular, it requires matter to (...) admit "internal" degrees of freedom, in that the position observable generates a maximal abelian algebra. I proceed to show that this is not a purely quantum phenomenon, but can be expressed in classical mechanics as well. I then illustrate three routes for generating quantum systems that distinguish a preferred temporal direction in this way. (shrink)

The use of the axial vector representing a three-dimensional rotation makes the rotation representation much more compact by extending the trigonometric functions to vectorial arguments. Similarly, the pure Lorentz transformations are compactly treated by generalizing a scalar rapidity to a vector quantity in spatial three-dimensional cases and extending hyperbolic functions to vectorial arguments. A calculation of the Wigner rotation simplified by using the extended functions illustrates the fact that the rapidity vector space obeys hyperbolic geometry. New representations bring a Lorentz-invariant (...) fundamental equation of motion corresponding to the Galilei-invariant equation of Newtonian mechanics. (shrink)

A deterministic equation of the Hamilton-Jacobi type is proposed for a single particle:S t+(1/2m)(∇S)2+U{S}=0, whereU{S} is a certain operator onS, which has the sense of the potential of the self-generated field of a free particle. Examples are given of potentials that imply instability of uniform rectilinear motion of a free particle and yieldrandom fluctuations of its trajectory. Galilei-invariant turbulence-producing potentials can be constructed using a single universal parameter—Planck's constant. Despite the fact that the classical trajectory concept is retained, the (...) mechanics of the particle then admits quantum-type effects: an uncertainty relation, de Broglie-type waves and their interference, discrete energy levels, and zero-point fluctuations. (shrink)

This paper states and proves a precise sense in which, if all the measurable properties of an ordinary quantum mechanical system are ultimately derivable from position, then time in quantum mechanics can have no preferred direction. In particular, I show that when the position observable forms a complete set of commuting observables, Galilei invariant quantum mechanics is guaranteed to be time reversal invariant.

Protophysics and Special Theory of Relativity. First, a proposal for a constructive foundation of the Special Theory of Relativity by M. Buth is criticized and confronted with an alternative proposal by the author. The main idea is to solve the problem of transforming coordinates between inertial systems in terms of the General Theory of Measurement. Regarding transformations of co-ordinates as transformations of thecorresponding “functions of measurement” these functions have to meet two demands. 1. To identify measured values which are related (...) to different inertial systems and measuring procedures as the same magnitude, the ratio scale of length and duration has to be defined with respect to the whole class of inertial systems. 2. Using the concept of a certain physical magnitude, propositions about measuring devices are made which are invariant with respect to measuring procedures. As aconsequence every transformation between functions of measurement has to be an equivalence relation. The first demand leads to linearity, the second one reduces the set of permissible transformations between inertial systems to the alternative of Galilei- and Lorentz-transformation. The (im)possibility of putting an absolute simultaneity into practice decides between these transformations. (shrink)

We consider the problem of whether there are deterministic theories describing the evolution of an individual physical system in terms of the definite trajectories of its constituent particles and which stay in the same relation to quantum mechanics as Bohmian mechanics but which differ from the latter for what concerns the trajectories followed by the particles. Obviously, one has to impose on the hypothetical alternative theory precise physical requirements. We analyze various such constraints and we show step by step how (...) to meet them. This way of attacking the problem turns out to be useful also from a pedagogical point of view since it allows one to recall and focus on some relevant features of Bohm's theory. One of the central requirements we impose on the models we are going to analyze has to do with their transformation properties under the transformation of the extended Galilei group. In a context like the one we are interested in, one can put forward various requests that we refer to as physical and genuine covariance and invariance. Other fundamental requests are that the theory allows the description of isolated physical systems as well as that it leads to a solution (in the same sense as Bohmian mechanics) of the measurement problem. We show that, even when all the above conditions are taken into account, there are infinitely many inequivalent (from the point of view of the trajectories) bohmian-like theories reproducing the predictions of quantum mechanics. This raises some interesting questions about the meaning of Bohmian mechanics. (shrink)

According to the conventionalist doctrine of space elaborated by the French philosopher-scientist Henri Poincaré in the 1890s, the geometry of physical space is a matter of definition, not of fact. Poincaré’s Hertz-inspired view of the role of hypothesis in science guided his interpretation of the theory of relativity (1905), which he found to be in violation of the axiom of free mobility of invariable solids. In a quixotic effort to save the Euclidean geometry that relied on this axiom, Poincaré extended (...) the purview of his doctrine of space to cover both space and time. The centerpiece of this new doctrine is what he called the ‘‘principle of physical relativity,’’ which holds the laws of mechanics to be covariant with respect to a certain group of transformations. For Poincaré, the invariance group of classical mechanics defined physical space and time (Galilei spacetime), but he admitted that one could also define physical space and time in virtue of the invariance group of relativistic mechanics (Minkowski spacetime). Either way, physical space and time are the result of a convention. (shrink)

We consider the problem of uniqueness of certain simultaneity structures in flat spacetime. Absolute simultaneity is specifiled to be a non-trivial equivalence relation which is invariant under the automorphism group Aut of spacetime. Aut is taken to be the identity-component of either the inhomogeneous Galilei group or the inhomogeneous Lorentz group. Uniqueness of standard simultaneity in the first, and absence of any absolute simultaneity in the second case are demonstrated and related to certain group theoretic properties. Relative simultaneity with (...) respect to an additional structure X on spacetime is specified to be a non-trivial equivalence relation which is invariant under the subgroup in Aut that stabilises X. Uniqueness of standard Einstein simultaneity is proven in the Lorentzian case when X is an inertial frame. We end by discussing the relation to previous work of others. (shrink)

The Lorentz transformation of space and time between two reference frames is one of the pillars of the special relativity theory. As a result of the Lorentz transformation, space and time are only relative and are entangled, while the Minkowski metric is Lorentz invariant. For this reason, the Lorentz transformation is one of the major obstructions in the development of physical theories with quantized space and time. Here is described the Lorentz transformation of a physical system with a discrete dynamical (...) time and a continuous space that fulfills Lorentz invariance while approximating the Lorentz transformation at the time continuous limit and the Galilei transformation at the classical limit. Furthermore, the discreteness of time is not mixed with the continuous nature of space, making time distinct from space. (shrink)

Bohmian mechanics is a quantum theory without observers. This means that neither the act of observation nor the notion of observer play any role in defining the theory, the theory is not about observers and observation, and it explains all non relativistic quantum phenomena. The theory is about something primitive', the basic ontology, and the laws for that are given. Bohmian mechanics is a deterministic theory of point particles. Like Newtonian mechanics it is invariant under Galilei transformations, but unlike (...) Newtonian mechanics it is a first-order theory, acceleration is not a concept entering the law of motion. Rather this law directly determines the velocities of the particles as follows. (shrink)