1,721,008 research outputs found
La disuguaglianza di Bell
Full text linkA partire dal famoso argomento di Einstein, Podolsky e Rosen del 1935, fi- no alla ormai conclamata violazione sperimentale della disuguaglianza di Bell (Aspect et al. 1982), il dibattito filosofico e scientifico su meccanica quantistica e località è divenuto sterminato. Non è certo possibile in queste poche pagine darne conto in modo anche lontanamente esaustivo. Per questa ragione, in occasione del centenario della relatività generale di Einstein (1915-2015), abbiamo scelto un modo peculiare di introdurre il tema della disuguaglianza di Bell. Come recentemente ha mostrato Don Howard (2015), Einstein avrebbe rinunciato più volentieri al determinismo che alla separabilità. Proviamo allora a vedere come si possa interpretare la violazione sperimentale della disuguaglianza di Bell alla luce di questa istanza ontologica
A physical interpretation of Lewis’ discrepancy between personal and external time in time travel
No full textAbstract This paper deals with those time travels mostly considered by physics,
namely those in the form of the so-called closed timelike curves. Some authoritative
scholars have raised doubts about the status of these journeys as proper time travels.
By using David Lewis’ famous definition of time travels proposed in 1976, we show
that this proper status may actually be recovered, at least in some cosmological contexts
containing spacetime regions, such as those concerning black holes described
by the Kerr–Newman metric, that allow the formation of local closed curves. But,
the mathematical incompatibility between ordinary black hole solutions to Einstein
field equations and the cosmological solutions induces us to take into consideration
the more general issue pertaining to the slippery interplay between models related to
local and global aspects of the world, highlighting, in particular, the different notions
of time that these domains inevitably imply. This leads us to think that time is not
a univocal entity of the world, but is a scale-related characteristic which claims the
adoption, when investigating its ontological status, of a sort of regional approach.We
also briefly dwell upon themost appropriate form of realism that such a kind of dispute
between local and global models may involve
No-Thing and Causality in Realistic Non-Standard Interpretations of the Quantum Mechanical Wave Function: Ex Nihilo Aliquid?
Full text linkIt has been shown that quantum mechanics in its orthodox interpretation violates four different formulations of causality principle endowed with empirical meaning. The present work aims to highlight how even a realistic non-standard interpretation of the theory conflicts with causality in its Cartesian formulation of the principle of the non-inferiority of causes over effects. Such an interpretation, which attributes some form of weak physical reality to the wave function (called empty wave, regarded as a zero-energy wave-like phenomenon), is a sort of precursor of the more recent so-called wavefunction realism. We also discuss a more radical realistic interpretation according to which physical properties can also be assigned to non-metaphysical relative nothing, seen as the simple absence of a particle such as a photon, but not of its corresponding state (no-photon), which is considered real. By interpreting the wave function collapse as a consequence of an interaction with empty waves or of a detection of the no-photon, we will highlight how more real physical effects can derive from lower causes, including relative nothing. Finally, we will show how these interpretations, while violating Cartesian causality in its two variants, do not seem to affect the validity of the principle of a rational explanation that nothing can derive from (absolute) nothing, which does not seem satisfied by the orthodox interpretation
Considerazioni storico-epistemologiche sul principio cosmologico
Full text linkQuello che oggi viene chiamato “principio cosmologico”, cioè l’ipotesi che l’universo sia omogeneo e isotropo, è stato introdotto implicitamente da Einstein nel 1917. Il termine “principio cosmologico” è però dovuto a Milne, che ne sviluppa i dettagli fisici e lo pone come una sorta di uniformità valida a priori, essenziale per fare cosmologia. McCrea per primo chiarirà che il principio cosmologico va ricondotto nell’alveo del metodo ipotetico-deduttivo delle scienze empiriche. Tale metodo formulato per la prima volta da Huygens nel ‘600, ribadito da Whewell nell’800 e da Campbell ed Einstein stesso nel ‘900, è spesso poco presente nella mentalità degli scienziati, che sono invece perlopiù legati agli slogan di Newton “non faccio ipotesi” e “dedurre dall’esperienza”. Purtroppo tale consapevolezza metodologica riguardo al principio cosmologico verrà di nuovo persa, tanto che oggi troviamo posizioni empiriste, come quella di Ellis, che basa il principio cosmologico sull’osservazione e su un presunto “principio copernicano”, che sembra invece una tipica fallacia probabilistica. La logica inferenziale che sovraintende alla cosmologia contemporanea è in realtà molto semplice, benché audace: dalla validità universale della relatività generale assieme al principio cosmologico si deduce il modello standard, che per ora, almeno in certi ambiti, è confermato. Ne segue che per ora non dobbiamo abbandonare nessuna di queste due assunzioni. È chiaro che ulteriori scoperte sperimentali e teoriche potranno convincerci a respingere questa deduzione, eliminando l’uno o l’altro dei due presupposti
Scientific progress
No full textAbstract We deal with the problem of verisimilitude, a notion which, roughly
speaking, tries to capture how close a scientific theory is to the truth. Our starting
philosophical basis is Evandro Agazzi’s approach and his view on scientific objectivity
which relies on his particular meaning of ‘partial truth’. By following an
epistemological approach to the verisimilitude problem and adopting the semantic
view of theories, we develop our epistemological proposal about the comparative
evaluation of scientific theories and cognitive situations. Our proposal allows to
establish, in a qualitative way, in which sense a theory, or a cognitive situation, is
better (more verisimilar) than another
Is Einstein’s Interpretation of Quantum Mechanics Ψ-Epistemic?
Full text linkAbstract Harrigan and Spekkens (Found Phys 40:125–157, 2010), introduced the
infuential notion of an ontological model of operational quantum theory. Ontological
models can be either “epistemic” or “ontic.” According to the two scholars, Einstein
would have been one of the frst to propose an epistemic interpretation of quantum
mechanics. Pusey et al. (Nat Phys 8:475–478, 2012) showed that an epistemic
interpretation of quantum theory is impossible, so implying that Einstein had been
refuted. We discuss in detail Einstein’s arguments against the standard interpretation
of QM, proving that there is a misunderstanding in Harrigan and Spekkens’ attribution
of an epistemic perspective to Einstein, whose point of view was actually statistical,
but in a quasi-classical sens
Non-standard realistic models of quantum phenomena and new forms of complementarity
No full textThis paper addresses the problem of different complementary
interpretations of atomic phenomena. We take complementarity seriously
as a meaningful philosophical principle, in the same way that the same
principles to which complementarity limits simultaneous recourse, such as
realism and causality, are endowed with meaning.
We will then discuss the attempts to overcome the complementary relation
between waves and particles in a realistic sense by attributing an independent
physical reality to both wave-like and particle-like entities, showing the
negative results of such attempts, which instead reveal the validity of another
formulation of the principle of complementarity: the so-called smooth
complementarity, according to which wave and corpuscular representations
can mix without a rigid distinction, although one continues to manifest itself
at the expense of the other.
We will emphasize how a particularly weak realist interpretation of the
quantum mechanical wave function conflicts with a (strong) formulation of
the causal principle, and show the emergence of another form of classical
complementarity between the realist and causal interpretations, which may
assume a new smooth form even in this case. Complementarity confirms,
in this way, its central role in the foundations of quantum mechanics and
indicates at the same time how the philosophical interpretation of this theory,
from the point of view of both realism and causality, remains a meaningful
open question
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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